Research on the biogenic-specific polymorphism and morphology of carbonate has been gaining momentum in the fields of biomineralization and industrial engineering in recent years. We report the nucleation of carbonate particles on bacterial cell templates to produce a novel dumbbell-like morphology which was assembled by needle-like crystals of magnesium calcite or aragonite radiating out from both ends of the template bacterium. Mature dumbbell-like structures had a tendency to break apart in the central template region, which was made up mostly of weak amorphous carbonate. Further crystal growth, especially at the template region, transformed the broken pieces into spherulites. Rod-like cell templates were essential for the formation of dumbbell-like morphologies, and we propose a possible formation mechanism of the dumbbell-like morphology. Our findings provide new perspectives on the morphological formation mechanism in biomineralization systems and may have a potential significance in assembling composite materials suitable for industrial applications.

中文翻译：

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具有哑铃状形态的碳酸盐矿物在细菌细胞模板上的可控结晶和转化

近年来，碳酸盐的生物成因特异性多态性和形态研究在生物矿化和工业工程领域获得了蓬勃发展。我们报道了碳酸盐颗粒在细菌细胞模板上的成核以产生一种新的哑铃状形态，该形态由从模板细菌两端辐射出的镁方解石或文石的针状晶体组装而成。成熟的哑铃状结构在中心模板区域有破裂的趋势，该区域主要由弱无定形碳酸盐组成。进一步的晶体生长，特别是在模板区域，将碎片转化为球晶。棒状细胞模板对于哑铃状形态的形成是必不可少的，我们提出了一种可能的哑铃状形态形成机制。