title: Genome sequence of Saccharomyces carlsbergensis, the world's first pure culture lager yeast.
abstract: Lager yeast beer production was revolutionized by the introduction of pure culture strains. The first established lager yeast strain is known as the bottom fermenting Saccharomyces carlsbergensis, which was originally termed Unterhefe No. 1 by Emil Chr. Hansen and has been used in production in since 1883. S. carlsbergensis belongs to group I/Saaz-type lager yeast strains and is better adapted to cold growth conditions than group II/Frohberg-type lager yeasts, e.g., the Weihenstephan strain WS34/70. Here, we sequenced S. carlsbergensis using next generation sequencing technologies. Lager yeasts are descendants from hybrids formed between a S. cerevisiae parent and a parent similar to S. eubayanus. Accordingly, the S. carlsbergensis 19.5-Mb genome is substantially larger than the 12-Mb S. cerevisiae genome. Based on the sequence scaffolds, synteny to the S. cerevisae genome, and by using directed polymerase chain reaction for gap closure, we generated a chromosomal map of S. carlsbergensis consisting of 29 unique chromosomes. We present evidence for genome and chromosome evolution within S. carlsbergensis via chromosome loss and loss of heterozygosity specifically of parts derived from the S. cerevisiae parent. Based on our sequence data and via fluorescence-activated cell-sorting analysis, we determined the ploidy of S. carlsbergensis. This inferred that this strain is basically triploid with a diploid S. eubayanus and haploid S. cerevisiae genome content. In contrast the Weihenstephan strain, which we resequenced, is essentially tetraploid composed of two diploid S. cerevisiae and S. eubayanus genomes. Based on conserved translocations between the parental genomes in S. carlsbergensis and the Weihenstephan strain we propose a joint evolutionary ancestry for lager yeast strains.
authors.affiliation: Carlsberg Laboratory, Yeast Biology, Gamle Carlsberg Vej 10, Valby, Denmark.
authors.forename: Andrea
authors.initials: A
authors.lastname: Walther
authors.affiliation: Carlsberg Laboratory, Yeast Biology, Gamle Carlsberg Vej 10, Valby, Denmark.
authors.forename: Ana
authors.initials: A
authors.lastname: Hesselbart
authors.affiliation: Carlsberg Laboratory, Yeast Biology, Gamle Carlsberg Vej 10, Valby, Denmark juergen.wendland@carlsberglab.dk.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Wendland
mesh_terms: D002874:Chromosome Mapping; D015825:Chromosomes, Fungal; D019295:Computational Biology; D004271:DNA, Fungal; D005285:Fermentation; D016681:Genome, Fungal; D059014:High-Throughput Nucleotide Sequencing; D008969:Molecular Sequence Data; D011003:Ploidies; D012440:Saccharomyces / Q000235:genetics* / Q000254:growth & development; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development
chemical_list: D004271:DNA, Fungal
keywords: chromosome loss; fermentation; genome evolution; genome sequencing; ploidy