Abstract:

This experiment aimed to investigate the effects of a phage cocktail preparation on the intestinal microbiota of Litopenaeus vannamei. Vibrio strains were isolated and identified from canvas-pond aquaculture environments, while the antibacterial efficacy of the phage cocktail against Vibrio was evaluated. Two experimental groups were established, each with three replicate culture tanks. The phage group was fed with a diet containing the phage cocktail preparation, while the control group was fed with a standard diet. Differences in intestinal microbiota were analyzed using 16S rRNA high-throughput sequencing. Three Vibrio strains were isolated from the canvas ponds: DXA (Vibrio owensii), DXD (V. harveyi), and DXF (Vibrio sp. VibC-Oc-076), with the phage cocktail demonstrating effective inhibition against all three strains. Shrimp fed the phage cocktail exhibited significantly increased intestinal microbial richness and more stable bacterial community structures. At the phylum level, Bacteroidota, Proteobacteria, and Verrucomicrobiota dominated both groups, with no significant change observed in Bacteroidota abundance in the phage group. At the genus level, Algoriphagus and Ruegeria abundances initially increased then decreased in the phage group, while Muricauda abundance showed an opposite trend. The Vibrio genus abundance in shrimp intestines remained below 0.3%. Although Vibrio counts decreased on the second day of feeding with the phage cocktail, no significant difference was observed compared to the control group. In conclusion, the Vibrio-targeting phage cocktail enhanced the diversity of intestinal microbiota in L. vannamei and stabilized the gut microecological environment. However, its impact on Vibrio bacteria appeared related to baseline abundance levels, warranting further research to elucidate this correlation.

Key words: Litopenaeus vannamei, Vibrio, phage cocktail, microbiota