Engineering cyanobacteria to improve photosynthetic production of alka(e)nes

Biotechnology for Biofuels

Weihua Wang²  Xufeng Liu¹  Xuefeng Lu² 

[1] University of Chinese Academy of Sciences, Beijing, 100049, China

[2] Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No. 189 Songling Road, Qingdao, 266101, China

关键词: Metabolic engineering;    Fatty acid;    Alka(e)ne;    Synechocystis sp. PCC6803;    Cyanobacteria;   

Others  :  798057
DOI  :  10.1186/1754-6834-6-69

 received in 2012-12-01, accepted in 2013-04-29,  发布年份 2013

【 摘 要 】

Background

Cyanobacteria can utilize solar energy and convert carbon dioxide into biofuel molecules in one single biological system. Synechocystis sp. PCC 6803 is a model cyanobacterium for basic and applied research. Alkanes are the major constituents of gasoline, diesel and jet fuels. A two-step alkane biosynthetic pathway was identified in cyanobacteria recently. It opens a door to achieve photosynthetic production of alka(e)nes with high efficiency by genetically engineering cyanobacteria.

Results

A series of Synechocystis sp. PCC6803 mutant strains have been constructed and confirmed. Overexpression of both acyl-acyl carrier protein reductase and aldehyde-deformylating oxygenase from several cyanobacteria strains led to a doubled alka(e)ne production. Redirecting the carbon flux to acyl- ACP can provide larger precursor pool for further conversion to alka(e)nes. In combination with the overexpression of alkane biosynthetic genes, alka(e)ne production was significantly improved in these engineered strains. Alka(e)ne content in a Synechocystis mutant harboring alkane biosynthetic genes over-expressed in both slr0168 and slr1556 gene loci (LX56) was 1.3% of cell dry weight, which was enhanced by 8.3 times compared with wildtype strain (0.14% of cell dry weight) cultivated in shake flasks. Both LX56 mutant and the wildtype strain were cultivated in column photo-bioreactors, and the alka(e)ne production in LX56 mutant was 26 mg/L (1.1% of cell dry weight), which was enhanced by 8 times compared with wildtype strain (0.13% of cell dry weight).

Conclusions

The extent of alka(e)ne production could correlate positively with the expression level of alkane biosynthetic genes. Redirecting the carbon flux to acyl-ACP and overexpressing alkane biosynthetic genes simultaneously can enhance alka(e)ne production in cyanobacteria effectively.

【 授权许可】

   
2013 Wang et al.; licensee BioMed Central Ltd.

【 图 表 】

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