The urgency to develop sustainable fossil fuel alternatives is driven by rapidly increasing global consumption, irreversibly diminishing reserves, unpredictable geopolitical factors, fluctuating price of crude oil, growing concerns about national energy security, and serious environmental concerns surrounding immense greenhouse gas emissions mainly resulting from combustion of fossil fuels. Biofuels produced from biological resources represent a compelling alternative to fossil fuels because they are renewable and more environmentally friendly. Among various biofuels, biohydrocarbons, especially the medium- to long-chain fatty alkanes or alkenes, are widely accepted to be the ideal because they highly mimic the chemical composition and physical characteristics of petroleum-based fuels. With respect to production, microbial biosynthesis of fatty alkanes/alkenes is among the most promising ways to generate “drop-in compatible” aliphatic hydrocarbons. 

Professor LI Shengying and his Enzyme Engineering Group (EEG) at Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) have recently achieved a major breakthrough in the field of biofuels through engineering Escherichia coli for production of α-alkenes by utilizing the P450 fatty acid decarboxylase OleT_JE.  

Discovered from Jeotgalicoccus sp. ATCC 8456 in 2011 by LS9 Inc., the one-step alkene-producing pathway solely mediated by the P450 fatty acid decarboxylase OleT_JE holds great potential to be engineered into a biological α-alkene producing system. Ms. LIU Yi together with other members of the EEG investigated the enzymatic property of this unique P450 enzyme in vitro and discovered the H₂O₂–independent activity of OleT_JE for the first time. Previously, OleT_JE was thought to be a peroxygenase, which uses hydrogen peroxide as the sole electron and oxygen donor to drive catalysis. By contrast, EEG found that in presence of NADPH and O₂, this P450 enzyme can also efficiently decarboxylate fatty acids in vitro when partnering with either the fused RhFRED domain from Rhodococcus sp. or the separate flavodoxin/flavodoxin reductase from Escherichia coli. In vivo, expression of OleT_JE or OleT_JE-RhFRED in different fatty acid overproducing E. coli strains resulted in the production of multiple α-alkenes with the highest total titer of 97.6 mg/L. These results not only demonstrate an excellent example in the cytochrome P450 superfamily to have important application in production of advanced biofuels, but also suggest the direction for the future metabolic engineering work on OleT_JE. 

The research work was financially supported by National Science Foundation of China (NSFC 31270855), the Recruitment Program of Global Experts, and Boeing Company. 

Reference: Liu, Y., Wang, C., Yan, J., Zhang, W., Guan, W., Lu, X., and Li, S.* Hydrogen peroxide-independent production of α-alkenes by OleT_JE P450 fatty acid decarboxylase. Biotechnol. Biofuels 2014, 7: 28-40.  

Contact 

Prof. LI Shengying 
Lishengying (AT) qibebt.ac.cn 
Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences