Microbially induced calcium carbonate precipitation (MICP) has recently become an intelligent and environmentally friendly method for the repair of cracks in concrete. In order to improve the ability of microbial materials to repair concrete cracks, we applied random mutagenesis and optimization of mineralization conditions to improve the quantity and crystal form of microbially precipitated calcium carbonate. Sporosarcina pasteurii ATCC 11859 was used as the starting strain to obtain the mutant with high urease activity by atmospheric and room temperature plasma (ARTP) mutagenesis. Then, the optimal biomineralization conditions and precipitation crystal form was studied using Plackett-Burman experimental design and response surface methodology (RSM). Biomineralization with 0.73 mol/L calcium chloride, 45 g/L urea, reaction temperature of 45°C, and reaction time of 22 h, significantly increased the amount of precipitated calcium carbonate, which was deposited in the form of calcite crystals. Finally, the repair of concrete using the optimized biomineralization process was evaluated. A comparison of water absorption and adhesion of concrete specimens before and after repairs showed that concrete cracks and surface defects could be efficiently repaired. This study provides a new method for the engineering of biocementing material for concrete repair.

中文翻译：

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通过大气和室温等离子体诱变和响应面方法改进巴斯德氏孢子八叠球菌作为混凝土修复的生物胶结材料的生物矿化。

微生物诱导碳酸钙沉淀 (MICP) 最近已成为一种智能且环保的混凝土裂缝修复方法。为了提高微生物材料修复混凝土裂缝的能力，我们采用随机诱变和优化矿化条件来提高微生物沉淀碳酸钙的数量和晶型。巴氏孢子八叠球菌以ATCC 11859为起始菌株，通过常压室温等离子(ARTP)诱变获得高脲酶活性突变体。然后，使用 Plackett-Burman 实验设计和响应面方法 (RSM) 研究了最佳生物矿化条件和沉淀晶型。用 0.73 mol/L 氯化钙、45 g/L 尿素、反应温度 45°C 和反应时间 22 h 进行生物矿化，显着增加了以方解石晶体形式沉积的沉淀碳酸钙的量。最后，对使用优化的生物矿化工艺修复混凝土进行了评估。修复前后混凝土试件的吸水率和附着力对比表明，混凝土裂缝和表面缺陷可以得到有效修复。