Microbiology Dilution series demonstration

Demonstration video showing how to perform a serial dilution on a liquid food sample (in this case raw unpasteurised milk). The raw milk sample is diluted down to 1/1000 in a sterile diluent (Ringers solution). 1ml samples of each dilution are then used to prepare 2 sets of pour plates. A 0.1ml sample from the 1/10 and the 1/100 dilutions is used to generate spread plates. For this method you require the following: Sterile 1ml pipettes A pipette pump Sterile agar plates (for pour plates) Poured agar plates (for spread plates) A spreader (glass or metal) A dish of lab ethanol Bunsen burner Glass Universal tubes with 9 ml of sterile diluent Molten agar medium (20ml plate count agar per Universal tube - kept at 48C until ready to pour)