Muller Gabriela, de Godoy Victor R, Dário Marcelo G, Duval Eduarda H, Alves-Jr Sergio L, Bücker Augusto, Rosa Carlos A, Dunn Barbara, Sherlock Gavin, Stambuk Boris U
Department of Biochemistry, Federal University of Santa Catarina, Florianópolis, Santa Catarina 88040-900, Brazil.
Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil.
J Fungi (Basel). 2023 Jul 29;9(8):803. doi: 10.3390/jof9080803.
In Brazil, sucrose-rich broths (cane juice and/or molasses) are used to produce billions of liters of both fuel ethanol and per year using selected industrial strains. Considering the important role of feedstock (sugar) prices in the overall process economics, to improve sucrose fermentation the genetic characteristics of a group of eight fuel-ethanol and five industrial yeasts that tend to dominate the fermentors during the production season were determined by array comparative genomic hybridization. The widespread presence of genes encoding invertase at multiple telomeres has been shown to be a common feature of both baker's and distillers' yeast strains, and is postulated to be an adaptation to sucrose-rich broths. Our results show that only two strains (one fuel-ethanol and one yeast) have amplification of genes encoding invertase, with high specific activity. The other industrial yeast strains had a single locus () in their genome, with different patterns of invertase activity. These results indicate that invertase activity probably does not limit sucrose fermentation during fuel-ethanol and production by these industrial strains. Using this knowledge, we changed the mode of sucrose metabolism of an industrial strain by avoiding extracellular invertase activity, overexpressing the intracellular invertase, and increasing its transport through the permease. This approach allowed the direct consumption of the disaccharide by the cells, without releasing glucose or fructose into the medium, and a 11% higher ethanol production from sucrose by the modified industrial yeast, when compared to its parental strain.
在巴西，每年使用选定的工业菌株，利用富含蔗糖的肉汤（甘蔗汁和/或糖蜜）生产数十亿升燃料乙醇和[此处原文缺失部分内容]。考虑到原料（糖）价格在整个工艺经济中的重要作用，为了改善蔗糖发酵，通过阵列比较基因组杂交确定了一组在生产季节往往在发酵罐中占主导地位的8种燃料乙醇酵母和5种工业酵母的遗传特征。已证明在多个端粒上广泛存在编码转化酶的基因是面包酵母和酿酒酵母菌株的共同特征，并推测这是对富含蔗糖肉汤的一种适应。我们的结果表明，只有两种菌株（一种燃料乙醇酵母和一种[此处原文缺失部分内容]酵母）具有编码转化酶的基因扩增，且具有高比活性。其他工业酵母菌株在其基因组中有一个单一基因座（[此处原文缺失部分内容]），具有不同的转化酶活性模式。这些结果表明，转化酶活性可能并不限制这些工业菌株在燃料乙醇和[此处原文缺失部分内容]生产过程中的蔗糖发酵。利用这一知识，我们通过避免细胞外转化酶活性、过表达细胞内转化酶并增加其通过[此处原文缺失部分内容]通透酶的转运，改变了一种工业菌株的蔗糖代谢模式。这种方法使细胞能够直接消耗二糖，而不将葡萄糖或果糖释放到培养基中，与亲本菌株相比，改良后的工业酵母从蔗糖中生产的乙醇产量提高了11%。
