Ammonia as an important nitrogen source for the photosynthetic growth of <italic>Rhodospirillum rubrum</italic>

Abstract

The growth of Rhodospirillum rubrum strain K was poor in a glutamatemalate (G-3-X) medium under light-anaerobic conditions. The supplement of ammonia to the G-3-X medium remarkably stimulated the growth. No such stimulation by ammonia was observed under dark-aerobic conditions. The other bacterium, strain M, also showed a similar tendency for the ammonia requirement, though its growth in the G-3-X medium was much more abundant as compared to that of strain K. Casamino acid was found to contain stimulating factors for growth. Among the amino acids, arginine and/or histidine were effective. The other factor in casamino acid was found to be ammonia. The crude extracts of strains K and M contained glutamic dehydrogenase as judged by the formation of glutamate from α-ketoglutarate and ammonia. The highly reduced state of the cell components under lightanaerobic conditions, appears to limit the formation of ammonia from glutamate. Ammonia was a preferable nitrogen source to glutamate under the conditions employed.