GIBBERELLIN PRODUCTION IN AZOSPIRILLUM-LIPOFERUM CULTURES IS ENHANCEDBY LIGHT

The effect of white and blue light on gibberellin production of Azospi rillum lipoferum, cultured in a chemically-defined medium, was studied . Treatments were: white light (400-750 nm), blue light (400-500 nm), and dark. After 96 h at 32 degrees C and continuous shaking OD, pH and colony forming units were measured, and gibberellin production was as sessed by capillary gas chromatography-mass spectrometry-selected ion monitoring with deutero gibberellins as internal standards. The differ ent treatments did not affect the bacterial growth after 96 h of incub ation. Light increased the amount of gibberellins A, and A, found in b oth, white and blue treatments, by 2 and 3 fold respectively, as compa red with dark. Blue light had an additional effect by doubling gibbere llin A(3) production in the cultures, while the amount of gibberellin A(1) was mostly the same in both light treatments. This difference cou ld be explained through distinct pathways for gibberellin A(1) and gib berellin A(3) formation.