饲料中补充蜡样芽孢杆菌对凡纳滨对虾生长及其肠道微生物组成的影响

为了研究外源补充蜡样芽孢杆菌对凡纳滨对虾生长及对其肠道微生物组成的影响,以基础饲料为空白组,在基础饲料中添加蜡样芽孢杆菌活菌作为实验组(活菌含量为108 CFU/g),每组4个平行,在养殖场对凡纳滨对虾自幼苗至成虾进行一个完整养殖周期的养殖实验。选取养殖场中8个光照、位置等条件基本相同的养殖池分为2组,空白组投喂基础饲料,实验组投喂免疫饲料,养殖周期95 d。期间在第45、52、59、66、73天采样,称重并计算生长速率,并取其肠道内容物提取DNA,用16S r DNA序列V4区高通量测序方法检测对虾肠道内微生物群落的结构及变化情况。结果显示:(1)投喂免疫饲料的实验组对虾生长速度比空白组平均快15.2%。(2)健康的凡纳滨对虾肠道微生物以变形菌门和拟杆菌门含量高,厚壁菌门、疣微菌门、浮霉菌门、放线菌门含量较低。(3)空白组变形菌门平均含量(68.30%),明显高于实验组平均含量(57.94%);空白组拟杆菌门平均含量(23.58%)明显低于实验组平均含量(30.06%)。(4)变形菌门中以弧菌属、Anaerospora、小红卵菌属为主,空白组弧菌属平均占总含量的5.40%,实验组平均占总含量的1.94%;拟杆菌门中以异养硝化菌属、粘着杆菌属为主,实验组异养硝化菌属平均占总含量的8.12%,空白组平均占含量的5.56%。研究表明,饲料中添加蜡样芽胞杆菌投喂凡纳滨对虾后可改变对虾肠道的微生物组成,提高对虾生长速度。

Effects of dietary with Bacillus cereus on the growth rate and intestinal microflora of Litopenaeus vannamei

In order to research the effect of Bacillus cereus on the growth rate and intestinal microflora of Litopenaeus vannamei, Bacillus cereus (number PC465) was added to basic feed with concentration of viable bacteria of 10⁸ CFU/g. Shrimps living in 8 pools with the similar light and position were divided into two groups, and the experimental group was fed the immune feed everyday while the blank control group were fed basic feed. Shrimps were fed with a complete breeding cycle (95days) in the farm. Sampled at Day 45, 52, 59, 66, 73, the method of high throughput sequencing of 16S rDNA gene''s V4 region was used to determine diversity and composition of bacterial communities in each of these samples. Experiment showed: (1) The growth rate of the experimental group was average 15.2% higher than the blank control group. (2) The intestinal microflora of L.vannamei contained high proportion of Proteobacteria and Bacteroidetes, while Firmicutes, Verrucomicrobia, Planctomycetes, Actinobacteria were at lower rate. (3) In intestinal microflora of the blank control group'' shrimps, the average proportion of Proteobacteria (68.30%) was higher than the experimental group (57.94%), while Bacteroidetes was lower than the control group. Proteobacteria was mainly composed of Vibrio, Anaerospora and Rhodovulum. The blank control group'' average proportion of Vibrio was 5.40%, while the experimental group was 1.94%. Bacteroidete was mainly of Lutimonas and Tenacibaculum. The blank control group'' average proportion of Lutimonas was 5.56%, while the experimental group was 8.12%. The results of the study suggest that dietary with Bacillus cereus can change the intestinal microflora of L. vannamei and enhance its growth.