Response of the Archaeal Community to Simulated Petroleum Hydrocarbon Contamination in Marine and Hypersaline Ecosystems

Petroleum hydrocarbons are among the most important contaminants in aquatic ecosystems, but the effects of different petroleum components on the archaeal communities in these environments are still poorly investigated. Therefore, the effects of representative alkanes, polycyclic aromatic hydrocarbons and crude oil on archaeal communities from marine (Massambaba Beach) and hypersaline waters (Vermelha Lagoon) from the Massambaba Environmental Protection Area, Rio de Janeiro, Brazil, were examined in this study. Hydrocarbon contamination was simulated in vitro, and the resulting microcosms were temporally analyzed (4, 12 and 32 days after contamination) using molecular methods. DNA and RNA extractions were followed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analyses and by the further molecular identification of selected DGGE bands. Archaeal communities could not be detected in the marine microcosms after contamination with the different hydrocarbons. In contrast, they were detected by DNA- and RNA-based methods in hypersaline water. Dendrogram analyses of PCR-DGGE showed that the archaeal communities in the hypersaline water-derived microcosms selected for by the addition of heptadecane, naphthalene or crude oil differed from the natural ones observed before the hydrocarbon contaminations. Principal coordinate analysis of the DGGE patterns showed an important effect of incubation time on the archaeal communities. A total of 103 DGGE bands were identified, and phylogenetic analysis showed that 84.4 % and 15.5 % of these sequences were associated with the Euryarchaeota and Crenarchaeota groups, respectively. Most of the sequences obtained were related to uncultivated archaea. Using redundancy analysis, the response of archaeal communities to the type of hydrocarbon contamination used could also be observed in the hypersaline water-derived microcosms.