BACTERIAL SUPPRESSION OF CHLORELLA BY HYDROXYLAMINE PRODUCTION

An actively nitrifying Arthrobacter sp. isolated from a lake inhibited the growth of Chlorella vulgaris. This was found to be due to hydroxylamine released by the bacterium during the oxidation of ammonium or other reduced nitrogen compounds. Plates containing Plate Count Agar streaked with Arthrobacter, accumulated 5 μg ml-1 hydroxylamine-N. Chlorella was sensitive to less than 0.24 μg ml-1 hydroxylamine-N. Non-nitrifying bacterial isolates of lacustrine origin did not demonstrate inhibiting activity. Our results indicate that nitrifying microorganisms may thus affect the population dynamics of algae in eutrophic lakes. © 1979.