Download Brock Biology of Microorganisms, Twelfth Edition

752-4001-00L Mikrobiologie
Julia Vorholt
Lecture 9:
Phototrophy and autotrophy
Global carbon and nitrogen cycles
Nov 19, 2012
Brock Biology of Microorganisms, Twelfth Edition
– Madigan / Martinko / Dunlap / Clark
Copyright © 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
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Nutrients and microbial growth
Introduction to principles of metabolism
Chemoorganotrophy
Chemolithotrophy
Phototrophy
Autotrophy, nitrogen fixation
Global carbon, nitrogen, sulfur cycles
Brock Biology of Microorganisms, Twelfth Edition
– Madigan / Martinko / Dunlap / Clark
Copyright © 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Photophosphorylation and ETP
ELQ = h c NA -1 = h v
ELQ, Free energy of light quanta
h, Planck constant (6.6 x 10-34 J s)
c, the speed of light (3 x 108 m s-1)
NA, Avogadro‘s number (6 x 1023)
v, frequency
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Types of Photosynthesis
Phototrophs
Purple and green bacteria
Cyanobacteria, algae, green plants
Oxygenic
Anoxygenic
Reducing power
Carbon
electrons
Energy
Reducing power
Carbon
Light
Energy
Light
PS I and II
PS I or II
Van Niel, 1930: Photosynthesis
CO2 + 2 H2A -> [CH2O] + 2 A + H2O
Copyright
Chap.
13.1© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 13.2
Groups of Phototrophs
Green
Sulfurbacteria
Green
Nonsulfurbacteria
Cyanobacteria
Heliobacteria
(Gram +)
Purple bacteria (Proteobacteria)

Purple Nonsulfur Bacteria


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Purple Sulfur Bacteria
Evolutionary Aspects
Eon
BYA Organisms,
events
0
Sunlight represents the most
important energy source on earth.
Phototrophs use light as sole
energy source.
They are the starting point of the
food chain.
The oxygenic photosynthesis
evolved rather early in evolution,
2.7 billion years ago.
=> major consequences in terms of
primary biomass production
(unlimited availability of H2O) and
the presence of O2.
Phanaerozoic
O2
level
Extinction of the
dinosaurs
0.5
Early animals
1.0
Multicellular
eukaryotes
Metabolic
highlights
Cambrian
Precambrian
20%
10%
Proterozoic
1.5
2.0
First eukaryotes
with organelles
Ozone shield
1%
2.5
Great oxidation
event
0.1%
Endosymbiosis?
Aerobic respiration
Oxygenic photosynthesis
(2H2O  O2  4H)
Cyanobacteria
3.0
Archaean
Sulfate reduction
Fe3 reduction
3.5
Hadean
Purple and green
bacteria
Anoxygenic photosynthesis
Anoxic
Bacteria/Archaea
divergence
Acetogenesis
4.0
First cellular life; LUCA
Formation of
crust and oceans
Methanogenesis
4.5
Formation of Earth
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Sterile Earth
Fig. 16.6
Chlorophylls and Bacteriochlorophylls
 Organisms must produce some form of chlorophyll (or bacteriochlorophyll) to be
photosynthetic
 Chlorophyll is a porphyrin
 They are part of the reaction center (participate directly in the conversion of light
energy to ATP)
 Number of different types of chlorophyll exist with different absorption spectra
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13.2© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 13.3
Carotenoids and Phycobilins
 Phototrophic organisms have accessory pigments in
addition to chlorophyll, including carotenoids
 Carotenoids
 Always found in phototrophic organisms
 Typically yellow, red, brown, or green
 Energy absorbed by carotenoids can be transferred to a
reaction center
 Prevent photo-oxidative damage to cells
-carotene
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Chap.
13.3© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 13.8
Anoxygenic Photosynthesis
 Anoxygenic photosynthesis is
found in at least four phyla of
Bacteria
 Electron transport reactions
occur in the reaction center of
anoxygenic phototrophs
 Reducing power for CO2 fixation
comes from reductants present
in the environment (i.e., H2S,
Fe2+, or NO2-)
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Chap.
13.4© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 17.2
Fig. 17.6
Arrangement of Light-Harvesting Chlorophylls
RC, reaction center
LH, light harvesting molecules
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Chap.
