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The count represents the number of colony forming units (cfu) per g (or per ml) of the sample. A TVC is achieved by plating serial tenfold dilutions of the sample until between 30 and 300 colonies can be counted on a single plate. The reported count is the number of colonies counted multiplied by the dilution used for the counted plate
The Miles and Misra Method (or surface viable count) is a technique used in Microbiology to determine the number of colony forming units in a bacterial suspension or homogenate. The technique was first described in 1938 by Miles, Misra and Irwin who at the time were working at the LSHTM. [1] The Miles and Misra method has been shown to be ...
The pour plate technique is the typical technique used to prepare plate count agars. Here, the inoculum is added to the molten agar before pouring the plate. The molten agar is cooled to about 45 degrees Celsius and is poured using a sterile method into a petri dish containing a specific diluted sample.
Spiral plating is used extensively for microbiological testing of food, milk and milk products and cosmetics. It is an approved method by the FDA. [2] The advantage of spiral plating is less plates used versus plating manually because different concentrations are present on each plate.
The spread plate method wherein the sample (in a small volume) is spread across the surface of a nutrient agar plate and allowed to dry before incubation for counting. [ 11 ] The membrane filter method wherein the sample is filtered through a membrane filter, then the filter placed on the surface of a nutrient agar plate.
The plate count method relies on bacteria growing a colony on a nutrient medium so that the colony becomes visible to the naked eye and the number of colonies on a plate can be counted. To be effective, the dilution of the original sample must be arranged so that on average between 30 and 300 colonies of the target bacterium are grown.
In the Plate Count Method, the sample of drug product to be tested and Soybean-Casein Digest Broth is poured into a Petri dish. [4] The Petri dish is then incubated. The most probable number method (MPN) can also be performed for products considered to have a low bioburden [ clarification needed ] .
After allowing to dry, it is colored and performs counting. For this, the average of existing cells is performed in the field of the microscope, dividing total somatic cells from microscopic factor (MF) which corresponds to the number of fields in one inch, i.e. 100 mm, obtaining in this way the number of somatic cells per milliliter of milk .