A bacteriocin produced by certain M-type 49 Streptococcus pyogenes strains when incubated anaerobically

Area of Science:

• Microbiology
• Bacteriology
• Molecular Biology

Background:

• Group A Streptococcus (GAS) M-type 49 strains are significant human pathogens.
• Bacteriocin production is a key characteristic used for typing and epidemiological studies of bacteria.
• Previous studies focused on aerobic conditions for bacteriocin detection, potentially missing anaerobic production.

Purpose of the Study:

• To investigate bacteriocin production in M-type 49 group A streptococci under anaerobic conditions.
• To characterize the novel bacteriocin produced by these strains.
• To evaluate the utility of bacteriocin production for differentiating M-type 49 GAS strains.

Main Methods:

• P-typing of 75 M-type 49 group A streptococci strains under aerobic and anaerobic conditions.
• Isolation and partial purification of the bacteriocin using freeze-thaw elution, ammonium sulfate precipitation, and Sephadex chromatography.
• Analysis of molecular weight, heat stability, and inhibitory spectra of the purified bacteriocin.
• Comparison of the novel bacteriocin with streptococcin A-FF22 (SA-FF22).

Main Results:

• Anaerobic incubation induced bacteriocin production in 28% of M-type 49 strains.
• A novel bacteriocin, SA-M49, was isolated and characterized as a heat-stable proteinaceous molecule (approx. 8000 Da).
• SA-M49 exhibited identical inhibitory spectra and cross-immunity to SA-FF22.
• SA-M49 production was consistent within outbreaks and useful for differentiating strains of phage subtypes II, III, and VI.

Conclusions:

• Anaerobic conditions are crucial for detecting bacteriocin production in certain M-type 49 group A streptococci.
• SA-M49 is a distinct bacteriocin with properties similar to SA-FF22.
• Bacteriocin P-typing under anaerobic conditions can serve as a valuable tool for epidemiological surveillance and strain discrimination of M-type 49 GAS.