Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Oligosaccharide Assembly01:24

Oligosaccharide Assembly

Protein glycosylation starts in the ER lumen and continues in the Golgi apparatus. Glycosyltransferases catalyze the addition of sugar molecules or glycosylation of proteins. Usually, these enzymes add sugars to the hydroxyl groups of selected serine or threonine residues to form O-linked glycans or the amino groups of asparagine residues to form N-linked glycans. Different positions on the same polypeptide chain can contain differently linked glycans.
Multiple sugar molecules that may or may...
Carbohydrate Metabolism01:36

Carbohydrate Metabolism

Carbohydrates are polymers composed of molecules containing atoms of carbon, hydrogen and oxygen. One gram of carbohydrate can provide four kilo-calories of energy, which makes it the most efficient instant energy source.
Starch accounts for approximately 60% of the carbohydrates consumed by humans. Since amylase enzymes cannot function in the stomach's acidic environment, starch can only be digested in the mouth and small intestine. Simple sugars are found naturally in milk and fruits in the...
Glucose Transporters01:27

Glucose Transporters

Glucose transporters facilitate the transport of glucose across the cell membrane. In addition to glucose, some glucose transporters can also aid the movement of other hexoses such as fructose, mannose, and galactose.
Facilitated diffusion-glucose transporters (GLUTs) are encoded by the solute-linked carrier (SLC) family 2, subfamily A gene family, or SLC2A. The 14 GLUT protein members are distributed into three classes:
Overview of Carbohydrate Metabolism01:19

Overview of Carbohydrate Metabolism

Carbohydrate metabolism is a fundamental biochemical process that ensures a constant supply of energy to living cells. The most important carbohydrate is glucose, which can be broken down via glycolysis to enter into the Krebs cycle and eventually lead to the production of ATP through oxidative phosphorylation.
Glucose transport into cells is facilitated by a family of transport proteins called GLUT (Glucose Transporters). GLUT4 is the primary glucose transporter for insulin-stimulated glucose...
Inducible Operons: lac Operon01:25

Inducible Operons: lac Operon

The lac operon in Escherichia coli is a model for understanding inducible gene regulation and metabolic flexibility. It integrates local control by lactose and global regulation through catabolite repression, enabling E. coli to preferentially metabolize glucose when available and switch to lactose utilization when glucose is scarce.Structure and Function of the lac OperonThe lac operon contains three structural genes: lacZ (β-galactosidase), lacY (lactose permease), and lacA (thiogalactoside...
Microbes in Food Production01:29

Microbes in Food Production

Microbial fermentation is central to food biotechnology, enhancing flavor, texture, preservation, and stability. Fermentative microorganisms metabolize carbohydrates into organic acids, alcohols, and other metabolites that inhibit spoilage organisms and improve digestibility while contributing distinctive sensory qualities.In baking, amylases naturally present in flour hydrolyze starch into monosaccharides such as glucose, which Saccharomyces cerevisiae ferments anaerobically. Through...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

The <i>Streptococcus mutans</i> collagen-binding protein Cnm enhances early biofilm formation with <i>Candida albicans</i>.

Applied and environmental microbiology·2026
Same author

Co-infection with Cbp<sup>+</sup> <i>Streptococcus mutans</i> and <i>Candida albicans</i> is associated with root caries in older adults.

Journal of oral microbiology·2026
Same author

Vancomycin-resistant gut commensal Clostridium innocuum emerges as a pathobiont through synergy with toxigenic Clostridioides difficile.

Microbial pathogenesis·2026
Same author

A ComX-based strategy for artificially inducing competence in naturally non-transformable <i>Streptococcus parasanguinis</i>.

Applied and environmental microbiology·2026
Same author

The genomic history of Streptococcus mutans from the Mesolithic until modern times.

Genome biology·2026
Same author

Oral hygiene agents at work: effects on <i>Streptococcus mutans</i> and caries risk.

Frontiers in cellular and infection microbiology·2026

Related Experiment Video

Updated: Jul 12, 2026

Production of Chemicals by Klebsiella pneumoniae Using Bamboo Hydrolysate as Feedstock
07:24

Production of Chemicals by Klebsiella pneumoniae Using Bamboo Hydrolysate as Feedstock

Published on: June 29, 2017

Galactose metabolism by Streptococcus mutans.

Jacqueline Abranches1, Yi-Ywan M Chen, Robert A Burne

  • 1Department of Oral Biology, University of Florida College of Dentistry, P.O. Box 100424, Gainesville, FL 32610, USA.

Applied and Environmental Microbiology
|October 7, 2004
PubMed
Summary

Streptococcus mutans requires both the Leloir and tagatose pathways for efficient galactose utilization. Disrupting the galK gene impairs galactose growth, which cannot be rescued by altering lactose PTS activity.

More Related Videos

Generation of a Gene-disrupted Streptococcus mutans Strain Without Gene Cloning
12:06

Generation of a Gene-disrupted Streptococcus mutans Strain Without Gene Cloning

Published on: October 23, 2017

Purification of a High Molecular Mass Protein in Streptococcus mutans
09:51

Purification of a High Molecular Mass Protein in Streptococcus mutans

Published on: September 14, 2019

Related Experiment Videos

Last Updated: Jul 12, 2026

Production of Chemicals by Klebsiella pneumoniae Using Bamboo Hydrolysate as Feedstock
07:24

Production of Chemicals by Klebsiella pneumoniae Using Bamboo Hydrolysate as Feedstock

Published on: June 29, 2017

Generation of a Gene-disrupted Streptococcus mutans Strain Without Gene Cloning
12:06

Generation of a Gene-disrupted Streptococcus mutans Strain Without Gene Cloning

Published on: October 23, 2017

Purification of a High Molecular Mass Protein in Streptococcus mutans
09:51

Purification of a High Molecular Mass Protein in Streptococcus mutans

Published on: September 14, 2019

Area of Science:

  • Microbiology
  • Bacterial Metabolism
  • Molecular Biology

Background:

  • Streptococcus mutans utilizes various sugars for growth.
  • Galactose metabolism in S. mutans involves the Leloir pathway and potentially the tagatose pathway.
  • The sugar phosphotransferase system (PTS) is crucial for nutrient transport and initial metabolism.

Purpose of the Study:

  • To investigate the role of the galK gene in galactose metabolism in Streptococcus mutans.
  • To determine if the lactose PTS can transport galactose and if enhancing its activity can overcome growth defects.
  • To elucidate the interplay between the Leloir, tagatose, and PTS pathways in galactose utilization.

Main Methods:

  • Insertion inactivation of the galK gene in S. mutans UA159.
  • Construction and analysis of galK and lacR double mutants.
  • Assessing bacterial growth on different carbon sources (galactose, glucose, lactose).
  • Measuring PTS activities and analyzing gene regulation.

Main Results:

  • galK knockout mutants showed significantly impaired growth on galactose, but not glucose or lactose.
  • Elevating lactose PTS activity by mutating lacR did not restore galactose growth.
  • Mutation in the lacA gene of the tagatose pathway impaired growth on both lactose and galactose.
  • Galactose utilization requires functional Leloir and tagatose pathways.

Conclusions:

  • The Leloir pathway, initiated by galactokinase, is essential for efficient galactose growth in S. mutans.
  • The lactose PTS plays a minor role, if any, in galactose transport.
  • The tagatose pathway is also critical for optimal galactose utilization.
  • LacR influences the regulation of the glucose PTS, indicating cross-talk between sugar metabolism pathways.