1 Standard Plate-count Bacteria
1.1 Plate counting method
1.1.1 Scope
This standard specifies the plate counting method for determination of standard plate-count bacteria in drinking water and its source water.
This method is applicable to the determination of standard plate-count bacteria in drinking water and its source water.
1.1.2 Term and definition
For the purposes of this standard, the following term and definition apply.
1.1.2.1
Standard plate-count bacteria
The total number of bacterial colonies contained in 1mL water sample obtained through culture of water sample on nutrient agar under aerobic conditions at 37℃for 48h.
1.1.3 Culture medium and reagent
1.1.3.1 Nutrient agar
1.1.3.1.1 Constituents:
A Peptone 10g
B Beef extract 3g
C Sodium chloride 5g
D Agar 10g~20g
E Distilled water 1000mL
1.1.3.1.2 Preparation method: mix the above constituents, heat them until they are dissolved, adjust pH to 7.4~7.6, and fill them into glass containers (filter first where agar containing much impurity is adopted); sterilize at 103.43kPa (121℃, 15lb) for 20min, and store in cool dark place for standby.
