Relationship between bacterial community composition and Ctenopharyngodon idella growth in periphyton substrate systems with different densities

In order to study the relationship between bacterial community composition and Ctenopharyngodon idella growth in the periphyton substrate systems, the ratios of substrate surface area to pool water surface area were set at 50%, 100% and 150% (S-50, S-100 and S-150). Firstly, the growth traits of C. idella in three systems and control groups were measured, and then the high-throughput sequencing technology was used to analyze the bacterial community composition in the water and the substrates, finally, the relationship between bacterial community and C. idella growth in the culture system was explored. The results showed that the weight gain rate and specific growth rate of C. idella in S-100 and S-150 groups were significantly higher than those in S-50 and control group. The survival rate of S-100 group was significantly higher than other groups. The feed conversion rates of the S-100 and S-150 groups were significantly lower than the control group. Bacterial community analysis demonstrated that 1) the proportion of Gammaproteobacteria increased in the substrates compared with the water, and the bacteria was significantly higher in the S-100 group than the other groups; 2) the bacteria in the water mainly consist of Flavobacterium, Rhodobacte, Cetobacterium and Planctomyces, and in the substrates Acinetobacter, Pseudomona and Chryseobacterium accounted for a high proportion, and the latter three bacteria were significantly higher in the S-100 group than those in the other groups; 3) at the identifiable species level, Pseudomonas alcaligene and Bacillus cereu were mainly in the substrates, and Pseudomonas faecalis was the highest in the S-100 and S-150 groups. Comprehensive analysis of C. idella growth, bacterial community composition and substrate cost, showed that the best effect was the 100% substrate group, in which there were the high bacterial diversity and potential probiotics ratio, the minimum feed coefficient and the highest of C. idella survival rate and weight gain rate. These data from this study provided the scientific data for the practical application of substrates in the aquaculture.