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Microbiology Topics & Concepts Covered

Topics	Concepts
Microorganisms	Bacteria, viruses, fungi, archaea, protozoa
Cell Structure	Cell wall, cell membrane, cytoplasm, ribosomes
Virology	Virus structure, replication, viral diseases
Parasitology	Parasite life cycles, host-parasite interactions
Microbial Ecology	Ecosystems, biogeochemical cycles, symbiosis
Mycology	Fungal morphology, reproduction, fungal diseases
Bioremediation	Microbial cleanup of pollutants in the environment
Medical Microbiology	Infectious diseases, clinical microbiology

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Recently Asked Microbiology Questions

Expert help when you need it

Q1: In Lab 13: Food Preservation, which two foods do we make? See Answer
Q2:Write a reflective journal on the interaction of Microbes with humans and the environment. You can use the following link to acquaint yourself with the microbiome: http://learn.genetics.utah.edu/content/microbiome/ (Links to an external site.) Reflect on how the microbes are relevant in your life. How do microbes work with your body? How do your daily activities affect the microbes that shape your immune response during health and disease? In addition to your body, reflect on the role microbes play in the health of the environment and how our actions influence that equilibrium. See Answer
Q3:Write a reflective journal on the interaction of Microbes with humans and the environment. You can use the following link to acquaint yourself with the microbiome: http://learn.genetics.utah.edu/content/microbiome/ (Links to an external site.) Reflect on how the microbes are relevant in your life. How do microbes work with your body? How do your daily activities affect the microbes that shape your immune response during health and disease? In addition to your body, reflect on the role microbes play in the health of the environment and how our actions influence that equilibrium. See Answer
Q4:Understanding the epidemiology of infectious disease requires a significant commitment to data collection and dissemination. A. Describe in detail the diverse types of data required to diagnose disease at a population level B. Discuss how this data can be collated and disseminated C. Comment upon the changing nature of infections and consider the reasons for the appearance of some specific novel pathogens within the last 25 years See Answer
Q5:submit a photo of anything (natural, engineered, crafted, designed) that resembles an Microbiology structure (this includes histology, tissue organization, and micro-structures such as protein fibers/arrangements). Therefore, images may be of flowers, trees, the night sky, clouds, bridges, buildings, abstract art (2D/3D), rivers, oceans, ponds, pools, fruits, vegetables, etc... You will arrange the three images into a word document you create; one image is a photo of the Microbiology structure, the second photo is an annotated version of the photo outlining the Microbiology structure you identified, the third picture is a reference image (of actual Microbiology structures) to support submission.See Answer
Q6:Buffers should have which of the following characteristics? Select all that apply. They should be able to accept excess hydrogen ions They should be able to release excess hydrogen ions They should be able to accept hydroxide ions They should be able to release hydroxide ionsSee Answer
Q7:Question 3. Which of the following chemicals would be suitable buffers? Select all that apply. D HCI NaCl □ H₂O ⒸHCO3See Answer
Q8:Question 4. How do organic compounds differ? Select all that apply. O length branching O multiple bond variation O ring structure O presence of functional groupsSee Answer
Q9:Each student must post one (1) substantial initial post as a response to the discussion question with a minimum of 150 words by Wednesday at 11:59 PM. Review the module resources and read the scenario to answer the discussion questions. It is the Year 2056 and the first manned crew to land on Mars returned home after a 15-month round trip including 4 weeks living on Mars. Among their discoveries was a novel bacterium that showed potential in consuming all kinds of plastic which could help eliminate the harmful impact plastic disposal has on Earth's ecosystem. After careful testing and engineering, the bacterium was viewed as a viable and cost-efficient means of plastic pollution control and fully utilized by the waste disposal industry. Fifty years later, an epidemic ravaged the world in which a variant of this bacterium was discovered to be the cause. Most common symptoms included dysentery, fever, and general malaise; however, twenty percent of the general population developed severe rhabdomyolysis, a life-threatening condition that breaks down muscle. You are part of a group of representatives from the CDC fielding questions in a special Congressional hearing. One Senator looks at you and asks, "How can a plastic-eating bacteria turn into a muscle-eating bacteria? Why are only humans being affected?" Answer the Senator's questions. How can a plastic-eating bacteria turn into a muscle-eating bacteria? Why are only humans being affected? Use your imagination to develop a plausible scenario using the microbial genetics you have learned this week. Make sure you can explain and justify your reasoning.See Answer
Q10:1. Define the term ubiquitous and explain whether this term can be used appropriately to describe bacteria and archaea. 2. Based upon your knowledge of cell wall structure, explain how the microbes causing meningitis and typhoid fever can induce fever and systemic shock in an infected patient.See Answer
Q11:Q4. Compare what occurs during these two steps of lytic cycle of bacteriophage: ** *Entry: ***Replication:See Answer
Q12:1. After reading exercise 25, what would you consider an "extreme environment" for humans?See Answer
Q13: Topic: What are the benefits of cinnamon oil as an antibacterial agent against e coli for preventing food poisoning caused by? The report should include writing about cinnamon, E coli, why we use cinnamon instead of antibiotics, methods, results, discussion and reference Notes* write 4 methods from different articles and discuss them, which one is more effective and why?/n SEEK WISDOM THE UNIVERSITY OF WESTERN AUSTRALIA UWA School of Agriculture and Environment Semester 1, 2024 The Conduct, Ethics and Communication of Science (SCIE4403) Assessment 3b: Written Report Due date: Friday 24 May, 11:59am (midday) Mark allocation: 35% of unit total 1,500 words Word limit: Digital submission via LMS - assessments will be checked for plagiarism using Turnitin Overview Students will work on a literature review research project throughout semester with one other student. Assessment of your research project will consist of: 1) A 10-minute presentation with your research partner (Assessment 2) 2) A written report, prepared individually (Assessment 3b) Assessment 3b brief Assessment 3b tests your ability to synthesise and critically assess the literature, and your ability to communicate your findings clearly and concisely. Even though you will work together in conducting the research, you need to write up the report separately from your teammate. The report should follows a basic IMRAD¹ article structure, be well formatted, and follow APA 7th referencing style. Your submission will be assessed on content, format, and presentation. Your written report needs to include at least the following elements: 1. Title 2. Author(s) + affiliation(s) 3. Abstract that summarises the topic, results, and main conclusions in no more than 150 words² 4. Keywords that captured the topic, methods, and provide other additional useful information - not copying the title words. 5. Introduction and background to the issue(s) at hand. This section presents your topic, explains why the topic is important (why the readers should care), what is known about the topic (to identify knowledge gaps), and what you will do in this paper (through a research question or a hypothesis). 6. Description of the methods used and process followed to conduct the review. In this section, you describe the methods that YOU used and process followed. In the case of a 1 Introduction, Materials and Methods, Results, And Discussion. Most scientific articles follow this structure. ² Hint: look at the way in which scientific abstracts are written in David Lindsay's book on scientific writing. 