A dibenzofuran (DF)-degrading bacterium, Nocardioides sp. DF412, was isolated and its genes responsible for the degradation of DF were cloned and characterized. The dfdA1A2A3A4 gene cluster coding for a ring hydroxylating dioxygenase was located on a plasmid, and the dfdBC gene cluster coding for a ring-cleavage dioxygenase and a following hydrolase respectively was located on the chromosome. Reverse transcription-PCR analysis revealed that the transcription of both gene clusters was induced in the presence of DF. These two gene clusters also conferred the activity of each enzyme to a host strain. These results strongly suggest that the clusters are responsible for the degradation of DF in strain DF412.