Halophilic bacteria and their compatible solutes – osmoregulation and potential applications

Halophilic bacteria grow over an extended range of salt concentrations. Their metabolic patterns are distinct compared to their terrestrial counterparts and obligate halophiles. The possibility of rapid adjustment to changes in the external salt concentration makes them potential candidates for bioprocessing. Halophilic bacteria produce enzymes, metabolites, solutes, exopolysaccharides and pigments which have high commercial value. However, compared to the obligate halophilic archaea, they have been less studied with only a few reports available on designing the production processes. Compatible solutes are the highly soluble, low-molecular weight organic compounds that make halophilic bacteria versatile in their adaptation to salinity. Halophilic bacteria either take in the solutes from the medium or synthesize them de novo. Compatible solutes include amino acids, carbohydrates or their derivatives, sugars and polyols. In addition to their stabilizing effects, they offer a multitude of physiological and potential biotechnological applications ranging from stabilizers of biomolecules, stress-protective agents to therapeutic agents and cosmetic actives. Exploring the significant applications of compatible solutes could be an attractive proposition towards commercialization. Moreover, it would enlighten the bases of adaptations of moderately halophilic bacteria.