PHYSIOLOGICAL PROPERTIES OF AZOSPIRILLUM BRASILENSE SP 7 IN A MALATE LIMITED CHEMOSTAT

Abstract

Azospirillum brasilense Sp 7 was grown in a nitrogen free medium in a chemostat with malate as the sole carbon source. Several steady states were established. Malate limitation occurred at dilution rates less than 0.05 (hr^-1). Maximum growth rate and K_S were calculated from Monod's model. Poly-β-hydroxybutyrate content was found to decrease under malate limitation from 18.5% to about 2%. Protein exudation increases under these conditions. The acetylene reduction assay was shown to be not suitable for continuous culture systems. A model for the physiological properties of A. brasilense in a malate limited chemostat is developed.