Question

In the context of water quality, which of the following is/are correct for the most probable number (MPN) of a water sample?

• A. The estimated organisms are gram negative.
• B. It is based on the assumption of Poisson distribution.
• C. It measures the exact number of microorganisms present in the sample.
• D. It includes the quantification of pathogenic virus.

Hint:

MPN is an estimation method used in microbiological analysis to determine the number of viable microorganisms in a water sample, particularly for pathogens.

Answer 1

The Correct Option is A, B

(A) Estimated organisms are gram negative:
The MPN method is often used to estimate the number of coliform bacteria, which are typically gram-negative organisms, in water samples. (B) Assumption of Poisson distribution:
MPN estimation is based on the Poisson distribution because it models the likelihood of rare events (like the presence of microorganisms) occurring in a sample. (C) Measures exact number of microorganisms:
The MPN method does not give an exact count of microorganisms. It provides an estimate of the number of organisms, hence it is a probabilistic method, not an exact measurement. (D) Quantification of pathogenic virus:
While the MPN method can estimate the number of microorganisms, it is also used to quantify specific pathogens, such as coliforms, which may include pathogenic viruses. Final Answer: \[ \boxed{\text{(A), (B), (D)}}. \]