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Spread plate volume - (Oct/22/2013 )

Recently started working a new job and was brought in to help with microbiology.  Current protocol calls for spread plating 1mL of sample onto agar and immediately inverting and placing in incubator.  In 10 years, I have never seen this much volume used for spread plating nor have I seen plates inverted without allowing the sample to dry first.  Has anyone else ever used a method similar to this?  I have always used somewhere between 100-300uL for spread plating and always allowed the liquid to dry.  Thanks for any insight.


Nope, I've never spread that much volume either.  I've also never not allowed the liquid to absorb into the plate for at least a few minutes before inverting.  The method sounds suspect - did they provide a rationale?


i'd definitely question the protocol.  Simple inverting the pate after inoculation should be enough to show the method to be flawed.

-Phil Geis-

Nope. never. Too large volume of sample will causing the difficulties of agar to absorb. Secondly, immediate invert is not a good idea, sample will drop down from the edge of plate and could not provide the reliable result.  


The most I have seen spread plates is 0.5ml. however you can you use up to 2 ml in pour plates. I would advise using pour plates for volumes greater than a 0.5ml