Labuschagne Pwj, Divol B
South African Grape and Wine Research Institute, Department of Viticulture and Oenology, Private Bag X1, Matieland, 7602, South Africa.
Appl Microbiol Biotechnol. 2021 Feb;105(3):953-973. doi: 10.1007/s00253-020-11080-2. Epub 2021 Jan 6.
Alcoholic fermentation is a crucial step of winemaking, during which yeasts convert sugars to alcohol and also produce or biotransform numerous flavour compounds. In this context, nutrients are essential compounds to support yeast growth and ultimately ensure complete fermentation, as well as optimized production of flavour compounds over that of off-flavour compounds. In particular, the vitamin thiamine not only plays an essential cofactor role for several enzymes involved in various metabolic pathways, including those leading to the production of wine-relevant flavour compounds, but also aids yeast survival via thiamine-dependent stress protection functions. Most yeast species are able to both assimilate exogenous thiamine into the cell and synthesize thiamine de novo. However, the mechanism and level of thiamine accumulation depend on several factors. This review provides an in-depth overview of thiamine utilization and metabolism in the model yeast species Saccharomyces cerevisiae, as well as the current knowledge on (1) the intracellular functions of thiamine, (2) the balance between and regulation of uptake and synthesis of thiamine and (3) the multitude of factors influencing thiamine availability and utilization. For the latter, a particular emphasis is placed on conditions occurring during wine fermentation. The adequacy of thiamine concentration in grape must to ensure successful fermentation is discussed together with the effect of thiamine concentration on fermentation kinetics and on wine sensory properties. This knowledge may serve as a resource to optimise thiamine concentrations for optimal industrial application of yeasts. KEY POINTS: • Thiamine uptake is preferred over biosynthesis and is transcriptionally repressed. • Multiple factors affect thiamine synthesis, availability and uptake for wine yeast. • Thiamine availability impacts fermentation kinetics and wine's sensory properties.
酒精发酵是酿酒过程中的关键步骤，在此过程中酵母将糖分转化为酒精，并产生或生物转化多种风味化合物。在这种情况下，营养物质是支持酵母生长并最终确保完全发酵以及优化风味化合物而非异味化合物产量的必需化合物。特别是，维生素硫胺素不仅对参与各种代谢途径（包括那些导致产生与葡萄酒相关的风味化合物的途径）的几种酶起着必需的辅助因子作用，还通过硫胺素依赖性应激保护功能帮助酵母存活。大多数酵母物种既能将外源硫胺素吸收到细胞中，又能从头合成硫胺素。然而，硫胺素积累的机制和水平取决于几个因素。本综述深入概述了模式酵母酿酒酵母中硫胺素的利用和代谢，以及关于（1）硫胺素的细胞内功能，（2）硫胺素摄取与合成之间的平衡及其调节，（3）影响硫胺素可用性和利用的众多因素的现有知识。对于后者，特别强调了葡萄酒发酵过程中出现的条件。讨论了葡萄汁中硫胺素浓度对于确保成功发酵的充足性，以及硫胺素浓度对发酵动力学和葡萄酒感官特性的影响。这些知识可作为优化硫胺素浓度以实现酵母最佳工业应用的资源。要点：• 硫胺素摄取优于生物合成且受到转录抑制。•多种因素影响葡萄酒酵母的硫胺素合成、可用性和摄取。•硫胺素可用性影响发酵动力学和葡萄酒的感官特性。
