RESUMO
The presence of polycyclic aromatic hydrocarbons (PAHs) in marine environments as a result of contamination is an environmental concern, especially in regions where oil spills such as the Deepwater Horizon have occurred. While numerous PAHs have been studied for their effects on microbes, the family of dibenzopyrenes has yet to be investigated. In this preliminary study, the impacts of these molecules on the community structure of a bacterial consortium isolated from oil-impacted Gulf of Mexico sediment were examined using high-throughput sequencing, demonstrating intriguing negative impacts on species diversity and abundance. While no measurable degradation of the dibenzopyrenes was observed after 28-day incubation, the abundance of known oil-degrading bacteria from orders such as Oceanospirillales, Caulobacterales, Sphingomonadales, and Nitrosococcales were shown to be enhanced. Of the five isomers of dibenzopyrene studied, dibenzo[a,h]pyrene supported the fewer number of microbial species suggesting the isomer was more toxic compared to the other isomers.
Assuntos
Bactérias/metabolismo , Benzopirenos/análise , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Benzopirenos/metabolismo , Golfo do México , Poluição por Petróleo/efeitos adversos , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Água do Mar/química , Água do Mar/microbiologia , Poluentes Químicos da Água/metabolismoRESUMO
The rates of crude oil degradation by the extant microorganisms in intertidal sediments from a northern Gulf of Mexico beach were determined. The enhancement in crude oil degradation by amending the microbial communities with marine organic matter was also examined. Replicate mesocosm treatments consisted of: (i) controls (intertidal sand), (ii) sand contaminated with crude oil, (iii) sand plus organic matter, and (iv) sand plus crude oil and organic matter. Carbon dioxide (CO(2)) production was measured daily for 42 days and the carbon isotopic ratio of CO(2) (δ(13)CO(2)) was used to determine the fraction of CO(2) derived from microbial respiration of crude oil. Bacterial 16S rRNA clone library analyses indicated members of Actinobacteria, Bacteroidetes, and Chloroflexi occurred exclusively in control sediments whereas Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Firmicutes occurred in both control and oil contaminated sediments. Members of the hydrocarbon-degrading genera Hydrocarboniphaga, Pseudomonas, and Pseudoxanthomonas were found primarily in oil contaminated treatments. Hydrocarbon mineralization was 76% higher in the crude oil amended with organic matter treatment compared to the rate in the crude oil only treatment indicating that biodegradation of crude oil in the intertidal zone by an extant microbial community is enhanced by input of organic matter.