Inhibition of Starch Synthesis Results in Overproduction of Lipids in Chlamydomonas reinhardtii
Inhibition of Starch Synthesis Results in Overproduction of Lipids in Chlamydomonas reinhardtii
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DOI：
10.1002/bit.22807
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发表时间：
2010-10-01
影响因子：
3.8
通讯作者：
Hu, Qiang
中科院分区：
文献类型：
--
作者：
Li, Yantao;Han, Danxiang;Hu, Qiang
淀粉和中性脂质是许多微藻和植物中两种主要的碳储存化合物。脂质更富含能量，经常被用作食物和燃料原料。脂质生物合成途径的基因工程过量生产脂质只取得了有限的成功。我们推测，通过阻断竞争途径产生淀粉，中性脂质的过度生产可能会实现。利用绿色衣藻及其低淀粉和无淀粉突变体对这一假设进行了检验。结果表明，在强光和氮饥饿条件下，突变体的中性脂含量和中性脂/总脂比值显著增加。BAFJ 5是ADP-葡萄糖焦磷酸化酶小亚基缺陷突变体之一，中性脂质和总脂质的积累分别高达干重（DW）的32.6%和46.4%，分别比野生型高出8倍和3.5倍。这些结果证实了通过将光合同化碳从淀粉合成转向中性脂质合成来增加脂质产量的可行性。然而，在低淀粉和无淀粉突变体中观察到一些生长障碍，这可能是由于PSII中能量分配的改变，更多的激发能作为热量耗散，而光化学转化较少。该研究表明，所选突变体的生物量和脂质生产可以通过生理操作来改善。Biotechnol. Bioeng. 2010;107：258-268. (c)2010 Wiley Periodicals，Inc.
Starch and neutral lipids are two major carbon storage compounds in many microalgae and plants. Lipids are more energy rich and have often been used as food and fuel feedstocks. Genetic engineering of the lipid biosynthesis pathway to overproduce lipid has achieved only limited success. We hypothesize that through blocking the competing pathway to produce starch, overproduction of neutral lipid may be achieved. This hypothesis was tested using the green microalga Chlamydomonas reinhardtii and its low starch and starchless mutants. We discovered that a dramatic increase in neutral lipid content and the neutral lipid/total lipid ratio occurred among the mutants under high light and nitrogen starvation. BAFJ5, one of the mutants defective in the small subunit of ADP-glucose pyrophosphorylase, accumulated neutral and total lipid of up to 32.6% and 46.4% of dry weight (DW) or 8- and 3.5-fold higher, respectively, than the wild-type. These results confirmed the feasibility of increasing lipid production through redirecting photosynthetically assimilated carbon away from starch synthesis to neutral lipid synthesis. However, some growth impairment was observed in the low starch and starchless mutants, possibly due to altered energy partitioning in PSII, with more excitation energy dissipated as heat and less to photochemical conversion. This study demonstrated that biomass and lipid production by the selected mutants can be improved by physiological manipulation. Biotechnol. Bioeng. 2010;107: 258-268. (c) 2010 Wiley Periodicals, Inc.