Periodic Reporting for period 1 - ECOMO (Electrobiocatalytic cascade for bulk reduction of CO2 to CO coupled to fermentative production of high value diamine monomers)
Reporting period: 2023-11-01 to 2024-10-31
Innovation gate 2: The project participants from the Technical University of Denmark (DTU) have completed the development of microbial consortia adapted to CO and have finalized the planning of all activity tests to indicate how CO-adapted microbial consortia are superior in consuming CO to the non-adapted consortia. The microbial consortia showed a high selectivity for acetic acid production under the enrichment conditions. The development of electron mediating consortia will occur with CO-adapted consortia as starting inoculum and is expected to be completed very soon. The DTU partners have also started up two trickle bed reactors, TBR, and adapted them for CO, while they have started optimization tests towards achieving higher selectivity. Operation of trickle bed reactors and adaptation to CO showed a selectivity for acetate lying between 76 – 90 %. An optimization strategy for increasing the acetate selectivity of the acetate switch, including the elimination of micronutrients necessary for ethanol generation, in-situ acetate removal, and operation at thermophilic temperature, is expected to boost the selectivity and reach the KPI (Key Performance Indicator) of 95% acetate selectivity.
Innovation gate 3: The work of the third innovation gate of ECOMO aims at the renewable production of plastic polymer precursors such as diamines and diols from CO--2-derived acetate provided by innovation gates 1 and 2 and recycled nitrogen flows. The commonly established industrial host microorganism Corynebacterium glutamicum fermentatively produces the industrially important and useful monomers. The TUM-MIB and Fraunhofer-SCP project partners focused on several tasks to jointly generate new and optimized available production strains for high production performance on acetate. Therefore, the genetic toolbox of C. glutamicum was extended to facilitate more efficient construction of high-yielding strains. Moreover, based on computer-generated predictions, a compressed metabolic model of the organism’s core metabolism was built and used to simulate diol and diamine production and direct strain construction. Also, available first-generation diamine producers were adapted for production on acetate, and initial producer strains are now ready for early-stage scale-up experiments and process development.
Innovation gate 1: Previous redox-active polymers synthesized by the project partner TUM-EBT exhibited reduction potentials of -0.25 V and -0.4 V versus SHE, which are too positive to mediate electrons for CO2 reduction by CODH enzymes. With the design and successful synthesis of novel redox-active polymers with reduction potentials negative enough to mediate electrons between the CODH enzyme and CO2 in a CO2 electrolyzer, the project is advancing forward in the realm of bioelectrochemical CO2 reduction
Innovation gate 2: Reaching the KPI of 95% acetate selectivity is expected to boost further application of mixed microbial consortia-based gas fermentations, which nowadays is limited to methane production at industrial scale. Demonstrating production of acetate from CO with high selectivity by mixed microbial consortia will constitute a significant scientific impact – especially as CO is a well-known substrate favoring ethanol production in gas fermentations.
Innovation gate 3: Corynebacterium glutamicum was enabled to produce a diamine from acetate using metabolic engineering. The substrate spectrum of available diamine producer strains was extended to acetate as carbon source by rewiring the central metabolism. Within the ECOMO cascade acetate has high potential to be produced regeneratively directly from CO2. Thereby, a sustainable/carbon neutral feedstock for diamine production can be delivered. To complete the ECOMO process cascade and fully achieve the regenerative production of diamines from CO2 and recycled nitrogen flows, further research is needed.