INFLUENCE OF NITROGEN ON GROWTH, FREE AMINO ACIDS AND NITROGENASE ACTIVITY IN SPIRILLUM LIPOFERUM

Abstract

Growth and nitrogenase activity were studied in cultures of Spirillum lipoferum growing with dinitrogen and combined nitrogen. Not much difference is observed in the growth rates in culture growing with and without dinitrogen except that the lag phase is shortened in culture growing with combined nitrogen. The nitrogenase activity was repressed by ammonium chloride but, after exhaustion of ammonia, the activity was derepressed. With respect to P_O2, maximum nitrogenase activity in this bacterium is observed at P_O2=0.004atm, indicating that nitrogen is fixed microaerophilically by Spirillum. Free amino acid pools extracted from growing cultures of Spirillum lipoferum is also reported here, suggesting that the free amino acid pool contains a variety of amino acids with glutamic acid and amide glutamine being present in much higher concentrations than others.