The primary goal of this proposal is to determine means of enhancing rates of biodegradation of the hydrocarbons in the coastal zone of the Northern Gulf of Mexico resulting from the catastrophic Deepwater Horizon oil spill. The scope and impact of the this ongoing oil spill disaster are of unprecedented scale and information on key environmental data is critically needed as quickly as possible. The objectives of this research include (1) identify sources of endogenous organic matter in the affected areas that accelerate biodegradation rates, (2) identify the composition and genomic potential of the indigenous microbial consortium to promote polycyclic aromatic hydrocarbons (PAH) degradation and to undergo horizontal gene transfer off PAH genes, and (3) examine changes in rate processes and composition of the microbial consortium as the oil is weathered over the course of a year. The suitability of local marine substrates for enhancing the biodegradation of the hydrocarbons reaching the shore will be determined experimentally. Field experiments with the suitable organic source will be conducted to determine rates of in situ degradation. The composition and genomic potential of the microbial consortium to promote PAH degradation in laboratory and field settings will be investigated. A longer term objective is to develop feasible engineering solutions based on sound biological data to assist in mitigating the long-ranging effects of offshore and coastal oil contamination.
Bruce Hamilton Program Director Environmental Sustainability 5/24/10
The primary goal of this proposal was to determine means of enhancing rates of biodegradation of the hydrocarbons in the coastal zone of the Northern Gulf of Mexico resulting from oil spills. The scope and impact of the Deepwater Horizon accident was of a unprecedented scale and information on accelerating the degradation of hydrocarbons was lacking in coastal sandy sediments in Alabama. Our objective was to determine microbial community responses to exposure to weathered sweet crude oil and conventional diesel in a sandy beach environment. The effects of biostimulation on mineralization of weathered Macondo well crude oil (MC252) in moderately contaminated sand were investigated. Biodegradation was assessed in mesocosm experiments with fuel amounts of 4000 mg kg–1 with the addition of inorganic nutrients (NP) or with either plant based (Spartina alterniflora) or fish based source (Chloroscombrus chrysurus) organic matter. Substantial hydrocarbon mineralization occurred in all treatments, with the highest degradation rates observed in the case of C. chrysurus supplemented sediments. The C. chrysurus addition increased the rates by 123%, while NP addition increased the degradation rates by 52% when compared to oil only treatments. The S. alterniflora addition only increased the degradation rates by 25% during the course of the study. Microbial acclimation periods were observed within 48 hours in all treatments. The bacterial 16S rRNA analyses revealed that most sediment microorganisms belonged to the Proteobacteria (Alpha-, Beta-, Gammaproteobacteria) phylum. A manuscript entitled Biostimulation of weathered Macondo well crude oil in northern Gulf of Mexico sandy sediments was submitted in June 2013 to International Biodeterioration and Biodegradation. The reviews were positive and we revised the manuscript and the mansucript is currently pending with the Editor. The results from our experiments with weathered diesel are currently being analyzed and prepared for publication. Our approach of supplementing organic matter to contaminated sandy sediments has proved to be useful for accelerating the diesel degradation as well. We will submit the resulting manuscript to Journal of Bioremediation and Biodegradation.