1 蛋蛋 SEEK WISDOM THE UNIVERSITY OF WESTERN AUSTRALIA literature review, you describe what you did to find the papers you reviewed. What keywords you used, what databases were searched, how many relevant papers you found, and the criteria that you used to select the final papers to include in the review. 7. Results that synthesise your findings in text, tables, and figures where appropriate. Again, I emphasise that a synthesis is more than a simple regurgitation of previous papers, but should organise and summarise existing knowledge in a logical fashion that supports or disproves your research question or hypothesis. A good way to do this is to distil common findings or themes from the literature, and use those to structure your results. Marks will be deducted for results that simply rehash existing papers (e.g. "A (2004) said this... and B (2013) found this...."). 8. You can use tables, and figures to summarise your methodology or results where appropriate. You should always refer to tables and figures in the text, and interpret the main points of the figure/table in the body text. 9. The final sections are the Discussion and Conclusion. It is easiest if you present these as two separate sections. In the Discussion, you critically assess the results, point out flaws, and recommend what policy makers / researchers / relevant stakeholders should take away from your report. The Conclusion typically includes a one or two sentence summary of your work and an overall take-home message. 10. References should be in APA 7th style. Word limit The word limit for this assessment is 1,500 words. This includes ALL text including headers, in-text citations, footnotes, text in figures and tables, and figures and table captions. The word limit does NOT include your report title, abstract, keywords, and bibliography. Referencing You must use the APA citation-style in your submission, including for all figures and tables incorporated in the report from external sources. This unit includes lectures and workshops dedicated to scientific referencing and the APA-referencing style. If you are still uncertain about APA-style referencing, see: https://guides.library.uwa.edu.au/apa. Formatting Advice on formatting is provided in a unit style guide, which is available in the Assessment 3 folder on the LMS. Use consistent formatting of title, section headers, tables and figures, page numbers etc. Your paper should be written on A4 sized paper in portrait format. Limit fonts to Arial, Times New Roman, Calibri or Cambria in 11 or 12 point font size. Use page margins of at least 2 cm. 2 SEEK WISDOM THE UNIVERSITY OF WESTERN AUSTRALIA Marking criteria Component Weight Title, Abstract and 5% Keywords Introduction and 25% background to the issue Methods and 25% Results Tables and figures 7.5% Recommendations, 12.5% discussion, and conclusions Guide for marking criteria • Concise title and abstract that cover the content of the research • Keywords are appropriate and supplement title and abstract information • Clear, concise, and accurate description of the topic • Introduction frames the issue in a wider context • Objective of research is well articulated • Thorough and complete presentation of research methods, including appropriate graphics • Summary and insightfully synthesis of results • Balanced: objective, balanced presentation of results • Coherent: each result relates to the research question addressed • Analysis: a collection of studies is analysed for differences and commonalities about the topic • Tables and figures are relevant to the message that they aim to convey • Tables and figures have a concise and complete caption • Tables and figures are correctly formatted • No redundant tables or figures • All tables and figures are correctly referenced in the text • Information synthesises and brought to a logical conclusion • Discussion and conclusion reflect findings presented in Results section • Recommendations are evidence-based with well-develop reasoning • No new information in the concluding paragraph • Clear and concise conclusion • Logical structure that presents all major IMRDC elements • Uses text font types and sizes that facilitate the organisation, presentation, and enhance readability • No spelling, punctuation, or grammatical errors Appropriate language used Structure and format 7.5% Spelling, language, 7.5% grammar, and • style • English expression is concise and messages are clear Documentation 10% and quality of sources • Correct sentence structures • All data obtained from other sources is correctly referenced and consistent with APA-style • Reliance on scholarly literature • At least 6 appropriate academic papers are reviewed and cited correctly Questions It is normal to feel uncertain about how to go about completing an assessment, as you are learning new skills and knowledge. If you have any questions about this assessment, or the standards expected, please consult your tutor or ask a question on the Discussion Board. You will receive feedback on your progress if you complete the workshop activities in class. Here are some of the things the lecturer and unit co-ordinator will not do: • Read a draft of your assessment; • Correct the grammar or spelling in a draft of your assessment; • Comment on the quality of your references; Instruct you on how to reference something correctly in APA-style; Direct you individually towards specific references that would be helpful for your paper. 3 SEEK WISDOM THE UNIVERSITY OF WESTERN AUSTRALIA If you need assistance with English writing, researching, using the library, or other study skills, please seek help at StudySmarter (website: http://www.student.uwa.edu.au/learning/studysmarter). Submission process All written work has to be submitted via the LMS using the Turnitin submission link. Only written reports submitted via Turnitin can be marked. Turnitin is set to give you feedback on draft submissions, so please use this feature if you want to check your work prior to submitting your final draft. • • You may submit a Word-document or PDF-file. You need to give your file the following title, where you replace the relevant details that apply to you: < insert name_insert student number_SCIE4403 Assessment 3b>. • The first page of your assessment should be the cover sheet that is provided in the LMS. Late submission A penalty of 5 per cent of the total mark allocated for the assessment item is deducted per day for the first 7 days (including weekends and public holidays) after which the assessment is not accepted. Each 24-hour block is recorded from the time the assessment is due. For example, if an assessment is late by three days and was given 45 out of a possible mark of 50, you would receive a mark of 37.5 out of 50 after the late penalty (2.5 is deducted per day). Penalty for exceeding word limit This assessment has a maximum word limit of 1,500 words. Where a submitted assessment exceeds the word limit, a penalty of 1 per cent of the total mark allocated for the assessment task applies for each 1 per cent in excess of the word limit (i.e. for every 15 words over 1,500 words). Resources The research techniques required for this assessment will be practiced throughout the unit. Students are recommended to refer to the unit textbook by David Lindsay (2020) "Scientific Writing = Thinking in Words". In particular: • Chapter 2: Article structure • Chapters 3-9: Writing • Chapters 10-11: Editing for readability • Chapter 15: Literature reviews You are also encouraged to consult the Writing and Editing module in the UWA Study Success unit, which provides a lot of useful guidance on preparing academic writing tasks. SEEK WISDOM THE UNIVERSITY OF WESTERN AUSTRALIA Link to unit outcomes Completing this assessment will contribute to three of the unit outcomes for this course. See below for an explanation. (1) Demonstrate an understanding of the theory and technical skills that are needed to communicate science effectively to various audiences; Writing scientific papers or technical reports are core technical skills that you will need in nearly every job. This assessment will develop your technical skills to write clearly and effectively. (2) Conduct ethical research, which includes acquiring, managing, and sharing of data in a way that respects the personal and intellectual property of the owner, avoiding plagiarism, and fostering inclusive authorship; This assessment will require you to conduct a literature review in a way that follows core scientific values and properly reference your sources in your written report. (3) Demonstrate scientific literacy skills, and using this to write an appropriately structured scientific article to a high professional standard; Assessment 3 is the core assessment addressing this learning outcome. 5See Answer
