Laboratory of Genetics, Wageningen University and Research, Wageningen, The Netherlands.
Mycotoxicology Laboratory, National Institute for Scientific and Industrial Research, Lusaka, Zambia.
Mycotoxin Res. 2024 Aug;40(3):351-367. doi: 10.1007/s12550-024-00532-7. Epub 2024 Apr 22.
Aspergillus section Flavi (Flavi) is a diverse group of fungal species whose common members include A. flavus and A. parasiticus. These are well-known for the production of aflatoxin (AF) B and G and other toxic metabolites, like cyclopiazonic acid (CPA). They are saprophytic soil dwellers and also become crop opportunistic epiphytes. The consequence is contamination of the crop with mycotoxins, such as carcinogenic AF. We investigated the Flavi community structure of maize and that of their surrounding soil, including their mycotoxigenicity. Furthermore, we investigated the link of the maize Flavi diversity with preharvest maize AF levels. The study was carried out in four selected districts of Zambia, in a low rainfall zone. The Flavi characterisation was triphasic, involving morphological (colony colour and sclerotia formation), metabolic (AF and CPA production) and genetic (calmodulin gene polymorphism) analyses. Flavi abundance was determined by dilution plate technique on modified rose Bengal agar. Results showed that Flavi communities on maize and in soil differed. Maize had a higher Flavi species diversity than soil. A. parasiticus dominated the soil community by frequency of field appearance (85%), while maize was dominated by A. minisclerotigenes (45%). CPA-producers with or without AF production dominated the maize (65%) while producers of only AF (B/G) dominated the soil (88%). The ratio between maize A. parasiticus and A. minisclerotigenes abundance seemed to have had a bearing on the levels of AF in maize, with a ratio close to 1:1 having higher levels than a pure community of either A. parasiticus or A. minisclerotigenes.
黄曲霉（Flavi）是一组多样化的真菌物种，其常见成员包括黄曲霉和寄生曲霉。这些物种以产生黄曲霉毒素（AF）B 和 G 以及其他有毒代谢物（如环匹阿尼酸（CPA））而闻名。它们是腐生土壤居民，也是作物机会性附生菌。结果是作物受到真菌毒素的污染，如致癌的 AF。我们研究了玉米及其周围土壤中的 Flavi 群落结构，包括它们的产毒能力。此外，我们还研究了玉米 Flavi 多样性与收获前玉米 AF 水平之间的联系。该研究在赞比亚的四个选定地区进行，这些地区属于低降雨量区。Flavi 的特征分析是三相的，涉及形态学（菌落颜色和菌核形成）、代谢学（AF 和 CPA 生产）和遗传学（钙调蛋白基因多态性）分析。Flavi 的丰度通过在改良孟加拉玫瑰琼脂上的稀释平板技术来确定。结果表明，玉米上和土壤中的 Flavi 群落不同。玉米上的 Flavi 物种多样性高于土壤。寄生曲霉通过田间出现的频率（85%）主导土壤群落，而玉米则以小梗青霉为主（45%）。同时产生 CPA 和 AF 的生产者或只产生 AF（B/G）的生产者主导玉米（65%），而只产生 AF（B/G）的生产者主导土壤（88%）。玉米中寄生曲霉和小梗青霉丰度的比值似乎对玉米中 AF 的水平有影响，比值接近 1:1 的比单一的寄生曲霉或小梗青霉群落具有更高的水平。
