title: Repeated-batch production of galactooligosaccharides from lactose at high concentration by using alginate-immobilized cells of Sporobolomyces singularis YIT 10047.
abstract: We investigated the production of galactooligosaccharides (GOS) from lactose by alginate-immobilized cells of Sporobolomyces singularis YIT 10047 (IM-SS). beta-Galactosidase activity was stable at 30 to 50 degrees C but decreased dramatically between 50 and 60 degrees C and disappeared at 70 degrees C in acetate buffer. The enzyme activity remaining was no more than 20% of that of unheated samples after incubation in distilled water at 55 degrees C, whereas its value was about 60% at the same temperature under buffered condition. However, activity was maintained more than 80% with 10% to 50% (w/w) lactose after incubation at 55 degrees C without buffer. In a single-batch reaction, GOS yield was 41.0% with free cells and 40.4% with IM-SS. We attempted a repeated-batch reaction using IM-SS with 600 g L(-1)lactose. IM-SS produced GOS stably for 20 batches (22 h/batch, 440 h in total) at 55 degrees C and pH 5.0 or 6.0. IM-SS produced GOS at 242 g L(-1), at a rate of 8.72 g L(-1) h(-1). Both GOS yield and production rate were higher than those in published experiments on GOS production using immobilized biocatalysts. The repeated-batch reaction with IM-SS would be an ideal system for GOS production because of its stability and high productivity.
authors.affiliation: Yakult Central Institute for Microbiological Research, Kunitachi, Tokyo, Japan. takafumi.sakai@yher.be
authors.forename: Takafumi
authors.initials: T
authors.lastname: Sakai
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tsuji
authors.forename: Shinya
authors.initials: S
authors.lastname: Shibata
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Hayakawa
authors.forename: Keisuke
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D000464:Alginates; D001487:Basidiomycota / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D019149:Bioreactors; D001709:Biotechnology / Q000379:methods*; D018914:Cells, Immobilized; D003470:Culture Media; D005690:Galactose / Q000737:chemistry / Q000378:metabolism*; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D007785:Lactose / Q000378:metabolism*; D009844:Oligosaccharides / Q000096:biosynthesis* / Q000737:chemistry; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D000464:Alginates; D003470:Culture Media; D006603:Hexuronic Acids; D009844:Oligosaccharides; D020723:Glucuronic Acid; D001616:beta-Galactosidase; D007785:Lactose; D005690:Galactose