Q14:Project 1: Non-Equilibrium Separations in The Real World Non-equilibrium separation processes are constantly being developed and optimized for use in a range of industries including (but not limited to): petroleum, food production, pharmaceuticals, defense, green energy, and consumer products. This research is conducted both in industrial R&D departments and in academic research laboratories. For this project, you need to select an article from the literature that presents on a topic we have covered in the "non-equilibrium separations" portion of the class (batch distillation, drying, crystallization, membrane separations, adsorption, ion exchange, chromatography). You will then use this article to develop a homework-style problem with significant background and detailed solutions. Tasks: 1. Select an article 2. Background/Introduction: Please summarize the process described in the paper, both the details of the paper and the theory that underlies the separation process. This will likely require research beyond your chosen article. Remember to cite all sources and include a bibliography of the literature you reference. In particular, please discuss: a. The relevant background information for understanding the paper and problem statement including the theory discussed in class b. Why this separation process is being studied. What are its advantages and disadvantages and how can it be/was it improved? c. The driving force at play during this separation d. The factors that were or could be optimized and how they would affect the separation (purity, rate, time required)/n APPLIED AND ENVIRONMENTAL MICROBIOLOGY, July 2000, p. 2914-2920 0099-2240/00/$04.00+0 Copyright © 2000, American Society for Microbiology. All Rights Reserved. Vol. 66, No. 7 Influence of Salts on Virus Adsorption to Microporous Filters+ JERZY LUKASIK,* TROY M. SCOTT, DIANE ANDRYSHAK, AND SAMUEL R. FARRAH Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611-0700 Received 15 March 1999/Accepted 11 April 2000 We investigated the direct and indirect effects of mono-, di-, and trivalent salts (NaCl, MgCl2, and AICI) on the adsorption of several viruses (MS2, PRD-1, X174, and poliovirus 1) to microporous filters at different pH values. The filters studied included Millipore HA (nitrocellulose), Filterite (fiberglass), Whatman (cellulose), and 1MDS (charged-modified fiber) filters. Each of these filters except the Whatman cellulose filters has been used in virus removal and recovery procedures. The direct effects of added salts were considered to be the ef- fects associated with the presence of the soluble salts. The indirect effects of the added salts were considered to be (i) changes in the pH values of solutions and (ii) the formation of insoluble precipitates that could adsorb viruses and be removed by filtration. When direct effects alone were considered, the salts used in this study promoted virus adsorption, interfered with virus adsorption, or had little or no effect on virus adsorption, depending on the filter, the virus, and the salt. Although we were able to confirm previous reports that the addition of aluminum chloride to water enhances virus adsorption to microporous filters, we found that the enhanced adsorption was associated with indirect effects rather than direct effects. The increase in viral ad- sorption observed when aluminum chloride was added to water was related to the decrease in the pH of the water. Similar results could be obtained by adding HCl. The increased adsorption of viruses in water at pH 7 following addition of aluminum chloride was probably due to flocculation of aluminum, since removal of flocs by filtration greatly reduced the enhancement observed. The only direct effect of aluminum chloride on virus adsorption that we observed was interference with adsorption to microporous filters. Under conditions under which hydrophobic interactions were minimal, aluminum chloride interfered with virus adsorption to Milli- pore, Filterite, and 1MDS filters. In most cases, less than 10% of the viruses adsorbed to filters in the presence of a multivalent salt and a compound that interfered with hydrophobic interactions (0.1% Tween 80 or 4 M urea). The effects of salts on virus adsorption to microporous filters have been studied for many years and have been discussed in several reviews (4, 13, 16, 17, 28). In previous studies, the researchers concluded that addition of aluminum ions (or mag- nesium ions) enhanced viral adsorption to microporous filters, and from these results it was concluded that the presence of salts is necessary for optimum viral adsorption to the filters (4, 13, 16, 17, 27, 28). However, we found two problems with the earlier studies. First, relatively few viruses and few micro- porous filters were studied. Much of the information was in- formation concerning the adsorption of poliovirus to nitro- cellulose filters (Millipore filters). However, due to recent developments in filter technology, new filters that have sub- stantially different properties than the filters previously studied are currently being used. Therefore, it is necessary to evaluate the effects of salts on these filters. Second, previous studies on the effects of salts on virus adsorption did not distinguish between direct and indirect ef- fects of the salts that influenced viral adsorption. The direct effects that have been proposed include formation of salt bridges between the viruses and the filters (16) and alteration of the charge of a filter (14). The indirect effects include (i) a decrease in the pH due to addition of aluminum salts to puri- fied water (28); (ii) the formation of flocs that adsorb viruses and are then physically trapped by the filters (9, 28); and (iii) * Corresponding author. Mailing address: Department of Microbi- ology and Cell Science, University of Florida, Gainesville, FL 32611- 0700. Phone: (352) 392-1885. Fax: (352) 392-5922. E-mail: george @micro.ifas.ufl.edu. + Paper number R-07534 from the Florida Agricultural Experiment Station, Gainesville. 2914 the reaction between aluminum ions and humic materials that interfere with virus adsorption (10, 25). In order to better understand the forces involved in viral adsorption to solids, we investigated the adsorption of four viruses to four commercially available filters having different compositions and different physical characteristics. Two of the filters used in this study (Filterite and 1MDS filters) are cur- rently used for recovering viruses from water (1, 2). The Fil- terite filters have a net negative charge at pH values near neutrality, in contrast to the 1MDS filters, which are positively charged or have a slight negative charge at similar pH values (14, 24). Nitrocellulose filters (Millipore HA filters) also have a net negative charge at pH 7 (14) and have been used in studies on virus adsorption and to recover viruses from water (6, 7, 12, 28). Cellulose filters (Whatman filters) were included as an example of filters that poorly adsorb viruses. These filters are made from material that is electronegative at pH 7 (26) and have little ability to adsorb viruses unless they are modified (11). Mono- and multivalent salts were used at different pH val- ues, and compounds that have been shown to disrupt hydro- phobic interactions were also used. In addition, the effects of different concentrations of aluminum and the effects of differ- ent concentrations of magnesium on pH and viral adsorption, respectively, were studied. The previously described direct and indirect effects were minimized by controlling flocculation and pH by filtering and buffering. All virus stocks and salt solutions were prefiltered through 0.2-μm-pore-size filters prior to each experiment to reduce the effects of aggregation and floccula- tion. The pH was monitored and controlled, and only purified water was used. Under these conditions, magnesium chloride was found to promote virus adsorption, to interfere with virus adsorption, and to have little or no effect on virus adsorption, Downloaded from https://journals.asm.org/journal/aem on 12 February 2024 by 128.138.65.188. VOL. 66, 2000 Percent Adsorption 120 