Dietary supplementation with recombinant shrimp c-type lysozyme modulates the gut microbiome and enhances growth performance and resistance to Ecytonucleospora hepatopenaei infection in Pacific white shrimp (Litopenaeus vannamei)

Abstract

Ecytonucleospora hepatopenaei (EHP) is a microsporidian parasite associated with growth retardation and size variation in shrimp. In recent years, it has emerged as a serious threat to shrimp aquaculture worldwide. A c-type lysozyme (LvLyz-c) from Pacific white shrimp (Litopenaeus vannamei) has been shown to inhibit EHP spore germination and reduce infectivity. This study investigated the protective effects of dietary supplementation with recombinant LvLyz-c (rLvLyz-c) against EHP infection. After a 14-day feeding trial, gut microbiome analysis revealed increased richness, diversity, and abundance of beneficial bacteria in shrimp fed a basal diet supplemented with rLvLyz-c, compared to those fed a basal diet supplemented with either sodium chloride-Tris-EDTA buffer (control) or commercial hen egg-white lysozyme (HEWL). Additionally, shrimp fed rLvLyz-c supplementation exhibited significantly higher weight gain (p < 0.05), and lower, but not significantly different, feed conversion ratios compared to the control and HEWL groups. Upon EHP infection, shrimp fed rLvLyz-c had significantly lower EHP copy numbers (∼10³–10⁴ copies) than those fed basal (∼10⁶ copies) or HEWL (∼10⁶ copies) diets at 12 days post-cohabitation. Supplementation with rLvLyz-c enhanced shrimp health indicators, including total hemocyte counts and intestinal wall thickness. These effects were associated with upregulation of immune-related genes, including LvHSP70, LvHSP90, LvPrx4, LvPEN3, CrustinLv4, and LvLyz-c. Overall, dietary rLvLyz-c supplementation improved gut microbiota composition, growth performance, and immune response in L. vannamei, demonstrating its potential as a feed additive to protect against EHP infection.