13.2© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 13.6
Structure of Reaction Center in Purple Bacteria
Arrangement of Pigment Molecules
in Reaction Center
Molecular Model of the Protein Structure
of the Reaction Center
1988, Nobel prize for the structure of the reaction center of Rhodopseudomonas viridis:
J. Deisenhofer, H. Michel, and R. Huber
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Chap.
13.4© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 13.13
Electron Flow in Anoxygenic PS in a Purple Bacterium
1.0
Strong
electron
donor
0.75
0.5
E0
(V)0.25
Cyclic electron
flow (generates
proton motive
force)
0.0
External electron
donors (H2S, S2O32-,
S0, Fe2+)
0.25
Poor
electron
donor
0.5
Red or infrared light
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©
2009
Pearson
Education
Inc.,
publishing
as Pearson Benjamin Cummings
Chap. 13.4
Fig. 13.14
Arrangement of Protein Complexes in Reaction Center
Light
Out
(periplasm)
Quinone
pool
ATPase
Photosynthetic
membrane
In
(cytoplasm)
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Chap.
13.4© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 13.15
Electron Flow in Purple, Green, Sulfur and Heliobacteria
Purple bacteria
Green sulfur bacteria
Heliobacteria
1.25
1.0
0.75
0.5
E0 (V)
0.25
0
Reverse
electron
flow
0.25
0.5
Light
Light
Light
PSII
PSI
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Chap.
13.4© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
PSI
Fig. 13.17
Electron Flow in Oxygenic Photosynthesis
1.25
The Z Scheme:
1.0
PSII PSI
0.75
Cyclic electron
flow (generates
proton motive
force)
0.5
0.25
E0
0.0
(V)
0.25
Noncyclic
electron flow
(generates
proton motive
force)
Light
0.5
Photosystem I
0.75
1.0
Photosystem II
Light
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Chap.
13.5© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 13.18
Oxygenic Photosynthesis
 Oxygenic phototrophs use light to generate ATP and
NADPH
 The two light reactions are called photosystem I and
photosystem II
 “Z scheme” of photosynthesis
 Photosystem II transfers energy to photosystem I
 ATP can also be produced by cyclic
photophosphorylation
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Chap.
13.5© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Water blooms in lakes consisting of Cyanobacteria
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Autotrophic CO2-fixation
CO2 + 4 [H] + n ATP -> (CH2O) + H2O + n ADP + n Pi
6 different CO2 fixation pathways are known:
1.
2.
3.
4.
5.
6.
Calvin-Benson-Bassham cycle
Reductive citric acid cycle
Reductive acetyl-CoA pathway
3-Hydroxypropionate/malyl-CoA cycle
3-Hydroxypropionate/4-hydroxybutyrate cycle
Dicarboxylate/4-hydroxybutyrate cycle
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Chap.
13.12-13
The Calvin Cycle
12 3-PhosphoRubisCO
glycerate
(36 carbons)
6 Ribulose
1,5-bisphosphate
(30 carbons)
12 1,3-Bisphosphoglycerate
(36 carbons)
Phosphoribulokinase
 Fixes CO2 into cellular
material for autotrophic
growth
 Requires NADPH, ATP,
ribulose bisphophate
carboxylase (RubisCO),
and phosphoribulokinase
 6 molecules of CO2 are
required to generate one
molecule of glucose
12 Glyceraldehyde
3-phosphate
(36 carbons)
6 Ribulose
5-phosphate
(30 carbons)
Sugar
rearrangements
10 Glyceraldehyde
3-phosphate
(30 carbons)
Fructose
6-phosphate
(6 carbons)
To biosynthesis
Overall stoichiometry:
6 CO2  12 NADPH  18 ATP
 12 NADP  18 ADP  17 Pi
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Chap.
13.12
C6 H12 O6(PO3 H2)
Fig. 13.30
(Oxidized)
Nitrogenase and Nitrogen Fixation
(Reduced)
 Only certain prokaryotes can fix nitrogen
 Some nitrogen fixers are free living and others are symbiotic
Products
Nitrogenase
substrates
 Reaction is catalyzed by nitrogenase
 Sensitive to the presence of oxygen
 A wide variety of nitrogenases use different metal cofactors,
usually molybdenum
Overall reaction
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Chap.
