Total Viable Count - This involves counting the colonies produced by viable cells under favourable growth conditions. In pour-plate method, an aliquot of suitably diluted sample is mixed with nutrient agar at a temperature where it is liquid. Then the mixture is poured into petridishes and allowed to set.
Alternatively an aliquot of the sample is spread over the agar surface of a Petridis using a sterile spreader. Membrane filters can also be used to determine the bacterial numbers. In this method cells are filtered onto membrane filter which is then placed over nutrient agar surface.
