Bacterial growth rate is measured by generation time or the time it takes for a bacterial cell to divide into two. Generation time differs for different types of bacteria. For most bacteria like E. coli, it takes about 20 minutes under optimal conditions.A bacterial growth curve depicts the population change of bacteria over time, while generation time measures the time it takes for a bacterial population to double.Lag phase – bacteria adapt to the environmentLog (Exponential) phase – rapid cell divisionStationary phase – growth slows due to limited nutrientsDeath phase – cells die faster than they reproduce