Most Probable Number (MPN) Test Quiz

What does the MPN test estimate?

• Concentration of viable microorganisms

• Presence of toxins in water

• pH level of the water

• Temperature of the water sample

Which group of bacteria is commonly used as an indicator of fecal contamination in water?

• Staphylococcus

• Fecal coliforms

• Salmonella

• E. coli

What is the first step in the MPN test procedure?

• Confirmatory test

• Completed test

• Presumptive test

• Preparation of the medium

What medium is typically used in the MPN test?

• Nutrient agar

• Lactose broth

• Mannitol salt agar

• Blood agar

What indicates a positive reaction in the presumptive test?

• Only color change

• Color change and gas production

• Only gas production

• No change in color or gas

What is the incubation temperature for the MPN test?

• 44.5°C

• 25°C

• 30°C

• 37°C

What is a disadvantage of the MPN test?

• Easy interpretation

• High probability of false positives

• Requires less equipment

• Quick results

What does the confirmatory test check for?

• Presence of coliforms

• Presence of viruses

• Presence of protozoa

• Presence of fungi

What is the purpose of the completed test?

• To measure pH levels

• To sterilize the equipment

• To prepare the medium

• To confirm the presence of coliforms

What is the main advantage of the MPN test?

• It can analyze highly turbid samples

• It is less expensive

• It is very quick

• It requires no special equipment