Last ppt Flashcards
How dense is the population of the oral cavity microbiom?
Very densely populated
Does the entire mouth contain the same uniform type of microflora?
No, differeent regions are colonized by different types of bacteria
How much of the microflora in the oral cavity has not been established?
Half! Very complex
How is the skin’s microbiome distributed?
Thinly spread out over large surface area
What type of bacteria is skin microbiome dominated by?
Gram +
What part of the urinary tract is not sterile?
distal region of urethra
How is the vaginal microflora populated?
Densely
What is the predominant bacteria in vaginal microflora?
lactobacilli
What is the microflora of the upper respiratory tract like?
Complex
What is the composition of the uper respiratory tract’s microflora dependent on?
Anatomical site
How are the microflora of the lungs and internal tissues similar?
normally sterile
What 4 parts is the GI tract made up of?
Stomach, duodenum, jejunum, colon
What is the population density of the colon versus the stomach?
Stomach: sparcely populated
Colon: very densely populated
Which part of the human body contains most of the bacteria inhabiting humans? How much?
GI Tract
10^14
What are commensals?
Microorganisms normally found on healthy individuals
Do commensals cause infection?
No, commensals colonize the body without infecting it
How many microbes are on the skin?
10^12
How many microbes are in the mouth?
10^10
How many microbes are in the GI tract? What is the weight equivalent?
10^14
1 kg
Where are most of the GI tract’s microbes located? What %? Aerobic or anaerobic?
Colon
90%
Anaerobic
What 4 factors influence the richness and abundance of microorganisms on an individual?
- Temp
- pH
- Nutrient supply
- Immune system (genetic factor)
In what 3 ways can commensals be beneficial?
- provide host with vitamins and metabolic pathways (gut)
- Protect against new incoming microbial populations (guard their territory)
- Teach the immune system
Do all animals contain the same commensals?
No, commensals in one animal’s body may harm a different animal
Can commensals become parasitic/pathogenic?
Yes under specific conditions
What are pathogens?
Microbial parasites that are unable to cause infection
What is an infection?
A situation in which a microorganism is established and growing in a host, causing damage.
What is a disease?
Damage or injury to the host that impairs host function
What is pathogenicity?
ability of a parasite to inflict damage to the host
What is virulence?
measure of pathogenicity
What are opportunistic pathogens? Does the normal microbiom contain opportunistic pathogens?
Ones that cause disease only in the absence of normal host resistance.
yes
What are herbivores? Carnivores? Omnivores?
Animals that consume mostly plants.
Animals that consume mostly meat.
Animals that consume both.
What do phylogenetic studies suggest about herbivores?
Different lineages evolved a herbivorous lifestyle
What are two glucose residues next to one another in cellulose called?
Cellubiose
What do herbivores live off of? What are 4 of the insoluble polysaccharides that they eat?
Plant material rich in:
- Cellulose
- Lignin
- Hemicellulose
- Pectin
What enzyme do animals lack that plants have?
Cellulase
What two digestive strategies have evolved in herbivorous animals?
Foregut fermentation
Hindgut fermentation
What is the location of the fermentation chamber in foregut fermentation?
before the acidic stomach (in rumen?)
What does Hindgut fermentation use as fermentation chambers?
Cecum and/or large instestine
What are 4 examples of types of animals that are foregut fermenters?
Ruminants (cows), colobine monkeys, macropod marsupials, hoatzin
What are 4 examples of hindgut fermenters?
Cecal animals, primates, some rodents, some reptiles
What happens to food from the moment it enters a foregut fermenters mouth?
Chewed minimally, swallowed, and passed into the rumen
What is the volume of a cow’s rumen? A sheeps?
100-150L
6L
What is the temperature of the rumen? pH?
39-40 Celcius
5-7
Is the inside of the rumen aerobic or anaerobic?
Anaerobic
How is the pH of the rumen maintained?
Saliva which contains sodium bicarbonate and sodium phosphate
How much of the rumen’s microorganisms produce cellulase?
Only a small poriton
What is fermentation in the rumen mediated by?
Cellulolytic microbes
How do cellulolytic microbes break down cellulose?
They hydrolyze it into free glucose and cellobiose which is then available to all microorganisms for growth
What happens to the sugars (glucose) that the cellulolytic microbes broke down?
The sugars (glucose) are then fermented which produces volatile fatty acids, CH4 and CO2.
What are 3 examples of volatile fatty acids?
Acetic acid, propionic acid, butyric acid
How do the volatile fatty acids leave the rumen? What are they used as by the animal?
They pass through the rumen wall into the bloodstream. Used by the animal as main energy source
Rumen microorganisms contain how many microbes/g of rumen content?
10^10-10^11 microbes/g
What types of microorganisms inhabit the rumen?
ciliated protozoa, bacteria, archea
What is an example of a rumen microorganism?
