氮同化细菌Sulfitobacter sp. IGS-18在MICP过程中去除铵离子的研究

Study on Ammonium Ion Removal by Nitrogen Assimilating Bacteria Sulfitobacter sp. IGS-18 in MICP Process

摘要: 微生物诱导碳酸钙沉淀(MICP)技术在应用中面临副产物氨氮污染的问题。本研究以一株兼具脲酶、谷氨酸脱氢酶(GDH)和谷氨酰胺合成酶(GS)活性的亚硫酸盐杆菌Sulfitobacter sp. IGS-18为对象，系统探究其铵离子去除的酶学基础与分子机制。结果表明，该菌株GDH和GS酶的最适反应条件均为pH 8.5和40℃，在高铵环境中GDH活性迅速响应，GS则持续发挥氨同化作用。铵离子去除实验显示，与“产氨”菌株S. pasteurii相比，生物矿化过程中IGS-18在6 h内实现的$N{H}_4^{+}-N$ 的去除效率达90.1%。全基因组测序揭示其拥有脲酶基因簇ureABCEFGD、谷氨酸脱氢酶基因(gdhA)和谷氨酰胺合成酶基因(glnA)，以及GS-GOGAT循环相关基因，为高效氨同化提供了基础。本研究从酶学与基因组学层面阐明了Sulfitobacter sp. IGS-18的铵离子去除机理，为开发环境友好型MICP技术提供了理论依据和优良菌种资源。

Abstract: Microbial induced calcium carbonate precipitation (MICP) technology faces the problem of ammonia nitrogen pollution as a byproduct. This study used Sulfitobacter sp. IGS-18, a sulfite bacterium with urease, glutamate dehydrogenase (GDH), and glutamine synthetase (GS) activities, to systematically explore the enzymatic basis and molecular mechanism of its ammonium ion removal. The results showed that the optimal reaction conditions for GDH and GS enzymes in this strain were pH 8.5 and 40˚C. In a high ammonium environment, GDH activity responded rapidly, while GS continuously exerted its ammonia assimilation effect. Ammonium ion removal experiments showed that, compared with the ammonia-producing strain S. pasteurii, IGS-18 achieved a 90.1% $N{H}_4^{+}-N$ removal efficiency within 6 h during the biomineralization process. Whole-genome sequencing revealed that it possesses the urease gene cluster ureABCEFGD, the glutamate dehydrogenase gene (gdhA), and the glutamine synthase gene (glnA), as well as GS-GOGAT cycle-related genes, providing a foundation for efficient ammonia assimilation. This study elucidated the ammonium ion removal mechanism of Sulfitobacter sp. IGS-18 from an enzymological and genomic perspective, providing a theoretical basis and excellent strain resources for the development of environmentally friendly MICP technology.