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Micro > CH7 > Flashcards

CH7 Flashcards

1
Q

Media containing some ingredients of unknown chemical composition are called __________ media.

A

complex

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2
Q

A growth medium that distinguishes among different groups of bacteria on the basis of colony appearance or changes is called a __________ medium.

A

differential

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3
Q

Organisms that grow well at 0°C and have optimum growth temperatures of 15°C or lower are called

A

psychrophiles

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4
Q

All fastidious microorganisms require what growth?

A

extra nutrients (such as vitamins and amino acids)

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5
Q

What reasons for the occurrence of a lag phase in a bacterial growth curve?

A
  • The medium may be different from the previous growth medium so that the cells must synthesize new enzymes to use different nutrients.
  • The cells may be old and depleted of ATP, essential cofactors, and ribosomes that must be synthesized before growth can begin.
  • The organisms may have been injured and require time to recover.
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6
Q

Given a log phase bacterial culture with 1 x 10^6 cells per ml and a generation time of 30 minutes, how long does it take the culture to reach a density of 6.4 × 10^7 cells per ml?

A

3 hours

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7
Q

Microorganisms are most nearly uniform in terms of chemical and physiological properties during __________ phase.

A

exponential

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8
Q

Media in which all components and their concentration are known are called __________ media.

A

defined

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9
Q

For surface cultivation of microorganisms, a sulfated polymer called agar can be extracted from __________ and added to liquid media in order to cause it to solidify.

A

algae

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10
Q

Organisms that do not require oxygen for growth but grow better in its presence are called

A

facultative anaerobes.

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11
Q

The total number of viable microorganisms remains constant in stationary phase because

A

either there is a balance between cell division and cell death or there is a cessation of cell division even though the cells may remain metabolically active.

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12
Q

can be used to isolate pure cultures of bacteria from mixtures

A

streak plate, pour plate and spread plates

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13
Q

regarding tolerance of microbes to osmotic stress

A

cell walls help protect some organisms placed into hypotonic environments

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14
Q

Organisms that are damaged by the normal atmospheric levels of oxygen (20%) but require oxygen at levels of 2–10% for growth are called

A

microaerophiles

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15
Q

Most microorganisms maintain their internal pH

A

near neutral (pH 7 or 7.5)

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16
Q

Organisms that require high levels of sodium chloride in order to grow are called __________ organisms.

A

halophilic

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17
Q

What method can be used to determine the number of viable microorganisms in a sample?

A

measuring colony forming units per ml

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18
Q

At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the log phase culture has a population of 65 million cells. The mean generation time is approximately

A

20 minutes.

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19
Q

Agar is an excellent solidifying agent for microbiological media because

A
  • it is not degraded by most microorganisms.
  • solid agar remains solid until the temperature is raised to 90°C, and liquid agar remains liquid if the temperature is lowered to 45°C.
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20
Q

Cells may enter stationary phase because of

A
  • the depletion of an essential nutrient.
  • the accumulation of toxic waste products.
  • a lack of available oxygen.
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21
Q

What is considered a cardinal growth temperature?

A

minimum, maximum, and optimum temperature

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22
Q

A growth medium that favors the growth of some microorganisms but inhibits the growth of other microorganisms is a __________ medium.

A

selective

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23
Q

Organisms that grow near deep-sea volcanic vents are likely to be

A

thermophilic.

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24
Q

Organisms that grow in the mud under relatively non-turbulent bodies of water are likely to be

A

anaerobes.

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25
Q

Organisms that ignore oxygen and grow equally well in its presence or absence are called

A

aerotolerant.

