Hong Min-Eui, Choi Yoon Young, Sim Sang Jun
Department of Chemical Engineering, Sungkyunkwan University, Suwon 440-746, South Korea.
Department of Chemical and Biological Engineering, Korea University, Seoul 136-713, South Korea.
J Biotechnol. 2016 Jan 20;218:25-33. doi: 10.1016/j.jbiotec.2015.11.019. Epub 2015 Nov 26.
The negative effect of heat stress on the autotrophic astaxanthin production by Haematococcus pluvialis has been observed during outdoor culture in summer. Under the summer conditions, the proliferation of vegetative cells was highly halted in the green stage and the inducibility in the biosynthesis of astaxanthin was partly hindered in the red stage. Herein, under outdoor summer conditions in which variations of the diurnal temperature occur, heat-stress-driven inefficient vegetative growth of H. pluvialis was highly improved by inoculating the red cyst cells; thereby, maintaining relatively moderate intracellular carotenoid levels in the green stage. Subsequently, a remarkably enhanced astaxanthin titer was successfully obtained by supplementing 50 μM iron(II) to induce the heat stress-driven Haber-Weiss reaction in the red stage. As a result, the productivity of astaxanthin in the cells cultured under summer temperature conditions (23.4-33.5 °C) using the two methods of red cell (cyst) inoculation and the iron(Fe(2+)) supplementation was increased by 147% up to 5.53 mg/L day compared with that of the cells cultured under spring temperature conditions (17.5-27.3 °C). Our technical solutions will definitely improve the annual natural astaxanthin productivity in H. pluvialis in locations confronted by hot summer weather, particularly in large-scale closed photobioreactor systems.
在夏季室外培养过程中，已观察到热应激对雨生红球藻自养生产虾青素的负面影响。在夏季条件下，绿色阶段营养细胞的增殖高度停滞，红色阶段虾青素生物合成的诱导性部分受到阻碍。在此，在存在昼夜温度变化的室外夏季条件下，通过接种红色囊胞细胞，雨生红球藻热应激驱动的低效营养生长得到显著改善；从而在绿色阶段维持相对适中的细胞内类胡萝卜素水平。随后，通过在红色阶段补充50μM亚铁以诱导热应激驱动的哈伯-维希反应，成功获得了显著提高的虾青素产量。结果，与在春季温度条件（17.5-27.3°C）下培养的细胞相比，使用红色细胞（囊胞）接种和补充铁（Fe(2+)）这两种方法，在夏季温度条件（23.4-33.5°C）下培养的细胞中虾青素的生产率提高了147%，达到5.53mg/L·天。我们的技术解决方案肯定会提高在炎热夏季天气地区，特别是在大规模封闭式光生物反应器系统中雨生红球藻的年度天然虾青素生产率。
