Properties of a Streptococcus lactis strain that ferments lactose slowly.
Streptococcus lactis 7962, which ferments lactose slowly, has a lactose phosphoenolpyruvate-dependent phosphotransferase system and low phospho-beta-galactosidase activity, in addition to high beta-galactosidase activity. Lactose 6'-phosphate accumulated to a high concentration (greater than 100 mM) in cells growing on lactose. In contrast, lactic streptococci, which ferment lactose rapidly and use only the lactose-phosphotransferase system for uptake, contained high phospho-beta-galactosidase activity and low concentrations (0.9 to 1.6 mM) of lactose 6'-phosphate. It is concluded that rate-limiting phospho-beta-galactosidase activity is primarily responsible for defective lactose metabolism in S. lactis 7962.
D005285:Fermentation; D006026:Glycoside Hydrolases; D013294:Lactococcus lactis / Q000201:enzymology*; D007785:Lactose / Q000378:metabolism*; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism; D013403:Sugar Phosphates / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
D013403:Sugar Phosphates; C040076:lactose 6'-phosphate; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D006026:Glycoside Hydrolases; D001616:beta-Galactosidase; C022361:6-phospho-beta-galactosidase; D007785:Lactose