Oxidative Assimilation by Serratia marcescens ∗

Abstract

Summary

The oxidative assimilatory behavior of S. marcescens with various substrates is similar to that noted with other bacteria 4 , a portion of the substrate being oxidized to CO₂, a portion assimilated by the cells and the remainder converted to extracellular material not utilized readily by the cells. Oxidative activity, but not C-assimilation, was proportional to the concentration of cells over the range studied. No satisfactory explanation for this difference could be advanced. After the first 48 hours of aging of the suspensions the endogenous rate of respiration remained fairly constant for 5 days. However, the rate of exogenous respiration decreased with time but not in proportion to the viable count. Nitrogenous compounds appear to be a major endogenous substrate of S. marcescens.