降解黄曲霉毒素B1菌株的发酵条件优化及降解机制

目的：鉴定一株降解黄曲霉毒素B1（aflatoxin B1，AFB1）的霉菌HSK8，通过优化其发酵条件提高AFB1降解率，并初步探索其降解机制。方法：通过形态学和内部转录间隔区（internal transcribed spacer，ITS）、18S rRNA和26S rRNA序列分析对该菌株进行鉴定，并通过单因素试验对发酵条件进行优化，采用薄层层析对AFB1降解产物进行研究。结果：经鉴定该株霉菌为夏孢生枝孢（Cladosporium uredinicola）。其发酵条件经优化确定为：发酵温度28 ℃、装液量75 mL/250 mL、接种量15%、发酵时间36 h、初始pH 8.0。薄层层析观察到一个不同于AFB1的荧光斑点。结论：发酵条件优化后，AFB1降解率从40.68%提升到68.96%，提高了69.52%；AFB1降解产物能在365 nm波长处发出蓝色荧光。

Optimization of Fermentation Condition for an AFB1-Degrading Strain and Preliminary Exploration of Degradation Mechanism

In this study, a mould isolated for degrading aflatoxin B1 was reported. Morphological studies coupled with
internal transcribed spacer (ITS), 18S ribosomal RNA gene sequence, 26S ribosomal RNA gene sequence analyses
indicated that the mould was Cladosporium uredinicola. Through single-factor experiments, the fermentation conditions
were determined as follows: temperature 28 ℃, medium loading volume 75 mL/250 mL, inoculumamount 15% (V/V),
fermentation time 36 h, initial pH 8.0. Under these conditions, the AFB1 degradation efficiency was 68.96%, a 69.52%
increase over that before optimization (40.68%). On the thin-layer chromatography (TLC) plate, a new dot was found which
exhibited blue fluorescence at 365 nm.