Question

Check the temperature of the water bath containing the nutrient agar. Test the temperature of the outside of the agar container with your hand. It should be warm, but not too hot for your bare hand. Why? _________________________ Pour the melted nutrient agar into one of the dishes (to about one-third full) (FIGURE 54.3b). Cover the plate, and swirl it gently (FIGURE 54.3c) to distribute the milk sample evenly through the agar. Continue until all the plates are poured. When each plate has solidified, seal with tape, invert it, and incubate all plates at 35 degree C for 24 to 48 hours.

Answer 1

In the HPC or SPC i.e.abbrevated as Heterotrophic plate count or standard plate count, the same pippette is used because of same sample dilution is taken we need to obtain all the bacterial population in the dilution sample same pippette gives better removal sticked bacteria to the pippette walls also.

2) we need to check the temperature of the molten agar medium before the palting the sample innoculant as we know hetertrophic efficiency depends on the sample innoculation, type of the media used and temperature administered for the growth of the bacteria, the optimum temperature ie..35C is used for the efficient temperature for growth and withstand viability of the bacterial forms which present in the diluted samples..

After plating these are covered and incubated and colonies are developed and CFU palting efficiency is calculated after necessary incubation time.

:-)