Lactiplantibacillus plantarum Ameliorated Growth Performance and Intestinal Inflammation by Modulating Gut Microbial Structure and Function of Yellow River Carp (Cyprinus carpio).

This research was conducted to evaluate the probiotic properties of Lactiplantibacillus plantarum (L. plantarum) P-8 through in vitro experiments and 12-week in vivo feeding trials, investigating its effects on growth performance, intestinal immunity, and microecology in Yellow River carp. In vitro experiments showed that L. plantarum P-8 inhibited various aquatic pathogenic bacteria and exhibited a certain level of safety in drug resistance tests. In the in vivo dosing feeding trial, fish (initial weight: 10.18 ± 0.01 g) were divided into five groups: CF, LP6, LP7, LP8, and Abx/LP8. Compared with CF group, the dietary addition of L. plantarum P-8 (1 × 10⁸ CFU/g) in the LP8 and Abx/LP8 groups enhanced serum immune and antioxidant properties (P < 0.05), stimulated myofiber hyperplasia and hypertrophy through the promotion of muscle development (pax7, myf5, myod, myog, and mrf4) and suppression of muscle atrophy (mstnb) related gene expression (P < 0.05), and optimized the intestinal microbiota structure by increasing the abundance of Lactobacillus and Blautia, decreasing Flavobacterium and Helicobacter (P < 0.05), thereby improving intestinal health and growth performance. However, the LP6 and LP7 groups showed no significant health benefits. The pseudo-germ-free fish model (Abx/LP8 group) further demonstrated that L. plantarum P-8 can significantly modulate the structure and function of intestinal microbiota. Additionally, L. plantarum P-8's efficacy in reducing inflammation and fortifying the intestinal barrier was confirmed in faba bean-induced enteritis model. These evidences suggested that L. plantarum P-8 (1 × 10⁸ CFU/g) improved intestinal health and growth performance by modulating the structure and function of intestinal microbiota.