Toxicological and Environmental Chemistry, 1985, Vol. 10, pp. 225-246 0277-2248/85/1003-0225 $18.50/0 © 1985 Gordon and Breach, Science Publishers, Inc. and OPA Ltd. Printed in Great Britain Gas Chromatographie-Mass Spectrometric Characterization of Bacterial Metabolites of 4-Nitrobiphenyl Formed in Gram Negative Strain B-206 † ROBERT MASSÉ, MOHAMED BADR and CHRISTIANE AYOTTE Institut National de la Recherche Scientifique (INRS-Santé), Université du Québec, 7401, rue Hochelaga, Montréal, Québec, Canada H1N 3M5 and MICHEL SYLVESTRE Centre de Recherche en Bactériologie, Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada H7N 4Z3 (Received 23 November, 1984) The metabolism of 4-nitrobiphenyl have been studied in pure cultures of a facultative gram negative strain. The bacterium was able to grow using 4-nitrobiphenyl as the sole carbon source. The biotransformation products were isolated and identified by combined gas chromatography-mass spectrometry. Intermediate metabolites of the bio- transformation cascade were identified as 2,3-dihydro-2,3-dihydroxy-4'-nitrobiphenyl, 3,4-dihydro-3,4-dihydroxy-4'-nitrobiphenyl,3,4-dihydroxy-4'-nitrobiphenyl,2-hydroxy-6- oxo-6-(4'-nitrophenyl) hexanoic acid and 4-nitrocinnamic acid. In addition 2 and 4-hydroxy-4'-nitrobiphenyls were detected in the neutral extracts whereas minute amounts of 2-hydroxy-3-nitroso-4'-nitrobiphenyl and 4-amino benzoic acid were also detected. The results from this study indicate that 4-nitrobiphenyl was degraded to the corresponding nitro-benzoic acid. The data reported here also suggests that there is a minor metabolic route in the microbial cultures leading to hydroxylated compounds which is similar to those reported in mammalian systems. In addition, †Presented at the 14th Annual Symposium on the Analytical Chemistry of Pollutants, Barcelona, November 21-23, 1984. 225