Temperature-dependent differences in community structure of bacteria involved in degradation of petroleum hydrocarbons under sulfate-reducing conditions.

AIM The aim of this study was to characterize the microbial community involved in anaerobic degradation of petroleum hydrocarbon under low- and moderate-temperature conditions. METHODS AND RESULTS Sulfate-reducing enrichment cultures growing on crude oil and p-xylene were established at low and moderate temperatures. Bacterial community structures of the cultures were characterized by 16S rRNA gene-based analysis and organisms responsible for degradation of p-xylene were investigated by analysis of the bamA gene, involved in anaerobic degradation of aromatic compounds. The PCR-denaturing gradient gel electrophoresis analysis indicated significant differences in microbial community structures among the cultures, depending on the temperatures of incubation. Difference depending on the temperatures was also observed in the cloning analysis of the bamA gene performed on the p-xylene-degrading enrichment cultures. Majority of clones detected in the culture of moderate temperature were related to Desulfosarcina ovata, whereas more diverse bamA gene sequences were obtained from the culture incubated at low temperature. CONCLUSIONS Temperature-dependent differences in microbial community were demonstrated by the analyses of two genes. It was suggested that sulfate-reducing bacteria of phylogenetically different groups might be involved in the degradation of petroleum hydrocarbons in different temperature environments. SIGNIFICANCE AND IMPACT OF THE STUDY This study is the first report of p-xylene-degrading sulfate-reducing enrichment culture at low temperature. The results of the experiments at low temperature were distinctly different from those reported in previous studies performed at moderate temperatures.