葡萄酒酒精发酵的微生物多样性不限于酵母菌株的存在和活性。一些非酵母属物种已被描述为发酵微生物群的一部分,特别是在葡萄酒发酵的初始步骤中发现的。这些物种可能从葡萄酒变质到风味质量增强都起作用。从大量的葡萄酒发酵(429个葡萄酒样品),通过ITS-扩增子测序进行分析,以定义它们的分枝杆菌群,检测到2种非常规酵母菌种(Nakazawaeaishiwadae和长孢子酵母),在非常有限的样品数量中,但相对丰度水平很高。分离出每种物种的一种菌株,并在这项工作中表征了它们的技术和环境潜力。与酿酒酵母VinifermRevelacion葡萄酒菌株相比,研究的N.ishiwadaeBMK17.1和L.elongisporusBMK12.5菌株显示,正如预期的那样,在高乙醇浓度下的耐受性和生长适应性较低。然而,N.ishiwadaeBMK17.1也能够在15%的乙醇下生长,而L.elongisporusBMK12.5在10%时达到,在后一种情况下,在这个水平上,效率比酿酒酵母略高。与大多数非酵母菌相反,这些物种能够在高剂量的焦亚硫酸钾存在下生长,在两种情况下都达到比酿酒酵母更高的效率。清楚地观察到长孢子乳杆菌BMK12.5对高pH值的显著亲和力。在微发酵试验中研究了它们的发酵动力学和最终的化学分析特性,用合成葡萄必须。L.elongisporusBMK12.5能够完成,在单次接种中,19天后的糖发酵,但是,N.ishiwadaeBMK17.1此时留下约80g/L糖。共同接种测定(在1:100比例的酿酒酵母:非酵母菌株中)完成的糖消耗具有与酿酒酵母单次接种相似的动力学,在长孢菌BMK12.5共同接种的情况下,使用N.ishiwadaeBMK17.1时,动力学较低。显著的苹果酸消耗和低乙酸产量与长孢菌BMK12.5发酵有关,以及3-甲基-1-丁醇和2-苯基乙醇的高产量,和大量蛋白质释放到葡萄酒中。N.ishiwadaeBMK17.1,虽然无法完成发酵本身,显示低聚糖和挥发性化合物如异丁醇或异丁酸的高产量。这项工作报告,第一次,与非常规酵母属Lodderomyces和Nakazawaea有关的两个菌株的发生和内生潜力。
The microbial diversity of wine alcoholic fermentation is not restricted to the presence and activity of Saccharomyces yeast strains. Some non-Saccharomyces species have been described as part of the fermentative microbiota, specially found in the initial steps of wine fermentations. These species may play roles from wine spoilage to flavor quality enhancement. From a large number of wine fermentations (429 wine samples), analyzed by ITS-amplicon sequencing to define their mycobiome, 2 non-conventional yeast species (Nakazawaea ishiwadae and Lodderomyces elongisporus) were detected, in a very limited number of samples but in significant levels of relative abundance. One strain of each species was isolated and their technological and enological potential have been characterized in this work. Compared with the Saccharomyces cerevisiae Viniferm Revelacion wine strain, the studied N. ishiwadae BMK17.1 and L. elongisporus BMK12.5 strains showed, as expected, a lower tolerance and growth fitness in high ethanol concentrations. However, N. ishiwadae BMK17.1 was able to grow also at 15% ethanol and L. elongisporus BMK12.5 at 10% reaching, in the latter case, slightly higher efficiency rates than S. cerevisiae at this level. Contrary to most non-Saccharomyces yeasts, these species were able to growth in presence of high doses of potassium-metabisulfite, reaching in both cases higher efficiency rates than S. cerevisiae. A notable affinity of L. elongisporus BMK12.5 for high pH values was clearly observed. Their fermentation kinetics and the final chemical-analytical characterization were studied in micro-fermentation assays, using synthetic grape must. L. elongisporus BMK12.5 was able to complete, in single inoculation, the sugar fermentation after 19 days, but, N. ishiwadae BMK17.1 left about 80 g/L sugars at this time. Co-inoculation assays (in a 1:100 proportion of S. cerevisiae:non-Saccharomyces strains) finished sugar consumption with similar kinetics than the S. cerevisiae single inoculation, in the case of L. elongisporus BMK12.5 co-inoculation, and with lower kinetics when using N. ishiwadae BMK17.1. A remarkable malic acid consumption and a low acetic acid production was associated with L. elongisporus BMK12.5 fermentations, together with a high production of 3-methyl-1-butanol and 2-phenylethanol, and the release of high amounts of proteins into the wines. N. ishiwadae BMK17.1, although unable to finish the fermentation itself, showed a high production of oligosaccharides and volatile compounds such as isobutanol or isobutyric acid. This work reports, for the first time, the occurrence and enological potential of two strains pertaining to the non-conventional yeast genera Lodderomyces and Nakazawaea.