It is requested to please suggest that i have a standard method that gives answer in MPN/g and the requirement is that the result of Food microbiology must be reported in CFU/g. Kindly mention any personal work or research.
thankyou
MPN is most probable number between 25-300 count of microbes. if the MPN/g less than 25 means zero CFU/g
There is no way to convert CFU to MPN and vice versa. CFU's are the Colony Forming Units in a given sample volume as in, these ARE the colony forming units in 100mLs of a sample. CFU's are definitive. MPN's are the Most Probable Number of cfu's in a given sample volume as in, there are PROBABLY this many cfu's in 100 mLs of a sample. MPN is an estimate of probability. (answered by Wiki)
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.
@Dear Prof. Sami,
I appreciate your quite elaborate answer and agree too on the same except the fact that you have probably assumed that CFU/g and MPN are estimates of bacteriological quality parameters of water alone.
Further it is also true that for both water, milk and few other dairy products this is true and valid as this generally applies to fluid products as listed above.
However, when it comes to variety of solid food stuffs it is CFU/g that has been prescribed by regulatory authorities world over rather than MPN protocol.
Further MPN cannot directly be equated to CFU/g or CFU/ml though one may say that both are somewhat equivalent measures of bacteriological quality parameters and I have already dwelt in more details earlier on the same thread to highlight the difference between two.
Regards,
@Dear Prof. Sami,
There is one correction* in the sense that I had posted my response earlier but not on this thread. But I distinctly remember a similar question came up for discussion on RG platform some time back.
Regards,
MPN is a serial dilution tests that is used to estimate the concentration of viable organism in a sample. This method is useful with samples that contain particulate material that interferes with plate count enumeration methods. Both the MPN and plating method (CFU) are equivalent.
CFU = bacteria grow on a solid medium (plating method) and the colonies of bacteria are counted.
MPN = samples grown in a liquid medium (MPN) and the positive tubes are then counted and an MPN conversion table is used to generate a numeric result.
Both measurements are well-established means to estimate the number of bacteria in a sample, and both carry a 95% confidence interval.
Dear Shelly Saima,
I appreciate you for the most tricky technical question that has been posted on RG so far and we all are awaiting for the satisfactory answer yet.
If I am not wrong we all know the protocols for estimation of MPN/g or ml and CFU/g.
Both methodologies are based on certain presumptions before the statistical analysis is applied to arrive at the conclusion/correct answer.
But I am not very sure whether the interconversion of these two units is really possible.
To state that both these terms are equivalent is definitely a daring statement.
Despite the fact that Mathematics and Statistics are considered as mother of all sciences and it is true indeed still there is a scope to believe that there could be some complications of statistical methods which are rather beyond comprehension.
For simplicity I will put it this way.
There is no point in saying that "the mean human body temperature is 37 degree Celcius and everything is fine when in an imaginary situation if you try to visualize following situation":
The half of the body is kept in a deep freeze at minus 200 degree Celcius and the other half is in the muffle furnace at 237 degree Celsius.
My advice will be not to oversimplify the things if it is not required do do so.
Regards,
- Badges
- Science method