Microbial community responses to organophosphate substrate additions in contaminated subsurface sediments

• Published in: PloS one Vol. 9; no. 6; p. e100383
• Main Authors: Martinez, Robert J, Wu, Cindy H, Beazley, Melanie J, Andersen, Gary L, Conrad, Mark E, Hazen, Terry C, Taillefert, Martial, Sobecky, Patricia A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 20.06.2014; Public Library of Science (PLoS)
• Subjects: Amendments; Archaea; Archaea - cytology; Archaea - metabolism; Bacteria; Bacteria - cytology; Bacteria - metabolism; Biodegradation, Environmental; Biology and Life Sciences; Cold War; Communities; Community; Contaminants; Contaminated sediments; Contamination; Deoxyribonucleic acid; DNA; Earth science; Earth Sciences; Electric power plants; Energy policy; ENVIRONMENTAL SCIENCES; Experiments; Federal agencies; Fieldwork; Geologic Sediments - chemistry; Glycerol; Glycerol-3-phosphate; Government agencies; Groundwater; Groundwater pollution; Heavy metals; Hydrogen ions; Hydrolysis; Laboratories; Metabolism; Microbial activity; Microbiomes; Microorganisms; Mineralization; Minerals; Nuclear electric power generation; Nuclear energy; Nuclear power; Nuclear power plants; Nuclear war; Nuclear weapons; Organophosphates - chemistry; Organophosphates - metabolism; pH effects; Phosphatase; Phosphate; Phosphates; Physical Sciences; Precipitation; Radioisotopes; Relative abundance; Ribosomal DNA; rRNA 16S; Science & Technology - Other Topics; Sediment pollution; Sediments; Slurries; Solubility; Substrates; Taxa; Uranium; Uranium - chemistry; Uranium - metabolism; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0100383

Radionuclide- and heavy metal-contaminated subsurface sediments remain a legacy of Cold War nuclear weapons research and recent nuclear power plant failures. Within such contaminated sediments, remediation activities are necessary to mitigate groundwater contamination. A promising approach makes use of extant microbial communities capable of hydrolyzing organophosphate substrates to promote mineralization of soluble contaminants within deep subsurface environments. Uranium-contaminated sediments from the U.S. Department of Energy Oak Ridge Field Research Center (ORFRC) Area 2 site were used in slurry experiments to identify microbial communities involved in hydrolysis of 10 mM organophosphate amendments [i.e., glycerol-2-phosphate (G2P) or glycerol-3-phosphate (G3P)] in synthetic groundwater at pH 5.5 and pH 6.8. Following 36 day (G2P) and 20 day (G3P) amended treatments, maximum phosphate (PO4(3-)) concentrations of 4.8 mM and 8.9 mM were measured, respectively. Use of the PhyloChip 16S rRNA microarray identified 2,120 archaeal and bacterial taxa representing 46 phyla, 66 classes, 110 orders, and 186 families among all treatments. Measures of archaeal and bacterial richness were lowest under G2P (pH 5.5) treatments and greatest with G3P (pH 6.8) treatments. Members of the phyla Crenarchaeota, Euryarchaeota, Bacteroidetes, and Proteobacteria demonstrated the greatest enrichment in response to organophosphate amendments and the OTUs that increased in relative abundance by 2-fold or greater accounted for 9%-50% and 3%-17% of total detected Archaea and Bacteria, respectively. This work provided a characterization of the distinct ORFRC subsurface microbial communities that contributed to increased concentrations of extracellular phosphate via hydrolysis of organophosphate substrate amendments. Within subsurface environments that are not ideal for reductive precipitation of uranium, strategies that harness microbial phosphate metabolism to promote uranium phosphate precipitation could offer an alternative approach for in situ sequestration.