Abundance of Polycyclic Aromatic Hydrocarbon-degrading Populations in Patagonian Coastal Sediments

MARCOS, M.S.; LOZADA, M.; GIL, M.N.; COMMENDATORE, M.G.; DI MARZIO, W.D.; DIONISI, H.M

Puerto Madryn

Congreso; XLVI Reunion Anual de la Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular; 2010

The aim of this project was to quantify polycyclic aromatic hydrocarbon (PAH)- degrading bacterial populations in coastal sediments of Northern Patagonia. We analyzed the relative abundance of various genes encoding PAH dioxygenases by qPCR, in DNA extracted from intertidal sediment samples collected at Fracasso Beach, a protected area, and Cordova Cove, a chronically polluted site. We quantified the following catabolic genes: phnA1 (Cycloclasticus spp.), nahAc (Pseudomonas spp.), phnAc (Alpha-Proteobacteria) and C, a novel dioxygenase gene previously detected in Subantarctic sediments. Additionally, we quantified 16S rRNA genes using a universal primer set. Physico-chemical parameters, including ORP, granulometry, organic matter, ammonium and hydrocarbon concentrations, were also measured in these samples. phnA1 genes were abundant in polluted sediments, and their abundance was found to be two orders of magnitude higher in sediments with twice the concentration of 3-ring PAHs. The other analyzed genes were found to be present, although below quantification limit for this technique. These results suggest that Cycloclasticus, a marine obligate hydrocarbonoclastic bacterium, plays an important role in the biodegradation of low molecular weight PAHs in coastal sediments of Patagonia. Laboratory scale studies are being performed to analyze population dynamics after crude oil or PAH exposure.