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Chapter 5: Environmental Influences Flashcards

0
Q

Organisms growing outside normal growth conditions.

A

Extremophiles

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1
Q

What are “normal” growth conditions:

A
  1. Sea level (1 atm)
  2. Temperature 20-40 C
  3. Neutral pH
  4. 0.9% salt, and ample nutrients
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2
Q

The main criterion that a microbe’s environmental habitat is based on.

A

The tolerance of that organism’s proteins and macromolecular structures

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3
Q

Do bacteria regulate temp?

A

No. They match their immediate environment.

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4
Q

Each organism has an _______ temperature, as well as _______ and _______ temperatures that define its growth limits.

A

Optimum; minimum; maximum

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5
Q

Microbes that grow at higher temps typically achieve….

A

Higher rates of growth

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6
Q

The growth rate doubles for every…

A

10 degrees Celsius rise in temp.

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7
Q

The typical temp growth range usually spans an organism’s optimal growth temp by…

A

30-40 degrees

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8
Q

Live in 0-20 degrees

A

Psychrophiles

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9
Q

Live in 15-45 degrees

A

Mesophiles

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10
Q

Live in 40-80 degrees

A

Thermophiles

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11
Q

Live in 65-121 degrees

A

Hyperthermophiles

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12
Q

Heat-shock response is the result of…

A

Rapid temperature change during growth activities

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13
Q

What does the heat shock response activate and what do these produce?

A

Activates - stress response genes

Produces - chaperones and enzymes that change membrane lipid composition

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14
Q

What kind of organisms have the heat shock response?

A

All organisms do

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15
Q

Barophiles or piezophiles are adapted to…

A

Grow at very high pressures

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16
Q

_______ organisms grow well over the range of 1-50 MPa, but their growth falls off thereafter

A

Barotolerant

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17
Q

Many barophiles are also-

A

Psychrophiles

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18
Q

Water activity

A

A measure of how much water is available for use

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19
Q

Water activity is measured as…

A

The ratio of the soln’s vapor pressure relative to that of pure water

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20
Q

Most bacteria require water activity levels of

A

Greater than 0.91

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21
Q

Fungi can tolerate water activity levels of

A

Greater than 0.86

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22
Q

A measure of the number of solute molecules in a solution

A

Osmolarity

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23
Q

Osmolarity is ________ related to water activity

A

Inversely

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24
Q

Aquaporins

A

Membrane-channel proteins that allow water to traverse the membrane much faster than by diffusion

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25
Q

Aquaporins help protect from

A

Osmotic stress

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26
Q

Microbes’ 2 mechs to minimize osmotic stress:

A
  1. In hypertonic media they protect internal water by synthesizing or importing compatible solutes (eg proline or K+)
  2. In hypotonic media, pressure-sensitive or mechanosensitive channels can leak solutes out of the cell
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27
Q

Require high salt conc

A

Halophiles

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28
Q

Salt conc for halophiles

A

2-4 M NaCl

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29
Q

To achieve a low internal conc of Na+ halophilic microbes…

A

Use special ion pumps to excrete sodium and replace it with other cations, such as K+

30
Q

All enzyme activities exhibit______________ with regard to pH

A

Optima, minima, and maxima

31
Q

Do bacteria regulate internal pH?

32
Q

______ _______ pass through membranes and disrupt ____ homeostasis, thus killing cells

A

Weak acids; pH

33
Q

3 classes of organisms differentiated by the pH of their growth range:

A
  1. Neutralophiles
  2. Acidophiles
  3. Alkaliphiles
34
Q

______ _____ lakes have high salt conc and pH values as high as pH 11

A

Saline soda

35
Q

Saline soda lakes contain

A

Alkalophiles such as the archaeon Halobacterium salinarium and cyanobacterium Spirulina (flamingos)

36
Q

Most alkaliphiles use a ______ motive force in addition to a ______ motive force to do much of the work in the cell.

A

Sodium; proton

-also rely heavily on Na/H antiporters to bring protons into the cell

37
Q

When cells are placed in pH conditions below the optimum….

