Chapter 5:The Power of Bacteria
- More and more research groups are seeking to show that changes in the microbiota of a particular site are involved in diseases such as periodontal disease, inflammatory bowel disease, and premature birth. Critics object that showing an association is not the same as demonstrating cause and effect. In the case of the obesity study, scientists tried to do this by inoculating germ free mice with different variations of the microbiota. Clearly, this would not be possible in humans. How might you prove cause and effect in humans?
- Members of the microbiota cause some quite serious diseases. How could a bacterium that normally lives in a beneficial or neutral association with its human host cause serious disease?
- The assertion is made in this chapter that scientists now believe that transfer of DNA by conjugation in the colon is occurring across species and genus lines. Suppose you found the same type of antibiotic-resistance gene in members of two different genera. What criteria might you use to show that the gene was transferred horizontally? How might you suspect that the gene was transferred by conjugation?
- PCR combined with sequencing can provide a quick identification of bacteria. What are the limitations of this approach?