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Volume :19 Issue : 1 1992
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Effect of medium salinity on amino acid and phospholipids composition of two halophilic Bacillus species from Saudi Arabia
Auther : ALI A. SALAMAH
Microbiology Unit, Department of Botany, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
ABSTRACT
The cell envelope amino acids of two moderately halophilic Bacillus isolates (BST & BSF) varied according to the salinity of the medium. Cystine and proline were affected mostly. In both isolates growing in the presence of 6 and 18% NaCl there was more dicarboxylic amino acids than basic amino acids which makes the cell envelope proteins acidic. The concentrations of the cell-associated cations (Na+, K+ and Mg2+) were high in both isolates and varied according to the NaCl concentration. The two isolates contained glucosamine and muramic acid in their cell walls. The amounts of these two sugar derivatives, however, varied with the NaCl concentration. Thin-layer chromatography of phospholipids revealed the presence of cardiolipins, phosphatidylglycerols and phosphatidylethanolamines in the two isolates, irrespective of the salinity of the medium. Phosphatidylglycerols and the phosphatidylethanolamines increased with increasing NaCl concentration of the growth medium. Lysophosphatidylglycerols were detected only in the 6%-grown BST cells. Unidentified phospholipids designated X1 (in isolates BSF & BST), X2 (in isolate BST) and X3 (in isolate BSF) were also detected; the concentrations of X1 and X3 were salinity dependent.