Lauterbach Alexander, Usbeck Julia C, Behr Jürgen, Vogel Rudi F
Lehrstuhl für Technische Mikrobiologie, Technische Universität München, Freising, Germany.
Bavarian Center for Biomolecular Mass Spectrometry, Freising, Germany.
PLoS One. 2017 Aug 9;12(8):e0181694. doi: 10.1371/journal.pone.0181694. eCollection 2017.
Brewing yeasts of the genus Saccharomyces are either available from yeast distributor centers or from breweries employing their own "in-house strains". During the last years, the classification and characterization of yeasts of the genus Saccharomyces was achieved by using biochemical and DNA-based methods. The current lack of fast, cost-effective and simple methods to classify brewing yeasts to a beer type, may be closed by Matrix Assisted Laser Desorption/Ionization-Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) upon establishment of a database based on sub-proteome spectra from reference strains of brewing yeasts. In this study an extendable "brewing yeast" spectra database was established including 52 brewing yeast strains of the most important types of bottom- and top-fermenting strains as well as beer-spoiling S. cerevisiae var. diastaticus strains. 1560 single spectra, prepared with a standardized sample preparation method, were finally compared against the established database and investigated by bioinformatic analyses for similarities and distinctions. A 100% separation between bottom-, top-fermenting and S. cerevisiae var. diastaticus strains was achieved. Differentiation between Alt and Kölsch strains was not achieved because of the high similarity of their protein patterns. Whereas the Ale strains show a high degree of dissimilarity with regard to their sub-proteome. These results were supported by MDS and DAPC analysis of all recorded spectra. Within five clusters of beer types that were distinguished, and the wheat beer (WB) cluster has a clear separation from other groups. With the establishment of this MALDI-TOF MS spectra database proof of concept is provided of the discriminatory power of this technique to classify brewing yeasts into different major beer types in a rapid, easy way, and focus brewing trails accordingly. It can be extended to yeasts for specialty beer types and other applications including wine making or baking.
酿酒酵母属的酿造酵母可从酵母经销商中心获得，也可从使用自家“内部菌株”的啤酒厂获得。在过去几年中，通过生化和基于DNA的方法对酿酒酵母属的酵母进行了分类和鉴定。目前缺乏快速、经济高效且简单的方法将酿造酵母分类到啤酒类型，基于酿造酵母参考菌株的亚蛋白质组谱建立数据库后，基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）可能会解决这一问题。在本研究中，建立了一个可扩展的“酿造酵母”谱数据库，其中包括52株最重要的底层发酵和顶层发酵菌株以及啤酒腐败性酿酒酵母变种糖化酵母菌株。最终，将用标准化样品制备方法制备的1560个单谱与已建立的数据库进行比较，并通过生物信息学分析研究其异同。实现了底层发酵、顶层发酵和酿酒酵母变种糖化酵母菌株之间的100%分离。由于阿尔特和科隆啤酒菌株的蛋白质模式高度相似，因此未能实现它们之间的区分。而淡色艾尔菌株的亚蛋白质组显示出高度的差异。所有记录谱的MDS和DAPC分析支持了这些结果。在区分出的五类啤酒类型中，小麦啤酒（WB）类与其他组有明显分离。通过建立这个MALDI-TOF MS谱数据库，证明了该技术具有快速、简便地将酿造酵母分类到不同主要啤酒类型的鉴别能力，并据此聚焦酿造试验。它可以扩展到特种啤酒类型的酵母以及包括酿酒或烘焙在内的其他应用。
