Block A Workshop - Microbial Ecology

Question 1

What is species richness?

Answer 1

The measurement of how many species there are
(Slide 5)

Question 2

What is species evenness?

Answer 2

The measurement of how abundant the species present are
(Slide 5)

Question 3

What are the 2 different classes of methods we can use to measure species richness and evenness?

Answer 3

Culture-independent methods (such as 16S rRNAs, OTUs and metagenomics) and culture-dependent methods
(Slide 5)

Question 4

What do microbiomes play key roles in?

Answer 4

Host physiology, development, immune function/defense and nutrition
(Slide 6)

Question 5

What can be used to measure diversity?

Answer 5

Shannon index (H)
(Slide 17)

Question 6

What does a higher Shannon index (H) mean?

Answer 6

A more diverse community with 0 meaning there is only 1 species
(Slide 17)

Question 7

What does colony-forming units (cfu) refer to?

Answer 7

The number of cells present in the original sample
(Slide 20)

Question 8

How is cfu/ml calculated?

Answer 8

First need to serially dilute
cfu/ml = number of colonies counted / dilution factor x volume plated
(Slide 21)

Question 9

What are Winogradsky columns?

Answer 9

A column which acts as an artificial microbial ecosystem. They can act as enrichment culture (for different microbes depending on the substrate(s) added)
(Slide 23)

Question 10

What forms in Winogradsky columns?

Answer 10

Gradients of oxygen and other nutrients
(Slide 23)

Question 11

What does oxygen and other nutrient gradients forming in Winogradsky columns lead to?

Answer 11

Microbes growing in different zones according to their physiology
(Slide 23)

Question 12

What do purple/green non-sulphur bacteria usually carry out and what can they possibly have the ability to fix?

Answer 12

They usually carry out anoxygenic photosynthesis, and may be able to fix nitrogen
(Slide 24)

Question 13

What is anoxygenic photosynthesis?

Answer 13

Photosynthesis in which oxygen is non produced as a by-product
(Slide 24)

Question 14

What type of photosynthesis do purple sulphur bacteria use?

Answer 14

Photosynthesis using sulphide or thiosulfate as an electron donator
(Slide 24)

Question 15

What are green sulphur bacteria?

Answer 15

Obligate anaerobes which undergo anoxygenic photosynthesis using hydrogen, hydrogen sulphide (H2S) or sulphur as electron donors
(Slide 24)

Question 16

What are sulphate reducing bacteria?

Answer 16

Obligate anaerobes which produce sulphide
(Slide 24)