Institute for Wine Biotechnology, Department of Viticulture and Oenology, Stellenbosch University, Stellenbosch, Western Cape, South Africa.
Centre for Bioinformatics and Computational Biology, Stellenbosch University, Stellenbosch, Western Cape, South Africa.
BMC Genomics. 2019 Feb 18;20(1):145. doi: 10.1186/s12864-019-5511-x.
In wine fermentation starter cultures, the blending of non-Saccharomyces yeast with Saccharomyces cerevisiae to improve the complexity of wine has become common practice, but data regarding the impact of co-cultivation on yeast physiology and on genetic and metabolic regulation remain limited. Here we describe a transcriptomic analysis of mixed fermentations of Saccharomyces cerevisiae and Lachancea thermotolerans. The fermentations were carried out in carefully controlled environmental conditions in a bioreactor to reduce transcriptomic responses that would be due to factors other than the presence of the second species.
The transcriptomic data revealed that both yeast species showed a clear response to the presence of the other. Affected genes primarily belonged to two groups: genes whose expression can be linked to the competition for certain trace elements such as copper and iron, as well as genes required for cell wall structure and integrity. Furthermore, the data revealed divergent transcriptional responses with regard to carbon metabolism in response to anoxic conditions.
The results suggest that the mixed fermentation created a more competitive and stressful environment for the two species than single strain fermentations independently from total biomass, i.e. competition between cells of the same species is less stressful, or may present a different set of challenges, than interspecies competition. The changes in cell wall and adhesion properties encoding genes suggest that the adjustment of physical contact between cells may play a direct role in the response to the presence of competing species.
在葡萄酒发酵的起始培养物中，混合使用非酿酒酵母和酿酒酵母以提高葡萄酒的复杂性已成为常见做法，但关于共培养对酵母生理学以及遗传和代谢调控的影响的数据仍然有限。在这里，我们描述了酿酒酵母和耐热酒香酵母混合发酵的转录组分析。在生物反应器中，在精心控制的环境条件下进行发酵，以减少除第二种物种存在以外的因素引起的转录组响应。
转录组数据显示，两种酵母都对另一种酵母的存在表现出明显的反应。受影响的基因主要属于两组：其表达可以与对某些痕量元素（如铜和铁）的竞争相关的基因，以及细胞壁结构和完整性所需的基因。此外，数据还揭示了在缺氧条件下，碳代谢的转录响应存在差异。
结果表明，与独立的单菌株发酵相比，混合发酵在总生物量之外为两种菌株创造了一个更具竞争性和压力性的环境，即同种细胞之间的竞争压力较小，或者可能面临不同的挑战，而不是种间竞争。细胞壁和黏附特性编码基因的变化表明，细胞之间物理接触的调整可能直接参与了对竞争物种存在的反应。
