 Curd is made by bacterial fermentation of milk. In this process, lactose present in the milk is converted into the lactic acid with the help of probiotic microorganisms. The species that are involved in the fermentation depends on temperature, humidity of environment for growth. The most important probiotic microorganisms that are involved in bacterial fermentation include Lactococcus lactus, Streptococcus thermophilus, Lactobacillus, Dull Broke, Sub-species thermophilus, etc. For the preparation of curd sample, calling procedure is used. Regents required. Yogurt samples diluted in 1 to 10 ratio in sterile normal saline. 6 test tubes containing diluent which may be distilled water or 0.9% saline solution. Tips. Micro-piped for the preparation of cereal dilutions. MRS media, sterile petri plates and inoculating lube. Collect sample and dilute in 1 to 10 ratio in normal saline solution. Now, pick 1 ml yogurt solution and add into first test tube containing 9 ml distilled water. Mix it properly. By using this previously mentioned procedure, make 6 dilutions from the first dilution. For completion of cereal dilutions, use 10 to minus 6 dilution for inoculation. Now, pour the agar into the petri plate. Helpfully distribute the sample throughout the plate and place it to dry. This is already prepared plate. Now, we take 10 to minus 6 dilution for inoculation to use straight plate method. Claim the inoculating lube to red hot then allow it to cool for 1 to 2 minutes. After cooling, dip the lube in 10 to minus 6 dilution and carefully stick plate in a zig-zag manner. For the completion of inoculation, again, claim the inoculating lube. Now, place the inoculated plate in an incubator for overnight for 48 hours. After incubation, we will observe lactobacillus species and count colonies with the help of colony counter.