Identification and Application of Biosurfactants for Use in Marine Oil Spill Remediation

Oil releases can produce significant environmental consequences, and in the marine environment chemical dispersants are often an integral part of early response measures, applied to break up oil slicks, enhance microbial hydrocarbon (HC) degradation and minimise (visible) pollution of coastal environments. However, there is growing concern about the longevity and potential adverse effects of the dispersants in the marine environment. In case of the Deepwater Horizon (DWH) disaster in the Gulf of Mexico in 2010, almost 800 000 t of the dispersant Corexit were added to the well and while this is thought to have kept much of the oil from forming a surface slick, the dispersant itself was found to persist much longer in the environment than expected and in itself trigger significant negative ecological consequences.
Biosurfactants are surface-active amphipathic molecules with wide structural diversity, which endows them with their unique properties, including better environmental compatibility, higher selectivity and biodegradability in comparison to synthetic surfactants. Biosurfactants produced by marine bacteria in particular retain their activity at extreme temperatures, pH and salinity due to the metabolic and physiological adaptations of marine microorganisms to survive in extreme habitat1. As marine biosurfactants facilitate the process of emulsification of hydrocarbons in the aqueous phase, thereby enhancing the availability for microbial uptake and degradation, they have outstanding potential application in the field of oil spill bioremediation. Nevertheless, very few marine microbial communities have been explored for production of surface active molecules. With oil exploration and extraction fast progressing into deep water, an urgent need arises to understand biodegradation processes in this deep water environment and to optimize response measures after a potential oil spill using bioremediation approaches. The applicants’ ongoing investigations on hydrocarbon degradation in deep sediments from the FSC have shown strong bioremediation capability of HC pollution by indigenous microbial communities and production of biosurfactants/bioemulsifiers in mixed microbial cultures. Clone library analysis identified the presence of the genuses Alcanivorax, Pseudomonas, Halomonas, Colwellia and members of the family Rhodobacteraceae in the enriched cultures, all of which are known to include biosurfactant/bioemulsifier producing strains2. A collection of isolated potential hydrocarbon degrading bacteria (HDB) strains from the FSC is also available for further study.
This PhD project will test existing and new isolates for biosurfactant/bioemulsifier production, HC solubilisation and utilisation of HCs as sole C source. The potential of selected isolates for bioaugmentation will be investigated by co-inoculation with an HC-degrading consortium from the study area. Opportunities for further sampling in the FSC are available and the student will have the opportunity to explore the efficacy of different isolation techniques to maximise the number of isolated microorganisms. The biosurfacants produced will be isolated and fully characterised in terms of both their chemical structures and efficacy of operation with a longer term objective of producing synthetic analogues. Production of biosurfactants/bioemulsifiers and their impact on HC degradation will be examined in cultures of deep-sea HDB communities and/or isolates amended with crude oil or selected HCs. HDBs will be identified via molecular microbiology techniques. The student will be trained in a range of marine sediment biogeochemical analyses (organic and inorganic), analytical chemistry techniques such as GC-FID, HPLC, FTIR and NMR as well as traditional culturable and molecular microbiology techniques for phylogenetic identification of isolates and organisms in mixed cultures. The student will benefit from wider interaction, training opportunities and access to facilities across the Doctoral Training Programmes at the Universities of Aberdeen and St Andrews, and the JHI (Abdn).