Topic 19: Microbes, Food and Nutrition

Question 1

Describe the benefits of microbes in soil, plants and animals

Answer 1

• Soil: maintain soil health
  + Fix nitrogen to produce NH4+ for plants
  + Break down organic wastes into inorganic nutrients (decomposition)
  + Supressing other pathogens
  + Break down toxins
• Animals: allow animals to digest cellulose
  + Cellulose: abundant in plants, carbon-rich, sugar polymer → hard to digest
  + Rumen microbes break down cellulose into sugars then organic acids, CO2 and CH4
  + The products are consumed as nutrients
• Plants: mutualism → promote plant growth; for example
  + Mycorrhizal fungi: most plants
  + Improves water and nutrients uptake of plants
  + Receives sugars
  + Rhizobium bacteria: in legumes roots
  + Fix nitrogen → NH4+ → nutrients for plants
  + Receive sugars

Question 2

Describe the downfalls of microbes in plants and animals

Answer 2

• Fungi and viruses are main issues in plant diseases.
  e.g Sigatoka fungi threatens existence of bananas
• Viruses, bacteria, fungi or protists can all be pathogens to animals
  → great loss in suffering, death and huge economic losses
  e.g Foot and Mouth disease affected lots of livestock
• Animals-infected diseases can be transferred to humans → zoonosis
  • Microbes can be pathogenic to both humans and animals or
  • Human pathogens may be normal flora in animals → when transferred, human body cannot tolerate that or
  • Animals are vector for disease spread

Question 3

Describe the role of microbes in fermentation, food processing and storage

Answer 3

• Food processing: enhancing flavour
  + Fermentation: by fungi or bacteria
  - Anaerobic metabolism of plants → alcohols
  - Crucial in lots of products
• Suitable conditions (like temperature) to prevent microbial growth

Question 4

Describe food spoilage and poisoning

Answer 4

• Spoilage: either
  
  • growth of fungi and bacteria, or
  • enzymes that microbes secrete
• Food poisoning: can be from spoiled or fresh food; induced by microbes different from in food spoilage
  
  • Food-borne infection: ingestion of alive microbes which then grow in GI tract → due to toxin infection
  • Food-borne intoxication: microbes produce toxins in food → ingestion of microbial forms of toxins

Question 5

What are some factors resulting in food poisoning?

Answer 5

• Origins of food (plants or animals)
• Inappropriate storage or processing
• Human factors: hygiene

Question 6

Describe the gut microbiome and its role health

Answer 6

• Healthy gut microflora/microbiome: most important part in normal flora
  
  • MOSTLY BACTERIA
  • Mostly bacteriodetes in high fibre diet and firmicutes in high protein & fat diet
  • Nutritional benefits from assistance in food digection (esp. fiber)
  • Pathogens resistance by competing and occupying space and nutrients
  • Immune functioning by training immune cells to recognize foreign pathogens

Question 7

What can imbalanced gut microbiome result in?

Answer 7

Chronic diseases like allergies, T2D, cancer, obesity, etc.