Analysis of catabolic genes for naphthalene and phenanthrene degradation in contaminated New Zealand soils

Culture-dependent. and culture-independent methods were used to investigate the diversity of three polycyclic aromatic hydrocarbon (PAH) catabolic gen es in contaminated soils. PAM-degrading bacteria were isolated based on gro wth at the expense of naphthalene (44 isolates) or phenanthrene (35 isolate s). Of these 79 PAH-degraders, 53% (42 isolates) failed to hybridise with t hree gene probes specific for PAH degradation. The gene for the naphthalene dioxygenase iron-sulfur protein (nahAc) from Pseudomonas putida G7 hybridi sed to 45% (20/44) of the culturable naphthalene-degrading bacteria of the 'classical' nah-type, whilst analogues of the bacterial glutathione S-trans ferase (GST) encoding gene of Sphingomonas paucimobilis EPA505 were associa ted with culturable phenanthrene-degrading isolates and hybridised to 29% ( 10/35) of these isolates. Apart from the host strain Burkholderia RP007, we were not able to detect the phnAc gene amongst cultured isolates by hybrid isation or PCR, though could directly amplify this gene from contaminated s oils. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.