EPA Grant Number: R827015-01-0
Title: Biodegradation of Petroleum Hydrocarbons in Salt-Impacted Soil by Native Halophiles or Halotolerants and Strategies for Enhanced Degradation
Investigators: Babu Z. Fathepure
Institutions: Oklahoma State University
EPA Project Officer: Bala Krishnan
Project Period: January 1, 2002 to June 30, 2002 (N/C Ext. to November 30, 2002)
Project Amount: $20,000
Research Category: Bioremediation of oil spills
ABSTRACT:
The dwindling oil prices of the past has led many major oil-producing
companies in the United States to scale back their operations. As a result the
small firms and individual participants working in the oil patches and gas
fields of the oil-producing states are faced with the difficult challenge of
managing mature fields left behind by the major oil producers. Yet compared
to the major producers, the independent producers are more susceptible to the
unpredictable price of oil and gas and the costs of environmental compliance.
A reduction in environmental compliance costs will have the greatest impact on
the domestic independent producers. Therefore, it is critical that more
cost-effective technologies be developed to treat soil and groundwater that
have been contaminated with high concentrations of salt and oil at exploration
and production (E&P) sites.
Bioremediation processes use bacteria to restore soil and groundwater contaminated with undesirable pollutants. Because of their great metabolic diversity and versatility, microorganisms hold great promise as means to remediating contaminated sites cost-effectively. Bioremediation of oil-brine is particularly challenging since the environment is unforgiving for the survival of externally added bacteria. Therefore, only salt-loving or salt-tolerant microbes are suitable for such hostile environments. Although many halophiles and halotolerants are found in hypersaline environments, little information exists about their ability to degrade petroleum hydrocarbons. Two fundamentally different stategies enable microorganisms to contend with such high osmotic stress. The first mechanism involves the accumulation of high levels of K+ rather than Na+ in the cytoplasm. The second mechanism involves the accumulation of organic compounds called, "osmolytes or compatible solutes". These solutes are accumulated to high intracellular concentrations, in order to balance the osmotic pressure of the surrounding medium and maintain cell turgor for survival. Some of the common intracellular osmoprotectants detected in halophilic/halotolerant bacteria include K+, aspartate, glutamate, proline, glycerol, and glycine betaine.
The primary goal of this work is to demonstrate the biodegradation of simple petroleum hydrocarbons such as benzene and naphthalene under both aerobic and anaerobic conditions (sulfate-reducing) by indigenous populations in oil-brine soils. Also, the study will evaluate strategies for enhancing the growth of halophiles/halotolerants through the addition of known osmoregulant compounds for their ability to degrade petroluem hydrocarbons. Batch microcosms will be prepared with soils obtained from various E&P sites in Oklahoma and other oil-producing states. The microcosms will be amended with radiolabeled benzene or naphthalene and degradation will be monitored by measuring 14CO2. These results are of immense value in cleaning up oil-brine-impacted soil cost effectively.
Principal Investigator: Babu Z. Fathepure
Oklahoma State University
Dept. of Microbiology and Molecular Genetics
Stillwater, OK 74078
Tel: 405-744-7764
Fax: 405-744-6790
E-mail: fathepu@okstate.edu