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VMCB 121 Lecture > 2: Cultivation of Bacteria > Flashcards

2: Cultivation of Bacteria Flashcards

1
Q

raw materials required for metabolism and reproduction

A

nutrients

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2
Q

events used in biosynthesis and energy production

A

nutrition

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3
Q

2 types of nutritional requirements for living organisms

A

mineral nutrients (micro-nutrients and macro-nutrients)

growth factors

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4
Q

give 5 examples of micro-nutrients

A

cobalt
copper
manganese
molybdenum
nickel
selenium
tungsten
vanadium
zinc

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5
Q

give 5 examples of macro-nutrients

A

oxygen**
hydrogen**
carbon
nitrogen**
phosphorous
sulfur
potassium
magnesium
sodium
calcium
iron
carbon**

carbon, nitrogen, and water as needed in highest quantities

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6
Q

3 groups of growth factors

A

amino acids
purines and pyrimidines
vitamins (riboflavin, biotin, niacin, B6, K, thiamin etc.)

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7
Q

2 classifications of microorganisms according to CARBON source

A

autotroph and heterotroph

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8
Q
  • producers,
  • photosynthetic
  • use CO2 and H2O
  • sunlight as energy
A

autotrophs

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9
Q
  • require preformed food
  • digestive and absorptive
  • most microbes
A

heterotrophs

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10
Q

2 classifications of microorganisms according to ENERGY source

A

chemotrophs
phototrophs

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11
Q
  • obtain energy by oxidizing electron donor via respiration (i.e., oxidative phosphorylation and others)
A

chemotrophs

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12
Q
  • capture protons in order to acquire energy via phototrophy (i.e., photophosphorylation etc.)
A

phototrophs

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13
Q

4 types of organism in general (combination of energy and carbon source)

A

photoautotroph
- energy from light
- carbon from CO2

chemoautotroph
- energy from oxidation of inorganics
- carbon from CO2

photoheterotroph
- energy from light
- carbon from preformed organic food

chemoheterotroph
- energy from oxidation of organics
- carbon from preformed organic food

(see module for diagram)

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14
Q

2 classification of microorganisms according to ELECTRON source

A

lithotrophs - reduced inorganic compounds as electron donors

organotrophs - organic compounds as electron donors

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15
Q

4 physical requirements for microbial growth

A

temperature
pH
oxygen and carbon dioxide
hydrostatic pressure

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16
Q
  • most important factor that determines the rate of microbial growth, multiplication,
    survival and death of all microorganisms
  • directly proportional to rate of enzyme reaction
A

temperature

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17
Q

3 cardinal temperatures

A

minimum - lowest temp. at which organisms grow

optimum - highest growth rate

maximum - highest temp. at which growth occurs

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18
Q

effects of temperature on the following levels:
- very low temperature
- lower than optimum temperature
- higher than optimum temperature
- very high temperature

A

very low temperature - very slow metabolic rates, cells survive longer

lower than optimum temperature - faster enzymatic rates and growth

higher than optimum temperature - DNA, RNA, and other cell components are irreversibly denatured, growth rate drops to zero

very high temperature - microorganism dies

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19
Q

4 classifications of microorganisms according to TEMPERATURE

A

psychrophiles/cryophiles
mesophiles
thermophiles
hyperthermophiles

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20
Q
  • microorganisms that are able to grow at -20° C to 10° C
  • e.g., Pseudomonas, Flavobacterium, and Alcaligenes
A

psychrophiles/cryophiles

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21
Q
  • grows best in moderate temperatures
  • from 20° C to 45° C
  • most microorganisms
  • e.g., E. coli, Streptococcus pneumoniae, etc.
A

mesophiles

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22
Q

body temperature pathogenic to humans

A

37° C

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23
Q
  • heat-loving microorganisms
  • min: 45° C
  • optimum: 50° C to 80° C
  • most prokaryotes in volcanic areas
  • e.g., Thermus aquaticus, Geogemma
    barrosii, etc.
A

thermophiles

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24
Q
  • thrives in extremely hot environments
  • from 80° C to 113° C
  • CM has high levels of saturated fatty acids to retain shape
  • e.g., Sulfolobus solfataricus, Methanococcus jannaschii, Thermotoga, etc.
A

hyperthermophiles

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25
Q
  • the negative logarithm of Hydrogen ion concentration
A

pH

drastic variations of cytoplasmic pH disrupts enzyme activities and membrane transport protein activities (leading to inhibition)

