Intensification of gibberellin synthesis by surfactant producers Acinetobacter calcoaceticus IMV B-7241 and Rhodococcus erythropolis IMV Ac-5017

Abstract

The surfactant-producing strains Acinetobacter calcoaceticusIMV B-7241 and Rhodococcus erythropolis IMV Ac-5017 can synthesize gibberellin phytohormones, although generally at low levels. One approach to enhance gibberellin production is the introduction of biosynthetic precursors into the cultivation medium, which may stimulate metabolic flux toward hormone formation. In the presence of 300–500 mg/L erythritol as an exogenous precursor, and regardless of the carbon source used in the culture medium (refined oil, ethanol, or biodiesel production waste), the concentration of biologically active gibberellins GA₃ and GA₄ synthesized by Acinetobacter calcoaceticus and Rhodococcus erythropolis increased significantly by approximately 1.5- to 16-fold relative to cultures grown without erythritol. This pronounced enhancement indicates that erythritol effectively increases metabolic flux through the gibberellin biosynthetic pathway. Under such conditions, a 1.4–1.7-time increase in the C-methyl-D-erythritol-4-phosphatecytidylyl transferase activity, a key enzyme of these phytohormones biosynthesis in the methyl-erythritol-4-phosphate pathway, was observed in the cells of both strains. The presence of erythritol in the cultivation medium of strains IMV B-7241 and Ac-5017 didn`t affect the surfactant synthesis. The data obtained provide a basis for the development of an efficient, integrated technology for the cosynthesis of surface-active compounds and phytohormones, with potential applications in plant production.