REPRODUCTION RATE, FEEDING PROCESS, AND LIEBIG LIMITATIONS IN CELL POPULATIONS—Ⅱ

摘要

A biological system consisting of a population of cells suspended in a liquid substrate is considered. The general problem addressed in the paper is the derivation of the kinetic pattern of population growth as a statistical effect of a very large number of elementary interactions between a single cell and the molecules of nutrient in substrate. Solution of the problem is obtained in the form of equation expressing the population growth rate c as a function of substrate concentration, C_s. The analytical expression derived is applied to a real bacterial population (Escherichi coli) and kinetic patterns are theoretically computed. The major findings, expressed roughly, without nuances, are: (ⅰ) the concentration of nutrient at the cell membrane, C_c, can only be equal to either 0 (for the C_s below some threshold value C~*) or C_s (for C_s > C~*); (ⅱ) the Michaelis-Menten-Monod kinetics observed in experiments is an artifact: the pure (not contaminated by foreign factors) dependence of c oh C_s is actually such that the function c = c(C_s) has practically linear increase when C_S < C~*, and is constant, c = c(C~*) = const, when C_s > C~*; (ⅲ) the Liebig principle is strictly fulfilled: up to a feasible accuracy of observation, under no circumstances can population growth be limited (controlled) by more than one substrate component—replacement of a limiting component for another one is an instant event rather than a gradual process.