The focus of this thesis was to examine the relatedness of industrially available active dry yeast (ADY) and to examine the method of "yeast propagation" used for the production of fuel ethanol. A new term, metabolic acclimatization; abbreviated as MAcc, was proposed to describe this process. Nutritional improvements and how this affects "yeast propagation" and subsequent fermentations were also investigated.; Seven industrial ADY obtained from different suppliers were subjected to traditional screening methods (viability, contaminant levels, fermentation rates, generation times, size analysis, optimal fermentation temperature, fermentative performance in normal and very high gravity corn mashes). They were also compared using molecular techniques (karyotyping and mitochondrial DNA analysis). Results of the traditional screening techniques allowed each ADY to be characterized and compared. For example, it was observed that of the seven samples, one had a low viability compared to the expected norm of ∼2.2 x 110 cells/g. Two of the samples were observed to have high levels of contaminants (0.1% anaerobic bacteria) suggesting that these samples should not be used due to the risk of bacterial contamination and subsequent loss of ethanol yield during fermentation. The differences seen in activity were probably due to manufacturing processes and drying techniques. Molecular examination of the seven ADY samples revealed four distinct karyotypic patterns. Mitochondrial DNA (mtDNA) analysis confirmed the karyotypic results (with the exception of one ADY) and revealed that only three distinct patterns could be seen. These results demonstrated that of the seven ADY, only one sample was unique as the other six (in two Groups) were found to share karyotypic and mtDNA patterns. This would suggest that most of the industrially available ADY share their lineage with other marketed yeasts, and as few as three yeasts may be available to industry but produced by more than one company. (Abstract shortened by UMI.)
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机译：本论文的重点是研究工业上可用的活性干酵母（ADY）的相关性，并研究用于生产燃料乙醇的“酵母菌繁殖”方法。新的术语，新陈代谢适应；有人提出将其缩写为MAcc来描述此过程。还研究了营养改善及其对“酵母繁殖”和后续发酵的影响。从不同供应商处获得的七个工业ADY受传统筛选方法（可行性，污染物水平，发酵速率，生成时间，尺寸分析，最佳发酵温度，正常和极高重力玉米的发酵性能）的筛选。还使用分子技术（核型分析和线粒体DNA分析）对它们进行了比较。传统筛选技术的结果可以对每个ADY进行表征和比较。例如，据观察，在七个样品中，与预期的约2.2 x 110细胞/ g相比，一个样品的活力较低。观察到其中两个样品的污染物含量高（0.1％厌氧细菌），这表明不应使用这些样品，因为存在细菌污染的风险，并且在发酵过程中会损失乙醇产量。活性差异可能是由于制造工艺和干燥技术所致。七个ADY样品的分子检查显示了四个不同的核型。线粒体DNA（mtDNA）分析证实了核型结果（一个ADY除外），并揭示只能看到三种不同的模式。这些结果表明，在七个ADY中，只有一个样本是唯一的，因为发现其他六个（在两个组中）具有核型和mtDNA模式。这表明大多数工业上可获得的ADY与其他市场上的酵母菌共享其血统，并且可能只有三个以上的酵母菌可用于工业生产，但由多家公司生产。 （摘要由UMI缩短。）
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