ECD Medium (without Membrane Filter)

Principle And Interpretation

Field of Application: Water, food, waste water, etc. DriFilter Membrane Nutrient Pad Medium are ready to use sterile culture media in the form of a 50 mm biological inert absorbent pads impregnated with standard culture medium, then dried and sterilized in 55 mm petri plate. They eliminate the need of laborious media preparation and autoclaving procedures. The nutrient pads are to be just rewetted with sterile distilled water and are ready to use. Use of nutrient pads allows larger sample volumes to be tested at a time. Interpretation of results is directly by counting the CFUs and also quantifies the microbial load present in the sample. ECD Agar is used for detection of coliforms, especially, Escherichia coli in water, food and other samples using membrane filter technique (1). The water sample is filtered through filter membranes, which are then placed on ECD Agar and incubated overnight. Lay a drop of Kovacs Indole Reagent (R008) on the colonies. Indole positive colonies form a red zone around the colony. Indole positive colonies are enumerated as E. coli The medium has casein enzymic hydrolysate and yeast extract which provide essential nutrients especially nitrogenous sources for the coliforms. Bile salts selectively inhibit gram-positive organisms. Sodium chloride maintains the osmotic balance while phosphate salts buffer the medium.