Selective degradation of biphenyl and methylbiphenyls in crude oil by two strains of marine bacteria

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Abstract
Bacterial isolates were obtained from marine sediment and water enrichment cultures which had been maintained for 3 years by monthly transfers on artificial seawater with Prudhoe Bay crude oil as the sole carbon source. Capillary gas chromatographic analyses showed that two isolates selectively degraded only biphenyl, 3-methylbiphenyl, 4-methylbiphenyl, and three other minor, unidentified compounds in the aromatic fraction. No degradation was detected in the saturate fraction, nor in the sulfur heterocyclic component of the oil. When grown on any of the pure biphenyls, these isolates produced a transient, yellow intermediate which had the spectrophotometric characteristics of α-hydroxymuconic semialdehydes. Growth on either methylbiphenyl compound produced a methylbenzoic acid, indicating that the nonmethylated ring was the first to be cleaved. The isolates, identified as Alcaligenes sp. and Acinetobacter sp., were also able to grow on benzoic acid, 3-, and 4-methylbenzoic acids, indicating that they could further metabolize the aromatic acid intermediates.