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BISC209/F13: Lab2: Difference between revisions
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→LAB 2: Enumerating Microbial Members & Isolating Bacterial Members of a Soil Community
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==LAB 2: Enumerating Microbial Members & Isolating Bacterial Members of a Soil Community== | ==LAB 2: Enumerating Microbial Members & Isolating Bacterial Members of a Soil Community== | ||
Today you will complete your first investigative goal in our semester long project: assessing abundance of a soil microbial community by enumerating its microbes by two methods, one culture dependent and one culture independent. Today you will also continue acquiring and practicing skills used by working microbiologists. | Today you will complete your first investigative goal in our semester long project: assessing abundance of a soil microbial community by enumerating its microbes by two methods, one culture dependent and one culture independent. Today you will also continue acquiring and practicing skills used by working microbiologists. The results of the fluorescent DNA stain are available and your plate counts are ready to assess. In addition, you will continue to isolate a few bacteria of interest from your soil community in order to show evidence for richness (diversity) and potential for co-operative and competitive behaviors among community members. Next week we will begin testing the whole soil microbial community : a culture-dependent assessment of carbon source utilization diversity. | ||
==Background to Abundance Testing: The Great Plate Count Anomaly== | ==Background to Abundance Testing: The Great Plate Count Anomaly== | ||
Advances in molecular tools for gene sequencing and in other types of microorganism identification have dramatically expanded our knowledge of the contribution of microbes in their (and our) environment. It is estimated that 99.9% of microbes are "unculturable" - that is, currently not able to be cultured by traditional methods! The large number of these uncultured bacteria are responsible for the, so-called, "Great Plate Count Anomaly": the recognition that many more bacteria are present than appear as colonies on agar plates. Culture-independent estimates of the number of bacteria in a gram of soil are 10<sup>9</sup> - this is several hundred to 9,000 ''orders of magnitude'' greater than the number derived from culture-dependent methods. It has been speculated that there might be 10 billion species of bacteria on Earth! | Advances in molecular tools for gene sequencing and in other types of microorganism identification have dramatically expanded our knowledge of the contribution of microbes in their (and our) environment. It is estimated that 99.9% of microbes are "unculturable" - that is, currently not able to be cultured by traditional methods! The large number of these uncultured bacteria are responsible for the, so-called, "Great Plate Count Anomaly": the recognition that many more bacteria are present than appear as colonies on agar plates. Culture-independent estimates of the number of bacteria in a gram of soil are 10<sup>9</sup> - this is several hundred to 9,000 ''orders of magnitude'' greater than the number derived from culture-dependent methods. It has been speculated that there might be 10 billion species of bacteria on Earth! | ||
