Optimising protein production from high density Bacillus subtilis cultures by supressing autolysis

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The Gram-positive bacterium Bacillus subtilis is a highly amenable industrial production host used to produce numerous commercially valuable enzymes. The prominent role of B. subtilis in industrial production of recombinant proteins is based on the ease with which its genome can be engineered (more recently including the CRISPR technology), and the ability to produce high yields of protein by secretion directly to the extracellular medium thereby facilitating cost-effective purification. In addition to being an industrial production host, B. subtilis is among the best-studied bacterial model organism. One of the reasons for this is its characteristic cell differentiation processes that result in distinct sub-populations of cells that enter distinct cellular differentiation pathways. However, the ability to differentiate into district sub-population has negative consequences for the function of B. subtilis as a protein production host as not all of the resulting cell types contribute to the protein production process. In this joint biotechnology-themed research project between Newcastle University and Royal DSM, we will determine how the fitness of B. subtilis, in terms of its energy status during industry-like fermentation conditions, can be optimised for improved heterologous protein production. A specific focus will be on studying the cell autolytic process, which affects a significant proportion of the cell population and thus reduces the protein production yield. How the fermentation conditions can be optimised to minimise autolysis, and how the production host can be re-engineered to suppress the autolytic process will be studied with the ultimate goal to improve recombinant protein production.The interdisciplinary project combines state-of-the-art techniques in molecular and cellular biology including molecular cloning and high-end microscopy, and biotechnological methods including production host optimisation, fermentation, and recombinant protein production. The PhD programme is carried out at the Centre for Bacterial Cell Biology (Newcastle University), a world-class research centre with focus on microbiology. Regular research stays with the industrial partner at the DSM Biotechnology Center (Delft, the Netherlands) form an integral part of the research programme.