IntroductionScreening excellent bacterial strains for fermentation is the key to improving the nutritional value and bioavailability of soybean meal (SBM). This study investigated the application of Bacillus subtilis-fermented soybean meal (FSBM) on the feed of Pacific white shrimp (Litopenaeus vannamei).MethodsFSBM was used to replace 0%, 25%, 50%, 75%, and 100% fish meal, and the feeding trial was lasted for 8 weeks (initial weight: 0.9 g).Results and discussionThe amino acid profile in the whole shrimp body was tested. FSBM substitution only significantly reduced the content lysine in whole shrimp body, but increased the content of arginine. Fatty acid data showed that the content of n-6 PUFAs in whole shrimp was significantly increased by FSBM substitution. In muscle, FSBM substitution significantly reduced the content of MUFAs, but increased the content of PUFAs including C18:3n-3, C18:2n-6 and C20:4n-6. No hepatopancreas structure modifications appeared in the 25% group compared with the control group. Subsequently, we investigated the response patterns of different organs to FSBM substitution from antioxidant, endoplasmic reticulum stress and immunity. A high proportion of FSBM significantly reduced the content of GSH in hemolymph and hepatopancreas, while increased the mRNA expression of cat. FSBM substitution did not affect the activities of antioxidant enzymes in the intestine. However, the mRNA expression level of hsp70 in the intestine was significantly reduced by FSBM. In terms of immunity, the mRNA expression levels of lgbp and penaeidin in the hepatopancreas showed a significant linear increase trend. In muscle, high proportion of FSBM significantly increased the mRNA expression of imd. FSBM substitution did not significantly affect the expression of immune genes in the intestine. In terms of endoplasmic reticulum stress, FSBM substitution significantly increased the mRNA expression of eif2α in the hepatopancreas. In muscle, FSBM substitution inhibited the mRNA expression of bip. In the intestine, FSBM replacing 75% of fish meal significantly increased the mRNA expression of bip and ire1. In summary, this study indicated that when the fish meal content account for 40% in diets (dry weight), the screened Bacillus subtilis-FSBM can replace 25% of fish meal protein without reducing the antioxidant and immune abilities of shrimp.

中文翻译：

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枯草芽孢杆菌发酵豆粕替代鱼粉对凡纳滨对虾抗氧化活性、免疫、内质网应激和肝胰腺组织学的影响


引言筛选优良发酵菌株是提高豆粕营养价值和生物利用度的关键。本研究探讨了枯草芽孢杆菌发酵豆粕（FSBM）在南美白对虾（Litopenaeus vannamei）饲料中的应用。方法用FSBM替代0%、25%、50%、75%和100%鱼粉，饲养试验持续8周（初始体重：0.9 g）。结果与讨论对虾整体的氨基酸谱进行了测试。 FSBM替代仅显着降低了全虾体内赖氨酸的含量，但增加了精氨酸的含量。脂肪酸数据表明，FSBM 替代后，整虾中 n-6 PUFA 的含量显着增加。在肌肉中，FSBM替代显着降低了MUFA的含量，但增加了PUFA的含量，包括C18:3n-3、C18:2n-6和C20:4n-6。与对照组相比，25%组未出现肝胰腺结构改变。随后，我们从抗氧化、内质网应激和免疫等方面研究了不同器官对 FSBM 替代的反应模式。高比例的FSBM显着降低了血淋巴和肝胰腺中GSH的含量，同时增加了cat的mRNA表达。 FSBM 替代不影响肠道中抗氧化酶的活性。然而，FSBM 显着降低了肠道中 hsp70 的 mRNA 表达水平。免疫方面，肝胰腺中lgbp和penaeidin的mRNA表达水平呈现显着的线性增加趋势。在肌肉中，高比例的 FSBM 显着增加了 imd 的 mRNA 表达。 FSBM 替代并没有显着影响肠道中免疫基因的表达。在内质网应激方面，FSBM替代显着增加了肝胰腺中eif2α的mRNA表达。在肌肉中，FSBM 替代抑制了 bip 的 mRNA 表达。在肠道中，FSBM替代75%的鱼粉显着增加了bip和ire1的mRNA表达。综上所述，本研究表明，当日粮中鱼粉含量占40%（干重）时，筛选的枯草芽孢杆菌-FSBM可替代25%的鱼粉蛋白，且不会降低对虾的抗氧化和免疫能力。