good day dears :
I ask if we exposed petri dish for 30 minutes and the result was 15 colonies how we can calculate cfu/m3 kindly mention to references .
Afaik, settle plate data is currently more often used to calculate cfu/area/time.
Impaction techniques are commonly used if cfu/m3 values are required.
Nonetheless, a value for cfu/cm3 for yr settle plate data can be estimated via Omeliansky's formula as shown in this post 18 –
(also see Post6/method2, Post17)
A reference illustrating use of the Omeliansky formula is attached.
Sedimentation with the Omeliansky formula,2012.pdf 44.61KB
Edited by Charles.C, 03 February 2017 - 07:21 AM.
combined, see post 7