Characterization Surface Glycopolymers from Halophilic Gram-Negative Bacteria Chromohalobacter salexigens 1QL3 and Halomonas ventosae S5(2)
Extracellular and membrane polysaccharides of halophilic bacteria arouse the interest of researchers as promising biopolymers involved in adaptation and maintenance of normal physiology of microorganisms in saline environments that accompany many biotechnological processes. This work aimed at structural characteristic of surface glycopolymers of halophilic Gram-negative bacteria isolated from the salt samples of the lakes Qarun (Egypt) and Elton (Russia) – strains Chromohalobacter salexigens EG1QL3 and Halomonas ventosae RU5S2EL, respectively. The strains were cultured in a liquid S-G medium. Exopolysaccharides (EPS) were precipitated from the culture liquid with ethanol and fractionated by gel-permeation chromatography. Lipopolysaccharides (LPS) were extracted from dry biomass by Westphal method. Biopolymer composition of the LPS, fatty acid composition of lipids A, and the monosaccharide composition of the EPS and LPS were determined. It was found that C. salexigens EG1QL3 and H. ventosae RU5S2EL produce EPS with a yield of 11.5 and 3 g/L, respectively. The EPS of H. ventosae RU5S2EL is a mixture of the heteropolysaccharides from rhamnose, mannose and glucose, while C. salexigens EG1QL3 EPS is a fructan heterogeneous in molecular weight. SDS PAGE analysis showed that in the LPS from C. salexigens EG1QL3 R-forms prevailed, while in H. ventosae RU5S2EL LPS S-forms were predominant. GLC of acetylated 2-(S)-octylglycosides demonstrated that the LPS of both strains contained D-glucose and L-rhamnose in a different ratio. 3-Hy- droxydodecanoic, hexadecanoic and octadecenoic acids were identified among the main components of the hydrophobic part of the LPS of both strains. The LPS from H. ventosae RU5S2EL is promising for further research on the structure of OPS.
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