Screening of bacteria for self-healing of concrete cracks and optimization of the microbial calcium precipitation process

• Published in: Applied microbiology and biotechnology Vol. 100; no. 15; pp. 6661 - 6670
• Main Authors: Zhang, J. L., Wu, R. S., Li, Y. M., Zhong, J. Y., Deng, X., Liu, B., Han, N. X., Xing, F.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-08-2016; Springer; Springer Nature B.V
• Subjects: Bacillus; Bacillus - genetics; Bacillus - metabolism; Bacteria; Biomedical and Life Sciences; Biotechnological Products and Process Engineering; Biotechnology; Calcium; Calcium - chemistry; Calcium Carbonate - chemistry; Calcium, Dietary; Carbon; Chemical properties; Civil engineering; Concrete; Construction Materials - microbiology; Cracks; DNA sequencing; Environmental impact; Genetic aspects; High-throughput screening (Biochemical assaying); Laboratories; Life Sciences; Measurement techniques; Methods; Microbial Genetics and Genomics; Microbiology; Mineralization; Nitrogen sources; Nucleotide sequencing; Optimization; Precipitation (Chemistry); Respiration; RNA, Ribosomal, 16S - genetics; Sediments; Studies; Concrete crack; Alkaliphilic bacteria; Self-healing; Calcium precipitation; sp; Bacillus sp
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-016-7382-2

A novel high-throughput strategy was developed to determine the calcium precipitation activity (CPA) of mineralization bacteria used for self-healing of concrete cracks. A bacterial strain designated as H4 with the highest CPA of 94.8 % was screened and identified as a
Bacillus
species based on 16S rDNA sequence and phylogenetic tree analysis. Furthermore, the effects of certain influential factors on the microbial calcium precipitation process of H4 were evaluated. The results showed that lactate and nitrate are the best carbon and nitrogen sources, with optimal concentrations of approximately 25 and 18 mM, respectively. The H4 strain is able to maintain a high CPA in the pH range of 9.5–11.0, and a suitable initial spore concentration is 4.0 × 10
7
spores/ml. Moreover, an ambient Ca
2+
concentration greater than 60 mM resulted in a serious adverse impact not only on the CPA but also on the growth of H4, suggesting that the maintenance of the Ca
2+
concentration at a low level is necessary for microbial self-healing of concrete cracks.