Polysaccharase activity in Streptococcus agalactiae (group B streptococci)

Area of Science:

• Microbiology
• Biochemistry

Background:

• Streptococcus agalactiae is a significant human pathogen.
• Polysaccharide degradation capabilities are important virulence factors for bacteria.

Purpose of the Study:

• To investigate the polysaccharase activity of Streptococcus agalactiae.
• To characterize the starch-degrading enzymes produced by S. agalactiae.

Main Methods:

• Isolation and characterization of 300 Streptococcus agalactiae strains from human sources.
• Assay of polysaccharase activity using Columbia agar base medium.
• Testing degradation of various polysaccharides including starch, glycogen, pullulan, amylopectin, and amylose.

Main Results:

• 97% of isolated Streptococcus agalactiae strains degraded starch.
• Representative strains also degraded glycogen, pullulan, amylopectin, and amylose.
• Polysaccharase activity was visualized as clearing zones on agar, though weaker than in some Streptococcus pyogenes strains.
• Enzyme activity was inhibited by the presence of easily metabolized sugars and did not produce fermentable products.

Conclusions:

• Streptococcus agalactiae possesses significant starch and related polysaccharide degrading capabilities.
• This polysaccharase activity can be readily detected in vitro.
• The enzyme activity is sensitive to nutrient availability and sugar metabolism.