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)

Category:

Education

Tags:

• Microbiology
• practical
• demonstration
• Conor
• o'Byrne
• Sinead
• Heavin
• food
• milk

[rezaeijavan]

WE did it in our first year , and in our first week... Is that Normal?

[SuperMesho11]

and the most important is ware gloves before strat

thank's

[Deadcattz]

Lab safety! Your hair will catch on fire

[HaoSci]

Sorry to ask the irrelevant question, but what background music is played? Which ethnics is it associated with?

Thanks very much for the demonstration.

[katie89100]

I would have used a Gilson, that pipette was dripping.

[katie89100]

@alllitangio It's just milk, more protection may be needed once the bacteria have grown.

[Vebzther]

Pls answer me guys I really need help. I am asked to perform total plate count/aerobic plate count on a pasteurized fruit juice. I need to prove that the product is safe to drink. My teacher told me to make 0, -1, and -2 dilution. If I want to prove that my product is safe thru microbiological reasons does that mean that all my plates should have 0 count? Is it fine to have count at the range of 30-300? Or does 30-300 count mean that my juice product is not safe to consume? TY!

[jasminestewart08]

@rezaeijavan no,i dont think so. we did this on our 2nd year.

[1988iCandy]

thanks for the demostration.