Impact of dietary protein and lipid levels and growth rates on the intestinal microbiota of kuruma shrimp (Penaeus japonicus)

Gut microbiota is essential for host development and growth, with strong links to diet and growth performance in aquatic species. This study explores the bacterial communities in kuruma shrimp (Penaeus japonicus) under different diets and growth rates. Shrimp with an average initial weight of 0.30 ± 0.08 g were fed diets with varying protein (50%, 48%, and 46%) and lipid (11% and 7% in a 3 × 2 experimental design) for 7 weeks. Shrimp fed a 50% protein and 11% lipid diet exhibited superior growth performance (P < 0.05). At the phylum level, Proteobacteria, Bacteroidota, Firmicutes, and Actinobacteriota were predominant, with the Firmicutes/Bacteroidota ratio increasing in response to dietary protein and lipid levels—a trend also observed in fast-growing shrimp. At the genus level, Vibrio, Ralstonia, Shimia, and Spongiimonas were prevalent, with Shimia identified as a biomarker in shrimp fed a high-lipid diet or those exhibiting rapid growth under identical conditions. Whether in different dietary groups or under the same condition, fast-growing shrimp displayed a more intricate bacterial network, with greater connectivity and a higher diversity of keystone taxa compared to slow-growing shrimp. The intestinal metabolism in groups fed diets with high protein and lipid levels was more active than in those receiving lower levels. Collectively, these results indicate the gut microbiota structure of shrimp with different growth performances shows different characteristics, and dietary adjustments can be used to modulate the gut microbiota structure of P. japonicus, promoting optimal growth performance. The diet containing 50% protein and 11% lipid could be considered optimal for its growth and gut health.