title: Cold-active acid beta-galactosidase activity of isolated psychrophilic-basidiomycetous yeast Guehomyces pullulans.
abstract: In the present study, psychrophilic yeasts, which grow on lactose as a sole carbon source at low temperature and under acidic conditions, were isolated from soil from Hokkaido, Japan. The phenotypes and sequences of 28S rDNA of the isolated strains indicated a taxonomic affiliation to Guehomyces pullulans. The isolated strains were able to grow on lactose at below 5 degrees C, and showed cold-active acid beta-galactosidase activity even at 0 degrees C and pH 4.0 in the extracellular fractions. Moreover, K(m) of beta-galactosidase activity for lactose in the extracellular fraction from strain R1 was found to be 50.5 mM at 10 degrees C, and the activity could hydrolyze lactose in milk at 10 degrees C. The findings in this study indicate the possibility that the isolated strains produce novel acid beta-galactosidases that are able to hydrolyze lactose at low temperature.
authors.affiliation: Department of Food Science and Technology, Faculty of Bioindustry, Tokyo University of Agriculture, Yasaka 196, Abashiri, Hokkaido 099-2493, Japan. t-nakaga@bioindustry.nodai.ac.jp
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Ryoko
authors.initials: R
authors.lastname: Ikehata
authors.forename: Masataka
authors.initials: M
authors.lastname: Uchino
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Miyaji
authors.forename: Katsumi
authors.initials: K
authors.lastname: Takano
authors.forename: Noboru
authors.initials: N
authors.lastname: Tomizuka
mesh_terms: D001483:Base Sequence; D001487:Basidiomycota / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D003080:Cold Temperature; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007785:Lactose / Q000378:metabolism; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012339:RNA, Ribosomal, 28S / Q000737:chemistry / Q000235:genetics; D017422:Sequence Analysis, DNA; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D004271:DNA, Fungal; D012339:RNA, Ribosomal, 28S; D001616:beta-Galactosidase; D007785:Lactose