Anaerobic biodegradation of alicyclic constituents of gasoline and natural gas condensate by bacteria from an anoxic aquifer.

The biodegradation of alicyclic compounds was studied under methanogenic and sulfate-reducing conditions in samples from a gas condensate-contaminated aquifer amended with whole gasoline. Aquifer microorganisms exhibited previously unrecognized anaerobic alicyclic hydrocarbon metabolism of a broad range of substrates at relatively rapid rates. Simple unsubstituted, methyl-substituted, and ethyl-substituted cyclopentenes, cyclopentanes and cyclohexanes were consumed without a substantial lag in the presence of sulfate, but rather less effectively under methanogenic conditions. Dimethyl-substituted cyclopentanes and cyclohexanes were biodegraded only in the presence of sulfate and a limited isomer-specific biodegradative pattern was seen. These results extend the range of hydrocarbons known to be susceptible to anaerobic decay and help indicate the patterns of alicyclic hydrocarbon biodegradation that can be expected.