Fig 2. Analysis of self-replicator model of bacterial growth.

A: Phase-plane analysis of the self-replicator model of Eqs 3 and 4. The nullclines for p and r are shown as solid and dashed curves, respectively. Parameter values are e_M = 3.6 h^-1, k_R = 3.6 h^-1, K_R = 1 g L^-1, β = 0.003 L g^-1, α = 0.45. B: Dependence of the growth rate at steady state μ* on the resource allocation parameter α, for two different environmental conditions (solid line, e_M = 4.76 h^-1; dashed line, e_M = 1.57 h^-1, other parameter values are k_R = 2.23 h^-1, K_R = 1 g L^-1, and β = 0.003 L g^-1). The maximal growth rate is attained for a unique α, called ${\alpha }_{opt}^{*}$.