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Comparison of molecular and enological features of Saccharomyces uvarum from natural habitats and fermented beverages in Patagonia
RODRÍGUEZ M.E; REBOZZIO R.; LOPES C.A.
Mar del Plata
Congreso; VIII Congreso Argentino de Microbiología General (SAMIGE); 2012
Saccharomyces uvarum is a genetically and physiologically homogeneous group of yeasts frequently found in cider and wine fermentations carried out at low temperature. This species has a great interest in winemaking due to its cryotolerance and its capacity to produce beverages with high levels of aromatic compounds. In this work we made a molecular and physiological comparison of two sets of S. uvarum strains showing different mtDNA-RFLP patterns: 14 strains from traditionally fermented apple juice and 5 strains from natural habitats (Araucaria araucana trees) from Patagonia. In order to detect some genetic differences among natural and fermentative isolates, we evaluated the PCR-RFLP patterns of 33 different genes distributed along the 16 chromosomes of S. uvarum. PCR-RFLP patterns from S. uvarum collection strains were used for comparison. One new allele was detected among strains from natural habitats and one new allele among strains from traditional fermentations. Phylogenetic relationships between representative strains were then evaluated by sequencing of eight nuclear and one mitochondrial genes. Strains from traditional fermentations exhibited a closer relationship with European fermentative strains than with natural Patagonian strains. Natural strains seem to be an isolated group of S. uvarum strains. Only for some genes (MET6 and BRE5) the same allele was found in strains from Araucaria and strain from traditional fermentations. The subtelomeric gene MNL1 in the S. uvarum strain NPCC 1309 from a traditional fermentation corresponded to a Saccharomyces cerevisiae allele, indicating a possible introgression event between both fermentative species. Monosporic cultures derived from each S. uvarum strain were used to perform microfermentations on synthetic must at 13°C. At the end of fermentations, ethanol, glucose, fructose and glycerol contents were measured with enzymatic kits. Volatile acidity was also evaluated by distillation and titratation. No differences were detected among natural strains and strains from fermentations with regard to volatile acidity, glucose and fructose contents at the end of fermentations. However, strains from natural habitats produced a higher glycerol and a lower ethanol concentration (means 9,32 g/L and 10,8 % v/v respectively) than strains from fermentations (means 7,81 g/L and 11,0 % v/v respectively). Enzimatic activities including β-glucosidase and protease, as well as killer behaviour were evaluated among S. uvarum strains in solid media. All isolates showed protease activity independently of the origin. Killer activity was more frequent in strains from natural habitats (100% vs 36%) and β-glucosidase more frequent among strains from fermentations (86% vs 33%). In this work two genetically and physiologically different sets of S. uvarum strains were described; these strains have a great potential in wine industry.