ABIOTIC REDUCTION OF 4-CHLORONITROBENZENE TO 4-CHLOROANILINE IN A DISSIMILATORY IRON-REDUCING ENRICHMENT CULTURE

4-chloronitrobenzene (4-Cl-NB) was rapidly reduced to 4-chloroaniline with half-lives of minutes in a dissimilatory Fe(III)-reducing enrichm ent culture. The initial pseudo-first-order rate constants at 25-degre es-C ranged from 0.11 to 0.19 per minute. The linear Arrhenius correla tion in a temperature range of 6 to 85-degree-C and the unchanged reac tivity after pasteurization indicated that the nitroreduction occurred abiotically. A fine-grained black solid which was identified as poorl y crystalline magnetite (Fe3O4) by X-ray diffraction accumulated in th e enrichments. Magnetite produced by the Fe(III)-reducing bacterium Ge obacter metallireducens GS-15 and synthetic magnetite also reduced 4-C l-NB. These results suggest that the reduction of 4-Cl-NB by the enric hment material was a surface-mediated reaction by dissimilatory formed Fe(II) associated with magnetite.