Specific gut bacterial taxa inhabited in healthy shrimp (Penaeus vannamei) confer protection against Vibrio parahaemolyticus challenge

Host gut bacterial community has strong resistance to the invasion of pathogens. However, the specific gut taxa that could confer the resistance against pathogens in shrimp are largely unknown. Here, we demonstrated that the shrimp in the same tank showed different resistance after pathogenic Vibrio parahaemolyticus challenge. Subsequently, the gut bacterial communities of healthy, diseased, and moribund shrimp were analyzed. The results indicated that the gut bacterial community in the healthy shrimp still kept a high stability after challenge, while they were gradually disordered with the severity of disease in the diseased, and moribund shrimp. Certain specific taxa belonging to Rhodobacteraceae (e.g., Ruegeria, Paracoccus, Sulfitobacter, and Phaeobacter), Fla-vobacteriaceae (e.g., Tenacibaculum) and Demequinaceae (e.g., Demequina) were mainly depleted in the mori -bund shrimp, compared to that in healthy, and diseased shrimp. Seven corresponding strains of above specific taxa including five Rhodobacteraceae, one Tenacibaculum and one Demequina were isolated from the shrimp gut. Then, four different synthetic communities (SynComs) were constructed by using these isolates: SynComA, all five strains from Rhodobacteraceae; SynComB, SynComA + T. lutimaris HBG23; SynComC, SynComA + D. globuliformis TCG4; and SynComD, SynComA + T. lutimaris HBG23 + D. globuliformis TCG4. The addition of these SynComs could not only improve the fitness of shrimp, but also protect them against subsequent V. parahaemolyticus challenge, especially the addition of SynComD. Our study revealed that specific gut bacteria inhabited in healthy shrimp could improve shrimp resistance against pathogenic microbes.