title: Influence of triethyl phosphate on phosphatase activity in shooting range soil: Isolation of a zinc-resistant bacterium with an acid phosphatase.
abstract: Phosphatase-mediated hydrolysis of organic phosphate may be a viable means of stabilizing heavy metals via precipitation as a metal phosphate in bioremediation applications. We investigated the effect of triethyl phosphate (TEP) on soil microbial-phosphatase activity in a heavy-metal contaminated soil. Gaseous TEP has been used at subsurface sites for bioremediation of organic contaminants but not applied in heavy-metal contaminated areas. Little is known about how TEP affects microbial activity in soils and it is postulated that TEP can serve as a phosphate source in nutrient-poor groundwater and soil/sediments. Over a 3-week period, TEP amendment to microcosms containing heavy-metal contaminated soil resulted in increased activity of soil acid-phosphatase and repression of alkaline phosphatase, indicating a stimulatory effect on the microbial population. A soil-free enrichment of microorganisms adapted to heavy-metal and acidic conditions was derived from the TEP-amended soil microcosms using TEP as the sole phosphate source and the selected microbial consortium maintained a high acid-phosphatase activity with repression of alkaline phosphatase. Addition of 5mM zinc to soil-free microcosms had little effect on acid phosphatase but inhibited alkaline phosphatase. One bacterial member from the consortium, identified as Burkholderia cepacia sp., expressed an acid-phosphatase activity uninhibited by high concentrations of zinc and produced a soluble, indigo pigment under phosphate limitation. The pigment was produced in a phosphate-free medium and was not produced in the presence of TEP or phosphate ion, indicative of purple acid-phosphatase types that are pressed by bioavailable phosphate. These results demonstrate that TEP amendment was bioavailable and increased overall phosphatase activity in both soil and soil-free microcosms supporting the possibility of positive outcomes in bioremediation applications.
authors.affiliation: Savannah River National Laboratory, Aiken, SC 29808, USA. Electronic address: sandra.story@furman.edu.
authors.forename: Sandra
authors.initials: S
authors.lastname: Story
authors.affiliation: Savannah River National Laboratory, Aiken, SC 29808, USA. Electronic address: r03.brigmon@srnl.doe.gov.
authors.forename: Robin L
authors.initials: RL
authors.lastname: Brigmon
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D001673:Biodegradation, Environmental; D016956:Burkholderia cepacia / Q000187:drug effects / Q000201:enzymology*; D005389:Firearms; D006023:Glycoproteins / Q000378:metabolism; D060587:Groundwater; D019216:Metals, Heavy / Q000032:analysis; D010755:Organophosphates / Q000494:pharmacology*; D010710:Phosphates / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis; D015032:Zinc / Q000032:analysis
chemical_list: D006023:Glycoproteins; D019216:Metals, Heavy; D010755:Organophosphates; D010710:Phosphates; D012987:Soil; D012989:Soil Pollutants; C091137:purple acid phosphatase; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D010744:Phosphoric Monoester Hydrolases; D015032:Zinc; C009549:triethyl phosphate
keywords: Acid phosphatase; Heavy-metal soil contamination; Triethyl phosphate