Assessment #3 Flashcards

Bacterial Nutrition

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1
Q

culture medium

A

a nutrient material prepared for the growth of microorganisms in a laboratory

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2
Q

inoculum

A

microbes that are introduced into a culture medium

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3
Q

culture

A

the microbes that grow and multiply in or on a culture medium

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4
Q

examples of criteria that a culture medium must meet

A
  • right nutrients
  • sufficient moisture
  • proper pH
  • suitable level of oxygen
  • sterile
  • proper temperature
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5
Q

agar

A
  • a complex polysaccharide derived from a marine alga (agarophytes)
    • a polymer of galactose and galacturonic acid
    • isolated from seaweed agarocytes in the seaweed
  • a solidifying agent added to the medium to create a solid medium
  • it is NOT a nutrient itself
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6
Q

agar concentrations

A
  • normal agar: 1.5% (weight per volume)
    • eg - 15g per liter of water
  • soft agar: 0.5% (weight per volume)
    • often used for overlays
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7
Q

why can most bacteria not digest agar?

A
  • most bacteria lack agarase, an enzyme that can digest agar
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8
Q

chemically-defined medium

A
  • a medium whose exact chemical composition is known
  • also known as a synthetic medium
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9
Q

fastidious organisms

A

organisms that require many growth factors

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10
Q

complex medium

A
  • a medium whose exact chemical composition is basically unknown
  • often made up of yeast, meat, protein, and plant extracts at various amounts
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11
Q

semi-defined medium

A
  • a medium whose chemical composition is partially known
  • between chemically-defined medium and complex medium
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12
Q

liquid medium

A

a complex medium in liquid form

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13
Q

reducing medium

A
  • medium that contains ingredients that chemically combine with dissolved oxygen and deplete the oxygen in the culture medium
  • used to grow obligate anaerobes
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14
Q

uses of bacterial media

A
  1. enrichment
  2. selective
  3. differential
  4. (selective and differential)
  5. maintenance
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15
Q

bacterial media for enrichment

A
  • allows organisms to grow on the basis of what they prefer
  • designed to increase numbers of desired microbes to detectable levels
  • Winogradsky column
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16
Q

bacterial media for selection

A
  • adds an inhibitory agent that will prevent some bacteria from growing while allowing others to grow
  • suppresses unwanted microbes and encourages desired microbes
  • eg - antibiotics, basic dyes, bismuth sulfite agar
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17
Q

bacterial media for differentiating

A
  • addition of something that will differentiate (not inhibit) between microbes
  • eg - milk agar, pH indicator, blood agar
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18
Q

bacterial media for maintaining

A
  • used to maintain and preserve microorganisms for long-term
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19
Q

bacterial media for selecting and differentiating

A
  • supresses unwanted microbes and differentiates colonies of desired microbes from each other
  • eg - MSA (mannitol salt agar), EMB (eosin-methylene blue agar)
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20
Q

bacterial nutrition patterns

A
  1. energy source
  2. carbon source
  3. electron donor source (reducing power)
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21
Q

chemotrophs

A
  • obtain energy from chemicals
22
Q

phototrophs

A
  • energy source is electromagnetic radiation - sunlight
23
Q

heterotrophs

A
  • organic carbon source
    • C w/H = organic
24
Q

autotrophs

A
  • inorganic carbon source
    • C w/o H = inorganic
      • eg - carbon dioxide
25
Q

organotroph

A
  • an organic compound is the electron donor source
26
Q

lithotroph

A
  • inorganic electron donor source
27
Q

which nutritional classification are humans?

A

chemoheteroorganotrophs

28
Q

which nutrition classifications are bacteria?

A

bacteria can be combinations of any of these three sources, resulting in high diversity

29
Q

who invented the petri dish?

A

Julius Richard Petri

30
Q

who developed bacteriological media?

A

Robert Koch

31
Q

who discovered agar?

A
  • Walther and Fannie Heese
  • Both worked in Koch’s lab
    • Koch took credit for their discovery
32
Q

what was the first type of bacteria cultured with agar?

A
  • Mycobacterium tuberculosis
  • It was the first time that it had ever been cultured
  • Cultured by Koch
33
Q

What was the principal reason for developing methods to culture and isolate microorganisms?

A

The principal reason was to identify bacterial agents of disease

34
Q

Vibrio cholerae

A
  • Causes cholera
35
Q

Bacillus anthracis

A
  • Causes anthrax
36
Q

Mycobacterium tuberculosis

A
  • Causes tuberculosis
37
Q

Corynebacterium diphtheriae

A
  • Causes diphtheria
38
Q

Biogeochemical cycles

A
  • The ways in which an element or compound moves between various living and nonliving forms and locations in the biosphere
  • There are six elements that are principally involved in these cycles.
39
Q

Essential elements of life

A
  • CHNOPS
    • carbon
    • hydrogen
    • nitrogen
    • oxygen
    • phosphorus
    • sulfur
  • Involved in the biogeochemical cycles
  • Most exist in both organic and inorganic forms
40
Q

Examples of inorganic and organic nitrogen sources

A
  • Inorganic
    • ammonia
  • Organic
    • amino acids
41
Q

Examples of inorganic and organic sulfur sources

A
  • Inorganic
    • hydrogen sulfate, sulfite, sulfate
  • Organic
    • sulfur-containing amino acids
      • enable junction between N and S cycles
42
Q

Examples of inorganic and organic sources of phosphorus

A
  • Inorganic
    • phosphate
  • Organic
    • biomolecules
43
Q

What are the major trace elements? What are their functions?

A
  • Magnesium (Mg)
    • stabilizes the negative charge of the cell membrane/cell wall
  • Calcium (Ca)
    • balances ionic strength
    • maintains the equilibrium of potassium between external and internal
  • Iron (Fe)
    • found within the proton chain
44
Q

What are the minor trace elements? What are their functions?

A
  • Boron (B)
  • Nickel (Ni)
  • Zinc (Zn)
  • Molybdenum (Mo)
  • Serve as cofactors for specific enzymes
    • eg - nitrogenase and nitrate reductase require Mo to be synthesized and to function
45
Q

The 3 cardinal temperatures of growth

A
  1. minimal temperature - the lowest temperature that is required for growth
  2. optimum temperature - the ideal temperature
    • skewed towards the maximum
  3. maximum temperature - the highest temperature that allows growth
46
Q

Psychrophiles

A
  • Range = -5 to 20 C
  • Optimum = 5-10 C
47
Q

Psychrotrophs

A
  • Optimum = 15 to 20 C
  • Can grow at temperatures below 0 C (like psychrophiles), but have a higher optimal temperature
    • Therefore also known as facultative psychrophiles
48
Q

Mesophiles

A
  • Range = 15-45 C
  • Optimum = 30-37 C
  • The majority of organisms
  • High diversity
49
Q

Thermophiles

A
  • Higher temperature range of 45-80 C
50
Q

Extremophiles

A
  • Highest temperature range
  • Optimal = >80 C
51
Q
A