title: Profiling bacterial communities associated with sediment-based aquaculture bioremediation systems under contrasting redox regimes.
abstract: Deposit-feeding invertebrates are proposed bioremediators in microbial-driven sediment-based aquaculture effluent treatment systems. We elucidate the role of the sediment reduction-oxidation (redox) regime in structuring benthic bacterial communities, having direct implications for bioremediation potential and deposit-feeder nutrition. The sea cucumber Holothuria scabra was cultured on sediments under contrasting redox regimes; fully oxygenated (oxic) and redox stratified (oxic-anoxic). Taxonomically, metabolically and functionally distinct bacterial communities developed between the redox treatments with the oxic treatment supporting the greater diversity; redox regime and dissolved oxygen levels were the main environmental drivers. Oxic sediments were colonised by nitrifying bacteria with the potential to remediate nitrogenous wastes. Percolation of oxygenated water prevented the proliferation of anaerobic sulphate-reducing bacteria, which were prevalent in the oxic-anoxic sediments. At the predictive functional level, bacteria within the oxic treatment were enriched with genes associated with xenobiotics metabolism. Oxic sediments showed the greater bioremediation potential; however, the oxic-anoxic sediments supported a greater sea cucumber biomass. Overall, the results indicate that bacterial communities present in fully oxic sediments may enhance the metabolic capacity and bioremediation potential of deposit-feeder microbial systems. This study highlights the benefits of incorporating deposit-feeding invertebrates into effluent treatment systems, particularly when the sediment is oxygenated.
authors.affiliation: School of Marine Science and Technology, Newcastle University, Newcastle, NE1 7RU, UK.|Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown 6140, South Africa.
authors.forename: Georgina
authors.initials: G
authors.lastname: Robinson
authors.affiliation: School of Marine Science and Technology, Newcastle University, Newcastle, NE1 7RU, UK.
authors.forename: Gary S
authors.initials: GS
authors.lastname: Caldwell
authors.affiliation: School of Civil Engineering and Geosciences, Newcastle University, Newcastle, NE1 7RU, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Wade
authors.affiliation: Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FF, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Free
authors.affiliation: Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown 6140, South Africa.
authors.forename: Clifford L W
authors.initials: CLW
authors.lastname: Jones
authors.affiliation: School of Marine Science and Technology, Newcastle University, Newcastle, NE1 7RU, UK.
authors.forename: Selina M
authors.initials: SM
authors.lastname: Stead
mesh_terms: D000818:Animals; D017756:Aquaculture / Q000379:methods*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D001673:Biodegradation, Environmental; D044822:Biodiversity; D018533:Biomass; D005798:Genes, Bacterial; D019015:Geologic Sediments / Q000382:microbiology*; D047332:Holothuria / Q000254:growth & development*; D056186:Metagenomics; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis; D021521:Ribotyping; D013696:Temperature
chemical_list: D010100:Oxygen