Microbially enhanced oil recovery at simulated reservoir conditions by use of engineered bacteria

A polymer-producing strain of Enterobacter sakazakii, designated JD, can excrete highly viscous water-insoluble polysaccharide at temperatures lower than 30 °C. Another strain, Bacillus subtilis I, can survive in harsh environments. These two strains were genetically recombined by protoplast fusion, and two excellent fusants designated STP-1 and STP-5 were obtained. The performances of biogas and extracellular polysaccharide production, as well as enhanced oil recovery, were evaluated by sand-pack flooding tests. STP-1 exhibited lower ability to produce biogas but higher capability of biopolymer production and enhanced oil recovery than STP-5. The decreasing percentage of the core permeability after microbe flooding was 83% by STP-1 and 58% by STP-5, respectively. STP-1 enhanced oil recovery by 25%, and STP-5 17%, from the saturated sand pack column. To the authorsʹ knowledge, this is the first report about the construction of engineering bacteria which have the advantages of both high temperature resistance and high polysaccharide production.