Optimisation of biomineral precipitation in chemoorganotrophic systems for metal recovery

背景生物诱导矿化在微生物中很常见（1）。真菌能够通过不同的机制沉淀矿物质，包括氧化物、碳酸盐、磷酸盐和碳酸盐，但都依赖于化学有机营养代谢以及不同的营养和环境条件（2-4）。在金属矿物地球化学或生物回收的背景下，这些过程很少受到关注。通过控制生长条件，有可能促进金属生物沉淀，这提供了金属的生物回收手段。此外，生物矿物可以是球形、纳米晶体、棒状和管状形式的纳米尺度（1）。鉴于这种制剂的非常高的表面积与体积比和反应性，这提供了进一步的应用兴趣。例如，草酸盐和碳酸盐在许多工业环境中是重要的，包括作为其他有用化合物（例如氧化物）的前体。工业寻求改进的方法，使这些物质的纳米级制剂（5，6）。目前这方面的资料还很缺乏，因此本博士项目提供了一个很好的机会，以获得基础数据，增加对生物矿化在钴和其他金属的地球化学中的理解，以及在生物加工和生产有用的生物矿物产品中的应用意义。（主要是碳酸盐、磷酸盐、碳酸盐），目的是表征和优化每种工艺以获得最大产量。一系列的营养和物理化学变量，如碳和氮源，和pH值，将被调查的不同的生物矿物系统，沿着的机制，在生物矿物沉淀。总体目标是优化所需生物矿物的最大产量，并了解在各种尺度（包括纳米和微米尺度）下实现生物沉淀的条件。将确定从浸出液中的金属混合物中选择性回收Co所需的条件，以及从液体中获得其他沉淀物的可能性，例如Ni的沉淀物。学生将与PDRA一起工作，并将通过接收材料和渗滤液，矿石和渗滤液的化学分析以及与化学无机营养金属浸出和生物沉淀研究结果的比较，与其他研究小组直接互动。学生将接受地质微生物学和地质真菌学，环境地球化学和矿物学的跨学科培训，并将与其他正在进行的研究项目和培训网络，例如Geo-Rep-Net，Geomicrobiology Network，这些项目与环境中的金属流动性有关。参考文献（1）Gadd，G.M.金属、矿物和微生物：地质微生物学和生物修复。Microbiology 156，609 - 643（2010）. (2)Gadd，G.M.地质真菌学：真菌引起的岩石、矿物、金属和放射性核素的地球化学变化，生物风化和生物修复。Mycological Research 111，3-49（2007）. (3)Rhee，Y.J.，Hillier，S. & Gadd，G.M.铅被真菌转化为磷氯铅矿。Current Biology 22，237-241（2012）. (4)魏，Z.，梁湘，Pendlowski，H.，Hillier，S.，Suntornvongsagul，K.，Sihanonth，P. & Gadd，G.M.硅酸锌和硫化矿的真菌生物转化。环境微生物学15，2173-2186（2013）。(5)Aimable，A.，托雷斯普恩特斯，A. & Bowen，P.通过草酸铜路线合成CuO的多孔和纳米结构颗粒。粉末技术208，467-471（2011）。(6)Zhang，S.，（1991），中国农业科学院，王福，He，D. & Jia，R.基于混合模型的草酸钴合成过程粒度分布逐批控制。粉末技术224，253-259（2012）。

BackgroundBiologically-induced mineralization is common in microbes (1). Fungi are capable of precipitating minerals including oxides, carbonates, phosphates and oxalates by differing mechanisms but all dependent on chemoorganotrophic metabolism, and varying nutritional and environmental conditions (2-4). Such processes receive little attention in the contexts of metal biogeochemistry or biorecovery. Through manipulation of growth conditions, it is possible to promote metal bioprecipitation which provides a means of biorecovery of metals. Further, biominerals can be of nanoscale dimensions in spherical, nanocrystalline, rod and tube-like forms (1). This provides further applied interest in view of the very high surface area to volume ratio and reactivity of such preparations. Oxalates and carbonates, for example, are important in many industrial contexts including as precursors of other useful compounds, e.g. oxides. Industry seeks improved means of making nanoscale preparations of such substances (5,6). There is a dearth of information in this area and this PhD project therefore provides an excellent opportunity to obtain fundamental data and increase understanding of biomineralization in the biogeochemistry of Co and other metals, and applied significance in bioprocessing and production of useful biomineral products.WorkplanThis project will investigate the ability of selected geoactive fungal species to biomineralize Co as insoluble biominerals (primarily oxalates, phosphates, carbonates) with the aim being characterisation and optimisation of each process for maximum yield. A range of nutritional and physico-chemical variables, e.g. carbon and nitrogen source, and pH, will be investigated for the different biomineral systems, along with the mechanisms involved in biomineral precipitation. The overall objective is to optimise the maximal yield of desired biominerals, and to understand conditions that enable bioprecipitation at various scales including nano- and microscale. Conditions necessary for selective recovery of Co from metal mixtures in leachates will be determined, as well as the possibility of obtaining other precipitates from liquors, such as those of Ni. The student will work alongside the PDRA, and will directly interact with other research groups through receipt of materials and leachates, chemical analyses of ores and leachates, and comparison of results with chemolithotrophic metal leaching and bioprecipitation studies. The student will receive cross-disciplinary training in geomicrobiology and geomycology, environmental geochemistry and mineralogy, and will interact with other ongoing research projects and training networks, e.g. Geo-Rep-Net, Geomicrobiology Network, that are concerned with metal mobility in the environment.References(1) Gadd, G.M. Metals, minerals and microbes: geomicrobiology and bioremediation. Microbiology 156, 609 - 643 (2010).(2) Gadd, G.M. Geomycology: biogeochemical transformations of rocks, minerals, metals and radionuclides by fungi, bioweathering and bioremediation. Mycological Research 111, 3-49 (2007).(3) Rhee, Y.J., Hillier, S. & Gadd, G.M. Lead transformation to pyromorphite by fungi. Current Biology 22, 237-241 (2012).(4) Wei, Z., Liang, X., Pendlowski, H., Hillier, S., Suntornvongsagul, K., Sihanonth, P. & Gadd, G.M. Fungal biotransformation of zinc silicate and sulfide mineral ores. Environmental Microbiology 15, 2173-2186 (2013). (5) Aimable, A., Torres Puentes, A. & Bowen, P. Synthesis of porous and nanostructured particles of CuO via a copper oxalate route. Powder Technology 208, 467-471 (2011).(6) Zhang, S., Wang, F., He, D. & Jia, R. Batch-to-batch control of particle size distribution in cobalt oxalate synthesis process based on hybrid model. Powder Technology 224, 253-259 (2012).