Uppsala BioCentre, Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Yeast. 2012 Jul;29(7):265-74. doi: 10.1002/yea.2904. Epub 2012 Jun 2.
The effect of glucose and oxygen limitation on the growth and fermentation performances of Dekkera bruxellensis was investigated in order to understand which factors favour its propagation in ethanol or wine plants. Although D. bruxellensis has been described as a facultative anaerobe, no growth was observed in mineral medium under complete anaerobiosis while growth was retarded under severe oxygen limitation. In a continuous culture with no gas inflow, glucose was not completely consumed, most probably due to oxygen limitation. When an air/nitrogen mixture (O(2)-content ca. 5%) was sparged to the culture, growth became glucose-limited. In co-cultivations with Saccharomyces cerevisiae, ethanol yields/g consumed sugar were not affected by the co-cultures as compared to the pure cultures. However, different population responses were observed in both systems. In oxygen-limited cultivation, glucose was depleted within 24 h after challenging with S. cerevisiae and both yeast populations were maintained at a stable level. In contrast, the S. cerevisiae population constantly decreased to about 1% of its initial cell number in the sparged glucose-limited fermentation, whereas the D. bruxellensis population remained constant. To identify the requirements of D. bruxellensis for anaerobic growth, the yeast was cultivated in several nitrogen sources and with the addition of amino acids. Yeast extract and most of the supplied amino acids supported anaerobic growth, which points towards a higher nutrient demand for D. bruxellensis compared to S. cerevisiae in anaerobic conditions.
为了了解哪些因素有利于其在乙醇或葡萄酒厂中繁殖，研究了葡萄糖和氧气限制对德克氏酵母生长和发酵性能的影响。尽管德克氏酵母被描述为兼性厌氧菌，但在完全无氧的矿物培养基中没有观察到生长，而在严重的氧气限制下生长受到抑制。在没有气体流入的连续培养中，葡萄糖没有完全消耗，这很可能是由于氧气限制。当向培养物中注入空气/氮气混合物（O 2 含量约为 5%）时，生长成为葡萄糖限制。在与酿酒酵母的共培养中，与纯培养物相比，乙醇产率/消耗糖不受共培养物的影响。然而，在这两个系统中观察到了不同的种群反应。在氧气限制培养中，在与酿酒酵母接触后 24 小时内耗尽葡萄糖，并且两个酵母种群都保持在稳定水平。相比之下，在通气的葡萄糖限制发酵中，酿酒酵母种群不断减少到初始细胞数的约 1%，而德克氏酵母种群保持不变。为了确定德克氏酵母对厌氧生长的要求，将酵母在几种氮源和添加氨基酸的情况下进行培养。酵母提取物和大多数供应的氨基酸支持厌氧生长，这表明与酿酒酵母相比，德克氏酵母在厌氧条件下对营养物质的需求更高。
