Description

The aim of the project is the development of a continuously operated bioreactor for the electrode-based fermentation of platform chemicals. Here, optimal carbon utilisation and high space-time yields are a clear benchmark compared to classical batch fermentations. The exoelectrogenic proteobacterium Shewanella oneidensis is to be adapted for this purpose as a stable production organism with the ability to form a conductive biofilm on anodes. For the adaptation, the organism is to be stabilised with the help of CRISPR/Cas genome editing. For cultivation, a scalable bioreactor with adapted electrodes will be designed and constructed to guarantee both optimal biofilm growth and very good electron transfer between bacteria and electrode material. Anaerobic fermentations are highly desirable in biotechnological production processes. However, there are many products in which the carbon has a higher oxidation state than in the substrate. To provide electron acceptors for this, anodes are perfectly suited because they can be regulated over a wide range. The prerequisite for this is exoelectrogenic biofilm-forming production strains that generate an electric current in parallel. This type of cultivation has high potential for the future, but production rates are currently still too low, also due to a lack of scalable bioreactors.

Three research hypotheses drive the project:

1. It is possible to modify S. oneidensis to the extent that the organism forms stable conductive anode biofilms with which high space-time yields can be achieved.
2. Bioelectrochemical production is the method of choice for continuously operated fermentations in the future.
3. Scalable bioreactors for bioelectrochemical fermentation will take biotechnological production of platform chemicals to a new level.