Statistical analysis of growth limitations in Paracoccus denitrificans: an experiment with a completely randomized two-way factorial design with replications.

Cultivation of microorganisms under growth limitation is a widely used technique in microbiology. The relevant investigations, though seemingly based on straightforward experiments, have generated conflicting results, e.g., concerning molar growth yields. The purpose of this paper is to show that discrepancies in the literature could be solved if more attention were paid to methodology, especially statistics. New experimental results, concerning growth limitations in Paracoccus denitrificans, will exemplify this. They include the following items. Two limitations, one of them being succinate limitation, were established in the present study. Molar growth yields on succinate were 41 g X mol-1 for succinate limitation (95% confidence limits were 38 and 44) and 32 g X mol-1 for the other limitation (95% confidence limits were 29 and 35). The latter result is compatible with sulphate limitation, but the present experimental design does not really permit this conclusion.