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

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Abstract
Growth and nitrogenase activity were studied in cultures of S. lipoferum growing with dinitrogen and combined N. 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 N. The nitrogenase activity was repressed by NH4Cl but, after exhaustion of NH3, the activity was derepressed. With respect to PO2 [partial O2 pressure], maximum nitrogenase activity in this bacterium is observed at PO2 = 0.004 atm, indicating that N2 is fixed microaerophilically by Spirillum. Free amino acid pools extracted from growing cultures of S. lipoferum is also reported, 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.
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