Yeasts from indigenous culture for cachaça production and brewer's spent grain: Biodiversity and phenotypic characterization for biotechnological purposes

Abstract

In this study, yeasts were isolated from an indigenous starter culture for cachaça production (Brazilian spirit) and brewer’s spent grain and characterized through a series of phenotypic assays: the killer profile, ascospore formation capacity, growth at high temperatures, resistance to natamycin and actidione, and exoenzyme production. One hundred thirty-four (n = 134) yeasts were isolated and identified as belonging to 6 genera and 10 different species. The ascospore formation in potassium acetate agar was observed in 86% of the isolates (73 Saccharomyces cerevisiae, 3 Torulaspora delbrueckii, and 1 Wickerhamomyces anomalus) highlighting their potential for microencapsulation. Only S. cerevisiae LMQA SNR 70 expressed an effective killer factor (ability to destroy sensitive strains), while only 3 S. cerevisiae, 1 Clavispora lusitaniae, and 1 Pichia kudriavzevii isolates were able to grow up at 45 °C. At 50 and 100 mg/L, actidione showed selectivity action for Candida parapsilosis, while natamycin inhibited the growth of all isolates. The non-Saccharomyces isolates stood out in the qualitative and quantitative tests for amylolytic, pectinolytic, cellulolytic, and xylanolytic activities. A predominance of the species W. anomalus and T. delbrueckii was observed. Besides, quantitative tests revealed that 23% of the isolates exhibited exoenzymatic activity in a nutrient-poor environment, and W. anomalus LMQA CSC 5 e LMQA CSC 43 stood out for the multi-enzymatic in agar and liquid medium response. The phenotypic profile showed that 16% of the isolates expressed two or more characteristics studied, with 2/3 represented by the non-Saccharomyces species. These results highlight the importance of studying yeast species for new biotechnological purposes.