肉苁蓉细胞继代培养过程中的褐变控制

肉苁蓉细胞在培养过程中易发生褐变. 通过对褐变前后细胞的多酚含量、褐变强度与多酚氧化酶活性的比较，确定了肉苁蓉多酚氧化酶酶促褐变是肉苁蓉褐变的主要原因. 通过测定不同pH下的酶活性，确定肉苁蓉多酚氧化酶的最适pH为5.8~6.0. 在最适pH条件下，比较了维生素C(Vc)、柠檬酸、Na2SO3等对肉苁蓉多酚氧化酶活性的影响，发现这几种物质对多酚氧化酶活性均有抑制效果，其中Vc随浓度的增大对多酚氧化酶的抑制作用显著，当其浓度达到0.6 mg/L时，多酚氧化酶的酶活降低为最适酶活的5.1%. 进一步在肉苁蓉细胞继代培养中添加Vc配合使用活性炭，优化出Vc-活性炭培养基. 添加1.0 g/L活性炭和3.0 mg/L Vc(附加1.0 mg/L IAA和4.0 mg/L KT)的B5培养基能有效抑制细胞褐变，使细胞褐变程度仅为原来的21%，细胞生长旺盛，最大细胞相对增长量(干重)提高了25.4%.

Control of Browning in Cell Subculture of Cistanche deserticola

Browning forms easily during cell culture of Cistanche deserticola. By comparing the content of phenol,browning degree and activity of polyphenol oxidase (PPO) between browning and unbrowning cells,enzymatic action of PPO was considered as the main factor of browning. The optimum pH of PPO is from 5.8 to 6.0 by determining the activity of PPO with pH from 2.0 to 8.0. The effects of inhibitors,including vitamin C (Vc),citric acid and sodium sulfite,on the activity of PPO of Cistanche deserticola were investigated at the optimum pH. These inhibitors all can restrain the activity of PPO,Vc can restrain prominently the activity of PPO,increasing its concentration. When the concentration of Vc reached 0.6 mg/L,the activity of PPO decreased to 5.1% of the optimum activity of PPO. Then the medium containing activated carbon and VC for cell subculture was obtained. The optimal B5 medium including 1.0 g/L activated carbon,3.0 mg/L Vc,1.0 mg/L IAA and 4.0 mg/L KT can effectively restrain browning of cells. The browning degree of the cells in the optimal B5 medium decreased to 21%. The cells of Cistanche deserticola grew better in the optimal medium and the maximum relative increment of cell growth (dry weight) was 25.4%.