Physiology of Halomonas Elongata in Different NaCl Concentrations

Abstract

Several recent physiological studies of Halomonas elongata have shown that this bacterium makes a variety of physiological changes in response to the NaCl concentration of its growth medium. This previous research has indicated that H. elongata responds to NaCl by tightening its cell wall structure and shifting from a hydrophobic cell surface to one with a more hydrophilic character. In addition, experiments on membrane transport and uptake have shown that the cell permeases adapt to the specific NaCl concentration in which the organisms are grown.

Further examination of this bacterium has centered on specific fatty acid and protein changes. The data produced from these studies show a variety of salt related variations. These changes include an increase in the total fatty acid content of the cells as well as differences in the type and proportion of fatty acids present. Cells grown in high salts possess increased saturated and hydroxy fatty acids. The types of changes noted are consistent with previous data indicating an overall tightening of the cell walls in response to NaCl.

A concomittant study of the protein profiles of this bacterium has shown that the organism also produces various salt related proteins. Whole cell profiles have shown that low salt grown cells possess several unique protein groups which appear to be either absent or modified in high salt grown cells. Preliminary immunological examination indicates that at least some of these altered proteins are present on the outer surface of the cells. Altogether the data indicate that H. elongata maintains its salt tolerance through the interaction of a number of cell systems.