Cs. Lopez et al., VARIATIONS OF THE ENVELOPE COMPOSITION OF BACILLUS-SUBTILIS DURING GROWTH IN HYPEROSMOTIC MEDIUM, Current microbiology, 36(1), 1998, pp. 55-61
The envelope properties of B. subtilis cultures grown in LB and LBN hy
perosmotic media (LB + 1.5 M NaCl) were compared. Since hypertonic cul
tures showed a Spo-phenotype, a Spo-mutant grown in LB was also analyz
ed. LBN cultures showed extensive filamentation and presented differen
t sensitivities toward phage infection (phi 29 and phi 105), or antibi
otics whose targets are at wall (lysozyme, penicillin G) or membrane l
evel (polymyxin B, phosphonomycin). Results of the biochemical composi
tion revealed that during hyperosmotic growth, the cell wall increased
in thickness, and among the membrane lipids, glycolipid and cardiolip
in increased in parallel with a decrease in phosphatidylglycerol. The
fatty acid composition was also modified, and an increase in saturated
straight chain with a decrease of saturated iso-branched fatty acids
was observed. The increase of monounsaturated 18-1 (omega-9) fatty aci
d was probably related to the absence of sporulation observed in hyper
tonic media, since its increase has been shown to inhibit the KinA sen
sor of sporulation. The significance of the other wall and membrane co
mposition variations (and hydrophobic surface properties) in relation
to the osmotic adaptation are discussed.