Microbial Degradation of Alkylbenzenes under Sulfate-Reducing and MethanogenicConditions

摘要

Aquifer solids and soils obtained from various hydrocarbon-contaminated siteswere used to investigate the ability of indigenous microorganisms to degrade monoaromatic hydrocarbons under strictly anaerobic conditions. In anaerobic microcosms inoculated with fuel-contaminated soil from the Patuxent River site, toluene degradation occurred concomitantly with sulfate reduction and ferric iron reduction. Similar results were obtained with suspended enrichments derived from the microcosms. Stoichiometric data and other observations suggested that sulfate reduction was closely linked to toluene degradation, whereas iron reduction was a secondary, potentially abiotic, reaction between ferric iron and biogenic hydrogen sulfide. The presence of millimolar concentrations of amorphous Fe(OH)3 in Patuxent River microcosms and enrichments either greatly facilitated the onset of toluene degradation or accelerated the rate once degradation had begun. Fermentative/methanogenic microcosms and enrichments that degraded toluene and o-xylene without added exogenous electron acceptors (except CO2) were developed from creosote-contaminated Pensacola samples. The microcosms initially underwent an acclimation lag of several months; however, once the degradation of aromatic hydrocarbons was initiated, it proceeded at a relatively rapid rate, and it was complete (resulting in mineralization to CO2 and CH4). Benzene, ethylbenzene, and p-xylene were not degraded.