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In this study, 26 Pseudomonas spp. were isolated from a stream polluted by factory waste and from petroleum-contaminated soil. The surface tension (ST) of the cultures was used as a criterion for the primary isolation of biosurfactant-producing bacteria. | Turkish Journal of Biology Turk J Biol (2014) 38: 307-317 © TÜBİTAK doi:10.3906/biy-1303-18 http://journals.tubitak.gov.tr/biology/ Research Article Production of biosurfactant by Pseudomonas spp. isolated from industrial waste in Turkey 1 1 2 1, Tayfun KAYA , Belma ASLIM , Ergin KARİPTAŞ * Department of Biology, Faculty of Arts and Science, Ahi Evran University, Kırşehir, Turkey 2 Department of Biology, Faculty of Science, Gazi University, Ankara, Turkey Received: 20.03.2013 Accepted: 23.08.2013 Published Online: 14.04.2014 Printed: 12.05.2014 Abstract: In this study, 26 Pseudomonas spp. were isolated from a stream polluted by factory waste and from petroleum-contaminated soil. The surface tension (ST) of the cultures was used as a criterion for the primary isolation of biosurfactant-producing bacteria. Biosurfactant production was quantified by ST reduction, critical micelle concentration (CMC), emulsification capacity (EC), and cell surface hydrophobicity (CSH). Two of the isolates, P. aeruginosa 78 and 99, produced rhamnolipid biosurfactant. The strains started rhamnolipid production in the logarithmic phase. They decreased the ST of the culture from 73 dyne/cm2 to 29 and 33 dyne/cm2, and the CMC of produced rhamnolipids were 115 and 130 mg/L, respectively. P. aeruginosa 78 and 99 strains emulsified benzene and n-hexane at the highest rates, and the surfaces of these strains were 73% and 65% and 62% and 72% more hydrophobic for benzene and toluene, respectively. Key words: Rhamnolipid, Pseudomonas spp., surface tension, critical micelle concentration, emulsification activity, cell surface hydrophobicity 1. Introduction Surface active agents are substances that can reduce the surface and interface tension in liquids and liquid systems (i.e. oil/water, air/water, or liquid/solid) and can be produced through synthetic (surfactant) or microbial (biosurfactant) methods (Christofi and Ivshina, 2002; Khalladi et al., 2009). These substances have the .
