Abstract
The capability of osmoadaptation is a prerequisite of organisms that live in an environment with changing salinities. Halobacillus halophilus is a moderately halophilic bacterium that grows between 0.4 and 3 M NaCl by accumulating both chloride and compatible solutes as osmolytes. Chloride is absolutely essential for growth and, moreover, was shown to modulate gene expression and activity of enzymes involved in osmoadaptation. The synthesis of different compatible solutes is strictly salinity- and growth phase-dependent. This unique hybrid strategy of H. halophilus will be reviewed here taking into account the recently published genome sequence. Based on identified genes we will speculate about possible scenarios of the synthesis of compatible solutes and the uptake of potassium ion which would complete our knowledge of the fine-tuned osmoregulation and intracellular osmolyte balance in H. halophilus.
Highlights
Salt marshes are costal ecosystems in the upper intertidal zone between land and open sea water.Soil and water of this area face drastic changes in salinities since the land is regularly flooded by tides.In addition, water evaporates in summer leading to dryness and extremely high salinities of up to 3 MNaCl, while extensive rainfalls can decrease the salinity to fresh water concentrations
Transcription analyses after an osmotic upshock from 0.8 to 2 M NaCl have shown that one of the putative glutamate dehydrogenase genes was induced and the mRNA level increased within 1.5 hours to about four-fold compared to the level before the upshock
To resolve the time-dependent kinetics of ectoine production H. halophilus cells were subjected to an osmotic upshock from 0.8 to 2.0 M NaCl and the biosynthesis of ectoine was measured at the levels of transcription, translation and solute accumulation
Summary
Salt marshes are costal ecosystems in the upper intertidal zone between land and open sea water. Soil and water of this area face drastic changes in salinities since the land is regularly flooded by tides. NaCl, while extensive rainfalls can decrease the salinity to fresh water concentrations. Life 2013, 3 all kingdoms of life that live in these areas have to adapt to such changing salinities by various strategies of osmoadaptation. A well-studied model organism for osmoadaptation is the rod-shaped, endospore-forming, Gram-positive bacterium Halobacillus halophilus, which was isolated from a salt marsh on the North. H. halophilus grows optimally between 0.5 and 2.0 M NaCl but can tolerate NaCl concentrations of up to 3.0 M NaCl with a growth rate of 38% of the optimum [3]. H. halophilus have been studied extensively in the past decades demonstrating a highly salinity- and growth phase-dependent adaption. This review will summarize the molecular mechanisms of osmoadaption in context of the recently published genome
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
