Cyanobacteria, such as Synechocystis, have recently become attractive hosts for sustainable production of biofuels and bio-fixation of CO₂ due to their genetic tractability and relatively fast growth. Cultivation of cyanobacteria requires shear stress, which is generated by mixing and air bubbling. In the present work, the impact of shear stress caused by stirring and air bubbling on the growth and pigment production of Synechocystis sp. PCC 6803 is investigated. For this purpose, agitated and airlift bubble column photobioreactors were used. The results showed that the growth and yield production were improved by mixing the culture system. However, there is a limit to this improvement: In the case of air bubbling, increasing shear stress (by rising air bubbling flow rate) to more than 185 mPa did not show any significant growth enhancement, while increasing the shear stress from 40 to 185 mPa improved the yield production up to 85%. At the optimal stirring rate, the yield production in the stirred photobioreactors increased by about 60% as compared to that of unstirred culture. The measurements of chlorophyll_a and carotenoid showed a strong correlation between biomass production and total pigment content. The highest level of cellular pigment (pigment per cell) was detected at the early stages of culture growth when cells were preparing for the rapid exponential growth phase.

中文翻译：

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集胞藻的生长和色素产生。剪切应力下的 ​​PCC 6803

蓝藻，如集胞藻，由于其遗传易处理性和相对快速的生长，最近已成为可持续生产生物燃料和生物固定 CO _{2的有吸引力的宿主。}蓝藻的培养需要剪切应力，这是通过混合和鼓泡产生的。在目前的工作中，搅拌和鼓泡引起的剪切应力对集胞藻生长和色素产生的影响sp。PCC 6803 正在调查中。为此，使用了搅拌式和气升式气泡柱光生物反应器。结果表明，混合培养体系提高了生长和产量。然而，这种改进是有限度的：在空气鼓泡的情况下，将剪切应力（通过提高空气鼓泡流速）增加到 185 mPa 以上并没有显示任何显着的生长增强，而将剪切应力从 40 增加到 185 mPa 将产量提高高达 85%。在最佳搅拌速率下，与未搅拌培养相比，搅拌光生物反应器的产量增加了约 60%。_叶绿素a的测定和类胡萝卜素在生物量产量和总色素含量之间表现出很强的相关性。当细胞准备进入快速指数生长期时，在培养物生长的早期阶段检测到了最高水平的细胞色素（每个细胞的色素）。