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Chromosomal structures of bottom fermenting yeasts
1Brewing Research & Development Laboratory, Asahi Breweris, LTD, Ibaraki, Japan.
Systematic and Applied Microbiology
|December 20, 1999
Summary
Genomic analysis reveals bottom fermenting yeasts possess chromosomes from both Saccharomyces cerevisiae and Saccharomyces bayanus. This suggests bottom fermenting yeasts should be classified as Saccharomyces carlsbergensis.
Area of Science:
- Yeast genomics
- Brewing microbiology
- Molecular systematics
Background:
- Bottom fermenting yeasts are crucial in brewing.
- Their precise taxonomic classification remains debated.
- Understanding their genomic origins is key to their identity.
Purpose of the Study:
- To genomically compare bottom fermenting yeasts.
- To clarify the taxonomic status of bottom fermenting yeasts.
- To investigate the chromosomal composition of key yeast strains.
Main Methods:
- Pulsed-field gel electrophoresis (PFGE) for chromosome separation.
- Southern blot analysis using Saccharomyces cerevisiae gene probes.
- Hybridization techniques to differentiate yeast chromosomes.
Main Results:
- Bottom fermenting yeasts contain chromosomes from both S. cerevisiae and S. bayanus.
- S. pastorianus (type strain CBS1538) exclusively shows S. bayanus chromosomes.
- S. carlsbergensis (CBS1513) exhibits chromosomes from both S. cerevisiae and S. bayanus.
- Top fermenting yeasts are confirmed as S. cerevisiae based on chromosomal structure.
Conclusions:
- Bottom fermenting yeasts exhibit a hybrid genomic profile.
- The genomic evidence supports classifying bottom fermenting yeasts as S. carlsbergensis.
- This classification clarifies the distinct origins of top and bottom fermenting yeasts.