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Pathways for lactose/galactose catabolism by Streptococcus salivarius.
Yi-Ywan M Chen1, Matthew J Betzenhauser, Jennifer A Snyder
1Department of Oral Biology, University of Florida College of Dentistry, 1600 SW Archer Road, P.O. Box 100424, Gainesville 32610, USA.
FEMS Microbiology Letters
|May 15, 2002
Summary
Streptococcus salivarius metabolizes lactose and galactose via the Leloir pathway, lacking a specific lactose phosphotransferase system (PTS). This suggests substrate availability influences sugar metabolism in soft tissue microbes.
Area of Science:
- Microbiology
- Bacterial Metabolism
- Molecular Biology
Background:
- Streptococcus salivarius is a common oral bacterium.
- Understanding carbohydrate metabolism is crucial for microbial physiology.
- Lactose and galactose are important dietary sugars.
Purpose of the Study:
- To elucidate the metabolic pathways for lactose and galactose in Streptococcus salivarius.
- To investigate the role of specific enzymes and transport systems in sugar catabolism.
- To compare substrate utilization strategies with other oral bacteria.
Main Methods:
- Construction of galactokinase and beta-galactosidase deficient mutant strains of S. salivarius.
- Analysis of intracellular lactose hydrolysis and galactose catabolism.
- Comparative analysis of substrate availability and transport systems.
Main Results:
- S. salivarius lacks a lactose-specific phosphoenolpyruvate phosphotransferase system (PTS).
- Intracellular lactose is hydrolyzed by beta-galactosidase.
- Galactose is exclusively catabolized through the Leloir pathway.
- Absence of high-affinity lactose PTS may be linked to higher substrate availability in soft tissues.
Conclusions:
- S. salivarius utilizes the Leloir pathway for galactose metabolism.
- The absence of a lactose-specific PTS in S. salivarius impacts its sugar catabolism strategy.
- Metabolic pathway differences may reflect ecological niches of oral bacteria.