Metagenome, metatranscriptome and single-cell sequencing reveal microbial response to Deepwater Horizon oil spill

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During the Deepwater Horizon oil well blowout in the Gulf of Mexico, the application of 7 million liters of chemical dispersants aimed to stimulate microbial crude oil degradation by increasing the bioavailability of oil compounds. However, the effects of dispersants on oil biodegradation rates are debated. In laboratory experiments, we simulated environmental conditions comparable to the hydrocarbon-rich, 1,100 m deep plume that formed during the Deepwater Horizon discharge. The presence of dispersant significantly altered the microbial community composition through selection for potential dispersant-degrading Colwellia, which also bloomed in situ in Gulf deep waters during the discharge. In contrast, oil addition to deepwater samples in the absence of dispersant stimulated growth of natural hydrocarbon-degrading Marinobacter. In these deepwater microcosm experiments, dispersants did not enhance heterotrophic microbial activity or hydrocarbon oxidation rates. An experiment with surface seawater from an anthropogenically derived oil slick corroborated the deepwater microcosm results as inhibition of hydrocarbon turnover was observed in the presence of dispersants, suggesting that the microcosm findings are broadly applicable across marine habitats. Extrapolating this comprehensive dataset to real world scenarios questions whether dispersants stimulate microbial oil degradation in deep ocean waters and instead highlights that dispersants can exert a negative effect on microbial hydrocarbon degradation rates.

mentioning

confidence: 99%

Chemical dispersants can suppress the activity of natural oil-degrading microorganisms

Kleindienst

Seidel

Ziervogel

et al. 2015

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283

“…Many studies of the plume samples reported that the structure of the microbial communities shifted as time progressed (3)(4)(5)(6)(11)(12)(13)(14)(15)(16)). Member(s) of the order Oceanospirillales dominated from May to mid-June, after which their numbers rapidly declined and species of Cycloclasticus and Colwellia dominated for the next several weeks (4,5,14).…”

mentioning

confidence: 99%

Simulation of Deepwater Horizon oil plume reveals substrate specialization within a complex community of hydrocarbon degraders

Dubinsky

Probst

et al. 2017

108

The Deepwater Horizon (DWH) accident released an estimated 4.1 million barrels of oil and 10 10 mol of natural gas into the Gulf of Mexico, forming deep-sea plumes of dispersed oil droplets and dissolved gases that were largely degraded by bacteria. During the course of this 3-mo disaster a series of different bacterial taxa were enriched in succession within deep plumes, but the metabolic capabilities of the different populations that controlled degradation rates of crude oil components are poorly understood. We experimentally reproduced dispersed plumes of fine oil droplets in Gulf of Mexico seawater and successfully replicated the enrichment and succession of the principal oil-degrading bacteria observed during the DWH event. We recovered near-complete genomes, whose phylogeny matched those of the principal biodegrading taxa observed in the field, including the DWH Oceanospirillales (now identified as a Bermanella species), multiple species of Colwellia, Cycloclasticus, and other members of Gammaproteobacteria, Flavobacteria, and Rhodobacteria. Metabolic pathway analysis, combined with hydrocarbon compositional analysis and species abundance data, revealed substrate specialization that explained the successional pattern of oildegrading bacteria. The fastest-growing bacteria used short-chain alkanes. The analyses also uncovered potential cooperative and competitive relationships, even among close relatives. We conclude that patterns of microbial succession following deep ocean hydrocarbon blowouts are predictable and primarily driven by the availability of liquid petroleum hydrocarbons rather than natural gases.hydrocarbon biodegradation | Gulf of Mexico | microbial communities | Macondo oil | genome succession

“…These intrusion layers were found primarily at a depth of 1,000-1,300 m and may have hosted the majority of the environmental discharge, including all the natural gas and ∼2 million barrels of liquid oil (12). Although the most abundant of the watersoluble hydrocarbons underwent rapid biodegradation during the spill (4,6,8,9,(13)(14)(15), the fate and impacts of the insoluble hydrocarbons in the deep ocean have remained uncertain (16).…”

mentioning

confidence: 99%

Fallout plume of submerged oil from Deepwater Horizon

Valentine

Fisher

Bagby

et al. 2014

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Significance Following the sinking of the Deepwater Horizon in the Gulf of Mexico an unprecedented quantity of oil irrupted into the ocean at a depth of 1.5 km. The novelty of this event makes the oil’s subsequent fate in the deep ocean difficult to predict. This work identifies a fallout plume of hydrocarbons from the Macondo Well contaminating the ocean floor over an area of 3,200 km 2 . Our analysis suggests the oil initially was suspended in deep waters and then settled to the underlying sea floor. The spatial distribution of contamination implicates accelerated settling as an important fate for suspended oil, supports a patchwork mosaic model of oil deposition, and frames ongoing attempts to determine the event’s impact on deep-ocean ecology.