Genomic exploration of bacterial habitat adaptation

In this study we adopted a cross-habitat, comparative genomic approach to identify genetic markers of habitat adaptation in bacterial populations from human gut, marine and soil environments. Although humans depend heavily on microbial activity in these ecosystems, these environments are very different from a microorganism?s perspective. We hypothesized that genetic markers characteristic of one of these three environments would be indicative of the strongest drivers of selection in these environments. Many of the discriminating genetic markers for a given environment mapped well onto environmental characteristics of that environment. For example, bacteria isolated from the human gut environment tended to have the least functional diversity and lacked pathways for amino acid biosynthesis and DNA repair. In contrast, soil and marine bacterial genomes had relatively high functional diversity and possessed abundant pathways for energy production, stress response, and response to a variable environment.