title: β-Galactosidase production by the psychrotolerant yeast Guehomyces pullulans 17-1 isolated from sea sediment in Antarctica and lactose hydrolysis.
abstract: A psychrotolerant yeast Guehomyces pullulans 17-1 was isolated from sea sediment in Antarctica. It was found that it could yield both extracellular and cell-bound β-galactosidase. After optimization of the medium and cultivation conditions, it was found that the yeast strain produced over 17.2 U mL⁻¹ of β-galactosidase activity within 120 h at the flask level while the yeast strain produced over 25.3 U mL⁻¹ of β-galactosidase activity within 144 h during the 2-L fermentation. This is the highest β-galactosidase activity produced by the wild type yeast strains reported so far. However, the optimal pH and temperature for the crude β-galactosidase were 4.0 and 50 °C, respectively. Lactose could be converted into glucose and galactose and a large amount of reducing sugar could be released from milk under catalysis of the yeast culture.
authors.affiliation: Unesco Chinese Center of Marine Biotechnology, Ocean University of China, Yushan Road No. 5, Qingdao, Shandong, China.
authors.forename: Chunli
authors.initials: C
authors.lastname: Song
authors.forename: Zhenming
authors.initials: Z
authors.lastname: Chi
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Xianghong
authors.initials: X
authors.lastname: Wang
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D001487:Basidiomycota / Q000378:metabolism*; D005285:Fermentation; D005516:Food Microbiology; D005690:Galactose / Q000737:chemistry; D019015:Geologic Sediments; D005947:Glucose / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007785:Lactose / Q000737:chemistry / Q000378:metabolism*; D008892:Milk / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013696:Temperature; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D001616:beta-Galactosidase; D005947:Glucose; D007785:Lactose; D005690:Galactose