Study On Growth And Metabolism Of Producing Acid Of Microbe For Microbial Enhanced Oil Recovery

Microbes for MEOR as an important component of MEOR could disperse in water/oil/rockinterfacial surface to decrease interfacial tension and change wettability. Its metabolites couldreduce oil viscosity and improve the fluidity of crude oil to improving oil recovery.Growth and metabolism of producing acid of FH-1-2was studied. The research results areas follows：Strain FH-1-2was proved to be Bacillus by physiological and biochemical identification.The change trend of the surface tension, bacteria density, pH value of fermentation broth andcell-surface hydrophobicity of strains FH-1-2was similar under aerobic and facultativeconditions. But strain FH-1-2grew slowly under facultative anaerobic condition. Cell densitycould affect surface tension of fermenting broth. In logarithmic phase of growth, surfacetension of fermentation broth of FH-1-2reduced with the increase of cell density of FH-1-2.But in stationary phase and death phase, the cell density and surface tension of fermentationwere positively correlation. FH-1-2could growth at low concentration of NaCl under30～60℃. The optimum pH for FH-1-2growth was pH6.0～9.0. The cell growth was inhibitedsignificantly when the pH value of fermentation broth was lower than pH6.0.Biosurfactants produced by FH-1-2could reduce the surface tension of the fermentationbroth from68mN·m^-1to42mN·m^-1. Its critical micelle concentration is500mg·L^-1. Thebiosurfactant could keep activity under pH4.0～9.0,30℃～100℃and less then10%concentration of NaCl for two hours respectively. The biosurfactant produced by FH-1-2wasidentified as lipopeptide by thin layer chromatography （TLC） analysis. The fermentationmedium of FH-1-2was optimized by response surface analysis. The lipopeptide yield reached401mg·L^-1, increased66mg·L^-1compared with original medium unoptimized. The organicacid of lipopeptide hydrolyzated was decanoic acid. Gas chromatogram analysis showed thatFH-1-2could produce decanoic acid, tridecylic acid and myristic acid by use of normalheptane, n-octane and n-hexadecane. FH-1-2could produce decanoic acid, tridecylic acid,myristic acid and pentadecanoic acid by use of n-tridecane.