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26
Q

4 classifications of microorganisms according to pH

A

acidophiles: 0 - 5.5
neutrophiles: 5.5-8.0
alkalophiles: 8-14

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27
Q

identify the pH range for:
- optimum microbial growth
- most bacteria
- molds and yeasts

A

optimum microbial growth: 6-8
most bacteria: 4-9
molds and yeasts: 5-6

28
Q

2 principal gases that affect the growth of microbial cells

A

oxygen and carbon dioxide

29
Q

4 classifications of microorganisms according to OXYGEN requirement

A

**aerobes - survive and grow in an
oxygenated environment (standard air: 21%)

**anaerobes - poisoned by and do not use oxygen
- types:
a. tolerant anaerobes - tolerant to low oxygen concentrations (can be highly or moderately oxygen tolerant)
b. Strictly anaerobes - killed by brief exposure to oxygen

** facilitative anaerobes - do not require oxygen for growth although may use it for energy production if available (e.g., via fermentation)
- e.g., E. coli and yeast

**microaerophiles - grow best at 1-15% oxygen levels (intolerant to normal air with 21% oxygen)
- high susceptibility to superoxide radicals and hydrogen peroxide

30
Q

pressure exerted on the cells by the
movement of water resting on top of them

A

hydrostatic pressure

31
Q
  • pressure-dependent microbes that need a high-pressure environment in order to grow
  • e.g., piezophiles
A

barophiles

32
Q

method of multiplying microorganisms by letting them grow and reproduce in artificial
culture media under controlled laboratory conditions or set-up

A

bacterial cultivation

33
Q

inoculating the bacteria in a
pre-determined culture medium and
growing in a laboratory controlled
environment

A

in vitro culture

34
Q

nutrient material prepared for the growth of microorganisms in a laboratory

A

culture media

35
Q

when microbes are introduced into a culture medium to initiate growth

A

inoculum

36
Q

microbes that grow and multiply in or on a culture medium

A

culture

37
Q

3 main purposes of bacterial cultivation

A

To grow and isolate all bacteria in an infection.

To identify cause of infection and contaminants or colonizers.

To allow identification and characterization of bacteria.

38
Q

7 basic resources in culture media

A
  • distilled water (70-85%)
  • carbon
  • energy (0.5%) (in form of nitrate, sulfide, or glucose)
  • nitrogen
  • mineral
  • growth factors (AAs and vitamins)
  • Oxygen, moisture, pH, and temperature
39
Q

5 components of culture media

A
  1. agar (or agar-agar) - long chain polysaccharide
  2. peptone - complex mixture of partially digested proteins
  3. yeast extract - source of growth factors
  4. malt extract - maltose, starch, dextrins, glucose
  5. blood and serum - from human or animal for enriching (10% concentration)
40
Q

3 types of culture media according to PHYSICAL STATE or CONSISTENCY

A

a. liquid media - peptone and NaCl as main ingredients e.g., broths

b. solid media - agar into liquid media
- for isolating bacteria and determining characteristics of colonies

c. semi-solid media - 0.5% or less agar for cultivation of microaerophilic bacteria and determining their motility

41
Q

3 types of culture media according to their chemical composition

A

simple media - general purpose; basic nutrients

complex media - common ingredient: peptone (some ingredients with unknown composition)

synthetic or chemically-defined media - from pure chemical substances with known composition
- for special studies such as metabolic requirements of microorganisms

42
Q

8 types of culture media according to FUNCTION

A

basal media
enriched media
enrichment media
selective media
differential media
indicator media
transport media
anaerobic media

43
Q
  • simplest and most common medium in diagnostic laboratories
  • for non-fastidious bacteria
  • e.g., nutrient agar, nutrient broth, peptone water
A

basal media

44
Q
  • addition of substances like blood, chocolate, or serum to a basal medium
  • for fastidious bacteria
  • e.g., blood agar, chocolate agar, Lowenstein-Jensen agar, Bordet-Gengou agar, Loeffler’s serum slope, and Dorset’s egg medium
A

enriched media

45
Q
  • usually liquid medium that inhibits
    the growth of unwanted bacteria and favors the growth of wanted bacteria
  • e.g., tetrathionate broth, selenite F (feces) broth, and alkaline peptone water
A

enrichment media

46
Q
  • solid medium which inhibits the growth of unwanted bacteria but favors the growth of wanted bacteria
  • e.g., DCA agar, TCBS agar MacConkey, Tellurite
A

selective media (isolating from mixed culture)

