Genomic trends on the biogenic CaCO₃ production in the genus Bacillus

The biogenic production of CaCO₃ via Microbially Induced Calcite Precipitation (MICP) has been reported in many microbial strains. This process has a wide variety of current and potential applications, namely in civil engineering, agriculture and bio-remediation. The number of species used in such applications remains limited and seems to be biased towards ureolytic strains. Urea degradation is the best documented process leading to MICP, however, there are several alternative processes, possibly more relevant, which are mostly overlooked. In general, and despite being widely reported, the MICP process is still poorly understood, and has been chronically understudied from a genomic perspective. Here we report on the genus-wide analysis of MICP capability, centred on genomic-based analysis, and focusing on the genus Bacillus. This genus harbours several species capable of MICP and is the most widely used regarding its biotechnological application. The very high number of species within this genus, and availability of whole genome sequence data for several makes it an ideal target for this analysis. Our preliminary results uncover a diverse range of MICP-associated genes, identifies similar genomic profiles within phylogenetic subgroups, and questions the importance of urease activity for CaCO₃ production in the genus Bacillus. This study is the first of its kind and provides key insights into the genomic basis of MICP, while testing the feasibility of a genomic-based prediction method for fast identification of new strains with such capabilities, which would be applicable to other genera and be particularly useful for downstream applications.