Mixed culture fermentation with lager yeast is relatively new in brewing. Maintaining the proportion of strains during fermentation is important to assure the quality of beer and accordingly needs to be monitored. The current discriminatory methods have limited application for lager strains. In the present study, a rapid method to monitor the strain proportion of strains in mixed samples of two different lager yeast strains was developed using microsatellite polymerase chain reaction (PCR) and GeXP Genetic Analysis System. Microsatellite markers in the lager yeast genome were searched using SSR Hunter software. Quantitative PCR using these microsatellite markers was performed and PCR products were analysed by capillary electrophoresis. One locus ‐ mitochondrial carnitine acetyltransferase – was found to discriminate the two strains. A standard curve was generated based on the premixed samples of the two strains enabling the proportion of the stains to be determined. This method is a fast and reliable approach to monitor the strain proportion of mixed lager yeast fermentation. © 2020 The Institute of Brewing & Distilling

中文翻译：

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使用微卫星PCR和GeXP定量混合啤酒混合物中的菌株

与啤酒混合培养发酵在酿造中相对较新。在发酵过程中保持菌株比例非常重要，以确保啤酒质量，因此需要进行监控。当前的区分方法在较大菌株中的应用有限。在本研究中，使用微卫星聚合酶链反应（PCR）和GeXP遗传分析系统，开发了一种快速的方法来监测两种不同的大型酵母菌株混合样品中菌株的比例。使用SSR Hunter软件搜索更大的酵母基因组中的微卫星标记。使用这些微卫星标记进行定量PCR，并通过毛细管电泳分析PCR产物。发现一个位点线粒体肉碱乙酰基转移酶可以区分这两种菌株。基于两种菌株的预混合样品产生标准曲线，从而能够确定污渍的比例。该方法是一种快速可靠的方法，用于监控混合啤酒发酵的菌株比例。©2020酿酒与蒸馏研究所