Exploiting Bacillus subtilis as production platform for antimicrobial compounds using mersacidin as an exemplary product

• Applicant: Dr. Lars Lilge
• Subject Area: Biological Process Engineering
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 501222601

The production of effective antimicrobial substances is necessary at a time when the development of new antibiotics is limited. For screening novel substances, Bacillus subtilis seems to be a promising production organism, which has already been established as a workhorse for industrially and pharmaceutically useful proteins and fine chemicals. To realize strategies for the production of antimicrobial substances such as lantibiotics, mersacidin as a representative of peptide antibiotics will be studied with two promising B. subtilis production strains, namely high cell-density strain 3NA and the genome-reduced miniBacillus PG10. Different strategies for continuous and inducible mersacidin production will be carried out with the aim of achieving the highest possible mersacidin titres. The integration of different systems to uncouple mersacidin production and its activation, but also to uncouple cell growth and mersacidin production, should help to increase the final titres and improve the availability of bacterially produced antimicrobial substances. These strategies will be tested in different adapted fed-batch bioreactor cultures that ensure controlled mersacidin production over time, by induction of mersacidin production after reaching high biomass or time-defined mersacidin activation after a previous production phase. The investigation of different strategies for the upscaled production of mersacidin, such as feed-directed antibiotic production or inducible extracellular activation of the antibiotic, is intended to identify best possible process designs for heterologous production of antimicrobial substances and is representative of the use of B. subtilis as a production organism for innovative antibiotics from nature.A second point of the proposal addresses the immunity of the production strains. Therefore, the bacterial detoxification and immunity mechanisms will be analysed in different approaches. It is known that B. subtilis exhibits several specific and non-specific defence strategies such as lantibiotic transporters. These findings will be used for the construction of more robust and tolerant production strains for the formation of antimicrobial substances, specifically for lantibiotics such as mersacidin.

• DFG Programme: WBP Fellowship
• International Connection: Netherlands
• Host: Professor Dr. Oscar P. Kuipers