3910_Assignment1_2010 - BioMi 3910 Advanced Microbiology...

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BioMi 3910 Advanced Microbiology Laboratory For Friday, Aug 27 Answer the following questions. .. based on your reading assignments. Also know the “take home message” of each paper. What were the major points presented by the authors? What methods were used? 1. DNA complexity studies have provided estimates of microbial “genome equivalents” in complex environmental samples. Within an order of magnitude, how many different microbial genomes may be found in natural soils that are rich in organic matter but that have not been used for agricultural purposes? 2. Briefly describe one factor that may impact bacterial diversity in an environment. 3. What are “r-strategists’? 4. From the PNAS paper by Whitman et al., find the following values the average number of bacteria plus archaeal cells found in 1 ml of fresh water from a lake the density of microbes in the human colon the estimated total number of all ruminal microbes in all of the cows in the world 5. How many microbes (bacteria plus archaea) are there in the world? 6. Based on this estimate Whitman, Coleman a Wiebe make some surprising conclusions about life on this planet, describe the one that most impresses you! 1
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BioMi 3910 Advanced Microbiology Laboratory Answer the following questions. .. turn in on Monday, Aug 30. 1. Did PBS or water recover more CFUs? Answer: PBS. P BS contains phosphate and NaCl, and basic media culture. Most system need ionic concentration in the environment because cell membrane requires an ionic environment for exchange. Distilled water does not provide the best environment and the ions needed. 2. How might incubation temperature influence plate counts? Answer: temperature is an important factor in bacterial growth. Different bacteria from different environment prefer to live in at certain temperature range. Therefore, incubating the plate at different temperatures will enrich for bacteria, lowering or increasing the plate counts. A drawback of this is that temperature may enrich for bacteria that would otherwise not grow in the natural environment. 3. What is tryptone? – A medley of peptides formed by the digestion of casein and provides essential amino acids (nitrogen) for bacterial growth. What is peptone? – Enzymatic digest of animal proteins. It contains small peptides, and some fats, metals, salts, vitamins. For bacterial growth, it supplies amino acids, a Nitrogen source. In mediums, it can be used to complement peptone by providing minerals, phosphates, energy sources and those essential factors that are not in peptone. What is beef extract???
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3910_Assignment1_2010 - BioMi 3910 Advanced Microbiology...

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