小麦粉污染霉菌的分离鉴定及产黄曲霉毒素 能力的研究

目的对污染小麦粉中所含霉菌进行分离和菌株鉴定,并对所分离菌株的产黄曲霉毒素能力进行评价。方法使用马铃薯-葡萄糖琼脂培养基和麦汁琼脂培养基对小麦粉污染的霉菌进行分离和纯化,根据菌落形态、显微形态观察和ITS序列分析结果对分离菌株进行鉴定,采用PCR技术检测黄曲毒霉合成路径的关键基因来判断菌株的潜在产毒能力,最后用高效液相色谱法确认菌株是否产毒。结果共分离出5株菌株,分别鉴定为链格孢霉(NHF1)、橘灰青霉(NHF2)、黑曲霉(NHF3)和米曲霉(NHF4、NHF5),其中2株米曲霉具有潜在的产黄曲霉素的能力,在一定条件下会产生黄曲霉毒素。结论需要加强小麦粉微生物检测,尤其是霉菌污染的检测、管理和控制,全面制定小麦粉中污染微生物的限量标准,尤其是霉菌的限量值。

Isolation, identification and appraisal of aflatoxin-producing ability of molds from contaminated wheatmeal

Objective To isolate and identify the molds from contaminated wheatmeal, and to evaluate aflatoxin-producing ability of the molds. Methods The molds from contaminated wheatmeal were isolated and purified by PDA (the potato-glucose agar) medium and wortagar medium, then were identified according to colony morphology and microscopical morphology together with ITS sequence analysis results. The potential of aflatoxin-producing ability was judged by detecting the key genes in aflatoxin synthesis pathway with PCR, and then was confirmed by detecting the metabolite with HPLC (high performance liquid chromatography). Results Totally 5 strains were isolated and identified as Alternaria alternate (NHF1), Penicillium auantiogriseum (NHF2), Aspergillus niger (NHF3), and Aspergillus oryzae (NHF4, NHF5). Two of Aspergillusoryzae had potential aflatoxin-producing ability and were able to produce aflatoxin under certain conditions. Conclusion The microbiological detection of wheatmeal need to be paid more attention especially for the detection and control of molds contamination. Microbial limit standard especially molds limit value need to be formulated.