13.14
Symbiotic Nitrogen Fixation
Soy bean
Root nodules
N2
NH3
with
Bradyrhizobium
(Alphaproteobacterium)
without
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Chap.
25.3© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
(Fig. 25.7)
Fig. 25.8
Symbiotic Nitrogen Fixation
 The mutalistic relationship between
leguminous plants and nitrogen-fixing
bacteria is one of the most important
symbioses known
 Examples of legumes include soybeans,
clover, alfalfa, beans, and peas
 Rhizobia are the most well-known
nitrogen-fixing bacteria engaging in
these symbioses
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Chap.
25.3© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Key terms Metabolism - I
We need to distinguish between energy sources and carbon sources
(both are usually identical for chemoorganotrophic organisms)
 Chemotrophy (energy from chemical substrates)
> Chemoorganotrophy (organic substrates)
> Chemolithotrophy (inorganic substrates)
Energy
sources
 Phototrophy (energy from light)
 Autotrophy (CO2 as main carbon source)
 Heterotrophy (organic compounds as main carbon source)
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Carbon
sources
Key terms Metabolism - II
 Aerobic: Growth of an organism using oxygen as electron acceptor
 Anaerobic: Growth of an organism not using oxygen as electron
acceptor
 Aerotolerant: Anaerobic organism whose growth is not inhibited by
oxygen and does not use it as electron acceptor
 Oxic: Environmental condition where oxygen is present
 Anoxic: Environmental condition without oxygen
 Oxygenic: Type of photosynthesis, oxygen is released from water
 Anoxygenic: Type of photosynthesis, without oxygen release
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The Carbon Cycle and Major Carbon Reservoirs on Earth
CO2
Human
activities
Respiration
Land
plants
Animals and
microorganisms
Aquatic
CO2
plants and
phytoplankton Biological pump
Fossil
fuels
Humus
Soil formation
Death and
mineralization
Earth’s crust
Aquatic
animals
CO2
Rock formation
Carbon is cycled through all of Earth’s major carbon reservoirs, i.e., atmosphere, land, oceans, sediments, rocks, and biomass
Copyright
Chap.
24.1© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 24.1
Methane hydrate
A methane hydrate is a cage-like
lattice of ice, inside of which are
trapped molecules of methane.
Copyright © 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Pictures by K. Kvenvolden and GEOMAR
The Carbon Cycle
(CH2O)n
Cyanobakterien
Pflanzen
Oxygene
Photosynthese
Tiere,
verschiedene
Mikroorganismen
(Paracoccus, E. coli)
Aerobe Atmung
(Chemolithotrophe)
Aerobe
Methanoxidation
CH4
CO2
Anaerobe
Methanoxidation
Oxisch
Anoxisch
Methanogenese
Anoxygene
Photosynthese
Anaerobe Atmung
Brock Biology
of Microorganisms, Twelfth Edition
Purpurbakterien
– Madigan / Martinko / Dunlap / Clark
(CH O)
2
n
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Chap.
24.1© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
E. coli
Paracoccus denitrificans
(Fig. 24.2)
Assimilation/Baustoffwechsel
Anaerober Prozess
Aerober Prozess
Brock Biology of Microorganisms, Twelfth Edition
– Madigan / Martinko / Dunlap / Clark
Copyright © 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Dissimilation/
Energiestoffwechsel
The Carbon Cycle
 Phototrophic organisms are the foundation of the carbon cycle
 CO2 is fixed primarily by photosynthetic land plants and marine
microbes
 CO2 is returned to the atmosphere by respiration of animals and
chemoorganotrophic microbes as well as anthropogenic activities
 Microbial decomposition is the largest source of CO2
released to the atmosphere
 The carbon and oxygen cycles are intimately linked
 Plants dominant phototrophic organisms of terrestrial
environments
 The two major end products of decomposition are CH4 and CO2
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The Nitrogen Carbon
Cycle
Rhizobien
Cyanobakterien
N2-Fixierung
Org. N
(NH2-Gruppen
N2
NH3
N2O
Ammonifikation
E. coli
Denitrifikation
Pseudomonas
Paracoccus
NO
Nitrifikation
Nitrosobakterien
(z.B. Nitrosomonas)
NO2Brock Biology of Microorganisms, Twelfth Edition
– Madigan / Martinko / Dunlap / Clark
Nitrobakterien
(z.B. Nitrobacter)
NO3-
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24.3© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
(Fig. 24.7)
The Nitrogen Cycle
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Chap.
