Istituto per lo Studio degli Ecosistemi del Consiglio Nazionale delle Ricerche (CNR-ISE), via Madonna del Piano 10, 50019 Sesto Fiorentino, Firenze, Italy.
J Biotechnol. 2012 Feb 20;157(4):620-7. doi: 10.1016/j.jbiotec.2011.06.040. Epub 2011 Jul 8.
In the past decade, H₂ production using the green microalga Chlamydomonas reinhardtii has been extensively studied under laboratory-scale photobioreactors, while information on outdoor cultures is still lacking. In this paper, the results of experiments conducted with sulfur-deprived cultures of C. reinhardtii carried out in a 50-L horizontal tubular photobioreactor are presented. Hydrogen production experiments were carried out under both artificial and direct solar light. In both cases, the H₂ output attained was 18-20% of what obtained in the laboratory. However, no significant changes in the H₂ production were observed when cells grown outdoors were tested under laboratory conditions. Chlorophyll fluorescence measurements showed that outdoor cultures were subjected to strong photo-inhibition, due to the combination of high solar light intensity and sulfur-deprivation. Indeed, H₂ production was only achieved outdoors when cultures were previously acclimated to sunlight, a condition that caused a number of physiological changes, namely: (i) a decrease in the chlorophyll content per unit of dry weight; (ii) an increase in the photosynthesis and respiration rates, and (iii) a higher induction of the xanthophyll cycle pigments as compared to non-acclimated cultures. It was concluded that the reduced H₂ output achieved in the 50-L photobioreactor was due to the different illumination pattern to which the cultures were exposed (one-sided vs. two-sided illumination provided in the laboratory), as well as to the great difference in the mixing times (60 min vs. 15.5s achieved in the lab-scale photobioreactor). To the very best of our knowledge this is the first time that H₂ production with green algae has been achieved by means of solar light.
在过去的十年中，使用绿藻莱茵衣藻在实验室规模的光生物反应器中广泛研究了 H₂ 的生产，而有关户外培养的信息仍然缺乏。本文介绍了在 50-L 水平管式光生物反应器中用硫饥饿的莱茵衣藻培养物进行的实验结果。在人工和直接太阳光下进行了氢气生产实验。在这两种情况下，获得的 H₂ 产量均为实验室获得产量的 18-20%。然而，当在实验室条件下测试户外培养物时，H₂ 产量没有观察到明显变化。叶绿素荧光测量表明，由于高太阳强度和硫饥饿的结合，户外培养物受到强烈的光抑制。实际上，只有当培养物预先适应阳光时，才能在户外获得 H₂ 生产，这种条件会导致许多生理变化，即：（i）单位干重的叶绿素含量减少；（ii）光合作用和呼吸作用速率增加；（iii）叶黄素循环色素的诱导更高与未适应的培养物相比。结论是，在 50-L 光生物反应器中获得的 H₂ 产量降低是由于培养物所暴露的不同照明模式（实验室中提供的单面和双面照明）以及混合时间的巨大差异所致（实验室规模的光生物反应器中达到的 60 分钟与 15.5 秒）。据我们所知，这是首次通过太阳光实现绿藻的 H₂ 生产。
