Adaptation
•! What environmental factors affect growth?
•! Cell structure and growth
•! Adaptations to environmental factors •! Cold adaptation in SRB •! Growth above 100 ˚C
What environmental factors affect growth?
•! Temperature
•! pH •! Water availability •! Oxygen
•! Pressure •! Light and radiation •! (Energy & carbon source)
Extreme <-> Normal
Specialist <-> Generalist
Growth <-> Survival
Permanent <-> Transient
Obligate <-> Tolerant
Growth
Transport
Biosynthesis Maintenance of highly organized structure Regulation
Reproduction Detoxification
What environmental factors affect growth?
•! Temperature
•! pH •! Water availability •! Oxygen
•! Pressure
Temperature limits for life
•! Freezing point in seawater around -2 ˚C
•! Partially liquid in antarctic sea ice at -15 ˚C •! Liquid up to 300 ˚C at high pressure •! Only Prokaryotes grow above 65 ˚C
•! Upper limit: strain 121 grows at 121 ˚C
What environmental factors affect growth?
•! Temperature
•! pH •! Water availability •! Oxygen
•! Pressure
pH and microbial growth
•! pH range for growth limited to 2 units
•! How can they generate proton motive force? •! Picrophilus oshimae (pH 0.7 - 2)
•! Sea water in general well buffered around pH 8
What environmental factors affect growth?
•! Temperature
•! pH •! Water availability •! Oxygen
•! Energy & carbon source
Water activity, osmosis, and halophiles
•! All organisms require water •! Water content and substances dissolved in water •! Sea water contains about 3% NaCl •! Halophiles: salt-loving organisms
Water activity, osmosis, and halophiles
•! All organisms require water •! Water content and substances dissolved in water •! Sea water contains about 3% NaCl •! Halophiles •! Osmophiles: live in environments high in sugars •! Xerophiles: live in very dry environemnts
Compatible solutes allow growth under conditions of low water activity.
Quelle: Brock Biology of Microorganisms
Compatible solutes increase the internal solute concentration.
Quelle: Brock Biology of Microorganisms
What environmental factors affect growth?
•! Temperature
•! pH •! Water availability •! Oxygen
•! Pressure
What environmental factors affect growth?
•! Temperature
•! pH •! Water availability •! Oxygen
•! Pressure
Does pressure affect microbial growth?
Pressure increase by 1 bar per 10 m water depth
How can they stand 100 bar in 1000m depth?
Bert Engelen
Temperature adaptation in SRB
Dissimilatory sulfate-reduction occurs between -1.8 ˚C (arctic sediment) and above 100 ˚C (Guaymas basin sediment)
High phylogenetic and physiological diversity
permantly < 5°C
SO42- H2S
SO42- H2S
SO42- H2S
SO42- SO4
2-
changing temperatures
Tropical and
moderate climate
Polar regions
More than 90 % of the ocean biosphere is permantly cold!
Cold adaptations of microorganisms
•! Effects on growth rate and growth yield
•! Metabolic activity •! Protein flexibility and cold-adapted
enzymes
•! Protein synthesis and cold-induced proteins •! Effects on membrane and lipid structure
Isfjorden (Station D)
Kongsfjorden (Station F)
Bremen
Smeerenburgfjorden (Station J)
Krossfjorden (Station G)
Ny Ålesund
Longyearbyen D
G
J
Spitzbergen
0 °C
10 °C 20 °C 30 °C 40 °C
Ice
Mesophilic Most isolated SRB (since Beijerink, 1895)
Psychrotolerant: e.g. Desulfobacter hydrogenophilus (Widdel, 1987)
Psychrophilic Isolates from Arctic sediments (Knoblauch et al., 1999)
Temperature range
Optimal temperature
saturated fatty acids
cis-unsaturated fatty acids
short-chain fatty acids
branched fatty acids
Low temperature High temperature
Temperature adaptation of bacterial membrane fatty acids
saturated fatty acids
long chain fatty acids
Desaturase De novo- synthesis
De novo- synthesis
De novo- synthesis
4 °C 12 °C 20 °C 28 °C
Desulfofaba gelida
Desulfofrigus oceanense
Desulfotalea psychrophila
Desulfotalea arctica
40%
73%
82%
85%
70%
78%
83%
contains high amounts(>70%) of short chain fatty acids
Effect of temperature on unsaturated fatty acids in psychrophilic SRB
Desulforhopalus vacuolatus
85% 81%
Total amount of unsaturated fatty acids
Desulfovibrio desulfuricans
Desulfococcus multivorans
Desulfosarcina variabilis
49%
25%
23%
23%
22%
Desulfobacter hydrogenophilus
65% 27% 43% 61%
50%
Desulfobacter postgatei
43% 11% 24%
4 °C 12 °C 20 °C 28 °C
Effect of temperature on unsaturated fatty acids in mesophilic SRB
Total amount of unsaturated fatty acids
0
10
20
30
40
50
0 5 10 15
cyc 17:0
c9 16:1
10Me 16:0
16:0
0,00
0,10
0,20
0,30
0,40
0 5 10 15
Time (days)
0,4
0,3
0,2
0,1
OD
660 n
m"
Fatty a
cid
conte
nt (%
)"
0"
0,1"
0,2"
0,3"
0,4"
0" 10" 20" 30" 40" 50
Time (days)
OD
66
0 n
m"
0"
10"
20"
30"
40"
50"
0 200 400 600 800 1000
Fatty a
cid
conte
nt (%
)"
16:0
c9 16:1
10Me 16:0
cyc 17:0
12 °C 28 °C Precultured at 28 °C
Time course of changes in cellualr fatty acids at different growth-temperatures in D. hydrogenophilus
Changes in the fatty acid composition of Desulfobacter hydrogenophilus
Saturated Fatty acids
16:0
Cyclopropane Fatty acids
cyc17:0
cis-unsaturated Fatty acids
c9 16:1
De novo synthesis
CFA-Synthase
Low Temperature High Temperature
(Stationary growth-phase)
•! exhibited constant fatty acid composition with high amounts of unsaturated or short-chain fatty acids.
•! are “specialists“ in a small temperature range, in which they probably outcomplete mesophilic/ psychrotolerant species.
•! change the ratio of saturated, unsaturated and cyclopropane containg fatty acids with changing temperature via de novo synthesis.
•! are “generalists“, which propably outcomplete psychrophiles in environments with changing tempeartures.
Psychrophiles (permantly cold sediments)
Psychrotolerants (moderate climate)
Black Smoker (hydrothermal vent)
C. Cary
So-called "black smokers" are the hottest of the vents. They spew mostly iron and sulfide, which combine to form iron monosulfide. This compound gives the smoker its black color.
Etherlipids in Archaea
Side chains consist of repeating isoprene units!
Quelle: Brock Biology of Microorganisms
Structure of archaeal membranes
Glycerol-diether Glycerol-tetraether
Quelle: Brock Biology of Microorganisms