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Adaptation to specific environmental conditions

Martin Könneke www.icbm.de

Adaptation

• What environmental factors affect growth?

• Cell structure and growth

• Adaptations to environmental factors

• Cold adaptation in SRB

• Growth above 100 ˚C

(2)

What environmental factors affect growth?

• Temperature

• pH

• Water availability

• Oxygen

• Pressure

• (Energy & carbon source)

Extreme <-> Normal Specialist <-> Generalist

Growth <-> Survival Permanent <-> Transient

Obligate <-> Tolerant

(3)

Growth Transport

Biosynthesis

Maintainance of highly organized structure Regulation

Detoxification

Macromolecules in the cell

Quelle: Brock Biology of Microorganisms

(4)

Fluid-mosaic structure of the membrane

Quelle: Brock Biology of Microorganisms

What environmental factors affect growth?

• Temperature

• pH

• Water availability

• Oxygen

• Pressure

(5)

Quelle: Brock Biology of Microorganisms

(6)

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

The acido- and thermophilic algae Cyanidium caldarium

Yellowstone NP, (~50 ˚C, pH 2)

(7)

What environmental factors affect growth?

• Temperature

• pH

• Water availability

• Oxygen

• Pressure

Quelle: Brock Biology of Microorganisms

(8)

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

(9)

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

Quelle: Brock Biology of Microorganisms

NaCl

(10)

Quelle: Brock Biology of Microorganisms

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

(11)

Compatible solutesallow growth under conditions of low water activity.

Quelle: Brock Biology of Microorganisms

Compatible solutesincrease the internal solute concentration.

Quelle: Brock Biology of Microorganisms

(12)

What environmental factors affect growth?

• Temperature

• pH

• Water availability

• Oxygen

• Pressure

Toxic forms of oxygen

(By-products during O

2

reduction)

(13)

Quelle: Brock Biology of Microorganisms

(14)

What environmental factors affect growth?

• Temperature

• pH

• Water availability

• Oxygen

• Pressure

(15)

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

(16)

permantly < 5°C

SO42-H2S SO42-

H2S

SO42-H2S

SO42- SO42- changing temperatures

Tropical moderate and

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

(17)

0 °C 10 °C 20 °C 30 °C 40 °C

Ice

MesophilicMost isolated SRB (since Beijerink, 1895)

Psychrotolerant: e.g. Desulfobacter hydrogenophilus(Widdel, 1987)

PsychrophilicIsolates from Arctic sediments (Knoblauch et al., 1999)

Temperature range Optimal temperature

(18)

Fluid-mosaic structure of the membrane

Quelle: Brock Biology of Microorganisms

saturated fatty acids cis-unsaturated

fatty acids

short-chain branched fatty acids

Low temperature High temperature

Temperature adaptation of bacterial membrane fatty acids

saturated fatty acids

long chain

Desaturase De novo- synthesis

De novo- synthesis

De novo-

(19)

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% 61% 43% 27%

50%

Desulfobacter

postgatei 43% 24% 11%

4 °C 12 °C 20 °C 28 °C

Effect of temperature on unsaturated fatty acids in mesophilic SRB

Total amount of unsaturated fatty acids

(20)

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 nmFatty acid content (%)

0 0,1 0,2 0,3 0,4

0 10 20 30 40 50

Time (days)

OD 660 nm

0 10 20 30 40 50

0 200 400 600 800 1000

Fatty acid content (%)

16:0 c9 16:1

10Me 16:0 cyc 17:0

12 °C Precultured at 28 °C 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

SynthaseCFA-

Low Temperature High Temperature

(Stationary growth-phase)

(21)

Protein pattern of

Desulfobacterium autotrophicum Grown at different temperatures

• 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)

(22)

Quelle: Brock Biology of Microorganisms

Black Smoker (hydrothermal vent)

C. Cary

So-called "black smokers" are the hottest of the vents.

(23)

Quelle: Brock Biology of Microorganisms

Lipid bonds in Bacteria, Eukarya and Archaea

Quelle: Brock Biology of Microorganisms

(24)

Etherlipids in Archaea

Side chains consist of repeating isoprene units!

Quelle: Brock Biology of Microorganisms

Structure of archaeal membranes

Glycerol-diether Glycerol-tetraether

(25)

In general,temperature is the most

important environmental factor in marine systems.

…and easy to reproduce in the lab!

Referenzen

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