The two most commonly used wine microorganisms, Saccharomyces cerevisiae yeast and Oenococcus oeni bacteria, are responsible for completion of alcoholic and malolactic fermentation (MLF), respectively. For successful co-inoculation, S. cerevisiae and O. oeni must be able to complete fermentation, however, this relies on compatibility between yeast and bacterial strains. For the first time, Quantitative Trait Loci (QTL) analysis was used to elucidate whether S. cerevisiae genetic makeup can play a role in the ability of O. oeni to complete MLF. Assessment of 67 progeny of an S. cerevisiae SBxGN cross, co-inoculated with a single O. oeni strain, SB3, revealed a major QTL linked to MLF completion by O. oeni. This QTL encompassed a well-known translocation, XV-t-XVI, that results in increased SSU1 expression and is functionally linked with numerous phenotypes including lag phase duration and sulfite export and production. A reciprocal hemizygosity assay was performed to elucidate the effect of the gene SSU1 in the SBxGN background. Our results instead revealed a strong effect of SSU1 haploinsufficiency on O. oeni′s ability to complete malolactic fermentation during co-inoculation, and paves the way for the implementation of QTL mapping projects for deciphering the genetic bases of microbial interactions.

中文翻译：

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QTL作图：一种用于研究葡萄酒中酵母与细菌相互作用的遗传确定性的创新方法

酒中最常用的两种微生物是酿酒酵母酵母和oenococcus oeni细菌，分别负责酒精和苹果酸发酵（MLF）。为了成功地共接种，酿酒酵母和O. oeni必须能够完成发酵，但是，这取决于酵母菌和细菌菌株之间的相容性。第一次，定量性状位点（QTL）分析被用来阐明酿酒酵母的基因组成是否可以在O. oeni完成MLF的能力中起作用。与单个O. oeni一起接种的酿酒酵母SBxGN杂交的67个后代的评估菌株SB3揭示了一个主要的QTL，与O. oeni的MLF完成有关。该QTL包含一个众所周知的易位XV-t-XVI，它导致SSU1表达增加，并与许多表型（包括滞后期持续时间和亚硫酸盐的输出和产生）在功能上相关联。进行了相互半合子测定以阐明基因SSU1在SBxGN背景中的作用。我们的结果反而显示了SSU1单倍剂量不足对O. oeni在共接种过程中完成苹果乳酸发酵的能力的强大影响，并为实施QTL作图项目以破译微生物相互作用的遗传基础铺平了道路。