Biostimulation of weathered MC252 crude oil in northern Gulf of Mexico sandy sediments

The effects of biostimulation on mineralization of weathered Macondo (MC252) crude oil in moderately contaminated sand were investigated. Biodegradation was assessed in microcosm experiments containing 4000 mg kg−1 weathered Macondo oil and either amended with inorganic nutrients (NP), or organic matter in the form of either plant (Spartina alterniflora) or fish-amendments (Chloroscombrus chrysurus). Hydrocarbon mineralization occurred in all treatments, with the highest degradation rates observed in C. chrysurus supplemented sediments. The C. chrysurus addition increased the rates by 123%, while NP addition increased the degradation rates by 52% compared to oil only treatments. In contrast, the S. alterniflora addition increased the degradation rates by 25% during the course of the study. Microbial acclimation periods were observed within 48 h in all treatments. Bacterial analyses revealed the presence of Proteobacteria (Alpha-, Beta-, Gammaproteobacteria) phylum with members that were closely related to known hydrocarbon degraders.