Adaptation of Pseudomonas aeruginosa to 2,2'-methylenebis (4-chlorophenol).

A culture of Pseudomonas aeruginosa, isolated from a cooling water system, was grown in the presence of sub-inhibitory concentrations of 2,2'-methylenebis(4-chlorophenol) (MBC). It adapted to increasing concentrations from an initial minimum inhibitory concentration of 36 micrograms ml-1 to the highest, 80 micrograms ml-1. Resistant cultures exhibited a higher survival rate when exposed to 320 micrograms ml-1 than did the original strain. Lipopolysaccharide and outer membrane protein profiles were determined by SDS PAGE. No changes were detected in lipopolysaccharide profiles. The quantity of OprP, the phosphate uptake protein in the outer membrane, decreased to a low level correlating with decreased phosphate (P(i)) uptake during growth. It is proposed that OprP is the place of entry for MBC and that the cell can adapt by decreasing the level of OprP in the outer membrane.