Differential expression of the catabolic nahAc gene and its effect on PAH degradation in Pseudomonas strains isolated from contaminated Patagonian coasts

PAULA ISAAC; HEBE DIONISI; MARIANA LOZADA; CRISTINA ESTÉVEZ; MARCELA FERRERO

INTERNATIONAL BIODETERIORATION & BIODEGRADATION

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2015 vol. 105 p. 1 - 6

0964-8305

A combination of RT-PCR assays and of Northern blots wereused to evaluate the ability of naphthalene,phenanthrene and pyrene to induce nahAcfrom three Pseudomonas isolates obtained from oil contaminated marinesediments. Naphthalene dioxygenase activity based on indigo oxidation correlatedwith nahAc expression in all strains, while variable polycyclic aromatichydrocarbon (PAH) degradation behaviors were observed. Naphthalene wascompletely degraded by all strains; however, whereas high levels of nahAc transcriptswere detected in cultures of Pseudomonas monteilii P26 and Pseudomonas stutzeriN3 grown with naphthalene, significantly lower levels were detected in those ofPseudomonas xanthomarina N12. Phenanthrene was degraded by strain P6 and itstrongly induced nahAc in this strain. On the other hand, although the strainsN12 and N3 removed phenanthrene, the levels of nahAc transcripts were very lowwhen these two strains were grown with this substrate. Remarkably, when P. stutzeriN3 was exposed to pyrene, an intense band of nahAc transcripts was detected byRT-PCR and Northern blot, even though pyrene was degraded to less than 5%. Ourresults indicate that all the strains from coastal Patagonia displayed thepotential to biodegrade PAHs, although in some cases there was no clearcorrelation between nahAc gene expression and the ability to degrade PAHs.na