100 80 60 40 20 0 0 -20 0.001 -1 MDS -HA 0.01 0.1 VIRUS ADSORPTION TO MICROPOROUS FILTERS PercentAdsorption 100 80 60 60 HA 40 +1MDS 20 2915 Magnesium Chloride Concentration (M) FIG. 1. Influence of magnesium chloride concentration on adsorption of poliovirus 1 to 1MDS and Millipore HA filters at pH 7. depending on the virus and the microporous filter tested. The most consistent effect of sodium chloride and aluminum chlo- ride on virus adsorption was to interfere with virus adsorption to 1MDS filters. MATERIALS AND METHODS Filtration of samples. All viral stocks and solutions were prefiltered through a 0.2-μm-pore-size filter (Millipore GS; Millipore Corp., Bedford, Mass.) that had been prewashed with 20 ml of deionized water before use. Viruses. The phages used in this study, their isoelectric points (1), and their hosts are as follows: MS2 (= ATCC 15597-B1), pl 3.9, Escherichia coli C-3000 (= ATCC 15597); X174 (= ATCC 13706-B1), pl 6.6, E. coli ATCC 13607; and PRD-1, pl 4.2, Salmonella typhimurium ATCC 19585. Numbers of phage PFU were determined by using the appropriate hosts and a soft-agar overlay (23). Poliovirus 1 (pl, approximately 4 and 7 [13]) was grown on BGM cells, and the number of poliovirus PFU was determined by an agar overlay method (22). Microporous filters. The flowing microporous filters were used: Millipore HA filters (nitrocellulose; Millipore Corp.); Filterite 0.20-μm-pore-size filters (bound fiberglass; Filterite Corp., Timonium, Md.); Whatman no. 5 filters (cellulose; Fischer Scientific, Pittsburgh, Pa.); and 1MDS filters (charge-modified fibers; AMF Cuno, Meridan, Conn.). The Filterite and 1MDS filters were purchased as cartridge filters. These filters were broken down, and smaller filters were cut from the filter material. The Millipore, Filterite, and Whatman filters are neg- atively charged at pH values near neutrality; the 1MDS filters are positively or slightly negatively charged at the same pH values (14, 19, 24, 26). Solutions. Solutions of sodium chloride, magnesium chloride, aluminum chlo- ride, urea, and Tween 80 were prepared with a buffer solution (0.02 M imid- azole-0.02 M glycine, unless otherwise indicated). The solutions were adjusted to the required pH by adding 1 M NaOH or 1 M HCl. Tap water was dechlorinated by adding 10 mg of sodium thiosulfate per liter. Deionized water (>15 MQ-cm) was obtained from a Barnstead NANOpure II unit. Aluminum chloride and magnesium chloride titration experiments. For alu- minum chloride and magnesium chloride titration experiments (Fig. 1 through 3), aliquots of a 1.00 M aluminum chloride or 1.00 M magnesium chloride solution were added to a 0.002 M glycine-0.002 M imidazole solution or to purified water to obtain the desired concentrations. Since the concentrations of salts used in these experiments were lower than the concentrations used in other experiments, a lower concentration of buffer was used to reduce interference with the metallic ions by buffer ions. In addition, aluminum chloride was added to deionized water, and the pH was recorded. The pH values of samples of deionized water were then adjusted with HCl to values that matched the pH values of the solutions described above that 0 0.0001 0.001 0.01 Aluminum Chloride Concentration (M) 0.1 FIG. 3. Influence of aluminum chloride concentration on adsorption of po- liovirus 1 to 1MDS and Millipore HA filters at pH 3.5. contained aluminum chloride. Virus adsorption experiments were then con- ducted by using samples containing aluminum chloride and samples containing HCl at the same pH value (Fig. 4). The pH values of all solutions were measured at the beginning and at the end of each experiment. Experimental procedure. Most experiments were conducted at pH 7.0 or 3.5. The lower pH (pH 3.5) was selected since it has been used in several other studies and is the recommended pH for recovering viruses in water when Filterite filters are used (2, 3, 18, 27). Also, the aluminum salts used (at the concentrations used) are soluble at pH 3.5. Aluminum salts were not used at pH 7 (Table 1 and 2) since they are relatively insoluble and form flocs that can adsorb viruses (8, 9). Viruses were added to solutions to obtain an initial titer of approximately 105 PFU/ml. The viruses in the solutions were assayed following dilution in 1% tryptic soy broth (Difco) for phages or in minimal essential medium supple- mented with 2% fetal calf serum for poliovirus. In each case the dilution was sufficient to raise the pH of the sample to approximately 7. To prevent floccu- lation when experiments were performed with aluminum chloride, an initial 1/10 dilution with deionized water was prepared, and then a second dilution with the dilution media described above was prepared. The filters used were 25-mm circles or filters cut into 25-mm circles and placed into stainless steel filter holders. One layer of Millipore HA filter material, two layers of Filterite filter material, two layers of Whatman no. 5 filter material, or three layers of 1MDS filter material were placed in each holder for the experiment. Each filter prep- aration was first rinsed with 60 ml of deionized water. Then 25 ml of the salt solution containing viruses was passed through each filter by using a mechanical syringe infusion pump (Harvard Apparatus Co., Millis, Mass.) at a flow rate 1.5 ml/s. The filter effluents were assayed for viruses, and the percentage removed was determined. A portion of each sample that had not been passed through any filter was assayed at the beginning and at the end of each experiment to deter- mine if the solutions inactivated the viruses. The numbers of viruses in the unfiltered and filtered samples were used to determine the percentages removed by the filters. Each experiment was performed in triplicate. In addition, each experiment was performed at least twice. Therefore, each value reported below represents a mean based on at least six determinations. The error associated with the values reported was less than √n, where n is the number of the PFU counted. A statistical analysis of the data obtained (standard deviations, slopes, correla- tion, and general t test probabilities) was performed by using PSI-Plot software (Poly Software International, Salt Lake City, Utah). Aluminum Chloride (M) 1.1E-7 6.3E-7 3.14E-6 4.9E-5 1.2E-5 1.9E-4 7.8E-4 3.1E-3 1.3E-2 0.05 Percent Adsorption 60 282222° 120 100 80 40 20 0 0 1 MDS --HA Percent Adsorption 120 100 60 80 60 40 40 20 0 Buffer Aluminum chloride. 0.001 0.01 Magnesium Chloride Concentration (M) 0.1 FIG. 2. Influence of magnesium chloride concentration on adsorption of poliovirus 1 to 1MDS and Millipore HA filters at pH 3.5. 7 6 5.2 4.9 4.65 4.42 4.18 3.96 3.72 3.43 pH FIG. 4. Influence of aluminum chloride concentration and the corresponding pH of a buffer solution on adsorption of poliovirus 1 to Millipore HA filters. The pH values used corresponded to the pH values resulting from dissolution of aluminum chloride at the concentrations used. Downloaded from https://journals.asm.org/journal/aem on 12 February 2024 by 128.138.65.188. 2916 LUKASIK ET AL. TABLE 1. Effects of salts on virus adsorption to microporous filters at pH 7ª % Virus adsorption Buffer containing 0.1 M MgCl2 Filter Virus Buffer containing Buffer 0.1 M NaCl Millipore HA MS2 8 Ab 18 B 99 C PRD-1 6 A 8 A 59 B OX174 4 A 40 B 57 C Poliovirus 1 3 A 98 B Mean 5 41 99 B 79 Filterite MS2 6 A 21 B PRD-1 11 A 9 A OX174 3 A 3 A 23 B 10 A 5 A Poliovirus 1 10 A 9 A 99 B Mean 7 11 34 Whatman MS2 18 A 12 A 19 A PRD-1 7 A 3 A 6 A OX174 5 A 9 A 38 B Poliovirus 1 8 A 6 A Mean 10 8 17 1MDS MS2 96 A 10 B PRD-1 97 A 13 B 13 B OX174 29 A 12 B Poliovirus 1 Mean 79 A 7 B 75 11 18 C 9 B 12 5 A 7 B a We added approximately 105 PFU of virus to 25-ml portions of buffer, buffer containing 0.1 M NaCl, and buffer containing 0.1 M MgCl2, and each type of solution was passed through the different types of filters at a rate of 1.5 ml/s. The numbers of viruses in the influent and effluent were measured in order to determine the percentage of adsorption in each case. b Values on the same line followed by the same letter are not significantly different at P = 0.05. APPL. ENVIRON. MICROBIOL. the adsorption of poliovirus to filters is shown in Fig. 1 and 2. At pH 7, increasing the concentration of magnesium chloride increased poliovirus 1 adsorption to Millipore HA filters but decreased poliovirus 1 adsorption to 1MDS filters (Fig. 1). At pH 3.5, increasing the concentration