title: Phosphatase-mediated bioprecipitation of lead by soil fungi.
abstract: Geoactive soil fungi were examined for their ability to release inorganic phosphate (Pi ) and mediate lead bioprecipitation during growth on organic phosphate substrates. Aspergillus niger and Paecilomyces javanicus grew in 5 mM Pb(NO3)2-containing media amended with glycerol 2-phosphate (G2P) or phytic acid (PyA) as sole P sources, and liberated Pi into the medium. This resulted in almost complete removal of Pb from solution and extensive precipitation of lead-containing minerals around the biomass, confirming the importance of the mycelium as a reactive network for biomineralization. The minerals were identified as pyromorphite (Pb5(PO4)3Cl), only produced by P. javanicus, and lead oxalate (PbC2O4), produced by A. niger and P. javanicus. Geochemical modelling of lead and lead mineral speciation as a function of pH and oxalate closely correlated with experimental conditions and data. Two main lead biomineralization mechanisms were therefore distinguished: pyromorphite formation depending on organic phosphate hydrolysis and lead oxalate formation depending on oxalate excretion. This also indicated species specificity in biomineralization depending on nutrition and physiology. Our findings provide further understanding of lead geomycology and organic phosphates as a biomineralization substrate, and are also relevant to metal immobilization biotechnologies for bioremediation, metal and P biorecovery, and utilization of waste organic phosphates.
authors.affiliation: Geomicrobiology Group, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK.
authors.forename: Xinjin
authors.initials: X
authors.lastname: Liang
authors.affiliation: Electron Microscopy, Central Imaging Facility, Centre for Advanced Scientific Technologies, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Kierans
authors.affiliation: Geomicrobiology Group, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK.|Laboratorio Biodiversità dei Funghi, Dipartimento di Biologia Ambientale, Sapienza Università di Roma, Rome, 00185, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ceci
authors.affiliation: The James Hutton Institute, Aberdeen, AB15 8QH, UK.|Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Stephen
authors.identifier: http://orcid.org/0000-0001-9652-9950
authors.initials: S
authors.lastname: Hillier
authors.affiliation: Geomicrobiology Group, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK.|Laboratory of Environmental Pollution and Bioremediation, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China.
authors.forename: Geoffrey Michael
authors.initials: GM
authors.lastname: Gadd
mesh_terms: D001234:Aspergillus niger / Q000254:growth & development / Q000378:metabolism*; D001669:Biochemical Phenomena; D001673:Biodegradation, Environmental; D005994:Glycerophosphates / Q000378:metabolism; D006999:Hypocreales / Q000254:growth & development / Q000378:metabolism*; D007854:Lead / Q000378:metabolism*; D008903:Minerals / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism*; D010070:Oxalates / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases; D010833:Phytic Acid / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D005994:Glycerophosphates; D008903:Minerals; D009566:Nitrates; D010070:Oxalates; D010710:Phosphates; D012987:Soil; C471364:pyromorphite; D007854:Lead; C017461:lead nitrate; D010833:Phytic Acid; D010744:Phosphoric Monoester Hydrolases