PRODUCTION OF INDOLE-3-ACETIC-ACID AND GIBBERELLINS A(1) AND A(3) BY ACETOBACTER-DIAZOTROPHICUS AND HERBASPIRILLUM-SEROPEDICAE IN CHEMICALLY-DEFINED CULTURE MEDIA

The characterization by capillary gas chromatography-mass spectrometry of the plant hormones indole-3-acetic acid and the gibberellins GA(1) and GA(3) from chemically-defined cultures of Acetobacter diazotrophi cus and Herbaspirillum seropedicae is reported. Both bacteria are endo phytic in gramineae species where they promote growth and yield. Quant ification was also done by selected ion monitoring with [17,17-H-2(2)] -Gibberellin A(1), [17,17-H-2(2)]-Gibberellin A(3) and [C-13(6)]-indol e-3-acetic acid as internal standards. The results presented show the importance of studying phytohormonal production when the interrelation ships between plants and microorganisms are analyzed and may help expl ain the beneficial effects of endophytic bacteria to the host plant, a s has been demonstrated previously for Azospirillum spp.