(554g) [Keynote] Strain and Bioprocess Engineering to Enhance and Investigate Carbon Efficient Biochemical Production

Using metabolic engineering and synthetic biology tools/strategies, our group focusses on developing novel microbes capable of producing value-added chemicals with bulk, specialty, and even nutritional applications. Meanwhile, to drive production metrics and minimize wasted carbon, a key, current focus is on the use or reuse of CO₂ as (co-)substrate. This objective, however, is met by several technical and analytical challenges resulting from the low and pH-dependent aqueous solubility of CO₂. Accordingly, we have also been exploring novel bioprocess designs aimed at enhancing CO₂ delivery or promoting its in situ recycling. As one approach, using various model and emerging cyanobacterial strains, we have engineered photosynthetic biocatalysts capable of producing amino acids and bioplastic monomers directly from CO₂ and light. Alternatively, as demonstrated using engineered E. coli strains with optimized flux through the reductive TCA cycle, ‘dark’ fermentation processes can also be developed for high-rate fixation of CO₂ as an essential co-substrate. Lastly, in a departure from the conventional focus on using single strains, we have also been investigating the engineering of synthetic co-cultures for developing carbon efficient bioprocesses that further benefit from metabolic ‘division of labor’ and facile tunability. Specifically, by pairing E. coli strains with net CO₂-evolving vs. CO₂-fixing metabolisms, we demonstrate how specific co-product mixtures can be produced from biomass-derived sugars with greater carbon efficiency and less waste.