Yeast as a Source of β-Glucans

Yeasts are unicellular fungi that reproduce asexually through budding or fission and sexually through spore formation. Currently, 500 yeast species are recognised. The most often used yeasts are S. cerevisiae, which are used in winemaking and brewing and the creation of a variety of nutraceutical goods . Most commercially available hormones are produced using recombinant S. cerevisiae. Insulin and glucagon are two of these hormones .

S. cerevisiae has a thick cell wall made up of polysaccharides and proteins which protects the inner compartments of the cell . Up to 55% of the cell wall is composed of β-glucans of 1,3 linkage and 12% of 1,6 β-glucans. Yeast-derived β-glucans contain a linear backbone of (1,3)-linked D-glucose molecules with (1–6) side chains of various lengths. In yeast β-glucans, synthesis can occur in various cell regions. The formation initially occurs in the plasma membrane and is then catalysed enzymatically. The enzyme involved in β-glucan synthesis is β-glucan synthase, encoded by the FKS1 and FKS2 genes. The synthase linked to the cell membrane of S. cerevisiae employs UDP-glucose as a substrate.

S. cerevisiae is an industrial microorganism used for protein, chemical, and metabolite synthesis. The unicellular eukaryote is one of the most researched and utilised industrial microorganisms. It is used to make numerous industrial compounds and heterologous proteins in addition to alcohol fermentation, baking, and bio-ethanol processes. Beer production can generate important byproducts in the form of spent brewer’s yeasts which contains β-glucans.