Alves-Araújo C, Pacheco A, Almeida M J, Spencer-Martins I, Leão C, Sousa M J
Center of Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
Centro de Recursos Microbiológicos (CREM), Biotechnology Unit, Faculty of Sciences and Technology, New University of Lisbon, 2829-516 Caparica, Portugal.
Microbiology (Reading). 2007 Mar;153(Pt 3):898-904. doi: 10.1099/mic.0.2006/003475-0.
The highly osmo- and cryotolerant yeast species Torulaspora delbrueckii is an important case study among the non-Saccharomyces yeast species. The strain T. delbrueckii PYCC 5321, isolated from traditional corn and rye bread dough in northern Portugal, is considered particularly interesting for the baking industry. This paper reports the sugar utilization patterns of this strain, using media with glucose, maltose and sucrose, alone or in mixtures. Kinetics of growth, biomass and ethanol yields, fermentation and respiration rates, hydrolase activities and sugar uptake rates were used to infer the potential applied relevance of this yeast in comparison to a conventional baker's strain of Saccharomyces cerevisiae. The results showed that both maltase and maltose transport in T. delbrueckii were subject to glucose repression and maltose induction, whereas invertase was subject to glucose control but not dependent on sucrose induction. A comparative analysis of specific sugar consumption rates and transport capacities suggests that the transport step limits both glucose and maltose metabolism. Specific rates of CO(2) production and O(2) consumption showed a significantly higher contribution of respiration to the overall metabolism in T. delbrueckii than in S. cerevisiae. This was reflected in the biomass yields from batch cultures and could represent an asset for the large-scale production of the former species. This work contributes to a better understanding of the physiology of a non-conventional yeast species, with a view to the full exploitation of T. delbrueckii by the baking industry.
高度耐高渗和耐低温的酵母菌种德尔布有孢圆酵母是非常规酵母菌种中的一个重要案例研究对象。从葡萄牙北部传统玉米和黑麦面包面团中分离出的德尔布有孢圆酵母菌株PYCC 5321，被认为对烘焙行业特别有意义。本文报道了该菌株在单独使用葡萄糖、麦芽糖和蔗糖或它们的混合物作为培养基时的糖利用模式。通过生长动力学、生物量和乙醇产量、发酵和呼吸速率、水解酶活性以及糖摄取速率，来推断该酵母与传统酿酒酵母烘焙菌株相比潜在的应用相关性。结果表明，德尔布有孢圆酵母中的麦芽糖酶和麦芽糖转运均受到葡萄糖阻遏和麦芽糖诱导，而蔗糖酶受到葡萄糖调控但不依赖蔗糖诱导。对特定糖消耗速率和转运能力的比较分析表明，转运步骤限制了葡萄糖和麦芽糖的代谢。二氧化碳产生和氧气消耗的特定速率表明，与酿酒酵母相比，德尔布有孢圆酵母中呼吸作用对整体代谢的贡献显著更高。这在分批培养的生物量产量中得到体现，并且可能是大规模生产该酵母菌种的一项优势。这项工作有助于更好地理解非常规酵母菌种的生理学特性，以期烘焙行业能充分利用德尔布有孢圆酵母。