A

Protons can enter the cell and lower internal pH to lethal levels

38
Q

Microbes can prevent the unwanted influx of protons by..

A

exchanging extracellular K+ for intracellular H+ when the internal pH becomes too low

39
Q

Under extremely alkaline conditions, cells use…

A

Na/H antiporter to bring protons into the cell in exchange for Na

40
Q

Many microbes posses an emergency global response system called

A

Acid tolerance or acid resistance

41
Q

TEA

A

Terminal electron acceptor

42
Q

TEA in aerobic respiration

43
Q

Oxygen is toxic to cells that lack

A

enzymes capable of efficiently destroying the reactive oxygen species (ROC)

44
Q

Only grow in oxygen

A

Strict aerobes

45
Q

Grow in oxygen while retaining a fermentation-based metabolism

A

Aerotolerant anaerobes

46
Q

Facultative anaerobes

A

Can live with or without oxygen

47
Q

Grow only at lower O2 levels

A

Microaerophiles

48
Q

3 oxygen removing techniques

A
  1. Special reducing agents (thioglycolate) or enzyme systems (oxyrase) can be added to ordinary liquid media
  2. An anaerobe jar
  3. An anaerobic chamber with glove ports
49
Q

Starvation response

A

Enzymes are produced to increase the efficiency of nutrient gathering and tk protect cell macromolecules

Usually triggered by accumulation of small signal molecules like cAMP

50
Q

Eutrophication

A

the sudden infusion of large quantities of a formerly limiting nutrient

51
Q

Ways humans have caused nutrient pollution:

A
  1. Runoff from agricultural fields, urban lawns, and golf courses
  2. Untreated or partially treated domestic sewage
52
Q

Killing or removal of pathogens from inanimate objects

A

Disinfection

53
Q

Sterilization

A

Killing of all living organisms

54
Q

Killing or removal of pathogens from the surface of living tissues

A

Antisepsis

55
Q

Reducing the microbial population to “safe” levels

A

Sanitation

56
Q

Decimal reduction time

A

The length of time it takes an agent or a condition to kill 90% of the population

57
Q

Steam autoclave

A

121 C at 15 psi for 20 minutes

58
Q

LTLT

A

Low temp/ long time pasteurization (63 C for 30 min)

59
Q

HTST

A

High temp/ short time pasteurization (72 C for 15 sec)

60
Q

Pasteurization kills

A

Coxiella burnetii, the cause of Q fever

61
Q

Temp for food preservation

62
Q

Long term storage of cultures:

A
  1. -70 in glycerol

2. Lyophilization or freeze-drying

63
Q

Filters that can remove microbial cells

A

Micropore filters (0.2 um)

64
Q

Force air through HEPA filters removing >99.9% of airborne particulate material 0.3 um in size or larger

A

Laminar air flow biological safety cabinets

65
Q

Used for surface sterilization for has poor penetrating power

A

Ultraviolet light

66
Q

Used to irradiate foods and other heat-sensitive items. Has high penetrating power.

A

Gamma rays, e- beams, and x-rays

67
Q

Factors influencing the efficacy of a given chemical agent:

A
  1. The presence of organic matter
  2. Kinds of organisms present
  3. Corrosiveness
  4. Stability, odor, and surface tension
68
Q

Phenol coefficient test

A

Compares the effectiveness of disinfectants

69
Q

Commercial disinfectants and antiseptics

A
  • ethanol
  • iodine
  • chlorine
  • ethylene oxide
70
Q

Mechanisms of resistance to disinfectants:

A
  1. Altering fatty acid synthesis protein normally targeted by triclosan
  2. Producing membrane-spanning, multidrug efflux pumps
  3. Forming multispecies biofilms, which offer collaborative protection
71
Q

The use of one microbe to control the growth of another

A

Biocontrol

72
Q

Aims to treat infectious diseases with a virus targeted to the pathogen

A

Phage therapy

Micro (5 decks)

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