SOLUTIONS RATED A+
✔✔Small intestine vs large intestine (bacterial growth in GI tract) - ✔✔Small- resemble
stomach (low PH-->acidic)
(less bacteria)
Large-Fermentation vessel
(lots of bacteria!)
✔✔4 Dominant phyla of Human Digestive Tract - ✔✔-Firmicutes
-Bacteroidetes
-Proteobacteria
-Actinobacteria
✔✔Most abundant phyla of Human Digestive Tract?
What they do? - ✔✔Bacteroidetes & Firmicutes (90%)
-Functions remain similar
-Contribute essential nutrients
-Contribute to gut health:
• Trigger expression of genes
• Prime immune system to recognize microbiome as native
• Contribute to development of mucosal barrier
✔✔Obesity: - ✔✔-Obese humans--> more likely to have large pop. of Prevotella &
methanogenic Archaea
-Increased body fat during pregnancy
✔✔What happen during 1st & 3rd trimester in obese women (pregnancy)? - ✔✔-
Enrichment of Proteobacteria & Actinobacteria
✔✔Upper Respiratory Tract: - ✔✔-Staphylococcus
-Streptococcus
-Diphtheroid Bacilli
-Gram (-) Cocci
-Some Pathogens
✔✔Lower Respiratory Tract: - ✔✔Essentially all streptococci
✔✔The Holobiont: + Examples - ✔✔-Assemblage of a host organism & all other species
associated with it.
Ex:
, -Coral reef & its bacterial & algal symbionts
-Human & its microbiome
"Holobiont Blindspot" in research
✔✔Dysbiosis & Diseases: - ✔✔-Disruption of homeostasis between microbiome & host
• Inflammatory Bowel disease
• Type 2 Diabetes
• Asthma
• Dermatitis
• Colorectal cancer
• Kidney stones
• Periodontitis
• Psoriasis
✔✔Dysbiosis and Cancer: - ✔✔20% of tumors are microbial driven
✔✔Food allergies & the microbiome: - ✔✔Food allergies up to 20% over last decade
-Environmental influences:
-Cow's milk allergy (3% all children)
• C-section
•antibiotic use
•formula feeding
•high fat diet
•low fiber diet
-All can lead to dysbiosis
(probiotics are potentially the answer)
✔✔Lactobacillus rhamnosus GG - ✔✔-Isolated in 1983 from adult gut flora
-Used in numerous probiotic studies
-Found increased Firmicutes in sensitive individuals
-Supplementation with probiotic may stabilize the gut flora
✔✔Microbial Ecology - ✔✔Lecture 21
Study of relationship between microbes & their biotic & abiotic environments
✔✔Sergei Winogradsky - ✔✔-He discovered that some bacteria can use inorganic
chemicals
(like ammonia, sulfur, hydrogen sulfide) as an energy source instead of organic
molecules or sunlight.
(chemolithotrophy)
✔✔Nitrosomonas (Sergei Winogradsky) - ✔✔ammonia-oxidizing bacteria