Lumichrome metabolism mediates semiconductor-driven solar energy conversion in non-phototrophic Shewanella

Non-phototrophic microorganism-semiconductor systems have been designed for solar-to-chemical conversion. However, the conversion mechanism remains unclear due to the lack of photosensitive enzymes in non-prototrophic pathways. Herein, the mechanism of non-phototrophic Shewanella woodyi to convert solar energy through CaTiO 3 is investigated by untargeted metabolism. By controlling the amount of CaTiO 3 , the extracellular electron transfer pathway of S. woodyi is upregulated in light. Subsequently, the interfacial electron transfer between CaTiO 3 and S. woodyi regulates microbial activity through tryptophan metabolism. Notably, the transformation of riboflavin to lumichrome under light is the key step that mediates upregulation of indole-3-acetic acid in tryptophan metabolism. As a result, the glycolysis and tricarboxylic acid cycle is promoted, leading to an increase in biomass. This study advances the understanding of energy harvesting mechanisms in non-prototrophic organisms and provides reference for designing effective semiconductor-microbe systems.