Abstract

The aim of this work was a comparative study of S-repleted and S-depleted photoautotrophic cultures of Chlamydomonas reinhardtii under aerobic and anoxic conditions with the main focus on PSII activity. For that we used photobioreactor with short light path connected on-line to PAM fluorometer and cultivated microalgae in twice concentrated HS medium to avoid any uncontrolled limitation by mineral elements. Photoautotrophic cultures grown under Ar + CO₂ gas mixture did not reach the same Chl (a + b) concentration as control culture (grown under air + CO₂). At pO₂ 40% of air saturation (96 µM O₂), the actual quantum yield of PSII started to decrease. Under microaerobic conditions when cultures stopped growing, the most significant changes in PSII function were observed. Maximum quantum yield F_v/F_m decreased significantly along with performance index, PIabs. It was accompanied by increase of fluorescence at J point, V_j. Results indicate that microaerobic conditions are stressful for photoautotrophic cultures. Photoautotrophic cultures of microalgae under S-deprivation in aerobic or anaerobic conditions showed similar behavior as photoheterotrophic ones described earlier. However, photoautotrophic cultures during anaerobiosis establishment did not show sharp “switch off” effect of actual quantum yield. We show also that S-deprivation under air or argon as well as the growth under Ar + CO₂ cause significant increase of initial rise of fluorescence, which indicates that PSII and oxygen-evolving complex might be disintegrated.

中文翻译：

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莱茵衣藻的光合自养培养：硫缺乏，缺氧和产氢

摘要

这项工作的目的是对有氧和无氧条件下的莱茵衣藻的S重复和S耗尽的光合自养培养物进行比较研究，主要研究PSII活性。为此，我们使用光路短的光生物反应器在线连接到PAM荧光计，并在两次浓缩的HS培养基中培养微藻，以避免不受矿物元素的任何不可控制的限制。在Ar + CO ₂气体混合物下生长的自养养分培养物未达到与对照培养物（在空气+ CO ₂下生长）相同的Chl（a + b）浓度。在pO _2时，空气饱和度为40％（96 µM O ₂），PSII的实际量子产率开始下降。在微需氧条件下，当培养物停止生长时，观察到PSII功能的最显着变化。最大量子产率F _v / F _m随性能指标PIabs显着降低。伴随着在J点V _j的荧光增加。结果表明微需氧条件对光自养培养物有压力。在需氧或厌氧条件下，S剥夺作用下微藻的光合自养培养物表现出与前述光异养性相似的行为。但是，厌氧菌建立过程中的光合自养培养没有显示出实际量子产率的明显“关闭”效应。我们还表明，在空气或氩气下的S剥夺以及在Ar + CO ₂下的生长导致荧光的初始上升显着增加，这表明PSII和析氧复合物可能会分解。