types of media

Question 1

Baird-Parker Agar

Answer 1

Staph. aureus

-tellurite-glycine, sodium pyruvate

Question 2

nutrient agar

Answer 2

check the purity of subcultures from isolation

-cultures organisms with no specific nutritional requirements

Question 3

Sabouraud Dextrose agar

Answer 3

An acidic pH medium for the isolation of dermatophytes, fungi, and yeasts. (esp. the cultivation and differentiation of fungi

Question 4

HHD

Answer 4

homofermentative-heterofermentative differential agar

• differentiation of streptococci (hetero) and lactobascilli (homo).
• Bromocresol is added as a pH indicator
• homofermentative=yellow
• heterofermentative=blue-green

Question 5

deMan Rogosa Sharpe (MRS agar)

Answer 5

support good growth of lactobacilli in general

Question 6

Oxytetracycline-Glucose-Yeast Extract Agar (OGYE agar)

Answer 6

selection and enumeration of yeasts and moulds

• The medium uses oxytetracycline as the selective agent (antibiotic).
• neutral pH

Question 7

Acidified Potato Dextrose Agar (APDA)

Answer 7

• isolation and enumeration of yeasts and molds in dairy products
• tartic acid lowers the pH to 3.5 to inhibit bacterial growth
• dextrose: growth stimulant

Question 8

PALCAM agar

Answer 8

• isolation of Listeria monocytogenes
• When PALCAM is being prepared, it requires the addition of a selective supplement which contains: lithium chloride, ceftazidime, polymyxin B and acriflavine hydrochloride, which makes this media highly selective for Listeria.
• Listeria colonies are gray-green on this media with a black precipitate.
• Mannitol fermenting organisms have yellow colonies and/or a yellow halo around their colonies.
• Other organisms that develop on the media may appear as gray colonies with a brown-green halo.

Question 9

Muller Hinton Agar:

Answer 9

• used for antibiotic susceptibility testing
• non-selective and non-differential
• starch which is known to absorb toxins released from bacteria, so that they do not interfere with antibiotics.
• “loose” agar that allows for better diffusion of antibiotics though the media, leading to a truer zone of inhibition measurement.

Question 10

Tryptic Soy Agar (TSA)

Answer 10

• not selective or differential
• digests of soybean meal and casein
• supply organic nitrogen in the form of amino acids and polypeptides, making it highly nutritious
• sodium chloride to maintain osmotic equilibrium

Question 11

Liver Broth:

Answer 11

-liver particles and is recommended for the examination of foods for saccharolytic or putrefactive mesophilic and thermophilic anaerobes.

Question 12

Dextrose Tryptone Broth

Answer 12

-many different organisms that cause spoilage in low- and medium-acid canned food

Question 13

Plate Count Agar:

Answer 13

viable counts

not selective

Question 14

Tomato Serum Media

Answer 14

• Lactobacillus species
• When a more acidic medium is required the pH may be adjusted to approximately 5.1 by the addition of 1mL of 10% Lactic acid to each 100 mL of sterile media.

Question 15

selective media

Answer 15

select for certain organisms by promoting their growth and inhibiting the growth of others

Question 16

differential media

Answer 16

used to differentiate between closely related organisms or groups of organisms

Question 17

PALCAM

Answer 17

Listeria Identification Agar Base

Question 18

MRS

Answer 18

deMan Rogosa Sharpe

Question 19

APDA

Answer 19

acidified potato dextrose agar

Question 20

BPA

Answer 20

Baird-Parker Agar