Zarmi Yair
Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, 8499000, Israel.
Heliyon. 2024 Mar 7;10(5):e27224. doi: 10.1016/j.heliyon.2024.e27224. eCollection 2024 Mar 15.
Experiments have shown that photon exploitation efficiency in unicellular algal biomass production under a pulsed-light regime with a high-photon flux is higher than the efficiency under continuous illumination with the same flux. This observation has been explained theoretically to be a consequence of the improved efficiency of exploitation of photons by Photosystem II (PS II) thanks to the combined effect of photon-absorption statistics, a rate-limiting time scale and the size of the PQ pool. Exploiting the same ideas, it is shown in this paper that, under a pulsed-light regime, there is a pulse-time length, for which the average exploitation efficiency of PS II absorbed photons is maximal. Under ideal conditions, this maximum is close to 100%. The optimal pulse-time length is roughly proportional to the size of the PQ pool, . This is clearly seen for (the average time gap between consecutive photons absorbed by the PS II-Chlorophyll antenna) of the order of 1 ms or less (corresponding to a high photon flux and/or a large photon absorption cross-section area of the antenna) and for small . The width of the plot of efficiency vs. pulse length around the optimum is then small and the optimal pulse length is well defined. As is increased beyond 1 or becomes large, the width grows, allowing for a broad choice of pulse lengths, for which efficiency is very close to the maximum. These observations open the door to future designs of highly productive bioreactors.
实验表明，在高光通量脉冲光条件下生产单细胞藻类生物质时，光子利用效率高于相同通量连续光照下的效率。从理论上解释，这种现象是由于光吸收统计、限速时间尺度和质体醌（PQ）库大小的综合作用，提高了光系统II（PS II）对光子的利用效率。基于同样的思路，本文表明，在脉冲光条件下，存在一个脉冲时长，此时PS II吸收光子的平均利用效率最大。在理想条件下，这个最大值接近100%。最佳脉冲时长大致与PQ库的大小成正比。当PS II - 叶绿素天线吸收的连续光子之间的平均时间间隔（）约为1毫秒或更短（对应高光通量和/或天线的大光子吸收横截面积）且PQ库较小时，这一点很明显。此时，效率与脉冲长度关系曲线在最优值附近的宽度较小，最佳脉冲长度定义明确。当增加到超过1或PQ库变大时，宽度增大，允许选择宽泛的脉冲长度范围，在此范围内效率非常接近最大值。这些观察结果为未来高产生物反应器的设计打开了大门。
