Optogenetic control of gut bacterial metabolism

Gut bacteria secrete metabolites that impact the host. However, studies of the molecular mechanisms by which the microbiome impacts the host are challenging due to the poor accessibility of the gut environment. Here, we demonstrate that optogenetics can be used to remotely control Escherichia coli gene expression and metabolism in the gastrointestinal tract of live Caenorhabditis elegans worms. Using this approach, we reveal that gut bacterial secretion of the exopolysaccharide colanic acid (CA) protects worm intestinal mitochondria from stress-induced fragmentation. In addition, we show that light-activated CA secretion extends worm lifespan. Optogenetic control of gut bacteria will enable new mechanistic studies of how the microbiome impacts health and disease.