47
Q
  • reagents or supplements which when incorporated into culture media may allow differentiation of various kinds of bacteria
  • e.g.,
    blood agar (both differential and enriched) - differentiates hemolytic and nonhemolytic bacteria

Nagler’s medium - for lecithinase activity

MacConkey agar (differential and selective) - for inhibiting growth of gram-positive bacteria

A

differential media

48
Q
  • media with indicator which changes color
  • e.g., Wilson-Blair medium, potassium tellurite, and MacConkey agar
A

indicator media

49
Q
  • holding medium designed to preserve the
    viability of microorganisms in the specimen but not allow multiplication
  • e.g., Cary-Blair media, Amies media, Stuart media
A

transport medium

50
Q
  • media are used to grow anaerobic
    organisms and contain reducing substances
  • e.g., Thioglycollate broth and Cooked meat broth or RCM broth
A

anaerobic media

51
Q

6 types of aerobic culture methods

A

Streak Plate Culture
Lawn Culture
Stroke Culture
Stab Culture
Pour Plate Culture
Liquid Culture

52
Q
  • aerobic culture method routinely employed for the isolation of bacteria in pure culture from clinical specimens
A

quadrant streak plate method

53
Q
  • aerobic culture prepared by flooding the surface of the plate with a liquid culture or suspension of the bacterium, pipetting off the excess inoculum and incubating
    the plate
A

lawn culture method

54
Q
  • aerobic method: slopes are
    seeded by lightly smearing the surface of agar with loop in a zigzag pattern taking care not to cut the agar
A

stroke culture method (same as our first inoculation in vmcb lab)

55
Q
  • aerobic method: nutrient gelatin or glucose agar is punctured with a long, straight, charged wire into the center of the medium and withdrawing it in the same line to avoid splitting the medium
A

stab culture method

56
Q
  • aerobic method: sample is spread evenly over surface of agar using sterile glass spreader
  • results to surface colonies only
A

spread-plate method

57
Q
  • aerobic method: sterile medium is added and mixed with inoculum
  • results to both subsurface and surface colonies
A

pour-plate method

58
Q
  • aerobic method: inoculated
    by touching with a charged loop or by adding the inoculum with pipettes
    or syringes
A

liquid culture method

59
Q

2 disadvantages of the liquid culture method

A

does not provide a pure culture from mixed inocula—the major disadvantage

identification of bacteria is not possible

60
Q

these microorganisms will not grow from small inocula unless oxygen is absent and the pH of the medium is low

A

obligate anaerobes

61
Q

6 methods of anaerobiosis

A
  • Production of a vacuum
  • Displacement of oxygen by other gases
  • By absorption of oxygen by chemical or biological methods
  • By displacement and combustion of oxygen
  • By reducing agents
  • Other anaerobic culture systems
62
Q

anaerobic method: attempted by incubating cultures in a vacuum desiccator, but proved to be unsatisfactory because some oxygen is always left behind

A

production of a vacuum

63
Q

anaerobic method: inoculated plates are placed inside a large airtight container and a lighted candle kept in it before the lid is sealed

A

Displacement of oxygen by other gases (via candle jar)

64
Q
  • anaerobic method: the method of choice for preparing anaerobic jars
  • in the form of disposable packet of aluminum foil containing pellets of sodium borohydride and cobalt chloride and of citric acid and sodium bicarbonate
A

Gaspak (absorption of oxygen by chemical or biological methods)

65
Q
  • anaerobic method: jar used to displace and combust oxygen
A

Mcintosh-Filde’s anaerobic jar

66
Q
  • anaerobic method: use of ***** agents whose effectiveness can be increased by making a liquid medium semisolid with agar 0.05 to 0.1 percent
  • e.g., thioglycollate broth, cooked meat broth (CMB) or Robertson’s cooked meat (RCM)
A

by reducing agents

67
Q

5 ways to preserve bacterial cultures

A

refrigeration - short-term

deep freezing - quick-frozen, last several years

lyophilization (freeze drying) - quick-frozen then vacuumed to remove water

cold storage

drying methods

VMCB 121 Lecture (5 decks)

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