NAPHTHALENE AND PHENANTHRENE MINERALIZATION COUPLED TO FE(III) REDUCTION AND MECHANISMS OF ACCESSING INSOLUBLE F_E(III)

摘要

A mixed anaerobic culture from a coal-tar contaminated sediment was found to mineralize naphthalene and phenanthrene when Fe(III) was provided as the major terminal electron acceptor. Naphthalene disappearance of about 100% in 20 days was measured by fluorescence spectrometry in non-radiolabeled experiments. There was a maximum of 53% mineralization detected in radiolabeled naphthalene microcosms in 147 days. Some of the naphthalene that was not mineralized, disappeared due to sorption but the majority of unmineralized naphthalene appeared to have accumulated as metabolic intermediates. The microorganisms at this site appeared to use oxygen, nitrate, Fe(III) and sulphate to degrade naphthalene. Experiments in which ferrihydrite was separated from the microorganisms inside dialysis membranes indicated that direct contact was necessary for extensive Fe(III) reduction, but a compound able to pass through the dialysis membrane also played a role in Fe(III) reduction. The presence of siderophore producers was demonstrated on agar plates containing an Fe(III)-chrome azurol S complex.