The cost of bacterial predation via type VI secretion system leads to predator extinction under environmental stress

As a common gut pathogen, Campylobacter jejuni (C. jejuni) harbors the Type VI Secretion System (T6SS) that injects toxic effectors into neighboring cells, modulating microbial competitions in the harsh gut environment. Using bile salt as a natural stressor and T6SS-positive C. jejuni as a predator, we show that T6SS activity could entail a cost during bacterial predation under environmental stress. Our data suggest bile salt influx and subsequent DNA damage due to the prey-driven activation of the T6SS. We further combined experiments and mathematical modeling to explore how the stress-induced predation cost determines ecological outcomes. Consistent with a population-dynamics model, we found predator extinction above a critical bile salt concentration and prey-predator coexistence below this level. Moreover, we utilized the predation cost as an effective strategy facilitating host defense against C. jejuni infection. Together, we elucidate how predator dominance versus extinction emerges from the interplay between environmental stress and the T6SS machinery.

Automated summary

The research reveals that under environmental stress, predation behavior of Campylobacter jejuni may incur a cost involving the activity of the Type VI Secretion System (T6SS), including influx of bile salt and DNA damage. Through experiments and mathematical modeling, the study determines how stress-induced predation cost affects ecological outcomes, finding predator extinction above a critical bile salt concentration and coexistence below this level. The predation cost is also identified as an effective strategy for host defense against C. jejuni infection.