What is the population of coliforms and generic E.coli in the following sample?

Question

What is the population of coliforms and generic E.coli in the following sample? you plated 150ul per plate (duplicate plates) and all dilutions were made on 9 ml 0.1% peptone water tubes. Initial weight of the sample was 10g and you added 90ml of 0.1% peoptone water and you homegenized the sample for 1 minute before you made the dilutions listed below

plated dilutions           Coliforms counts                        generic E. coli counts

-4                                        325 and 288                                    0

-3                                             TNTC(too numerous to count)       0 and 1

-2                                               TNTC(too numerous to count)         22 and 26

Explanation / Answer

Here, the initial Wight of the sample is 10 grams and it is added to 90 ml of 0.1% peptone. Thus, each ml contains 0.1 grams of the sample. So, 0.1 gram (1ml) sample added to the 9 ml of 0.1% peptone at 10-1 dilution. So, now 1 ml contains 0.01 grams of sample.  

Thus, here we cannot count the population of coliforms and generic E.coli.

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