Ruminococcus
What do methanogens produce?
CH4
What type of microorganism are methanogens?
Strict anaerobes
What are the 2 net reactions for methanogens?
- 4H2 + CO2 –> CH4 + 2H2O + energy
2. CH3COOH –> CH4 + CO2 + energy
What is CH3COOH?
Acetate
What is the acetate used by methanogens not available to?
The host
What % of the energy value of a rumenant’s feed can be lost as CH4?
10%
What is added to feed reduce production of CH4? What does it inhibit?
Monensin. Inhibits methanogenesis
What happens several hours of microbial digestion?
Small portions of the rumen contents are regurgitated, well chewed and then swallowed again as smaller food particles.
Where do the re-swallowed smaller food particles go?
Reticulum –> omasum –> abomasum (stomach) –> intestines
What else is collected at the omasum along with the smaller food particles?
Excess water
The mass of microbial cells are subject to what? They serve as a source of what?
Digestion.
Major source of amino acids and vitamins.
Where does fermentation take place in non-ruminant herbivores? What does the fermentation provide?
Caecum.
Provides organic acids absorbed by the animal
Non ruminant herbivores posses what type of fermentation chamber?
Hindgut
What happens to the microbial mass that grows on cellulose in non-ruminant herbivores? What is the result of this in terms of their diets?
Not digested. Excreted.
They have higher dietary requirements for amino acids and vitamins than ruminants.
How have rabbits and hares adapted to the non-ruminant herbivore requirement for more a.a.’s and nutrients?
They eat their poop (fecal pellets)
What is the action of eating feces called?
Coprophagy
The Hawaiian bobtail squid has a symbiotic realtionship with what microorganism? What is a unique characteristic of this microorganism?
The marine bacterium: Aliivibrio fischeri.
Biolumunescent!!! :)
How does the squid form this symbiotic relationship with Aliivibrio fischeri?
The squid is home to large populations of A. fischeri in a specialized light orange structure. The bacteria emits light that looks like moonlight penetrating marine waters, camouflaging the squid from predators.
The transmission of the bacterial cells between the squid and the A. fischeri is done how?
Horizontally
What do termites decompose?
Cellulose and hemicellulose
Are the microorganisms in termites anaerobes or aerobes?
Cellulotic anaerobes
Termites belong to what family?
Ruminococcaceae
Relative to one another, how many of the human microbes contribute to health, and how many are harmful?
few, fewer
Human microorganisms are usually found associated with what?
Human body tissue
When are humans colonized by microorganisms?
Birth (vagina)
What are 5 factors that can affect any human’s microbiome?
- diet
- environment
- age
- sex
- occupation
What is the epidermis (outer skin layer) composed of?
An inner layer of living & actively replicating cells + an outer layer of dead cells
What 3 types of glands secrete salt water?
Are these secretions more acidic or basic?
What is in these sweat secretions that allows them to have some antimicrobial effects?
- Sebaceous glands
- Eccrine sweat glands
- Apocrine sweat glands
Slightly acidic
Lipids and proteins
What is the purpose of the outer dead cell layer of the skin?
Tough barrier that prevents microorganisms from penetrating deeper tissue
What is the environment of the skin like? Does this support or prevent the growth of microorganisms?
Dry & acidic.
Does not support microbial growth
What are the ducts that carry secretions to the surface of the skin colonized by?
Only a few (gram +) well adapted species
What does the normal microbiome of the skin secrete to the surface?
Bacteriocin that kills incoming competitors and protects against colonization of harmful bacteria
What microorganisms inhabit hair canals?
Propionobacterium acnes. anaerobes (aerotolerant)
What are 3 examples of microorganisms that live in the skin?
- Mycobacterium
- staphylococcus
- streptococcus
What microorganisms predominate in sebaceous skin?
Propinobacteria
What microorganisms predominate in moist skin?
Antinobacteria
What microorganisms predominate in dry skin?
Proteobacteria
Are aerobic or anaerobic niches located in the oral cavity?
Both
What do high concentrations of nutrients near the surfaces in the mouth promote?
Localized microbial growth
The teeth consist of ____ that surround _____.
- mineral matrices
2. living tissue
What is a synonym for mineral matrices in teeth?
enamel
What are two other names for living tissue in the mouth?
Dentin and pulp
How do bacteria first colonize tooth surfaces?
by attaching to acidic glycoproteins deposited there by saliva
What does extensive growth of oral microorganisms result in? What is the main type of microorganism?
dental plaque (thick bacterial layer).
Streptococci
What microorganisms react to sucrose intake in the mouth? How?
streptococcus mutans
they synthesize dextran (extracellular polysaccharides) that helps it attach to the tooth surface
What type of bacterial species begin to grow as plaque continues to develop?
