Isolation and preliminary characterization of Streptococcus cremoris (strain 202) bacteriocin

Area of Science:

• Microbiology
• Bacteriocins
• Streptococcus cremoris

Background:

• Bacteriocins are antimicrobial peptides with significant biotechnological potential.
• Streptococcus cremoris is a key species in dairy fermentations.
• Limited information exists on bacteriocin production within S. cremoris strains.

Purpose of the Study:

• To investigate the bacteriocin-producing capabilities of Streptococcus cremoris strains.
• To characterize a novel bacteriocin, lactostrepcin, produced by S. cremoris strain 202.
• To explore the genetic basis of lactostrepcin production.

Main Methods:

• Screening of 17 S. cremoris strains for bacteriocin production.
• Preliminary characterization of the bacteriocin's activity spectrum.
• Plasmid profiling of the producing strain and its variants.

Main Results:

• Only one of 17 S. cremoris strains (strain 202) produced bacteriocin (lactostrepcin).
• Lactostrepcin exhibited activity against lactic streptococci, Bacillus cereus, Leuconostoc, and Lactobacillus species.
• Strain 202 harbored plasmids, but their direct role in lactostrepcin production was not confirmed.
• Plasmid patterns of lactostrepcin-negative variants could be altered or unchanged compared to the parent strain.

Conclusions:

• Streptococcus cremoris strain 202 produces a distinct bacteriocin, lactostrepcin.
• Lactostrepcin possesses a broad antimicrobial spectrum, suggesting potential applications.
• The genetic determinants for lactostrepcin production may be plasmid-located, but this requires further validation.