Viable plate count procedure

When the CO2 treatment was finished, residual viable micro-organisms were counted according to plate standard procedures (for solid media and conditions see Table 9.10-1). The cultures were suspended in PBS buffer and diluted to reach about 107 colony-forming units, CFU/ml, for bacteria and 105 CFU/ml for yeast. 

The agar [9002-18-0] plate method consists of adding a known quantity of sample, usually 1.0 or 0.1 mL, depending on the concentration of bacteria, to a sterile petti plate and then mixing the sample with a sterile nutrient medium. After the agar medium solidifies, the petti plate is incubated at 32°C for 48 hours after which the bacterial colonies are counted and the number expressed ia terms of a 1 mL or 1 g sample. This procedure measures the number of viable organisms present and able to grow under test conditions, ie, 32°C. 

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