9.1 Gut Bacteria Flashcards
Give 4 beneficial functions of Microbiota in our gut
1) aids digestion of foods that we are unable to
2) production and transport of vitamins, minerals and nutrients
3) synthesises nutrients eg. K2, B vitamins and some amino acids.
4) defence from microorganisms
5) maintains integrity of the intestinal mucosa
6) helps to chelate heavy metals from our system
What bacteria is considered dominant in our gut microbiota?
Give 3 features of this bacteria
Bacteroides
- gram-negative
- obligate anaerobic bacteria
- non endospore-forming bacilli
List 4 key factors that can influence our microbiome
1) age
2) diet
3) hormonal cycles
4) travel
5) medication
6) Illness
Where do we inherit our gut flora from initially and how?
We inherit our gut flora from our mother at birth
As the baby comes through the birth canal it swallows its first mouthfuls of bacteria, which begin to inhabit baby’s sterile gut
Babies that were delivered normally are dominated by what bacteria(s)
Lactobacillus
Prevotella
Atopobium
Babies that were delivered by cesarean section are dominated by what bacteria(s)
microbiota that is of the maternal skin community
eg. Staphylococcus
After we inherit microbiota from birth what process continues development of microbiota?
How long does it take a babies immune system to fully develop?
breast feeding ➞ takes about 2 years for baby immune system to full develop
What bacteria is related to carbohydrates and simple sugars
Prevotella
What bacteria is associated with animal proteins, amino acids and saturated fats
Bacteroides
What can be said about gut microbiota with age (3)
1) Number of microorganisms decrease as we reach older age
2) The strains and dominant bacteria change throughout ageing
3) Diversity of microbiota composition is higher in adults than children
When does the maturation of microbiota into an adult- like configuration happen?
During the three first years of life
Give 3 factors at birth/early life that influence your gut bacteria
1) were you born sterile
2) how were you born? (natural or C-section)
3) were you breast fed or bottle fed?
What are the four dominant phyla in the human gut
1) Firmicutes
2) Bacteroidetes
3) Actinobacteria
3) Proteobacteria
Give 2 other bacteria that are commonly present (not the 4 dominant phyla)
Escherichia and Lactobacillus
Give a common probiotic bacteria that can be found in our gut
Describe the structure of this and where specifically is it located
Bifidobacterium bifidum ➞ gram + bacilli of large intestine
Describe the structure of E.coli and where in the GIT it is found
How is it beneficial in the gut?
List one infection E.Coli cannot protect against
E. coli is a gram negative, rod-shaped, facultatively anaerobic bacteria of large intestine
Plays a huge role in prevention of infections by other bacteria, in particular shigella, cholera and pseudomonas
Not helpful in Candida infections
Give 2 gram positive bacteria found in the gut, include their shape and O2 use
Clostridium perfringes- rod-shaped and anaerobic
Peptostreptococcus anaerobius: cocci and anaerobic
Give 2 bacteria that are of the phylum: Firmicutes
Clostridia and Lactobacilli
Give a bacteria that is of the phylum: Bacteroidetes
Bifidobacteria
Give 2 examples of “beneficial bacteria”
What Is their action?
What is their overall effect on the body?
Bifidobacteria and Lactobacteria (lactic acid bacteria)
- vitamin synthesis
- digestion and absorption assistance
- infection prevention
- immunity stimulation
Overall helps to maintain health and considered to be anti-aging
Give 2 examples of “harmful bacteria”
What Is their action?
What is their overall effect on the body?
Clostridium perfringes, Staphylococcus and E.coli (toxic strains)
- intestinal putrefaction
- production of bacterial toxins
- production of carcinogenic substances
- production of gas
Overall can cause health inhibition, trigger disease and promote ageing
Give 2 examples of “opportunistic bacteria”
What is an opportunistic bacteria and what is its effect on the body?
Bacteriodetes, E.Coli (non-toxic strains), Streptococcus
OPs are part of the normal human flora. Under normal conditions they cause no harm and may have a beneficial effect by preventing colonisation by other potential pathogens.
When these bacteria are introduced into anatomical sites where they are not normally found, or competing bacteria are removed by the use of broad- spectrum antibiotics, they may multiply locally and lead to the development of disease
Why are different bacteria found in different areas of the gut?
Because of the physical nature of the gut eg. pH and oxygen distribution
What is special about the appendix?
What type of bacteria are usually found here?
What can happen if the appendix gets blocked?
The Appendix has its own niche microenvironment that harbour many species of particular microorganisms that are only found here ➞ normally anaerobes
If appendix gets blocked, we get an increased rate of replication of these anaerobic bacteria. This can increase risk of developing appendicitis
What are our “indigenous friendly bacteria”?
