Temperature And Humidity; Determining Results - Cantium Scientific MicroBio MB1 Operating Manual

Temperature and Humidity

It is useful to take a note of these values at the time of each sample.
Temperature and humidity are important factors in the likely concentration
and viability of airborne micro-organisms.
survival rates are 35 to 65 times higher at 80%RH compared to 40%RH.

Determining Results

Once the sample has been taken, the contact plate or petri dish should be
removed and sealed with its protective lid. A note should be made on the lid
regarding time, location and volume sampled.
The plate should then be incubated for a period of time and temperature
dependant on the requirements of the media.
Once incubated, the colony growths are then counted, either manually or
using an automatic colony counter.
sampling method and the chance more than one colony impinged at one
point on the dish, a count correction needs to be performed.
The tables in Appendix A and Appendix B gives the corresponding
corrected value for the 220 hole and 400 hole sampling heads respectively.
Alternatively, the following equation can be used to determine a corrected
count.
Where n is the number of holes on the sampling head, n
h
counted colonies and n
Due to the statistical nature of the
⎛
⎜
1.075
= n
⎜
n
c f
⎜
1.052 −
⎝
is the corrected count.
c
15
For example, some bacteria
0.483
⎞
⎟
⎟
n
⎟
f
⎠
n
h
is the number of
f