Nitrogen metabolism of Frankia strain, Cc01, Mg+, At4 and Hr18

Abstract

The composition and levels of amino acids in four Frankia strains isolated from different actinorhizal plants, were determined. Minor differences in the amino acid profiles were noted with GLN (GLU) being the major amino acid in all four strains. Enzyme actives of ammonia metabolism, GS (glutamine synthetase), GOGAT (glutamate synthetase), and GDH (glutamate dehydrogenase), were also measured. In strains At4 and Hr18, GS and GOGAT activity levels were elevated in N2-grown cells but significant amounts of GDH activity were present in ammonia-grown cells. No GDH was detected in strain Cc01 and Mg+. The characters of heat-stable and heat-labile GSs were described. In N2-fixing cells, the ATP and amino acid content was much lower, but ammonia content was higher than in NH inf4 sup+ -grown cells.