Comparative study of the growth of two strains ofNitrobacter in batch and continuous culture.

Growth kinetics of 2Nitrobacter strains (N.w. and L) coexisting in the same soil are studied in batch and continuous culture. Monod's parameters are estimated numerically from experimental data in the case of the batch experiment, and from steady-state equations in the case of the chemostat. In both cases, the 2 strains show different values for their growth parameters. N.w. may be characterized by its highμ max-Ks values, relative to strain L. But for each strain,μ max is significantly lowered between batch and continuous culture. In this latter case, at N-NO2 (-) concentrations less than 1.5μg·ml(-1), the 2 strains exhibit similar growth rates showing that for concentrations of the limiting substrate prevailing in the soil, they may compete for this substrate.