Lecture 22: The Microbe-Human Ecosystem Flashcards
1
Q
Microbiome
A
- All the genes found in one’s microbiota
2
Q
Microbiota
A
- all the microorganisms that live in and on an organism
3
Q
Holobionts
A
- Hosts and microbes that live and evolve together
- each microbial nice is related to a variety of factors such as body location, age, sex, diet and environment
4
Q
Microbiome- development
A
- Microbiota community is not static
- Begins developing at birth and changes as we age
- A stable community of microbes adopted by age 3
- It is important to develop a diverse microbiome
5
Q
Microbiome- development; Early Life
A
- Newborn colonization important.
- Vaginal birth provides
exposure to microbes from the mother’s birth canal, whereas cesarean delivery provide microbe exposure from initial caretakers
6
Q
Bifidobacteria
A
- Transport polymeric sugars found in human breast milk directly across their plasma membrane
- Fermentation of these sugars provides the infant with calories and lowers the gut pH, limiting growth of pathogens
7
Q
Microbiome- development; adulthood
A
- Relatively stable over time
- Only change due to physical or lifestyle changes
- Variable from person to person and at different sites within a person
- Bacteria common to human skin, the intestinal tract, and the other mucosal surfaces include six major phyla:
1. Actinobacteriota
2. Bacteroidota
3. Firmicutes
4. Fusobacteriota
5. Proteobacteria
6. Verrucomicrobiota
8
Q
Skin Microbiota
A
- Environment:
Slightly acidic pH
High concentration of NaCl
Some areas lack moisture
Some bathed in oily
lubricant sebum and
antimicrobial peptides - Some microbes are transient and typically unable to multiply on the skin
- 3 environmental niches:
1. dry
2. Moist
3. sebaceous
9
Q
Respiratory tract
A
- Upper respiratory tract: nostrils, sinuses, pharynx, and oropharynx
- colonized by a diverse group of microbes
- Lower respiratory tract: larynx below the vocal cords, trachea, bronchi, and lungs
10
Q
Staphylococcus epidermidis
A
- nonpathogenic
- Secreting products of fermentation called short chain fatty acids
- Bacterial interference: inhibits growth of pathogens
11
Q
Oral cavity- gastrointestinal tract
A
- Anaerobes: dominant due to the anoxic nature of the space between the teeth and gums
- As teeth grow,Streptococcus parasanguinis attach to enamel surfaces; S. salivarius attaches to the cheeks and gum epithelia and colonizes
the saliva - Produce a glycocalyx and various other adherence factors that enable them to attach to oral surfaces: Contribute to dental plaque
12
Q
Stomach: gastrointestinal tract
A
- acidophiles
- microorganisms may survive: if pass thru the stomach quickly and if ingested with food particles and are resistant to gastric pH
13
Q
Small intestine- gastrointestinal tract
A
3 areas:
1. Duodenum
2. Jejunum
3. ileum
14
Q
Duodenum
A
- contains few organisms due to stomach acid, bile, and
pancreatic secretions; Gram-positive bacteria comprise most of the microbiota
15
Q
Jejunum
A
- Enterococcus faecalis, lactobacilli, diphtheroids, and the yeast Candida albicans found
16
Q
ileum
A
- flora similar to that in colon;
pH becomes more alkaline; anaerobic Gram-negative bacteria and members of the family Enterobacteriaceae become established
17
Q
Large intestine- gastronintestinal tract
A
- one of the most densely packed microbial ecosystems on earth
- gut microbiome has metabolic, immunological, and endocrine roles
18
Q
Genitourinary tract
A
- kidneys, ureter&urinary bladder: free of microbes
- distal urethra: few microbes found
- Vaginal microbes: complex microbiota that changes due to menstrual cycle and acid tolerant lactobacilli predodminate
19
Q
Functional core microbiome
A
- microbes provide the host with a suite of activities required for health and homeostasis
- Provision of vitamin K and B by E. coli
20
Q
Host metabolism
A
- gut microbiota converts food into calories
- fat ppl: higher concentrations of gut bacteria belonging to the phylum Firmicutes compared to bacteria belonging to the phylum Bacteroidota
- Has refocused attention from the individual species in the gut microbiome to the metabolome (products microorganisms secrete)
21
Q
Effect of the Microbiota- Immunity
A
- Antibiotics disrupt the gut microbial community
- Following antibiotics treatment, people are at higher risk of GI tract, yeast infections
- Colonization resistance: competitive exclusion by resident microbes
22
Q
Microbiota regulate host immune system- Immunity
A
- Gut microbes communicate with host via Toll-like receptors (TLRs)
- The more diverse the microbiome, the better the
immune cells will become at
distinguishing between harmful pathogens and harmless bacteria
23
Q
Microbiota regulare inflammation- immunity
A
- Mucosal tolerance: how microbes reside in our gut
without an overwhelming inflammatory response - Balance between pro-inflammatory cells, which
produce the anti inflammatory cytokine IL-10
24
Q
Central Nervous System
A
3 ways microbiome can influence the CNS:
1. Microbiome impacts the immune system
2. Direct pathway from gut to brain through nerves in GI tract which transmit signals to the brain via the vagus nerve
3. Soluble microbial products cross the blood brain barrier
25
Q
Dysbiosis
A
- pathological changes in the gut microbiome that lead to disease
- leads to inflammation
26
Q
Metabolic syndrome
A
- characterized by at least 3 of the following:
1. Large waist circumference.
2. High blood triglyceride level.
3. High blood pressure.
4. Elevated low-density lipoprotein.
5. High fasting blood glucose levels - Linked to the microbiome as explained by metabolic
endotoxemia
27
Q
Probiotics
A
- “Live microorganisms, which, when administered in adequate amounts, confer a health benefit to the host”
28
Q
Prebiotics
A
compounds added to enhance the colonization and positive health benefits of probiotic microbes
29
Q
Metabolic Endotoxemia
A
- known as leaky gut
