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Micro > Lab Quiz 3 > Flashcards

Lab Quiz 3 Flashcards

1
Q

What 3 things contribute to the ubiquity of microorganisms?

A

small size
rapid reproduction
metabolic diversity

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2
Q

What fungus can produce aflatoxins?

A

Aspergillus flavus

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3
Q

What was the suspending medium used for spices?

A

0.85% NaCL

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4
Q

What type of agar was used for spices?

A

TSA

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5
Q

Procedure for spices

A

suspend about 100 mg of spice in a tube of 10 mL suspending medium and mix
Perform a serial dilution (10-1, -2, -3)
Transfer 1 ml from each dilution to sterile Petri dishes
Add 20mL molten TSA
Incubate at 30C
Examine for 2 lab periods

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6
Q

Procedure for other location

A 
Swab a location with sterile swab
Inoculate a third of a TSA plate
Use sterile loop to streak for isolation
Incubate at temperature corresponding to location
Examine for 2 lab periods
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7
Q

What’s an example of a social bacteria?

A

myxobacteria

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8
Q

How do myxobacteria kill prey?

A

releasing lytic enzymes and antimicrobial compounds

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9
Q

What happens to Myxobacteria xanthus upon starvation?

A

vegetative cells aggregate into multicellular fruiting bodies
a subpopulation of fruiting bodies differentiates into dormant, stress resistant myxospores

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10
Q

What species is morphologically between bacteria and fungi?

A

Actinomycetes

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11
Q

What are the features of Actinomycete colonies

A

extensive, branched mycelium that may give rise to conidiospores
small, compact, soft to leathery

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12
Q

What do the hyphae of Actinomycete develop into?

A

very fine “vegetative” or “submerged” mycelium

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13
Q

What does the feeding mycelium of Actinomycete become (sometimes)?

A

aerial mycelium that is thicker and may give a powdery appearance to the colony

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14
Q

What causes a colony to look powdery?

A

production of conidiospores

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15
Q

What genus is a major source of antibiotics?

A

Streptomyces

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16
Q

Photosynthetic microbes

A

Cyanobacteria, Green and Purple bacteria

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17
Q

Cyanobacteria perform

A

oxygenic photosynthesis

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18
Q

Green and purple bacteria perform __

A

anoxygenic photosynthesis

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19
Q

Green and purple bacteria can’t perform oxygenic photosynthesis because __

A

they are unable to utilize water as an electron source

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20
Q

what pigment do cyanobacteria use to collect sun energy

A

chlorophylls

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21
Q

what pigment do green and purple bacteria used to collect sun energy

A

bacteriochlorophylls

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22
Q

What are two accessory pigments used by photosynthetic bacteria?

A

carotenoids

phycobiliproteins

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23
Q

green and purple sulfur bacteria are ____ (relationship to oxygen)

A

obligate anaerobes

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24
Q

purple nonsulfur bacteria are ___ (relationship to oxygen)

A

facultative anaerobes

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25
Q

What is the purpose of Winogradsky’s column?

A

to illustrate how bacteria develop in certain habitats in response to appropriate environmental conditions

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26
Q

Sequence of equations - Wino column

A

organic matter + O2 -> organic acids + CO2
organic acids + SO4 -> H2S + CO2
H2S + CO2 -(light)-> carbohydrate + S

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27
Q

What occurs in the first phase of the Wino column?

A

hetertrophic microbes oxidize organic matter and consume O2, making it anaerobic

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28
Q

What occurs in the second phase of the Wino column?

A

anaerobic sulfate-reducing bacteria reduce sulfates and sulfites to hydrogen sulfide (organic acids act as electron donors)

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29
Q

What occurs in the third phase of the Wino column?

A

H2S is used as an electron donator to reduce CO2 into carbohydrates by photosynthetic organisms such as purple and green sulfur bacteria (light is required)

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30
Q

What occurs in the fourth phase of the Wino column?

A

H2S is used as an electron donator to reduce CO2 into carbohydrates by photosynthetic bacteria such as purple non-sulfur bacteria (light is required)

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31
Q

What’s present in the aqueous layer of the Wino column at the end of the experiment?

A 
AEROBIC
protozoans
fungi
algae
aerobic bacteria
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32
Q

What’s present in the mud layer of the Wino column at the end of the experiment?

A

ANAEROBIC

photosynthetic bacteria

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33
Q

Purple and green sulfur bacteria present in the Wino column

A

Chromatin

Chlorobium

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34
Q

Purple non-sulfur bacteria present in the Wino column

A

Rhodospirillum
Rhodopseudomonas
Rhodomicrobium

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35
Q

Are purple non-sulfur bacteria present in the upper portion of the Wino column? How can you tell? How are they able to function?

A

Yes, there will be a rust colored zone, they use organic matter as an electron donor

36
Q

What type of bacteria is present throughout the Wino column?