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26
Q

budding and coenocytic growth

A

binary fission

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27
Q

environmental factors for microbial growth

A
  • pH
  • water and osmotic pressure
  • oxygen
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28
Q

acid loving (0.1-5.4)

A

acidophiles

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29
Q

neutral loving (5.5-8.0)

A

neutrophiles

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30
Q

basic loving (8.0-11.5)

A

alkaliphiles

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31
Q
  • most neutrophiles

- Lactobacillus, sulfer oxidizers, Bacillus

A

bacteria

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32
Q

prefer acidic pH’s

A

fungi and algae

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33
Q
  • narrow ranges

- neutrophiles

A

protozoa

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34
Q

all metabolizing cells require

A

liquid water

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35
Q
  • bacteria, algae, and fungi- have cell walls

- protozoa- contractile vacuoles

A

hypotonic enviornment

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36
Q

example of hypo- and hyper- tonic environments

A

hypo- tap water

hyper- skin, salt lakes

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37
Q
  • plasmolysis

- tolerance

A

hypertonic environment

38
Q

concrete compatible solutes

A

tolerance

39
Q

example of osmotolerant

A

Staphylococcus sp (fungi)

40
Q

require high salt in water

A

osmophiles/halophiles

41
Q
  • grow best below 20 degrees C
  • fridge (slime on meat), oceans, Antarctic soils
  • more on planet than any other phile
A

psychrophile

42
Q
  • medium loving temps (20-40 degrees C)
  • optimum in humans is at 60 degree C
  • human associated
A

mesophiles

43
Q
  • optimum above 65 degree C (40-70 degree C)

- hot water heater, early ones in hot springs and compost

A

thermophiles

44
Q
  • no eukaryotic above 60 degree C
  • optimum above 100 degree C
  • bottom of ocean in volcanic vents
  • need to put in pressurized containers to view
A

hyperthermophiles (extremophiles)

45
Q

how are MOs able to grow at 120 degree C?

A

pressure

46
Q

grow over broad ranges of temps

A

eurythermal microbe

47
Q

grow over narrow ranges of temps

A

stenothermal microbe

48
Q

is oxygen soluble?

A

no

49
Q
  • need O2 to grow
  • algae, most fungi, and protozoa
  • aerobic respiration
  • surface of media, shaking/bubbling
  • hard to culture, MOs can easily infect
A

obligate aerobe

50
Q
  • grow better with O2 (aerobic respiration)
  • can also grow with out O2 (anaerobic respiration)
    - yield less energy and are slower than aerobic
A

facultative anaerobe

51
Q
  • ignore O2 (fermentation or anaerobic resp.)
  • grow slowly
  • Streptococcus sp and Lactobacillus sp
A

aerotolerant anaerobe

52
Q

what are problems with aerotolerant anaerobes?

A

have a lot of growth factor requirements and difficult to grow in culture

53
Q
  • O2 is toxic
  • killed by oxygen
  • agar deep, thioglycollate, anaerobe jar
  • important human associated anaerobe
  • Clostridium sp an Bactericides sp
A

strict anaerobe

54
Q

three ways to culture strict anaerobes

A
  • agar deep (no O2 at bottom)
  • thioglycollate (chemically binds O2)
  • anaerobe jar (Gas Pak)
55
Q
  • most recently discovered
  • require low O2 (2-10%); requires high CO2
  • agar deep, candle jar
  • Helicobactor pylori
A

microaerobe

56
Q

explain how a microaerobe in candle jars

A
  • sample with cork
  • lit candle using up O2 and producing CO2
  • at 5%, O2 candle will go out
  • agar inverted petri plates in a closed jar
57
Q

what are complex medias made of?

A

grind up yeasts for use of complexes

58
Q

examples of solid and liquid medias

A

liquid- broth

solid- agar

59
Q
  • complex polysaccharide from marine algae
  • solidify agent at low [ ] (1.5%)
  • melts at 100 degree C, remains liquid to 40 degree C (can grow thermophiles)
  • not broken down by most MOs
  • expensive
A

agar

60
Q

-contain ingredient (s) that inhibit growth of unwanted MOs

A

selective media

61
Q

contents in selective media

A
  • sugar/pH in Sabourouds agar/ PDA
  • brilliant green dye- Salmonella
  • specific antibodies to inhibit the unwanted
62
Q
  • different kind of MOs look/react differently on medium

