Preferential utilization of petroleum oil hydrocarbon components by microbial consortia reflects degradation pattern in aliphatic-aromatic hydrocarbon binary mixtures

In this study, the abilities of two microbial consortia (Y and F) to degrade aliphatic-aromatic hydrocarbon mixtures were investigated. Y consortium preferentially degraded the aromatic hydrocarbon fractions in kerosene, while F consortium preferentially degraded the aliphatic hydrocarbon fractions. Degradation experiments were performed under aerobic conditions in sealed bottles containing liquid medium and n-octane or n-decane as representative aliphatic hydrocarbons or toluene, ethylbenzene or p-xylene as representative aromatic hydrocarbons (all at 100 mg/l). Results demonstrated that the Y consortium degraded p-xylene more rapidly than n-octane. It degraded toluene, ethylbenzene and p-xylene more rapidly than decane. In comparison, the F consortium degraded n-octane more rapidly than toluene, ethylbenzene or p-xylene, and n-decane more rapidly than toluene, ethylbenzene or p-xylene. 16S rRNA gene sequencing revealed that the Y consortium was dominated by Betaproteobacteria and the F consortium by Gammaproteobacteria, and in particular Pseudomonas. This could account for their metabolic differences. The substrate preferences of the two consortia showed that the aliphatic-aromatic hydrocarbon binary mixtures, especially the n-decane-toluene/ethylbenzene/p-xylene pairs, reflected their degradation ability of complex hydrocarbon compounds such as kerosene. This suggests that aliphatic-aromatic binary systems could be used as a tool to rapidly determine the degradation preferences of a microbial consortium.