Ngwenya Bryne T, Magennis Marisa, Podda Francesca, Gromov Andrei
School of GeoSciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, UK
School of GeoSciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW, UK.
J R Soc Interface. 2014 Nov 6;11(100):20140845. doi: 10.1098/rsif.2014.0845.
The induction of mineralization by microbes has been widely demonstrated but whether induced biomineralization leads to distinct morphologies indicative of microbial involvement remains an open question. For calcium carbonate, evidence suggests that microbial induction enhances sphere formation, but the mechanisms involved and the role of microbial surfaces are unknown. Here, we describe hydrozincite biominerals from Sardinia, Italy, which apparently start life as smooth globules on cyanobacterial filaments, and evolve to spheroidal aggregates consisting of nanoplates. Complementary laboratory experiments suggest that organic compounds are critical to produce this morphology, possibly by inducing aggregation of nanoscopic crystals or nucleation within organic globules produced by metabolizing cells. These observations suggest that production of extracellular polymeric substances by microbes may constitute an effective mechanism to enhance formation of porous spheroids that minimize cell entombment while also maintaining metabolite exchange. However, the high porosity arising from aggregation-based crystal growth probably facilitates rapid oxidation of entombed cells, reducing their potential to be fossilized.
微生物诱导矿化已得到广泛证实，但诱导生物矿化是否会导致表明微生物参与的独特形态，仍是一个悬而未决的问题。对于碳酸钙而言，有证据表明微生物诱导会增强球体形成，但其中涉及的机制以及微生物表面的作用尚不清楚。在此，我们描述了来自意大利撒丁岛的水锌矿生物矿物，它们最初显然是以蓝藻丝体上的光滑小球体形式存在，然后演变成由纳米板组成的球状聚集体。补充性的实验室实验表明，有机化合物对于产生这种形态至关重要，可能是通过诱导纳米晶体聚集或在代谢细胞产生的有机小球体内成核来实现。这些观察结果表明，微生物产生细胞外聚合物可能构成一种有效的机制，以增强多孔球体的形成，从而在最小化细胞被包裹的同时维持代谢物交换。然而，基于聚集的晶体生长所产生的高孔隙率可能会促进被包裹细胞的快速氧化，降低它们被石化的可能性。
