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Highlights: [•] Hyperthermophilic, alkalophilic, halophilic bacteria enriched from oil well. [•] Bacterial consortium enhanced oil recovery at 96°C in core flood studies. [•] 96°C is the highest temperature reported for Microbial Enhanced Oil Recovery. [•] Microbial metabolites aiding oil recovery at 96°C were identified. [ABSTRACT FROM AUTHOR]

Enterobacter cloacae strain JD, which produces water-insoluble biopolymers at optimal temperature of 30 °C, and a thermophilic Geobacillus strain were used to construct an engineered strain for exopolysaccharide production at high temperatures by protoplast fusion. The obtained fusant strain ZR3 produced exopolysaccharides at up to 45 °C with optimal growth temperature at 35 °C. The fusant produced exopolysaccharides of approximately 7.5 g/L or more at pH between 7.0 and 9.0. The feasibility of the enhancement of crude oil recovery with the fusant was tested in a sand-packed column at 40 °C. The results demonstrated that bioaugmentation of the fusant was promising approach for MEOR. Mass growth of the fusant was confirmed in fermentor tests. [ABSTRACT FROM AUTHOR]

Abstract: Microbial enhanced oil recovery (MEOR) is a petroleum biotechnology for manipulating function and/or structure of microbial environments existing in oil reservoirs for prolonged exploitation of the largest source of energy. In this study, an Enterobacter cloacae which is capable of producing water-insoluble biopolymers at 37°C and a thermophilic Geobacillus strain were used to construct an engineered strain for exopolysaccharide production at higher temperature. The resultant transformants, GW3-3.0, could produce exopolysaccharide up to 8.83gl−1 in molasses medium at 54°C. This elevated temperature was within the same temperature range as that for many oil reservoirs. The transformants had stable genetic phenotype which was genetically fingerprinted by RAPD analysis. Core flooding experiments were carried out to ensure effective controlled profile for the simulation of oil recovery. The results have demonstrated that this approach has a promising application potential in MEOR. [Copyright &y& Elsevier]

• A novel facultative anaerobic strain Chelatococcus daeguensis HB-4 was first isolated from Oilfield. • The strain HB-4 can degrade long chain hydrocarbons to shorter chains. • Core flooding tests demonstrated 20.5% oil recovery by microbial enhancement, and 59.8% viscosity reduction. • Strain HB-4 can be used for microbial enhanced oil recovery in heavy oil reservoirs. Biodegradation of crude heavy oil was investigated with Chelatococcus daeguensis HB-4 that was isolated from the produced fluid of Baolige Oilfield in China. Batch growth characterization and crude oil degradation tests confirmed HB-4 to be facultative anaerobic and able to degrade heavy oil. The oil degradation was found to occur through degrading long hydrocarbons chains to shorter ones, resulting in oil viscosity reduction. By mixing crude oil with glucose, or using sole crude oil as carbon source, the content of light fractions (C 8 -C 22) increased by 4.97% while heavy fractions (C 23 -C 37) decreased by 7.98%. It was also found that bioemulsifiers were produced rather than commonly observed biosurfactants in the fermentation process, which was attributed to the extracellular degradation of hydrocarbons. Core flooding tests demonstrated 20.5% oil recovery by microbial enhancement, and 59.8% viscosity reduction, showing potential of strain HB-4 for application in the oil industry, especially in enhanced heavy oil recovery. [ABSTRACT FROM AUTHOR]