不同密度生态基系统内细菌群落组成与草鱼生长的关系

为了研究生态基系统中细菌群落组成与草鱼生长的关系，实验按生态基表面积占养殖水体表面积的比值50%、100%、150% (S-50、S-100、S-150)，设置3个不同密度的生态基养殖系统。首先测量处理组和对照组的草鱼生长性状，进而利用高通量测序技术分析水体中和生态基上的细菌群落组成，探索生态基系统内细菌群落与草鱼生长的关系。结果显示，S-100和 S-150组的草鱼增重率与特定生长率均显著高于S-50和对照组；S-100组的存活率显著高于其他组；S-100和S-150组的饲料转换率均显著低于对照组。细菌群落分析发现：①与水体相比，生态基上γ-变形菌纲(Gammaproteobacteria)比例增加，且该菌在S-100组中显著高于其他组；②水体中细菌主要以黄杆菌属(Flavobacterium)、红细菌属(Rhodobacte)、鲸杆菌属(Cetobacterium)和浮霉状菌属(Planctomyces)为主，生态基上不动杆菌属(Acinetobacter)、假单胞菌属(Pseudomonas)和金黄杆菌属(Chryseobacterium)占较高比例，并且后3种细菌在S-100组中比例显著高于其他组；③在可鉴定的种水平上，生态基上的细菌主要以产碱假单胞菌(P. alcaligene)和蜡样芽胞杆菌(Bacillus cereu)为主，其中产碱假单胞菌在S-100和S-150组最高。综合草鱼生长性状、细菌群落组成及生态基生产成本分析发现，生态基比表面积为100%时效果最佳，即细菌多样性和潜在益生菌比例高，饵料系数最低，草鱼的存活率和增重率最高。

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.