IBB, Institute of Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
Biotechnol Biofuels. 2011 Dec 9;4(1):57. doi: 10.1186/1754-6834-4-57.
The optimization of industrial bioethanol production will depend on the rational design and manipulation of industrial strains to improve their robustness against the many stress factors affecting their performance during very high gravity (VHG) or lignocellulosic fermentations. In this study, a set of Saccharomyces cerevisiae genes found, through genome-wide screenings, to confer resistance to the simultaneous presence of different relevant stresses were identified as required for maximal fermentation performance under industrial conditions.
Chemogenomics data were used to identify eight genes whose expression confers simultaneous resistance to high concentrations of glucose, acetic acid and ethanol, chemical stresses relevant for VHG fermentations; and eleven genes conferring simultaneous resistance to stresses relevant during lignocellulosic fermentations. These eleven genes were identified based on two different sets: one with five genes granting simultaneous resistance to ethanol, acetic acid and furfural, and the other with six genes providing simultaneous resistance to ethanol, acetic acid and vanillin. The expression of Bud31 and Hpr1 was found to lead to the increase of both ethanol yield and fermentation rate, while Pho85, Vrp1 and Ygl024w expression is required for maximal ethanol production in VHG fermentations. Five genes, Erg2, Prs3, Rav1, Rpb4 and Vma8, were found to contribute to the maintenance of cell viability in wheat straw hydrolysate and/or the maximal fermentation rate of this substrate.
The identified genes stand as preferential targets for genetic engineering manipulation in order to generate more robust industrial strains, able to cope with the most significant fermentation stresses and, thus, to increase ethanol production rate and final ethanol titers.
工业生物乙醇生产的优化将取决于对工业菌株的合理设计和操作，以提高其在超高浓度（VHG）或木质纤维素发酵过程中应对影响其性能的多种压力因素的稳健性。在这项研究中，通过全基因组筛选发现了一组赋予酵母细胞对不同相关压力同时存在的抗性的酿酒酵母基因，这些基因被认为是在工业条件下实现最大发酵性能所必需的。
化学生态组学数据用于鉴定八个基因，其表达赋予同时抵抗高浓度葡萄糖、乙酸和乙醇的能力，这些是 VHG 发酵中相关的化学压力；以及十一个同时赋予木质纤维素发酵中相关压力抗性的基因。这十一个基因是基于两套不同的数据集鉴定出来的：一套包括五个基因，赋予同时抵抗乙醇、乙酸和糠醛的能力；另一套包括六个基因，赋予同时抵抗乙醇、乙酸和香草醛的能力。发现 Bud31 和 Hpr1 的表达导致乙醇产率和发酵速率的增加，而 Pho85、Vrp1 和 Ygl024w 的表达是 VHG 发酵中最大乙醇产量所必需的。发现五个基因，即 Erg2、Prs3、Rav1、Rpb4 和 Vma8，有助于维持小麦秸秆水解物中的细胞活力和/或该底物的最大发酵速率。
鉴定出的基因是遗传工程操作的首选目标，以生成更稳健的工业菌株，能够应对最显著的发酵压力，从而提高乙醇产率和最终乙醇浓度。
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