Enumerating Microorganisms

Enumerating microbes in a sample is a useful technique. Here we discuss two methods to estimate the number of microbes in a sample. One quick method is to measure turbidity in which the density of cells is measured with a spectrophotometer. A viable count, a second method, requires the dilution of a sample, the dilution is spread on an agar plate with the nutrients for the microbe, and after growth, the scientist counts the colonies formed. Each colony represents growth from one microbe.