Fusarium head blight (FHB) and the occurrence of mycotoxins is the largest food safety threat to malting and brewing grains. Worldwide surveys of commercial beers have reported that the trichothecene mycotoxin deoxynivalenol (DON) is the most frequent contaminant in beer. Although the DON content of grain generally declines during steeping due to its solubilization, Fusarium spp. can continue to grow and produce DON from steeping through the early kilning stage of malting. DON present on malt is largely extracted into beer. The objective of the current study was to localize the growth of Fusarium spp. within FHB-infected kernels by developing an improved method and to associate fungal growth with the production of DON during malting. FHB-infected barley, wheat, rye, and triticale grains that exhibited large increases in the amount of Fusarium Tri5 DNA and trichothecene mycotoxins following malting were screened for hyphal localization. The growth of fungal hyphae associated with grain and malt was imaged by scanning electron microscopy and confocal laser-scanning microscopy assisted with WGA-Alexa Fluor 488 staining, respectively. In barley, hyphae were present on or within the husk, vascular bundle, and pericarp cavities. Following malting, vast hyphal growth was observed not only in these regions but also in the aleurone layer, endosperm, and embryo. Extensive fungal growth was also observed following malting of wheat, rye, and triticale. However, these grains already had an extensive internal presence of Fusarium hyphae in the unmalted grain, thus representing an enhanced chance of fungal expansion during the malting.

Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

镰刀菌赤霉病 (FHB) 和霉菌毒素的出现是对麦芽和酿造谷物的最大食品安全威胁。全球商业啤酒调查报告称，单端孢霉烯霉菌毒素脱氧雪腐镰刀菌烯醇 (DON) 是啤酒中最常见的污染物。尽管谷物的 DON 含量由于其溶解作用而在浸泡过程中通常会下降，但镰刀菌属。可以继续生长并从麦芽制造的早期窑炉阶段浸泡产生 DON。麦芽中的 DON 大部分被提取到啤酒中。当前研究的目的是定位镰刀菌的生长属 通过开发一种改进的方法并将真菌生长与麦芽制造过程中 DON 的产生联系起来，在 FHB 感染的谷粒中进行检测。FHB 感染的大麦、小麦、黑麦和小黑麦谷物中镰刀菌 Tri5的数量显着增加对麦芽制造后的 DNA 和单端孢霉烯真菌毒素进行菌丝定位筛选。分别通过扫描电子显微镜和共聚焦激光扫描显微镜辅助 WGA-Alexa Fluor 488 染色对与谷物和麦芽相关的真菌菌丝的生长进行成像。在大麦中，菌丝存在于外壳、维管束和果皮腔上或内。发芽后，不仅在这些区域，而且在糊粉层、胚乳和胚胎中都观察到大量的菌丝生长。在小麦、黑麦和黑小麦发芽后也观察到大量真菌生长。然而，这些谷物在未发芽的谷物中已经存在大量的镰刀菌菌丝，因此表明在发芽过程中真菌繁殖的机会增加。

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