Marine Microbiology

Question 1

Describe some of the main characteristics of prokaryotes.

Answer 1

• Include bacteria and archaea
• Occur in large numbers
• Relatively small cells with small genome
• Large diversity
• Most phyla poorly understood.

Question 2

What are the three main methodologies to obtain microbial genomes?

Answer 2

• Single-cell genomics
• Culture
• Metagenomics.

Question 3

What are polyextremophiles and give an example.

Answer 3

Adapted to live in habitats where various physicochemical parameters reach extreme values e.g. microbes.

Question 4

Name the different types of polyextremophiles.

Answer 4

• Hyperthermophiles (temperatures)
• Acidophiles (pH)
• Halophiles (salinity)
• Piezophile/barophile (pressure).

Question 5

Define oligotrophy.

Answer 5

Growth at low nutrient concentrations.

Question 6

Why are marine microbes so small?

Answer 6

Small cell size is a way to cope with low substrate
availability. It increases the surface area to volume ratio – very important in marine systems!• Substrate uptake is via cell
membrane proteins. Increasing
SA/Vol improves the ability to
supply nutrients to the
cytoplasmic volume.

Question 7

What controls and limits the population size of marine microbes?

Answer 7

Nutrient availability.

Question 8

Describe the growth rate of marine microbes and why they are that way.

Answer 8

Low growth rate as nutrients are removed rapidly.

Question 9

How do different microbes get their energy?

Answer 9

• Phototrophs (photosynthetic, energy from sunlight)

- Chemotrophs (energy from oxidation of chemicals).

Question 10

What are the different types of chemotrophs?

Answer 10

• Chemo-litho-trophs - energy from oxidation of inorganic chemicals
• Chemo-organo-trophs - energy from oxidation of organic chemicals.

Question 11

How do microbes obtain their carbon?

Answer 11

• Autotrophic - An organism that can make organic molecules from inorganic nutrients
• Heterotrophic - An organism that cannot make organic molecules from inorganic nutrients. Depends on organic matter for energy generation and precursors for cell material.

Question 12

Give an example of a photoautotroph.

Answer 12

Cyanobacteria.

Question 13

Give an example of a chemoautotroph.

Answer 13

Thaumarchaeota.

Question 14

Give an example of a photoheterotroph.

Answer 14

Halobacteria.

Question 15

Give an example of a chemoheterotroph.

Answer 15

Proteobacteria.

Question 16

What are the typical characteristics of the marine environment?

Answer 16

• pH 8.1
• High salt concentrations
• Often low nitrogen and phosphorous concentrations
• Often low oxygen concentrations
• Often low concentrations of organic carbon.

Question 17

What are phytoplankton?

Answer 17

Oxygenic photoautotrophs in photic (surface) water.

Question 18

Name the most abundant primary producers in the oceans.

Answer 18

• Cyanobacteria
• Diatoms
• Dinoflagellates.

Question 19

What is marine snow and why is it important?

Answer 19

• Detritus which has aggregated into larger particles

- the major transport of primary production energy into deeper oceanic layers.

Question 20

What is detritus made of and how?

Answer 20

Mucopolysaccharides or extra polymeric substances (EPS) are produced by
bacteria, algae, phytoplankton, zooplankton etc.

Question 21

At what depth is the deep sea zone?

Answer 21

> 1000m.

Question 22

How does nutrient status vary between inshore and open ocean?

Answer 22

• Higher nutrients inshore
• Due to higher productivity from more phototrophic organisms
• Bays and estuaries exposed to urban and agricultural pollution.

Question 23

From what does microbial metabolic diversity arise?

Answer 23

Ability to generate energy from different sources.

Question 24

What represents the largest portion of biomass and activity in the ocean?

Answer 24

Bacteria.