Table_3_Aflatoxin contamination of maize and groundnut in Burundi: Distribution of contamination, identification of causal agents and potential biocontrol genotypes of Aspergillus flavus.pdf

Aflatoxin contamination of the staples maize and groundnut is a concern for health and economic impacts across sub-Saharan Africa. The current study (i) determined aflatoxin levels in maize and groundnut collected at harvest in Burundi, (ii) characterized populations of Aspergillus section Flavi associated with the two crops, and (iii) assessed aflatoxin-producing potentials among the recovered fungi. A total of 120 groundnut and 380 maize samples were collected at harvest from eight and 16 provinces, respectively. Most of the groundnut (93%) and maize (87%) contained aflatoxin below the European Union threshold, 4 μg/kg. Morphological characterization of the recovered Aspergillus section Flavi fungi revealed that the L-morphotype of A. flavus was the predominant species. Aflatoxin production potentials of the L-morphotype isolates were evaluated in maize fermentations. Some isolates produced over 137,000 μg/kg aflatoxin B1. Thus, despite the relatively low aflatoxin levels at harvest, the association of both crops with highly toxigenic fungi poses significant risk of post-harvest aflatoxin contamination and suggests measures to mitigate aflatoxin contamination in Burundi should be developed. Over 55% of the L-morphotype A. flavus did not produce aflatoxins. These atoxigenic L-morphotype fungi were characterized using molecular markers. Several atoxigenic genotypes were detected across the country and could be used as biocontrol agents. The results from the current study hold promise for developing aflatoxin management strategies centered on biocontrol for use in Burundi to reduce aflatoxin contamination throughout the value chain.

黄曲霉毒素对主食玉米和大豆的污染，对撒哈拉以南非洲地区的健康与经济影响构成了一项重大关切。本研究（i）测定了在布隆迪收获时节收集的玉米和大豆中的黄曲霉毒素含量，（ii）对与两种作物相关的曲霉属（Aspergillus section Flavi）种群进行了鉴定，（iii）评估了从回收的真菌中产生的黄曲霉毒素潜力。共收集了120份大豆和380份玉米样本，分别来自八个和十六个省份。大部分大豆（93%）和玉米（87%）中的黄曲霉毒素含量低于欧盟的阈值，即每千克4微克。对回收的曲霉属（Aspergillus section Flavi）真菌的形态学特征分析显示，黄曲霉（A. flavus）的L型形态是优势种。对L型形态的分离株在玉米发酵中的黄曲霉毒素产生潜力进行了评估。一些分离株产生的黄曲霉毒素B1含量超过137,000微克/千克。尽管收获时的黄曲霉毒素水平相对较低，但两种作物与高度产毒真菌的关联仍构成了显著的收获后黄曲霉毒素污染风险，并暗示了在布隆迪制定减轻黄曲霉毒素污染的措施的必要性。超过55%的L型形态黄曲霉不产生黄曲霉毒素。这些非产毒的L型形态真菌通过分子标记进行了鉴定。在全国范围内检测到多种非产毒基因型，这些基因型可作为生物防治剂使用。本研究的结果为在布隆迪开发以生物防治为中心的黄曲霉毒素管理策略，以在整个产业链中降低黄曲霉毒素污染提供了希望。