Bacterial peptidoglycan acts as a digestive signal mediating host adaptation to diverse food resources in *C. elegans*

This study investigates the signals activating the host digestive system to consume varied foods, using *C. elegans*. Researchers discovered that bacterial peptidoglycan (PGN) is a unique food signal activating digestion of inedible food. Gut glycosylated protein BCF-1 interacts with PGN, inhibiting the mitochondrial unfolded protein response (UPRmt) via neuropeptide NLP-3. UPRmt hinders digestion, linked to the p38 MAPK/PMK-1 pathway. Inhibiting PMK-1 alleviates digestion defects in *bcf-1* mutants. Digestion defects reduce adaptation capabilities. PGN-BCF-1 interaction promotes digestion and growth, facilitating consumption of a wide range of foods.

Fanrui Hao, Huimin Liu, Bin Qi