Here's a nice demonstration video by Dr. Conor O'Bryne from the Dept. of Microbiology at National University of Ireland, Galway, 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)
