Isolation and characterization of crude oil degrading bacillus spp.

Today, application of microorganisms for removing crude oil pollution from contaminated sites as bioremediation studies, was considered by scientists because other methods such as surfactant washing and incineration lead to production of more toxic compounds and they are non-economic. Fifteen crude oil degrading bacillus spp. were isolated from contaminated sites. Two isolated showed best growth in liquid media with 1-3% (v/v) crude oil and mineral salt medium, then studied for enzymatic activities on tested media. The results showed maximal increase in optical densities and total viable count concomitant with decrease in pII on fifth day of experimental period for bacillus S6. Typical generation time on mineral salt with 1% crude oil is varying between 18-20h, 25-26h respectively for bacillus S6 and S35. Total protein was monitored at determined time intervals as biodegradation indices. Increasing of protein concentration during the incubation period reveals that isolated bacillus can degrade crude oil and increase microbial biomass. These bacillus spp. reduced surface tension from 60 (mN/m) to 31 and 38 (mN/m), It means that these bacillus spp. can produce sufficient surfactant and have good potential of emulsification capacity. The results demonstrated that these bacillus spp. can utilize crude oil as a carbon and energy source.