FERMENTATIVE BEHAVIOUR AND COMPETITION CAPACITY OF CRYOTOLERANT Saccharomyces SPECIES IN LOW NITROGEN WINEMAKING CONDITIONS

SU YING; RODRÍGUEZ MARÍA EUGENIA; ORIGONE ANDREA CECILIA; QUEROL AMPARO; GUILLAMÓN JOSÉ MANUEL; LOPES CHRISTIAN ARIEL

Cork

Simposio; 33rd International Specialised Symposium on Yeasts Exploring and Engineering Yeasts for Industrial Application 26; 2017

University College Cork, Ireland

Nitrogen metabolism of cryotolerant Saccharomyces species during winemaking is little known, although some works have demonstrated that S. uvarum shows lower nitrogen requirements than S. cerevisiae. We evaluated the nitrogen requirements of 32 strains belonging to S. uvarum, S. eubayanus and S. kudriavzevii species. The assays were performed in microplates containing synthetic must with different nitrogen concentrations (0, 40, 60, 80, 100, 120, 140, 160, 180, 200 and 300 mg/L), inoculated with 1 x 106 cells/mL and incubated at 25ºC. Yeast growth was followed by OD measuring and fitted to an exponential model. Kinetic parameters, obtained for all growth curves, evidenced that S. eubayanus strains showed higher μmax than S. uvarum at all nitrogen concentrations, while S. kudriavzevii strains showed the lowest values. One S. eubayanus and one S. uvarum strains, showing low nitrogen requirements, were individually evaluated in competition assays against S. cerevisiae at different fermentation temperatures (12ºC, 20ºC and 28ºC) and nitrogen concentrations (60, 140 and 300 mg/L). Assays were performed in 80 mL synthetic must inoculated with 1 x 106 cells/mL of each species. S. cerevisiae dominated the fermentation at 28ºC while S. uvarum or S. eubayanus dominated at 12ºC, in all three nitrogen concentrations. At 20ºC, S. cerevisiae dominated (more than 90% implantation) the fermentation in musts containing 300 mg/L N while only 40% or 50% implantation was observed at low nitrogen concentrations (60 mg/L). Our results evidence the competition capacity of both S. eubayanus and S. uvarum in low nitrogen must fermented at intermediate temperature.