碳和氮代谢被抑制诱导雨生红球藻细胞内虾青素的合成

为研究雨生红球藻(Haematococcus pluvialis)合成虾青素的机理,文中分析了不同诱导条件下藻细胞内氮和碳代谢的变化。结果表明:强光照(HL)、添加乙酸钠(AA)、缺氮(NF)和缺磷(PF)都直接或间接地影响了雨生红球藻细胞内1,5-二磷酸核酮糖羧化酶(Rub isco)和硝酸还原酶(NR)的活性,导致2种酶的活性大幅度下降。只有当Rub isco和NR的活性降到非常低的水平时,藻细胞才开始合成虾青素。与此相反,对照(CK)中这2种酶的活性一直较高,但细胞内没有虾青素积累。由于Rub isco和NR是雨生红球藻碳代谢和氮代谢的关键酶,因此碳和氮代谢被抑制是诱导雨生红球藻合成虾青素的原因。

Biosynthesis of astaxanthin in Haematococcus pluvialis caused by suppression on nitrogen and carbon metabolisms

To study the synthetic mechanism of astaxanthin in Haematococcus pluvialis,the changes of nitrogen and carbon metabolisms in the algal cells growing under different inducing conditions were investigated.It showed that high light,acetate-supplementation,nitrogen and phosphate depletion all affected ribulose-1,5-bisphosphate carboxylase(Rubisco) and nitrate reductase(NR) either directly or indirectly,resulting in ultimate decrease of enzyme activities.The biosynthesis of astaxanthin in H.pluvialis occurred only when Rubisco and NR activities fell to rather low levels.By contrast,in control(CK) both enzyme activities maintained high levels under normal condition,but astaxanthin synthesis did not take place at all.These results strongly suggest that astaxanthin formation in H.pluvialis is caused by suppression on nitrogen and carbon metabolisms.