Food Microbiology

• Clostridium botulinum is a bacteria that produces a toxin that can cause botulism, a severe form of food poisoning, and is often found in improperly canned or preserved foods.
• People have practiced food microbiology for thousands of years, like preserving fish by adding salt and hanging it to dry, making it edible even after several days
• Water availability and feed safety are crucial for organism growth and animal consumption
• Development of microbiology began late, initially focusing on zoology and botany, but later expanding to include other kingdoms like protists, fungi, and bacteria/monera
• Timeline of significant events in food microbiology:

  • 8,000 to 10,000 years ago: food preservation
  • 4,000 years ago: fermented foods intentionally attacked by microbes for preservatives or flavor
  • 1600s: early microscope observations
  • 1700s: challenging spontaneous generation
  • 1800s: Golden Age of Microbiology with cell theory, germ theory of diseases, and more
• John Snow in 1849 emphasized sanitation and observed cholera spread through contaminated water, leading to the isolation of waterborne pathogens
• Foodborne pathogens like Salmonella, Staphylococcus aureus, and Clostridium botulinum were discovered in the late 19th century, with principles like Koch's postulates guiding their identification
• Principle of petri dish: prevents contamination through convection, making it difficult for microbes to enter
• In the field of food microbiology, the invention of monoclonal antibodies in 1980 laid the foundation for mass-produced antibody-based tests
• The first recognized outbreak of listeriosis occurred in 1980
• E. coli O157:H7 was first recognized as a pathogen in 1980
• The first genetic probe for the detection of Salmonella was developed in 1980
• PCR was invented in 1980
• Prions were discovered in 1980
• In 1990, irradiation was approved for pathogen control in meat and poultry
• The mad cow disease crisis hit the United Kingdom in 1990
• HACCP was required by the US Department of Agriculture in 1990
• In 2000, irradiation was approved for shell eggs
• Regulatory concerns about bioterroristic contamination of food led to new laws on facility registration, product traceability, and prenotification of imports in 2000
• The first bioterrorism attempt involved the use of Bacillus anthracis (spore former)
• The sending of letters (snail mail) with powdered pathogens occurred in 2000
• The first report of mad cow disease in the United States was made in 2000
• Common techniques used in food microbiology include:

  • Techniques in general microbiology are also useful in food microbiology
  • Pure culture technique
  • Microscopy
  • Staining, especially Gram stain
  • Sterile microbiological media (liquid and solid)
  • Aseptic technique
  • Methods to control microbial growth
  • Biochemical tests
• Limitations of microbial techniques:

  • Most microbes do not grow in the laboratory
  • Microbes do not grow in isolation
  • Most microbes have not even been discovered
• Advanced techniques in microbiology include:

  • Rapid identification techniques/machines for rapid ID
  • Advanced techniques in the use of genetic materials for analysis
  • Antibody-antigen interactions
  • Advanced microscopy
  • Omics technology
• Developments in food microbiology:

  • Fermentation/probiotics
  • Making fermenting strains more stable
  • Understanding probiotics and their effect on the body
  • Food spoilage
  • Foodborne pathogens
• Food spoilage:

  • Main goal is to avoid food spoilage
  • Waste
  • Which microbes cause spoilage and under what conditions
  • Metabolites
  • How do they work in modified temperatures
  • How can they be controlled
• Foodborne pathogens:

  • Detection
  • Identification
  • Control
  • Monitoring and sharing information
  • Are we making the problem worse
• Topics in food microbiology:

  • Bacteria
  • Fungi (yeast and molds, NOT mushrooms)
  • Viruses
  • Protozoans (parasites), algae, helminths (worms)
• Food Microbiology includes bacteria, fungi (yeast and molds), viruses, protozoans, algae, and helminths (worms)
• Viruses and prions can be foodborne and play an important role in food microbiology
• Prokaryotes (bacteria and archaea) are smaller in size, lack a nucleus and membrane-bound organelles, while eukaryotes (Plantae, Animalia, Fungi, Protista) are larger and have these structures
• Yeasts are single-celled fungi like Saccharomyces cerevisiae used in fermentation, while molds are multicellular structures that can produce toxins, like aflatoxin found in peanuts
• Viruses infect cells, can cause diseases, and interfere with food processing, like bacteriophages infecting bacteria used in fermentation
• Protozoans, algae, and helminths can also be found in food, with protozoans causing parasitic diseases, algae producing toxins, and helminths being parasites like roundworms and tapeworms
• Bacteria classification includes criteria like Gram staining, morphology, metabolic products, and growth conditions, with traditional and modern food preservation techniques used to ensure food safety
• Common abbreviations related to food safety include GHP, GMP, HACCP, FBI, PHF, FIFO, BBD, and GM
• A food microbiologist should know the characteristics of different microbes, how to identify and enumerate them, factors affecting their growth, fermentation vs. spoilage, how microbes cause disease, how to preserve food items, and food safety and security