Microbiology –Chapter 24 – Microbial symbioses with humans
Microbiome; functional collection of different microbes in an environmental system
Microbiota (phyla); the types of organisms present in an environmental habitat
Human microbiome; different microbiota that colonize different habitats of the body
24.1 Overview of the human microbiome
Each body site tends to be dominated by one
population type.
24.2 Gastrointestinal microbiota
The stomach and small intestine
The stomach; very low pH, normally a low pH
prevents bacteria form overgrowth. In the stomach a
core (kern) microbiome is hold.
The small intestine has 3 distinct;
• Duodenum; adjacent to the stomach.
It is acidic.
• Jejunum; pH become less acidic and
bacterial numbers increase.
• Ileum; more anoxic (zuurstofloos)
The large intestine
The aerobes consume any remaining
oxygen rendering the large intestine strictly
anoxic.
The number of anaerobes is enormous.
In the intestine are next to enormous numbers bacteria also
large number of Archaea present.
Bacterial diversity of feces (ontlasting);
Generally, 3 phyla dominate;
• Bacteroidetes
• Firmicutes
• Proteobacteria
Individuals can have >90% Bacteroidetes or >90% Firmicutes, this influence aspects
of their health.
Gut enterotypes
Three general gut communites (enterotypes)
• Bacteroides
• Prevotella
• Ruminococcus
Each enterotype is functionally distinct, for example they differ in their capacity for
vitamin production.
So, the enterotype influence individual health.
Microbiome; functional collection of different microbes in an environmental system
Microbiota (phyla); the types of organisms present in an environmental habitat
Human microbiome; different microbiota that colonize different habitats of the body
24.1 Overview of the human microbiome
Each body site tends to be dominated by one
population type.
24.2 Gastrointestinal microbiota
The stomach and small intestine
The stomach; very low pH, normally a low pH
prevents bacteria form overgrowth. In the stomach a
core (kern) microbiome is hold.
The small intestine has 3 distinct;
• Duodenum; adjacent to the stomach.
It is acidic.
• Jejunum; pH become less acidic and
bacterial numbers increase.
• Ileum; more anoxic (zuurstofloos)
The large intestine
The aerobes consume any remaining
oxygen rendering the large intestine strictly
anoxic.
The number of anaerobes is enormous.
In the intestine are next to enormous numbers bacteria also
large number of Archaea present.
Bacterial diversity of feces (ontlasting);
Generally, 3 phyla dominate;
• Bacteroidetes
• Firmicutes
• Proteobacteria
Individuals can have >90% Bacteroidetes or >90% Firmicutes, this influence aspects
of their health.
Gut enterotypes
Three general gut communites (enterotypes)
• Bacteroides
• Prevotella
• Ruminococcus
Each enterotype is functionally distinct, for example they differ in their capacity for
vitamin production.
So, the enterotype influence individual health.