Give an example of 4
These are essential or beneficial flora (also known as a probiotic)
Bifidobacteria, Lactobacteria, Peptostreptococci, Enterococci
What can be said about imbalances to our beneficial flora and development of disease?
Why is this the case?
Changes to balance of our beneficial microflora will have an immediate impact on immune system. This significantly increases our risk in developing diseases
Around 83% of our immunity is located in the gut wall and this microflora play a crucial role in keeping immunity active
What is the definition of a Probiotic?
Probiotics are organisms such as bacteria or yeast that are believed to improve health. They are available in supplements and foods.
Probiotics rely on a few strains of good bacteria
List 3 benefits of probiotics in yogurt
1) introduces vitamins
2) increases satiety (fullness)
3) decreases weight gain
Give 3 harmful effects of antibiotics (in particular broad spectrum) on gut flora
Every time we swallow antibiotics we kill the beneficial bacteria within our intestines
1) can alter the numbers of gut bacteria, which can reduce ability to digest
2) can cause diarrhoea by irritating the bowel directly, changing the levels of gut flora, and allowing pathogenic bacteria to grow
3) creates antibiotic resistant bacteria in gut
What is the danger of Clostridium difficile + give its MoA
Produces 3 toxins: A,B,C (NOT an A-B toxin) that significantly disrupt the structure of the gut cells causing disruption to function
1) A and B toxin bind to cell surface receptors allowing internalisation (main virulence factors)
2) they use the host endosomes to translocate into the cytosol
3) once toxins are in the cell they cause inactivation of growth proteins proteins which disrupt the structure of the cytoskeleton
4) toxin C will then bind to _____ causing _____ thus altering microtubule formation
4) they also Induce apoptosis and inflammation
Give 6 harmful agents that can damage microflora
antibiotics poor diet bottle feeding alcohol steroids the OCP stress Infections old age radiation
List 4 common conditions though to be caused or effected by gut dysbiosis
1) UC
2) colon cancer
3) IBD,
4) Crohn’s
5) sepsis and multi-system organ failure
How may gut dysbiosis lead to the formation of a tumour?
Harmful gut flora can produce toxins and carcinogens which can result in infection and inflammation
Chronic inflammation in the gut involves a repetitive cycle of damage and repair
Neoplasms can occur through this process during repair of damaged tissue along with initiation by the carcinogenic metabolites
Can result in tumour development
How may chronic inflammation due to gut Dysbiosis effect the intestinal epithelium?
What can this progress to?
Can lead to a “leaky gut” due to loss of structure. This allows more transport of substances across the intestinal epithelia
A leaky gut can progress to food intolerances -> immune abnormalities -> autoimmune conditions
Give 4 causes of chronic inflammation which can lead to a leaky gut
1) poorly digested food-alcohol
2) antibiotics or infection-painkillers
3) birth control pills and antacids
4) chlorinated water-food additives
5) heavy metal toxicity-smoking
6) high homocysteine levels (due to parasites, yeasts food allergies)
What could be a possible therapy against multi-drug resistance strains of bacteria?
What is this?
Using a bacteriophage: this is a virus that infects and replicates within bacteria, killing them
Explain what the twin study involving mice showed about gut microflora
The microbiota from an obese twin and a lead twin were taken and given to two lean mice that were both on the same diet
Results showed that the mouse that received the transplant from the obese twin had increased adiposity and the mouse that that received transplant from the lean twin, maintained their lean figure
What is stress?
What biological changes to the body occur during stress
Stress is a person’s response to a stressor (a stimulus) Stress is a body’s way to react to a challenge in a flight or fight situation
1) Blood pressure rises
2) Breathing becomes more rapid
3) Digestive system slows down
4) Heart rate (pulse) rises
5) Immune system goes down
6) Muscles become tense
7) We do not sleep (heightened state of alertness)
What hormone is responsible for stress?
List the mechanism that triggers its release
Cortisol:
Hypothalamus ⬇ CRH Anterior pituitary ⬇ ACTH Adrenal cortex (zona fasciculata- glucocorticoids) ⬇ Cortisol
Cortisol negatively feedback to both the anterior pituitary and the hypothalamus to control secretion (in times of stress levels will be elevated)
What is Parkinson’s disease and what is its cause?
Which probiotic may be beneficial in treating this?
A degenerative condition causing tremor and motor impairment, caused by loss of dopamine-secreting neurons
Bacillus spp. produce dopamine
What can be said about levels and types of gut bacteria that have been found in children with Autism?
What does this commonly lead to the development of in Autistic children?
Autistic children have significantly fewer types of gut bacteria and significantly lower amounts of three critical bacteria:
Prevotella, Coprococcus and Veillonellaceae
These three bacterial groups represent important strains of carbohydrate degrading and fermenting microbes. So, many autistic children have IBD symptoms (found to be managed by application of probiotics)
