Microbiological weathering of coarse residue deposit (CRD) kimberlite produced by the Venetia Diamond Mine, Limpopo, South Africa enhanced mineral carbonation relative to untreated material. Cultures of photosynthetically enriched biofilm produced maximal carbonation conditions when mixed with kimberlite and incubated under near surface conditions. Interestingly, mineral carbonation also occurred in the dark, under water-saturated conditions. The examination of mineralized biofilms in ca. 150 µm-thick-sections using light microscopy, X-ray fluorescence microscopy (XFM) and backscatter electron—scanning electron microscopy-energy dispersive x-ray spectrometry demonstrated that microbiological weathering aided in producing secondary calcium/magnesium carbonates on silicate grain boundaries. Calcium/magnesium sulphate(s) precipitated under vadose conditions demonstrating that evaporites formed upon drying. In this system, mineral carbonation was only observed in regions possessing bacteria, preserved within carbonate as cemented microcolonies. 16S rDNA molecular diversity of bacteria in kimberlite and in natural biofilms growing on kimberlite were dominated by Proteobacteria that are active in nitrogen, phosphorus and sulphur cycling. Cyanobacteria based enrichment cultures provided with nitrogen & phosphorus (nutrients) to enhance growth, possessed increased diversity of bacteria, with Proteobacteria re-establishing themselves as the dominant bacterial lineage when incubated under dark, vadose conditions consistent with natural kimberlite. Overall, 16S rDNA analyses revealed that weathered kimberlite hosts a diverse microbiome consistent with soils, metal cycling and hydrocarbon degradation. Enhanced weathering and carbonate-cemented microcolonies demonstrate that microorganisms are key to mineral carbonation of kimberlite.

中文翻译：

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通过接种光合微生物垫加速粗渣金伯利岩材料的矿物生物碳化

相对于未经处理的材料，南非林波波 Venetia 钻石矿生产的粗渣矿床 (CRD) 金伯利岩的微生物风化增强了矿物碳化作用。当与金伯利岩混合并在近地表条件下孵育时，光合富集生物膜的培养物产生最大碳酸化条件。有趣的是，矿物碳酸化也在黑暗中发生，在水饱和的条件下。矿化生物膜的检查。使用光学显微镜、X 射线荧光显微镜 (XFM) 和背散射电子-扫描电子显微镜-能量色散 X 射线光谱仪的 150 µm 厚切片表明，微生物风化有助于在硅酸盐晶界上产生二次碳酸钙/碳酸镁。钙/硫酸镁在渗流条件下沉淀，表明蒸发岩在干燥时形成。在这个系统中，仅在拥有细菌的区域观察到矿物碳化作用，这些细菌以胶结微菌落的形式保存在碳酸盐中。金伯利岩和生长在金伯利岩上的天然生物膜中细菌的 16S rDNA 分子多样性以在氮、磷和硫循环中活跃的变形菌为主。基于蓝藻的富集培养物提供氮和磷（营养素）以促进生长，具有增加的细菌多样性，当在与天然金伯利岩一致的黑暗渗流条件下孵育时，变形杆菌重新确立了自己作为主要细菌谱系的地位。全面的，16S rDNA 分析表明，风化的金伯利岩拥有与土壤、金属循环和碳氢化合物降解一致的多样化微生物组。增强的风化作用和碳酸盐胶结的微菌落表明，微生物是金伯利岩矿物碳化的关键。