Biology of Moderately Halophilic Aerobic Bacteria

Abstract

SUMMARY The moderately halophilic heterotrophic aerobic bacteria form a diverse group of microorganisms. The property of halophilism is widespread within the bacterial domain. Bacterial halophiles are abundant in environments such as salt lakes, saline soils, and salted food products. Most species keep their intracellular ionic concentrations at low levels while synthesizing or accumulating organic solutes to provide osmotic equilibrium of the cytoplasm with the surrounding medium. Complex mechanisms of adjustment of the intracellular environments and the properties of the cytoplasmic membrane enable rapid adaptation to changes in the salt concentration of the environment. Approaches to the study of genetic processes have recently been developed for several moderate halophiles, opening the way toward an understanding of haloadaptation at the molecular level. The new information obtained is also expected to contribute to the development of novel biotechnological uses for these organisms.

Trehalose, a temperature‐ and salt‐induced solute with implications in pathobiology of Acinetobacter baumannii

“…The accumulation of compatible solutes is a strategy to combat osmotic stress widespread in all domains of life (Ventosa et al, 1998;Roessler and M€ uller, 2001). The aim of this study was the identification of compatible solutes accumulated in response to salt stress in the human pathogen A. baumannii.…”

“…These solutes are compatible with the cells metabolism and are either synthesized de novo or taken up from the environment. Uptake is preferred over de novo synthesis for energetic reasons and uptake of solutes usually represses synthesis of genes required for de novo synthesis (Kempf and Bremer, 1998;Ventosa et al, 1998;Oren, 1999). Even though under desiccation bacteria have to deal with substantially lower water activities than under osmotic stress, the responses to both kind of stresses have a huge overlap, which includes the accumulation of compatible solutes (Ramos et al, 2001;Katoh et al, 2004;LeBlanc et al, 2008;Reina-Bueno et al, 2012;Finn et al, 2013).…”

Osmoadaptation in bacteria and archaea: common principles and differences

“…However, this does not, per se, rule out a function as a compatible solute. Another widespread compatible solute that is synthesized by nearly all heterotrophic, halotolerant bacteria is the zwitterionic cyclic amino acid derivative ectoine (Severin et al, 1992;Ventosa et al, 1998). In contrast, ectoine has not yet been detected in archaea.…”

Glycine betaine metabolism in the acetogenic bacterium Acetobacterium woodii

“…Carnitine is widespread in eukaryotes where it is essential for fatty acid metabolism (Longo et al, 2016). Glycine betaine (GB, N,N,N-trimethylglycine) is probably the most widespread quarternary amine found in living cells (Rhodes and Hanson, 1993;Galinski, 1995;Ventosa et al, 1998;Roeßler and Müller, 2001). It is produced by many plants and algae in response to increasing osmolarities (Rhodes and Hanson, 1993;Sakamoto and Murata, 2002).…”