Building bridges; strategies to improve disulfide bond formation in the Bacillus subtilis platform for recombinant protein production
Building bridges: strategies to improve disulfide bond formation in the Bacillus subtilis platform for recombinant protein production
Bacillus subtilis is a cosmopolitan, Gram-positive, rod-shaped soil bacterium, known to be non-pathogenic and able to adapt to a broad range of biotopes. Its claim to fame came not only from being one of the first organisms to have their genome fully sequenced or from being an amenable model organism for studies on Gram-positive bacteria, but also from its undeniable position as a workhorse for industrial biotechnological applications. This bacterium has made its name in producing large quantities of industrial enzymes, among other biomolecules, which it can secrete directly into the fermentation broth, allowing for cost-effective processes.
In this thesis of Jonathan Walgraeve, efforts are presented to further expand on these strengths. The results showcase the potential of genome-reduced B. subtilis strains in industrial fermentations and how these strains metabolize complex growth media compared to strains with non-reduced genomes. Furthermore, a screening method is presented which, by use of diamide, significantly reduces the laboriousness of finding desired phenotypes resistant to oxidative stress. When coupled with a suitable cysteine-rich recombinant protein to express, the screening method can be adapted to find phenotypes capable of producing higher quantities of said protein in a direct screening approach.
Finally, strategies are presented to increase the portfolio of recombinant proteins which can be qualitatively produced by B. subtilis, namely disulfide bond-containing proteins, through the introduction of thiol-disulfide oxidoreductases from other Gram-positive bacteria. With these results another step is made towards a more sustainable future with the sustained presence of our favourite industrial workhorse, B. subtilis.