Ceci Andrea, Kierans Martin, Hillier Stephen, Persiani Anna Maria, Gadd Geoffrey Michael
Geomicrobiology Group, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom Laboratorio Biodiversità dei Funghi, Dipartimento di Biologia Ambientale, Sapienza Università di Roma, Rome, Italy.
Electron Microscopy, Central Imaging Facility, Centre for Advanced Scientific Technologies, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom.
Appl Environ Microbiol. 2015 Aug;81(15):4955-64. doi: 10.1128/AEM.00726-15. Epub 2015 May 15.
Fungi play important roles in biogeochemical processes such as organic matter decomposition, bioweathering of minerals and rocks, and metal transformations and therefore influence elemental cycles for essential and potentially toxic elements, e.g., P, S, Pb, and As. Arsenic is a potentially toxic metalloid for most organisms and naturally occurs in trace quantities in soil, rocks, water, air, and living organisms. Among more than 300 arsenic minerals occurring in nature, mimetite [Pb5(AsO4)3Cl] is the most stable lead arsenate and holds considerable promise in metal stabilization for in situ and ex situ sequestration and remediation through precipitation, as do other insoluble lead apatites, such as pyromorphite [Pb5(PO4)3Cl] and vanadinite [Pb5(VO4)3Cl]. Despite the insolubility of mimetite, the organic acid-producing soil fungus Aspergillus niger was able to solubilize mimetite with simultaneous precipitation of lead oxalate as a new mycogenic biomineral. Since fungal biotransformation of both pyromorphite and vanadinite has been previously documented, a new biogeochemical model for the biogenic transformation of lead apatites (mimetite, pyromorphite, and vanadinite) by fungi is hypothesized in this study by application of geochemical modeling together with experimental data. The models closely agreed with experimental data and provided accurate simulation of As and Pb complexation and biomineral formation dependent on, e.g., pH, cation-anion composition, and concentration. A general pattern for fungal biotransformation of lead apatite minerals is proposed, proving new understanding of ecological implications of the biogeochemical cycling of component elements as well as industrial applications in metal stabilization, bioremediation, and biorecovery.
真菌在生物地球化学过程中发挥着重要作用，如有机物分解、矿物和岩石的生物风化以及金属转化，因此影响着必需元素和潜在有毒元素（如磷、硫、铅和砷）的元素循环。砷对大多数生物来说是一种潜在有毒的类金属，天然存在于土壤、岩石、水、空气和生物体内，含量极少。在自然界中存在的300多种砷矿物中，砷铅矿[Pb5(AsO4)3Cl]是最稳定的砷酸铅，与其他不溶性铅磷灰石（如磷氯铅矿[Pb5(PO4)3Cl]和钒铅矿[Pb5(VO4)3Cl]）一样，在通过沉淀进行原位和异位封存及修复的金属稳定化方面具有很大潜力。尽管砷铅矿不溶，但产有机酸的土壤真菌黑曲霉能够溶解砷铅矿，同时沉淀出草酸铅作为一种新的真菌源生物矿物。由于之前已有关于磷氯铅矿和钒铅矿的真菌生物转化的记录，本研究通过应用地球化学模型并结合实验数据，推测出一种真菌对铅磷灰石（砷铅矿、磷氯铅矿和钒铅矿）进行生物转化的新生物地球化学模型。这些模型与实验数据高度吻合，能够准确模拟砷和铅的络合以及生物矿物形成，这取决于例如pH值、阳离子 - 阴离子组成和浓度等因素。本文提出了铅磷灰石矿物真菌生物转化的一般模式，为组成元素生物地球化学循环的生态意义以及金属稳定化、生物修复和生物回收等工业应用提供了新的认识。