- blood agar

A

differential media

63
Q

describe blood agar in differential media

A
  • 5% sheep blood
  • rich for fastidious MOs (a lot of growth factor)
  • different type of hemolysis (hemolozymes)
  • can see different reactions
64
Q

describe MacConkey’s selective and differential agar

A
  • selective- bile salts and crystal violet inhibit gram + bacteria
  • differential- lactose and pH indicator neutral red (MO’s that ferment lactose become pink/red)
65
Q

enrichment media and procedures

A
  • when MO of intrest is present in low proportions
  • medium favors growth of MO of intrest, proportions in the mixture increases
  • repeated transfers of 10 required
66
Q
  • plant/animal cells grown in specialized media

- viruses, parasitic bacteria such as Chamlydia, Rickettsia and some spirochetes

A

tissue/cell culture

67
Q
  • lower proportions of organisms
  • dilute
  • isolation
A

streak plate method

68
Q

diluted sample will be spread on agar

A

spread plate method

69
Q

what is the goal of streak plate and spread plate methods?

A

individual, isolated cells that will grow colonies

70
Q

-used for isolation
-for counting
-mixing MO with cooled agar, then it solidifies
A- better seperations, colonies found through out medium
D- can allow microarofiles at bottom
-tiny colonies deep in agar

A

pour plate method

71
Q
  • agar slants with refrigeration (4 degree C)

- few weeks to months

A

short term storage of cultures

72
Q

different ways for long term storage of cultures

A
  • liquid nitrogen (-196 degree C)
  • ultra freezer (-70 to 120 degree C) electricity can be a problem
  • lyophilization (freeze drying) -best long term storage
73
Q
  • freeze under vacuum, dehydrate, seal
    • no ice crystals because they destroy membranes
  • preference if MO can handle it
A

lyophilization

74
Q

reference for ID, study and patents

A

American Type Culture Collection ATCC

75
Q

no change in number of living cells

A

lag phase

76
Q
  • exponential growth
  • almost all cells are uniform, growing at optimum rate
  • only lasts for a few hours
  • binary fission
A

exponential (log) phase

77
Q
  • bacteria could have run out of living cells is constant

- accumulation of waste products

A

stationary phase

78
Q
  • log death rates

- dying at predicable death rate

A

death phase

79
Q

number of viable MOs remain constant in the _____ and _____ phase of batch cultures growth curve

A

lag and stationary phases

80
Q
  • number of generations per hour
  • E. coli (4.8 generations/hr)
  • M. tuberculosis (.07 generations/hr)
A

k

growth rate

81
Q

number of generations

A

n

82
Q
  • time interval for a cell to divide
  • time for population to double
  • E. coli (12.5 minutes)
  • M. tuberculosis (14 hours)
A

g

generation time

83
Q

what is on the x and y axis of batch culture growth curve (binary fission)

A

x- time

y- log number of viable cells

84
Q

equation for growth rate

A

k= (# of cells start with - # of cells end with) / .3t

85
Q

equation for generation time

A

g= 1/k

86
Q

methods we can use to monitor growth

A
  • microscopic count
  • electric counter (coulter counter)
  • turbidity (cloudiness)
  • cell mass
  • plate/colony count
87
Q
  • little/ no debris present
  • living and dead cells counted (hard to distinguish)-D
  • quick-A
  • require skill
  • motility of MO- D
A

microscopic count

88
Q
  • particle counts
  • large MOs, little debris
  • living and dead cells counted- D
  • expensive- D
  • easy to use, least skill requiring -A
  • used for rbc’s
A

electric counter (coulter counter)

89
Q
  • related to cell [ ], calibrate first
  • living an dead cells counted- D
  • quick- A
  • spectrophotometer
A

turbidity (cloudiness)

90
Q
  • liquid medium
  • very high number or mass required (fungi)
  • collect, wash, dry, weigh
  • living and dead cells- D
A

cell mass

91
Q
  • living cells grow and form colonies
  • time, expensive, clumps of cells
  • appropriate mediums/conditions
  • spread and pour plate methods
A

plate/ colony counts

Micro (15 decks)

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