Effect of lhcsr gene dosage on oxidative stress and light use efficiency by Chlamydomonas reinhardtii cultures
Effect of lhcsr gene dosage on oxidative stress and light use efficiency by Chlamydomonas reinhardtii cultures
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DOI：
10.1016/j.jbiotec.2020.12.023
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发表时间：
2021-02-20
影响因子：
4.1
通讯作者：
Bassi, Roberto
中科院分区：
文献类型：
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作者：
Barera, Simone;Dall'Osto, Luca;Bassi, Roberto
单细胞绿藻是一种很有前途的可再生生物燃料来源，它能从光和二氧化碳中产生富含脂质的生物质。光生物反应器的生产效率受到高细胞色素的不均匀光分布的影响，导致过量吸收的光能散热和深层遮荫。关于光防护能量耗散与生产力之间关系的对比报告已经发表。在此，我们通过比较WT和两种莱茵衣藻（Chlamydomonas reinhardtii）菌株，重新研究了能量猝灭（qE）活性、光损伤和光利用效率之间的关系，这两种菌株的LHCSR蛋白的补体不同，可以催化过剩激发能（qE）的耗散。分析了菌株在广光和CO2条件下的ROS产量、蛋白质组成、光损伤率和生产力。缺乏LHCSR1且LHCSR3基因敲低，导致qE缺失的菌株，在强光下产生O-2的速率显著提高，并伴有单线态氧释放增强和PSII光损伤。然而，突变菌株的生物量生产力仅在间歇光照条件下延迟，这表明PSII活性不是过量光照条件下的限制因素。与以往的观点相反，通过下调光保护能量耗散来驯化衣藻以提高光生物反应器中的碳同化率，在提高藻类生物量生产力方面是无效的。
Unicellular green algae, a promising source for renewable biofuels, produce lipid-rich biomass from light and CO2. Productivity in photo-bioreactors is affected by inhomogeneous light distribution from high cell pigment causing heat dissipation of light energy absorbed in excess and shading of the deep layers. Contrasting reports have been published on the relation between photoprotective energy dissipation and productivity. Here, we have re-investigated the relation between energy quenching (qE) activity, photodamage and light use efficiency by comparing WT and two Chlamydomonas reinhardtii strains differing for their complement in LHCSR proteins, which catalyse dissipation of excitation energy in excess (qE). Strains were analysed for ROS production, protein composition, rate of photodamage and productivity assessed under wide light and CO2 conditions.The strain lacking LHCSR1 and knocked down in LHCSR3, thus depleted in qE, produced O-2 at significantly higher rate under high light, accompanied by enhanced singlet oxygen release and PSII photodamage. However, biomass productivity of WT was delayed in respect for mutant strains under intermittent light conditions only, implying that PSII activity was not the limiting factor under excess light. Contrary to previous proposals, domestication of Chlamydomonas for carbon assimilation rate in photo-bioreactors by down-regulation of photoprotective energy dissipation was ineffective in increasing algal biomass productivity.