DEVELOPMENT OF MICROORGANISMS WITH IMPROVED TRANSPORT AND BIOSURFACTANT ACTIVITY FOR ENHANCED OIL RECOVERY
Biosurfactants enhance hydrocarbon biodegradation by increasing apparent aqueous solubility or affecting the association of the cell with poorly soluble hydrocarbon. Here, we show that a lipopeptide biosurfactant produced by Bacillus mojavensis strain JF-2 mobilized substantial amounts of residual hydrocarbon from sand-packed columns when a viscosifying agent and a low molecular weight alcohol were present. The amount of residual hydrocarbon mobilized depended on the biosurfactant concentration. One pore volume of cell-free culture fluid with 900 mg/l of the biosurfactant, 10 mM 2,3-butanediol and 1000 mg/l of partially hydrolyzed polyacrylamide polymer mobilized 82% of the residual hydrocarbon. Consistent with the high residual oil recoveries, we found that the bio-surfactant lowered the interfacial tension (IFT) between oil and water by nearly 2 orders of magnitude compared to typical IFT values of 28-29 mN/m. Increasing the salinity increased the IFT with or without 2,3-butanediol present. The lowest interfacial tension observed was 0.1 mN/m. The lipopeptide biosurfactant system may be effective in removing hydrocarbon contamination sources in soils and aquifers and for the recovery of entrapped oil from low production oil reservoirs. Previously, we reported that Proteose peptone was necessary for anaerobic growth and biosurfactant production by B. mojavensis JF-2. The data gathered from crude purification of the growth-enhancing factor in Proteose peptone suggested that it consisted of nucleic acids; however, nucleic acid bases, nucleotides or nucleosides did not replace the requirement for Proteose Peptone. Further studies revealed that salmon sperm DNA, herring sperm DNA, Echerichia coli DNA and synthetic DNA replaced the requirement for Proteose peptone. In addition to DNA, amino acids and nitrate were required for anaerobic growth and vitamins further improved growth. We now have a defined medium that can be used to manipulate growth and biosurfactant production. As an initial step in the search for a better biosurfactant-producing microorganism, 157 bacterial strains were screened for biosurfactant production under both aerobic and anaerobic conditions. A hundred and forty seven strains produced either equal or higher amounts of biosurfactant compared to B. mojavensis JF-2 and the 10 best strains were chosen for further study. In an attempt to increase biosurfactant production, a genetic recombination experiment was conducted by mixing germinating spores of four of the best strains with B. mojavensis JF-2. Biosurfactant production was higher with the mixed spore culture than in the cocultures containing B. mojavensis JF-2 and each of the other 4 strains or in a mixed culture containing all five strains that had not undergone genetic exchange. Four isolates were obtained from the mixed spores culture that gave higher biosurfactant production than any of the original strains. Repetitive sequence-based polymerase chain reaction analysis showed differences in the band pattern for these strains compared to the parent strains, suggesting the occurrence of genetic recombination. We have a large collection of biosurfactant-producing microorganisms and a natural mechanism to improve biosurfactant production in these organisms.
- Research Organization:
- University of Oklahoma (US)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- FC26-02NT15321
- OSTI ID:
- 822122
- Resource Relation:
- Other Information: PBD: 26 Jun 2003
- Country of Publication:
- United States
- Language:
- English
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DEVELOPMENT OF IMPROVED ANAEROBIC GROWTH OF BACILLUS MOJAVENSIS STRAIN JF-2 FOR THE PURPOSE OF IMPROVED ANAEROBIC BIOSURFACTANT PRODUCTION FOR ENHANCED OIL RECOVERY
DEVELOPMENT OF MICROORGANISMS WITH IMPROVED TRANSPORT AND BIOSURFACTANT ACTIVITY FOR ENHANCED OIL RECOVERY