of magnesium chloride (Fig. 2) did not affect adsorption of poliovirus 1 to Millipore HA filters but decreased poliovirus 1 adsorption to 1MDS filters. The effects of different concentrations of aluminum chloride on the adsorption of poliovirus to Millipore and 1MDS filters are shown in Fig. 3. Increasing the concentration of aluminum chloride had little effect on poliovirus adsorption to Millipore filters but interfered with adsorption of this virus to 1MDS filters. The Millipore and 1MDS filters differed in hydrophobic- ity. The contact angle for chloroform on Millipore filters was 144.2 ± 3.2°, and the contact angle for chloroform on 1MDS filters was 151.8 ± 1.6°, which showed that the Millipore filters were more hydrophobic. At pH 7 and in absence of salt ions, we observed little adsorption of poliovirus 1 in deionized water to Millipore HA filters (Fig. 4). As the concentration of aluminum chloride was increased, the adsorption of poliovirus increased. The pH val- ues of the solutions also decreased as aluminum chloride was added. When the pH values of samples of deionized water were decreased by adding HCl, a similar trend in virus adsorp- tion was observed. The decrease in the pH of the solution that was caused by the addition of aluminum chloride was sufficient to explain the observed increase in virus adsorption associated with the addition of aluminum chloride. Adding urea in the absence of salt ions did not have a sig- Measurement of aluminum concentrations. Solutions were analyzed to deter- mine total aluminum contents before and after filtration by workers at the Analytical Research Laboratory of the University of Florida. Contact angle measurements. Contact angles for chloroform on filters were measured as previously described (21). TABLE 2. Effects of 0.1 M MgCl3 and 4 M urea on virus adsorption to microporous filters at pH 7" % Adsorption in the presence of: Buffer containing 4 M urea plus 0.1 M MgCl2 RESULTS The effects of solutions of salts at pH 7 on the adsorption of the viruses studied to the filters depended on the filter type and the salt added (Table 1). In general, addition of salts increased the adsorption of viruses to Millipore filters and interfered with the adsorption to 1MDS filters. Except for X174, the salts did not increase viral adsorption to Whatman filters. Mag- nesium chloride greatly increased the adsorption of poliovirus to Filterite filters; the salts had little or no effect on adsorption of the phages tested to these filters. The effects of buffer and buffer containing a salt (sodium chloride, magnesium chloride, or aluminum chloride) at a con- centration of 0.1 M on adsorption of viruses at pH 3.5 are shown in Table 3. None of the salts affected viral adsorption to Millipore or Whatman filters. More than 95% of the viruses tested adsorbed to Millipore filters, and less than 10% ad- sorbed to Whatman filters under all of the conditions tested; however, the salts interfered with viral adsorption to 1MDS and Filterite filters. The degree of interference depended on the virus and the salt used. Aluminum chloride interfered with adsorption of viruses to 1MDS filters more than magnesium chloride or sodium chloride interfered with such adsorption. Only aluminum chloride interfered significantly with virus ad- sorption to Filterite filters. The effect of the concentration of magnesium chloride on Filter Virus Buffer Buffer containing 4 M urea Millipore HA MS2 PRD-1 8 Ab 6 A 1 B 6 A 3 A 3 A «Χ174 4 A 4 A 2 A Poliovirus 1 3 A 7 A 2 A Mean 5 5 2 Filtrite MS2 6 A 8 A 3 B PRD-1 11 A 6 A 2 B OX174 3 A 3 A 1 A Poliovirus 1 10 A 11 A 10 A Mean 8 7 4 Whatman MS2 18 A 4 B 5 B PRD-1 OX174 7 A 4 A 4 A 5 A 5 A 7 A Poliovirus 1 8 A 4 A 7 A Mean 10 4 6 1MDS MS2 96 A 96 A 6 B PRD-1 97 A 90 A 11 B ΦΧ174 29 A 21 A 10 B Poliovirus 1 79 A 68 A 8 B Mean 75 69 9 a We added approximately 105 PFU of virus to 25-ml portions of buffer, buffer containing 4 M urea, and buffer containing 4 M urea plus 0.1 M MgCl2, and each type of solution was passed through the different types of filters at a rate of 1.5 ml/s. The numbers of viruses in the influent and effluent were measured in order to determine the percentage of adsorption in each case. b Values on the same line followed by the same letter are not significantly different at P = 0.05. Downloaded from https://journals.asm.org/journal/aem on 12 February 2024 by 128.138.65.188. VOL. 66, 2000 VIRUS ADSORPTION TO MICROPOROUS FILTERS 2917 TABLE 3. Effects of salts on virus adsorption to microporous filters at pH 3.5ª % Virus adsorption Filter Virus Buffer containing Buffer 0.1 M NaCl Buffer containing 0.1 M MgCl2 Buffer containing 0.1 M AlCl3 Millipore HA MS2 >99 Ab >99 A >99 A >99 A OX174 98 A >99 A >99 A >99 A Poliovirus 1 >99 A >99 A >99 A >99 A Mean >99 >99 >99 >99 Filtrite MS2 >99 A 98 AB >99 A 96 B OX174 95 A 97 A 98 A 23 B Poliovirus 1 99 A >99 A 97 A 10 B Mean 98 98 98 43 Whatman MS2 3 A 4 A 3 A 4 A OX174 6 A 2 A 2 A 4 A Poliovirus 1 9 A 7 A 5 A 7 A Mean 6 4 3 5 1MDS MS2 95 A 60 B 44 C 5 D OX174 85 A 75 B 73 B 10 C Poliovirus 1 Mean 99 A 95 A 93 A 10 B 93 76 70 14 a We added approximately 105 PFU of virus to 25-ml portions of buffer, buffer containing 0.1 M NaCl, buffer containing 0.1 M MgCl2, and buffer containing 0.1 M AlCl3, and each type of solution was passed through the different types of filters at a rate of 1.5 ml/s. The numbers of viruses in the influent and effluent were measured in order to determine the percentage of adsorption in each case. b Values on the same line followed by the same letter are not significantly different at P = 0.05. nificant effect on viral adsorption to the filters at pH 7 (Table 2). However, viral adsorption was greatly reduced in the pres- ence of both 4 M urea and a salt at a concentration of 0.1 M. We observed a similar effect at pH 3.5; urea alone had little effect on virus adsorption (Table 4). Adding 0.1 M magnesium chloride or 0.1 M aluminum chloride to solutions of urea re- duced the adsorption of both MS2 and poliovirus 1 to the fil- ters tested. Tween 80 at a concentration of 0.1% had the same effect on viral adsorption as 4 M urea had (data not shown). The effects of prefiltering aluminum chloride solutions made with tap water before viruses were added are shown in Table 5. When a 0.0001 M aluminum chloride solution was prepared with tap water at pH 7, viruses added to the solution were removed by a Millipore HA filter. If the aluminum chloride solution was first passed through a 0.2-μm-pore-size Millipore GS filter before the viruses were added, then no significant viral adsorption to Millipore HA filters was observed. The pre- filtering step decreased the concentration of aluminum chlo- TABLE 4. Effects of 0.1 M AlCl3 or 0.1 M MgCl 3 and 4 M urea on virus adsorption to microporous filters at pH 3.5ª % Adsorption in the presence of: Filter Virus Buffer Buffer containing 4 M urea Buffer containing 4 M urea plus 0.1 M MgCl2 Buffer containing 4 M urea plus 0.1 M AlCl3 Millipore HA MS2 >99 Ab +X174 Poliovirus 1 Mean 98 A >99 A 98 A 95 A 15 B 13 B 9 B 7 B >99 A 12 B 15 B 99 Filtrite MS2 >99 A ΦΧ174 95 A Poliovirus 1 99 A Mean 98 12 5225 97 12 12 95 B 14 B 11 B 92 B 7 B 8 B 99 A 13 B 15 B 95 11 11 Whatman MS2 3 A 9 A 11 A 7 A ΦΧ174 6 A 4 A 3 A 6 A Poliovirus 1 9 A 7 A 8 A 4 A Mean 6 7 7 6 1MDS MS2 95 A 95 A 10 B 8 B ΦΧ174 Poliovirus 1 Mean 85 A 69 A 48 B 30 C 99 A 93 99 A 88 50 B 36 10 C 16 Downloaded from https://journals.asm.org/journal/aem on 12 February 2024 by 128.138.65.188. a We added approximately 105 PFU of virus to 25-ml portions of buffer, buffer containing 4 M urea, buffer containing 4 M urea plus 0.1 M MgCl2, and buffer containing 4 M urea plus 0.1 M AlCl3, and each type of solution was passed through the different types of filters at a rate of 1.5 ml/s. The numbers of viruses in the influent and effluent were measured in order to determine the percentage of adsorption in each case. b Values on the same line followed by the same letter are not significantly different at P = 0.05. 