Supplementation with natural prebiotic extracts modulates the intestinal bacterial community of whiteleg shrimp ( <i>Litopenaeus vannamei</i> )

The objective of this study is to screen extracts derived from natural products as potential prebiotics and to evaluate their combine effects with probiotic bacteria, known as synbiotic, on modulating the intestinal microbiota of the whiteleg shrimp, L. vannamei . Experiment 1 evaluated the prebiotic activity index of selected natural extracts based on their capacity to selectively stimulate the growth and metabolic activity of beneficial probiotic bacteria under in vitro conditions. The results show that banana extract showed the highest prebiotic scores for Lactobacillus plantarum LAB8.1CM. In a 30-day feeding trial (experiment 2), shrimp were fed either a control diet or a synbiotic diet containing 0.2% banana extract and 10⁸ CFU/kg L. plantarum. The result showed that 8 phyla, 11 classes, 29 orders, 37 families, and 63 genera were identified and successfully assigned taxonomic classifications. Proteobacteria was the dominant phylum in both treatments, although its relative abundance was reduced in synbiotic-fed shrimp. 16S rRNA gene sequencing revealed that synbiotic supplementation significantly altered gut microbial structure, as indicated by distinct PCA clustering. The synbiotic diet increased microbial richness, Shannon index, and evenness, and enhanced the relative abundance of beneficial taxa such as Firmicutes phylum and Lactobacillus genus. Greater microbial stability was observed in synbiotic-fed shrimp, as indicated by higher Bray–Curtis similarity indices. These results demonstrated that banana-derived prebiotic combined with L. plantarum effectively modulates intestinal microbiota composition and diversity in L. vannamei . The findings support the application of natural synbiotics as sustainable functional feed additives to promote gut health and improve microbial stability in shrimp aquaculture.