Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, 266101, China.
University of Chinese Academy of Sciences, Beijing, China.
Appl Microbiol Biotechnol. 2016 Sep;100(18):7865-75. doi: 10.1007/s00253-016-7510-z. Epub 2016 Apr 14.
It is important to obtain abundant sugar feedstocks economically and sustainably for bio-fermentation industry, especially for producing cheap biofuels and biochemicals. Besides plant biomass, photosynthetic cyanobacteria have also been considered to be potential microbe candidates for sustainable production of carbohydrate feedstocks. As the fastest growing cyanobacterium reported so far, Synechococcus elongatus UTEX 2973 (Syn2973) might have huge potential for bioproduction. In this study, we explored the potentials of this strain as photo-bioreactors for sucrose and glycogen production. Under nitrogen-replete condition, Syn2973 could accumulate glycogen with a rate of 0.75 g L(-1) day(-1) at the exponential phase and reach a glycogen content as high as 51 % of the dry cell weight (DCW) at the stationary phase. By introducing a sucrose transporter CscB, Syn2973 was endowed with an ability to secrete over 94 % sucrose out of cells under salt stress condition. The highest extracellular sucrose productivity reached 35.5 mg L(-1) h(-1) for the Syn2973 strain expressing cscB, which contained the similar amounts of intracellular glycogen with the wild type. Potassium chloride was firstly proved to induce sucrose accumulation as well as sodium chloride in Syn2973. By semi-continuous culturing, 8.7 g L(-1) sucrose was produced by the cscB-expressing strain of Syn2973 in 21 days. These results support that Syn2973 is a promising candidate with great potential for production of sugars.
从经济和可持续的角度获取丰富的糖原料对于生物发酵工业很重要，特别是对于生产廉价的生物燃料和生物化学物质。除了植物生物质，光合蓝藻也被认为是可持续生产碳水化合物原料的潜在微生物候选物。作为迄今为止报道的生长最快的蓝藻，集胞藻 UTEX 2973（Syn2973）可能具有巨大的生物生产潜力。在这项研究中，我们探索了该菌株作为蔗糖和糖原生产光生物反应器的潜力。在氮充足的条件下，Syn2973 在指数生长期以 0.75 g L(-1) day(-1)的速度积累糖原，在静止期达到高达 51%的干细胞重量（DCW）的糖原含量。通过引入蔗糖转运蛋白 CscB，Syn2973在盐胁迫条件下能够将超过 94%的蔗糖分泌到细胞外。表达 cscB 的 Syn2973 菌株的最高细胞外蔗糖生产力达到 35.5 mg L(-1) h(-1)，其细胞内糖原含量与野生型相似。首次证明氯化钾和氯化钠都能诱导 Syn2973 中蔗糖的积累。通过半连续培养，表达 cscB 的 Syn2973 菌株在 21 天内生产了 8.7 g L(-1)的蔗糖。这些结果表明，Syn2973 是一种很有前途的候选菌株，具有巨大的产糖潜力。
