Growth dynamics and metabolic characteristics of Brettanomyces spp. isolated from wine

Kvasci roda Brettanomyces predstavljaju značajan problem svjetskoj industriji vina, pogotovo vinima sa zaostalim neprevrelim šećerom i vinima nedovoljno zaštićenima sumpornim dioksidom. Proučavan je utjecaj povećane koncentracije glukoze (više od 2 g/L) i povećane koncentracije sumpornog dioksida (60 mg/L slobodnog SO2) s pet različitih izolata Brettanomyces spp. kvasca iz vina, s obzirom na proizvodnju nepoželjnih sekundarnih metabolita. Kao markeri kontaminacije odabrani su 4-etilfenol, 4-etil gvajakol i octena kiselina. Tri mjeseca pratilo se preživljavanje u vinu, a na kraju pokusa je određena koncentracija odabranih markera. Istraživanje je pokazalo da među sojevima postoje određene razlike u preživljavanju i sintezi odabranih sekundarnih metabolita. Glukoza je bila stimulirajući faktor, kako kod rasta, tako i pri sintezi sekundarnih metabolita. Izolati su pokazali određenu osjetljivost na SO2, ali prisutna količina sumpornog dioksida nije uspjela suzbiti proliferaciju Brettanomyces kvasaca, vjerojatno zbog velike početne koncentracije stanica, čime se umanjuje njegovo antimikrobno djelovanje.Yeasts of the genus Brettanomyces represent a significant spoilage issue for the global wine industry, especially for wines with elevated levels of unfermented sugars and wines that are insufficiently protected by sulfur dioxide. The aim of this study was to investigate the influence of unfermented sugars (more than 2 g/L of glucose) and high level of sulfur dioxide (60 mg/L free SO2) on growth and production of undesired metabolites of five different Brettanomyces isolates. 4-ethylphenol, 4-ethyl guaiacol and acetic acid were chosen as contamination markers. The survival of the isolates was followed over the period of three months, and final concentrations of chosen markers were determined at the end of the experiment. The study showed certain differences in survival and metabolite production among the isolates. Glucose was a stimulating factor for growth and metabolite production. The isolates showed certain sensitivity towards sulfur dioxide, but the concentration was not sufficient to prevent microbial proliferation, probably due to large initial concentrations, which decrease it's antimicrobial properties