Genome analysis and engineering of industrial lager brewing yeasts

Doctoral thesis (2019)

Authors

A.R. Gorter de Vries BT/Industriele Microbiologie - AS
Research Group
BT/Industriele Microbiologie (AS) (TU Delft)
Copyright: © 2019 A.R. Gorter de Vries
DOI: https://doi.org/10.4233/uuid:7f6985bb-3383-48f6-bcd3-f2758f35e3c2
CRISPR-Cas Nanopore sequencing Biotechnology Saccharomyces cerevisiae Fermentation Evolution Yeast Brewing Genetics Molecular biology Neofunctionalisation Saccharomyces eubayanus × Saccharomyces cerevisiae hybrids Saccharomyces pastorianus
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Published Date

06-09-2019

Language

English

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Faculty

Applied Sciences

Department

BT/Biotechnologie

Research Group

BT/Industriele Microbiologie

Abstract

Lager beer, also referred
to as Pilsner, is the most popular alcoholic beverage in the world, with an
annual consumption of almost 200 billion litres per year. To make lager beer,
brewer’s wort is fermented with the yeast Saccharomyces
pastorianus. This microorganism converts wort sugars into ethanol and
contributes key flavour compounds to the beer. S.pastorianus is an interspecific hybrid which likely formed about
500 years ago by spontaneous mating between an ale-brewing S. cerevisiae strain and a wild S. eubayanus contaminant.

The genome of lager
brewing yeast is exceptionally complex: not only does it contain chromosomes
from the two parental species, but these have also undergone extensive
recombination and are present in varying copy numbers, a situation referred to
as aneuploidy. The S. eubayanus
ancestor was only discovered in 2011, enabling an improved understanding of the
complex genomeand convoluted evolutionary ancestry of S.pastorianus. Furthermore, recent advances in whole-genome sequencing
technology and in gene editing tools have simplified the genetic accessibility
and amenability of Saccharomycesyeast
genomes. The aim of this thesis was to leverage these advances to investigate
how the genetic complexity of current S.pastorianus
strains emerged and how it contributes to industrial lager brewing performance,
and to develop new methods for strain improvement of brewing yeasts.