Physiological and genetic characterization of Saccharomyces cerevisiae strains isolated from different sources for production of fermented cereal-beverages

Abstract

Different yeast strains, even belonging to the same species, may have different physiological and genetic characteristics, which make these microorganisms important industrially. The use of yeasts isolated from natural substrates and various fermentation processes can contribute to the development and improvement of fermented foods and beverages, increasing the use and diversification of these microorganisms in several processes. Thus, the objective of the present study was to characterize, physiologically and genetically, different Saccharomyces cerevisiae strains, isolated from different sources, and direct these remarkable strains for their use and improvement in the industrial production of fermented cereal-beverages. Initially, 81 indigenous S. cerevisiae strains isolated from caxiri, kefir, distilleries, cassava, apple fruit, fruit and cocoa fermentation were evaluated. Regarding the enzymatic analyzes, for amylase production, only CCMA 0708, isolated from caxiri, showed low activity for the amylase enzyme. For phytase, the strains analyzed presented significant differences for phytase production, an important characteristic for their application in the cereals beverages production, since phytate (or phytic acid) corresponds to an antinutrient compound. Twenty-eight positive strains selected in the phytase test presented physiological differences when submitted to different stress conditions, such as high temperatures, different pH variations and osmolarities. Regarding genetic tests, evaluated for polymorphisms using Rep-PCR and RAPD-PCR techniques, the strains showed differences in the genetic profile and bands in both tests. In addition, the chromatographic analyzes suggest small differences in the profile of volatile and nonvolatile compounds produced by the strains in a maize-based medium with 24 hours of fermentation. Therefore, the 12 strains selected at the end of this study had potential use in the production of non-alcoholic beverages based on cereals.