Dual roles of the sacrificial agent in efficient solar-to-chemical production by nonphotosynthetic Moorella thermoacetica

The integration of microorganisms and photosensitizers presents a promising approach to chemical production utilizing solar energy. However, the current system construction process remains complex. Herein, we introduce a straightforward and efficient solar-to-chemical conversion system that combines the dissolved photosensitizer Eosin Y with the non-photosynthetic bacterium Moorella thermoacetica . Under light radiation, acetate production increased to 5.1 µM h −1 µM −1 catalyst, exceeding the previously reported maximum by 5.9-fold, with a quantum efficiency of 17.6%. The soluble photosensitizer EY can penetrate the cell and directly engage in intracellular energy metabolism, significantly enhancing intracellular ATP and NADPH/NADP + levels. Within this biohybrid system, sacrificial agent triethanolamine played a dual role: (1) providing continuous photoelectron generation by Eosin Y, enhancing intracellular reducing power, and facilitating carbon fixation via the Wood-Ljungdahl pathway; and (2) its oxidation product, formaldehyde, served as a critical intermediate and a direct precursor for methylenete-trahydrofolate in the Wood-Ljungdahl pathway, consequently simplifying reaction steps and markedly boosting acetate yield. This study provides a simple microorganism-photosensitizer biohybrid system to produce acetate and light on the multifaceted roles of sacrificial agents, paving the development of efficient solar energy conversion with nonphotosynthetic bacteria.