Diversity and correlation of specific aromatic hydrocarbon biodegradation capabilities

This work investigated the biodegradation capabilities of indigenous microo rganisms exposed to different combinations of aromatic hydrocarbons. Consid erable diversity was found in the catabolic specificity of 55 strains. Tolu ene 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 biodegrada tion capabilities. Kappa statistics showed a significant correlation betwee n the abilities to degrade toluene and ethylbenzene, p-xylene and m-xylene, and p-xylene and o-xylene. The ability to degrade naphthalene was correlat ed to the ability to degrade other alkylbenzenes, but not benzene. In addit ion, the inability to degrade benzene was correlated to the inability to de grade o-xylene. Factorial analysis of variance showed that biodegradation c apabilities were generally broader when aromatic hydrocarbons were fed as m ixtures than when fed separately. Beneficial substrate interactions include d enhanced degradation of benzene, p-xylene, and naphthalene when toluene w as present, and enhanced degradation of naphthalene by ethylbenzene. Such h euristic relationships may be useful to predict biodegradation patterns whe n bacteria are exposed to different aromatic hydrocarbon mixtures.