Differential sulfite resistance as a domestication signature in Saccharomyces uvarum

RODRIGUEZ MARIA EUGENIA; BARRIO ELADIO; LOPES CHRISTIAN ARIEL; GUTIERREZ MACIAS LAURA; PEREZ TORRADO ROBERTO; GONZALEZ FLORES MELISA; QUEROL AMPARO

Cork

Simposio; 33th International Specialised Symposium on Yeast; 2017

Microbiology Society

A number of S. uvarum strains has been isolated from natural and anthropic habitats during the last years, but little information is still available on the distribution and possible domestication events in its cryotolerant species. Sulphite tolerance has been described as a domestication signature in S. cerevisiae; for that reason, we proposed the evaluation of the effect of this preservative in 61 S. uvarum strains obtained from diverse natural and anthropic habitats. The assays were performed in YPD-TA agar plates (pH 3.5 by tartaric acid addition). The plates contained 0, 1, 2, 3, 4, 5, 6, 7 and 8 mM sulphite and the inoculation was carried out by means of serial dilutions and dropping onto the agar plates. Strains isolated from natural habitats and apple chichas were only able to grow until 2mM sulphite concentrations. Contrarily, strains from cider or wine exhibited resistance to 4 or 5 mM sulphite. In particular, strains CECT12600 and BMV58 isolated from wine environments grew even at sulphite concentrations of 8 mM. These two resistant strains as well as two sensitive strains (NPCC 1314 from apple chicha and NPCC 1290 from natural habitat) were selected to perform microfermentations (100 mL) in synthetic must at 25ºC. At different fermentation times, samples were collected and the expression of SSU1 gene quantified by quantitative RT-PCR. During the whole fermentation, wine strains overexpressed of SSU1 significantly (10-25 fold higher expression than sensitive strains). Our results suggest that expression of SSU1 gene is a domestication signature in S. uvarum evolution.