微生物诱导碳酸钙沉积对土壤细菌群落的影响及其表型与功能预测

Effects of microbially induced calcium carbonate precipitation on soil bacterial communities, predictions of phenotypic and functional characteristics

  • 摘要: 微生物诱导碳酸钙沉积技术(microbially induced carbonate precipitation, MICP)在土壤固化中应用广泛, 但其对细菌群落结构与功能的长期影响尚不明确。本研究通过喷洒巴氏生孢八叠球菌(Sporosarcina pasteurii)和胶结液(尿素+CaCl2溶液)处理土壤, 结合高通量测序与表型和基因功能预测, 解析MICP对土壤理化性质及微生物群落的调控机制。结果表明, MICP处理显著提升土壤pH (从7.62提升至7.94)、碱解氮(从67mg·kg−1提升至1603 mg·kg−1)及氯离子浓度(从377mg·kg−1提升至26 679 mg·kg−1), 并诱导碳酸钙沉积。微生物α多样性指数Shannon显著降低, 群落结构趋同, 厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidota)相对丰度分别从3.31%和1.68%激增至12.73%和6.78%, 而变形菌门(Proteobacteria)和放线菌门(Actinobacteriota)则分别从48.56%和25.53%降至41.61%和19.17%。其中溶杆菌属(Lysobacter)与生孢八叠球菌属(Sporosarcina)成为核心功能类群, 其富集与生物膜形成、脲酶活性及耐盐碱基因表达密切相关。冗余分析与网络拓扑揭示, Ca2+、碱解氮(AHN)与pH构成群落分异的驱动框架, 累计解释66.51%的变异。功能预测显示, MICP组DNA复制、能量代谢等核心通路活性下降15%~35%, 但生物膜形成与抗逆表型显著增强。研究表明, MICP通过高钙-高氯-碱性环境筛选耐逆功能菌, 但可能牺牲土壤生态功能多样性。本研究为MICP技术的生态安全评估与工艺改进提供了理论依据。

     

    Abstract: Microbially induced carbonate precipitation (MICP) is widely applied in soil stabilization, yet its long-term impacts on bacterial community structure and function remain unclear. This study investigated the regulatory mechanisms of MICP on soil physicochemical properties and microbial communities by spraying Sporosarcina pasteurii and cementation solutions (urea + CaCl2) combined with high-throughput sequencing, phenotypic prediction, and genomic functional analysis. The results demonstrated that MICP significantly increased soil pH (from 7.62 to 7.94), alkali-hydrolyzable nitrogen (AHN: from 67 to 1 603 mg·kg−1), and chloride ion concentration (from 377 to 26 679 mg·kg−1), while inducing calcium carbonate deposition. The Shannon diversity index decreased significantly, and microbial community structure converged, with the relative abundances of Firmicutes and Bacteroidota increasing from 3.31% and 1.68% to 12.73% and 6.78%, respectively, while Proteobacteria and Actinobacteriota decreased from 48.56% and 25.53% to 41.61% and 19.17%. Core functional taxa, including Lysobacter and Sporosarcina, were significantly enriched, driven by biofilm formation, urease activity, and salt-alkali tolerance gene expression. Redundancy analysis and network topology revealed that Ca2+, AHN, and pH formed a driving framework for community differentiation, explaining 66.51% of the variation. Functional predictions indicated suppressed core metabolic pathways (e.g., DNA replication and energy metabolism, reduced by 15%–35%) but enhanced biofilm formation and stress-resistant phenotypes in the MICP group. This study demonstrates that MICP screens for stress-resistant functional bacteria through a high-calcium, high-chloride, and alkaline environment, but it may sacrifice the diversity of soil ecological functions. These findings provide a theoretical basis for ecological risk assessment and process optimization of MICP technology.

     

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