5. Probiotics

• Probiotics


  Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host
• Probiotics (etymology)

  From Latin "pro" meaning "for" and "biotikos" meaning "fit for life", referring to "beneficial bacteria"
• History of probiotics

  1. Early 1900s - Russian scientist Elie Metchnikoff proposed acid-producing bacteria in fermented milk could prevent "fouling" in the large intestine

  2. 1930s - Japanese scientist Minoru Shirota developed fermented milk product Yakult

  3. 1965 - Lily and Stillwell coined the term "Probiotics"
• Characteristics of probiotics

  • Non-pathogenic and non-toxic
  • Should have anti-carcinogenic activity
  • Able to produce lactic acid
  • Should stimulate the immune system
  • Resistance to gastric acidity
  • Antimicrobial activity against pathogenic bacteria
  • Adherence to gut epithelia
• Phenotypic identification of probiotic strains

  1. Isolating based on Gram-positive and catalase-negative properties

  2. Testing for acid and bile resistance

  3. Assessing technological characteristics and beneficial effects
• Genotypic identification of probiotic strains

  1. Molecular identification using 16S rRNA marker gene

  2. 16S rDNA sequence analysis and comparison with databases

  3. Whole-genome shotgun sequencing and metagenomic classification
• Modes of action of probiotics

  • Competitive exclusion - compete for nutrients, take up space, block adhesion sites for pathogens
  • Production of antimicrobial compounds - bacteriocins, hydrogen peroxide, short-chain fatty acids, organic acids
  • Immunomodulation - activate immune cells, influence cytokine production
  • Improvement of gut epithelial barrier - increase tight junction proteins, regulate apoptosis
  • Production of neurotransmitters - serotonin, GABA
• Probiotics have been shown to have numerous health benefits, including maintaining a healthy gut microbiome and improving immune function