Triploidization modulates intestinal microbiota and promotes growth in Carassius auratus.

Intestinal microbiota plays a key role in modulating host growth. However, the effect of triploidization on intestinal microflora and fast growth has not been fully explored. Here, autotriploid Carassius auratus (3nRR, 3n = 150) derived from Carassius auratus red var. (♀, RCC, 2n = 100) × autotetraploid fish (♂, 4nRR, 4n = 200) was established. Intestinal microbial community analysis of RCC and 3nRR was performed by 16S rRNA gene sequencing. Gut characteristics, growth rate, and digestive enzyme activity of the two groups of fish were explored. Significant changes in gut assemblages were observed in 3nRR fish. Differences in intestinal characteristics (structure, relative gut density, relative gut length, relative gut mass, and Zihler's index) were observed between RCC and 3nRR groups. Associations between microbial assemblages and intestinal characteristics were evaluated. Growth rate and activities of intestinal digestive enzymes (cellulase, amylase and trypsin) were higher in 3nRR compared with that in RCC. Spearman's correlation analysis showed a positive correlation between bacteria orders (Clostridiales, Micrococcales and Lactobacillales) and fast growth in 3nRR. In summary, the findings indicated that triploidization caused changes in gut microbiota and characteristics, and digestive enzyme activity. The relative abundance of several bacteria species was positively correlated with fast growth in 3nRR. The present study provided new insights into the growth mechanism of 3nRR and its interaction with intestinal microorganisms. • Triploidization could alter intestinal flora and gut characteristics in autotriploid Carassius auratus. • Growth rate and activities of intestinal digestive enzymes (cellulase, amylase and trypsin) were higher in autotriploid Carassius auratus compared with that in Carassius auratus red var.. • Spearman's correlation analysis showed a positive correlation between bacteria orders (Clostridiales, Micrococcales and Lactobacillales) and fast growth in autotriploid Carassius auratus. [ABSTRACT FROM AUTHOR]