Preliminary Screening of Biosurfactant Producing Bacteria from Compost and Their Application in Composting Efficiency

In this study biosurfactant producing bacteria which were isolated from compost, were selected during preliminary screening through blood agar hemolysis activity, drop collapse test and oil spreading technique. Isolates with at least more than one positive response to these three methods were subjected to complementary screening by measuring surface tension reduction as well as emulsification capacity. Using these screening methods, two biosurfactant producing isolates have been suc cessfully selected that were able to reduce surface tension effectively. Biochemical analysis determined that these isolates belong to Bacillus and Streptomyces genera. The effect of cell biomass, cell-free supernatant, and a consortium of these two strains on compost quality were determined and specific parameters of compost were analyzed. The results showed that using these bacteria (or supernatants) in compost processing have slight stimulatory effect on bacterial population, surface tension reduction and reduction of pathogens.