Hydrocarbon production in genetically engineered cyanobacteria
Final Report Abstract
Alkane production in cyanobacteria may positively correlate with the AAR / ADO expression levels and enzyme activities. AAR and ADO from different cyanobacterial strains with distinct enzyme activities will provide genetic parts for efficient alkane production. Promoters with distinct strength will drive AAR and ADO gene expression to appropriate levels. We performed series of comparative promoter analyses using different reporters and characterizing promoters not tested before. The use of native promoters driving the expression of regulatory RNAs is an attractive choice because their expression is frequently tightly regulated and bound to a particular stimulating molecule of inductor. Moreover, from a commercial point of view, these regulatory sequences represent a previously untapped resource, i.e., are not yet covered by intellectual property rights. A sensitive fluorescent biosensor for the rapid monitoring of intracellular alkane biosynthesis was developed. Using GFP as reporter, the biosensor could actively respond to the intracellular alkane products. These results also suggest the feasibility of developing high-throughput strategies basing on the alkane biosensor device, and thus will greatly facilitate the application of directed evolution strategies to further improve the alkane-producing microbial cell factories. It is indicated that alkane biosynthesis plays important roles in stress responses of cyanobacteria. Free fatty acids will be released from lipid turnover or degradation of cyanobacteria cells when respond to stress conditions. Excess free fatty acids can be converted to less-toxic alka(e)nes to reduce the damage by cyanobacteria.
Publications
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(2014) Alkane biosynthesis genes in cyanobacteria and their transcriptional organization in Synechocystis sp. PCC 6803. Front. Bioeng. Biotechnol.: Synth. Biol. 2, 24
Klähn S., Baumgartner D., Pfreundt U., Voigt K., Steglich C., Hess W. R.
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(2015) Genetically assembled fluorescent biosensor for in situ detection of bio-synthesized alkanes. Scientific Reports 5, 10907
Wu W., Zhang L., Yao L., Tan X., Liu X., Lu X.
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(2017) Acclimation of oxygenic photosynthesis to iron starvation is controlled by the sRNA IsaR1. Current Biology
Georg J., Kostova G., Vuorijoki L., Schön V., Kadowaki T., Huokko T., Baumgartner D., Müller M., Klähn S., Allahverdiyeva Y., Hihara Y., Futschik M., Aro E.M., Hess W.R.
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(2017) Draft genome sequences of nine cyanobacterial strains from diverse habitats. Genome Announcements 5 (9), e01676-16
Zhu T., Hou S., Lu X., Hess W.R.
