Microbial Adaptation to Saline Environments: Lessons from the Genomes of Natranaerobius thermophilus and Halobacillus halophilus
Noha M. Mesbah, Inga Häänelt, Baisuo Zhao and Volker Müller
from: Halophiles: Genetics and Genomes (Edited by: R. Thane Papke and Aharon Oren). Caister Academic Press, U.K. (2014)
The ability of extremophiles to survive and multiply under extreme conditions is of great importance for microbial physiology, evolution and industry. Whole genome sequencing has provided significant insight into mechanisms used by extremophiles for adaptation to extreme environments. This chapter reviews the current knowledge on the adaptation of two halophiles, the anaerobic alkalithermophilic Natranaerobius thermophilus, and the aerobic Halobacillus halophilus, to their extreme environments, with emphasis on traits delineated from their genome sequences. N. thermophilus and H. halophilus have developed different mechanisms for adaptation to their extreme environments. N. thermophilus faces multiple extremes and consequently employs different and diverse adaptive mechanisms, including accumulation of compatible solutes to counteract high salinity, multiple cation/proton antiporters for intracellular pH and ion regulation and changing intracellular amino acid content in response to high temperature. H. halophilus faces predominantly salt stress and has developed a hybrid strategy for adaptation involving accumulation of a mixture of compatible solutes in addition to accumulation of molar concentrations of chloride and probably potassium inside its cells. Intracellular solute composition in H. halophilus is strictly regulated to adjust to changing extracellular osmolarity. Genomic diversity of N. thermophilus indicates the presence of complex regulatory mechanisms necessary for survival under multiple extreme conditions read more ...