Diastatic yeasts are a major contamination risk to packaged beer. Brewery quality control programs rely on selective microbial growth media and molecular detection of the STA1 gene, however there is a wide functional range of diastatic activity that remains unresolved by these current methods. Herein, we provide a comprehensive analysis of diastatic yeast selection media using our collection of STA1+ strains. For the preparation of microbial selection media, we highlight several factors to control including plate age, autoclave cycling conditions, cupric sulfate and dipotassium phosphate concentrations. We further present several functional assays that confirm the variation in diastatic activity across STA1+ strains and show a clear correlation with earlier onset and increasing strength in strains that contain an intact STA1 promoter. Furthermore, we have developed robust and simple plate-based assay to confirm diastatic activity of potential contaminants. Collectively, these functional assays provide improved risk assessment of re-fermentation in packaged product with the potential for determining contaminant thresholds for different STA1+ strains and weighing in on the decision to dump beer or issue a product recall. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65

中文翻译：

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改进了酿酒酵母 STA1+ 菌株的功能测定和风险评估

糖化酵母是包装啤酒的主要污染风险。啤酒厂质量控制程序依赖于选择性微生物生长培养基和 STA1 基因的分子检测，但是目前这些方法仍未解决广泛的糖化活性功能范围。在此，我们使用我们收集的 STA1+ 菌株对糖化酵母选择培养基进行了全面分析。对于微生物选择培养基的制备，我们强调了几个需要控制的因素，包括板龄、高压釜循环条件、硫酸铜和磷酸二钾浓度。我们进一步提出了几种功能测定，证实了跨 STA1+ 菌株的糖化活性的变化，并显示出与含有完整 STA1 启动子的菌株的早期发病和强度增加的明显相关性。此外，我们开发了稳健且简单的基于平板的检测方法，以确认潜在污染物的糖化活性。总的来说，这些功能检测提供了改进的包装产品再发酵风险评估，有可能确定不同 STA1+ 菌株的污染物阈值，并权衡倾倒啤酒或发布产品召回的决定。1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 3 4 3 4 3 4 4 3 4 3 4 3 4 3 4 3 4 3 4 3 4 5 3 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 这些功能检测提供了改进的包装产品再发酵风险评估，有可能确定不同 STA1+ 菌株的污染物阈值，并权衡倾倒啤酒或发布产品召回的决定。1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 3 4 3 4 3 4 4 3 4 3 4 3 4 3 4 3 4 3 4 3 4 5 3 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 这些功能检测提供了改进的包装产品再发酵风险评估，有可能确定不同 STA1+ 菌株的污染物阈值，并权衡倾倒啤酒或发布产品召回的决定。1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 3 4 3 4 3 4 4 3 4 3 4 3 4 3 4 3 4 3 4 3 4 5 3 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65