9.1 Gut Bacteria

Question 1

Give 4 beneficial functions of Microbiota in our gut

Answer 1

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

Question 2

What bacteria is considered dominant in our gut microbiota?

Give 3 features of this bacteria

Answer 2

Bacteroides

• gram-negative
• obligate anaerobic bacteria
• non endospore-forming bacilli

Question 3

List 4 key factors that can influence our microbiome

Answer 3

1) age
2) diet
3) hormonal cycles
4) travel
5) medication
6) Illness

Question 4

Where do we inherit our gut flora from initially and how?

Answer 4

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

Question 5

Babies that were delivered normally are dominated by what bacteria(s)

Answer 5

Lactobacillus
Prevotella
Atopobium

Question 6

Babies that were delivered by cesarean section are dominated by what bacteria(s)

Answer 6

microbiota that is of the maternal skin community

eg. Staphylococcus

Question 7

After we inherit microbiota from birth what process continues development of microbiota?

How long does it take a babies immune system to fully develop?

Answer 7

breast feeding ➞ takes about 2 years for baby immune system to full develop

Question 8

What bacteria is related to carbohydrates and simple sugars

Answer 8

Prevotella

Question 9

What bacteria is associated with animal proteins, amino acids and saturated fats

Answer 9

Bacteroides

Question 10

What can be said about gut microbiota with age (3)

Answer 10

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

Question 11

When does the maturation of microbiota into an adult- like configuration happen?

Answer 11

During the three first years of life

Question 12

Give 3 factors at birth/early life that influence your gut bacteria

Answer 12

1) were you born sterile
2) how were you born? (natural or C-section)
3) were you breast fed or bottle fed?

Question 13

What are the four dominant phyla in the human gut

Answer 13

1) Firmicutes
2) Bacteroidetes
3) Actinobacteria
3) Proteobacteria

Question 14

Give 2 other bacteria that are commonly present (not the 4 dominant phyla)

Answer 14

Escherichia and Lactobacillus

Question 15

Give a common probiotic bacteria that can be found in our gut

Describe the structure of this and where specifically is it located

Answer 15

Bifidobacterium bifidum ➞ gram + bacilli of large intestine

Question 16

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

Answer 16

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

Question 17

Give 2 gram positive bacteria found in the gut, include their shape and O2 use

Answer 17

Clostridium perfringes- rod-shaped and anaerobic

Peptostreptococcus anaerobius: cocci and anaerobic

Question 18

Give 2 bacteria that are of the phylum: Firmicutes

Answer 18

Clostridia and Lactobacilli

Question 19

Give a bacteria that is of the phylum: Bacteroidetes

Answer 19

Bifidobacteria

Question 20

Give 2 examples of “beneficial bacteria”

What Is their action?

What is their overall effect on the body?

Answer 20

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

Question 21

Give 2 examples of “harmful bacteria”

What Is their action?

What is their overall effect on the body?

Answer 21

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

Question 22

Give 2 examples of “opportunistic bacteria”

What is an opportunistic bacteria and what is its effect on the body?

Answer 22

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

Question 23

Why are different bacteria found in different areas of the gut?

Answer 23

Because of the physical nature of the gut eg. pH and oxygen distribution

Question 24

What is special about the appendix?
What type of bacteria are usually found here?
What can happen if the appendix gets blocked?

Answer 24

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

Question 25

What are our “indigenous friendly bacteria”?

Give an example of 4

Answer 25

These are essential or beneficial flora (also known as a probiotic)

Bifidobacteria, Lactobacteria, Peptostreptococci, Enterococci

Question 26

What can be said about imbalances to our beneficial flora and development of disease?

Why is this the case?

Answer 26

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

Question 27

What is the definition of a Probiotic?

Answer 27

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

Question 28

List 3 benefits of probiotics in yogurt

Answer 28

1) introduces vitamins
2) increases satiety (fullness)
3) decreases weight gain

Question 29

Give 3 harmful effects of antibiotics (in particular broad spectrum) on gut flora

Answer 29

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

Question 30

What is the danger of Clostridium difficile + give its MoA

Answer 30

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

Question 31

Give 6 harmful agents that can damage microflora

Answer 31

antibiotics
poor diet 
bottle feeding 
alcohol
steroids
the OCP
stress
Infections
old age 
radiation

Question 32

List 4 common conditions though to be caused or effected by gut dysbiosis

Answer 32

1) UC
2) colon cancer
3) IBD,
4) Crohn’s
5) sepsis and multi-system organ failure

Question 33

How may gut dysbiosis lead to the formation of a tumour?

Answer 33

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

Question 34

How may chronic inflammation due to gut Dysbiosis effect the intestinal epithelium?

What can this progress to?

Answer 34

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

Question 35

Give 4 causes of chronic inflammation which can lead to a leaky gut

Answer 35

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)

Question 36

What could be a possible therapy against multi-drug resistance strains of bacteria?

What is this?

Answer 36

Using a bacteriophage: this is a virus that infects and replicates within bacteria, killing them

Question 37

Explain what the twin study involving mice showed about gut microflora

Answer 37

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

Question 38

What is stress?

What biological changes to the body occur during stress

Answer 38

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)

Question 39

What hormone is responsible for stress?

List the mechanism that triggers its release

Answer 39

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)

Question 40

What is Parkinson’s disease and what is its cause?

Which probiotic may be beneficial in treating this?

Answer 40

A degenerative condition causing tremor and motor impairment, caused by loss of dopamine-secreting neurons

Bacillus spp. produce dopamine

Question 41

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?

Answer 41

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)