赭曲霉毒素A脱毒菌株的筛选与鉴定

Screening and Identification of an Ochratoxin A-Detoxifying Strain

赭曲霉毒素A(ochratoxin A,OTA)是一种广泛分布于各类农产品中的真菌毒素,对人类和动物的健康造成威胁。为探究OTA的体外生物脱毒方法,本实验尝试从小鼠肠道中筛选出脱除OTA的菌株。首先以1 kg体质量添加210 μg OTA的饲料饲喂BALB/c小鼠,收集其粪便,然后利用添加一定质量浓度OTA的LB固体培养基从粪便中逐步筛选出12株在高质量浓度OTA环境下依然能够大量生长繁殖的菌株,全部接种于LB液体培养基培养20 h后,以高效液相色谱法检测该12株菌体外脱除OTA的效果。结果发现其中1株菌YH7能够高效脱除OTA,脱毒效率达到84.6%。从生理学、16S rDNA序列比对等方面分析,最终确定YH7为大肠杆菌(Escherichia coli)。通过单因素优化法确定YH7的最适生长条件为pH 7.5、37℃和200 r/min的摇床速率。

Ochratoxin A（OTA） is an important mycotoxin that contaminates a variety of agricultural products, thus posing a serious threat on the health of humans and animals. To find a new method for the biological detoxification of OTA in vitro, in this study, we attempted to isolate and screen intestinal bacteria from mice for OTA detoxification. Firstly, BALB/c mice were fed on a diet containing 210 μg of OTA per kg of body mass, and their faeces were collected for successive isolation of 12 strains capable of growing well at high OTA concentration using solid Luria-Bertani（LB） medium with a certain concentration of OTA. All these strains were cultivated in liquid LB broth for 20 h and their OTA-detoxifying abilities were then tested by high performance liquid chromatography（HPLC）. The results showed that one strain, named YH7, exhibited strong ability to remove OTA with a maximum efficiency of 84.6%. Then YH7 was identified as Escherichia coli by its morphological features and 16 S rDNA sequencing. This strain grew best at pH 7.5 and 37 ℃ with shaking at 200 r/min.