Diversity and correlation of specific aromatic hydrocarbon biodegradation capabilities

Abstract

This work investigated the biodegradation capabilitiesof indigenous microorganisms exposed to differentcombinations of aromatic hydrocarbons. Considerablediversity was found in the catabolic specificity of 55strains. Toluene was the most commonly degradedcompound, followed by p-xylene, m-xyleneand ethylbenzene. Strains capable of degradingo-xylene and benzene, which were theleast-frequently-degraded compounds, exhibited broaderbiodegradation capabilities. Kappa statistics showeda significant correlation between the abilities todegrade toluene and ethylbenzene, p-xylene andm-xylene, and p-xylene and o-xylene. The ability to degrade naphthalene was correlated tothe ability to degrade other alkylbenzenes, but notbenzene. In addition, the inability to degradebenzene was correlated to the inability to degradeo-xylene. Factorial analysis of variance showedthat biodegradation capabilities were generallybroader when aromatic hydrocarbons were fed asmixtures than when fed separately. Beneficialsubstrate interactions included enhanced degradationof benzene, p-xylene, and naphthalene whentoluene was present, and enhanced degradation ofnaphthalene by ethylbenzene. Such heuristicrelationships may be useful to predict biodegradationpatterns when bacteria are exposed to differentaromatic hydrocarbon mixtures.