The paper was delivered by internationally recognized microbiologist Dr. Ronald Atlas of the University of Louisville at the American Chemical Society conference in San Francisco in August 2014.
Three sites in Barataria Bay, LA, including two coastal salt marsh locations impacted by the release of Macondo oil (MC-252) and one unimpacted reference site, were studied between 2011 and 2013. Samples collected from these sites were analyzed to determine the concentration of oil components as well as the structure of the microbial community. Researchers measured concentrations of saturated hydrocarbons, polycyclic aromatic hydrocarbons and petroleum biomarkers to 1) determine if the hydrocarbons were associated with MC-252 oil, and 2) to calculate the extent of oil degradation. The project team also extracted DNA from the samples and used whole metagenome sequencing to determine the relative abundances of different species of microbes, including those known to degrade oil.
No MC252 oil was detected in the surface sediment at the reference site, and the microbial community was very diverse. At a heavily oil-impacted aerobic site (containing oxygen in the sediment), the concentrations of petroleum hydrocarbons, which were attributed to MC-252 oil, declined significantly from 2011 to 2013. These samples showed relatively large proportions of the aerobic hydrocarbon-degrading bacterium Marinobacter hydrocarbonoclasticus. By comparison, at a heavily oil-impacted site which was anaerobic (containing very little oxygen), the concentrations of petroleum hydrocarbons, which were also attributed to MC-252 oil, did not decline as drastically between 2011 and 2013. At this site, a single bacterial species,Desulfococcus oleovorans, accounted for more than half of the overall microbial community in 2011. In both cases, enrichment of oil-associated microbial populations declined between 2011 and 2013, and microbial diversity returned to the high levels similar to those observed at the unimpacted site reference marsh.
Battelle is a leading provider of advanced biological and hydrocarbon analyses to the oil and gas sector. Our research laboratories employ biomarker and other high-resolution capabilities to support advanced hydrocarbon analysis, finger printing and source attribution, and ecological risk assessment. Our microbial genomics team uses molecular biology metagenomics, metaproteomics, and metatranscriptomics to identify microrganisms involved in hydrocarbon biodegradation and associated metabolic pathways.