Department of Veterinary and Microbiological Sciences, North Dakota State University, Dept. 7690, PO Box 6050, Fargo, ND 58108-6050, United States.
Int J Food Microbiol. 2011 Nov 1;150(2-3):150-6. doi: 10.1016/j.ijfoodmicro.2011.07.032. Epub 2011 Aug 3.
Fusarium can survive, grow, and produce mycotoxins during malting. We evaluated the percentage of barley kernels infected with Fusarium (FI) and deoxynivalenol (DON) concentration in three barley treatments (high-quality, naturally infected, and Fusarium graminearum inoculated barley) during various stages of malting. We also applied real-time polymerase chain reaction (real-time PCR) and real-time reverse transcriptase PCR (real-time RT-PCR) methods to quantify trichothecene-producing (Tri5) DNA concentration and expression, respectively. We observed that FI significantly (P<0.05) increased during the germination stage of malting in all barley treatments. Temperatures of 49°C and higher during kilning reduced the FI in high-quality barley treatments, but for inoculated treatments temperatures in excess of 60°C were needed to reduce FI. The Tri5 DNA concentration ranged from non-detectable to 3.9 ng/50mg, 0.1 to 109.8 ng/50mg and 3.4 to 397.5 ng/50 mg in malted high-quality, inoculated and naturally infected barley treatments respectively. Strong gene expression (Tri5) in naturally infected barley treatments was found during the third day of germination, when compared to high-quality and inoculated barley treatments during malting. Deoxynivalenol was present even at high kilning temperatures, as DON is heat stable. The average DON concentration ranged from non-detectable to 0.1 μg/g, non-detectable to 1.1 μg/g, and 1.5 to 45.9 μg/g during various stages of malting in high-quality, inoculated and infected barley and malt samples respectively. Overall, the last 2 days of germination and initial stages of kilning were peak stages for FI, Tri5 gene production, Tri5 gene expression and DON production.
镰刀菌可在制麦过程中存活、生长并产生真菌毒素。我们评估了在制麦的不同阶段，三种大麦处理（高质量、自然感染和接种镰刀菌的大麦）中感染镰刀菌（FI）的大麦籽粒比例和脱氧雪腐镰刀菌烯醇（DON）浓度。我们还应用实时聚合酶链反应（real-time PCR）和实时逆转录聚合酶链反应（real-time RT-PCR）方法分别定量产三萜烯（Tri5）DNA 浓度和表达。我们观察到，在所有大麦处理的发芽阶段，FI 显著（P<0.05）增加。干燥过程中 49°C 及以上的温度降低了高质量大麦处理中的 FI，但接种处理需要超过 60°C 的温度才能降低 FI。Tri5 DNA 浓度在制麦的高质量、接种和自然感染大麦处理中分别为不可检测到 3.9ng/50mg、0.1 到 109.8ng/50mg 和 3.4 到 397.5ng/50mg。在制麦过程中，与高质量和接种大麦处理相比，自然感染大麦处理中在第三天发芽时发现了强烈的基因表达（Tri5）。即使在高温干燥下也存在 DON，因为 DON 具有热稳定性。在制麦的不同阶段，高质量、接种和感染大麦和麦芽样品中的 DON 浓度平均分别为不可检测到 0.1μg/g、不可检测到 1.1μg/g 和 1.5 到 45.9μg/g。总体而言，发芽的最后两天和干燥的初始阶段是 FI、Tri5 基因产生、Tri5 基因表达和 DON 产生的高峰期。
