Evaluating bacterial community structures in oil collected from the sea surface and sediment in the northern Gulf of Mexico after the Deepwater Horizon oil spill

Abstract

Bacterial community structures were evaluated in oil samples using culture-independent pyrosequencing, including oil mousses collected on sea surface and salt marshes during the Deepwater Horizon oil spill, and oil deposited in sediments adjacent to the wellhead 1 year after the spill. Phylogenetic analysis suggested that Erythrobacter, Rhodovulum, Stappia, and Thalassospira of Alphaproteobacteria were the prevailing groups in the oil mousses, which may relate to high temperatures and strong irradiance in surface Gulf waters. In the mousse collected from the leaves of Spartina alterniflora, Vibrio of Gammaproteobacteria represented 57% of the total operational taxonomic units, suggesting that this indigenous genus is particularly responsive to the oil contamination in salt marshes. The bacterial communities in oil-contaminated sediments were highly diversified. The relatively high abundance of the Methylococcus, Methylobacter, Actinobacteria, Firmicutes, and Chlorofexi bacteria resembles those found in certain cold-seep sediments with gas hydrates. Bacterial communities in the overlying water of the oil-contaminated sediment were dominated by Ralstonia of Betaproteobacteria, which can degrade small aromatics, and Saccharophagus degradans of Gammaproteobacteria, a cellulose degrader, suggesting that overlying water was affected by the oil-contaminated sediments, possibly due to the dissolution of small aromatics and biosurfactants produced during biodegradation. Overall, these results provided key information needed to evaluate oil degradation in the region and develop future bioremediation strategies.

Microbial Community Composition, Functions, and Activities in the Gulf of Mexico 1 Year after the Deepwater Horizon Accident

“…This is consistent with the very sharp redox gradient in deep-sea sediments, with microbial communities in surface sediments being under aerobic conditions and those in deeper sediments under anaerobic conditions. Surficial sediments in our study were codominated by the generally aerobic Alphaproteobacteria and Gammaprotebacteria, consistent with previous reports on the bacterial communities of sediments taken less than 6 km away from the wellhead 1 year after the DWH spill (44). In contrast, directly after the spill, the relative abundance of Deltaproteobacteria anaerobic hydrocarbon degraders and associated functional genes was higher in surficial sediments closest to the blowout site (9).…”

Hydrocarbon-Degrading Bacteria Exhibit a Species-Specific Response to Dispersed Oil while Moderating Ecotoxicity

“…Unlike with prior studies, we investigated how specific bacterial populations interact with crude oil and dispersed oil to elucidate the impacts on bacterial growth, biodegradation potential, and ecotoxicity. Here, we tested two strains based on their relevance to the DWH oil spill and different metabolic strategies (27,49). Alcanivorax is a well-studied obligate hydrocarbonoclastic genus that has a limited carbon substrate range and a cosmopolitan distribution and rapidly responds to oil in the environment (5,28,29).…”

Evaluation of constraints in bioremediation of weathered hydrocarbon-contaminated arid soils through microcosm biopile study

“…The contribution of Alpha-or Gammaproteobacteria varied in the contaminated soils but Actinobacteria, Acidobacteria and Chloroflexi were the other dominant phyla represented. Proteobacteria, Firmicutes, Actinobacteria and Bacteriodetes have been previously identified as hydrocarbon-degrading organisms (Beazley et al 2012;Bell et al 2011;Liu and Liu 2013;Militon et al 2010). Gemmatimonadetes, Bacteroidetes, Nitrospira, Firmicutes, Planctomycetes, Verrumicrobia, TM7, BRC1 and Cynobacteria comprised minor communities in the soil samples analysed.…”

“…Members of the Bacteroidetes, the other phylum present in the soils studied, are also considered to be effective degraders of macromolecules, including cellulose and chitin (Manz et al 1996). Bacterial classification studies by other workers have generally confirmed that Proteobacteria, Actinobacteria and Bacteroidetes are found in soils impacted by hydrocarbons (Beazley et al 2012;Bell et al 2011;Liu and Liu 2013;Røberg et al 2011;Sutton et al 2013).…”

“…The changes in bacterial communities after hydrocarbon contamination in any ecosystem have been described already (Beazley et al 2012;Bell et al 2011;Liu and Liu 2013). Compared to bacteria, little information exists on the dynamics of fungi following hydrocarbon contamination.…”