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The effects of both initial sucrose concentration and sucrose feeding on cell growth and accumulation of taxane diterpene (taxuyunnanine C) in suspension cultures of Taxus chinensis were investigated in detail. For the initial sucrose concentrations of 20, 30, 40 and 50 g/l, the cell growth was repressed by the later two high levels (i.e. 40 and 50 g/l of initial sucrose) with a relatively longer lag phase. Combination of initial low sucrose concentration (20 g/l) and subsequent sucrose feeding during cultivation (fed-batch culture) improved the cell growth, and a final cell concentration of over 27 g dry cells/l was successfully achieved after 23 days of cultivation. The time course of the taxane formation was related to the cell growth profile. For example, in the cell cultivation with under 30 g/l of initial sucrose, the specific taxane production (content) was relatively low when the cells were under active growth, but sharply increased up to ∼14 mg/g DW when the cells approached the stationary phase. In the batch cultures with an increase in initial sucrose concentration from 20 to 50 g/l, both the taxane content and productivity were decreased. In the fed-batch cultures, a relatively high taxane content was obtained at the end of cultivation; both a very high taxane production of 274.4 mg/l and a high productivity of 9.3 mg/(l day) were successfully achieved by feeding 20 g/l of sucrose (on day 7) to the cell cultures. |
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