Complementing urea hydrolysis and nitrate reduction for improved microbially induced calcium carbonate precipitation
Complementing urea hydrolysis and nitrate reduction for improved microbially induced calcium carbonate precipitation
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DOI：
10.1007/s00253-019-10128-2
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发表时间：
2019-10
影响因子：
5
通讯作者：
Xuejiao Zhu;Jianyun Wang;N. De Belie;N. Boon
中科院分区：
文献类型：
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作者：
Xuejiao Zhu;Jianyun Wang;N. De Belie;N. Boon
微生物诱导碳酸钙沉淀已广泛应用于细菌基自愈混凝土中。然而，将细菌引入不相容的混凝土基质后，其生物生成碳酸钙的能力有限，这是这项技术的主要挑战。在本研究中，研究了在一株细菌中同时结合尿素水解和硝酸盐还原这两条代谢途径来提高细菌碳酸钙产量的可能性。从3株候选菌株中筛选出一株耐钙性最强的菌株Ralstonia eutrohaH16，该菌株在复合培养基中既能进行尿素水解又能进行硝酸盐还原。结果表明，H16的尿素水解不需要氧气，尿素酶活性主要由细胞浓度决定。然而，在复合培养基中添加尿素会使硝酸盐还原速率减慢至7天，直到NO3-−完全分解。此外，H16的硝酸盐还原明显受到介质中钙离子浓度的增加的限制。然而，通过两条代谢途径的结合，优化后的碳酸钙总沉淀率可以提高20%~30%。通过正交试验得到的碳酸钙沉淀率最高可达14 g/L，说明该菌是一株能同时激活尿素水解和硝酸盐还原的细菌，可用于提高碳酸钙沉淀率，对细菌基自愈混凝土中多种代谢途径的激活作用可在以后进一步研究。
Microbial-induced CaCO3precipitation has been widely applied in bacterial-based self-healing concrete. However, the limited biogenetic CaCO3production by bacteria after they were introduced into the incompatible concrete matrix is a major challenge of this technology. In the present study, the potential of combining two metabolic pathways, urea hydrolysis and nitrate reduction, simultaneously in one bacteria strain for improving the bacterial CaCO3yield has been investigated. One bacterial strain,Ralstonia eutrophaH16, which has the highest Ca2+tolerance and is capable of performing both urea hydrolysis and nitrate reduction in combined media was selected among three bacterial candidates based on the enzymatic examinations. Results showed that H16 does not need oxygen for urea hydrolysis and urease activity was determined primarily by cell concentration. However, the additional urea in the combined medium slowed down the nitrate reduction rate to 7 days until full NO3−decomposition. Moreover, the nitrate reduction of H16 was significantly restricted by an increased Ca2+ion concentration in the media. Nevertheless, the overall CaCO3precipitation yield can be improved by 20 to 30% after optimization through the combination of two metabolic pathways. The highest total CaCO3precipitation yield achieved in an orthogonal experiment was 14 g/L. It can be concluded thatRalstonia eutrophaH16 is a suitable bacterium for simultaneous activation of urea hydrolysis and nitrate reduction for improving the CaCO3precipitation and it can be studied later, on activation of multiple metabolic pathways in bacteria-based self-healing concrete.