The simple answer is that they are equivalent- one MPN is equal to one CFU. Both units measure the estimated number of bacteria in a water sample. Both are recognized by a variety of scientific and regulatory bodies worldwide including the US Environmental Protection Agency (EPA) and the International Standardization Organization (ISO). The difference is in how the measurement is obtained. The use of either MPN or CFU is based on the method used for the detection of bacteria and both are valid measurements for bacteria limits.

For CFUs, bacteria grow on a solid medium, like agar.  Afterward, colonies of bacteria are counted.  For an MPN measurement, samples grown in a liquid medium, like multiple tube fermentation and Colilert.  Positive wells/tubes are then counted and an MPN conversion table is used to generate a numeric result.  

In short, laboratories and agencies worldwide use both MPN and CFU interchangeably. 

Both measurements are well-established means to estimate the number of bacteria in a sample, and both carry a 95% confidence interval.  

Hi Noemie Levy,

https://www.researchgate.net/post/Can_CFU_g_cenverted_into_MPN_g_for_bacteria_analysis

Here, you may find the adequate answer according to your question. Kindly, read the answer given by Basil Jarvis.

Regards

So fur I know there is no way to convert CFU to MPN and vice versa.

The simple answer is that they are equivalent- one MPN is equal to one CFU. Both units measure the estimated number of bacteria in a water sample. Both are recognized by a variety of scientific and regulatory bodies worldwide including the US Environmental Protection Agency (EPA) and the International Standardization Organization (ISO). The difference is in how the measurement is obtained. The use of either MPN or CFU is based on the method used for the detection of bacteria and both are valid measurements for bacteria limits.

For CFUs, bacteria grow on a solid medium, like agar.  Afterward, colonies of bacteria are counted.  For an MPN measurement, samples grown in a liquid medium, like multiple tube fermentation and Colilert.  Positive wells/tubes are then counted and an MPN conversion table is used to generate a numeric result.  

In short, laboratories and agencies worldwide use both MPN and CFU interchangeably. 

Both measurements are well-established means to estimate the number of bacteria in a sample, and both carry a 95% confidence interval.  

They are equivalent- one MPN is equal to one CFU.

The use of either MPN or CFU is based on the method used for the detection of bacteria and both are valid measurements for bacteria limits.