REGENERATION OF PHOSPHORUS AND NITROGEN BY 4 SPECIES OF HETEROTROPHICNANOFLAGELLATES FEEDING ON 3 NUTRITIONAL STATES OF A SINGLE BACTERIALSTRAIN

Three physiological states of a single bacterial strain, namely, balan ced, phosphorus-rich, and nitrogen-rich bacteria, were obtained by cul turing a bacterial strain in chemostats under three different nutrient regimens. Each was shown to be distinctly different in elemental comp osition with respect to C/N/P ratio. These bacteria were fed to four s pecies of heterotrophic nanoflagellates in batch culture grazing exper iments, and the percent regeneration efficiencies of bacterium-bound n itrogen and phosphorus by the flagellates were compared. All flagellat e species regenerated comparable amounts of nitrogen, which was though t to be due to their similar internal C/N ratios. There was, however, interspecies variation with regard to phosphorus regeneration: the two faster growing species (Paraphysomonas imperforata and Bodo designis) released significantly more phosphorus than the two slower-growing sp ecies (Stephanoeca diplocostata and Jakoba libera). The observed diffe rences were thought to have been influenced by a combination of life c ycle strategies and internal C/P ratios.