Project Details
Projekt
Tunable electro-fermentation using metabolically engineered Pseudomonas putida
Applicants
Dr. Jens Krömer; Professor Dr. Christoph Wittmann
Subject Area
Biological Process Engineering
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 445908911
The overall objective of the project ePseudomonas is the development of an efficient bio-electrochemical platform which uses metabolically engineered strains of the soil bacterium Pseudomonas putida to produce commercially attractive acids, keto-acids, and aldaric acids. The conversion will be operated in a bio-electrochemical system, which is driven by an electron flow from cytochromes of the microbe via externally added non-toxic mediators to an anode. As shown by us in previous work, this set-up provides 2-ketogluconate (from glucose) at attractive yield, forms p-hydroxybenzoate (from citrate) even more efficient than a conventional aerobic process and promises to catalyze a range of other conversions of relevance. The concept of external mediators has several advantages over potential alternatives, such as self-synthesized mediators or biofilm-based approaches: (i) the mediator amount is externally controllable, (ii) a metabolic burden for mediator synthesis can be avoided, (iii) the redox potential and hence the driving force can be chosen from a spectrum of mediators, and (iv) it enables planktonic reactor set-ups for facilitated scale-up in the future. Interestingly, it allows a completely anoxic metabolism of P. putida, known as an obligate aerobic bacterium and so far, exclusively used in aerated processes. In order to reach this ambitious goal, ePseudomonas will address five specific objectives: (i) to implement systems biology analysis of bio-electrochemically driven cells on the level of transcriptome, proteome, metabolome, and fluxome, (ii) to achieve a detailed quantitative understanding of the largely uncharacterized electrogenic lifestyle of the microbe in iterative design-build-test-learn cycles, (iii) to design and construct P. putida mutants for hypothesis testing and step-wise improvement of electrogenic performance using synthetic biology, (iv) to screen various sugar and non-sugar substrates of relevance for their conversion into the corresponding acids, keto-acids, and aldaric acids, and (v) to design and establish a sophisticated bio-process at lab scale for evaluation of the developed strains and demonstration. For this purpose, the two partners involved will build on previous efforts in electro-biotechnology and combine their complementary expertise in bio-electrochemistry (Krömer lab, UFZ Leipzig) and systems metabolic engineering (Wittmann lab, Saarland University).
DFG Programme
Priority Programmes
