| This study provides the first evidence that polycyclic aromatic hydrocarbons (PAHs), particularly naphthalene and phenanthrene, can be degraded under methanogenic conditions, which typically predominate upgradient to the source of contamination. It was also verified that methanogenesis was involved in the degradation pathway using a selective inhibitor of methanogenesis. Further, molecular characterization via 16S rDNA sequences revealed the microbial community structure and suggested the possible roles of the major microbial species in the consortia. Consequently, targeted strategies were developed to isolate and characterize the species from the microbial community to identify their roles in anaerobic PAH biodegradation. In addition to PAHs, anaerobic benzene degradation was investigated because to date, neither successful isolation of benzene-degradees nor characterization of benzene-degrading communities has not been reported under methanogenic conditions. Moreover, surfactants were used to examine the effects of surfactant addition on phenanthrene-degrading microbial communities. The surfactant application inhibited phenanthrene degradation under methanogenic conditions. Further, molecular analysis revealed that the structure of microbial communities was altered and a number of microbial populations including methanogens vanished with surfactant addition. Hence, this result indicates that the disappeared populations and the dormant methanogenic activity might be related to the inhibitory effect on phenanthrene degradation under methanogenic conditions. Finally, this study successfully developed species-specific oligonucleotide probes for the detection of 16S rDNA in environmental samples by using DNA microarrays. The microarray approach identified the presence of target populations in environment samples more efficiently than a traditional molecular monitoring analysis. The results illustrate the potential for using microarray technology to provide a rapid and high-throughput platform for microbial population detection. |
