Preparation and analysis of mutants of rhizospheric pseudomonads, resistant to toxic analogs of tryptophan and phenylalanine]

The absence of plasmids in strains of fluorescent pseudomonads characterized by high level of synthesis of phytohormone indole-3-acetic acid (IAA) as well as invariability of this feature in plasmid and non-plasmid variants of strain BSP8 suggests chromosomal control of IAA synthesis by the rhizosphere bacteria tested. Using toxic analogues of aromatic amino acids -5-fluorine-tryptophan and 5-methyl-tryptophan variants were obtained which synthesized and secreted only anthranilic acid. Mutants with resistance to p-fluorine-phenylalanine and capable of secreting tryptophan and/or phenylalanine were found. Testing of the secreting variants failed to reveal any differences between the levels of IAA biosynthesis in comparison with the wild-type strains.