INFLUENCE OF TEMPERATURE AND SUBSTRATE CONCENTRATION ON BACTERIAL-GROWTH YIELD IN SEINE RIVER WATER BATCH CULTURES

The growth of natural bacterial assemblages was monitored in 3-liter reactors under various temperature and substrate concentration conditions. The oxygen concentration was continuously monitored, and subsamples were taken at short time intervals to determine bacterial number and biomass. The rate of bacterial mortality was also determined. Bacterial growth yield was calculated as the ratio of net production (increase in biomass corrected for mortality) to gross production (net production plus oxygen consumption expressed in carbon units). Averaging 33%, the growth yield did not show any trend with temperatures in the range of 8 to 25-degrees-C but increased with the concentration of dissolved organic carbon in the range of 2 to 12 mg of C . liter-1.