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Lachancea (kluyveromyces) thermotolerans is a ubiquitous yeast that can be naturally found in grapes but also in other habitats as soil, insects and plants, extensively distributed around the world. In a 3-day culture, it shows spherical to ellipsoidal morphology appearing in single, paired cells or short clusters. It is a teleomorph yeast with 1'4 spherical ascospores and it is characterized by a low production of volatile acidity that helps to control global acetic acid levels in mixed or sequential inoculations with either S. cerevisiae or other non-Saccharomyces species. It has a medium fermentative power, so it must be used in sequential or mixed inoculations with S. cerevisiae to get dry wines. It shows a high production of lactic acid able to affect strongly wine pH, sometimes decreasing wine pH by 0.5 units or more during fermentation. Most of the acidification is produced at the beginning of fermentation facilitating the effect in sequential fermentations because it is more competitive at low alcoholic degree. This application is especially useful in warm areas affected by climatic change. pH reduction is produced in a natural way during fermentation and prevents the addition of tartaric acid, that produces tartrate precipitations, or the use of cation exchangers resins highly efficient reducing pH but with undesirable effects on wine quality. Production of lactic acid is done from sugars thus reducing slightly the alcoholic degree, especially in strains with high production of lactic acid. Also, an improvement in the production of 2-phenylethanol and glycerol has been described. [ABSTRACT FROM AUTHOR]

Glycerophospholipids (GP) are the building blocks of cellular membranes and play essential roles in cell compartmentation, membrane fluidity or apoptosis. In addition, GPs are sources for multifunctional second messengers. Whereas the genome and proteome of the most intensively studied eukaryotic model organism, the baker’s yeast (Saccharomyces cerevisiae), are well characterized, the analysis of its lipid composition is still at the beginning. Moreover, different yeast species can be distinguished on the DNA, RNA and protein level, but it is currently unknown if they can also be differentiated by determination of their GP pattern. Therefore, the GP compositions of five different yeast strains, grown under identical environmental conditions, were elucidated using high performance liquid chromatography coupled to negative electrospray ionization-hybrid linear ion trap-Fourier transform ion cyclotron resonance mass spectrometry in single and multistage mode. Using this approach, relative quantification of more than 100 molecular species belonging to nine GP classes was achieved. The comparative lipidomic profiling of Saccharomyces cerevisiae, Saccharomyces bayanus, Kluyveromyces thermotolerans, Pichia angusta, and Yarrowia lipolytica revealed characteristic GP profiles for each strain. However, genetically related yeast strains show similarities in their GP compositions, e.g., Saccharomyces cerevisiae and Saccharomyces bayanus.

Lachancea (kluyveromyces) thermotolerans is a ubiquitous yeast that can be naturally found in grapes but also in other habitats as soil, insects and plants, extensively distributed around the world. In a 3-day culture, it shows spherical to ellipsoidal morphology appearing in single, paired cells or short clusters. It is a teleomorph yeast with 1–4 spherical ascospores and it is characterized by a low production of volatile acidity that helps to control global acetic acid levels in mixed or sequential inoculations with either S. cerevisiae or other non-Saccharomyces species. It has a medium fermentative power, so it must be used in sequential or mixed inoculations with S. cerevisiae to get dry wines. It shows a high production of lactic acid able to affect strongly wine pH, sometimes decreasing wine pH by 0.5 units or more during fermentation. Most of the acidification is produced at the beginning of fermentation facilitating the effect in sequential fermentations because it is more competitive at low alcoholic degree. This application is especially useful in warm areas affected by climatic change. pH reduction is produced in a natural way during fermentation and prevents the addition of tartaric acid, that produces tartrate precipitations, or the use of cation exchangers resins highly efficient reducing pH but with undesirable effects on wine quality. Production of lactic acid is done from sugars thus reducing slightly the alcoholic degree, especially in strains with high production of lactic acid. Also, an improvement in the production of 2-phenylethanol and glycerol has been described.

Background and Aims: The impact of yeast strain and species on the aroma and flavour of Pinot Noir wine was investigated using grapes treated with high hydrostatic pressure (HHP) to inactivate naturally occurring yeast and bacteria. Methods and Results: Pinot Noir grapes were treated by HHP resulting in inactivation of all viable yeast and bacterial cells. Grapes were then inoculated with either Saccharomyces cerevisiae RC212, Assmanshausen (AMH), MERIT.ferm, S. cerevisiae bayanus EC1118, or a blend of MERIT.ferm and Kluyveromyces thermotolerans (SYMPHONY). Descriptive analysis of wines revealed significant differences in overall fruity, red fruit, dark fruit, and jammy/cooked aromas. Principle component analysis showed wines produced by EC1118 and RC212 were characterized by higher dark fruit and jammy aromas while MERIT.ferm produced wine characterized by red fruit and floral aromas. Wines produced from AMH and SYMPHONY trended towards higher overall aged aromas and lower fruity and floral aromas. Conclusions: Yeast strain significantly impacted Oregon Pinot Noir wine aroma with some yeast strains producing wines with increased red and dark fruit aromas while others had reduced fruity aromas and higher aged aromas. Growth of Kluyveromyces thermotolerans during the early stages of fermentation resulted in a decrease in red fruity aromas. Significance of Study: Use of HHP in combination with sterile micro-fermentors allowed the impact of specific yeast on Pinot Noir aroma and flavor to be investigated. Differences in fruity aromas between Pinot Noir wines fermented by different yeast, including a non- Saccharomyces yeast, suggest that yeast strain and species can have a significant impact on Pinot Noir aroma. [ABSTRACT FROM AUTHOR]

Abstract: The efficacy of two strains of Kluyveromyces thermotolerans in preventing the growth and ochratoxin A (OTA) accumulation of ochratoxigenic fungi both “in vitro” and “in situ” was evaluated. The data from this study showed that both yeast strains were able to control Aspergillus carbonarius and A. niger aggregate species growth and ochratoxin A accumulation. The inhibitory effects were dependent on the ochratoxigenic species, yeast strains, aw and temperature evaluated and their interactions. Over all conditions assayed, ochratoxin A accumulation was reduced from 3% to 100% and the growth rate from 11% to 82.5%, depending on conditions. These results are promising for future development of a bio-pesticide. [Copyright &y& Elsevier]

Abstract: Multistarter fermentations of Hanseniaspora uvarum, Torulaspora delbrueckii and Kluyveromyces thermotolerans together with Saccharomyces cerevisiae were studied. In grape musts with a high sugar content, mixed trials showed a fermentation behaviour and analytical profiles of wines comparable to or better than those exhibited by a pure culture of S. cerevisiae. Sequential trials of T. delbrueckii and K. thermotolerans revealed a sluggish fermentation, while those of H. uvarum exhibited an unacceptable increase in ethyl acetate content (175 ml l−1). A low fermentation temperature (15 °C) of multistarter trials of H. uvarum resulted in a stuck fermentation that was not due to a deficiency of assimilable nitrogenous compounds since lower amounts of these compounds were used. Sequential fermentation carried out by H. uvarum at 15 °C confirmed the high production of ethyl acetate. The persistence and level of non-Saccharomyces yeasts during multistarter fermentations under stress conditions (high ethanol content and/or low temperature) can cause stuck fermentations. [Copyright &y& Elsevier]