Univ. Bourgogne Franche-Comté, Institut Agro Dijon, PAM UMR A 02.102, Institut Universitaire de La Vigne et du Vin - Jules Guyot, Dijon, France.
Ecology and Evolution of Antibiotic Resistance Unit, Institut Pasteur, Université Paris-Cité, CNRS UMR6047, Paris, France.
Res Microbiol. 2023 Jun;174(5):104048. doi: 10.1016/j.resmic.2023.104048. Epub 2023 Mar 7.
Oenococcus oeni is the main lactic acid bacterium associated with malolactic fermentation (MLF) of wines. MLF plays an important role in determining the final quality of wines. Nevertheless, due to the stressful conditions inherent to wine and especially acidity, MLF may be delayed. This study aimed to explore by adaptive evolution improvements in the acid tolerance of starters but also to gain a better understanding of the mechanisms involved in adaptation toward acidity. Four independent populations of the O. oeni ATCC BAA-1163 strain were propagated (approximately 560 generations) in a temporally varying environment, consisting in a gradual pH decrease from pH 5.3 to pH 2.9. Whole genome sequence comparison of these populations revealed that more than 45% of the substituted mutations occurred in only five loci for the evolved populations. One of these five fixed mutations affects mae, the first gene of the citrate operon. When grown in an acidic medium supplemented with citrate, a significantly higher bacterial biomass was produced with the evolved populations compared to the parental strain. Furthermore, the evolved populations slowed down their citrate consumption at low pH without impacting malolactic performance.
酒香酵母是与葡萄酒中苹果酸-乳酸发酵（MLF）相关的主要乳酸菌。MLF 在决定葡萄酒的最终质量方面起着重要作用。然而，由于葡萄酒固有的压力条件，特别是酸度，MLF 可能会延迟。本研究旨在通过适应性进化来提高起始培养物的耐酸性，同时更好地了解适应酸度的相关机制。将 O. oeni ATCC BAA-1163 菌株的四个独立种群在时间变化的环境中繁殖（约 560 代），该环境的 pH 值逐渐从 5.3 下降到 2.9。对这些种群的全基因组序列比较表明，进化种群中超过 45%的取代突变发生在仅五个基因座。这五个固定突变之一影响柠檬酸操纵子的第一个基因 mae。与原始菌株相比，在添加柠檬酸的酸性培养基中生长时，进化种群产生了明显更高的细菌生物量。此外，进化种群在低 pH 值下减缓了柠檬酸的消耗，而不会影响苹果酸-乳酸发酵性能。
