Saccharomyces kudriavzevii

Etymology

"Saccharomyces" derives from Latinized Greek and means "sugar-mold" or "sugar-fungus", saccharo (σάκχαρις) being the combining form "sugar" and myces (μύκης, genitive μύκητος) being "fungus".

“Kudriavzevii” was named in honor of VI Kudriavzev, a Russian scientist who worked with yeast taxonomy and ecology, and also played a large role in introducing the wild strain of S. paradoxus into science (Naumov et al., 2000).

Other names include:

· S. kudriavzevii is the common scientific name

· Lager yeast

· Pinot Noir yeast

History

Saccharomyces kudriavzevii was initially isolated from decayed leaf (Kaneko & Banno, 1991) but is often isolated from bark of oak trees (Sampaio & Gonçalves, 2008).

Description

This species of yeast is within the Saccharomyces clade and can be isolated from a variety of substrates and is unique in that it cannot live on galactose and is cryotolerant. Shown in Figure 2 is a summary of activity when grown on a variety of substrates. S. kudriavzevii, compared to S. cerevisiae.

Biology

Ecology

Yeast cells can be isolated from a variety of natural substrates – virtually anything that contains sugars – such as decaying fruit, bark, and soil. Optimal growth for many yeasts occurs at 30 – 35 °C, but S. kudriavzevii is adapted to grow at much colder temperatures (Hittinger, 2013).

Life Cycle & Mating

There are two forms at which yeast cells exist in – haploid and diploid – each of which are a part of the reproductive cycle of the organism. These labels have to do with the number of copies of chromosomes the cell hold, diploids having 2n, haploids having 1n. Haploid cells are those that have the ability to mate to haploids of the opposite mating type to form diploids. They have also been found to be hardier when exposed to varying and extreme conditions, so diploid yeast can go through meiosis, a cellular reproduction process, when exposed to these conditions to produce four haploid spores.

Hybridization

Many species within the Saccharomyces sensu stricto clade have been found to hybridize with other species, S. kudriavzevii included. In particular, it hybridizes with S. cerevisiae (Belloch et al., 2009). This hybridization is unique in that it likely resulted from a single hybridization even involving creation of chimeric chromosomes holding some S. kudriavzevii genes and some S. cerevisiae genes (Belloch et al., 2009).

In Biological Research

The hybridization tendencies of S. kudriavzevii have potential for use in investigation regarding yeast evolution, which is commonly used as a model system for evolution in general (Botstein et al.,1997). In particular it may serve as a model for how proteins change through evolution. For example, glycerol, a chemical widely associated with cold-tolerant organisms, is one that is produced only in S. kudriavzevii within the Saccharomyces clade (Belloch et al., 2009). Understanding protein evolution via this model system may help to predict and understand how protein evolution happens under relatively normal circumstances, allowing us to see on a broad scale what happens when cancer and genetic disorders change protein expression within humans.

Genome Sequencing

S. cerevisiae was the first eukaryotic organism to have its genome entirely sequences, another member of the sensu stricto clade (Botstein et al., 1997). Since then, it was discovered that at least 30% of its genes have homologs within the human genome (Botstein et al., 1997). For this reason, yeasts are considered a model organism for a variety of experiments. Incorporation of S. kudriavzevii into this research has offered insights on how yeast evolve to survive in new environments and also how they hybridize to form new species (Belloch et al., 2009).

Other Uses

S. kudriavzevii can be hybridized with S. cerevisiae and is commonly used in production of alcoholic beverages such as lager beer and pinot noir wine (Bing, Han, Liu, Wang, & Bai, 2014).