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 strawbeny cells. The effect of the temperature-shift interval and the shift-time point was investigated for the optimization of this strategy. In this process, strawbeny cells were grown at 30°C (the optimum temperature for cell gowth) 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 309°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 1 and 30.2 mg.L-1d1 on day 9 were achieved by a two-stage culture with a temperature-shift from 30°C after 3 d to 20°C.

High cell density and high expression of recombinant human ApoA-I_(Milano) in Escherichia coli by twice temperature-shifted induction

The effect of temperature on the formation of recombinant protein,apolipoprotein A-IMilano was investigated in the present study.The temperature of the initial growth phase was set at 30ºC,while temperature variation in induction phase was arranged in three modes.High cell-density culture of Escherichia coli and high expression of recombinant human by twice temperature-shifted induction were carried out.Experimental results showed that ApoA-IMilano reached 4.8 g/L with the final cell density of OD600,150.It was found that twice temperature-shifted induction could successfully avoid the effect of acetic acid on cell density and the expression of the product.The present study provides a basic procedure for the production of recombinant ApoA-IMilano.

Effect of temperature on batch elastase production by Bacillus sp. EL31410

The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 ℃ to 28 ℃, were evaluated in shake flask. The result indicated that 37 ℃ was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated at 30 ℃. This result was verified by batch fermentation in 5-L bio-reactor under 37 ℃ and 30 ℃ temperature, respectively. The specific cell growth rate at 37 ℃ was higher than that at 30 ℃ during earlier stage of cultivation. The maximum value [5.5 U/(h-g DCW)] of elastase formation rate occurred at 24 h at 30 ℃ compared to 4.6 U/(h-g DCW) at 30 h at 37 ℃. Based on these results, two-stage temperature shift strategy and oscillatory temperature cultivation mode were evaluated in the next study. When compared to single temperature of 37 ℃ or 30 ℃, both two-stage temperature shift strategy and oscillatory temperature strategy improved biomass but did not yield the same result as expected for elastase production. The maximum biomass (both 8.6 g/L) was achieved at 30 h at 37 ℃, but at 42 h using two-stage temperature cultivation strategy. The highest elastase production (652 U/ml) was observed at 30 ℃ in batch process. It was concluded that cultivation at constant temperature of 30 ℃ was appropriate for elastase production by Bacillus sp. EL31410.