Low-cost cultivation of Sporosarcina pasteurii strain in food-grade yeast extract medium for microbially induced carbonate precipitation (MICP) application

Sporosarcina pasteurii is a well-known ureolytic microbial species that proficiently induces the deposition of calcium carbonate through microbially induced carbonate precipitation (MICP) process for various biotechnological and engineering purposes. In view to resolving the concern on high-cost bacterial cultivation due to the conventional use of laboratory-grade growth medium for MICP studies, an inexpensive food-grade yeast medium was investigated in this current study for its feasibility to serve as a suitable alternative media for bacterial growth, urease activity and calcium carbonate precipitation. The effect of different media concentration and initial pH medium on biomass production and urease activity were determined. The performance of this low-cost media was also compared with eight laboratory-grade media (nutrient broth, yeast extract, tryptic soy broth, luria broth, fluid thioglycollate medium, cooked meat medium, lactose broth and marine broth). Results in this current study showed cultivation in low-cost media at 15 g L-1 (w/v) and initial pH 8.5 of the food-grade yeast media both constituted the highest biomass concentration and urease activity when supplemented with urea (4%, w/v). Comparison of the food-grade media with laboratory-grade media indicated that bacterial cultivation cost was significantly reduced to 99.80%. After the biomineralization test, X-ray diffraction (XRD) analysis was used to confirm the elemental composition of CaCO3 and polymorphs which were identified as calcite and vaterite. These findings suggest the food-grade yeast extract can serve as a potential candidate for bacterial cultivation in MICP application from the perspective of cost reduction.