嗜热链球菌等六种微生物对AFB1降解能力的研究

Degradation of Aflatoxin B1 by six kinds of microorganisms including Streptococcus thermophilus

霉菌毒素是霉菌产生的有毒的次级代谢产物,目前饲料中黄曲霉毒素B1(Aflatoxin B1,AFB1)污染呈现分布广、检出率高的趋势,为寻求一种高效、安全、经济和绿色的降解和脱毒方法,研究选择迟缓芽孢杆菌、短小芽孢杆菌、罗伊氏乳杆菌、乳酸片球菌、嗜热链球菌、米曲霉6种饲料中允许添加的微生物分别与AFB1共培养,采用高效液相色谱-质谱联用法检测AFB1残留量和降解产物。利用筛选出的高效菌株,选择接种量、时间、温度和水分作为试验因素,在单因素试验的基础上,运用二次回归正交旋转组合设计方法进行优化,建立回归模型方程并筛选最佳发酵条件。结果显示,嗜热链球菌对AFB1的降解效果最好,降解率为80.00%,降解率显著(P<0.05)高于其他几种菌;降解产物中含有AFM1,没有发现黄曲霉毒醇;最佳发酵条件为:发酵时间120 h、发酵水分65%、发酵温度44℃、接种量7×10^8CFU/g。说明嗜热链球菌可以用于降解饲料中的AFB1,为减少霉变饲料中AFB1的危害提供了理论依据和数据支撑。

Mycotoxin is a toxic secondary metabolite produced by mold.At present,the contamination of aflatoxin B1(AFB1)in feed has a wide distribution and high detection rate,in order to seek a kind of efficient,safe,economical and green method for the degradation and detoxification.Microorganisms allowed to be added in feeds including Bacillus lentus,Bacillus brevis,Lactobacillus reuteri,Pediococcus lactis,Streptococcus thermophilus and Aspergillus oryzae were co-cultured with AFB1.HPLC-MS was used to detect AFB1 residues and degradation products.Using the selected high-efficiency strains,selecting the inoculum size,time,temperature and moisture as the experimental factors,based on the single factor experiment,using the quadratic regression orthogonal rotation combination design method to optimize,establish the regression model equation and screen the best fermentation condition.The results showed that the degradation of AFB1 by Streptococcus thermophilus was the best,the degradation rate was 80.00%,the degradation rate was significantly higher(P<0.05)than other bacteria;the degradation products contained AFM1,no aflatoxin was found;The fermentation conditions were as follows:fermentation time 120 h,fermentation water 65%,fermentation temperature 44℃,inoculum size 7×10^8 CFU/g.It is indicated that Streptococcus thermophilus can be used to degrade AFB1 in feed,which provides theoretical basis and data support for reducing the damage of AFB1 in moldy feed.