Biosurfactant production by a chloramphenicol tolerant strain of Pseudomonas aeruginosa

Abstract

A strain of Pseudomonas aeruginosa ATCC 9027, var. RCII, produced biosurfactant in an inorganic phosphate-limited medium supplemented with chloramphenicol (150 μg ml −1). This surfactant reduced the surface tension of the culture supernatant to 29 mN m −1 and its concentration was 50 times the critical micelle concentration (CMC). Several intracellular processes were monitored to correlate biosurfactant production with metabolic changes. In particular, biosurfactant production was preceded by phosphate depletion, followed by increased secretion of alkaline phosphatase (APase) and glutamate, and induction of transhydrogenase (PATH) and glucose-6-phosphate dehydrogenase (G6PD) activity. In the presence of chloramphenicol, a switch from amino acid catabolism to glucose metabolism (reverse diauxie) correlated with the onset of biosurfactant production by P. aeruginosa.