Soybean Casein Digest Broth: Introduction, Composition, Principle, Prepar

Soybean Casein Digest Broth: Introduction, Composition, Principle, Preparation, Test Procedure and Uses

Soybean Casein Digest Broth

Soybean Casein Digest Broth is a general-purpose medium and uses for the cultivation of a wide variety of microorganisms. It is also used in sterility testing of molds and lower bacteria in accordance with United States Pharmacopoeia (USP).

Composition of Soybean Casein Digest Broth

Ingredients Gms / 100 ml

Pancreatic digest of casein: 1.7

Papaic digest of soybean: 0.3

Sodium chloride (NaCl): 0. 5

Dibasic potassium phosphate (K₂HPO_4): 0.25

Glucose monohydrate: 0.25

pH after sterilization (at 25°C): 7.3±0.2

Principle of Soybean Casein Digest Broth

Papaic digest of soybean and pancreatic digest of casein supply amino acids and long-chain peptides for the growth of organisms. Soybean natural sugars promote the growth of fastidious microorganisms. Glucose is the fermentable source of carbon whereas dibasic potassium phosphate serves as the buffer in the medium. Sodium chloride maintains the osmotic balance of the medium.

Preparation of Soybean Casein Digest Broth

Suspend 2.97 grams in 100 ml purified/distilled or deionized water.
Heat to boiling to dissolve the medium completely.
Desired volumes and containers ( vial or tube or bottle) can be taken according to the nature of the testing purpose.
Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.
After autoclaving, leave for cooling to room temperature.
Store the plates in a refrigerator at 2-8°C.

Storage and Shelf life of Soybean Casein Digest Broth

Store at 2-8ºC and away from direct light.
Media should not be used if there are any signs of deterioration or contamination.
The product is light and temperature-sensitive; protects from light, excessive heat, moisture, and freezing.

Test Requirements

Test specimens ( samples or growth of test organisms)
Inoculating loop
Bunsen burner
Incubator
Control strains (Escherichia coli ATCC 25922, Staphylococcus aureus
ATCC 25923, Candida albicans ATCC 10231, Aspergillus brasiliensis ATCC 16404)

Test procedure ( specimen/organism inoculation)

Allow the medium to warm at 37°C or to room temperature.
Inoculate the specimen as soon as possible after collection.
Incubate aerobically at 35-37ºC for 18-24 hours.
Examine for growth.

Result Interpretation

Escherichia coli ATCC 25922: good-luxuriant
Staphylococcus aureus ATCC 25923): good-luxuriant
Candida albicans ATCC 10231: good-luxuriant
Aspergillus brasiliensis ATCC 16404 : good-luxuriant
To say growth nil ( negative): Subculture into solid medium and after incubation check the growth that is without colonies.

Sterility Testing- Growth promotion+Validation

Staphylococcus aureus ATCC 25923: luxuriant growth @ 20 -25 °C within 3 days
Escherichia coli ATCC 25922: luxuriant growth @ 20 -25 °C within 3 days
Salmonella Typhimurium ATCC 14028: luxuriant growth @ 20 -25 °C within 3 days
Streptococcus pneumoniae ATCC 6305: luxuriant growth @ 20 -25 °C within 3 days
Candida albicans ATCC 10231: luxuriant growth @ 20 -25 °C within 3 days
Aspergillus brasiliensis ATCC 16404: luxuriant growth @ 20 -25 °C within 3 days

Uses of Soybean Casein Digest Broth

Soybean Casein Digest Broth is a general-purpose medium and is also applicable for the cultivation of a wide variety of microorganisms. Therefore, it also applies in clinical species to find out etiological agents.
It is the USP-recommended sterility testing medium.
It is applicable for antimicrobial sensitivity testing (AST) by the tube dilution method.
It is also useful in diagnostic research microbiology.
It is useful as a diluent and suspending medium for the preparation of samples or test strains.

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