Testing the ability of Bacillus spp. isolated from oil contaminated soils for biosurfactant production

      ABSTRACT

   Biosurfactants are surface-active biomolecules that are produced by microorganisms and have a wide variety of potential applications. In the current study, 20 isolates of indigenous Bacillus spp obtained from oil contaminated soils were tested for biosurfactant production by several detection techniques. Specific primers were used to amplify surfactin genes (sfp, srfAA), fengycin genes(fenB, fenD), and iturin genes (ituD, ituC). The results showed that all Bacillus spp. isolates were positive to drop collapse test. The isolate (Sa11) of Bacillus subtilis gave the highest emulsification index ( 63%), while the (Sa19) isolate of Bacillus licheniformis exhibited the highest oil spreading results( 17 mm). 18 of the tested isolates revealed hemolysis ability, while  two isolates belonging to Bacillus circulans and  bacillus firmus were negative to this test. The PCR results showed amplification of srfAA gene in 14 Bacillus isolates, sfp gene in 16 isolates, fenB  gene in 5 isolates, fenD gene in 12 isolates , ituD  gene in 10 isolates, and ituC in 3 isolates. Thus, the isolates of Bacillus spp. used in this study can be used as potential biosurfactant producing bacteria and can also be beneficial for applications regarding bioremediation and industrial processes.