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Ali Microbiology > Environmental Influences > Flashcards

Environmental Influences Flashcards

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Biology 101 flashcards
1
Q

Environmental Limits on Microbial Growth

A
  1. Temperature 2. Pressure 3. Osmolarity 4. pH 5. Oxygen
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2
Q

Psychrophiles

A

Microbes that grow 15 degrees C or below (15 degrees C is the optimum growth temperature)

Proteins are more flexible and and require less energy (heat) to function

Contain anti-freeze proteins and cryoprotectants - allows them to grow in ice without freezing

When temperatures rise above 20 degrees C, their proteins denature and they grow poorly if at all

Can safely degrade toxic organic contaminants in the cold

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3
Q

Mesophiles

A

12 degreesC (15) - 45 degreesC

Optima range is between 20-40 degreesC

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4
Q

Thermophiles

A

40 degreesC (50) - 80 degreesC

Hyperthermofiles: fluorish up to 121 degrees C

Enzymes in these microbes dont unfold as easily as mesophilic enzymes, very stable with low amounts of glycine (an amino acid that contributes to an enzyme’s flexibility

Amino termini of proteins in these organisms often are tied down by hydrogen bonding to other parts of the protein, making them harder to denature

Contain special membranes

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5
Q

Extreme Thermophiles - Hyperthermaphile

A

65 degreesC - 121 degreesC

Book says growth above 80 degrees C

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6
Q

Psycrophilic vs. Psycrotolerant Organisms

A

Psychrotolerant organisms can grow at a faster rate, however they will both produce the same

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7
Q

Hottest Archaeon

A

Pyrolobus

Isolated from a black smoker vent

Strains grow at 113 degreesC and 121 degreesC

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8
Q

Bacterial Adaptations to life in the Heat

A

Enzymes - more stable folding structure

Membranes - more rigid structures

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9
Q

Thermus aquaticus

A

isolated from a hot spring by Thomas Brock –> heat stable polymerase for PCR

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10
Q

Adaptations to Life in the Heat (or pH extremes) - Bacteria

A
  • Cyclopropane
  • Saturated Lipids
  • Some branched chain fatty acids
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11
Q

Adaptations to Life in the Heat (or pH extremes) - Archaea

A
  • Cyclopentane
  • Branched lipids
  • Monolipid layer (tetraether)
  • Ether linkages
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12
Q

Heat Shock Response (when temperature is 5-10 degreesC above the optimum)

A

Emergency proteins produced:

  • Chaperone proteins keep proteins folded (called Heat Shock Proteins)
  • These are more resistant to heat

Induced by many stressful conditions:

  • Heat
  • High salt concentrations
  • Arid conditions
  • pH
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13
Q

Mariana Trench - 2006

A

First time glowing lava has ever been witnessed from a submarine volcanic eruption

Discovery of the Sulfur Cauldron - bubbling sulfur

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14
Q

A microbe adapted to ocean life is a:

A

Mild halophile

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15
Q

Salt loving: halophiles

A
  • Mild halophile: 1-6% NaCl
  • Moderate halophile: 7-15% NaCl
  • Extreme halophile: 15-30% NaCl

NOTE: oceans are about 3% salt

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16
Q

Halobacterium halobium (an archaean)

A

“purple membrane”, formed by patches of light-harvesting pigment (proton pump)

bacteriorhodopsin forms ATP from light

heterotrophic

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17
Q

Bacteriorhodopsin

A

protein that sits inside the membrane and helps build proton motif force

Found inside Halobacterium halobium

Retinal is found inside

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18
Q

Effects of Osmolarity on Microbial Growth

A

Outside solute concentration higher than inside (hypertonic)

High osmolarity reduces available water (decrease Aw)

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19
Q

How do cells combat being hypertonic?

A

Release water through aquaporins

Compatible solutes (K+, glutamic acid, proline)

20
Q

Hypotonic

A

Low osmotic pressure outside cell

21
Q

How do cells combat being hypotonic?

