Freeze tolerance of the yeastTorulaspora delbrueckii: cellular and biochemical basis

Abstract

The freeze stress responses to prolonged storage at -20 degrees C in Torulaspora delbrueckii PYCC5323 were investigated. In this yeast, no loss of cell viability was observed for at least 120 days during freezing at -20 degrees C, whereas a loss of 80% was observed in a commercial baker's yeast after 15 days. In the former strain, freeze resistance was dependent on an adaptation process. The primary cell target of freeze stress was the plasma membrane, preservation of its integrity being related with a lower increase of lipid peroxidation and with a higher resistance to H(2)O(2), but not with the intracellular trehalose concentration.

The Emerging Role of the Yeast Torulaspora delbrueckii in Bread and Wine Production: Using Genetic Manipulation to Study Molecular Basis of Physiological Responses

“…The biotechnological interest in Torulaspora delbrueckii has increased in recent years due to its particularly high freezing and osmotic tolerance (4,5,46). These features made this yeast species a candidate of potential value for the baking industry.…”

“…Or is this yeast more comparable to S. cerevisiae as is suggested by their similar sugar utilizations patterns (7)? Evidently, it would be important to continue the characterization of T. delbrueckii strains, as their biotechnological potential has already been established (5,7,46). It is clear that answers to these questions may only arise from future studies.…”

“…Issatchenkia orientalis, Pichia membranaefaciens, and Torulaspora delbrueckii were the most abundant non-Saccharomyces species present in homemade corn and rye bread dough (6,45). Among them, the biotechnological interest in T. delbrueckii has increased in recent years due to its particularly high freezing and osmotic tolerance (4,5,46). Thus, some T. delbrueckii strains are commercialized in Japan for regular (5% sucrose) frozen dough applications (47).…”

“…Two strains of interest for the bread industry have been isolated from traditional corn and rye bread dough from the North of Portugal. Both strains are potentially interesting to use in frozen dough technology due to their particularly high resistance to osmotic and freeze stress (4)(5)(6), and have been the subject of detailed studies. These studies focused on the characterization of traits that are relevant for a potential industrial application, such as growth rate and biomass yield on sucrose, maltose fermentative capacity, and patterns of sugar utilization and regulation when mixtures of different sugars are present (7).…”

Isolation and characterization of the carbon catabolite‐derepressing protein kinase Snf1 from the stress tolerant yeast Torulaspora delbrueckii

“…However, the characterization of the SNF1-AMPK pathway in nonconventional stress-resistant yeasts, like Zygosaccharomyces rouxii, Debaryomyces hansenii or Torulaspora delbrueckii, has received little attention. T. delbrueckii, a facultative fermentative species, has been recognized as the most promising alternative to industrial strains of S. cerevisiae (Hernández-López et al, 2003;Alves-Araújo et al, 2007), due to its high resistance to several types of stresses (Almeida and Pais, 1996;Hernández-López et al, 2003;Alves-Araújo et al, 2004). Genes like TdHOG1 (Hernández-López et al, 2006a) and TdCRZ1 (Hernández-López et al, 2006b), implicated in salt and osmotic stress in this yeast, have been identified and characterized.…”