Culture Media and its Preparation page 1

Question 1

any nutrient, liquid or solid that can be used in the laboratory for growing microorganisms

Answer 1

culture medium

Question 2

polymer made up of subunits of the sugar galactose and is a component of the cell walls of several species of red algae that are usually harvested in eastern Asia and California

Answer 2

agar

Question 3

other use of agar

Answer 3

thickening for soups and sauges, jellies and ice cream

Question 4

firmer and stronger than gelatin

Answer 4

agar

Question 5

it wouldn’t be degraded (eaten) but can be liquified

Answer 5

agar

Question 6

phycocolloid extracted from a group of red-purple marine algae

Answer 6

agar

Question 7

agar is gel at room temp as high as

Answer 7

65 degrees celsius

Question 8

agar melts at

Answer 8

85 degrees celsius

Question 9

Agar solidifies at

Answer 9

32-40 degrees celsius

Question 10

agar is typically used in a final concentration of __________ for solidifying culture media

Answer 10

1-2%

Question 11

Smaller quantities _________are used for

Answer 11

0.05%-0.5% ; motility studies

Question 12

for growth of anaerobes

Answer 12

0.5% w/v

Question 13

for microaerophiles

Answer 13

0.1%

Question 14

specifications for bacteriological grade agar includes

Answer 14

good clarity
controlled gelatin temperature
controlled melting temperature
good diffusion characteristics
absence of toxic bacterial inhibitors
relative absence of metabolically useful minerals and compounds

Question 15

main classifications of media

Answer 15

physical (solid, semi-solid, broth)
chemical composition (synth or non-synth)
functional type (enriched, selective, differential, general purpose, or enumeration)

Question 16

examples of selective at the same time differential media

Answer 16

MacConkey’s Agar
Blood Agar
Mannitol Salt Agar

Question 17

undefined selective media because it inhibits the growth of some organisms (Gram positive bacteria) due to presence of crystal violet and bile salts of peptone base with lactose added.

Answer 17

MacConkey’s Agar

Question 18

also differential meaning that it differentiates or distinguishes groups of bacteria on the basis of some color reaction on or in the media.

Answer 18

MacConkey’s Agar

Question 19

two additives included in MacConkey’s Agar

Answer 19

neutral red
lactose

Question 20

What would be the color of lactose fermenters in MacConkey’s agar?

Answer 20

red/pink

Question 21

What would be the color of non-lactose fermenters in MacConkey’s agar?

Answer 21

colorless

Question 22

gram negative bacilli found in the gastrointestinal of mammals

Answer 22

Enterobacteriaceae

Question 23

most frequently encountered bacteria isolated from many types of clinical specimens

Answer 23

Enterobacteriaceae

Question 24

True or False: Enterobacteriaceae are lactose fermenters

Answer 24

True