Osmoadaptation in halophilic bacteria and archaea

Abstract

environments shows a great adaptation ability to grow under a wide range of salt concentrations. Halophiles are salt loving organisms that grow in salt affected environments and can tolerate a wide range of salt concentrations. According to their salt requirements, they can be categorized into slight, moderate and extreme halophiles. These organisms have a unique ability to survive and grow at high salt concentration and thus could serve as tremendous model systems to understand the molecular basis of high salt adaptation. The physiology of the halophiles is affected by change in salt concentration, pH, growth temperature and nature of available nutrients. Halophilic bacteria and archaea have evolved two strategies to deal with high osmotic stress. Most of the bacteria use ‘compatible solute strategy’ in which they accumulate different organic compounds like proline, ectoine, glycine betaine and glutamine. Halophilic archaea and anaerobic bacteria cope with high salt stress by ‘salt in strategy’ in which they maintain their internal environment by accumulation of high concentration KCl ions.