Degradation of phospholipid in Pseudomonas aeruginosa induced by polymyxin B

Effects of polymyxin B on the synthesis and degradation of lipid, ribonucleic acid (RNA) and protein in Pseudomonas aeruginosa were investigated. It was found that polymyxin B caused a marked degradation of the lipid fraction which was prelabeled with (3H-2)-glycerol. Thin-layer chromatographic analysis indicated that the main degraded lipids were phosphatidylethanolamine and phosphatidylglycerol, which constituted 80% and 15% of the total phospholipids of this organism, respectively. Polymyxin B also inhibited synthesis of RNA and protein in vivo. The severe inhibition of the uptake of labeled amino acids by polymyxin B indicated that the observed inhibition of RNA and protein synthesis possibly occurred at the level of substrate transports. The degradation of phospholipid might account for the defective membrane activities.