9: Gut Microbiota Flashcards
Why is the gut also considered a part of the nervous system
Can transmit signals from the gut to the brain
How many species are there approximately in the gut microbiota and how much weight do they contribute?
1000-3500 species contributing 3-5 pounds
When does a baby inherit its first gut flora? How long does it approximately take for a baby’s immune system to fully develop?
At birth from the mother:
- as baby comes through birth canal it swallows first mouthfuls of bacteria
- babies delivered in Caesarian have microbiota of the maternal skin community
Breast feeding continues the process and it takes ~2 years for babies immune system to fully develop
Name seven factors that influence the gut microbiota, how much of the microbiota is shared amongst humans?
About 1/3 is shared
- Environment inputs accounts for ~25% of differences, including animals in the house, rural (reduced risk of inflammatory/respiratory diseases)/urban upbringings, etc
- Age
- Genetic
- Diet and drugs (including medication)
- Diseases
- Travel
- Hormonal cycles
Settle differences have can have a big impact on individual risks of certain conditions
How does our microbiota change as we age? When does the maturation of microbiota into an adult-like configuration occur?
- Strains change
- Higher diversity in adults
Maturation of the microbiota into an adult-like configuration happens during the first 3 years of life
How does our microbiota change as we age? When does the maturation of microbiota into an adult-like configuration occur?
Strains change and there is a higher diversity in adults.
Maturation of the microbiota into an adult-like configuration happens during the first 3 years of life
Name three harmful bacteria, what are their four ‘actions’ and two effects on the body?
Clostridium perfringens, staphylococcus, E.coli (toxic strain)
Actions: intestinal putrefaction, production of bacterial toxin AND carcinogenic substances, gas production
Health inhibition, trigger of disease and promotion of aging
Name two beneficial bacterias. What are their four ‘actions’ and two effects on the body?
Bifidobacteria and lactic acid bacteria
Actions:
- Vitamin synthesis
- Digestion and absorption assistance
- Infection prevention (prevents colonization of pathogens)
- Immunity stimulation (~83% of immunity is located in the gut wall - any change in our balance of beneficial flora will have an immediate impact on the immune system)
Health maintenance and anti-aging
Name three opportunistic bacteria, what is their effect on the body?
Bacteriodetes, E.coli (nontoxic strain), streptococcus
No trouble when healthy but can have adverse actions inside the intestines when the body is weak
How does the variation/amount of bacteria change throughout the GI tract and why?
Very few bacteria in the stomach and more bacteria in the colon due differences in pH, oxygen
What is unique about the appendix? What kind of bacterium are particularly found here and what happens if the appendix becomes blocked?
Has a niche microenvironment and many microorganisms are found here, particularly anaerobes. If the appendix is blocked there’s an increased rate of replication of the anaerobic bacteria which Increases the risk of getting appendicitis.
Name three diseases that nontoxic strains of E.coli been proven to help prevent
Cholera, shigella, pseudomonas infections
What are probiotics and where can they be found?
Organisms (such as bacteria or yeast) that are believed to improve health and are available in supplements and food!
When did the concept that not all bacteria was disease causing occur and why?
Louis Pasteur discovered that fermentation by lactic acid were beneficial as they helped protect food from spoiling. He demonstrated that the lactate produced during fermentation inhibited the growth of pathogens
How was it proven that lactic acid bacteria could inhibit putrefaction/production of toxins in the gut?
It was discovered that bifidum in the fecal samples of breast fed infants could help prevent babies from developing diarrhea. Further investigations showed a link between gut flora (including the bacteria we ingest in food) and mental capacity (senile degeneration).
Thus, it was proven that the bacteria contained in fermented food were important in preventing harmful growth of bacteria and had a beneficial effect on the gut.
Name four ways that antibiotics can negatively effect the gut. What type of antibiotic can have the most detrimental effect, and which pathogen is most commonly seen once antibiotics have been introduced to the gut?
Broad spectrum antibiotics clear the largest number/variety of bacteria in the gut. With antibiotic use they commonest pathogen to appear is Clostridium difficile
- Can alter the number of gut bacteria which can reduce ability to digest
- Can cause diarrhea by directly irritating the bowel (changing balance of gut flora allows pathogenic bacteria to grow)
- Creates antibiotic resistant bacteria in the gut
- Can reduce the influence of probiotics as they rely on a few strains of good bacteria
Which three types of toxins does C.diff produce? Describe how these toxins breaks down the structure of gut epithelia (which in turn damages their function)
Toxin A, B and C
Toxin A/B are main virulence factors: they bind to cell membrane receptors and are internalized, they then use the endosomes to translocate into the cytosol. Within the cell they’ll cause inactivation of proteins which disturbs the organization of the cytoskeleton of the gut cell. It induces apoptosis and inflammation
Toxin C: deactivation of actin thereby changing the way the microtubule formation
Other than antibiotics, name 9 factors that can damage the gut flora
- Drugs (including alcohol, steroids, the pill)
- Poor diet
- Bottle feeding
- Pollution
- Stress
- Infections
- Toxic chemicals
- Old age
- Dental procedures
What two main things can gut flora produce that leads to certain pathological disorders? Name four examples of the pathological disorders that can be caused
Toxins and Carcinogens
Sepsis, colon cancer, IBD, Crohn’s
What three major and general ‘conditions’ can harmful intestinal flora cause?
Obesity, inflammation and autism
Name five factors that can cause chronic inflammation of the gut, what complications does this lead to?
Chronic inflammation causes a ‘leaky gut’ due to structural damage. This allows more transport across the gut epithelia which can cause food intolerances, immune abnormalities and autoimmune conditions
- Antibiotics
- Smoking (heavy metal toxicity)
- Birth control pills
- Chlorinated water/food additives
- High homocysteine levels: parasites, yeasts
Describe the relationship being studied between the microbiota and children on the autism-spectrum. What can be concluded from this?
Autistic children have significantly fewer types of gut bacteria and lower amounts of the three critical bacteria: prevotella, coprococcus and veillonellaceae which are important strains in carbohydrate degrading and fermenting. Thus, many autistic children have IBD symptoms which are sometimes alleviated by probiotics.
Therefore, it has been shown that gut microbes can produce bioactive compounds that influence brain function
What was the relationship discovered between gut flora and serotonin?
When mice that had lower levels of bifidum bacterium, their guts made less tryptophan and bile - compounds needed to produce serotonin. Those mice and their descends also had consequently autistic like behaviour.
Other than antibiotics, what tool can be used to prevent harmful gut flora?
Using bacteriophages (found everywhere, i.e; soil, sea water, intestines, etc)
