[Regulation of nitrogenase activity and biosynthesis in Clostridium butyricum]

The effect of various factors on the activity and biosynthesis of nitrogenase in Clostridium butyricum was estimated by the rate of acetylene reduction at different growth phases in the static culture. The activity of nitrogenase was found to be low in vegetative cells; it increased and reached the maximum at the stage of prospore formation and decreased in the course of sporulation. The duration of different stages in the cell growth cycle depended on temperature and the composition of the medium. An increase in the rate of nitrogenase synthesis at the stage of prospore formation was favoured by the presence of sodium acetate or yeast autolysate in the medium; ammonium chloride inhibited the mechanism of nitrogenase biosynthesis. Cytoplasmic membranous structures such as tubular-vesicular or lamellar mesosomes were formed in active nitrogen fixing cells grown in a medium with yeast autolysat. Such structures were absent from cells with a low activity grown in a medium containing ammonium chloride.