2918 LUKASIK ET AL. TABLE 5. Effect of prefiltering the aluminum chloride solutions used in viral adsorption experiments on viral adsorption to Millipore HA filters at pH 7ª Virus MS2 PRD-1 ΦΧ174 Poliovirus 1 Not prefiltered >99 Ab 98 A 95 A >99 A 98 APPL. ENVIRON. MICROBIOL. TABLE 7. Effect of salt type on virus adsorption to 1MDS filters at pH 3.5" % Viral adsorption % Viral adsorption Virus Buffer' Prefiltered Buffer containing Buffer containing Buffer containing 0.1 M AlCl3 0.2 M MgCl2 0.6 M NaCI 13 B MS2 95 Ac 5 B 10 C 13 C 8 B «Χ174 85 A 10 B 24 C 31 C 14 B Poliovirus 1 Mean 99 A 10 B 36 C 20 C 93 8 23 21 16 B 13 Mean a The concentration of aluminum chloride in 100 ml of dechlorinated water containing 105 PFU of virus per ml was adjusted to 0.0001 M. Fifty milliliters was passed through a Millipore HA filter at a rate of 1.5 ml/s. The remaining 50 ml was first passed through a glass fiber prefilter (Millipore GS). This solution was then passed through a Millipore HA filter. In each experiment the numbers of viruses in the influent and effluent were measured, and the corresponding per- centage of adsorption was determined. b Values on the same line followed by different letters are significantly different at P = 0.05. ride from 0.0001 M to less than the detectable level (<0.00003 M). In contrast, no change in the aluminum chloride concen- tration was observed following filtration of 0.0001 M aluminum chloride solutions through the same type of filter at pH 3.5 (where aluminum chloride is more soluble). In order to separate the effects of salt type from the effects of ionic strength, we performed experiments in the presence of added salt at a constant ionic strength. As shown in Table 6, magnesium chloride solutions were better at promoting ad- sorption of MS2 and PRD-1 than sodium chloride solutions at the same ionic strength were. Sodium chloride and magnesium chloride both promoted adsorption of X174 to nitrocellulose filters. Increasing the ionic strength of solutions of magnesium chloride and sodium chloride to the ionic strength of alumi- num chloride decreased the adsorption of viruses to 1MDS filters (Table 7). At a constant ionic strength of 0.6, all of the salts significantly reduced the virus adsorption that was ob- served in solutions containing buffer alone. However, the great- est interference with adsorption was observed with solutions of aluminum chloride. DISCUSSION Based on early studies on the influence of salts on virus adsorption, it was suggested that salts promote virus adsorp- tion to microporous filters by promoting electrostatic interac- TABLE 6. Effect of salt type on virus adsorption to Millipore HA filters at pH 7 0.1 M MgCl2 % Viral adsorption Virus Bufferb Buffer containing Buffer containing 0.3 M NaCl 8 A 99 B PRD-1 6 A 59 B Χ174 4 A 57 B Poliovirus 1 Mean 3 A 5 99 B 79 61 C 3 C 42 B >99 B 51 MS2 a Experiments were performed as described in Table 1, footnote a, except that the ionic strength of the salts was maintained at 0.3. b Values from Table 1. Values on the same line followed by the same letter are not significantly different at P = 0.05. Experiments were performed as described in Table 1, footnote a, except that the ionic strength of the salts was maintained at 0.6. b Values from Table 1. © Values on the same line followed by the same letter are not significantly different at P = 0.05. tions between the viruses and the filters. The possible mecha- nisms that were suggested to explain the observations made were salt bridging and charge neutralization of the filters. It was also suggested that the ability of salts to promote virus adsorption was related to the valence of the cation involved. Trivalent cations (Al³+) were better than divalent cations (Mg2+), which were better than monovalent cations (Na+), at promoting virus adsorption when the cations were used at the same concentration (4, 13, 16, 17, 27, 28). In examining the early studies on the effects of salts on virus adsorption, we found three main problems. These were (i) the role of salts in promoting hydrophobic interactions was not always considered; (ii) the indirect effects of adding salts on the pH values of solutions and flocculation of the salts were not always determined; and (iii) few viruses and few filter types were studied. Below we discuss these problems in relation to our study. Hydrophobic interactions. Previous studies on virus adsorp- tion to microporous filters led to the suggestion that metal chelators could interfere with virus adsorption promoted by salts (14, 16, 17). Later studies showed that chelators, such as the citrate ion, did not elute viruses adsorbed to Millipore HA filters (7). In fact, chelators have been found to promote, ra- ther than interfere with, virus adsorption to microporous filters (6). The study of Farrah (6) and other studies showed that in- creased virus adsorption to certain microporous filters in the presence of cations and anions was influenced by hydrophobic interactions (6, 12, 21). Therefore, the adsorption of MS2 and poliovirus 1 in the presence of salts to filters was best explained by the presence of hydrophobic interactions between the filters and the viruses. The effect of added magnesium chloride on virus adsorption was to strengthen hydrophobic interactions rather than electrostatic interactions (6). In this study, urea had little effect on virus adsorption. This compound did not interfere with or promote adsorption of viruses to the filters tested at pH 7.0 or 3.5. In contrast, it greatly reduced virus adsorption when salts were present. The neutral detergent Tween 80 had an effect similar to that of urea, even though it was used at much lower concentrations. As discussed above, the salts probably promoted hydrophobic interactions and interfered with electrostatic interactions be- tween the viruses and the filters (5, 12, 21). Indirect effects. Adding salts can change the pH of a solution or cause the formation of flocs, or salts can interact with or- ganic material present in the solution. This is especially true for aluminum salts and makes determining the direct role of aluminum ions on virus adsorption difficult. As shown in Fig. 4, the effect of increasing the aluminum chloride concentration on virus adsorption reported by Wallis et al. (28) can be ex- Downloaded from https://journals.asm.org/journal/aem on 12 February 2024 by 128.138.65.188.See Answer
Q15: Ex. 16: Identification of unknown bacteria How are bacteria identified in the lab? Huge machines run hundreds of the same biochemical tests we do in class to identify the kind of bacteria in the sample DNA of unknown pure cultures sequenced Fluorescently labeled ddNTPs T A ddTTP ddATP ddGTP ddCTP T A G DNA template Separate with a gel G A CTG A A G C A C T GAA C T G A A G C T T T G A A G C T G A A G C T A A G CT A G C T G C T Use a sequencing machine GACTGAAGCT Ex. 16: Unknown bacteria Take all you have learned up to this point to identify an unknown sample Each person will get an unknown! This is an individual activity Use skills such as isolation streaking, gram staining, identifying colony and cell morphology Follow the keys in the exercise to build evidence on what your unknown is Summary of results due at the end of the term Possible Bacteria Escherichia coli Citrobacter freundii Bacillus subtilis Bacillus megaterium Bacillus cereus Klebsiella aerogenes Proteus vulgaris Serratia marcescens Day 1 Get your unknown sample-keep track of culture # and any observations throughout the process in table 16.1 Do an isolation streak with your unknown. Streak at least 2 TSA plates Gram stain unknown. Is it a pure or mixed culture? Are cells of similar morphology? Begin doing metabolic tests as you see fit. Day 2 and onward... Observe isolation streaks from last period. Continue metabolic tests. Important to write down interpretations throughout the entire process in table 16.1. Confirm your results as you go./n/nSee Answer
