The purpose of this study was to profile the mechanisms of action of probiotic, Bacillus subtilis E20 in activating the immunity of white shrimp, Litopenaeus vannamei. Two groups of shrimp were studied. One group was fed a control diet without probiotic supplementation and the other was fed a probiotic-containing diet at a level of 109 cfu kg diet-1. After the 8-week feeding regimen, the metabolite composition in the hepatopancreas of shrimp were investigated using 1H nuclear magnetic resonance (1H NMR) based metabolomic analysis. Results from the 1H NMR analysis revealed that 16 hepatopancreatic metabolites were matched and identified among groups, of which 2 metabolites, creatinine and glutamine were significantly higher in probiotic group than in the control group. This result was confirmed by the reverse-phase high-performance liquid chromatography (RP-HPLC) and spectrophotometric analysis. Transcriptome analysis indicated the expressions of 10 genes associated with antioxidant enzymes, pattern recognition proteins and antimicrobial molecules, more active expression in the shrimp fed a diet supplemented with probiotic as compared to that of shrimp in control. In addition, the expressions of 4 genes involved with hexosamine biosynthesis pathway (HBP) and UDP-N-acetylglucosamine-peptide N-acetylglucosaminyltransferase for protein O-glycosylation were also higher in hepatopancreas of probiotic-treated shrimp than in shrimp fed a control diet. Western blot and enzyme-linked immunosorbent assay showed that heat shock factor 1, heat shock protein 70, and protein O-glycosylation in hepatopancreas were higher in probiotic group than the control group. These findings suggest that probiotic, B. subtilis E20 promotes the digestibility of glutamine in the diet, and that the increased glutamine in shrimp can be used as fuel for immune cells or may be used to regulate immune molecule expressions and protein O-glycosylation via the HBP to increase protein O-glycosylation, thereby improving the health of shrimp.

中文翻译：

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益生菌枯草芽孢杆菌E20通过谷氨酰胺代谢和己糖胺生物合成途径改变了白虾，凡纳滨对虾的免疫力。

这项研究的目的是概述益生菌枯草芽孢杆菌E20激活白虾对虾凡纳滨对虾免疫力的作用机制。研究了两组虾。一组饲喂不含益生菌的对照饮食，另一组饲喂含109 cfu kg饮食-1水平的含益生菌的饮食。在喂食8周后，使用基于1H核磁共振（1H NMR）的代谢组学分析研究了虾肝胰腺中的代谢物组成。1 H NMR分析的结果表明，各组之间有16种肝胰腺代谢物被匹配和鉴定，其中益生菌组中的2种代谢物肌酐和谷氨酰胺明显高于对照组。反相高效液相色谱（RP-HPLC）和分光光度法分析证实了该结果。转录组分析显示与抗氧化剂，模式识别蛋白和抗菌素分子相关的10个基因的表达，与对照虾相比，补充了益生菌的虾在饲料中的活性更高。此外，益生菌处理过的虾的肝胰腺中，与六胺生物合成途径（HBP）和UDP-N-乙酰氨基葡萄糖-肽N-乙酰氨基葡萄糖氨基转移酶有关的4个基因的表达也高于对照饮食喂养的虾的肝胰腺。Western blot和酶联免疫吸附试验表明，热休克因子1，热休克蛋白70，益生菌组肝胰腺中蛋白质O-糖基化水平高于对照组。这些发现表明，益生菌枯草芽孢杆菌E20可以提高日粮中谷氨酰胺的消化率，而虾中增加的谷氨酰胺可以用作免疫细胞的燃料，也可以用于调节免疫分子的表达和蛋白质O-糖基化。 HBP增加蛋白质O-糖基化，从而改善虾的健康。