Diversity and correlation of specific aromatic hydrocarbon biodegradation capabilities

This work investigated the biodegradation capabilities of indigenous microorganisms exposed to different combinations of aromatic hydrocarbons. Considerable diversity was found in the catabolic specificity of 55 strains. Toluene was the most commonly degraded compound, followed by p-xylene, m-xylene and ethylbenzene. Strains capable of degrading o-xylene and benzene, which were the least-frequently-degraded compounds, exhibited broader biodegradation capabilities. Kappa statistics showed a significant correlation between the abilities to degrade toluene and ethylbenzene, p-xylene and m-xylene, and p-xylene and o-xylene. The ability to degrade naphthalene was correlated to the ability to degrade other alkylbenzenes, but not benzene. In addition, the inability to degrade benzene was correlated to the inability to degrade o-xylene. Factorial analysis of variance showed that biodegradation capabilities were generally broader when aromatic hydrocarbons were fed as mixtures than when fed separately. Beneficial substrate interactions included enhanced degradation of benzene, p-xylene, and naphthalene when toluene was present, and enhanced degradation of naphthalene by ethylbenzene. Such heuristic relationships may be useful to predict biodegradation patterns when bacteria are exposed to different aromatic hydrocarbon mixtures.