Modes of Population Changeovers in Continuous Culture of Bacterial and Viral Mutants Spectrum

Dynamics of a continuous culture of bacterial and viral mutants population produced by a random mutagenesis was analyzed mathematically and numerically. The selection coefficient distributions among initial mutants population were classified into three categories by the shape of logarithm of the distribution function; (i) concave, (ii) linear and (iii) convex. Time courses in the three categories were quite different and insensitive to growth models and method of culture. The population changeover took place only once in the concave case. Multiple sequential population changeovers occurred in the convex case. The "isopopulation" time point emerged in the linear case. Selection coefficient distribution among randomly mutagenized population can be calculated from the local fitness landscape around the base sequence of the wild-type. An ideal Fujiyama-type landscape provided a slightly convex distribution of random mutants and led to sequential population changeovers in continuous culture.