Stress responsive proteins of a flor yeast strain during the early stages of biofilm formation

•The flor yeast proteomic stress response is depicted in an early velum forming stage.•More proteins were found to be involved in the ethanol than the acetaldehyde response.•Response to the oxidative stress proteins were the most numerous.•An extracellular glycoprotein, Ygp1p, was highly abundant under the studied condition.•Proteins involved in the response to more than one stress were identified.

Flor yeasts metabolism configures organoleptic properties in Sherry type wines during biological aging. Along this process, yeasts form a biofilm known as flor velum, being the presence of certain stress proteins essential for survival and making them excellent organisms for stress response investigations. In this study, an OFFGEL fractionator coupled to LTQ Orbitrap XL MS equipment was used to identify in a flor yeast strain, the maximum possible number of stress proteins under biofilm formation conditions (BFC) and under non-biofilm formation conditions (NBFC), used as reference. A total of 85 stress response proteins have been detected in a higher content than in the reference condition of which 18 are involved in the response to the lack of fermentable carbon source, 39 in the response to the ethanol stress, 3 in the acetaldehyde resistance and 46 in the oxidative stress response. Three proteins of these 85 were found to respond to three different stresses (Por1p and Tps2p in lack of fermentable carbon source, resistance to ethanol and resistance to oxidative stress; and Tkl1p in the resistance to ethanol, resistance to acetaldehyde and resistance to oxidative stress). Results of this study might lead to the genetic improvement of flor yeast strains.

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