title: Analysis of aging in lager brewing yeast during serial repitching.
abstract: Serial repitching of brewing yeast inoculates is an important economic factor in the brewing industry, as their propagation is time and resource intensive. Here, we investigated whether replicative aging and/or the population distribution status changed during serial repitching in three different breweries with the same brewing yeast strain but different abiotic backgrounds and repitching regimes with varying numbers of reuses. Next to bud scar numbers the DNA content of the Saccharomyces pastorianus HEBRU cells was analyzed. Gene expression patterns were investigated using low-density microarrays with genes for aging, stress, storage compound metabolism and cell cycle. Two breweries showed a stable rejuvenation rate during serial repitching. In a third brewery the fraction of virgin cells varied, which could be explained with differing wort aeration rates. Furthermore, the number of bud scars per cell and cell size correlated in all 3 breweries throughout all runs. Transcriptome analyses revealed that from the 6th run on, mainly for the cells positive gene expression could be seen, for example up-regulation of trehalose and glycogen metabolism genes. Additionally, the cells' settling in the cone was dependent on cell size, with the lowest and the uppermost cone layers showing the highest amount of dead cells. In general, cells do not progressively age during extended serial repitching.
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Microbiology, Permoserstraße 15, 04318 Leipzig, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Bühligen
authors.affiliation: Leibniz University Hannover, Institute of Technical Chemistry, Callinstraße 5, 30167 Hannover, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Lindner
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Microbiology, Permoserstraße 15, 04318 Leipzig, Germany; Stockholm University, Stockholm Resilience Center, Kräftriket 2B, 11419 Stockholm, Sweden.
authors.forename: Ingo
authors.initials: I
authors.lastname: Fetzer
authors.affiliation: Leibniz University Hannover, Institute of Technical Chemistry, Callinstraße 5, 30167 Hannover, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Stahl
authors.affiliation: Leibniz University Hannover, Institute of Technical Chemistry, Callinstraße 5, 30167 Hannover, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Scheper
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Microbiology, Permoserstraße 15, 04318 Leipzig, Germany.
authors.forename: Hauke
authors.initials: H
authors.lastname: Harms
authors.affiliation: Helmholtz Centre for Environmental Research - UFZ, Department of Environmental Microbiology, Permoserstraße 15, 04318 Leipzig, Germany. Electronic address: susann.mueller@ufz.de.
authors.forename: Susann
authors.initials: S
authors.lastname: Müller
mesh_terms: D001515:Beer; D002453:Cell Cycle / Q000502:physiology; D048429:Cell Size; D016922:Cellular Senescence / Q000502:physiology*; D016000:Cluster Analysis; D004271:DNA, Fungal / Q000032:analysis; D005285:Fermentation; D019649:Food Industry; D015870:Gene Expression; D020869:Gene Expression Profiling; D012440:Saccharomyces / Q000166:cytology / Q000235:genetics / Q000378:metabolism
chemical_list: D004271:DNA, Fungal
keywords: Bud scar counting; DNA content; Replicative aging; Saccharomyces pastorianus HEBRU; Serial repitching