How do Microbes Adapt to Diverse Environments?


Earth’s microbes live in staggeringly diverse environments, colonizing habitats with extremes of temperature, pH, salt concentration, or presence of toxic compounds. Archaea, a domain of single-celled microbes sharing traits with bacteria and simple eukaryotes, are well known for their ability to thrive in harsh environments. How this impressive adaptive capability is achieved has remained a mystery. Now, a team of investigators at the Institute for Systems Biology has completed a groundbreaking study on the role of gene regulation in environmental niche adaptation by Halobacterium salinarum, an archaeal microbe that grows in high salt environments. Using a combination of comparative genomics and hypothesis-driven molecular biology experiments, the team found that a specific class of regulatory genes had been duplicated during the archaea’s evolution and controls a nested set of “niche adaptation programs.” These programs control cascades of gene expression essential for adaptation to particular environments. Diversification of these control elements has resulted in a “division of labor” such that overlapping regulatory networks flexibly balance large-scale functional shifts under changing conditions, where rapid adaptation increases fitness. Describing mechanisms that control niche adaptation in microbes allows us to better understand how microbial communities function in natural environments, and provides an intriguing glimpse into fundamental design rules governing biological systems.


Turkarslan, S., D. J. Reiss, G. Gibbins, W. L. Su, M. Pan, J. C. Bare, C. L. Plaisier, and N. S. Baliga. 2011. “Niche Adaptation by Expansion and Reprogramming of General Transcription Factors,” Molecular Systems Biology 7, Article 554. DOI:10.1038/msb.2011.87.