Q16:Lab 2 Writing Assignment Due: Thu Apr 18, 2024 11:59pm Attempt 1 In Progress NEXT UP: Submit Assignment 10 Points Possible Add Commen Unlimited Attempts Allowed ✓ Details Please refer to this Google document describing the Lab 2 "Lab Writing Assignment #1" for instructions. Once finished with your assignment, submit it here to Canvas as a Word document or pdf that includes 1) Your captioned image (= figure (image) + caption) 2) Your compare and contrast (table & paragraph) 3) Your scored grading rubric table Please ask if you have any questions! ✓ View Rubric Ⓡ Σ B hp 31 Submit Assignment Ne Apr 18 2:44/n/n ** This document is being shared as a viewable document only because this document is being used by everyone taking Biology 211 this quarter. Should you wish to answer questions or take notes about this lab, please copy and paste this document into another file and annotate the document there. ** BIOL& 211 | Lab 2 | Compound Microscope and Cellular Diversity Credit: CCO Public Domain Part 1: Concepts of Microscopy Objectives • Learn how to use microscope “field of view” dimensions to estimate the size of objects viewed with the microscope. Understand some essential microscope terminology, including compound (or light) microscope, field of view, depth of field, magnification, contrast, and resolution. INTRODUCTION Humans are visual creatures, obtaining much of our information about the world around us by using our eyes. Not surprisingly, some of the most useful tools in biology are those that allow us to visualize objects, processes, and phenomena. Powerful computers and other recent technologies today allow us to visualize and explore as never before. But even these cannot replace one of the most fundamental tools of biology, the microscope. With the microscope we can see things that are too small for the naked eye. There are many different kinds of microscopes (see your textbook). The one you will familiarize yourself with today is the compound light microscope. In this online lab activity we will explore how to use and care for this most basic of biological tools that has unlocked so many mysteries of the biological world! PRELAB As preparation for the lab: 1. Watch this video on how to use a microscope: https://www.youtube.com/watch?v=xzjowD1KN20 2. Familiarize yourself with the following terms in microscopy: Field of view: Refers to the area you see when you look through the microscope. As you observe a specimen using the three different objective lenses, note how the field of view changes with magnification. • Depth of field: Refers to the vertical distance (thickness or depth) that is in focus at • the same time. The depth of field also changes with magnification. Magnification: The apparent increase in size • Contrast: Refers to the degree of difference between dark and light areas of the • specimen. High contrast is helpful in bringing out details. Resolution: The ability to see two closely spaced objects as separate ** As you go through the cell size estimation activity in the next couple of pages, think about how the above terms are important in generating the images that you see. 1 Activity: Cell Size Estimation In this activity, you'll learn how to use scale bars to calculate the size of specimens visualized with a compound microscope. To start, please watch the following video: https://www.youtube.com/watch?v=E_NiyAt7pRM 1. Determining the size of a red blood cell Observe the image of red blood cells. 50μm Notice that the scale bar says "50µm,” which is 50 micrometers or 0.05 mm. First, estimate how many blood cells could fit end to end along the scale bar. Now, use that estimate and the equation below to calculate the size of an individual blood cell: 0.05 mm (length of scale bar) Number of cells that fit along scale bar Your calculations: 2 _mm (diameter of 1 cell) 2. Determining the size of a Volvox colony Observe the image of Volvox globator. 150μm Notice that the scale bar says “150 µm,” which is 150 micrometers or 0.15 mm. Estimate how many of the Volvox can fit along the scale bar. Does one entire Volvox fit, or does only part of one fit on the scale bar? Show your work below. Your calculations (include the correct equation for this problem, as modeled in the first problem): 3 3. Determining the diameter of a sea urchin sperm Observe the image of sea urchin sperm. 50μm Notice that the scale bar is 50 μm. Determine the diameter of the head (round portion) of a sea urchin sperm. Your calculations: 4/n INSTRUCTIONS FILE Here you have to make the both lab report as they are dependent In case you have to choose anything you will 1 choose all bacteria and everything required by yourselvesSee Answer
Q17:Build a graph that shows the average total cells per image and the average percent trypan-positive cells vs. treatment. Your column graph should have a title, y-axis and x-axis titles, each column needs to have a label. You must add standard deviation to each bar. See Appendix on Excel on how to do this. Save this graph as an image called percent trypan positive as a .jpg or .png./ntotal Treatment | Average, number of cells Average % trypan + cells. HPMI 24 Tween-20 29 0.5% Tween-20 17 3 0.1% Drug G 55 5 Drug K 24 19 0 10See Answer
Q18: Results to use for your Gram Stain Data Sheet Use for #8 on your Gram Stain Data Sheet Use for #17 on your Gram Stain Data Sheet Note: The answers to question #1 must be written in the format shown on the photo; after the equal sign the answer is either pink, purple or colorless. Name Date Lab Section I was present and performed this exercise (initials) Gram Stain OBSERVATIONS AND INTERPRETATIONS 1 Record your observations in the table below. Use separate lines for different organisms found in the Gram stain of your gumiline. Include a drawing of your own epithelial cells. #8 #17 Organism or Source Cellular Morphology and Arrangement Cell include a detailed sketch of a few representative cells) Dimensions DATA SHEET 3-6 Color MCB2010Lab Gram Reaction 139 19 QUESTIONS (1 Predict the effect on Gram-positive and Gram-negative cells of the following "mistakes" made when performing a Gram stain. Consider each mistake independently. Pink, PURPLE or Colorless a. Failure to add the iodine. Gr + Gr b. Failure to apply the decolorizer. Gr + 65 c. Failure to apply the safranin. 6r+ 6r. d. Reversal of crystal violet and safranin stains. 6r+ 2)Both crystal violet and safranin are basic stains and may be used to do simple stains on Gram-positive and Gram-negative cells. This being the case, explain how they end up staining Gram-positive and Gram-negative cells differently in the Gram stain. 3 If you saw large, eukaryotic cells in the preparation made from your gumline, they were most likely your own epithelial cells. Are you Gram-positive or Gram-negative? (You can make a good guess about this even if you didn't see your cells.) 4 One of your lab partners has followed the recommended procedure of running Gram-positive and Gram-negati control organisms on her Gram stain of an unknown species. Her choices of controls were Escherichia coli an Bacillus subtilis. She tries several times and each time concludes she is decolorizing too long because both Results to use for your Acid Fast Data Sheet 1 Use for Mycobacteria on your Acid Fast Data Sheet Use for Enterococcus on your Acid Fast Data Sheet pro Namo Date Lab Section I was present and performed this exercise (initials) 1 Record your observations in the table below. Organism Enterococcus my bactria Acid-Fast Stains OBSERVATIONS AND INTERPRETATIONS Staining Cellular Morphology and Arrangement Method (include a detailed sketch PROK of a few representative cells) к FERIE K Cell Dimensions Color DATA SHEET 3-7 Acid-Fast Reaction (+/-)See Answer
Q19: Ex. 14 Lactic Acid Fermentation Introduction Lactic acid fermentation has been used by humankind in food production for thousands of years. Lactobacillus, Leuconostoc, Streptococcus, and Bifidobacterium are common bacterial genera that can ferment simple sugars in food to produce lactic acid and other organic acids, influencing the flavor, nutritional content, and preservation of the foods. Fermentation is a type of metabolism the occurs in the absence of oxygen. An anoxic environment helps prevent growth of some harmful microbes that could contaminate foods, and the acidic byproducts produced during fermentation also have preservative properties. Additional ingredients are often added during fermentation that can provide seasoning and also help ensure that the culturing process is biased towards growth of fermentative microbes, and that the growth of potentially harmful contaminant microbes is prevented. Sauerkraut is a fermented food produced by immersing cabbage in salt water, and then then allowing fermentative growth of bacteria in anoxic conditions. The presence of the salt and the anoxic environment help limit the growth of undesirable bacteria and fungi. The fermentation of sauerkraut occurs through growth of a succession of microorganisms. The first colonizers are only slightly tolerant of low pH and lactic acid, and as they grow, residual oxygen is consumed and acid is produced, leading to a reduction in solution pH. As the pH drops, other bacteria that are more acid tolerant become dominant in the culture (for example, Leuconostoc mesenteroides and Lactobacillus sp.). Leuconostoc cells are described as heterolactic bacteria because they produce approximately equal amounts of lactic