Summary auto-generated
This study evaluated genetic variation among 35 yeast strains representing four recognized Saccharomyces sensu stricto species using electrophoretic analysis of four enzymes: nonspecific esterases, acid phosphatase, lactate dehydrogenase, and glucose-6-phosphate dehydrogenase. The researchers identified 22 distinct electrophoretic types and demonstrated that three enzymes (esterases, acid phosphatase, and glucose-6-phosphate dehydrogenase) could clearly distinguish all four species: S. cerevisiae, S. bayanus, S. pastorianus, and S. paradoxus. S. cerevisiae showed the highest polymorphism, particularly in lactate dehydrogenase patterns, while S. paradoxus was the most homogeneous species. When lactate dehydrogenase data were excluded from numerical analysis, cluster analysis achieved excellent separation of all four species with a high co-phenetic correlation coefficient of 0.986. Results correlated well with DNA hybridization studies, confirming the method's utility for rapid identification of these industrially important yeasts used in brewing, wine-making, and baking without requiring sophisticated equipment or laborious procedures.
Key findings
- Electrophoretic analysis of three enzymes (EST, ACP, and G6PD) successfully distinguished all four Saccharomyces sensu stricto species, with 22 distinct electrophoretic types identified among 35 strains.
- S. cerevisiae exhibited the highest intraspecific polymorphism while S. paradoxus was the most homogeneous species, likely due to its restriction to natural habitats.
- Lactate dehydrogenase contributed excessive intraspecific variation that obscured interspecific differentiation; excluding this enzyme improved cluster consistency and species separation.
- Numerical cluster analysis without LDH data achieved excellent species discrimination with within-cluster similarity greater than 0.50 and co-phenetic correlation coefficient of 0.986.
- The isoenzyme method provides a rapid, user-friendly, and reliable tool for identifying Saccharomyces sensu stricto isolates without sophisticated equipment, with results concordant with DNA-based identification methods.
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Abstract
Genetic variation among 35 strains representing the four currently recognized species of Saccharomyces sensu stricto (Saccharomyces cerevisiae, Saccharomyces bayanus, Saccharomyces pastorianus/carlsbergensis and Saccharomyces paradoxus) was estimated by analysing the electrophoretic mobilities of nonspecific esterases, acid phosphatase, lactate dehydrogenase and glucose-6-phosphate dehydrogenase isoenzymes. Twenty-two electrophoretic types were identified, a result in agreement with the phenotypic and genetic polymorphisms reported for this group of yeasts. However, the four species were clearly distinguishable based on the patterns obtained using three of the enzymes assayed, the resolving power not being improved by the introduction of data correspondent to lactate dehydrogenase. The overall diversity was higher among S. cerevisiae isolates, in contrast with S. paradoxus which showed only two patterns, one of which was common to four of the five strains studied. Concordant results from the application of the method and DNA hybridization experiments demonstrate its value for identification purposes.