一株功能益生菌的简易发酵及其在凡纳滨对虾(Litopenaeus vannamei)生物絮团养殖中的应用

摘要

Shrimp aquaculture,as one of the main components of the aquaculture industry,has produced enormous economic benefits and social benefits.But the sustainable development of the shrimp aquaculture has been affected and restricted by the discharge of the waste and the frequent occurrence of diseases.Bio-floc technology by adding brown sugar,molasses and other carbon source in breed pool to promote heterotrophic microbial growth and reproduction to control the water pollution,shows great prospects for development in shrimp culture.In this study,we established a method of simplified fermentation that used a strain of Bacillus megaterium with the activity of denitrification.And we used prawn feed and brown sugar as the medium.Results showed that the best ratio of medium was prawn feed 3 g/L,brown sugar 6 g/L and inoculation volume 1 × 108 CFU/ml through the orthogonal experiment.And the other conditions were optimized by single experiment.We got the fermentation products with the viable cell number was 1.16× 1010 CFU/ml that fermented with 31 ℃,40％ liquid volume and 24 hours.Then we fed the Litopenaeus vannamei through the bio-floc technology by using the fermentation products.The result showed that the volume of bio-floc was formed more quickly in dominated bio-floc group (added bacillus and sugar) than bio-floc group (just added sugar) and control (traditional culture pattern) (P＜0.05),and the overall concentration level of nitrite-N in dominated bio-floc group was much lower than the other groups (P＜0.05).At the end of the culture,the highest of the average body length and weight in prawns was obtained in dominated bio-floc group,and Bio-floc group and control were significantly lower (P＜0.05).This study established a simplified and feasible method for the fermentation of probiotic bacteria.And the results showed the effectiveness of the bio-floc technology in prawn culture is verified by the additiong probiotics.%对一株有脱氮作用的巨大芽孢杆菌(Bacillus megaterium)进行简易发酵,以对虾饲料及赤砂糖为培养基,通过正交实验及发酵条件优化,在对虾饲料3 g/L、赤砂糖6g/L、接种量1×108 CFU/ml、发酵温度31℃、装液量40％条件下,发酵24 h可获得活菌数为1.16× 1010 CFU/ml的发酵产物.使用发酵得到的巨大芽孢杆菌进行凡纳滨对虾(Litopenaeus vannamei)生物絮团养殖实验.结果显示,添加芽孢杆菌和赤砂糖的增强絮团组的絮团形成速度较添加赤砂糖的絮团组及传统养殖的对照组明显提升(P＜0.05),整体上增强絮团组的亚硝酸氮水平与絮团组和对照组差异显著(P＜0.05).养殖结束时,添加巨大芽孢杆菌组的对虾体长、体重水平均显著高于另2组.本研究建立了一种简单可行的功能益生菌发酵方式,并验证添加功能益生菌可提高生物絮团技术在对虾养殖中的效果.