Dear SIR

prepare zobel medium. add about 20 ml of this to a petri dish. then add 1ml of your test solution. mix well by swirling. keep in a sterile environment for one day. Then you can calculate CFU/ML in a colony counter. on experience you can  determine it by simply looking at it. The dilution factor is also important,

Prof Susai Rajendran, c/o Researchgate

Prepare PCA (Plate Count Agar). Take about 15-20 ml of molten agar in sterile Petri Plate. Add 1 ml of  your test solution (serial dilution might required). Then place the plate in incubator at 37 degree celsius for 24 hours. Then calculate CFU/ml in colony counter.

Thank you sir.