Ferrier John, Csetenyi Laszlo, Gadd Geoffrey Michael
Geomicrobiology Group, School of Life Sciences, University of Dundee, Dundee, Scotland, DD1 5EH, UK.
School of Science and Engineering, Fulton Building, University of Dundee, Dundee, Scotland, DD1 5HN, UK.
Environ Microbiol. 2022 Feb;24(2):667-677. doi: 10.1111/1462-2920.15526. Epub 2021 May 6.
Manganese oxide minerals can become enriched in a variety of metals through adsorption and redox processes, and this forms the basis for a close geochemical relationship between Mn oxide phases and Co. Since oxalate-producing fungi can effect geochemical transformation of Mn oxides, an understanding of the fate of Co during such processes could provide new insights on the geochemical behaviour of Co. In this work, the transformation of Mn oxides by Aspergillus niger was investigated using a Co-bearing manganiferous laterite, and a synthetic Co-doped birnessite. A. niger could transform laterite in both fragmented and powder forms, resulting in formation of biomineral crusts that were composed of Mn oxalates hosting Co, Ni and, in transformed laterite fragments, Mg. Total transformation of Co-doped birnessite resulted in precipitation of Co-bearing Mn oxalate. Fungal transformation of the Mn oxide phases included Mn(III,IV) reduction by oxalate, and may also have involved reduction of Co(III) to Co(II). These findings demonstrate that oxalate-producing fungi can influence Co speciation in Mn oxides, with implications for other hosted metals including Al and Fe. This work also provides further understanding of the roles of fungi as geoactive agents which can inform potential applications in metal bioremediation, recycling and biorecovery.
氧化锰矿物可通过吸附和氧化还原过程富集多种金属，这构成了锰氧化物相和钴之间密切地球化学关系的基础。由于产草酸盐的真菌可影响锰氧化物的地球化学转化，了解钴在此类过程中的归宿可为钴的地球化学行为提供新见解。在这项工作中，利用含钴的锰质红土和合成的钴掺杂水钠锰矿研究了黑曲霉对锰氧化物的转化。黑曲霉可转化破碎和粉末形式的红土，形成由含有钴、镍以及在转化的红土碎片中含有镁的草酸锰组成的生物矿壳。钴掺杂水钠锰矿的完全转化导致含钴草酸锰沉淀。锰氧化物相的真菌转化包括草酸盐对锰（III,IV）的还原，也可能涉及钴（III）还原为钴（II）。这些发现表明，产草酸盐的真菌可影响锰氧化物中钴的形态，对包括铝和铁在内的其他宿主金属也有影响。这项工作还进一步理解了真菌作为地球活性因子的作用，可为金属生物修复、回收和生物提取的潜在应用提供参考。
