ACETATE AS A CALCIUM-SPARING FACTOR IN NITROGEN FIXATION BY AZOTOBACTER VINELANDII

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Abstract
The requirement for the Ca ion in nitrogen fixation by Azotobacter vinelandii O is negated when sodium acetate is supplied in the growth media. At a Ca ion level of 10-5 to -10-6 [image], the organism will not initiate growth on N2 but will on NH4+. Addition of sodium acetate to the Ca-deficient medium allows growth to occur in the absence of fixed nitrogen. Ethyl alcohol alone or potassium malate plus sucrose can also replace this Ca requirement. The following compounds were found to be ineffective in substituting for acetate in reference to reducing the requirement of Ca ion glucose, fructose, ribose, dihydroxyacetone, sodium pyruvate, potassium glycolate, potassium glyoxylate, thioamine, or thoctic acid.