24.3© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 24.7
The Nitrogen Cycle
 N2 is the most stable form of nitrogen and is a major reservoir
 The ability to use N2 as a cellular nitrogen source
(nitrogen fixation) is limited to only a few prokaryotes
 Denitrification is the reduction of nitrate to gaseous nitrogen
products and is the primary mechanism by which N2 is
produced biologically
 Ammonia produced by nitrogen fixation or ammonification can
be assimilated into organic matter or oxidized to nitrate
 Denitrification and anammox result in losses of nitrogen from
the biosphere
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Chap.
24.3© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
The Sulfur Cycle
Org. S
Chemolithotrophe
S-Oxidation
H 2S
Diss. S0
reduktion
Beggiatoa
Photolithotrophe
Dissimilatorische
Sulfatreduktion
Assimilatorische
Sulfatreduktion
Desulfovibrio
S0
SchwefelPurpurbakterien
SchwefelGrüne Bakterien
SO42Brock Biology of Microorganisms, Twelfth Edition
– Madigan / Martinko / Dunlap / Clark
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Chap.
24.4© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
(Fig. 24.8)
The Sulfur Cycle
 Hydrogen sulfide is a major volatile sulfur gas that is produced
by bacteria via sulfate reduction or emitted from geochemical
sources
 Sulfide is toxic to many plants and animals and reacts with
numerous metals
 Sulfur-oxidizing chemolithotrophs can oxidize sulfide and
elemental sulfur at oxic/anoxic interfaces
Copyright
Chap.
24.4© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Catabolic Diversity
Fermentation
Carbon flow
Organic compound
Carbon flow in
respirations
Electron transport/
generation of pmf
Biosynthesis
Aerobic respiration
Chemotrophs
Electron
acceptors
Anaerobic respiration
Chemoorganotrophy
Electron transport/
generation of pmf
Electron
acceptors
Biosynthesis
Aerobic respiration
Anaerobic respiration
Chemolithotrophy
Light
Phototrophs
Photoheterotrophy
Organic
compound
Photoautotrophy
Electron
transport
e
donor
Generation of pmf
and reducing power
Biosynthesis
Biosynthesis
Phototrophy
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Chap.
4.12© 2009 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 4.22
Chemoorganotrophy
Chemoorganotrophy
Energy and carbon
source:
organic compound(s)
Fermentation, anaerobic process without
external electron acceptors
Energy generating process:
Substrate-level-phosphorylation (SLP)
Example: Lactic acid fermentation
Catabolic end product: lactic acid (homofermentative)
Chemotrophs
Fermentation
Carbon flow in
respirations
Carbon flow
Organic compound
Electron transport/
generation of pmf
Biosynthesis
Aerobic respiration
Electron
acceptors
Anaerobic respiration
Chemoorganotrophy
Anaerobic respiration, alternative electron
acceptors (not O2)
Energy generating process:
Electron transport phosphorylation (and SLP)
Catabolic end product: CO2
(exception: methanogenesis -> CH4)
Example: Escherichia coli with nitrate
Aerobic respiration, O2 as electron acceptor
Energy generating process:
Electron transport phosphorylation (and SLP)
Catabolic end product: CO2
Example 1: Paracoccus
Example 2: Escherichia coli
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Chemolithotrophy
Energy source: reduced inorganic compound
Electron acceptor, mostly O2
Energy generating process: Electron transport phosphorylation
Catabolic end product: oxidized inorganic compound
Example: Nitrification of Nitro(so)bacteria
Carbon source: CO2 (in most bacteria/archaea)
Electron transport/
generation of pmf
Electron
acceptors
Biosynthesis
Aerobic respiration
Anaerobic respiration
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Phototrophy
Energy source: Light
Energy generating process: Electron transport phosphorylation
Carbon source: CO2 (in most bacteria)
Light
Photoheterotrophy
Organic
compound
Photoautotrophy
Electron
transport
e
donor
Generation of pmf
and reducing power
Biosynthesis
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Biosynthesis