Utilization of fructose by Azospirillum brasilense

Abstract

Optimum growth and acetylene reduction in Azospirillum brasilense which are comparable to those observed with organic acids, e.g., malate, succinate, pyruvate, and lactate, were obtained using fructose as the carbon source. Best yields of cell mass had been obtained with fructose and malate, while the yields were poor with other carbon sources tried. Acetylene reduction occurred at optimum levels only between pH 7.0 and 7.5. Efficiency of N2 fixation and the efficiency of the utilization of combined nitrogen were high with fructose but low with malate. Fructose as well as malate, succinate, pyruvate, and lactate were actively oxidized both in cell suspensions and cell-free extracts, while glucose, galactose, sucrose, and citrate were oxidized only in cell-free extracts.