The importance of bacteria for biodegradation of petroleum is well described for contaminated seawater and coastal soils, but very little is known about the role of symbiotic plant bacteria in degrading petroleum. Endophytes are bacteria and fungi that live as symbionts within plant roots, stems and leaves. These symbionts are closely associated with the plant and some endophyte species serve the dual purpose of promoting plant growth and degrading petroleum inside of plant tissues. In an extreme environment such as a salt marsh, where oxygen is limited in soils, plants may be especially dependent on endophytic bacteria for resilience to stress and to respond to petroleum contamination.
The overall goal of the proposed research is to develop a mechanistic understanding of plant bacterial symbioses in relation to petroleum/dispersant pollution in saline marshes. The proposed work will characterize the transport, fate and catabolic activities of bacterial communities in petroleum-polluted soils and within plant tissues. The project focuses on Spartina alterniflora (smooth cordgrass), the foundational grass species within salt marshes along Atlantic and Gulf coasts. The specific goals are (1) to use next-generation genomic technology for characterizing the taxonomy and function of microbial communities inside of S. alterniflora tissues and in the rhizosphere, while relating these communities to the chemical evolution of crude oil constituents in plant tissues and in soil; and (2) to use new visualization and computational modeling approaches for investigating the biomechanical and chemical influences on bacteria movement at the interface of roots and soil to mechanistically relate bacterial chemotaxis to the presence of petroleum, dispersant, oxygen and root exudates. The proposed research goals directly address GoMRI research theme two, as each ultimately relates plant-symbiont interactions to the chemical evolution and biodegradation of petroleum and dispersants in coastal ecosystems. Pursuing these goals will advance understanding of key processes that occurred in the DWH spill and may occur in future spills.
The outcomes of the proposed research will include (1) a deeper knowledge of the functional genomics of petroleum degradation and uptake of petroleum into plants, (2) the first descriptions and computational models for the biomechanical and chemical aspects of bacterial movement at the root: rhizosphere interface in response to petroleum and dispersant, and (3) the first determination of how plant-endophyte symbioses influence the fate of petroleum in marsh ecosystems. Developing a mechanistic understanding of plant-symbiont-petroleum interactions could provide a foundation for the development of remediation tools using naturally occurring plant-bacteria combinations. Such strategies are being developed in other ecosystems but have not yet been extended to include coastal plants in the Gulf of Mexico (GoM), where there is a persistently high threat of petroleum contamination.
This project was funded by the Gulf of Mexico Research Initiative (GoMRI) in the RFP-V funding program.
The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.