preparation of culture media we culturing microorganisms to see and sudy it . in the culture media there is three type of media solid sime solid and liquid . How to make culture media : 1. Weigh 6.5 grams of the sterile nutrient broth and transfer into the clean conical flask. 2. Add 500 ml of distilled water into the measuring cylinder and transfer into the conical flask . 3. Put the conical flask with the media solution from step 2 into an autoclave basket. 4. Allow the autoclave to cool down. 5. Put the petri dishes into a hot air oven at 80ºC for one hour to sterilize them. 6. Remove the conical flask containing the now sterile media from the autoclave. 7. Label the petri dishes and store in a refrigerator for later use. Make dilution for water sample . we use dilution to reduce the amount of bactiria in the water . to make dilution for water sample first prepare 5 test tube add 9ml dilution liquid and add for first tube 2ml from bacteria after that take with pipette 1ml and add it to second tube repeat that to 5th tube. Like that we reduce amount of bacteria . Characteristics of Bactria colony morphology . characteristics used to accurately and consistently describe the morphology of bacterial colony. We can describe bacterial colony in 6 classification : Size Shape Color Texture Height and Edge. Antibiotic . Antibiotics they inhibits the growth and replication of a bacteria and kill it . Antibiotics sensitivity test: 1.Select a pure culture plate of one of the organisms to be tested. 2.Aseptically emulsify a colony from the plate in the sterile saline solution. Mix it thoroughly to ensure that no solid material from the colony is visible in the saline solution. 3.Repeat until the turbidity of the saline solution visually match that of the standard turbidity. 4.Take a sterile swab and dip it into the broth culture of organism. 5.Gently squeeze the swab against the inside of the tube in order to remove excess fluid in the swab. 6.Take a sterile Mueller-Hinton agar (MHA) plate or a nutrient agar (NA) plate. 7.Use the swab with the test organism to streak a MHA plate or a NA plate for a lawn of growth. 8.After the streaking is complete, allow the plate to dry for 5 minutes. 9.Antibiotic discs can be placed on the surface of the agar using sterilized forceps. 10. Gently press the discs onto the surface of the agar using flame sterilized forceps or inoculation loop. 11. Carefully invert the inoculated plates and incubate for 24 hours at 37° C. 12. After that you can see the different in zone sensitive Gram staining Gram stain is a method of staining used to distinguish and classify bacterial species into two large groups grampositive and gram-negative. We use gram staining to see bacteria in the microscope . First Preparing a smear for staining and Flame your inoculating loop drop water on clean slide spared it into the slide let the smear dry after the heat it , flood the smear with stain and let it 1 minuet after that you can see it under microscope .