Two-Stage Environmental Response of Sporosarcina pasteurii: Stepwise Alkaline–Low-NaCl Exposure and Subsequent Temperature Challenge

Microbially induced calcium carbonate precipitation (MICP) is influenced by the physiological response of ureolytic bacteria to local environmental backgrounds. This liquid-culture process-screening study examined responses of Sporosarcina pasteurii ATCC 11859 under combined alkaline–low-NaCl backgrounds and elevated temperatures relevant to inland aeolian-sand environments. Cultures were sequentially exposed to five pH-NaCl backgrounds at 30 °C, followed by temperature treatments (35–41 °C) under three selected backgrounds. Cell density (OD600), urease activity, and apparent dry precipitate mass (ADPM), used as an operational dry-residue endpoint, were measured. Temperature, pH–NaCl background, and their interaction significantly affected urease activity and OD600, whereas ADPM showed a significant temperature effect but was not interpreted as quantitative CaCO3 production. A composite analysis indicated that pH 9.3, 1.4‰ NaCl and 35–37 °C represented a coordinated liquid-culture response range. At pH 9.3, 1.4‰ NaCl, and 37 °C, urease activity, OD600, and ADPM were 1.155 mM urea min−1, 1.662, and 1.14 g, respectively. Overall, the identified range provides a practical liquid-culture basis for subsequent sand-tray stabilization tests under aeolian-sand conditions.