Effect of subsurface electrical heating and steam injection on the indigenous microbial community

摘要

Since the potential for contaminant bioremediation in steam treated subsurface environments has not been explored, the thermal remedial treatment of a gasoline spill at Lawrence Livermore National Laboratory's (LLNL) Livermore site provided an opportunity to study microbial community changes in the subsurface environment. We studied changes in community structure and population abundance as well as the characteristics of indigenous heat-tolerant microorganisms before and after steam treatment. Using fatty acid profiles from culturable microorganisms obtained from sediment cores before and after thermal treatment, a 90-98% decline in total microorganism populations in hot subsurface sediments (up to 94 deg C) was found. Surviving heat-tolerant microorganisms were found to possess elevated concentrations of saturated fatty acids in their lipid membranes. We also observed that some heat-tolerant microorganisms were capable of degrading gasoline compounds.