Abstract:Heredity and variations are most essential problems in biology. Estimating the mutation rates will be a great help for well understanding the difference among the different genes, different biological species, and under different growth environments. Bacteria are the best mode for estimating mutation rates due to their fast growth rates and their huge population sizes. Mutation rate (μ) is defined as the probability of mutation in each bacterial cell and each bacterial generation, usually expressed as Here, is the number of mutations, and is the number of generations. In some famous microbiology and genetics textbooks and monographs, ln2, as the synchrony coefficient for non-synchronous bacterial population, was introduced into the mutation rates calculation formulae, but in others not. So, how to calculate the mutation rates in non-synchronous bacterial population? Just introduce coefficient ln2 is enough? In this essay, by analyzing the mathematical characteristics of exponential growth in bacterial population, both synchronous and non-synchronous, the biological meaning of ln2 was been well expressed, i.e., It means, in non-synchronous population, the ratio of generation time (TG) to doubling time (TD) is ln2. However, in ideal synchronous population, the generation time (TG) is equal to the doubling time (TD). Because in non-synchronous population, the number of generations was usually estimated by the experimental data, these data had been already included the non-synchrony factor of the experimental population, it was no need to introduce ln2 as synchrony coefficient into mutation rates calculating formulae. If the number of generations was not estimated by experimental data, it was need to carefully calculate the value of generations based on the given data, rather than just introduced ln2 as synchrony coefficient into mutation rate calculating formulae.
