Intestinal bacterial signatures of the "cotton shrimp-like" disease explain the change of growth performance and immune responses in Pacific white shrimp (Litopenaeus vannamei).

Imbalance of intestinal microbiota has been recognized in aquatic animals infected with various diseases. However, the signature of intestinal bacteria of the "cotton shrimp-like" disease in the Pacific white shrimp Litopenaeus vannamei remains unknown. This study investigates the composition, diversity, microbial-mediated function and interspecies interaction of intestinal microbiota on shrimp with different health status using 16S rRNA gene high-throughput sequencing. Meanwhile, the growth performance and the mRNA expression of innate immune gene in hepatopancreas were also investigated. The growth performance and the mRNA expression of innate immune genes (e.g., crustin, toll, and immune deficiency genes) in the hepatopancreas were significantly decreased in diseased shrimp compared with healthy shrimp. Bacteria of the family Rickettsiaceae and genus Tenacibaculum were exclusively enriched and significantly increased in diseased shrimp, respectively, whereas, the Actinobacteria class dramatically deceased. The diseased shrimp exhibited higher ACE and Chao1 indices and lower complexity of intestinal interspecies interaction than healthy shrimp. Microbial-mediated functions predicted by PICRUSt showed that 83% KEGG pathway including nutrient absorption and digestion significantly increased in diseased shrimp. This study provides an overview on the interplay among the "cotton shrimp-like" disease, intestinal microbiota, growth performance and host immune responses from an ecological perspective.