De Roos Jonas, Verce Marko, Weckx Stefan, De Vuyst Luc
Research Group of Industrial Microbiology and Food Biotechnology (IMDO), Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
Front Microbiol. 2020 Jul 17;11:1692. doi: 10.3389/fmicb.2020.01692. eCollection 2020.
Lambic beer production processes are characterized by a temporal succession of well-adapted microbial species. Temporal metagenomic analysis of a Belgian, traditional, lambic beer production process, which was examined microbiologically and metabolomically before, confirmed that the microbial diversity is limited. Moreover, it allowed to link the consumption and production of certain compounds to specific microbial groups or species. Fermentation characteristics, such as the conversion of malic acid into lactic acid and acetoin production, were retrieved and could be attributed to specific microorganisms, namely and species, respectively. Traits previously ascribed to brewery-specific strains were confirmed during the lambic beer production process examined multiphasically; in particular, the higher production of 4-ethylguaiacol compared to 4-ethylphenol was further shown by mass spectrometric analysis. Moreover, the absence of phenolic acid decarboxylase in was shown culture-independently and could explain its late occurrence during the maturation phase. Furthermore, the potential of maltooligosaccharide degradation could be ascribed metagenomically to not only species but also , possibly explaining their degradation early in the lambic beer production process. Also, acetic acid bacteria (AAB) seemed to be able to consume maltooligosaccharides via their conversion into trehalose. Furthermore, these AAB possessed esterase genes, potentially capable of forming ethyl acetate, which may contribute to the flavor of lambic beer. Improved knowledge on the reasons behind certain community dynamics and the role of the different microorganisms in terms of potential functionality could improve brewery practices to assure to produce more quality-stable end-products.
兰比克啤酒的生产过程具有一系列适时适应的微生物物种相继出现的特点。对一个比利时传统兰比克啤酒生产过程进行的时间宏基因组分析，此前已对其进行过微生物学和代谢组学检测，证实其微生物多样性有限。此外，该分析还能将某些化合物的消耗和产生与特定的微生物群体或物种联系起来。诸如苹果酸转化为乳酸以及乙偶姻产生等发酵特性得以确定，且可分别归因于特定的微生物，即 和 物种。在多阶段检测的兰比克啤酒生产过程中，先前归因于啤酒厂特定 菌株的特性得到了证实；特别是，质谱分析进一步表明，与4 - 乙基苯酚相比，4 - 乙基愈创木酚的产量更高。此外，通过不依赖培养的方法表明 中不存在酚酸脱羧酶，这可以解释其在成熟阶段出现较晚的现象。此外，麦芽低聚糖降解的潜力从宏基因组学角度不仅可归因于 物种，还可归因于 ，这可能解释了它们在兰比克啤酒生产过程早期的降解情况。而且，醋酸菌似乎能够通过将麦芽低聚糖转化为海藻糖来消耗它们。此外，这些醋酸菌拥有酯酶基因，可能能够形成乙酸乙酯，这可能对兰比克啤酒的风味有贡献。对某些群落动态背后的原因以及不同微生物在潜在功能方面的作用有更深入的了解，可能会改进啤酒厂的生产实践，以确保生产出质量更稳定的最终产品。
