Microbial Enhancement of Oil Recovery.

The microbial enhanced oil recovery (MEOR) uses specialised microorganisms along with the injection of certain nutrients such as sugars, phosphates, and nitrates into the oil well to produce metabolic activities thus, forming products such as bio-surfactants, polymers, acids and gases which, lead to an increase in oil recovery. Economically, MEOR is more attractive in comparison with other oil recovery processes because it requires less capital and operating costs. The present project is based on selecting particular microorganisms, which can produce biosurfactants and other useful products to enhance the oil recovery, by inevitably increasing the reservoir pressure, reducing interfacial tension of the oil, increasing the oil flow to the production well and plugging the high permeable zones. In this study, 42 strains were isolated from the mixture of the contaminated soil obtained from a car garage (Woking, Surrey) and from an oil reservoir obtained from the Iranian Oil field (based in Ahvaz). They were isolated using complex and minimal media with added crude oil or hexadecane. These strains were then studied for their biomass concentrations and metabolic activities. The initial screen was based on their bio-surfactant production, as revealed by the formation of a zone of clearance on Blood agar plates and results were compared with those of Pseudomonas putida which was obtained from a culture collection company based in UK. Strains which were unable to produce bio-surfactant were removed from the next round of screening and therefore, the results were narrowed to selected number of strains. The production of other chemicals, such as acids, polymers, and gases were also studied to various levels. On the basis of this investigation, 5 strains were chosen for further characterisation. These strains were initially identified by using staining techniques and other biochemical techniques and finally they were identified using 16SrDNA sequence analysis. These isolated strains were found to be closely related to Bacillus licheniformis, and Bacillus cereus. These strains grew on a variety of substrates and, at temperatures of 37°C and 55°C. However, one of the strains was not identified in this study and this strain was found growing at a temperature of 65°C