EC Broth, 500 g (C08-0442-882)

EC Medium is used for detection of coliforms during bacteriological examination of water, milk and foods. It was originally described by Hajna and Perry (1). This medium was later used by Fishbein and Surkiewicz to carry out Escherichia coli confirmatory tests (2). It is also used in MPN methods (3) and is often used for confirmation of coliforms. The procedure employing EC Medium provides information regarding the source of the coliform group (fecal or non-fecal) when used as a confirmatory test (4). EC Broth should not be used for the direct isolation of coliforms since prior enrichment in a presumptive medium for optimal recovery of faecal coliforms is required. Tryptone provides nitrogenous and carbonaceous compounds, long chain amino acids and other essential growth nutrients. Lactose is the fermentable sugar. Bile salts mixture inhibit gram-positive bacteria especially bacilli and faecal Streptococci. Phosphates control the pH during fermentation of lactose. Gas production in a fermentation tube within 24 hour or less is a presumptive evidence of the presence of coliform bacteria. This medium can be used at 37deg C for the detection of coliform organisms or at 44.5deg C for the isolation of Escherichia coli from water and shellfish) or 45.5deg C for foods. When using sample more than 10 ml, the medium must be reconstituted at a concentration equivalent to that specified on the directions, once the sample is added, the working procedure is as follows: Transfer a loopful of culture from all the tubes of Lauryl Sulphate Broth (M080) showing gas formation within 24 hours and from all the tubes showing bacterial growth within 48 hours to EC Broth tubes. Within 30 minutes from the inoculum, place the tubes in a water bath and incubate at 44deg C for 24 hours. Consider the growth showing gas production as positive. Application: For the Selective Enumeration of Presumptive Escherichia Coli by Mpn Technique from Water Samples and from Clinical Samples Appearance: Cream to yellow homogeneous free flowing powder Color and Clarity of prepared medium: Yellow colored, clear solution without any precipitate Cultural Response: Cultural characteristics observed after an incubation at 44.5 deg C ± 0.2 for 24 hours