三种不同乳酸菌对凡纳滨对虾生长、抗病力及肠道菌群结构的影响

本研究比较了饲料中添加粪肠球菌(Enterococcus faecalis LYB1)、嗜酸乳杆菌(Lactobacillus acidophilus W2)和凝结芽孢杆菌(Bacillus coagulans NJ17)对凡纳滨对虾(Litopenaeus vannamei)幼虾的生长、抗病力及肠道菌群结构的影响。以基础饲料中分别添加1.0×1010 cfu/kg浓度的3种不同乳酸菌为实验组,以基础饲料为对照组,以投喂方式养殖对虾42 d。养殖结束后,进行14 d的副溶血弧菌(Vibrio parahaemolyticus)攻毒实验。研究表明:投喂3种乳酸菌的实验组对虾的体重、特定生长率、饲料效率和表观消化率均显著高于对照组(P<0.05),其中以添加凝结芽孢杆菌组效果最佳。攻毒实验显示,添加粪肠球菌和嗜酸乳杆菌均可显著降低对虾的累计死亡率(P<0.05)。添加乳酸菌的各实验组对虾的肠道细菌群落结构与对照组相比均发生了明显变化,其中以添加粪肠球菌组差异最大。在门水平上,变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)为对虾肠道优势菌群。在纲分类水平上,α-变形菌纲(Alphaproteobacteria)、丹毒丝菌纲(Erysipelotrichia)和黄杆菌纲(Flavobacteriia)为对虾肠道优势菌群。研究结果显示,凝结芽孢杆菌NJ17对凡纳滨对虾促长效果最佳,而嗜酸乳杆菌W2对对虾抗病力提高效果最佳,3种乳酸菌均明显改善了对虾肠道微生物群落的组成和丰度。

Effects of Different Lactic Acid Bacteria Added to Feed on the Growth Performance,Disease Resistance and Intestinal Microflora of Litopenaeus vannamei

In this study,we compared the effects of adding Enterococcus faecalis LYB1,Lactobacillus acidophilus W2 and Bacillus coagulans NJ17 to feed on the growth,disease resistance and intestinal flora structure of Litopenaeus vannamei larvae.Three kinds of lactic acid bacteria were fed separately with the additive concentration of 1.0×1010 cfu/kg feed,and prawns fed with basic feed were used as the control.The breeding period was 42 days.After the breeding experiment,a 14-day Vibrio parahaemolyticus challenge experiment was conducted.The results showed that the weight,specific growth rate,feed efficiency and apparent digestibility of prawns fed with 3 kinds of lactic acid bacteria were significantly higher than those of the control(P<0.05),and the effect of adding Bacillus coagulans was the best.The toxicity test showed that the addition of E.faecalis and L.acidophilus significantly reduces the cumulative mortality rate of prawns(P<0.05).Compared with the control,the bacterial community structure of prawn intestinal tract in each experimental group added with lactic acid bacteria has obvious changes,and the group added with E.faecalis has the greatest difference.At the phylum level,Proteobacteria,Firmicutes and Bacteroidetes are the dominant microflora in prawn intestinal tract.Compared with the control,the abundance of Proteobacteria in each experimental group increased while that of Firmicutes decreased.At the class level,α-Proteobacteria,Erysipelotrichia and Flavobacteriia are the dominant intestinal flora of prawn.Compared with the control,the abundance ofα-Proteobacteria in E.faecalis group and L.acidophilus group increased while that of erysipelas group decreased.Overall,B.coagulans NJ17 has the best growth promoting effect on L.vannamei while L.acidophilus W2 has the best effect on improving the disease resistance of prawn.All three lactic acid bacteria have significantly changed the composition and abundance of intestinal microbial communities of prawn.