Microhybridization enhances intestinal microbiota and glycometabolic regulation in natural gynogenic blunt snout bream derived from the blunt snout bream (Megalobrama amblycephala, ♀) × Chinese perch (Siniperca chuatsi, ♂)

Gut microbiota plays critical roles in host nutrition and metabolism, but research on the intestinal nutrition and gut microbiota of gynogenetic offspring, especially from omnivorous and carnivorous crosses, remains scarce. Intestinal tissues were collected from natural gynogenetic blunt snout bream (GBSB) and its parents ( Megalobrama amblycephala ♀ and Siniperca chuatsi ♂) for metagenomic sequencing, histological examination, enzyme activity assay, and quantitative gene expression quantification. Pearson correlation analysis was also performed to determine the correlations between microbial functional abundance and metabolic gene expression. Our study found that the intestinal of GBSB exhibited higher antioxidant (catalase, reduced glutathione) and digestive enzyme (alkaline xylanase, acid phosphatase, lipase) activities than normal blunt snout bream (BSB). Metabolically, the expression levels of glycolysis-related genes ( GADPH , Idha ) were downregulated in GBSB, whereas those of pentose phosphate pathway genes ( Pgd , Taldo1 ) were upregulated. The gut microbiota in GBSB closely resembled that in the maternal line, sharing Bacillus as a dominant genus, although shifts occurred within the Bacteroidota and Pseudomonadota phyla. Correlation analysis suggested that heterologous sperm induction altered host gene expression, which drove gut microbiota restructuring through host-microbiota interactions in sugar metabolism. In general, microhybridization improved the digestion performance of GBSB, and its glucose metabolism pathways such as glycolysis, pentose phosphate pathway and tricarboxylic acid cycle were regulated to a certain extent compared with the maternal parent. These host metabolism-microbiota dynamics are crucial for optimizing feeding strategies and health management in novel gynogenetic fish breeds.