A two-stage process with temperature-shift for enhanced anthocyanin production in strawberry cell suspension cultures

A two-stage process with temperature-shift has been developed to enhance the anthocyanin yield in suspension cultures of strawberry cells. The effect of the temperature-shift interval and the shift-time point was investigated for the optimization of this strategy. In this process, strawberry cells were grown at 30°C (the optimum temperature for cell growth) for a certain period as the first stage, with the temperature shifted to a lower temperature for the second stage. In response to the temperature shift-down, anthocyanin synthesis was stimulated and a higher content could be achieved than that at both boundary temperatures but cell growth was suppressed. When the lower boundary temperature was decreased, cell growth was lowered and a delayed, sustained maximum anthocyanin content was achieved. Anthocyanin synthesis was strongly influenced by the shift-time point but cell growth was not. Consequently, the maximum anthocyanin content of 2.7 mg·g-fresh cell^-1 was obtained on day 9 by a temperature-shift from 30°C, after 3-d culture, to 15°C. The highest anthocyanin yield of 318 mg · L^-1 on day 12 was achieved when the temperature was shifted from 30°C, after 5-d culture, to 20°C. For a global optimization of both the yield and productivity, the optimum anthocyanin yield and productivity of 272 mg · L^-1 and 30.2 mg · L^-1 · d^-1 on day 9 were achieved by a two- stage culture with a temperature-shift from 30°C after 3 d to 20°C.