Steven Finkel, University of Southern California
Bacteria can survive long periods of incubation in very low nutrient environments during long-term stationary phase. For example, populations of E. coli have been maintained for years without the addition of nutrients, leading to highly dynamic communities of microbes. One of the key changes observed is the expression of the growth advantage in stationary phase, or GASP, phenotype, which is manifested by the appearance of mutants with significant fitness advantages in the population. We are applying genetic and large-scale genomic approaches to define both the extent of the genetic diversity appearing in evolving populations, as well as the mechanisms underlying survival mechanisms that appear to be under positive selection. We are also probing the effects of specific environmental conditions on the mode and tempo of evolution in our laboratory microcosms.