Bernstein Hans C, McClure Ryan S, Hill Eric A, Markillie Lye Meng, Chrisler William B, Romine Margie F, McDermott Jason E, Posewitz Matthew C, Bryant Donald A, Konopka Allan E, Fredrickson James K, Beliaev Alexander S
Chemical and Biological Signature Science, Pacific Northwest National Laboratory, Richland, Washington, USA Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington, USA
Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA.
mBio. 2016 Jul 26;7(4):e00949-16. doi: 10.1128/mBio.00949-16.
Harnessing the metabolic potential of photosynthetic microbes for next-generation biotechnology objectives requires detailed scientific understanding of the physiological constraints and regulatory controls affecting carbon partitioning between biomass, metabolite storage pools, and bioproduct synthesis. We dissected the cellular mechanisms underlying the remarkable physiological robustness of the euryhaline unicellular cyanobacterium Synechococcus sp. strain PCC 7002 (Synechococcus 7002) and identify key mechanisms that allow cyanobacteria to achieve unprecedented photoautotrophic productivities (~2.5-h doubling time). Ultrafast growth of Synechococcus 7002 was supported by high rates of photosynthetic electron transfer and linked to significantly elevated transcription of precursor biosynthesis and protein translation machinery. Notably, no growth or photosynthesis inhibition signatures were observed under any of the tested experimental conditions. Finally, the ultrafast growth in Synechococcus 7002 was also linked to a 300% expansion of average cell volume. We hypothesize that this cellular adaptation is required at high irradiances to support higher cell division rates and reduce deleterious effects, corresponding to high light, through increased carbon and reductant sequestration.
Efficient coupling between photosynthesis and productivity is central to the development of biotechnology based on solar energy. Therefore, understanding the factors constraining maximum rates of carbon processing is necessary to identify regulatory mechanisms and devise strategies to overcome productivity constraints. Here, we interrogate the molecular mechanisms that operate at a systems level to allow cyanobacteria to achieve ultrafast growth. This was done by considering growth and photosynthetic kinetics with global transcription patterns. We have delineated putative biological principles that allow unicellular cyanobacteria to achieve ultrahigh growth rates through photophysiological acclimation and effective management of cellular resource under different growth regimes.
利用光合微生物的代谢潜力实现下一代生物技术目标，需要详细科学地了解影响碳在生物质、代谢物储存库和生物产品合成之间分配的生理限制和调控控制。我们剖析了广盐性单细胞蓝藻聚球藻属PCC 7002菌株（聚球藻7002）卓越生理稳健性的细胞机制，并确定了使蓝藻能够实现前所未有的光合自养生产力（约2.5小时倍增时间）的关键机制。聚球藻7002的超快生长得益于光合电子传递的高速率，并与前体生物合成和蛋白质翻译机制转录的显著提高有关。值得注意的是，在任何测试实验条件下均未观察到生长或光合作用抑制特征。最后，聚球藻7002的超快生长还与平均细胞体积扩大300%有关。我们假设，这种细胞适应性在高辐照度下是必需的，以支持更高的细胞分裂速率，并通过增加碳和还原剂的隔离来减少与高光相应的有害影响。
光合作用与生产力之间的有效耦合是基于太阳能的生物技术发展的核心。因此，了解限制碳处理最大速率的因素对于确定调控机制和设计克服生产力限制的策略是必要的。在这里，我们探究了在系统水平上运作以使蓝藻实现超快生长的分子机制。这是通过结合生长和光合动力学与全局转录模式来完成的。我们已经描绘了假定的生物学原理，这些原理使单细胞蓝藻能够通过光生理适应和在不同生长条件下对细胞资源的有效管理实现超高生长速率。
