Bioconversion of CO2 into valuable bioproducts via synthetic modular co-culture of engineered Chlamydomonas reinhardtii and Escherichia coli
Nam Kyu Kang, Hyun Gi Koh, Yujung Choi, Hyunjun Min, Donald R. Ort, Yong-Su Jin
Abstract
With increasing concern over environmental problems and energy crises, interest in the biological conversion of CO 2 into bioproducts is growing. Although microalgae efficiently utilize CO 2 , their metabolic engineering remains challenging. In contrast, while synthetic biology tools are advanced for many heterotrophic bacteria, these organisms cannot directly utilize CO 2 . As such, a modular co-culture system with a glycolate dehydrogenase 1 (GYD1) deficient C hlamydomonas reinhardtii mutant and Escherichia coli was developed. The GYD1 mutant secretes glycolic acid via photorespiration, which E. coli metabolizes via the glyoxylate cycle. E. coli growth was improved by implementing two-stage continuous systems to 2.0 mg L -1 h -1 on CO 2 . The production of green fluorescent protein (0.52 ng L -1 h -1 ) and lycopene (6.3 μg L -1 h -1 ) was also demonstrated. This study represents a successful case of a synthetic modular co-culture with a microalga and a heterotrophic bacterium, potentially contributing to sustainable industrial processes and reducing environmental impact. • A synthetic modular co-culture was established using microalgae and bacteria. • In the CO 2 fixation module, C. reinhardtii converts CO 2 into glycolic acid. • In the production module, E. coli converts glycolic acid into bioproducts. • GFP and lycopene were produced from CO 2 via the synthetic modular co-culture.