石油および環境バイオテクノロジージャーナル

概要

Laboratory Investigation of Thermoanaerobacter brockii Subsp. Lactiethylicus Strain 9801T for Possible Utilization in Microbial Enhanced Oil Recovery

Erik G. Søgaard

Thermoanaerobacter brockiisubsp. lactiethylicus strain 9801T originally isolated from a deep reservoir environment was evaluated for potential use in microbial enhanced oil recovery (MEOR). Investigation was conducted for finding the optimum environmental parameters for growth (temperature, salinity and pH) and production of metabolites desired for microbial enhanced oil recovery. There was growth in the media with pH from 6-9.5 and salinity range of 0.5-3.5% (w/v) and temperature of 50-60oC. The optimum growth occurred at about pH of 7 and temperature of 55oC. The fermentable substrates included molasses, reinforced clostridia medium, thioglycolate and crude oil with major fermentation end products being lactic acid, volatile fatty acids and some amount of gas that included carbon dioxide. The concentration of lactic acid reached 11.7 g/l with a corrosive effect on core chalk samples that led to dissolution and release of calcium ions approximately 38 times greater than the background value. Additionally, this strain also produced biomass with a yield of between 0.0034-0.052 g/h per 100 ml of broth. Result of biosurfactant production assay indicated an oil displacement area of 3.5 cm2 and fermentation of crude oil indicated a significant reduction in concentration of long chain alkanes in both light and heavy oils. Finally this strain compared favorably well in terms of metabolites production with other known bacteria strains employed in MEOR thus confirming the potential of Thermoanerobacter brockii subsp lactiethylicus 9801T for utilization in microbial enhance oil recovery.