Lecture 9

Question 1

complex media

Answer 1

we are not aware of every chemical in the media

Question 2

defined media

Answer 2

every chemical in media is known and quantified

-can be tailored to requirements of one species

Question 3

different medias

Answer 3

-broth, plates, slants, deeps

Question 4

broth

Answer 4

• grow large quantities of culture

- difficult to check for purity

Question 5

plate

Answer 5

• readily score and separate colonies

- does not store well

Question 6

slants

Answer 6

• mini plates for storage with smaller volume

- difficult to check for purity

Question 7

semi-solid deeps

Answer 7

• can score motility and oxygen requirements, also storage

- difficult to check for purity

Question 8

agar

Answer 8

carbs from cell walls of red algae

-melts at 85C and solidifies at 40C (separately)

Question 9

basic plate

Answer 9

• nutrient agar

- suitable for non-fastidious (non picky) organisms

Question 10

selective media

Answer 10

encourage growth of some bacteria while preventing growth of others

Question 11

differential media

Answer 11

will produce different visual cues as to the type of organism growing

Question 12

enrichment media

Answer 12

a type of selective media used to allow proliferation of rare bacteria in a mixed population

Question 13

MacConkey Agar

Answer 13

• selective and differential
• select against gram +
• contains lactose and pH indicators

Question 14

fermenters in macconkey plates

Answer 14

-turn purple

Question 15

non-fermenters in macconkey plate

Answer 15

-stay creamy

Question 16

acid diffusion in macconkey plate

Answer 16

-colours plate

Question 17

MSA (Mannitol Salt Agar)

Answer 17

• selective and differential
• contains mannitol
• useful for detecting staph

Question 18

fermenters MSA plates

Answer 18

turn yellow

Question 19

non-fermenters MSA plates

Answer 19

stay red

Question 20

blood agar plates (BAP)

Answer 20

• enrichment and differential
• sheep blood
• test for hemolytic activity

Question 21

hemolysis may be enhanced in…

Answer 21

low oxygen environments

Question 22

beta BAP

Answer 22

clearing

Question 23

alpha BAP

Answer 23

discolouration in or under colony

Question 24

gamma BAP

Answer 24

no hemolysis

Question 25

Saboraud Dextrose Agar (SDA)

Answer 25

• similar to nutrient agar, but high amount of glucose

- sugar and acidic pH selects for yeasts and molds

Question 26

SIM Deep/Diagnostic Tubes

Answer 26

• differential
• sulfur reduction
• indole production
• motility

Question 27

sulfur reduction

Answer 27

if H2S produced, reacts with Ammonium Iron III Sulfate and turn black

Question 28

indole production

Answer 28

• if tryptophan is metabolized

- can be detected by dripping Kovaks reagent on top after incubation (red=positive)

Question 29

motility

Answer 29

if cells grow away from stab the cells are motile

Question 30

oxidase test

Answer 30

-can the organism use oxygen to generate ATP?

Question 31

oxidase +

Answer 31

blue/purple

Question 32

oxidase -

Answer 32

no change

Question 33

dichotomous keys

Answer 33

a series of yes/no questions to identify an unknown

-starts general and becomes more specific

Question 34

dichotomous keys priority is given to tests that are…

Answer 34

• universal
• quick
• simple

Question 35

biochemical identification systems

Answer 35

• several tests at once
• easily identify medically important bacteria
• • and - results are scored and looked up in booklet

Question 36

DNA testing

Answer 36

extracting bacterial DNAand testing various procedures

Question 37

antibody testing

Answer 37

assaying if specific antibodies bind unknown cells to determine identirty

Question 38

logarithmic growth

Answer 38

exponential growth of bacteria