Potato Dextrose Broth

Intended Use

Potato Dextrose Broth (DM216) is used for the cultivation of fungi.

Product Summary and Explanation

Potato Dextrose Broth is a general purpose broth for yeasts and molds. The low pH of this medium inhibits bacterial growth. Potato Dextrose Broth is the same formula as Potato Dextrose Agar, but agar has been omitted. Potato Dextrose Broth is recommended by APHA ⁽¹⁾ and F.D.A. ⁽²⁾ for plate counts of yeasts and moulds in the examination of foods and dairy products ⁽³⁾. Potato Dextrose Broth is also used for stimulating sporulation, for maintaining stock cultures of certain dermatophytes and for differentiation of typical varieties of dermatophytes on the basis of pigment production.⁽⁴⁾

Principles of the Procedure

Potato Dextrose Broth is composed of Potato Infusion Solids and Dextrose that encourage luxuriant fungal growth. Adjusting the pH of the medium by tartaric acid to 3.5, inhibits the bacterial growth. Heating the medium after acidification should be avoided.

Formula / Liter

Ingredients	: Gms / Litre
Potato Infusion Solids	: 200.0
Dextrose	: 20.0
Final pH: 5.1 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications

Precautions

1. For Laboratory Use only.
2. IRRITANT. Irritating to eyes, respiratory system, and skin.

Directions

1. Suspend 24 g of the medium in 1000 ml of distilled water.
2. Heat to completely dissolve the medium.
3. Autoclave at 121°C, 15 lbs pressure, for 15 minutes. Mix well before dispensing.
4. In specific work, when pH 3.5 is required, acidify the medium with sterile 10% tartaric acid.
5. The amount of acid required for 100 ml. of sterile, cooled medium is approximately 1ml.
6. Do not heat the medium after addition of the acid.

Quality Control Specifications

Dehydrated Appearance	: Off-white to yellow, homogeneous, free flowing powder
Solution	: 2.4% Solution in Distilled or deionized water is soluble on boiling, very pale yellow colored, and clear.
Prepared Medium	: Pale Yellow colored clear to slightly hazy solution.
Reaction of 2.4% Solution	: pH 5.1 + 0.2 at 25°C
Gel Strength	: Not Applicable

Expected Cultural Response: Cultural response in Potato Dextrose Broth at 25-35°C after 2 – 7 days of incubation.

Sr. No.	Organisms	Results to be achieved
Sr. No.	Organisms	Inoculum(CFU)	Growth	Ascospore formation
1.	Candida albicans ATCC 10231	50-100	luxuriant	Negative
2.	Aspergillus brasiliensis ATCC 16404	50-100	luxuriant	Negative
3.	Saccharomyces cerevisiae ATCC 9763	50-100	luxuriant	Positive

The organisms listed are the minimum that should be used for quality control testing.

Test Procedure

Refer to appropriate references for a complete discussion on the isolation and identification of yeast and molds.

Results

Growth is indicated by turbidity.

Storage

Store the sealed bottle containing the dehydrated medium at 10 – 30°C. Once opened and recapped, place contain er in a low humidity environment at the same storage temperature. Protect from moisture and light.

Expiration

Refer to the expiration date stamped on the container. The dehydrated medium should be discarded if not free flowing, or if the appearance has changed from the original color. Expiry applies to medium in its in tact container when stored as directed.