ABSTRACT: The present study describes and explores a model to determine bacterial growth, respiration and net ammonium remineralization as a function of the average substrate C:N ratios and concentrations of organic substrates. Several experimental data sets were used to estimate critical parameters of the model. These data sets suggest that carbon and nitrogen growth efficiencies play a central role in the computation of bacterial growth, respiration, and net ammonium remineralization. The new parameterization of these processes, which takes into account the variability of carbon and nitrogen growth efficiencies with the C:N ratio of organic substrates, agrees with the observed experimental trends. The structure of the model and the results are compared to those of other models. According to the output of our model and to experimental data, which were used to validate parts of the structure, bacterial growth increases with organic substrate concentration and decreasing C:N ratios. As a consequence, a low carbon content relative to nitrogen in the substrates does not limit bacterial growth.

KEY WORDS: Bacterial growth · Excretion · Respiration · Model · Nitrogen · Carbon

Published in AME Vol. 19, No. 2 (1999) on October 1
ISSN: 0948-3055. Copyright © Inter-Research, Oldendorf/Luhe, 1999