凡纳滨对虾生物絮团养殖系统中不同生境细菌群落特征

【目的】凡纳滨对虾生物絮团养殖系统(biofloc-based culture system, BFS)是一种基于培育和调控微生物群落的新型生态养殖模式。然而，目前对于BFS在不同生境中的微生物群落特征及其构建过程还不清楚。【方法】采用16S rRNA基因测序技术探究BFS在3种不同生境(水体、絮团和对虾肠道)的细菌群落组成；通过溯源分析和中性模型等方法，探究不同生境细菌群落的特征及其构建过程。【结果】3种生境的微生物群落多样性和组成具有显著性差异，絮团和对虾肠道的群落结构和组成最为相似，溯源结果显示对虾肠道有98.76%的细菌类群来自絮团，仅有0.83%的细菌类群来自水体；3种生境共有的细菌主要为鲁杰氏菌(Ruegeria)，在水体、絮团和对虾肠道中的丰度分别为1.72%、7.34%和6.00%，水体中特有的扩增子变异序列(amplicon sequence variants, ASV)数量为89个，主要属于海茎状菌(Maricaulis)和欧文威克斯菌(Owenweeksia)，絮团中有56个，主要为莱茵海默氏菌(Rheinheimera)，而对虾肠道中仅有10个，主要属于玫瑰杆菌(Roseobacter)；中性模型结果表明，水体、絮团和对虾肠道细菌群落构建均符合中性模型，表明3种生境中细菌群落构建均受中性过程主导。【结论】在BFS系统中，不同生境的微生物群落具有显著差异，对虾肠道细菌主要来自生物絮团，而3种生境的细菌群落构建过程由中性过程主导。这些结果为调控生物絮团养殖系统中微生物群落提供了理论依据。

Characteristics of bacterial communities in different habitats of the biofloc-based culture system of Penaeus vannamei

Objective] The biofloc-based culture system (BFS) of Penaeus vannamei is a new ecological shrimp production mode based on the concept of cultivating and regulating the microbial community in the aquaculture system. However, the characteristics and assembly processes of microbial communities in different habitats of the BFS remain unclear. Methods] The 16S rRNA gene sequencing was employed to explore the bacterial community composition in three different habitats (water, bioflocs, and shrimp gut) of the BFS. SourceTracker and the neutral model were adopted to explore the characteristics and assembly processes of bacterial communities in different habitats. Results] The bacterial community diversity and composition varied significantly in the three habitats, and the structures and composition of bacterial communities were similar between bioflocs and shrimp gut. SourceTracker results showed that 98.76% of bacterial taxa in the shrimp gut were sourced from bioflocs, and only 0.83% were derived from water. Ruegeria existed in all the three habitats, with the relative abundance of 1.72%, 7.34%, and 6.00% in water, bioflocs, and shrimp gut, respectively. The unique amplicon sequence variants (ASVs) showed the maximal number of 89 in water, mainly belonging to Mariculis and Owenweeksia. Bioflocs contained 56 ASVs, which were mainly Rheinheimera. Only 10 ASVs were present in the shrimp gut, mainly belonging to Roseobacter. The bacterial communities in water, bioflocs, and shrimp gut were all fit to the neutral model, which indicated that the bacterial communities in the three habitats were dominated by the neutral process. Conclusion] The microbial communities in different habitats of the BFS were significantly different, and the intestinal bacteria of shrimp mainly came from bioflocs. The assembly processes in the three habitats were dominated by neutral processes. The results provide a theoretical basis for regulating the microbial community in the BFS.