acid, ethanol, and CO2. Eventually, increasing acidity will inhibit growth of Leuconostoc as well, and other fermenters such as Lactobacillus sp. will begin to predominate in the sauerkraut culture. Lactobacilli are described as homolactic bacteria because they produce lactic acid as their main fermentation byproduct. Eventually, enough lactic acid from bacterial fermentation accumulates to cause full inhibition of bacterial growth, thereby allowing preservation of the sauerkraut for a long time. Preserved foods like sauerkraut were especially valuable during wintertime, when fresh produce was hard to come by. Learning Objectives Be able to describe how Sauerkraut ferments over time Why is sauerkraut prepared with salt and kept in an anoxic environment? How does pH change, and how does this influence the succession of bacterial species? - - - Be able to describe homolactic vs heterolactic fermentation Lab Period 1 (Set up a sauerkraut culture) Materials and Supplies One deMan-Rogosa-Sharpe (MRS) agar plate: selective for Lactobacillus One Tomato Juice (TJ) agar plate: selective for Leuconostoc Anaerobic jars, pH paper, hot plate, aluminum foil, tablespoon, cutting board, knife. - Green cabbage, table salt (sodium chloride), large plastic container (~2–4 Liters) to contain the cabbage mixture. Plastic bags, to line the cabbage container. Ziplock bags, to contain macerated cabbage, water, and salt. When sealing the bag, the air in the bag should be minimized to help reduce the amount of oxygen present for the fermentation process. Balance, weighing dishes, Bunsen burner, striker, inoculating loop. Procedure 1) The sauerkraut will be prepared by your TA, with some help of some volunteers who are comfortable. Chop the cabbage into even, small pieces and put into zip-lock bags. Make sure that the zip-lock bag is open, on the scale, and tared to get an accurate reading of the weight. The lab scales can only handle up to 400 grams of weight, so don't force them to go over. Make enough bags of cabbage for at least each bench to get one and label the weight on the front of the bag. 2) After making the bags of cabbage, pass them out to the benches and start adding the salt. This style of fermentation requires 3 % (by weight) table salt to be added to the bag of cabbage. Calculate the proper amount of salt for the weight specifically written on your bag of cabbage. 3) Once you have added salt, massage and mash the cabbage until it is wilted and there is a significant amount of cabbage juice in the bag (be careful not to break the bag). This maceration process can take up to 30 minutes. 4) Once you judge that the cabbage is fully macerated, use a transfer pipette to collect about 1mL of the liquid, and add to a microcentrifuge tube. 5) Add your cabbage to the communal cabbage bucket and toss the used ziplock bag into the biohazard waste. 6) Using your centrifuge tube of cabbage juice, and correct streaking technique, streak the MRS and TJ plates. Note: MRS agar is a green/brown color and TJ agar is a dark red color. 7) Measure the pH of the cabbage juice and record in Table 14.1. This is the initial measurement for comparison to see how pH changes as the bacteria colonize the sauerkraut culture. 8) Using a loop, transfer a drop of cabbage juice to a microscope slide, and prepare a wet mount for viewing with the microscope. See Ex. 6 if you need to refresh your memory of what a wet mount is and how it is prepared. See Ex. 5 if you need a refresher on how to correctly use the microscope. 9) Write down your results in Table 14.3. Keep in mind that the sauerkraut hasn't had much time to begin the fermentation process, so consider how this may affect your observations, and predict how these observations are likely to change as the fermentation process progresses over the coming days. 10) Incubate the MRS and TJ plate in your lab section's anaerobic jar until the next lab session. 11) Your TA will place some zip-lock bags of water on top of the sauerkraut to keep as much oxygen out as possible during the fermentation process. Lab Period 2 (observations of sauerkraut fermentation) Materials and Supplies One MRS, one TJ agar plate. pH paper, micropipettes, Bunsen burner, striker, inoculating loop. Reagents for Gram staining procedure. Optical microscope with phase contrast, microscope slides, coverslips. Procedure for observing results of Lab 1 sauerkraut fermentation 1) Observe the growth on the TJ and MRS streak plates from the previous lab. Record observations (growth, colony morphology, density) in Table 14.2. Consider the reasons for growth, or lack thereof. - - 2) If you observe colonies on the plates, make wet mount slides, and also perform a Gram stain, and observe them using the microscope. If no growth occurred, skip to step 7). 3) Making wet mounts or gram stains from colonies is different from liquid cultures, because plate cultures contain a greater density of cells, requiring dilution. Start by using adding a drop of water to the slide (use the DI water from the Gram stain kit). 4) Sterilize the inoculating loop, let it cool, and then pick up a small part of a colony from the most dominant colony type on one of the culture plates. Spread the microbes in the in the water on the slide, and form a smear. Do not use an excessive amount of the colony, or the cells will be too dense to allow good visualization of individual cells under the microscope. 5) For each colony type, use this technique to make one slide for a typical wet mount (adding a coverslip to the smear), and one slide smear that you will allow to air dry for Gram staining. 6) Prepare and the observe the Gram stained slides by microscopy. Note that Leuconostoc species are Gram positive cocci that often form chains, while Lactobacillus species are Gram positive bacilli that often form chains. Make general observations, and keep in mind that it is not possible to definitively identify bacterial species from microscopy alone. 7) Record your observartions in Table 14.2, 14.3, and 14.4. Dispose of the plates from last class into the biohazard bin before moving on. 8) Check on the class sauerkraut culture to see how it is changing. As in the previous lab session, use a transfer pipette to collect about 1 mL of the fermented liquid to place into a centrifuge tube. 9) Streak some of the culture on fresh MRS and TJ plates. Incubate the plates in the anaerobic jar again until next class. 10) Measure the pH of the sauerkraut liquid, and record the results in Table 14.1. Lab Period 3 (observations of sauerkraut fermentation) Materials and Supplies - 1 MRS agar plate and 1 Tomato Juice (TJ) agar plate pH paper, centrifuge tubes, Gram staining supplies Procedure 1) Observe the streak plates from the previous lab and note differences. Again, if you have any viable colonies, prepare wet mounts and Gram stains of representative colonies and record your results in Tables 14.2, 14.3, and 14.4. Dispose of your plates from last class before moving on. 2) Use a transfer pipette to collect a sample of sauerkraut liquid to place into a centrifuge tube. Does the sauerkraut look different this time? Is it smelling different? 3) Remove a sample with your loop and streak on MRS and TJ agars. Incubate the plates in the anaerobic jar until next class. 4) Record the pH of the liquid (Table 14.1). A change in pH towards more acidic indicates that fermentation has occurred and the bacteria are producing acid. Were there any bubbles in the fermented liquid? If so, what are they from? Lab Period 4 (observing sauerkraut) Procedure 1) Examine your plates streaked from the sauerkraut culture in the previous lab session. Record results in Table 14.2. 2) Prepare a wet mount and Gram stain from colonies on each plate. Measure the pH of the sauerkraut fermentation. Record all results in Tables 14.1, 14.3, and 14.4. 3) Dispose of your plates from last class. 4) Make any final observations of how the sauerkraut has changed during the course of the fermentation./nSee Answer
Q20:- To understand the importance of identification of bacteria and its relevance to applied microbiology today. - To be able to use the phenotypic tests learnt in previous practical sessions to identify bacterial isolates to species level using the RMIT identification tables. -To understand the basis of the biochemical reactions tests and what they tell us about the metabolism of the investigated bacterium.See Answer

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