Using a rapid continuous flow system (D=1), growth rates and molar growth yields of free and adsorbed cells of Escherichia coli were determined with glucose as a limiting substrate. In this system, free cells were continuously removed and a steady state in cell or substrate concentration in the liquid phase of culture was realized by the growth of adsorbed cells. Growth constants of free cells, µ and Y, were obtained from a washout curve of free cells and a corresponding curve of increase of a

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... ubstrate. Growth constants of adsorbed cells, µa and Ya, were obtained from steady state concentrations of cell and substrate in the liquid phase of culture during cultivation of adsorbed cells. The growth rate of adsorbed cells depended both on substrate concentration and the amount of adsorbed cells. Saturation constants for growth, KS, with glucose as a substrate were extremely high and they also depended on the amount of adsorbed cells. The maximal growth rate and the molar growth yield of adsorbed cells were much higher than those of free cells. In studying bacterial growth in a heterogeneous system, a problem is how to estimate the growth constants of adsorbed cells distinguishing them from those of free cells and there have been comparatively few reports in this direction. LARSEN and DIMMIcK (1) showed that the growth of Serratia marcescens was much accelerated on a glass surface. PANIKOV et al. (2) proposed a kinetic model for the growth of a yeast in a sand column, making a distinction between free and adsorbed states. Previously, one of the authors showed that the growth rate of adsorbed cells and that of free cells could be estimated separately in a rapid continuous flow culture with a dilution rate larger than a critical one (DCD~) by the constant removal of free cells from the system and showed that the growth rate of Escherichia coli and Bacillus subtilis or the spore formation rate of B. subtilis was much accelerated 287