Alkaline Peptone Water is an enrichment liquid medium which is recommended for the enrichment of clinical materials containing small numbers of Vibrio species prior to plating onto a selective medium, such as TCBS Agar.It is a modification of peptone water with an adjusted of pH 8.4.This alkaline pH of the medium allows the growth of Vibrio species while inhibiting the growth of commensal intestinal bacteria.
Principle of Alkaline Peptone Water
- Sodium chloride facilitates the growth of Vibrio species and maintains osmotic equilibrium.
- The alkalinity of this medium inhibits many commensal intestinal bacteria.
- Peptone provides nitrogen and carbon source, long chain amino acids, vitamins and other essential nutrients that enriches growth
Composition of Alkaline Peptone Water
|Ingredients||Grams / Litres|
|Sodium chloride||10.000 g|
|Distilled water||1000.0 ml|
|Final pH at temperature 25°C||8.4±0.2|
How to Prepare Alkaline Peptone Water
- Start by suspending 20.0 grams in 1000 ml distilled water.
- Then heat if necessary in order to completely dissolve the medium
- Now dispense in tubes and sterilize the medium by autoclaving at 15 lbs pressure (121°C) for 15 minutes.
Appearance of Medium after preparation
Alkaline peptone water appears light yellow coloured clear solution without any precipitate
Type of Inoculums
- Food samples
- Water samples
Procedure for Inoculation on Alkaline Peptone Water
- Inoculate the suspected specimen as soon as possible after it is received in the laboratory
- Pick the specimen using a swab or loop and Immerse the swab in Alkaline Peptone Water
- Incubate aerobically at temperature between 33-37°C for 6-8 hours.
- Now subculture on a selective growth media for vibrio species like TCBS Agar
- Incubate subculture plate aerobically at temperature 33-37°C.
- Examine plate from subculture for typical colony morphology.
Cultural Response on Alkaline peptone water
This cultural characteristics are observed after an incubation of Alkaline Peptone water at 35-37°C for 18-24 hours aerobically
For Cultural Response on TCBS Agar please refer to Thiosulfate Citrate Bile Sucrose Agar ideal for vibrio species
- Shread, P., T.J. Donovan, and J.V. Lee. 1981. Soc. Gen. Microbiol. Q. 8:184.
- Cruickshank, R. 1968. Medical Microbiology. 11th ed. Livingstone LTD, London, UK.
- Lesmana, M., E. Richie, D. Subekti, C. Simanjuntak, and S.E. Walz. 1997. J. Clin. Microbiol. 35:1856-1858.
- MacFaddin, J.F. 1985. Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria. Vol. 1. Williams & Wilkins, Baltimore, MD
- Thiosulfate Citrate Bile Sucrose Agar ideal for vibrio species