Production and properties of crude enterotoxin of Pseudomonas aeruginosa

Area of Science:

• Microbiology
• Food Safety
• Toxicology

Background:

• Foodborne pathogens pose significant public health risks.
• Pseudomonas aeruginosa is an opportunistic pathogen found in various environments, including dairy products.
• Enterotoxin production by bacterial strains can lead to gastrointestinal illness.

Purpose of the Study:

• To identify and characterize enterotoxigenic strains of Pseudomonas aeruginosa from milk.
• To investigate the properties and stability of the enterotoxin produced by P. aeruginosa CTM-3.
• To explore the potential role of plasmids in enterotoxin synthesis.

Main Methods:

• Isolation and screening of Pseudomonas aeruginosa from milk samples.
• In vivo (rabbit gut fluid length ratio) and in vitro (rabbit skin permeability) assays for enterotoxigenicity.
• Plasmid curing using ethidium bromide and assessment of enterotoxin production.
• Thermal stability, pH stability, and enzyme inactivation studies of the crude enterotoxin.

Main Results:

• Pseudomonas aeruginosa CTM-3 was identified as the most enterotoxigenic strain among 12 isolates.
• A high fluid length ratio (1.1) and significant necrotic zone (38.5 mm2) were observed.
• Enterotoxin production was lost in 6 plasmid-cured variants, suggesting plasmid involvement.
• The enterotoxin was inactivated within 15 seconds at 72°C but was stable between pH 4.5-7.5.
• Pepsin and trypsin inactivated the toxin, while organic acids, formalin, and hydrogen peroxide did not.

Conclusions:

• Pseudomonas aeruginosa CTM-3 possesses significant enterotoxigenic potential.
• Plasmid-mediated enterotoxin synthesis is likely in this strain.
• The crude enterotoxin exhibits specific inactivation and stability characteristics, requiring further study with purified preparations.