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BIOL 322: Diversity and Evolution of Microbial Life > 8.1. Bacterial Diversity in The Sulfur Cycle > Flashcards

8.1. Bacterial Diversity in The Sulfur Cycle Flashcards

1
Q

T/F

Sulfur metabolism gave rise to the earliest forms of life on earth

A

true

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2
Q

Microorganisms in the sulfur cycle can perform 2 types of metabolisms:

A
  1. assimilative metabolism
  2. dissimilative metabolism
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3
Q

Assimilative metabolism=

A

oxidation of sulfur compounds –> creates organic sulfur compounds for the organism to use

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4
Q

Dissimilative metabolism=

A

reduction of sulfur compounds –> get energy from sulfur compounds (respiration)

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5
Q

Why is there such huge diversity in the sulfur cycle?

A

Because of the chemistry of sulfur
- 8 oxidation states
- sulfur has forms that can be e- acceptors and forms that can be e- donors

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6
Q

List the 5 types of organisms (Bacteria and Archaea) that control the sulfur cycle

A
  1. purple sulfur bacteria
  2. green sulfur bacteria
  3. sulfate reducers
  4. sulfur reducers
  5. sulfur oxidizers
  • 1 and 2 are anoxygenic phototrophs, which we covered in lecture 7
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7
Q

What energy sources (2) do sulfate reducers use? Is this energy source an e- acceptor or donor?

A
  • H2
  • organic compounds

electron donor

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8
Q

Euryarchaeota are _____ _______ (reducers/ oxidizers)

A

sulfate reducers

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9
Q

Which bacteria are sulfate reducers?

A
  • proteobacteria (1 group)
  • firmicutes
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10
Q

Where do sulfur products sit on the “bad-good for energy” continuum?

A

mild-bad for energy (near the mid-top of the list)

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11
Q

What alternative metabolisms could sulfate reducers use?

A
  • Nitrate reduction
  • Fermentation
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12
Q

T/F

Sulfate reducers are obligatory anaerobes

A

true
(sulfate respiration)

ie they cannot use oxygen

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13
Q

Sulfate reducers use:
and produce:

A

use
H2 or organic compounds like lactate (they’re able to use hydrocarbons)

produce
H2S as a metabolic product of sulfate respiration

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14
Q

List 6 famous bacteria sulfate reducers

A
  • desulfomonas
  • desulfotomaculum
  • desulfobacter
  • desulfovibro
  • thermodesulfobacterium
  • thermodesulfovibrio
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15
Q

List 1 famous sulfate reducer from Archaea

A

archaeoglobus

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16
Q

Describe the sulfate reducer “desulfotomaculum”.
- Where does it live? How do we use it?

A
  • Lives in soils
  • Found in canned foods= responsible for the smell
  • Forms endospores (dormant alternate life forms)
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17
Q

What do the following organisms all have in common?
- thermodesulfobacterium
- thermodesulfovibrio
- archaeoglobus

A
  • sulfate reducers
  • thermophilic
  • found in geothermally heated enviros like hot springs
18
Q

Describe the ecology of sulfate reducers:
- Found in _____ (oxic/ anoxic) areas
- abundant in marine ____
- responsible for the ______ ____ smell in marine areas

A
  • anoxic
  • sediments
  • rotten egg
19
Q

T/F
Desulfovibrio are one of the few sulfate-reducing bacteria that are not present in the human gut

A

False

Desulfovibrio are present in the human gut –> they produce H2S, which reacts with Fe2+ in the gut to form a black precipitate and spread colonies

20
Q

What energy source do sulfur reducers use?

A

H2 and organic compounds
- eg. acetate, succniate, formate, ethanol, propanol

21
Q

Which bacteria/ archaea are sulfur reducers?

A

Bacteria: 3 groups of proteobacteria
Archaea: Chrenarchaeota

22
Q

T/F
Sulfur reducers are obligatory aerobes

A

false

they’re obligatory ANAEROBES (sulfur respiration)

23
Q

Sulfur reducers can be ____ _____ as an alternative metabolism

A

facultative aerobics

24
Q

List 5 famous sulfur reducers
(2 Bacteria, 3 Archaea)

A

Bacteria:
- desulfomonas
- sulfospirillim

Archaea:
- thermoproteales
- sulfolobales
- mathanogens

25
Q

Would it make sense to find sulfur reducers in close proximity to sulfate reducers?

A

Yes because they use similar compounds to generate energy

26
Q

Sulfur reducers use __ to create ___, which is then used by anoxygenic phototrophs

A

S
H2S

27
Q

Sulfur oxidizers use ____ as an energy source (e- ____)

A

H2S and S
donor

28
Q

Which bacteria and archaea are sulfur oxidizers?

A

Bacteria: 3 groups of proteobacteria
Archaea: crenarchaeota

29
Q

Give 2 alternative metabolisms that sulfur oxidizers can use

A
  • organic compounds as energy source
  • deposit of sulfur granules that can be used if H2S is exhausted
30
Q

Sulfur oxidizers are chemolithotrophs, meaning:

A

they use inorganic compounds to extract energy

31
Q

List 4 famous sulfur oxidizers (2 bacteria, 2 archaea)

A

Bacteria:
- thiobacillus
- acidithiobacillus ferrooxidans

Archaea:
- sulfolobus
- metallosphaera sedula

32
Q

Acidithiobacillus ferrooxidans uses ___ as its electron donor

A

FES2

33
Q

thiobacillus uses ___ or ___ and produces ___ ____.

This is the best studied one!

A

H2S or S

sulfuric acid

34
Q

How is Acidithiobacillus ferrooxidans beneficial for mining?

A

Acidithiobacillus ferrooxidans oxidizes FES2: releases iron from sulfur.
= iron is extracted from ores, which helps us

35
Q

Bioleaching=

A

metal extraction from ores via microorganisms
- beneficial for mining
- used for lots of different metals
- example for iron: Acidithiobacillus ferrooxidans (sulfur oxidizer)

36
Q

How is Acidithiobacillus ferrooxidans harmful for mining?

A

Bioleaching releases iron from sulfur, but also other metals are released.
Can cause acidification, and release of toxic metals

37
Q

Many sulfur oxidizers evolved to use ___ as a donor and ___ as an acceptor. Why is this surprising?

A

H2S
O2

Because H2S and O2 are VERY reactive together. This is possible due to ecological strategies they developed

38
Q

There are 3 possible explanations for how sulfur oxidizers evolved to use H2S and O2. What are they?

A
  1. O2 dependent positioning (in Bacteria Beggiatoa)
  2. Anaerobic vacuole
  3. Symbiotic Association
39
Q

Explain how O2 dependent positioning could explain how sulfur oxidizers evolved to use H2S and O2.

A
  • cyanobacteria produce O2 in photosynthesis (daytime) on top of microbial mats
    -Beggaitoa on the bottom in daytime, and goes to top during nightime to get O2.

= H2S oxidized and O2 reduced to produce energy

40
Q

Explain how anaerobic vacuoles could explain how sulfur oxidizers evolved to use H2S and O2.

A

Thiomargarita

Bacteria uses H2S and NO3- (nitrite respiration)
Process occurs in vacuole

  • storage of sulfur and ammonium: bacteria used S and O2 instead of H2S and O2
41
Q

Explain how symbiotic association could explain how sulfur oxidizers evolved to use H2S and O2.

A

Yeti crab= eukaryotic host

  • host regulates levels of H2S and O2 (balancing)
  • bacterium fixes CO2 for the host
42
Q
A

BIOL 322: Diversity and Evolution of Microbial Life (11 decks)

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