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Toxinogenic Bacillus pumilus and Bacillus licheniformis from mastitic milk

T Nieminen1, N Rintaluoma, M Andersson

  • 1Department of Process and Environmental Engineering, POB 4300, FI 90014 University of Oulu, Finland.

Veterinary Microbiology
|July 6, 2007
PubMed

Insights

Heat-stable toxin-producing Bacillus pumilus and Bacillus licheniformis were found in mastitic cow milk in Finland. These bacteria pose a potential food safety risk in the dairy production chain.

Area of Science:

  • Microbiology
  • Food Safety
  • Veterinary Science

Background:

  • Mastitis is a significant concern in dairy herds.
  • Bacillus species are known contaminants in food and environmental samples.
  • Some Bacillus species produce toxins that can affect food safety.

Purpose of the Study:

  • To identify heat-stable toxin-producing Bacillus strains in mastitic cow milk.
  • To characterize the nature and effects of the toxins produced.
  • To assess the food safety implications of these findings.

Main Methods:

  • Screening of 100 milk samples from mastitic cows.
  • Isolation and identification of Bacillus species.
  • Sperm cell motility inhibition assay for toxin detection.
  • Heat stability and solubility tests of toxins.
  • Polymerase Chain Reaction (PCR) for toxin synthetase genes.
  • Ribotyping for strain comparison.

Main Results:

  • Bacillus was the major organism in 23% of samples.
  • Six toxinogenic Bacillus isolates were identified: four Bacillus pumilus and two Bacillus licheniformis.
  • The toxins were heat-stable, non-proteinaceous, and disrupted sperm cell membrane permeability.
  • Bacillus licheniformis strains contained lichenysin synthetase genes.
  • Ribopatterns matched known food poisoning and indoor air contaminants.
  • Bacillus pumilus and Bacillus licheniformis can survive pasteurization as spores.

Conclusions:

  • Heat-stable toxin-producing Bacillus pumilus and Bacillus licheniformis are present in mastitic cow milk.
  • These spore-forming bacteria pose a potential food safety risk throughout the dairy production chain.
  • Further investigation into control measures is warranted.

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