Production of Galacto-Oligosaccharides Using Kluyveromyces Yeast

Galacto-oligosaccharides are known for their prebiotic activity. They are obtained from lactose using bacterial or fungal betagalactosidases. This article describes the factors that affect the biosynthesis and purification of galacto-oligosaccharides using Kluyveromyces yeasts, as well as summarizes some prospective research areas in this sphere. The research covered ten years of scientific publications on the production of galacto-oligosaccharides with yeast beta-galactosidases. The review pool included 87 articles published in peer-reviewed journals and registered in Scopus, Web of Science, PubMed, and eLIBRARY.RU. The yield, composition, and properties of galacto-oligosaccharides depend on the enzyme, its application, biosynthesis optimization, and purification conditions. Beta-galactosidases from Kluyveromyces can simultaneously catalyze hydrolysis and transgalactosylation reactions. The biosynthesis conditions vary a lot across the review pool, as does the yield of galacto-oligosaccharides, which usually remains below 30–40% while the total lactose conversion reaches 80–90%. Kluyveromyces beta-galactosidases can be used as whole-cell enzymes in immobilized form or together with other enzymes. They improve the economic indicators of biosynthesis, and / or the yield and / or the structure of galacto-oligosaccharides. If synthesized directly in milk or whey, galacto-oligosaccharides may yield new functional dairy products and additives. The method of selective bioconversion with Kluyveromyces yeast brings the purity of galacto-oligosaccharides up to 90% in an economical and sustainable way. Eventually, galacto-oligosaccharides can be obtained from dairy by-products. Other promising areas include the enzymic mixes of different producers, as well as a comprehensive use of Kluyveromyces beta-galactosidases for galacto-oligosaccharide biosynthesis and purification.