BIOSURFACTANTS SYNTHESIS BY PSEUDOMONAS AERUGINOSA BACTERIA ISOLATED FROM THE SURFACE OF MUSSELS OF THE BLACK SEA

Abstract

Aim. Establishing of the ability to synthesize surface-active compounds by Pseudomonas aeruginosa bacteria isolated from the surface of Black Sea mussels. Methods. During the research several marine Pseudomonas spp strains isolated from petroleum hydrocarbon contaminated areas of Black Sea wereused: P. aeruginosa M1, P. aeruginosa M4 and P. aeruginosa PA01 as reference strain in suspension and biofilm cultures (LB and Giss media). Cultivation of Pseudomonas aeruginosa strains was performed at 37 °C for 120 and 168 hours. Planktonic culture growth was determined spectrophotometrically on the wave length 600 nm. Biofilm mass was determined spectrophotometrically on the wave length 592 nm by CV-test. The presence of surface-active compounds was determined in a drop test. The quantitative content of rhamnolipids was evaluated by the color reaction of rhamnose with orcin. Results. P. aeruginosa strains M1 and M4 isolated from Black Sea mussel’s surfaces synthesize 25% and 66% more surfactants than the reference strain PA01. All strains in Giss medium synthesized 10–20 times less rhamnolipids than in LB medium. In biofilm cultures the same biosurfactant synthesis dependence on the composition of the nutrient medium is observed as in suspension cultures. According to the intensity of rhamnolipid production in biofilm cultures, the studied strains can be arranged in the following row: P. aeruginosa M4 > P. aeruginosa M1 >> P. aeruginosa PA01.Conclusions. The strains of P. aeruginosa isolated from the Black Sea are more efficient producers of rhamnolipids than the reference strain of P. aeruginosa PA01; the intensity of biosynthesis of surfactants significantly depends on the composition of the nutrient medium and the method of cultivation.