Research of surface active properties of some microorganisms in various industrial wastes

In this study, totally 26 strains belonging to Pseudomonas aeruginosa and Pseudomonas stutzeri microorganisms were used. While 12 of strains were isolated from the water sample from Çorlu Stream (Tekirdağ Province), 14 were isolated from the petroleum polluted soil in Batman region. The identification of the isolates were carried out using biochemical and physiological tests such as oxidase, denitrification, gelatine hydrolyze, starch hydrolyze, pigmentation and growth (between 5 ? 42 oC) as well as Analytic Profile Index Biochemical Test Kits. In addition, the similarities of all isolates were investigated by protein profiles. Among the identified isolates, P. aeruginosa 78 and P. aeruginosa 99 strains which decreased surface tension of medium 29 and 33 dyne/cm2 respectively and produced highest rhamnolipid (287 and 286 mg/L respectively), P. stuzeri T3 strain which produced highest value (393 mg/mL) of Exopolysaccharide (EPS) were selected in order to use in our studies. Glycerol, Cibri (waste of Rakee Factory) and molasses (waste of sugar factory) were used as a carbon source at rhamnolipid production which is a factor in decreasing surface tension of medium of P. aeruginosa strains. The maximum rhamnolipid production of P. aeruginosa 78 was determined in the molasses medium as 379 mg/L. No bacterial growth in the medium with cibri was observed. It was determined that P. aeruginosa 78 reduced the surface tension of molasses medium to 28 dyne/cm2 and P. aeruginosa 99 to 29 dyne/cm2. Critical micelle concentration of rhamnolipid produced by P. aeruginosa 78 and P. aeruginosa 99 strains was respectively 115 mg/L and 130 mg/L and also the efficiencies at different pH and temperature conditions were determined high. Rhamnolipid producing strains were also produced high yields of EPS. On the other hand P. stuzeri T3 strain which had the highest EPS production did not produce rhamnolipid or a similar surface active agent and EPS produced by P. stuzeri T3 did not have any effect on the medium surface tension. The emulsification activity of rhamnolipid and EPS on benzene, n-hexane, toluene and xylol, and also cell surface hydrophobicities of the strains on these hydrocarbons were investigated. It was dtermined that the rhamnolipids produced by P. aeruginosa 78 and P. aeruginosa 99 had more emulsifier characteristic for benzene (respectively 68 % and 69 %). Emulsification activity of EPS produced by P. aeruginosa 78, 99 and P. stuzeri T3 on hydrocarbons was determined in the range of %66-22. EPS produced by P. aeruginosa 78 had high emulsifier characteristic for toluene (66 %). It was determined that the cell surfaces of P. aeruginosa 78, P. aeruginosa 99 and P. stuzeri T3 strains were more hydrophobe for benzene and toluene hydrocarbons.