Enhanced calcium carbonate-biofilm complex formation by alkali-generating Lysinibacillus boronitolerans YS11 and alkaliphilic Bacillus sp. AK13

Microbially induced calcium carbonate (CaCO₃) precipitation (MICP) is a process where microbes induce condition favorable for CaCO₃ formation through metabolic activities by increasing the pH or carbonate ions when calcium is near. The molecular and ecological basis of CaCO₃ precipitating (CCP) bacteria has been poorly illuminated. Here, we showed that increased pH levels by deamination of amino acids is a driving force toward MICP using alkalitolerant Lysinibacillus boronitolerans YS11 as a model species of non-ureolytic CCP bacteria. This alkaline generation also facilitates the growth of neighboring alkaliphilic Bacillus sp. AK13, which could alter characteristics of MICP by changing the size and shape of CaCO₃ minerals. Furthermore, we showed CaCO₃ that precipitates earlier in an experiment modifies membrane rigidity of YS11 strain via upregulation of branched chain fatty acid synthesis. This work closely examines MICP conditions by deamination and the effect of MICP on cell membrane rigidity and crystal formation for the first time.