Answer to Question #34980 in Microbiology for shaily

Question

tell me calculation of Colony forming unit for product. i prepared serial dilution 10 ml sample in 90ml i.e1:10 ratio, transfer 1ml into 9ml saline i.e 1:100, i got 4 colony in 1:10, 2 colony in 1:100 dilution

Answer 1

You should perform the calculations for the most diluted solution. Thus, you should take into consideration only the second dilution. You should multiply 2 colonies obtained for the level of dilution - 10^2.
2*100^2=200 colonies per volume you inoculated.
Divide 200 by the volume you used to make inoculation and you will get the number of bacterial cells in 1 ml.

You can multiply the number of bacteria in 1 ml and thus, you will get the total number of bacteria in your product.