Practice exam Flashcards
Mention the different hierarchical designations phylum, class, order, family, genus,
species and strain of the following bacteria: A. muciniphila Muc ATCC BAA-835T
Verrucomicrobia
Verrucomicrobiae
Verrucomicrobiales
Akkermansiaceae
Akkermansia
A. muciniphila
A. muciniphila Muc ATCC BAA-835T
What is the definition of probiotics?
Live microorganisms, adequate amounts, health benefits.
What is the definition of prebiotics?
Substrate, selectively utilized, host microorganisms, health benefits
Describe a clinical trial evaluating health benefits after consumption of a fermented
food product.
Mention and describe endpoints of the study, the study design, the
methods used and the results obtained. Use maximum 200 words.
During a lab in a course you isolated potential probiotic bacteria after culturing of a
saliva sample.
a) Describe in detail the culturing and isolation process as well as the
identification process including both method description (16S rRNA gene
sequencing) and data analysis using the specific software (BLAST).
The answer should include:
A description of the culturing on selective media (specify which and motivate your
choice), isolation of colonies, freezing of isolates, 16S PCR (describe universal
primers, amplification based on cycles at different temperatures, gel
electrophoresis), sequencing and BLAST.
On for example a saliva or fecal sample
b) Describe in detail the process for using qPCR for determination of the amount
of L. reuteri in your sample.
The answer should include:
A description DNA purification, using specific fluorescent primers for the qPCR
reaction, amplification based on cycles at different temperatures, how the light
signal is generated and how the results are received (by using the standard curve).
Describe in detail 3 different ways of how probiotics can affect the adaptive
immune system through bacterial epithelial cell interactions.
Suggestion of answer:
1. Presentation by dendritic cells can lead to modification of the activity signal in
T cells and changed production of cytokines.
2. Differentiation of B cells into plasma cells can lead to increased production of
IgA.
3. Through an activation signal the population of different subsets of T cells, e.g.
regulatory T-cells can be affected.
Describe in detail 3 different ways of how probiotics can affect the innate immune
system through bacterial epithelial cell interactions
Suggestion of answer:
1. By changing the microbiota, probiotic bacteria can modify the stimulation of
the pattern recognition receptors.
2. The cytokines produced by macrophages can be affected.
3. Up and down-regulation of membrane receptors can lead to a stronger or
weaker signal transduction.
T/F: All strains from the same species will act the same way
F
T/F: Dietary prebiotics must be degraded by the target host enzymes
F
T/F: Enterococcus occurs spontaneously in food
T
T/F: Restriction enzymes are important for qPCR-analysis
F
T/F: Effects of probiotic treatments are dose-specific
True
T/F: Homofermentative Lactobacillus produce lactic acid, acetic acid and butyric acid
F
T/F: Bifidobacterium ferments carbohydrates to acetic acid and lactic acid
True
T/F: An endpoint in clinical trials are all results from the analysis
F
T/F: Bacteriophages are viruses attacking bacteria
True
T/F: Synbiotics = Probiotics + Prebiotics
T
T/F: The predominating phyla of the mouth is Firmicutes
True
T/F: Microbiome is the microorganisms that live in an established environment
False
T/F: Dysbiosis and diversity is two different words describing the same status of the
microbiota composition
False
T/F: Next generation sequencing is only detecting viable cells
False
T/F: By the use of T-RFLP you will get an identification on species level
False
T/F: The predominating phyla of the vagina is Firmicutes e.g. Bifodobacterium spp.
False, lactobacillus not bifidobacterium. Lactobacillys is firmicutes though.
T/F: Probiotics can reduce diarrhea by counteracting C. difficile
True
T/F: Probiotics have been shown to reduce the incidence, duration and symptoms of
common cold by activation of T-lymphocytes
True
T/F: Next generation probiotics are generally regarded as safe
False
Describe four factors that influence the composition of our gut microbiota and give
examples of bacterial phyla, families, genus or diversity of bacteria that might be
affected by each factor
- Age: The microbiota is affected by low nutritional intake, antibiotic use,
changed physiology of the intestine and by changed immune functions and
is e.g. causing a decreased diversity and decreased levels of Bacteroides and
Bifidobacterium. - Early life exposure/colonization: Effects of delivery - Vaginal leads to a
microbiome composed of species similar to the mother’s vagina:
domination of Lactobacillus spp. and Prevotella spp.; Cesarean section
leads to a microbiome composed of predominant species similar to the skin
flora of the mother and hospital attendants: Proteobacteria and Firmicutes as
main phyla. - Diet (both early in life and later) has a significant effect on the microbiota
composition: For example effects of a vegetarian diet: the abundance of
Enterobacteriaceae is lower, greater richness, increased
Bacteroidetes:Firmicutes ratio. You can of course choose to describe the
effect of another diet as well. - Geographical location: Differences in geographical location will due to e.g.
different environment and different diets affect the microbiota composition.
One example of this is traditional rural diets that is often locally produced
and rich in fiber and plant polysaccharides but low in fat and animal protein:
Enrichment in Bacteroidetes and depletion in Firmicutes, abundance of bacteria from the genus Prevotella and Xylanibacter but lower numbers of
Enterobacteriaceae spp.
Define translocation in connection to the gastro-intestinal tract
Passage of viable cells, cell structures or other antigens through the
intestinal barrier due to increased permeability.
Mention 5 taxa that are included in the functional concept Lactic Acid Bacteria
(LAB).
Lactococcus, Lactobacillus, Leuconostoc, Oenococcus, Pediococcus,
Weisella.
