Modulation of Gut Microbiota, Intestinal Physiology, and Digestive Enzyme Levels by Duo-Strain Probiotics in African Catfish (Clarias gariepinus) Challenged With Aeromonas hydrophila

Abstract

This study aimed to determine the effect of dual-strains probiotic (DSP) consisting of Lactobacillus casei and Bacillus subtilis on bacterial metagenomic profile, gut physiology, and digestive enzyme levels of African catfish (Clarias gariepinus) infected by Aeromonas hydrophila. The ratio between L. casei and B. subtilis was 1:1 each with a density of 108 CFU/mL. Catfish (n = 8 fish per tank, three replicates per treatment) were fed diets supplemented with 0%, 5%, 10%, or 15% DSP for 42 days. On the 35th day, selected groups were intraperitoneally challenged with A. hydrophila at a dose of 0.1 mL × 108 CFU/mL. The observed parameters included bacterial counts and microbial profile in the gastrointestinal tract (analyzed using next-generation sequencing [NGS]), gut physiology, and digestive enzyme levels (amylase, lipase, and protease). The results showed that DSP supplementation increased both the abundance and diversity of gastrointestinal microbes, elevated digestive enzyme levels, and enhanced the number of goblet cells in the intestinal lining. The dominant microbial phyla observed in the control group were Fusobacteria and Pseudomonadota.