Development of bioprocesses for the biocementation microorganism $Sporosarcina$ $pasteurii$.

This thesis focuses on optimizing the cultivation and urease production of Sporosarcina pasteurii , a bacterium commonly used for Microbial-Induced Calcite Precipitation (MICP), a process with high potential in the fields of construction, geotechnical engineering, and environmental remediation. This work primarily focuses on addressing the limitations of current cultivation methods and introducing effective cultivation protocols for S. pasteurii . While not the immediate goal of this work, optimizing cultivation could contribute to reducing the production costs of ureolytic biomass in the long term, thereby potentially aiding in making the application of MICP more economically feasible. Firstly, by employing a chemically defined medium, the batch cultivation of S. pasteurii is improved through the identification and supplementation of auxotrophic deficiencies (L-methionine, L-cysteine, thiamine, and nicotinic acid) and nutritional requirements (phosphate and trace elements) of the bacterium. Additionally, beneficial carbon sources (glucose, maltose, lactose, fructose, sucrose, acetate, L-proline, and L-alanine) are identified and utilized as well. After improving said medium, common complex media based on peptone and yeast extract were supplemented based on these findings. The improved culture medium based on yeast extract results in fourfold higher OD600 of 26.6 at the end of cultivation. Culture performance and media improvement was analysed by measuring the oxygen transfer rate as well as the backscatter during shake flask cultivation. The thesis also presents a novel urease activity microplate assay, based on a fluorescent pH indicator, to automate urease activity measurements during microbioreactor experiments. This approach was found to be reliable, cost-effective, and unaffected by the turbidity, salinity, or buffer concentration of the sample. The thesis then explores fed-batch cultivation of S. pasteurii , distinguishing between limited fed-batch cultivation and extended batch cultivation. This ...