Comparative study and rapid yeast characterization by molecular analysis for industrial application

Resumo

Yeasts are one of the most important microorganisms currently used in fermentative processes, and well-adapted Saccharomyces cerevisiae strains derived from exhaustive selection are considered an essential, economically viable yeast starters in the industry as bioethanol-producing plants. In order to assure the performance of industrial production, the use of molecular tools is essential for the rapid detection of contamination by wild strains. Morphological identification of yeasts isolated from bioethanol-producing plants was compared with a molecular technique based on restriction fragment length polymorphism of mitochondrial DNA (mtDNA-RFLP). A detailed study of smooth and rough colonies was performed by scanning electron microscopy (SEM). The data showed that the mtDNA-RFLP technique was a highly efficient discriminating tool for yeast strains, allowing correct identification although morphological changes occur in response to stress due to the expression of genes involved in behavior change and/or chromosome rearrangements observed by karyotyping. The majority of the yeasts showed any genetic difference when compared with industrial strains (80-100% confidence). Macroscopically different colonies (smooth or rough) were genetically similar. SEM revealed distinct budding patterns when genotypically similar strains were compared. Therefore the present study suggests that yeasts with similar genotypes can evolve into distinct phenotypes depending on stress conditions.