OOS 72-3
Microbial life histories
Although most microbes have the capacity for rapid reproduction, this capacity is seldom harnessed in nature due to resource limitation. In resource-limited and spatially structured environments, selection should favor microbes that are able to use resources most efficiently, that is, microbes that produce the most progeny per unit of resource consumed. A systematic framework for classifying and predicting these life histories of diverse microbes has not been available. The goal of our research is to create a framework for describing and predicting microbial life histories.
Results/Conclusions
We have found that the number of ribosomal RNA (rrn) operons in bacterial genomes reflects bacterial life history spectrum, effectively collapsing multivariate life history traits onto a single axis. Maximum growth rate doubles when there is a doubling in the number of rrn operons and the efficiency with which heterotrophic bacteria use carbon is inversely related to rrn copy number. We have also found support for increased genome streamlining and autotrophic metabolism in low rrn copy number bacteria and a tendency for chemotaxis in high rrn copy number bacteria. We are currently investigating the distribution of orthologous gene content among thousands of sequenced bacteria. A conceptual model proposing innate differences in ife histories among oligotrophic and copiotrophic microbes will also be presented.