Aafke C A van Aalst, Ellen H Geraats, Mickel L A Jansen, Robert Mans, Jack T Pronk
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For optimal performance in industrial settings, yeast strains should ideally first fully convert acetate and, subsequently, continue low-glycerol fermentation via the PRK-RuBisCO pathway. However, anaerobic batch cultures of a strain carrying both pathways showed inferior acetate reduction relative to a strain expressing only the A-ALD pathway. Complete A-ALD-mediated acetate reduction by a dual-pathway strain, grown anaerobically on 50 g L-1 glucose and 5 mmol L-1 acetate, was achieved upon reducing PRK abundance by a C-terminal extension of its amino acid sequence. Yields of glycerol and ethanol on glucose were 55% lower and 6% higher, respectively, than those of a nonengineered reference strain. The negative impact of the PRK-RuBisCO pathway on acetate reduction was attributed to sensitivity of the reversible A-ALD reaction to intracellular acetaldehyde concentrations.</p>","PeriodicalId":12290,"journal":{"name":"FEMS yeast research","volume":" ","pages":""},"PeriodicalIF":2.4000,"publicationDate":"2023-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10647013/pdf/","citationCount":"0","resultStr":"{\"title\":\"Optimizing the balance between heterologous acetate- and CO2-reduction pathways in anaerobic cultures of Saccharomyces cerevisiae strains engineered for low-glycerol production.\",\"authors\":\"Aafke C A van Aalst, Ellen H Geraats, Mickel L A Jansen, Robert Mans, Jack T Pronk\",\"doi\":\"10.1093/femsyr/foad048\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>In anaerobic Saccharomyces cerevisiae cultures, NADH (reduced form of nicotinamide adenine dinucleotide)-cofactor balancing by glycerol formation constrains ethanol yields. 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引用次数: 0
摘要
在厌氧酿酒酵母培养物中,通过甘油形成的NADH辅因子平衡限制了乙醇产量。基于异源乙酰化乙醛脱氢酶(A-ALD)的乙酸盐-乙醇还原途径的引入可以取代甘油作为“氧化还原库”的形成,并提高含乙酸盐介质中的乙醇产量。然而,第一代生物乙醇生产原料中的乙酸盐浓度不足以完全取代甘油的形成。另一种甘油还原策略通过引入磷酸二激酶(PRK)和核酮糖-1,5-二磷酸羧化酶/加氧酶(RuBisCO)绕过糖酵解中的氧化反应。为了在工业环境中获得最佳性能,理想情况下,酵母菌株应首先完全转化乙酸盐,然后通过PRK-RuBisCO途径继续低甘油发酵。然而,与仅表达a-ALD途径的菌株相比,携带两种途径的菌株的厌氧分批培养显示出较差的乙酸盐还原。在50 g L-1葡萄糖和5 mmol L-1乙酸盐上厌氧生长的双途径菌株通过其氨基酸序列的C末端延伸降低PRK丰度后,实现了A-ALD介导的乙酸盐的完全还原。甘油和乙醇对葡萄糖的产量分别比非工程参考菌株低55%和高6%。PRK-RuBisCO途径对乙酸盐还原的负面影响归因于可逆A-ALD反应对细胞内乙醛浓度的敏感性。
Optimizing the balance between heterologous acetate- and CO2-reduction pathways in anaerobic cultures of Saccharomyces cerevisiae strains engineered for low-glycerol production.
In anaerobic Saccharomyces cerevisiae cultures, NADH (reduced form of nicotinamide adenine dinucleotide)-cofactor balancing by glycerol formation constrains ethanol yields. Introduction of an acetate-to-ethanol reduction pathway based on heterologous acetylating acetaldehyde dehydrogenase (A-ALD) can replace glycerol formation as 'redox-sink' and improve ethanol yields in acetate-containing media. Acetate concentrations in feedstock for first-generation bioethanol production are, however, insufficient to completely replace glycerol formation. An alternative glycerol-reduction strategy bypasses the oxidative reaction in glycolysis by introducing phosphoribulokinase (PRK) and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). For optimal performance in industrial settings, yeast strains should ideally first fully convert acetate and, subsequently, continue low-glycerol fermentation via the PRK-RuBisCO pathway. However, anaerobic batch cultures of a strain carrying both pathways showed inferior acetate reduction relative to a strain expressing only the A-ALD pathway. Complete A-ALD-mediated acetate reduction by a dual-pathway strain, grown anaerobically on 50 g L-1 glucose and 5 mmol L-1 acetate, was achieved upon reducing PRK abundance by a C-terminal extension of its amino acid sequence. Yields of glycerol and ethanol on glucose were 55% lower and 6% higher, respectively, than those of a nonengineered reference strain. The negative impact of the PRK-RuBisCO pathway on acetate reduction was attributed to sensitivity of the reversible A-ALD reaction to intracellular acetaldehyde concentrations.
期刊介绍:
FEMS Yeast Research offers efficient publication of high-quality original Research Articles, Mini-reviews, Letters to the Editor, Perspectives and Commentaries that express current opinions. The journal will select for publication only those manuscripts deemed to be of major relevance to the field and generally will not consider articles that are largely descriptive without insights on underlying mechanism or biology. Submissions on any yeast species are welcome provided they report results within the scope outlined below and are of significance to the yeast field.