A

Heterotrophic

37
Q

What are the two possible forms of selection for choosing specific growth conditions?

A

repressive selection

enrichment selection

38
Q

What is repressive selection?

A

repressing the growth of interfering microbes while permitting the growth of the culture sought

39
Q

What is enrichment selection?

A

encouraging the growth of the sought after microbe so it will out compete its competitors

40
Q

Why doesn’t reducing the sample size help to avoid contamination?

A

The organism sought after is usually a minor part of the population

41
Q

What is differential plating?

A

isolation from a mixed culture by making it easier to recognize the culture sought without introducing any inhibitory or enrichment substance

42
Q

What are possible selective influences in media?

A

temperature of incubation
pH
oxygen

43
Q

Habitat of Escherichia coli

A

lower intestinal tract

44
Q

Do E. coli have endospores?

A

no

45
Q

What components of MacConkey makes it selective for gram-negative bacteria?

A

crystal violet and bile salts

46
Q

What components of MacConkey allows it to differentiate between fermenters of lactose and nonfermenters of lactose?

A

neutral red indicator

47
Q

Habitat of Enterococcus faecalis

A

lower intestinal tract

48
Q

Do E. faecalis have endospores?

A

no

49
Q

What components of Colistin-Nalidixic Acid agar makes it selective against gram-negative bacteria

A

two antibiotics

50
Q

What kind of hemolysis is E. faecalis capable of?

A

gamma

51
Q

What kind of hemolysis is Staphylococcus capable of?

A

gamma or beta

52
Q

Do Staphylococcus have endospores?

A

no

53
Q

What do yellow colored colonies on Mannitol Salts plate indicate?

A

ability to ferment mannitol

54
Q

Habitat of Bacillus

A

soil

55
Q

Habitat of Pseudomonas

A

soil

56
Q

Do Bacillus have endospores?

A

yes

57
Q

Do Pseudomonas have endospores?

A

no

58
Q

What does Pseudomonas enrichment have that makes it selective?

A

p-hydroxybenzoate

59
Q

What’s the difference between Pseudomonas agar F and agar P plates?

A

F produces yellow-green pigment that can be detected under UV light
P produces blue-green pigment that can not be detected under UV light

60
Q

What form of nitrogen can Azotobacter reduce?

A

atmospheric nitrogen (N2) to ammonia

61
Q

When do Azotobacter produce capsules and what do they do?

A

when growing as N2 as nitrogen source; to protect nitrogenase

62
Q

When do Azotobacter produce cysts and what do they do?

A

when media becomes deficient in carbohydrates and other nutrients; germinate to vegetative cells when conditions become favorable

63
Q

What makes Ashby’s plate selective for nitrogen-fixing bacteria?

A

absence of nitrogen, so the only source is atmospheric nitrogen

64
Q

Are E. coli motile?

A

yes

65
Q

Are Azotobacter motile?

A

variable

66
Q

Are Staphylococcus motile?

A

non

67
Q

Are Enterococcus motile?

A

no

68
Q

Are Pseudomonas motile?

A

yes

69
Q

Are Bacillus motile?

A

yes

70
Q

How is the DNase test agar used?

A

distinguish Serratia from Escheerichia and Enterbacter

Serratia produces an extracellular deoxyribonuclease that can be detected as a violet colored zone

71
Q

How is the catalase test used?

A

differentiate Staphylococcus (catalase +) from Streptococcus (catalase -)

72
Q

How is the oxidase test used?

A

detects cytochrome oxidase enzyme

E. coli, Enterobacter, and Serratia are oxidase +

73
Q

How is the indole test used?

A

differentiates E. coli (indole +) and Enterobacter (indole -)

74
Q

What does alpha hemolysis look like on BAP?

A

greenish discoloration around colony

75
Q

What does beta hemolysis look like on BAP?

A

transparent area around colony

76
Q

What is alpha hemolysis?

A

partial activity

77
Q

What is beta hemolysis?

A

complete activity

78
Q

What is gamma hemolysis?

A

no activity

79
Q

What does gamma hemolysis look like on BAP?

A

no change in agar

80
Q

Which species was tested on a Mannitol salt plate?

A

Staphylococcus

81
Q

Which species was initially isolated on BAP?

A

Staphylococcus

82
Q

Which species was isolated on MAC plate?

A

E. coli

83
Q

Which species was isolated on CNA plate?

A

E. faecalis

84
Q

Which species was tested on DNase plate?

A

E. coli

85
Q

Which species was tested with an indole test?

A

E. coli

86
Q

What was the TTC deep test performed for?

A

to detect motility (presence of flagella)

87
Q

Which species was tested with TTC deep?

A

E. coli
E. faecalis
Bacillus
Staphylococcus

Micro (15 decks)

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