Effect of medium salinity on some chemical constituents of two halophilic Bacillus spp. from Saudi Arabia.

Abstract

The cell envelope amino acids of two moderately halophilic Bacillus isolates (BST and BSF) varied according to medium salinity. Cystine and proline were mostly effected. In both isolates growing in the presence of 6 and 18% NaCl there were more dicarboxylic amino acids than basic amino acids which makes the cell envelope proteins quite 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 medium salinity. Phosphatidylglycerols and the phosphatidylethanolamines increased on increasing the NaCl concentration of the growth medium. Lysophosphatidylglycerols were detected only in the 6% grown BST cells. Unidentified phospholipids designated X1 (in isolates BSF and BST), X2 (in isolate BST) and X3 (in isolate BSF) were also detected; the concentrations of X1 and X3 were salinity dependent.