Acting paths of elicitors on Taxol biosynthesis pathway and their synergistic effect

Many elicitors have been reported to be favorable to Taxol production in suspension cultures of Taxus cells. However, their acting paths were proved to be different, which were identified based on a quasi-steady-state transfer model. It was found that silver nitrate, ammonium citrate and methyl jasmonic acid acted on the path between Baccatin III and Taxol, while arachidonic acid and salicylic acid acted on the path before 10-deactyl Baccatin III (10-DAB). The mixtures of elicitors with different acting paths could give a synergistic effect in Taxol production while those with the same acting paths could not. A synergistic coefficient was introduced to describe the synergistic effect of elicitors quantitatively, which was defined as the ratio of the maximum Taxol concentration in the coexistence of two elicitors to the summation of the maximum Taxol concentrations in the cases with only one of the elicitors. The larger the synergistic coefficient, the more significant the synergistic effect. The synergistic coefficients of silver nitrate and arachidonic acid, ammonium citrate and arachidonic acid, ammonium citrate and salicylic acid were calculated as 1.1, 1.44 and 1,25, respectively, while those of arachidonic acid and salicylic acid, ammonium citfate and methyl jasmonic acid were only around 0.5. (C) 2002 Elsevier Science B.V. All rights reserved.