Golovkina Darya A, Zhurishkina Elena V, Ivanova Lyubov A, Baranchikov Alexander E, Sokolov Alexey Y, Bobrov Kirill S, Masharsky Alexey E, Tsvigun Natalia V, Kopitsa Gennady P, Kulminskaya Anna A
Petersburg Nuclear Physics Institute Named by B.P. Konstantinov of National Research Centre "Kurchatov Institute", 188300 Gatchina, Russia.
Kurchatov Genome Centre-PNPI, 188300 Gatchina, Russia.
Life (Basel). 2020 Nov 28;10(12):317. doi: 10.3390/life10120317.
Microbially induced CaCO precipitation (MICP) is considered as an alternative green technology for cement self-healing and a basis for the development of new biomaterials. However, some issues about the role of bacteria in the induction of biogenic CaCO crystal nucleation, growth and aggregation are still debatable. Our aims were to screen for ureolytic calcifying microorganisms and analyze their MICP abilities during their growth in urea-supplemented and urea-deficient media. Nine candidates showed a high level of urease specific activity, and a sharp increase in the urea-containing medium pH resulted in efficient CaCO biomineralization. In the urea-deficient medium, all ureolytic bacteria also induced CaCO precipitation although at lower pH values. Five strains ( DSMZ 8782, 4b, 4a, BS52, 6) were found to completely repair micro-cracks in the cement samples. Detailed studies of the most promising strain DSMZ 8782 revealed a slower rate of the polymorph transformation in the urea-deficient medium than in urea-containing one. We suppose that a ureolytic microorganism retains its ability to induce CaCO biomineralization regardless the origin of carbonate ions in a cell environment by switching between mechanisms of urea-degradation and metabolism of calcium organic salts.
微生物诱导碳酸钙沉淀（MICP）被认为是一种用于水泥自修复的绿色替代技术，也是新型生物材料开发的基础。然而，关于细菌在生物成因碳酸钙晶体成核、生长和聚集诱导过程中的作用的一些问题仍存在争议。我们的目的是筛选尿素分解钙化微生物，并分析它们在补充尿素和缺乏尿素的培养基中生长期间的MICP能力。九种候选微生物表现出高水平的脲酶比活性，含尿素培养基pH值的急剧升高导致了高效的碳酸钙生物矿化。在缺乏尿素的培养基中，所有尿素分解细菌也能诱导碳酸钙沉淀，尽管pH值较低。发现五株菌株（DSMZ 8782、4b、4a、BS52、6）能完全修复水泥样品中的微裂纹。对最有前景的菌株DSMZ 8782的详细研究表明，在缺乏尿素的培养基中多晶型转变的速率比在含尿素的培养基中慢。我们推测，尿素分解微生物通过在尿素降解机制和钙有机盐代谢之间切换，无论细胞环境中碳酸根离子的来源如何，都保留其诱导碳酸钙生物矿化的能力。
