Which technique allows enumeration of living bacteria in a liquid culture?
a. Assay of cell mass by nephelometry
b. Estimation of DNA concentration
c. Microscopic count
d. Miles-Misra plate count
e. Weighing of total cell mass.
The correct answer is (d) Miles-Misra plate count.
The Miles-Misra plate count, also known as the viable count or colony-forming unit (CFU) assay, is a technique used to enumerate living bacteria in a liquid culture. It involves:
1. Serially diluting the culture
2. Plating the dilutions on a solid medium (agar)
3. Incubating the plates to allow colonies to form
4. Counting the number of colonies, which represents the number of viable bacteria in the original culture