Biphenyl dioxygenases from legacy PCB-contaminated soil
In this study, the diversity of bphA genes was assessed in the 13C-enriched metagenome upon stable isotope probing (SIP) of microbial populations in legacy PCB-contaminated soil with 13C-biphenyl (BP). In total 13 bphA sequence variants (SV) were identified in the final amplicon dataset. Of these, one SV comprised 59% of all sequences. This same BphA sequence also contained unusual amino acids (AAs) Alanin, Valine and Serine in the region III, which was reported to be crucial for substrate specificity of the corresponding biphenyl dioxygenase (BPDO), and was termed according to it BphA_AVS. The DNA locus of 18 kbp containing the BphA_AVS-coding sequence was retrieved from the metagenome and comprised 16 ORFs and was most likely borne by Paraburkholderia sp.