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Background  The ureolytic bacterium  Sporosarcina pasteurii  is well-known for its capability of microbially induced calcite precipitation (MICP), representing a great potential in constructional engineering and material applications. However, the molecular mechanism for its biomineralization remains unresolved, as few studies were carried out.    Results  The addition of urea into the culture medium provided an alkaline environment that is suitable for  S .  pasteurii.  As compared to  S. pasteurii  cultivated without urea , S. pasteurii  grown with urea showed faster growth and urease production, better shape, more negative surface charge and higher biomineralization ability. To survive the unfavorable growth environment due to the absence of urea,  S. pasteurii  up-regulated the expression of genes involved in urease production, ATPase synthesis and flagella, possibly occupying resources that can be deployed for MICP. As compared to non-mineralizing bacteria,  S. pasteurii  exhibited more negative cell surface charge for binding calcium ions and more robust cell structure as nucleation sites. During MICP process, the genes for ATPase synthesis in  S. pasteurii  was up-regulated while genes for urease production were unchanged. Interestingly, genes involved in flagella were down-regulated during MICP, which might lead to poor mobility of  S. pasteurii.  Meanwhile, genes in fatty acid degradation pathway were inhibited to maintain the intact cell structure found in calcite precipitation. Both weak mobility and intact cell structure are advantageous for S . pasteurii  to serve as nucleation sites during MICP.    Conclusions  Four factors are demonstrated to benefit the super performance of  S. pasteurii  in MICP. First, the good correlation of biomass growth and urease production of  S. pasteurii  provides sufficient biomass and urease simultaneously for improved biomineralization. Second, the highly negative cell surface charge of  S. pasteurii  is good for binding calcium ions. Third, the robust cell structure and fourth, the weak mobility, are key for  S. pasteurii  to be nucleation sites during MICP.

Beneficial factors for biomineralization by ureolytic bacterium Sporosarcina pasteurii