摘要： 为研究微滤机过滤对循环水养殖系统水体细菌群落结构的影响，分别在试验第1天、第30天和第60天对无微滤机的池A及微滤机过滤的池B两个养殖红鳍东方鲀(Takifugu rubripes)的循环水养殖系统采集水样，平板计数法测定养殖水体弧菌、细菌总数后，以荧光原位杂交法(FISH)检测养殖水体弧菌属(Vibrio)、红细菌科(Rhodobacteraceae)的空间分布。同时，采用16S rDNA扩增子测序对养殖水体细菌群落组成进行分析。计数结果显示，池A养殖水体弧菌总数均高于池B。除试验第1天外，池A养殖水体异养细菌总数亦均高于池B；FISH检测结果显示，随养殖时间的推移，弧菌数量增长迅速，池A养殖水体中弧菌属聚集成点状，而红细菌科依然较均匀地分布于养殖水体中，池B养殖水体中弧菌属、红细菌科均较均匀地分布于养殖水体中；16S rDNA扩增子测序结果显示，池A和池B养殖水体的细菌组成存在差异，池A养殖水体的弧菌属所占细菌总量的比例均显著高于池B；除试验第30天存在波动外，池A养殖水体的红细菌科所占细菌总量的比例显著低于池B；除试验第1天外，池A与池B养殖水体细菌丰度和多样性均无显著变化。同时初步研究表明系统运行60 d左右，建议对微滤机滤膜进行更换或清洗。本研究初步揭示了微滤机使用与否对循环水养殖系统微生物种群结构的影响，可对循环水养殖系统的病害防控提供理论参考。

关键词: 循环水养殖系统(RAS), 细菌群落结构, 荧光原位杂交(FISH), 16S rDNA扩增子

Abstract: To study the influence of microfiltration on regulating the bacterial c09ommunity structure in recirculating aquaculture systems (RAS), water samples were taken from Takifugu Rubripes farming RAS tank A-with microfiltration and tank B-without microfiltration, respectively on day 1, 30 and 60 of the experiment. The total number of Vibrio spp. and bacteria in the culture water were measured using plate counting method, then the special distribution of Vibrio and Rhodobacteraceae were detected by fluorescence in situ hybridization (FISH). Meanwhile, the bacterial community composition in the water was analyzed by 16S rDNA amplicon sequencing. The counting results showed that the total number of Vibrio in tank B was lower than that in tank A. Except for the first day of the experiment, the total number of bacteria in tank B was lower than that in tank A. The FISH detection showed that with the passage of culture time, the number of detected bacteria increased rapidly; in untreated tank A, Vibrio aggregated as dots, while Rhodobacteraceae were distributed evenly in the water, and in tank B, both Vibrio and Rhodobacteraceae  were distributed evenly in water. The 16S rDNA amplicon sequencing results indicated that there were differences in the bacterial composition and structure between untreated tank A and micro filtered tank B, with the proportion of Vibrio in tank B significantly lower than that in tank A. Except for a few fluctuation on experiment day 30, the proportion of Rhodobacteraceae in  tank B’s water was significantly higher than that in tank A’s. The alpha diversity of microflora in aquaculture water was analysed. Except for experiment on day 1, there was no significant change in bacterial abundance and diversity in the water of tank A and tank B. This paper explores the changes in bacterial populations in RAS water caused by microfiltration, and the related research results are expected to provide a theoretical reference for disease prevention and control in RAS.

Key words: Recirculating Aquaculture System (RAS), bacterial community structure, fluorescence in situ hybridization (FISH), 16S rDNA amplicon sequencing