Chen Meiqi, Gowthaman Sivakumar, Nakashima Kazunori, Takano Chikara, Kawasaki Satoru
Laboratory of Biotechnology for Resources Engineering, Graduate School of Engineering, Hokkaido University, Sapporo, Japan.
Department of Engineering Technology, Faculty of Technology, University of Jaffna, Kilinochchi, Sri Lanka.
Front Bioeng Biotechnol. 2023 Jun 14;11:1216171. doi: 10.3389/fbioe.2023.1216171. eCollection 2023.
Microbial induced carbonate precipitation (MICP) through the ureolysis metabolic pathway is one of the most studied topics in biocementation due to its high efficiency. Although excellent outcomes have proved the potential of this technique, microorganisms face some obstacles when considering complicated situations in the real field, such as bacterial adaptability and survivability issues. This study made the first attempt to seek solutions to this issue from the air, exploring ureolytic airborne bacteria with resilient features to find a solution to survivability issues. Samples were collected using an air sampler in Sapporo, Hokkaido, a cold region where sampling sites were mostly covered with dense vegetation. After two rounds of screening, 12 out of 57 urease-positive isolates were identified through 16S rRNA gene analysis. Four potentially selected strains were then evaluated in terms of growth pattern and activity changes within a range of temperatures (15°C-35°C). The results from sand solidification tests using two strains with the best performance among the isolates showed an improvement in unconfined compressive strength up to 4-8 MPa after treatment, indicating a high MICP efficiency. Overall, this baseline study demonstrated that the air could be an ideal isolation source for ureolytic bacteria and laid a new pathway for MICP applications. More investigations on the performance of airborne bacteria under changeable environments may be required to further examine their survivability and adaptability.
通过尿素分解代谢途径的微生物诱导碳酸盐沉淀（MICP）因其高效性而成为生物胶结领域研究最多的课题之一。尽管出色的成果证明了该技术的潜力，但在考虑实际现场的复杂情况时，微生物面临一些障碍，例如细菌的适应性和生存能力问题。本研究首次尝试从空气中寻找解决该问题的方法，探索具有弹性特征的尿素分解性空气传播细菌，以找到生存能力问题的解决方案。在北海道札幌市使用空气采样器采集样本，该市是一个寒冷地区，采样地点大多覆盖着茂密的植被。经过两轮筛选，通过16S rRNA基因分析从57株尿素酶阳性分离株中鉴定出12株。然后在一系列温度（15°C - 35°C）范围内对4株潜在选择的菌株进行生长模式和活性变化评估。使用分离株中性能最佳的两株菌株进行的砂固化试验结果表明，处理后无侧限抗压强度提高到4 - 8 MPa，表明MICP效率很高。总体而言，这项基础研究表明空气可能是尿素分解细菌的理想分离来源，并为MICP应用开辟了一条新途径。可能需要对可变环境下空气传播细菌的性能进行更多研究，以进一步考察它们的生存能力和适应性。
