Okayo Robert O, Andika Darius O, Dida Mathews M, K'Otuto George O, Gichimu Bernard M
Department of Plant, Animal and Food Sciences, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya.
Department of Applied Sciences, Maseno University, Maseno, Kenya.
Int J Microbiol. 2020 Sep 7;2020:8854718. doi: 10.1155/2020/8854718. eCollection 2020.
Pathogenesis of on important agricultural products is a key concern on human health due to the synthesis and secretion of the hazardous secondary metabolite, aflatoxin. This study identified and further characterized aflatoxigenic from groundnuts sampled from sundry shops in Kenya using integrated morphological and molecular approaches. The groundnuts were plated on potato dextrose agar for isolation and morphological observation of based on macroscopic and microscopic features. Molecular characterization was done through amplification and comparison of the partial sequence of the ITS1-5.8S-ITS2 region. The expression analysis of , , , and genes in the aflatoxin biosynthesis pathways was conducted to confirm the positive identification of . The gene expression also aided to delineate toxigenic isolates of from atoxigenic ones. Morphologically, 18 isolates suspected to be were identified. Out of these, 14 isolates successfully amplified the 500 bp ITS region of or while 4 isolates were not amplified. All the remaining 14 isolates expressed at least one of the aflatoxigenic genes but only 5 had all the genes expressed. Partial sequencing revealed that isolates 5, 11, 12, 13, and 15 had 99.2%, 97.6%, 98.4%, 97.5%, and 100% homology, respectively, to the isolate LUOHE, ITS-5.8S-ITS2, obtained from the NCBI database. The five isolates were accurate identification of atoxigenic . Precise identification of toxigenic strains of will be useful in establishing control strategies of the fungus in food products.
重要农产品上的黄曲霉致病机制是人类健康的关键关注点，因为其会合成并分泌有害的次生代谢产物黄曲霉毒素。本研究采用综合形态学和分子学方法，从肯尼亚杂货店采集的花生中鉴定并进一步表征产黄曲霉毒素的黄曲霉。将花生接种在马铃薯葡萄糖琼脂上，基于宏观和微观特征进行分离及黄曲霉的形态学观察。通过扩增和比较ITS1-5.8S-ITS2区域的部分序列进行分子表征。对黄曲霉毒素生物合成途径中的、、、和基因进行表达分析，以确认黄曲霉的阳性鉴定。基因表达也有助于区分产毒黄曲霉分离株和无毒黄曲霉分离株。在形态学上，鉴定出18株疑似黄曲霉的分离株。其中，14株分离株成功扩增出黄曲霉或寄生曲霉500 bp的ITS区域，而4株未扩增出来。其余14株分离株均至少表达一种产黄曲霉毒素基因，但只有5株所有基因均表达。部分测序显示，分离株5、11、12、13和15与从NCBI数据库获得的黄曲霉分离株LUOHE的ITS-5.8S-ITS2分别具有99.2%、97.6%、98.4%、97.5%和100%的同源性。这五株分离株被准确鉴定为产毒黄曲霉。准确鉴定黄曲霉的产毒菌株将有助于制定食品中该真菌的控制策略。
