坚忍肠球菌6-24和枯草芽孢杆菌B9对罗氏沼虾免疫水平与肠道环境的改善作用

Improving the Immunity and Intestinal Tract of Macrobrachium rosenbergii by Enterococcus durans 6-24 and Bacillus subtilis B9

摘要:

本研究通过抑菌试验、粘附性实验和特定水解酶活测定，结合16S rDNA和生理生化鉴定，从虾肠道中分离出坚忍肠球菌（Enterococcus durans）6-24和枯草芽孢杆菌（Bacillus subtilis）B9，并初步研究他们在饲喂罗氏沼虾（Macrobrachium rosenbergii）的益生作用。两株菌按1×107 cfu/kg添加到饲料并进行为期4周的投喂实验后，本研究测定了罗氏沼虾的总血球细胞，酚氧化酶原系统（proPO）,抗氧化系统以及溶菌酶变化情况。研究结果显示，罗氏沼虾投喂含有6-24和B9的饲料后，血淋巴中总血球细胞计数（total haemocyte count）显著提高（p<0.05），酚氧化酶（phenol oxidase）、超氧化物歧化酶（superoxide dismutase）以及溶菌酶（lysozyme）的活性同时也有所提高（p<0.05），其中酚氧化酶上升48.24%，溶菌酶上升198.00%。罗氏沼虾肠道消化酶的影响实验显示，添加混合益生菌的实验组虾肠道消化酶（淀粉酶、蛋白酶、脂肪酶）的活性与对照组相比有显著提高（p<0.05），其中蛋白酶活力更是上升84.80%。最后，研究还发现，饲喂坚忍肠球菌6-24和枯草芽孢杆菌B9后，罗氏沼虾肠道中可培养弧菌数量下降59.76%（p<0.05）。研究结果表明，坚忍肠球菌6-24与枯草芽孢杆菌B9能在一定程度上改善罗氏沼虾的肠道环境和免疫水平，具有虾饲用益生菌开发的潜力。

Abstract:

Enterococcus durans 6-24 and Bacillus subtilis B9 were isolated from the intestine of shrimp through antibacterial tests, adhesion tests and specific hydrolase activity determinations, in combination with 16S rDNA and physiological and biochemical identification. A preliminary study was carried out on the probiotic effects of 6-24 and B9 in feeding Macrobrachium rosenbergii. After the two strains were added to the feed at 1×107 cfu/kg, a 4-weekfeeding experiment started, and the changes in total blood cells, prophenoloxidase system (proPO), antioxidant system and lysozyme of M. rosenbergii were determined. The research results showed that after M. Rosenbergii was fed with the feed containing 6-24 and B9, the total hymphocyte count increased significantly (p<0.05), with the activities of phenoloxidase, superoxide dismutase and lysozyme increased simultaneously (phenol oxidase increased by 48.24%; lysozyme increased by 198.00%). The experiments on the intestinal digestive enzymes of Macrobrachium rosenbergii revealed that compared to the control, the activities of digestive enzymes (amylase, protease, lipase) of the experimental group fed with mixed probiotics increased significantly (p<0.05) (among which, the protease increased by 84.80%). Finally, the research revealed that the number of cultivable Vibrio in the intestine of Macrobrachium rosenbergii fedwith6-24 and B9 decreased by 59.76% (p<0.05). The results showed that Enterococcus durans 6-24 and Bacillus subtilis B9 can improve the intestine environment and immunity level of M. rosenbergii, and have the potential to become probiotic shrimp feed additives.