Quantification of phnAc and nahAc in contaminated New Zealand soils by competitive PCR

Unculturable polycyclic aromatic hydrocarbon (PAH)-degrading bacteria are a significant reservoir of the microbial potential to catabolize low-molecul ar-weight PAHs. The population of these bacteria is larger than the populat ion of nah-like bacteria that are the dominant organisms in culture-based s tudies. We used the recently described phn genes of Burkholderia sp. strain RP007, which feature only rarely in culture-based studies, as an alternati ve genotype for naphthalene and phenanthrene degradation and compared this genotype with the genotypically distinct but ubiquitous nah-like class in d ifferent soils. Competitive PCR quantification of phnAc and nahAc, which en code the iron sulfur protein large (alpha) subunits of PAH dioxygenases in nah-like and phn catabolic operons, revealed that the phn genotype can have a greater ecological significance than the nah-like genotype.