Isolation and Screening of Hydrocarbon Utilizing Bacteria for Biosurfactant Production: Application for Enhanced Oil Recovery

Abstract

Tertiary oil recovery techniques comprise miscible flooding, chemical, thermal and microbial injection into oil reservoirs to enhanced recovery. Several studies have been performed on the use of surfactants and polymers injection for enhanced oil recovery. But this study is focused on isolation and characterization of hydrocarbon utilizing bacteria for biosurfactants and biopolymers production. The concept of microbial enhanced oil recovery consists the injection of nutrients to activate indigenous microbes in the reservoir or injection of external hydrocarbon degrading microbes plus nutrients during field applications to ensure the organisms produce the required metabolites. These microbes have the ability to produce gases to increase reservoir pressure and displacement of immobile oil, bio-surfactants to reduce interfacial tension, biopolymer for mobility control, Injectivity profile and viscosity modification, solvent, acid and biomass. In this study, soil samples were obtained from hydrocarbon-contaminated site in Gio, Tai Local Government Area, in Ogoniland, Rivers State, Nigeria. The samples were transferred into a polythene bag, placed in an ice pack, and transported immediately to the laboratory for physicochemical and microbiological analyses such as emulsification index, haemolytic activity and oil spreading technique. 37 isolates were tested for biosurfactant production and 3 of the isolates were selected for biosurfactant production with strong ability to degrade hydrocarbon. The selected microbes (Bacillus sp, Pseudomonas sp and Enterobacter sp) were identified by biochemical characterization and subjected to ranges of temperature, pH, nutrient sources, salinity, and inoculum concentration to determine their optimum reservoir performance conditions. The result shows the optimum parameter ranges for the three microbes: pH 7-8, temperature within 25 – 35°C, salinity within 0.5% - 5%, the result shows that as the inoculum size increases, the more the emulsification index, the best nitrogen source is peptone and the best carbon source for bacillus sp is glucose and glycerol for Pseudomonas sp and Enterobacter sp.