Indigenous production of biosurfactant and degradation of crude oil

Abstract

The present study investigated the isolation and identification of biosurfactant producing bacteria from Iranian oil wells. The biosurfactant production of bacteria isolates was evaluated and confirmed using hemolysis and emulsification tests. The biodegradation of crude oil was studied using GC and HPLC analysis. A total of 45 strains have been isolated. These strains showed less than a 40 mN m-1 reduction in surface tension. The effects of different pH (4.2-9.2), salinity concentrations (1%-15%), and temperatures (25-50) in biosurfactant production of isolated strains were evaluated. One of the strains (Bacillus sp. NO.4) showed a high salt tolerance and a successful production of biosurfactant in a vast pH range. Its maximum biomass production (about 3.1 g L-1 dry weight) was achieved after 60 hours of growth. The surface tension of the culture broth dropped rapidly after inoculation and reached its lowest value (36 mN m-1) during the exponential phase after about 36-48 hours of growth. The study of the GC graphs showed that higher aliphatic reduction occurred in fractions with C14 to C24 hydrocarbons. The depicted results of the HPLC graphs indicated a 100% degradation of chrysene and fluorine. In this study, we demonstrated the useful capacities of the isolates in removing oil pollutants and their application in MEOR in vitro.

Keywords

• indigenous
• biosurfactant
• bacteria
• crude oil