Question

What is MPN?

A. It is the same technique as dilution plating/plate counting, minus taking a 1mL sample from the tube and placing it on a plate. Instead, we are now counting growth in 10mL (there is 10x more of the original culture in the tubes than there would be on the plates).

B. MPN is a method used for determining the concentration of microorganisms in a sample by counting the number of positive growths in a series of multiple tubes containing different dilutions of the sample.

C. MPN stands for "Most Probable Number" and involves statistical estimation to determine the concentration of microorganisms in a sample based on the presence or absence of growth in a series of tubes with varying dilutions.

D. MPN involves isolating microorganisms by serial dilution and then transferring these dilutions into tubes or wells to observe growth patterns and estimate the probable number of viable microorganisms present in the original sample.

Answer 1

The Most Probable Number (MPN) is a statistical technique for estimating viable microorganisms' concentrations in dilute samples by observing growth in a series of dilutions and linking this to a probable number of organisms in the original sample, frequently used in water and food testing.

Step-by-step explanation:

Most Probable Number (MPN) is a method used by microbiologists to estimate the number of viable microorganisms in a sample. This technique is particularly useful for specimens with low bacterial counts that are difficult to detect by traditional plate count methods, such as in water or food samples.

In the MPN method, a sample undergoes serial dilution, and aliquots are added to growth media in multiple tubes or wells. Observing which tubes show positive growth, often indicated by turbidity or a color change due to metabolic activity, allows estimation of the microorganisms' concentration in the original sample using statistical techniques

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The MPN method is especially beneficial when samples are too dilute for plate counting or when direct cell counting methods like the viable plate count are inappropriate. Common applications include testing for the presence of coliforms in drinking water or determining the bacterial count in food samples.

This method emphasizes the importance of dilution and growth detection to arrive at the most probable number of live microorganisms present.