AUTHOR=Martínez Alberto , Zamora Emiliano , Álvarez María L. , Bautista-Gallego Joaquín , Ramírez Manuel 

TITLE=Genetic improvement of non-conventional Torulaspora delbrueckii for traditional sparkling winemaking by mixing for eventual hybridization with Saccharomyces cerevisiae

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1006978

DOI=10.3389/fmicb.2022.1006978

ISSN=1664-302X

ABSTRACT=<p>Non-conventional yeasts such as <italic>Torulaspora delbrueckii</italic> (<italic>Td</italic>) have been proposed for sparkling winemaking. Unfortunately, this yeast has poor efficiency in completing wine fermentation as compared to <italic>Saccharomyces cerevisiae</italic> (<italic>Sc</italic>). New mutants with increased resistance to SO<sub>2</sub>, ethanol, and high CO<sub>2</sub> pressure were previously isolated from spore clones of <italic>Td</italic>. Although these mutants showed improved capability for base wine fermentation, there is still room for genetic improvement of <italic>Td</italic> yeasts until the fermentative capacity of <italic>Sc</italic> is achieved. As an alternative approach, yeast mixture for eventual hybridization of <italic>Td</italic> with <italic>Sc</italic> was assayed in this study. The new yeast mixture clones (<italic>Sc</italic>-mixed <italic>Td</italic>) showed an intermediate phenotype between both parent yeasts for some relevant biotechnological properties, such as resistance to SO<sub>2</sub>, ethanol, copper, high CO<sub>2</sub> pressure, and high temperature, as well as flocculation potential. These properties varied depending on the specific <italic>Sc</italic>-mixed <italic>Td</italic> clone. Several mixture clones showed improved capability for base wine fermentation as compared to the <italic>Td</italic> parent strain, approaching the fermentation capability of the <italic>Sc</italic> parent strain. The organoleptic quality of sparkling wine was also improved by using some mixture clones and this improved quality coincided with an increased amount of acetate and ethyl esters. The genetic stability of some <italic>Sc</italic>-mixed <italic>Td</italic> clones was good enough for commercial yeast production and winery applications.</p>