Block A Lecture 3 - Metabolic Diversity and Microbial Ecology

Question 1

What is metabolism?

Answer 1

The sum of all biosynthetic (anabolic) reactions in a cell

Question 2

What are 4 main anabolic materials?

Answer 2

Carbon, Nitrogen, Sodium and Potassium
(Slide 7)

Question 3

In addition to needing sufficient energy sources and anabolic raw materials, what else is needed for microbial growth?

Answer 3

“Trace elements”
E.g some elements, metal ions and vitamins used as enzyme co-factors, iron is important for growth
(Slide 7)

Question 4

What are 4 methods which microbes can use to get energy?

Answer 4

Chemolithotrophy (gain energy from the oxidisation of inorganic compounds)
Chemoorganotrophy (gain energy from the oxidisation of organic compounds)
Photoautotrophy (use carbon dioxide and light energy to undergo photosynthesis to make energy)
Photolithotrophy (use carbon dioxide and light energy but undergo anoxic photosynthesis using alternative electron donors)
(Slide 8)

Question 5

What does the -trophy ending mean?

Answer 5

“Feeding/nutrition”
(Slide 9)

Question 6

How do photoautotrophs generate energy?

Answer 6

They use light energy to drive the fixation of carbon dioxide resulting in the production of organic carbon compounds such as glucose
(Slide 9)

Question 7

What is chemotrophy?

Answer 7

Energy from the oxidation of chemicals
(Slide 9)

Question 8

What is an autotroph?

Answer 8

An organism which can make organic molecules from inorganic nutrients. It assimilates C-1 compounds (such as CO2 or CH4-)
(Slide 9)

Question 9

What is a heterotroph?

Answer 9

Uses performed organic molecules acquired from outside to generate energy and precursors for cell material. It cannot make organic molecules from inorganic nutrients
(Slide 9)

Question 10

What is oligotrophy?

Answer 10

It means “small feeding” and is growth at low nutrient concentrations
(Slide 10)

Question 11

Why is oligotrophy important?

Answer 11

As most of the biosphere has low available nutrients, or at least 1 limiting nutrient
(Slide 10)

Question 12

What is syntrophy?

Answer 12

It means “feeding together” and is when microbes exhibit interdependent metabolic fluxes ,microbes often do it, and it is also a form of mutualism and may or may not involve direct cell–cell contact
(Slide 11)

Question 13

What are the 2 types of syntrophy microbes can exhibit and what is the difference between the two?

Answer 13

Obligate and facultative
Obligate is when the syntrophy is necessary for the microbes survival and facultative is when it is a voluntary behaviour
(Slide 11)

Question 14

What 2 types of genes are required for microbes to use a specific C source?

Answer 14

Genes for transport and catabolism
(Slide 12)

Question 15

What are 4 possible final electron acceptors in the microbial electron transport chain?

Answer 15

Oxygen
Nitrate
Nitrite
Ferric iron
Sulphate
Sulphur
Carbon Dioxide
Fumarate
(Slide 16)

Question 16

What does the final electron acceptor in the microbial electron transport chain depend on?

Answer 16

The conditions and the organisms genetic repertoire
(Slide 16)

Question 17

What are 3 uses of microbial fermentation?

Answer 17

It can be used to make a variety of foods (like wine, beer, bread)

Industrial fermentation can be used to produce vitamins, amino acids and fine chemicals

Fermentation can be diagnostically useful in clinical microbiology
(Slide 17)

Question 18

What is secondary metabolism?

Answer 18

Metabolites not directly involved in growth, development or reproduction and are therefore not absolutely required for survival
(Slide 18)

Question 19

How do cyanobacteria create energy?

Answer 19

They are photoautotrophs
(Slide 20)

Question 20

How do chemoautotrophs make energy?

Answer 20

They fix carbon dioxide to make organic compounds. They obtain energy from (usually inorganic) chemicals
(Slide 21)

Question 21

What is nitrification?

Answer 21

The oxidation of ammonia (NH3) to nitrite (NO2-) and further to nitrate (NO3-)
(Slide 21)

Question 22

What do photoautotrophs grow using?

Answer 22

Light + Carbon Dioxide

Question 23

What do photoheterotrophs need to grow?

Answer 23

Light + Organic Carbon

Question 24

How do photoheterotrophs produce energy?

Answer 24

They use light energy to transfer protons across the membrane out of the cell, with the resulting proton gradient being used to generate ATP
(Slide 22)

Question 25

What is a halophile?

Answer 25

A microorganism that can thrive in high salt conditions
(Slide 22)

Question 26

How do chemoheterotrophs generate energy?

Answer 26

They use organic (carbon) compounds for both their carbon requirement and energy generation
(Slide 23)

Question 27

What nutrition type are most bacterial pathogens?

Answer 27

Chemoheterotrophs
(Slide 23)

Question 28

How do Bdellovibrio gain energy?

Answer 28

By predating other bacteria
(Slide 25)

Question 29

What has greater metabolic diversity; Archaea & Bacteria or Eukaryotes?

Answer 29

Archaea & Bacteria
(Slide 26)

Question 30

What is microbial ecology?

Answer 30

The basic distribution and ecology of microbes which is still not fully understood
(Slide 27)

Question 31

What is the Bass Becking hypothesis of microbial ecology?

Answer 31

“Everything is everywhere but the environment selects”
(Slide 27)

Question 32

What is the Van Niel hypothesis of microbial ecology?

Answer 32

Every molecule existing in nature can be used as a source of carbon or energy by a microorganism somewhere, and therefore suggests that microbes are found in every environment on earth
(Slide 27)

Question 33

What is niche construction?

Answer 33

How organisms help to shape the biochemical dimensions of their habitat
(Slide 28)

Question 34

What are 4 restrictions on where microbes can habitat?

Answer 34

-10 to 121 degree temperature range
0 to 11 pH range
0 to 6 M Nacl (salt) saturation range
Others: such as oxygen, pressure and radiation
(Slide 29)

Question 35

What does the “-phile” ending mean?

Answer 35

“Loving”
(Slide 30)

Question 36

What are 3 names for microbes that love extreme temperatures?

Answer 36

Psychrophiles (cold)
Thermophiles (hot)
Hyperthermophiles (very hot)
(Slide 30)

Question 37

What are microbes who love pH extremes called?

Answer 37

Acidophiles for acid loving microbes and alkaliphiles for basic loving microbes
(Slide 30)

Question 38

What are microbes who like high salt concentrations called (2 things)?

Answer 38

Halophiles and halotolerant microbes
(Slide 30)

Question 39

What are microbes who can survive in environments without much water called?

Answer 39

Xerophiles
(The -Xero prefix means dry)
(Slide 30)

Question 40

What can anaerobic microbes use to create energy in the absence of oxygen?

Answer 40

Alternative e-acceptors in the electron transport chain or fermentation
(Slide 31)

Question 41

What do aerobic microbes require defences against?

Answer 41

Reactive oxygen species (ROS)
(Slide 31)

Question 42

How can microbes adapt to grow at different temperatures?

Answer 42

Alterations in proteins and membranes
Specific adaptations such as synthesis of compatible solutes or antifreeze proteins
(Slide 32)

Question 43

What is an example of a bacterium which can survive high doses of radiation?

Answer 43

Deinococcus Radiodurans
(Slide 36)

Question 44

What is a diazotroph?

Answer 44

An organism which can fix nitrogen

Question 45

What are 2 elements and 1 trace element which all microorganisms require?

Answer 45

Sulphur, Phosphorous and Selenium

Question 46

What is something that loves to grow in high pressure conditions called?

Answer 46

A barophile