Rapid Degradation of Deepwater Horizon Spilled Oil by Indigenous Microbial Communities in Louisiana Saltmarsh Sediments

Abstract

The Deepwater Horizon oil spill led to the severe contamination of coastal environments in the Gulf of Mexico. A previous study detailed coastal saltmarsh erosion and recovery in a number of oil-impacted and nonimpacted reference sites in Barataria Bay, Louisiana over the first 18 months after the spill. Concentrations of alkanes and polyaromatic hydrocarbons (PAHs) at oil-impacted sites significantly decreased over this time period. Here, a combination of DNA, lipid, and isotopic approaches confirm that microbial biodegradation was contributing to the observed petroleum mass loss. Natural abundance (14)C analysis of microbial phospholipid fatty acids (PLFA) reveals that petroleum-derived carbon was a primary carbon source for microbial communities at impacted sites several months following oil intrusion when the highest concentrations of oil were present. Also at this time, microbial community analysis suggests that community structure of all three domains has shifted with the intrusion of oil. These results suggest that Gulf of Mexico marsh sediments have considerable biodegradation potential and that natural attenuation is playing a role in impacted sites.

Responses of Microbial Communities to Hydrocarbon Exposures

“…Total petroleum hydrocarbons, and aliphatic and aromatic compounds were highly weathered and depleted within the first few months to years after oil from the DWH spill came ashore onto beaches (Hayworth et al, 2015) and wetlands (Mahmoudi et al, 2013;Atlas et al, 2015). Whereas alkanes and low molecular weight PAHs were largely depleted in coastal sediments, high molecular weight PAHs (e.g., chrysene) persisted and could remain for many years.…”

“…Oil contamination from the DWH spill had a profound impact on the abundance, structure, and metabolic potential of sedimentary microbial communities along beaches (Kostka et al, 2011) and marshes (Mahmoudi et al, 2013;Atlas et al, 2015) of the northern Gulf Coast. A time series study conducted at Pensacola Beach, Florida, where total petroleum hydrocarbons reached 11,000 mg kg -1 , revealed a bloom of bacteria during the first four months after oil came ashore, with microbial abundance in oiled sands 10 to 10,000 times that of clean sands (Kostka et al, 2011).…”

“…Hydrocarbons accumulated in marsh sediments were largely degraded within the first few years after oil came ashore (Mahmoudi et al, 2013;Atlas et al, 2015). Oxygen supply dictated the extent of hydrocarbon degradation, and anaerobic microbial populations such as sulfate-reducing members of the Deltaproteobacteria and methanogens increased in relative abundance in sediments where hydrocarbons were degraded .…”

Impact of Photooxidation and Biodegradation on the Fate of Oil Spilled During the Deepwater Horizon Incident: Advanced Stages of Weathering

“…It has been estimated that between 4.2 and 4.9 million barrels of oil were released making it the largest accidental oil spill in history. [1][2][3] Numerous studies have examined the fate and impact of released Macondo oil within the plume [4][5][6][7][8] , on the surface of the Gulf 5,9,10 , buried in ocean sediments (either directly or as marine snow) 6,10 , in marshes [11][12][13][14] , and on beaches. 10,12,14-19 Not surprisingly, the environmental fate of the oil was influenced by many well documented weathering processes.…”

Characteristics of Sediment Bacterial Community in Response to Environmental Impacts in a Sewage Polluted River

“…Accordingly, application of improved indigenous bacterial communities is thought to be a potential bioremediation strategy to overcome pollution problems associated with local river . Mahmoudi et al (2013) reported that spilled oil can be rapidly degraded by the indigenous bacterial community of saltmarsh sediment, suggesting that these of microorganisms have the potential for in situ bioremediation. However, the bacterial communities in river sediment remain largely unexplored owing to complicated environmental stresses and regional bacterial differentiation.…”