If i need a plate a sample concentration of 1:10000000000(1:10-10), how can i shorten the procedure in the lab instead of having to do all the steps?
Hello Mr. Jactone,
That is easy, if your initial stock is estimated to be 1,000,000,000 CFUs per ml and you need you dilute it to let us say estimated 250 CFUs per ml that can easily be counted....
first find the total/overall dilution factor
which is calculated as final concentration that is needed divided by the initial concentration in our example it will be;
250/1,000,000,000 = 0.00000025
here you can make only three or even three dilutions to get the estimated 250cfu/ml,.
Find the possible combination (depending on how many dilutions you need) that will give you the the total dilution ( if you need to dilute only twice, find two values, three, find three values) as in my example
for instance i want to do three dilutions only to get estimated 250CFUs,
1 ml of stock can be added to 99ml of diluent to make (1/100) then 1ml of the result to 499ml of diluent (1/500) the 1ml to another 499ml of diluent (1/500).
this will give the same total dilution
i.e 1/100 x 1/500 x 1/500 = 0.00000025
therefore with well calculation you can even make less dilutions to achieve the required countable CFU.
I hope it will be of help to you.
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