Production of Biocement Using a Shelf-Stable Formulation of the Soil Bacterium Sporosarcina pasteurii at Laboratory and Field-Scales for Ground Improvement

Manufacturing of traditional cementitious materials is an energy-intensive and unsustainable process. Cement is the third largest source of anthropogenic carbon dioxide emissions globally, accounting for an estimated 8% of emissions. To help mitigate the environmental impacts of cement and concrete, more environmentally-friendly materials are needed. Biocement shares many similar physical properties with traditional cement and may be useful as an alternative material for a variety of applications in construction and the development of infrastructure. It is produced via microbially-induced biomineralization of calcite. <i>Sporosarcina pasteurii </i>is a soil bacterium that has emerged as the model organism for biocement production. While there has been considerable interest in biocement as a green material, producing it at industrial scales is challenging and there is a lack of ready-mix formulas similar to those that exist for traditional cement. Here we developed a shelf-stable preparation of <i>S. pasteurii</i> that has been preserved via lyophilization. At the laboratory-scale, we see that this formulation performs similarly to live cell cultures, precipitating an equivalent amount of calcite and resulting in biocement with the same level of mechanical strength. We further demonstrate the applicability of this formulation at precipitating calcite under non-ideal conditions in the field, leading to <i>in situ </i>production of biocement with increased bearing capacity of the ground. The strength and depth of cementation achieved using this formulation can be modulated by altering the treatment regime used in biocement production. Altogether, these results indicate that stabilized preparations of bacteria are a viable means by which biocement may be manufactured. This is advantageous as it has the potential to be used as a ready-mix formula for the creation of biocement that is accessible to nontechnical professionals. Shelf-stable formulas such as this will make the process of biocement production easier, paving the way for more widespread adoption of biocement as a construction material as the technology surrounding it continues to mature.