Galactokinase activity in Streptococcus thermophilus

Journal Article · Tue Oct 01 00:00:00 EDT 1985 · Appl. Environ. Microbiol.; (United States)

OSTI ID:5687489

Hutkins, R; Morris, H A; McKay, L L

ATP-dependent phosphorylation of (/sup 14/C)galactose by 11 strains of streptococcus thermophilus indicated that these organisms possessed the Leloir enzyme, galactokinase (galK). Activities were 10 times higher in fully induced, galactose-fermenting (Gal/sup +/) strains than in galactose-nonfermenting (Gal/sup -/) strains. Lactose-grown, Gal/sup -/ cells released free galactose into the medium and were unable to utilize residual galactose or to induce galK above basal levels. Gal/sup +/ S. thermophilus 19258 also released galactose into the medium, but when lactose was depleted, growth on galactose commenced, and galK increased from 0.025 to 0.22 ..mu..mol of galactose phosphorylated per min per mg of protein. When lactose was added to galactose-grown cells of S. thermophilus 19258, galK activity rapidly decreased. These results suggest that galK in Gal/sup +/ S. thermophilus is subject to an induction-repression mechanism, but that galK cannot be induced in Gal/sup -/ strains.

• Research Organization: Univ. of Minnesota, St. Paul
• OSTI ID: 5687489
• Journal Information: Appl. Environ. Microbiol.; (United States), Vol. 50:4
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
GALACTOSE
PHOSPHORYLATION
PHOSPHOTRANSFERASES
ENZYME ACTIVITY
STREPTOCOCCUS
FERMENTATION
LACTOSE
ALDEHYDES
BACTERIA
BIOCONVERSION
CARBOHYDRATES
CHEMICAL REACTIONS
DISACCHARIDES
ENZYMES
HEXOSES
MICROORGANISMS
MONOSACCHARIDES
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
PHOSPHORUS-GROUP TRANSFERASES
SACCHARIDES
TRANSFERASES
550700* - Microbiology