Lecture Notes: Satic and Protic Fermentation

Overview

• Discussion on satic and protic fermentation.
• Transition from taxonomy (identifying microbes via whole genome sequencing) to function (identifying genes coding for specific functions).
• Importance: Capturing functions from any microbe producing them, independent of specific microbe identification.

Satic vs Protic Fermentation

• Satic Fermentation:
  • Carbohydrate fermentation by commensal bacteria.
  • Produces anti-inflammatory byproducts like short-chain fatty acids (SCFAs) and lactate.
  • Healthy metabolic function.
• Protic Fermentation:
  • Protein fermentation by pathogenic, gram-negative microbes.
  • Produces toxic byproducts (e.g., ammonia, hydrogen sulfide) in large amounts.

Analyzing Fermentation Patterns

• Assess dietary impacts based on levels of fermentation markers:
  • High proteolytic fermentation may indicate high protein/fat diet or poor digestion.
  • Low proteolytic fermentation may suggest insufficient food intake.
• Digestion should occur primarily before reaching the colon.
  • Proper digestion relies on stomach acid, enzymes, and bile.
  • Improper digestion results in undigested food reaching the colon, leading to excessive fermentation by bacteria.

Satic Fermentation Details

• Short Chain Fatty Acids (SCFAs):
  • Butyrate: Key fuel for colonocytes; produced by species like Ruminococcus and Eubacteria.
  • Propionate: Produced by Bacteroides; important for smooth muscle contraction but linked to neurocognitive disorders when elevated.
  • Acetate: Involved in appetite regulation; high levels can affect the liver.
  • Lactate: Modulates immunity and inflammation; balance between producers and utilizers is essential.

Influences on SCFAs

• Balance is crucial for health.
• Glyphosate affects SCFA levels, suggesting diet influences.
• Improving SCFAs involves increasing fiber and polyphenol intake.

Protic Fermentation Markers

• Polyamines: High levels common; linked to poor protein digestion or excess protein intake.
• P-Cresol: Results from tyrosine fermentation; cytotoxic, linked to chronic conditions.
• Ammonia: Byproduct of amino acid fermentation; elevated levels harm brain and liver.
• Hydrogen Sulfide: Produced by bacteria like Bilophila wadsworthia; associated with digestive issues and neurocognitive disorders.
• Methane: Produced by archaea; linked to constipation and weight gain.

Managing Fermentation Issues

• Consider dietary adjustments (e.g., plant-based proteins) and support digestive processes.
• Addressing gut microbiome imbalances and improving digestion can reduce toxic byproduct production.