KM0056 – Primary Chromogenic Coliform Agar (CCA)

//KM0056 – Primary Chromogenic Coliform Agar (CCA)

KM0056 – Primary Chromogenic Coliform Agar (CCA)

Chromogenic coliform agar (CCA) conforms to the ISO 9308-1 guidelines for the detection, enumeration and isolation of coliforms and more specifically Escherichia coli in water samples by the membrane-filtration technique.

The colonial differentiation is provided by the chromogenic substrates, Salmon-GAL and X-glucuronide. Salmon-GAL is used for the detection of ß-D-galactosidase enzymatic activity. X-glucuronide is used for the detection of ß-D-glucoronidase enzymatic activity. β-D-galactosidase, expressed by all coliforms, cleaves the Salmon-GAL substrate and producing red/pink coloured colonies. Unlike other coliforms, Escherichia coli cleaves both Salmon-GAL and X-glucuronide producing a violet/blue coloured colonies. Tryptophan is used to increase detection reliability by improving the indole reaction.

The peptones, sodium pyruvate and sorbitol support bacterial growth and simple recovery of sub-lethal thermally injured coliforms. Sodium di-hydrogen phosphate and di-sodium hydrogen phosphate phosphate buffer the medium and sodium chloride is used to achieve osmotic balance. The selectivity is attained by the addition of Tergitol® 7 as it inhibits the growth of Gram-positive bacteria.

Additional Information

Shelf Life (days)

Storage Temp (°C)

Dehydrated Medium Appearance

Prepared Medium Appearance

Dehydrated Medium Colour

Prepared Medium Colour

Dehydrated PH

Prepared PH

Product Description

OrganismRef. No.Result
Escherichia coliNCTC 12241Growth, blue/violet colonies
Escherichia coliATCC 8739Growth, blue/violet colonies
Enterobacter aerogenesNCTC 10006Growth, red/pink colonies
Citrobacter freundiiATCC 43864Growth, red/pink coloneis
Pseudomonas aeruginosaNCTC 12903Growth, colourless colonies
Enterococcus faecalisNCTC 12697Inhibited

Formula*

FORMULA*g/L
Enzymatic digest of casein1
Yeast extract2
Sodium chloride5
Sodium dihydrogen phosphate x 2H2O2.2
Disodium hydrogen phosphate2.7
Sodium pyruvate1
Sorbitol1
Tryptophan1
Tergitol®70.15
IPTG (Isopropyl-ß-D-thiogalactopyranoside)0.1
Salmon-ß-D-galactoside0.2
X-ß-glucuronide CHX salt0.1
Agar10
Total26.5g

Preparation

Suspend 26.5g of the medium in one litre of deionised / purified water. Allow the medium to soak whilst mixing for 10 minutes.

Sterilise by boiling for 100°C for 1 minute with frequent stirring to completely dissolve the medium. Cool to 45-50°C and aseptically dispense into appropriate sterile containers.