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MGY377H1 Midterm: Study notes for midterm

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redtermite204
24 Dec 2011
School
UTSG
Department
Molecular Genetics and Microbiology
Course
MGY377H1
Professor
William Navarre

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Document Summary

Chemostat is continuous culture device density adjust by changing nutrient media; canot control both growth rate and population density together; 10 000 left if start with 1 000 000 and heat for 2d d depends on temperature. Bacteria live in social environment interact with one another. No function in lab when grown in monoculture bacteria do not live in monoculture multiple species living together. Studying something in lab condition can give biased point of view disgarding things as irrevevlant that are very important in natural environment new era of genomics trying to break out of this monoculture viewpoint. Make own adhesions, polysacchardies, matrix not passive sticking to surface. Most bacteria growing on rocks, toilets, teeth surfaces. Community oriented and swimming lifestyle two different. Decision made by planktonic bacteria swimming around, lands on surfce, gene expression changes, makes decision to grow differently. Fruiting bodies made decision to act as group bacteria have this capacity. Pipe corrosion and clogged pipes bacteria stick.

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Related Questions

1. Many bacteria exist in biofilms in nature. Based on the information in the passage and in the chapter, is it possible to create a pure culture of a species that normally exists in biofilms?

Select the best answer.

A) Yes, because many species can have planktonic growth or live within a biofilm, and a biofilm can contain a single species.
B) Yes, because bacteria are most commonly found in sessile forms and a biofilm contains sessile bacteria.
C) No, because a pure culture by definition must grow in medium and would not be able to form a biofilm.

D) No, because biofilms always contain many species of bacteria and a pure culture does not.

2. The introductory passage described a consortium consisting of ANME and a sulfur oxidizing bacteria. Which of the following would be important considerations in choosing the best technique to determine the number of living cells in a culture of the consortium?

Select the best answer.

A) Some fluorescent stains react differently based upon whether a cell has an intact cell membrane.
B) Phylogenetic stains can distinguish between species of Bacteria and species of Archaea.
C) DAPI can be used to stain DNA.
D) Cells present in low concentrations can be counted using microscopic cell counts, but they must be concentrated first.
E) Small cells are more difficult to see when doing microscopic cell counts.

3. Quinones are one type of molecule that bacteria use to communicate with one another. This paper describes an example of Streptococcus agalactiae switching metabolism from aerobic to anaerobic after quinone signaling. From what you know about biofilms, what type of metabolic shifts might be happening with quinone signaling? List 3 possible outcomes related to biofilm formation.

4. (4 points) What are short-chain fatty acids, and how do they differ from bacteriocins and quinones?

5. (5 points) Biofilms are formed in many different environments, with varying nutrient contents. As you read in the paper, biofilm formation can be triggered in low nutrient environments. In lab you tested the ability of your Pseudomonas soil isolate to form a biofilm in minimal media, but soils typically are considered nutrient rich. What are some other advantages of biofilm formation in soil? (Hint: think about the environmental conditions such as moisture, pH, temperature and how they may change).

How would you us the media to help identify S. Marcescens and E. coli if they were growing together in a tube of nutrient broth? Which technique would you use to help you distinguished between colonies of the two bacteria? If you were trying to obtain pure cultures of these bacteria from the tube of nutrient broth what selective and differential media might you use and how would you separate and purify the two cultures of bacteria?

E. aerogenes on the selective and differential media, describe how you might use this information to predict the Gram reaction for this bacterium?

How would you differentiate between Edwardsiella tarda and Klebsiella pneumoniae? Describe the expected growth outcome and appearance on the media that you choose.