Interactions of Saprophytic Yeasts with a nor Mutant of Aspergillus flavus

The nor mutant of Aspergillus flavus has a defective norsolorinic acid reductase, and thus the aflatoxin biosynthetic pathway is blocked, resulting in the accumulation of norsolorinic acid, a bright red-orange pigment. We developed a visual agar plate assay to monitor yeast strains for their ability to inhibit aflatoxin production by visually scoring the accumulation of this pigment of the nor mutant. We identified yeast strains that reduced the red-orange pigment accumulation in the nor mutant. These yeasts also reduced aflatoxin accumulation by a toxigenic strain of A. flavus. These yeasts may be useful for reducing aflatoxin contamination of food commodities.

黄曲霉（Aspergillus flavus）的nor突变体存在诺氏酸还原酶（norsolorinic acid reductase）功能缺陷，导致其黄曲霉毒素（aflatoxin）生物合成通路被阻断，最终造成亮红橙色色素诺氏酸（norsolorinic acid）的积累。我们开发了一种可视化琼脂平板检测法（visual agar plate assay），通过对该nor突变体的该色素积累水平进行目视评分，来监测酵母菌菌株抑制黄曲霉毒素生成的能力。我们筛选得到了可降低该nor突变体中红橙色色素积累的酵母菌菌株，这类菌株同样能够抑制产毒黄曲霉菌株的黄曲霉毒素积累。该类酵母菌或可用于降低食品类商品的黄曲霉毒素污染。