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Lab Final Flashcards

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1
Q

what is the most important nutrient for bacteria to have

A

carbon (autotroph versus heterotroph)

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2
Q

what influence does temperature have on bacterial growth

A

influences the rate of chemical reactions in the cell

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3
Q

what are the two main types of bacterial cultivation

A

defined media and complex media

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4
Q

how are defined media composed

A

composed of known quantities of chemically pure and specific organic/inorganic compounds. (very specific recipe)

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5
Q

what are two examples of defined media

A

inorganic synthetic broths or glucose salt broths

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6
Q

what are complex media

A

exact chemical composition not known. made from animal and plant tissue extracts.

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7
Q

what are two examples of complex media

A

nutrient broths and yeast extract broths

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8
Q

what is a nutrient broth made of

A

peptone and beef extract

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9
Q

what is yeast extract broth made of

A

nutrient broth (peptone and beef extract) plus yeast

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10
Q

what does turbidity indicate

A

bacterial growth

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11
Q

what are selective media

A

used to isolate specific groups of bacteria

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12
Q

how do selective media work

A

chemicals to inhibit growth of one organism but allows growth of another organism

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13
Q

what are three examples of selective media

A

phenylethyl alcohol (pea), crystal violet, sodium chloride

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14
Q

what are differential/selective media

A

will produce a change in appearance of bacterial growth on or around the colonies, and also can inhibit growth of some organisms

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15
Q

what are examples of differential/selective media

A

MSA, MacConkey’s, Eosin-methylene blue

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16
Q

how does MSA work

A

inhibits by salt concentration, mannitol (to ferment) and a pH indicator for detecting fermentation (yellow -)

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17
Q

how does macconkeys work

A

does not allow gram positive to grow, fermentation of lactose with ph indicator

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18
Q

how does eosin-methylene blue work

A

fermentation of lactose, doesnt grow gram positive

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19
Q

how does PEA work

A

(phenylethyl alcohol) only allows gram positive growth

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20
Q

what are enriched media

A

media with highly nutritious materials

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21
Q

what are some nutrients used in enriched media

A

blood, serum, yeast

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22
Q

how do most microorganisms obtain their energy

A

through a series of orderly and integrated enzymatic reactions leading to biooxidation of carbohydrates

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23
Q

why would an organism use one carbohydrate over another

A

varying enzyme compliments

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24
Q

what is the function of carbohydrate tests

A

to determine fermantative pathways

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25
what is the pathway used to describe the fermantation of carbohydrates
glycolytic pathway
26
one mole of glucose is turned into what
two moles of pyruvic acid
27
how is fermentative degredation achieved
under anaerobic conditions in a fermentation tube with a durham tube
28
what is typically found in a fermentation broth
nutrient broth with a specific carbohydrate and a pH indicator
29
why is there only a specific carbohydrate included in a fermentation broth
determines if the organism can ferment that specific carbohydrate (indicated by the pH indicator)
30
typically if fermentation has occurred, what colour will the broth turn
will turn yellow which is a negative result
31
what are positive and negative results based on acidity
positive is if it is basic, negative if it is acidic
32
what is the longest a broth should go
48 hours is the longest.
33
when should you let a broth go to 48 hours
if not positive after 18-24 hour window, let it go to a seconf period (up to 48 hours)
34
how do you get a negative result in carbohydrate fermentation
when the carbohydrate present is not used, the organism will use the peptones in the nutrient broth, using these causes basic conditions (ammonia)
35
lactose fermentation can distingush between what types of bacteria
enteric and non-enteric
36
what does TSI stand for
triple sugar iron agar test
37
what is the function of a TSI test
differentiate between groups of the enterobacteriaceae. tells fermentation patterns and hydrogen sulfide production
38
what carbohydrate concentration is found in TSI
equal concentrations of lactose, sucrose, and glucose (1%)
39
what pH indicator is found in TSI
phenol red
40
how do you innoculate a tsi slant
stab and streak
41
how is gas production measured in TSI slants
there can be gas bubbles in the media, they can even split the media
42
how can you tell if only glucose production has occurred in TSI slants
red slant, yellow butt, with or without gas production
43
how can you tell if lactose or sucrose production has occurred in a TSI slant
yellow slant, yellow butt, with or without gas
44
how can you tell that no carbohydrate fermentation has occurred in a TSI slant
red slant, red butt
45
what is the window of time for a TSI slant
18-24 hours strictly
46
how can you tell if hydrogen sulfide production has occurred in a TSI slant
the mid section will be black (ferrous sulfate reacting with sodium thiosulfate)
47
what bacteria of medical importance can be found in the enterobacteriaceae
pathogens, occassional pathogens, normal intestinal flora
48
what comprises the IMViC test
indole, methyl red, voges- proskauer, citrate)
49
what is tryptophan used for
ability of a bacterium to hydrolyze tryptophan in the presence of indole
50
what media do you use for indole
SIM
51
how do you detect the presence of indole in SIM agar
by adding Kovac's reagent
52
how do you tell if a positive result for indole in SIM media
after adding kovacs if positive it will turn cherry red
53
what is the time period for indole (SIM)
24-48 hours
54
how much kovacs do you add to a SIM tube to detect indole
about 10 drops
55
what is the major substrate used by all enteric organisms
glucose
56
when doing the methyl red test, if the solution turns red, what result is this
positive result with a lower pH (more acidic)
57
how long do you incubate TSB broth
24-48 hours
58
what is TSB broth used to detect
its the basis for methyl red and voges proskaur tests
59
what does the voges-proskaur test determine
ability of an organism to produce nonacidic or neutral end products
60
what is the reagent used in voges proskaur
barritts reagent
61
how long does it take to perform the voges proskaur test
15 minutes after adding barritts reagent
62
what colour will the solution be if there is a positive result for voges proskaur
dark red
63
how do you perform voges proskaur
use innoculated TSB broth, add 10 drops barritts A and shake immediately, then add 10 drops barritts B and shake immediately. leave for 15 minutes, shaking occassionally
64
what does the citrate test determine
if an organism is able to ferment citrate in the absence of glucose or lactose
65
what is the pH indicator used in the citrate test
bromthymol blue
66
what will a citrate positive test show
growth on the surface of the slant and a blue colouration
67
what will a citrate negative test show
no growth and the media will remain green
68
what is the incubation time for a citrate test
24-48 hours
69
how does a SIM tube show hydrogen sulfide production
black
70
how can you tell motility of an organism
use a SIM tube and when stabbing, if turbidity is outside of the stab line there is motility
71
what pH indicator is found in urease test
phenol red
72
what is urease
attacks amide of urea and forms an alkaline end product
73
how does the urease pH indicator work
urea is split and forms ammonia, this is alkaline and produces a positive red result
74
what is the incubation time for urease
24-48 hours
75
what is decarboxylation
some organisms have decarboxylase enzymes capable of removing the carboxyl group of an amino acid.
76
what is the pH indicator of decarboxylase tests
bromthymol blue
77
what conditions must be met for LDC and ODC
anaerobic conditions (no oxygen)
78
how are anaerobic conditions met in ODC and LDC
adding mineral oil to the surface of the innoculated broth
79
organisms that have deaminase groups can remove what
amino groups from amino acids
80
is performing a phenylalanine test what happens if the organism has phenylalaine deaminase
phenylpyruvic acid will be released and a green colour will result (positive result)
81
what reagent is added to phenylalainine tests
10% ferric chloride solution

Microbiology (6 decks)

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