I want to determine the number of bacteria in a suspension made from environmental samples. I know how to load the chamber and that I have to let the bacteria sink a bit before counting, so I can count them in the different focus plains.
I was now wondering which equation I have to use to calculate the bacteria /ml in the sample (which chamber factor do I need and how many and which quares do I need to count)?
It depends on the individual dimensions of your chamber. You calculate the volume of the individual squares and from that you know which volume of your sample you counted. I attached a file explaining the procedure in detail, is it ok for you it is written in German?
You said you let the cells sink a bit before counting. Do you then still have several focus planes? There are different chamber depths and e.g. those for blood cells are not really suitable for counting bacteria.
Thank you for the attached data sheet and your suggestions! With the samples I was counting I experienced that even after several minutes, not all bacteria were to be found in the same focus plain.
What is the depth of your chamber? Is it possible to take a smaller one? Otherwise counting might become challenging...
Generally we are using the standard Neubauer chamber (not the "improved" version). So the chamber depths should be 0.1 mm. And I figured I have to use the square in the middle to properly count the bacteria. Im just not sure which formula to use to calculate the number of bacteria / ml and how many squares (of the middle square) I have to count to get an accurate result.
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