Ercole Claudia, Cacchio Paola, Botta Anna Lucia, Centi Valeria, Lepidi Aldo
Department of Basic and Applied Biology, University of L'Aquila, 67010 L'Aquila, Italy.
Microsc Microanal. 2007 Feb;13(1):42-50. doi: 10.1017/S1431927607070122.
Bacterially induced carbonate mineralization has been proposed as a new method for the restoration of limestones in historic buildings and monuments. We describe here the formation of calcite crystals by extracellular polymeric substances isolated from Bacillus firmus and Bacillus sphaericus. We isolated bacterial outer structures (glycocalix and parietal polymers), such as exopolysaccharides (EPS) and capsular polysaccharides (CPS) and checked for their influence on calcite precipitation. CPS and EPS extracted from both B. firmus and B. sphaericus were able to mediate CaCO3 precipitation in vitro. X-ray microanalysis showed that in all cases the formed crystals were calcite. Scanning electron microscopy showed that the shape of the crystals depended on the fractions utilized. These results suggest the possibility that biochemical composition of CPS or EPS influences the resulting morphology of CaCO3. There were no precipitates in the blank samples. CPS and EPS comprised of proteins and glycoproteins. Positive alcian blue staining also reveals acidic polysaccharides in CPS and EPS fractions. Proteins with molecular masses of 25-40 kDa and 70 kDa in the CPS fraction were highly expressed in the presence of calcium oxalate. This high level of synthesis could be related to the binding of calcium ions and carbonate deposition.
细菌诱导的碳酸盐矿化已被提议作为一种修复历史建筑和古迹中石灰石的新方法。我们在此描述了从坚强芽孢杆菌和球形芽孢杆菌中分离出的细胞外聚合物形成方解石晶体的过程。我们分离了细菌的外部结构（糖萼和壁聚合物），如胞外多糖（EPS）和荚膜多糖（CPS），并检测了它们对方解石沉淀的影响。从坚强芽孢杆菌和球形芽孢杆菌中提取的CPS和EPS能够在体外介导碳酸钙沉淀。X射线微分析表明，在所有情况下形成的晶体都是方解石。扫描电子显微镜显示，晶体的形状取决于所使用的组分。这些结果表明，CPS或EPS的生化组成可能会影响碳酸钙的最终形态。空白样品中没有沉淀。CPS和EPS由蛋白质和糖蛋白组成。阳性阿尔辛蓝染色也显示CPS和EPS组分中存在酸性多糖。在存在草酸钙的情况下，CPS组分中分子量为25 - 40 kDa和70 kDa的蛋白质高度表达。这种高水平的合成可能与钙离子的结合和碳酸盐沉积有关。