A

Mechanosensitive channels relieve stress

Release cell contents

Influx of water through aquaporins

22
Q

Aquaporins

A

Located in cytoplasmic membrane

Found in all 3 domains (Archaea, Bacteria, Eukarya)

Non-essential for survival

Lab strain of S. cerevisiae contain inactivating mutations in the aquaporins genes

Small channels to let water in/out

23
Q

Neutralophiles

A

Grow at pH 5-8

Include bacteria in gut

24
Q

Acidiphiles

A

Grow at pH 0-5

Some grow in stomach acid

Some in sulfuric acid springs

Acidic peat bogs

25
Q

Sulfolobus acidocaldarius

A

Acrchaeon that lives in hot acidic waters in Yellowstone

26
Q

Alkaliphiles

A

Grow at pH 9-11

Found in soda lakes (often saline as well)

27
Q

Picrophilus oshimae

A

an acidiphilic archeon that lives in soils associated with volcanic activity

pH optimum is .7; lyses at pH 4

Grows at the lowest pH (record holder acidiphile)

28
Q

Ferroplasma acidarmanus strain fer1

A

Acid mine drainage

Growth range: pH - (min for life) up to 2.5

Optimum at pH 1.2

29
Q

Growth at high pH example

A

Soda Lakes: Lake Magadi in Kenya (with pink Spirulina, the reason pink flamingos are pink)

The great salt lake

30
Q

Alkaliphiles

A

Reduced number of basic amino acids exposed to cytoplasm in alkaliphilic enzymes (acidophiles?)

Teichuronic acid and teichuronopeptide production in alkaliphilic cell walls

31
Q

Acidophiles

A

Reduced number of acidic amino acids exposed to cytoplasm

Change proteins and folding structure

32
Q

Adaptations

A

Active efflux of undesirable molecules (acids, bases, protons, etc.)

Import of desired molecules

IMPORTANT: cytoplasmic pH is maintained closer to neutral (6-8), regardless of outside pH

33
Q

pH homeostasis in E. coli

A

Amino-acid decaroxylases remove protons under low pH

Potassium/proton antiporters work under mild acidity

Sodium/proton antiporters scavenge protons in an alkaline environment

34
Q

Na+ Circulation in Alkaliphiles

A

Sodium motif force used to power ATPase

35
Q

Oxygen

A

Most archaea and bacteria can survive w/o oxygen

Atmosphere: now 20% O2, primordial earth anaerobic (w/o O2) for about 1 billion years

Many eukaryotes and some bacteria need oxygen to survive (exception some fungi and protozoa)

IMPT: O2 is the ultimater electron acceptor

36
Q

Aerobes

A

used O2 as an electron acceptor

37
Q

Anaerobes

A

sensitive to O2 (ROS, H202, O2-)

38
Q

Facultative

A

can grow with or without O2

like a certain amount of O2

39
Q

Microaerophiles

A

Prefer low levels of O2

40
Q

Other Electron Acceptors

A

Anaerobes pass electrons to different ultimate electron acceptors

  • Anaerobic respiration: inroganic electron acceptors such as Nitrate, Nitrite, Thiosulfate
  • Fermentation: organic electron acceptors

Thrive in anaerobic environments: early earth, deep water, lower gut

41
Q

Toxicity of Oxygen

A

Toxic intermediates: result of metabolic reactions involving oxygen

Hydroxyl radicals cannot be detoxified enzymatically

They can damage carbohydrates, nucleic acids, lipids, and amino acids

Ex: catalase used to convert peroxide to H20 + O2

42
Q

Detoxifying Enzymes

A
43
Q

•You isolate two new organisms from a mine shaft in Virginia. One was cultured at low pH from acid mine drainage and one (from the mine walls) grows at pH 7. Lipid characterization results arrive. Which organism is this:

A.Acid mine drainage microbe

B.Mine walls

A

A. Acid Mine Drainage Microbe

44
Q

Arrhenius Equation and growth rate

A

growth rate roughly doubles for every 10 degrees C rise in temperaure

However, at upper and lower limits this breaks down

45
Q

Psychrotolerant bacteria

A

Cold-resistant mesophiles that grow between 0-35 degrees C

Can cause milk to spoil in the refrigerator

46
Q

Heat Shock Response

A

Produces a series of protective organisms exposed to temperatures near the upper edge of their growth range

Ali Microbiology (8 decks)

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