Biosynthesis of Indole-3-acetic Acid in Ginseng Growth-promoting Pseudomonas fluorescens KGPP 207

The ginseng growth-promoting bacterium Pseudomonas fluorescens KGPP 207 synthesized indole-3- acetic acid (IAA) from L-tryptophan, indole-3-pyruvic acid (IPyA), and indole-3-acetaldehyde (IAAld), but not from indole-3-acetamide (lAM) and other intermediates of various IAA biosynthetic pathways in the experiment with indole compound supplemented cell suspensions. TLC, HPLC, and GC-MS analyses revealed the presence of IPyA, indole-3-ethanol, indole-3-lactic acid and its methyl ester, IAA and its methyl, and ethyl esters in the culture supernatant of the bacterium. IAAld was detected in the supernatant using sodium bisulfite and TLC. The results indicate that unlike gall-forming bacteria which can synthesize IAA by lAM, the indole-3-pyruvic acid pathway is the route for IAA biosynthesis in this beneficial strain of P. fluorescens.