Correlation of microbiota in the gut of fish species and water

To analyze the intestinal microbiota diversity of several important economic fishes in the Loudi area and its correlation with the microbiota of water environment, the high-throughput sequencing based on the bacteria 16S rRNA was used to analyze the intestinal microbiota diversity in fish intestines and water. The results revealed that half of the OTUs in the water sample could be detected in the fish intestine, the proportion of shared OTUs in the intestines of Hypophthalmichthys molitrix and water samples was only 22%, and the unique OTU in the LC group was relatively the highest in the fish intestinal group. It can be seen from the analysis in NMDS analysis, the distance between Hypophthalmichthys molitrix group and water group is relatively farthest. Ctenopharyngodon idellus has the highest microbiota richness and diversity (P < 0.05), while the water samples have the lowest microbiota richness (P < 0.05). Firmicutes, Methylocaldum and Bacillus are the prevalent taxonomic unit in the Aristichthys nobilis and Carassius auratus groups, Anaerospora is the prevalent genera in the Hypophthalmichthys molitrix group, Proteobacteria and Cyanobacteria have a high relative abundance ratio in the Ctenopharyngodon idellus group, and the prevalent taxonomic unit in the water sample group are Phenylobacterium, Bacteroidetes and Actinobacteria. In conclusion, fish species have different prevalent microbiota. There are a strong correlation between fish intestinal microbiota and the water environment, and the fish with a weak correlation is Hypophthalmichthys molitrix. Results of this study will contribute to the prevention and treatment of fish diseases and the fish ecological culturing in Loudi area.