Anaerobic
What microorganisms are present in dental plaque?
S. mutans and various lactobacilli
What do the microorganisms in dental plaque do that leads to cavities?
They ferment sucrose and produce lactic acid that demineralizes the tooth enamel by solubilizing Ca)
What are the 2 major processes in the stomach of humans? pH?
- Secretion of acid (HCl)
- Digestion of macromolecules
- pH 2
What are the 2 major processes in the small intestine of humans? pH?
- Continued digestion
- Absorption of monosaccharides, AAs, fatty acids, water
pH 4-5
What 3 parts is the small intestine made up of?
Duodenum, jejunum, Ileum.
What body part is the large intestine?
Colon
What is the major processe in the large intestine of humans? pH?
Absorption of bile acids and Vit B12
pH 7
How many microbial cells are located in the GI tract of humans?
10^13 - 10^14
When does the colonialization of the GI Tract of humans begin?
At birth
What are the microbial populations in different areas of the GI tract influenced by?
Diet
Physical conditions in the area
What prevents many organisms from colonizing the GI tract?
Acidity of the stomach and the duodenum of the small intestine (~pH 2)
What type of microbes are in the human colon? Examples?
Mostly strict anaerobes or facultative anaerobes.
Bacterioides, enteric bacteria (E. Coli), yeasts, anaerobic protozoa (Entamoeba coli).
What do microorganisms in the human colon digest and what do they produce?
Digest: complex COHs (cellulose, starch)
Produce: volatile FA’s
What do intestinal microorganisms of the large intestine ferment in the human colon? Produce?
Ferment: Volatile FAs
Produce: gas (CO2, H2)
Methanogens are found in the colon of how many adults? What do they convert to methane?
1/3. Convert CO2 and H2 to methane
What type of organisms produce H2S in the human colon?
Sulfate reducers & organisms that can ferment cysteine and methionone
What organisms are responsible for the smell in the human colon? Synonym?
Organosulfur compounds.
Synonym: methanethiol
What do intestinal microorganisms produce after carrying out essential metabolic reactions?
Amino acids & vitamins (B12, K, thiamine, riboflavin, etc)
Microorganisms contribute to the ______ of the GI tract.
“maturing”
What 3 things do microbes in the gut affect?
- early development
- health
- predisposition to disease
How do gut microorganisms play a role in obesity? Lean mice vs Obese mice
Lean mice produced high levels of H2 which retards fermentaion. Low amount of VFAs and nutrients for host.
Obese mice produced low levels of H2 which promoted fermentation and also produced methane from H2. High amount of VFAs and nutrients for host.
The microbiome of what two facial features are very similar? What microorganisms are present here?
Nose and nasopharynx = mouth.
Staphylococci, streptococci, corynebacteria.
Nasopharynx may be home to/harbor what in healthy carriers? What are 3 examples of these potential pathogens?
Potential pathogens that are under control by host immune system.
- Streptococcus pneumoniae
- Haemophilus influenzae
- Neisseria meningitis
What part of the body has historically considered free of microorganisms? This was determined using what technique? What do recent studies show?
The lower respiratory tract (trachea, bronchi, lungs). The culture technique.
Recent studies show that the lower respiratory tract has a low biomass microbiome.
Why are the genitourinary tract of men and the urinary tract of women generally free of microorganisms?
because of the flushing action of urine
How could a change in pH in the urethra cause disease?
By causing potential pathogens to multiply
Which two of the normal microorganisms of the gastrointestinal tract can cause urinary tract infections?
E. coli
Proteus mirabilis
In the vaginal tract, what is the variety and types of organisms dependent on?
Age of the person
Hormones control the _______ concentration of the vaginal _______.
- glycogen
2. epithelium
What do microorganisms degrade in the vaginal tract? What do they produce? How does this affect pH?
Degrade glycogen.
Produce lactic acid.
This reduces the pH of the vaginal tract to 4.5.
What is the [glycogen] in the vaginal tract 1. before puberty 2. when sexually mature 3. After menopause
- low
- high
- low
What is the pH of vaginal secretion 1. before puberty 2. when sexually mature 3. After menopause
- Alkaline
- Acidic
- Alkaline
What is the microbia flora in the vaginal tract 1. before puberty 2. when sexually mature 3. After menopause
- staphylococci, streptococci, coliforms, corynebacteria
- lactobacilli**, streptococci, corynebacteria, candida albicans
- staphylococci, streptococci, coliforms, corynebacteria
What are the 7 normally steril zones in the human body?
- Blood
- Spinal fluid
- Internal portion of urinary tract (bladder, kidney)
- Peritoneal cavity (gut cavity)
- Pleural cavity (lung cavity)
- Sinuses
- Interior region of other body tissues (bones, muscle)
