Studies on Streptococcus faecalis enterotoxin.

Area of Science:

• Microbiology
• Food Safety
• Bacterial Pathogenesis

Background:

• Streptococcus faecalis, now often classified as Enterococcus faecalis, is a known cause of foodborne illness.
• Understanding the characteristics of enterotoxin-producing strains is crucial for food safety.
• Previous research has indicated the potential for S. faecalis to cause food poisoning.

Purpose of the Study:

• To characterize enterotoxin production in S. faecalis strains.
• To determine the enzymatic activity and optimal conditions for the enterotoxin.
• To assess the antibiotic susceptibility of S. faecalis strains and identify mutants with altered toxin production.

Main Methods:

• Six S. faecalis strains were evaluated using Sherman's criteria.
• Enterotoxin was purified using Sephadex G-200 chromatography.
• Enzyme activity was assessed using trypsin and papain.
• Antibiotic sensitivity testing was performed on all strains.
• Mutagenesis was induced using acridine orange and ethidium bromide.

Main Results:

• All tested S. faecalis strains met Sherman's criteria, being non-hemolytic, DNase-positive, and enterotoxin-positive (Ent+).
• The purified enterotoxin showed maximum activity at 37°C and pH 7.0.
• Enterotoxin treated with proteases (trypsin, papain) exhibited reduced fluid accumulation response.
• Antibiotic sensitivity varied among strains.
• Mutagenesis yielded 47 mutants; 4 were toxin-negative, with 3 also being DNase-negative and 1 showing partial DNase activity.

Conclusions:

• The study confirms the enterotoxigenic potential of S. faecalis strains.
• Proteolytic enzymes significantly impact enterotoxin activity.
• Mutagenesis offers a method to investigate the genetic basis of toxin production, with some mutants losing both enterotoxin and DNase activity.