Production of killer toxin from Saccharomyces eubayanus using agro-industrial waste and its application against wine spoilage yeasts

SANGORRIN, MARCELA PAULA; MAZZUCCO, MARÍA BELÉN

San Carlos de Bariloche

Simposio; 34th International Specialized Symposium on Yeasts; 2018

IPATEC (UNCo-CONICET)

Juicing industry generates amounts of waste that mostly lack commercial value and produce environmental pollution in the absence of waste treatment policies. On the other hand, microbiological spoilage is a major concern in wine industry, and control tools are limited. Taking these challenges into account, agro-industrial waste coming from ultrafiltrated apple and pear juice (WUJ) were used to grow Saccharomyces eubayanus and to produce its killer toxin (SeKT). A Plackett?Burman screening was performed in order to optimize SeKT production in WUJ. The ?optimized WUJ medium? (16 units of SeKT killer toxin/mL) was characterized: 75% v/v WUJ, 0.5% m/v KH2PO4, 0.5% m/v MgSO4, 0.5% m/v (NH4)SO4, 0.5% g/L urea, 10% v/v glycerol and 0.1 % v/v Triton X-100. SeKT produced in WUJ ?optimized medium? showed antagonistic activity against the beverage spoilage yeasts Brettanomyces bruxellensis, Pichia guilliermondii, Pichia manshurica and Pichia membranifaciens. Inhibition percentage against spoilage species in control medium was 37-57%. Similar inhibition percentages against spoilage species in wine (49-69%) and cider (28-63%) environment was detected and preserved at least for 48 h in both fermented beverages. This work reports for the first time the ability of S. eubayanus to produce a killer toxin with potential use as a biocontrol tool in winemaking. Producing SeKT using agro-industrial wastes as alternative medium to cultivate S. eubayanus would have industrial, economic and ecological benefits.