103 Lecture Notes - Lecture 2: Bacterial Growth, Logarithmic Scale, Microbiological Culture
Document Summary
When a broth culture is inoculated with a small bacterial inoculum, the population size of the bacteria increases showing a classical pattern. When plotted on a graph, a distinct curve is obtained referred to as the bacterial growth curve. A population growth curve for any particular species of bacterium may be determined by growing a pure culture of the organism in a liquid medium at a constant temperature. Samples of the culture are collected at fixed intervals (e. g. , every 30 minutes), and the number of viable organisms in each sample is determined. The data are then plotted on logarithmic graph paper. The logarithm of the number of bacteria per milliliter of medium is plotted against time. The bacterial growth curve shows the following four distinct phases: lag phase: After a liquid culture broth is inoculated, the multiplication of bacteria does not start immediately. The time between inoculation and beginning of multiplication is known as lag phase.
