Ca-mediated alleviation of Cd²⁺ induced toxicity and improved Cd²⁺ biomineralization by Sporosarcina pasteurii

• Main Authors: Fang, Longyang, Niu, Qijian, Cheng, Liang, Jiang, Jianxiong, Yu, Yang-Yang, Chu, Jian, Achal, Varenyam, You, Tianyan
• Other Authors: School of Civil and Environmental Engineering
• Format: Article
• Language: English
• Published: 2022
• Subjects: Engineering::Environmental engineering; Microbial Induced Carbonate Precipitation; Biomineralization
• Online Access: https://hdl.handle.net/10356/159725
• Institution: Nanyang Technological University

Microbial induced carbonate precipitation has been widely used in the biomineralization of heavy metals Cd2+. However, the low Cd-tolerance of ureolytic bacteria limits the applications with only low Cd2+concentrations. In this study, we discovered a simple approach to significantly enhance the Cd2+ resistance of ureolytic bacteria through an immediate supplement of Ca2+. The Ca2+ protected the cells by reducing the extracellular and intracellular Cd2+ concentration by about 50%. As a result, the Cd2+ removal efficiency was notably improved by about 100% (52.72% to 99.43%, Cd = 5 mM) with Ca2+ supplement. Moreover, extremely high concentration of Cd2+ could be almost completely removed (99.46% at C0 = 20 mM and 99.60% at C0 = 50 mM) within 24 h. Microstructure analyses indicated that the mineralized precipitates were rhombohedral-shaped CdCO3, CaCO3, and (Ca0.67, Cd0.33)CO3. Furthermore, Ca2+ could also protect ureolytic bacteria against toxicity from other heavy metals.