降解黄曲霉毒素B1的绿脓杆菌的分离、鉴定及应用研究

Isolation and Characterization of Pseudomonas Aeruginosa with Aflatoxin B1 Degradation Capacity and Its Detoxification Application

黄曲霉毒素B1(AFB1)是霉变粮食和饲料中常见的真菌毒素之一,对其进行脱毒研究具有重要意义。利用以香豆素为唯一碳氮源的培养基分离出9个菌株,对AFB1的降解率均超过60%,其中YM-1菌株的降解率为91.48%。对YM-1菌株的16S rDNA基因进行测序及序列比对,表明该菌株为绿脓杆菌(Pseudomonas aeruginosa)。对AFB1降解动力学研究发现,发酵96 h后YM-1绿脓杆菌可降解NB培养基中90.70%的AFB1,在24~48 h内降解速度最快,降解率为82.99%。绿脓杆菌YM-1发酵液中的降解活性主要位于发酵上清液中,同时细胞对AFB1也具有一定的吸附作用;蛋白酶K反应及热处理后的YM-1发酵上清液对AFB1的降解率明显降低,可初步判断上清液中可能存在可降解AFB1的酶类。将绿脓杆菌YM-1接种到含AFB1的霉变玉米粉中进行固态发酵6 d后,玉米粉中的AFB1降解了88.87%。

Aflatoxin B1(AFB1)is a common mycotoxin in moldy cereal grains and feedstuff,which seriously threaten their use and economic value.It is important to study detoxification of AFB1 in grains and feedstuff.In this study,nine microbial strains with AFB1 degradation capacity of above 60%were screened using medium containing coumarin as the sole carbon source.One of which,named YM-1,had the AFB1 degradation capacity of 91.48%.The sequence alignment of 16S rDNA of the YM-1 strain demonstrated that it was Pseudomonas aeruginosa.The degradation dynamics of AFB1 by P.aeruginosa YM-1 showed that 90.70%of AFB1 in NB medium was degraded after 96 h and the degradation rate of AFB1 was the highest between 24 h to 48 h.The AFB1-degrading activity of P.aeruginosa was predominantly attributed to the cell-free supernatant and the P.aeruginosa cell could also adsorb AFB1.The AFB1-degrading activity in the cell-free supernatant was found sensitive to proteinase K and heat treatments,indicating that the extracellular enzymes are responsible for the AFB1 degradation.Solid state fermentation of the P.aeruginosa YM-1 in moldy corn powder was performed and 88.87%of AFB1 in corn powder was reduced after 6 days.This study provides an experimental basis for the detoxification treatment of AFB1 contaminated cereal grain and feedstuff by P.aeruginosa.