屎肠球菌对凡纳滨对虾生长、非特异免疫及抗病力的影响

Effect of Enterococcus faecium on Growth Performance, Non-Specific Immunity and Disease Resistance of Litopenaeus vannamei

为研究饲料中添加屎肠球菌(Enterococcus faecium,编号HK)对凡纳滨对虾(Litopenaeus vannamei)幼虾的生长、免疫及抗病力的影响,本文在凡纳滨对虾幼虾饲料中,分别添加浓度为1×10^(8)、1×10^(9)、1×10^(10)、1×10^(11)和1×10^(12)cfu/kg的屎肠球菌(分别记为FSA、FSB、FSC、FSD和FSE),以商品饲料作为对照(CON),每个处理组设置5个重复,每个重复15尾虾,实验周期为42 d。研究表明:对虾的成活率为80.0%~92.0%,各组间成活率差异不显著(P>0.05)。FSB和FSC组对虾的末体质量和特定生长率显著高于对照组(P<0.05),FSC组对虾的特定生长率显著高于其他组。FSC和FSD组对虾的血清中碱性磷酸酶(AKP)、酸性磷酸酶(ACP)、超氧化物歧化酶(SOD)、酚氧化酶(PO)、总一氧化氮合酶(T-NOS)活性和溶菌酶(LZM)浓度显著高于对照组(P<0.05)。FSC、FSD和FSE组对虾的肝胰腺中SOD、LZM、proPO、LGBP和HSP70基因表达水平显著高于对照组,FSA、FSB、FSC和FSD组对虾的肝胰腺中Imd、Toll和Relish基因的相对表达量显著高于对照组(P<0.05)。在mTOR信号通路中,FSB、FSC和FSD组对虾肝胰脏中TOR、4E-BP、elF4E1α、elF4E2基因表达水平显著高于对照组(P<0.05)。副溶血弧菌(Vibrio parahaemolyticus)攻毒实验结果表明,FSC组对虾的累计死亡率显著低于对照组和FSA组(P<0.05)。研究结果表明,饲料中添加适宜浓度的屎肠球菌可显著提高凡纳滨对虾的生长性能、免疫能力和抗病力。综合各项指标,饲料中屎肠球菌的最适添加浓度为1×10^(10)cfu/kg。

This experiment was conducted to investigate the effect of Enterococcus faecium on the growth performance, immunity and disease resistance of Litopenaeus vannamei. Five concentrations, 1×10^(8) cfu/kg, 1×10^(9) cfu/kg, 1×10^(10)cfu/kg, 1×10^(11)cfu/kg and 1×10^(12)cfu/kg, were formulated into five experimental diets, FSA, FSB, FSC, FSD and FSE. The control was the basic diet without probiotics. The experiment was carried out for 42 days. The results revealed that the survival rate of shrimp ranged from 80% to 92%, and there was no significant difference among all groups(P>0.05). Comparison of growth of shrimp with different treatments, the specific growth rate and weight gain of shrimp in the FSB and FSC groups were significantly higher than those in the control(P<0.05), and the specific growth rate of shrimp in the FSC group was significantly higher than other treatments. Compared to the control group, the activities of alkaline phosphatase(AKP), acid phosphatase(ACP), superoxide dismutase(SOD), phenol oxidase(PO) and total nitric oxide synthase(T-NOS) and lysozyme(LZM) content were significantly increased in the FSC and FSD groups. The expression levels of SOD, LZM, proPO, LGBP and HSP70 in FSC, FSD and FSE groups were significantly higher than those in the control. The expression levels of Imd, Toll and Relish in FSA, FSB, FSC and FSD groups were significantly higher than those in the control(P<0.05). In the mTOR signaling pathway, the expression levels of TOR, 4E-BP, elF4E1α and elF4E2 in FSB, FSC and FSD groups were significantly higher than those in the control(P<0.05). The challenge test of Vibrio parahaemolyticus revealed that the cumulative mortalities of shrimp in FSC group was significantly lower than that in the control and FSA(P<0.05). In conclusion, dietary supplementation with 1×10^(10)cfu/kg E. faecium HK significantly improved the growth, immunity and disease resistance of L. vannamei.