Investigation of the presence of biosurfactant producing microorganisms in extreme soils

In this study, biosurfactant production was carried out by Bacillus velezensis, Bacillus haynesii, Bacillus halotolerans, Pseudomonas reinekei, Microbacterium arborescens, Pseudomonas veronii and Acinetobacter lwoffii using olive oil as a carbon source. Optimization of pH, temperature and carbon source for biosurfactant production was carried out. Antimicrobial effects of B.velezensis, P.reinekei and M.arborescens bacteria (50 and 100 microliters) on some pathogens (Staphylococcus aureus ATCC 29213, Escherichia coli, Salmonella spp., Klebsiella spp. and Candida albicans) were determined by using disc diffusion method. According to the results obtained, the highest biosurfactant production of the isolates (B.velezensis, P.veronii P.reinekei) was found according to the oil spread technique after 15 days of incubation, but the highest biosurfactant production in 72 hours of incubation was in B.halotolerans and B. haynesii. In the emulsification index measurement of the biosurfactants produced by the isolates, xylene and sunflower oil hydrocarbons reduce the surface tension by forming emulsion layers, but in the analysis with n-heptane, there is little or no emulsion layers. all biosurfactants produced by the isolates (at 50 µL and 100 µL concentrations) have inhibitory activity against the pathogens used. As a result, maximum biosurfactant production was achieved by adding 5% olive oil as a carbon source, the medium was adjusted to pH 8 and were incubated at 37ºC. It has been determined that the produced biosurfactants reduce the surface tension and have antibacterial and antifungal effects against many pathogens.