By combining the results of 16S T-RFLP and SNuPE fingerprinting, significant correlations were found between the community compositions and the expression of some subfamily I.2.C C23O genes. Consequently, a still uncultured member of the genus Rhodoferax and an unclassified Rhodocyclaceae bacterium were identified as possible microaerobic BTEX degraders, as well as Pseudomonas strains that harbored the TOL plasmid containing two non-homologous C23O genes. However, further studies will include microcosm experiments and culturing approaches to verify these findings.