National Center for Genetic Engineering and Biotechnology (BIOTEC), Phahonyothin Rd., Pathumthani, 12120, Thailand.
Department of Biomedical Informatics, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA.
Fish Shellfish Immunol. 2020 Nov;106:733-741. doi: 10.1016/j.fsi.2020.08.042. Epub 2020 Aug 26.
Biofloc systems generate and accumulate microbial aggregates known as bioflocs. The presence of bioflocs has been shown to change gut bacterial diversity and stimulate innate immunity in shrimp. The microbial niche of bioflocs may therefore have the potential to drive shifts in the shrimp gut microbiota associated with stimulation of innate immunity. We performed shotgun metagenomic analysis and 16S rRNA-based amplicon sequencing to characterize complex bacterial members in bioflocs and the shrimp digestive tract, respectively. Moreover, we determined whether biofloc-grown shrimp with discrete gut microbiomes had an elevation in local immune-related gene expression and systemic immune activities. Our findings demonstrated that the bacterial community in bioflocs changed dynamically during Pacific white shrimp cultivation. Metagenomic analysis revealed that Vibrio comprised 90% of the biofloc population, while Pseualteromonas, Photobacterium, Shewanella, Alteromonas, Bacillus, Lactobacillus, Acinetobacter, Clostridium, Marinifilum, and Pseudomonas were also detected. In the digestive tract, biofloc-grown shrimp maintained the presence of commensal bacteria including Vibrio, Photobacterium, Shewanella, Granulosicoccus, and Ruegeria similar to control shrimp. However, Vibrio and Photobacterium were significantly enriched and declined, respectively, in biofloc-grown shrimp. The presence of bioflocs upregulated immune-related genes encoding serine proteinase and prophenoloxidase in digestive organs which are routinely exposed to gut microbiota. Biofloc-grown shrimp also demonstrated a significant increase in systemic immune status. As a result, the survival rate of biofloc-grown shrimp was substantially higher than that of the control shrimp. Our findings suggested that the high relative abundance of vibrios in bioflocs enriched the number of vibrios in the digestive tract of biofloc-grown shrimp. This shift in gut microbiota composition may be partially responsible for local upregulation of immune-related gene expression in digestive organs and systemic promotion of immune status in circulating hemolymph.
生物絮团系统会产生和积累微生物聚集体，即生物絮团。研究表明，生物絮团的存在会改变虾的肠道细菌多样性并刺激其先天免疫。因此，生物絮团的微生物生态位有可能导致与先天免疫刺激相关的虾肠道微生物群发生变化。我们分别进行了宏基因组和 16S rRNA 扩增子测序，以分别对生物絮团和虾消化道中的复杂细菌组成进行了特征分析。此外，我们还确定了具有离散肠道微生物组的生物絮团养殖虾的局部免疫相关基因表达和全身免疫活性是否升高。我们的研究结果表明，在太平洋白对虾养殖过程中，生物絮团中的细菌群落会发生动态变化。宏基因组分析显示，弧菌占生物絮团种群的 90%，而假交替单胞菌、发光杆菌、希瓦氏菌、交替单胞菌、芽孢杆菌、乳杆菌、不动杆菌、梭菌、海洋杆菌、海洋filum 和假单胞菌也被检测到。在消化道中，与对照组虾相似，生物絮团养殖的虾维持了共生菌的存在，包括弧菌、发光杆菌、希瓦氏菌、颗粒球菌和雷氏菌。然而，生物絮团养殖的虾中弧菌和发光杆菌的丰度分别显著增加和减少。生物絮团的存在上调了肠道器官中编码丝氨酸蛋白酶和酚氧化酶原的免疫相关基因的表达，这些基因通常会暴露于肠道微生物群中。生物絮团养殖的虾的全身免疫状态也显著增加。因此，生物絮团养殖的虾的存活率明显高于对照组虾。我们的研究结果表明，生物絮团中弧菌的相对丰度较高，使生物絮团养殖的虾的消化道中弧菌的数量增加。这种肠道微生物群落组成的变化可能部分解释了肠道器官中免疫相关基因表达的局部上调以及循环血淋巴中全身免疫状态的促进。
