AUTHOR=Jiang Yan , Wang Jun , Lin Lin , Xu Yongjiang , Cui Aijun , Wang Kaijie , Liu Xuezhou , Wang Bin 

TITLE=Responses of the gastrointestinal microbiota to the protein metabolism of pond-cultured Japanese flounder (Paralichthys olivaceus)

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2023.1033094

DOI=10.3389/fmars.2023.1033094

ISSN=2296-7745

ABSTRACT=Protein metabolism can provide energy for various biological activities of organisms. However, there have been few studies on the succession of gastrointestinal microbiota structure during protein metabolism of host. In this study, physiological and biochemical, qRT-PCR, and 16S rDNA high throughput sequencing methods were used to detected the activity characteristics of proteases and the related gene expression levels in each gastrointestinal tissue, and distribution characteristics and succession of the gastrointestinal microbiota structure of pond-cultured Japanese flounder (Paralichthys olivaceus). Results showed that activities of pepsin, trypsin, and chymotrypsin in the pyloric caecum and gut, and relative expression levels of the related genes increased first and then decreased, but the ASP and ALA activities showed the opposite tendency. These reflected that the nutrient composition of gastrointestinal tract contents was dynamic, which caused obvious changes to the alpha diversity and structure of gastrointestinal microbiota. Lactobacillus, Acinetobacter, Bacteroides, Escherichia-Shigella, Prevotella, the genera represented by Lachnospiraceae_NK4A136_group and MND1, Sphingomonas, Alistipes, Alloprevotella, Enterobacter, Helicobacter, Myroides, Ruminiclostridium, and Romboutsia were the main gastrointestinal microbiota basing on the dominance, commonality and colonization. Relative abundances of Lactobacillus and Acinetobacter in three gastrointestinal tissues increased first and then decreased. According to the number of shared and dominant genera, the consistency of succession of some genera and increase in the similarity of microbiota structure among three tissues, we inferred that the microbiota was affected by the gastrointestinal tract nutrient composition. Gastrointestinal microbiota genes were mainly enriched in metabolism pathway according to KEGG pathway, and the ratio of Frimicutes to Bacteroidetes, the representative of energy accumulation, performed first increasing and then decreasing trend in each tissue. It was reflected that the main gastrointestinal microbiota played the synergistic effect in the energy accumulation of host. This study will provide a reference for the development of high-efficiency compound feed formulae and improving feed efficiency by regulating the gastrointestinal tract microecology for pond-cultured Japanese flounder.