lux-Marked Pseudomonas aeruginosa lipopolysaccharide production in the presence of rhamnolipid

Rhamnolipid produced by Pseudomonas aeruginosa during the late logarithmic growth phase has been reported to be an effective biosurfactant. In the presence of rhamnolipid, P aeruginosa had a higher specific lipopolysaccharide production, which was attributed to the increase of carbon to nitrogen ratios owing to the increase of the solubility of hydrophobic hydrocarbons, favoring the synthesis of lipopolysaccharides. P. aeruginosa also had a higher ratio of lipopolysaccharides in the growth medium to those on cell surfaces than in the absence of rhamnolipid because the presence of rhamnolipid stimulated the release of lipopolysaccharides from P. aeruginosa cell outer membranes. The release of lipopolysaccharides from cell surfaces made P. aeruginosa exhibit a more hydrophobic surface, enhancing the accumulation of hydrophobic hydrocarbons on P. aeruginosa cell surfaces and consequently resulting in a higher growth rate. (C) 2004 Elsevier B.V. All rights reserved.