title: The role of root exuded low molecular weight organic anions in facilitating petroleum hydrocarbon degradation: current knowledge and future directions.
abstract: Rhizoremediation is a bioremediation technique whereby enhanced microbial degradation of organic contaminants occurs within the plant root zone (rhizosphere). It is considered an effective and affordable 'green technology' for remediating soils contaminated with petroleum hydrocarbons (PHCs). This paper critically reviews the potential role of root exuded compounds in rhizoremediation, with emphasis on commonly exuded low molecular weight aliphatic organic acid anions (carboxylates). The extent to which remediation is achieved shows wide disparity among plant species. Therefore, plant selection is crucial for the advancement and widespread adoption of this technology. Root exudation is speculated to be one of the predominant factors leading to microbial changes in the rhizosphere and thus the potential driver behind enhanced petroleum biodegradation. Carboxylates can form a significant component of the root exudate mixture and are hypothesised to enhance petroleum biodegradation by: i) providing an easily degradable energy source; ii) increasing phosphorus supply; and/or iii) enhancing the contaminant bioavailability. These differing hypotheses, which are not mutually exclusive, require further investigation to progress our understanding of plant-microbe interactions with the aim to improve plant species selection and the efficacy of rhizoremediation.
authors: School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors: Belinda C
authors: BC
authors: Martin
authors: School of Earth and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors: Suman J
authors: SJ
authors: George
authors: School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors: Charles A
authors: CA
authors: Price
authors: School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors: Megan H
authors: MH
authors: Ryan
authors: School of Earth and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; Department of Environmental Science and Technology, Cranfield University, College Road, Bedfordshire, MK43 0AL England, United Kingdom. Electronic address: Mark.Tibbett@cranfield.ac.uk.
authors: Mark
authors: M
authors: Tibbett
mesh_terms: D000838:Anions / Q000378:metabolism; D001673:Biodegradation, Environmental; D006838:Hydrocarbons / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D008970:Molecular Weight; D010578:Petroleum / Q000032:analysis / Q000378:metabolism*; D053147:Plant Exudates / Q000737:chemistry*; D018517:Plant Roots / Q000502:physiology*; D058441:Rhizosphere; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000838:Anions; D006838:Hydrocarbons; D010578:Petroleum; D053147:Plant Exudates; D012989:Soil Pollutants
keywords: Biodegradation; Organic acids; Petroleum hydrocarbons; Phytoremediation; Rhizosphere; Root exudates