Solanki Manoj Kumar, Abdelfattah Ahmed, Sadhasivam Sudharsan, Zakin Varda, Wisniewski Michael, Droby Samir, Sionov Edward
Volcani Center, Agricultural Research Organization, Institute of Postharvest and Food Sciences, Rishon LeZion 7528809, Israel.
Institute of Environmental Biotechnology, Graz University of Technology, Petersgasse 12, A-8010 Graz, Austria.
J Fungi (Basel). 2021 Sep 20;7(9):781. doi: 10.3390/jof7090781.
Wheat grains are colonized by complex microbial communities that have the potential to affect seed quality and susceptibility to disease. Some of the beneficial microbes in these communities have been shown to protect plants against pathogens through antagonism. We evaluated the role of the microbiome in seed health: in particular, against mycotoxin-producing fungi. Amplicon sequencing was used to characterize the seed microbiome and determine if epiphytes and endophytes differ in their fungal and bacterial diversity and community composition. We then isolated culturable fungal and bacterial species and evaluated their antagonistic activity against mycotoxigenic fungi. The most prevalent taxa were found to be shared between the epiphytic and endophytic microbiota of stored wheat seeds. Among the isolated bacteria, strains exhibited strong antagonistic properties against fungal pathogens with noteworthy fungal load reduction in wheat grain samples of up to a 3.59 log CFU/g compared to untreated controls. We also found that a strain of the yeast, , isolated from wheat grains, degrades and/or metabolizes aflatoxin B, one of the most dangerous mycotoxins that negatively affects physiological processes in animals and humans. The mycotoxin level in grain samples was significantly reduced up to 65% in the presence of the yeast strain, compared to the untreated control. Our study demonstrates that stored wheat grains are a rich source of bacterial and yeast antagonists with strong inhibitory and biodegradation potential against mycotoxigenic fungi and the mycotoxins they produce, respectively. Utilization of these antagonistic microorganisms may help reduce fungal and mycotoxin contamination, and potentially replace traditionally used synthetic chemicals.
小麦籽粒被复杂的微生物群落定殖，这些群落有可能影响种子质量和对疾病的易感性。这些群落中的一些有益微生物已被证明可通过拮抗作用保护植物免受病原体侵害。我们评估了微生物组在种子健康中的作用：特别是针对产生霉菌毒素的真菌。扩增子测序用于表征种子微生物组，并确定附生菌和内生菌在真菌和细菌多样性及群落组成方面是否存在差异。然后，我们分离出可培养的真菌和细菌物种，并评估它们对产毒真菌的拮抗活性。发现最普遍的分类群存在于储存小麦种子的附生和内生微生物群之间。在分离出的细菌中，一些菌株对真菌病原体表现出很强的拮抗特性，与未处理的对照相比，小麦籽粒样品中的真菌载量显著降低，最多可降低3.59 log CFU/g。我们还发现，从小麦籽粒中分离出的一种酵母菌株可降解和/或代谢黄曲霉毒素B，黄曲霉毒素B是最危险的霉菌毒素之一，会对动物和人类的生理过程产生负面影响。与未处理的对照相比，在酵母菌株存在的情况下，谷物样品中的霉菌毒素水平显著降低了65%。我们的研究表明，储存的小麦籽粒是细菌和酵母拮抗剂的丰富来源，它们分别对产毒真菌及其产生的霉菌毒素具有很强的抑制和生物降解潜力。利用这些拮抗微生物可能有助于减少真菌和霉菌毒素污染，并有可能取代传统使用的合成化学品。
