Vitamin B₁, also known as thiamine, is an important vitamin that, besides its role in human health, is converted to meat aromas upon exposure to high temperatures. Therefore, it is relevant for the production of vegan meat-like flavours. In this study, we investigated 48 Saccharomyces cerevisiae strains for their thiamine production capacity by measuring the intracellular and extracellular vitamins produced in the thiamine-free minimal medium after 72 h of growth. We found approximately an 8.2-fold difference in overall thiamine yield between the highest and lowest-producing strains. While the highest thiamine yield was 254.6 nmol/L, the highest thiamine-specific productivity was 160.9 nmol/g DW. To assess whether extracellular thiamine was due to leakage caused by cell damage, we monitored membrane permeabilization using propidium iodide (PI) staining and flow cytometry. We found a good correlation between the percentage of extracellular thiamine and PI-stained cells (Spearman's ρ = 0.85). Finally, we compared S. cerevisiae CEN.PK113-7D (wild type [WT]) to three strains evolved in a thiamine-free medium for their thiamine production capacity. On average, we saw an increase in the amount of thiamine produced. One of the evolved strains had a 49% increase in intracellular thiamine-specific productivity and a biomass increase of 20% compared with the WT. This led to a total increase in thiamine yield of 60% in this strain, reaching 208 nmol/L. This study demonstrated that it is possible to achieve thiamine overproduction in S. cerevisiae via strain selection and adaptive laboratory evolution.

中文翻译：

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酿酒酵母硫胺素生产能力的菌株多样性

维生素 B ₁，也称为硫胺素，是一种重要的维生素，除了对人体健康有重要作用外，在高温下会转化为肉香味。因此，它与纯素肉风味的生产相关。在这项研究中，我们通过测量生长 72 小时后在不含硫胺素的基本培养基中产生的细胞内和细胞外维生素，研究了 48 种酿酒酵母菌株的硫胺素生产能力。我们发现硫胺素产量最高和最低的菌株之间大约有 8.2 倍的差异。最高硫胺素产率为 254.6 nmol/L，最高硫胺素比生产率为 160.9 nmol/g DW。为了评估细胞外硫胺素是否是由于细胞损伤引起的渗漏，我们使用碘化丙啶 (PI) 染色和流式细胞术监测膜透化。我们发现细胞外硫胺素和 PI 染色细胞的百分比之间存在良好的相关性（Spearman's ρ  = 0.85）。最后，我们将酿酒酵母CEN.PK113-7D（野生型 [WT]）与在不含硫胺素的培养基中进化的三种菌株的硫胺素生产能力进行了比较。平均而言，我们发现硫胺素的产生量有所增加。与野生型相比，其中一种进化菌株的细胞内硫胺素特异性生产力增加了 49%，生物量增加了 20%。这使得该菌株的硫胺素产量总共增加了 60%，达到 208 nmol/L。这项研究表明，通过菌株选择和适应性实验室进化，可以在酿酒酵母中实现硫胺素过量生产。