Host-triggered prophage induction drives Lactiplantibacillus plantarum symbiosis through bacterial lysis.

The release of bacterial bioactive molecules across the gut barrier is a crucial yet poorly understood step in host-microbe communication. Here, we identify a phage-driven mechanism associated with this process in the beneficial symbiont Lactiplantibacillus plantarum NC8 (LpNC8). We show that a stress-responsive prophage, pp2, undergoes activation and triggers holin-lysin-mediated bacterial lysis, leading to the production of infectious phage particles and increased extracellular recovery of bacterial vesicles carrying lipoteichoic acids. In a model of nutritional symbiosis, pp2-dependent lysis is required for LpNC8 to promote juvenile growth in undernourished Drosophila melanogaster. Disruption of prophage-mediated lysis impairs vesicle recovery and host growth promotion. Furthermore, we demonstrate that the copper cell region of the Drosophila midgut acts as a physiological trigger of prophage induction. Together, our findings link host intestinal physiology to prophage activity and bacterial lysis, revealing phage-driven lysis as a mechanism contributing to beneficial bacterial-host interactions during nutritional stress.