Bacteriocin of a group B streptococcus: partial purification and characterization

Area of Science:

• Microbiology
• Bacteriology
• Biochemistry

Background:

• Group B Streptococcus (GBS) is a significant human pathogen.
• Bacteriocins are ribosomally synthesized antimicrobial peptides with narrow-spectrum activity.
• Understanding GBS bacteriocin production may offer novel therapeutic strategies.

Purpose of the Study:

• To investigate the production and characteristics of bacteriocin-like substances from Group B Streptococcus.
• To identify and partially purify a novel bacteriocin from GBS.

Main Methods:

• Screening of 135 GBS strains for antimicrobial activity against various bacteria.
• Extraction and partial purification of the active substance using ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography.
• Characterization of the bacteriocin's physical properties, stability, and activity spectrum.

Main Results:

• Two of 135 GBS strains produced bacteriocin-like inhibition, active against gram-positive but not gram-negative bacteria.
• The purified bacteriocin, termed streptocin B(1), exhibited bactericidal activity.
• Streptocin B(1) production was repressed by fermentable carbohydrates and enhanced by yeast extract.
• The bacteriocin exists in two interconvertible forms (MW 10,000 and >200,000), is inactivated by proteases, and is stable in mild acid but labile in alkali.

Conclusions:

• Group B Streptococcus can produce bacteriocins, such as streptocin B(1), with specific antimicrobial activity.
• Nutrient availability significantly influences streptocin B(1) production.
• Streptocin B(1) possesses distinct physical properties and stability characteristics, suggesting potential for further investigation and application.