The potential of Synechococcus elongatus UTEX 2973 for sugar feedstock production
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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.
KeywordsGlycogen Sucrose Salt stress Synechococcus elongatus UTEX 2973
We thank Dr. Cheng Li, Quan Luo, and Yangkai Duan for valuable discussions.
Compliance with ethical standards
This work was supported by the National Science Fund for Distinguished Young Scholars of China (31525002 to X. Lu), the Excellent Youth Award of the Shandong Natural Science Foundation (JQ201306 to X. Lu), the Shandong Taishan Scholarship (X. Lu), the National Science Foundation of China (31301018 to X. Tan), the State Oceanic Administration (SOA) Global Change and Air-Sea Interaction Program (GASI-03-01-02-05 to X. Tan), and the Youth Innovation Promotion Association (X. Tan).
Conflict of interest
The authors declare that they have no competing interests.
This article does not contain any studies with human participants or animals.
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