title: Assessment of the performance of SMFCs in the bioremediation of PAHs in contaminated marine sediments under different redox conditions and analysis of the associated microbial communities.
abstract: The biodegradation of naphthalene, 2-methylnaphthalene and phenanthrene was evaluated in marine sediment microbial fuel cells (SMFCs) under different biodegradation conditions, including sulfate reduction as a major biodegradation pathway, employment of anode as terminal electron acceptor (TEA) under inhibited sulfate reducing bacteria activity, and combined sulfate and anode usage as electron acceptors. A significant removal of naphthalene and 2-methylnaphthalene was observed at early stages of incubation in all treatments and was attributed to their high volatility. In the case of phenanthrene, a significant removal (93.83±1.68%) was measured in the closed circuit SMFCs with the anode acting as the main TEA and under combined anode and sulfate reduction conditions (88.51±1.3%). A much lower removal (40.37±3.24%) was achieved in the open circuit SMFCs operating with sulfate reduction as a major biodegradation pathway. Analysis of the anodic bacterial community using 16S rRNA gene pyrosequencing revealed the enrichment of genera with potential exoelectrogenic capability, namely Geoalkalibacter and Desulfuromonas, on the anode of the closed circuit SMFCs under inhibited SRB activity, while they were not detected on the anode of open circuit SMFCs. These results demonstrate the role of the anode in enhancing PAHs biodegradation in contaminated marine sediments and suggest a higher system efficiency in the absence of competition between microbial redox processes (under SRB inhibition), namely due to the anode enrichment with exoelectrogenic bacteria, which is a more energetically favorable mechanism for PAHs oxidation than sulfate.
authors.affiliation: Department of Civil and Environmental Engineering, Faculty of Engineering and Architecture, American University of Beirut, Beirut, Lebanon.
authors.forename: Hamdan Z
authors.initials: HZ
authors.lastname: Hamdan
authors.affiliation: Department of Civil and Environmental Engineering, Faculty of Engineering and Architecture, American University of Beirut, Beirut, Lebanon. Electronic address: ds40@aub.edu.lb.
authors.forename: Darine A
authors.initials: DA
authors.lastname: Salam
authors.affiliation: Division of Biological and Environmental Sciences and Engineering, Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Ananda Rao
authors.initials: AR
authors.lastname: Hari
authors.affiliation: Department of Environmental Health Sciences, College of Health Sciences, University of Sharjah, Sharjah, UAE.
authors.forename: Lucy
authors.initials: L
authors.lastname: Semerjian
authors.affiliation: Division of Biological and Environmental Sciences and Engineering, Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Pascal
authors.initials: P
authors.lastname: Saikaly
mesh_terms: D001673:Biodegradation, Environmental; D001674:Bioelectric Energy Sources; D019015:Geologic Sediments / Q000737:chemistry*; D010084:Oxidation-Reduction; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D012336:RNA, Ribosomal, 16S; D013431:Sulfates / Q000737:chemistry; D016999:Sulfur-Reducing Bacteria; D014871:Water Microbiology
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D012336:RNA, Ribosomal, 16S; D013431:Sulfates
keywords: Bacterial community; Biodegradation; Polycyclic aromatic hydrocarbons (PAHs); Sediment microbial fuel cell (SMFC); Terminal electron acceptor (TEA)