The bacterial community structure of hydrocarbon-polluted marine environments as the basis for the definition of an ecological index of hydrocarbon exposure

LOZADA, M.; MARCOS, M.S.; COMMENDATORE, M.G.; GIL, M.N.; DIONISI, H.M.

MICROBES AND ENVIRONMENTS

JAPANESE SOC MICROBIAL ECOLOGY

Año: 2014 vol. 29 p. 269 - 276

1342-6311

The aim of this study was to design a molecular biological tool using information provided by amplicon pyrosequencing of 16S rRNA genes that was suitable for use in marine ecosystems for environmental assessments and bioremediation. We selected 63 bacterial genera that were previously linked to hydrocarbon biodegradation to represent a minimum sample of the bacterial guild associated with this process. We defined an ecological indicator (ecological index of hydrocarbon exposure, EIHE) using the relative abundance values of these genera obtained by pyrotag analysis. This index reflected the proportion of the bacterial community that was potentially capable of biodegrading hydrocarbons. When the bacterial community structures of intertidal sediments from two sites with different pollution histories were analyzed, 16 of the selected genera (25%) were significantly overrepresented with respect to the pristine site, in at least one of the samples from the polluted site. Although the relative abundances of individual genera associated with hydrocarbon biodegradation were generally low in samples from the polluted site, EIHE values were 4 times higher than those in the pristine sample, with at least 5% of the bacterial community in the sediments being represented by the selected genera. EIHE values were also calculated in other oil-exposed marine sediments as well as in seawater using public datasets from experimental systems and field studies. In all cases, the EIHE was significantly higher in oiled than in unpolluted samples, suggesting that this tool could be used as an estimator of the hydrocarbon-degrading potential of microbial communities.