饲料中添加芽孢杆菌组分对凡纳滨对虾幼虾生长、能量代谢和抗WSSV能力的影响

Effects of Different Components of Bacillus sp. on Growth, Energy Metabolism and WSSV Resistance of Litopenaeus vannamei Juveniles

以凡纳滨对虾(Litopnnaus vannamei)幼虾为实验动物,在其基础饲料中分别添加芽孢杆菌(Bacillus sp.)胞外蛋白粗提物(1.0%,胞外蛋白组)、胞内多糖粗提物(1.0%,胞内多糖组),以基础饲料为对照组饲料,进行为期28d的养殖实验,探讨芽孢杆菌胞外蛋白和胞内多糖粗提物对幼虾生长、能量代谢及抗病能力的影响。研究表明,芽孢杆菌2种粗提物对凡纳滨对虾的生长和成活率影响不显著(P>0.05)。饲喂2种粗提物影响了凡纳滨对虾肝胰腺和肌肉中能量代谢相关酶活力。胞外蛋白组肝胰腺中磷酸果糖激酶(PFK)、乳酸脱氢酶(LDH)活力在养殖实验前期显著高于对照组(P<0.05),而肌肉中PFK、LDH活力显著低于对照组(P<0.05);胞内多糖组肝胰腺中己糖激酶(HK)活力及肌肉中PFK、LDH活力显著低于对照组(P<0.05)。饲喂2种粗提物均显著提高了凡纳滨对虾肌肉中琥珀酸脱氢酶(SDH)活力和肝胰腺中电子传递系统(ETS)活力(P<0.05),胞外蛋白粗提物对肝胰腺中的SDH活力也有显著的提高作用(P<0.05)。饲喂2种粗提物显著降低了凡纳滨对虾肝胰腺及肌肉组织中脂肪酸合酶(FAS)含量(P<0.05)。此外,饲喂2种粗提物均会显著提高凡纳滨对虾肠道蛋白酶活力(P<0.05),而胞外蛋白粗提物使凡纳滨对虾肠道脂肪酶活力显著降低(P<0.05)。白斑综合征病毒(WSSV)感染后,与对照组相比,胞外蛋白组和胞内多糖组凡纳滨对虾半致死时间分别延长了26.19%和7.14%。根据以上结果推测,芽苞杆菌2种粗提物能够影响凡纳滨对虾能量代谢水平并提高其抗WSSV能力,且二者之间密切相关。

A 28-day feeding trial followed by a white spot syndrome virus(WSSV) challenge test were performed to investigate the effects of crude extracts of the extracellular proteins and intracellular polysaccharides of Bacillus sp. added to diets on the growth, energy metabolism and WSSV resistance of Litopenaeus vannamei(initial weight,(0.88±0.04) g). The dosage of extracellular proteins and intracellular polysaccharides in the diets was 1%. The results showed that crude extracts of extracellular proteins and intracellular polysaccharides had no significant effect on the growth and survival rate of shrimp(P>0.05). Feeding the two crude extracts affected the enzyme activities participating in energy metabolism in hepatopancreas and muscle of shrimp. The activities of phosphofructokinase(PFK) and lactate dehydrogenase(LDH) in hepatopancreas were significantly higher in the extracellular protein group than those in the control group(P<0.05) while the activities of PFK and LDH in muscle in the extracellular protein group were significantly lower than those in the control group(P<0.05). The activity of hexokinase(HK) in hepatopancreas and the activity of PFK and LDH in muscle were significantly lower in the intracellular polysaccharide group than those in the control group(P<0.05). Feeding the two crude extracts significantly increased the activity of succinate dehydrogenase(SDH) and electron transport system(ETS) in the muscle of shrimp(P<0.05). The extracellular protein crude extracts also significantly increased the SDH activity in the hepatopancreas(P<0.05). Feeding the two crude extracts significantly reduced fatty acid synthase(FAS) content in hepatopancreas and muscle tissue of shrimp(P<0.05). In addition, feeding the two crude extracts significantly increased the intestinal protease activity of shrimp(P<0.05) while the extracellular protein crude extract significantly decreased the intestinal lipase activity(P<0.05). After infection with WSSV, compared with the control group, the half-lethal time(LT50) of shrimp in the extracellular protein group and the intracellular polysaccharide group was prolonged by 26.19% and 7.14%, respectively. Based on the above results, the aerobic metabolism level of carbohydrates was increased while the lipid metabolism level of shrimps was inhibited by the two crude extracts. Consequently, it was inferred that the effects of two crude extracts on WSSV resistance of shrimp were closely related to their impacts on energy metabolism.