Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China.
Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China; School of Biological Sciences, Lake Superior State University, Sault Ste. Marie, MI, 49783, USA.
Fish Shellfish Immunol. 2020 Nov;106:8-20. doi: 10.1016/j.fsi.2020.06.061. Epub 2020 Jul 25.
Functional ingredients such as Bacillus subtilis are used in aquaculture to improve fish condition, modulate microbiota and promote a healthy intestinal system. However, the underlying mechanisms of grass carp treated with B. subtilis are not fully characterized. This study investigated the gut microbes of grass carp after treated with B. subtilis H2 (10 CFU/mL) and Aeromonas hydrophila (10 CFU/mL). The intestinal flora was found that the dominant bacterial phyla identified in all samples were Proteobacteria, Actinobacteria, Fusobacteria, Bacteroidetes and Acidobacteria. Compared with the control group, the relative abundance of Proteobacteria and Bacteroidetes in B. subtilis group were significantly increased. In addition, the relative abundances of Aeromonas and Shewanella in A. hydrophila group were more than the control group. For the intestinal transcriptomic profiling of the grass carp treated with B. subtilis H2, 824 different expressed genes (DEGs) between the B. subtilis H2 treated and non-treated groups were detected, including 365 up-regulated and 459 down-regulated genes. Six DEGs were randomly selected for further validation by quantitative real-time RT-PCR (qRT-PCR) and the results were consistent with the RNA-seq data. Additionally, eight immunomodulatory genes (IL-4, IL-11, IFN-α, CSF, FOSB, MAPK12b, IGHV3-11 and IGHV3-21) were significantly up-regulated after treated with B. subtilis H2. Furthermore, almost all the lipid metabolism-associated genes were significantly up-regulated after treated with B. subtilis H2 according to the lipid metabolism pathways. Eleven lipid metabolism-associated genes were selected by qRT-PCR, which showed that the expressions of almost all the selected genes were increased, especially Apob-48, ABCG8 and DGAT. Taken together, our results support that B. subtilis could modulate the immune response, fat metabolism and bacterial assembly in the gut of grass carp.
功能成分，如枯草芽孢杆菌，用于水产养殖中改善鱼类状况、调节微生物群和促进健康的肠道系统。然而，用枯草芽孢杆菌处理草鱼的潜在机制尚未完全阐明。本研究探讨了用枯草芽孢杆菌 H2（10 CFU/mL）和嗜水气单胞菌（10 CFU/mL）处理后的草鱼肠道微生物。发现所有样品中主要的细菌门是变形菌门、放线菌门、梭杆菌门、拟杆菌门和酸杆菌门。与对照组相比，枯草芽孢杆菌组的变形菌门和拟杆菌门的相对丰度显著增加。此外，嗜水气单胞菌组的气单胞菌属和希瓦氏菌属的相对丰度高于对照组。对于用枯草芽孢杆菌 H2 处理的草鱼的肠道转录组分析，在枯草芽孢杆菌 H2 处理组和未处理组之间检测到 824 个差异表达基因（DEGs），包括 365 个上调基因和 459 个下调基因。随机选择了 6 个 DEGs 进行进一步的定量实时 RT-PCR（qRT-PCR）验证，结果与 RNA-seq 数据一致。此外，用枯草芽孢杆菌 H2 处理后，8 个免疫调节基因（IL-4、IL-11、IFN-α、CSF、FOSB、MAPK12b、IGHV3-11 和 IGHV3-21）显著上调。此外，根据脂质代谢途径，用枯草芽孢杆菌 H2 处理后，几乎所有与脂质代谢相关的基因都显著上调。通过 qRT-PCR 选择了 11 个与脂质代谢相关的基因，结果表明，几乎所有选定基因的表达都增加了，特别是 Apob-48、ABCG8 和 DGAT。总之，我们的研究结果表明，枯草芽孢杆菌可以调节草鱼肠道的免疫反应、脂肪代谢和细菌组成。
