Direct Conversion of CO2 to Squaleneby Metabolically-Engineered in Cyanobacteria

Direct conversion of CO₂ to squalene

by metabolically-engineered in cyanobacteria

 Sun Young Choi¹, Sang Jun Sim², Han Min Woo^1*

¹Department of Food Science and Biotechnology, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon, Republic of Korea

²Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, Republic of Korea

^*Correspondence to hmwoo@skku.edu, TEL: +82-31-290-7808, FAX: +82-31-290-7882

Metabolic engineering of cyanobacteria has enabled photosynthetic conversion of CO₂ to value added chemicals as bio-solar cell factories [1]. The using cyanobacterial for direct production of squalene is advantage, since they can just grow carbon dioxide from air and sunlight without energy sources based on glucose. However, the production levels of squalene among several isoprenoids in engineered cyanobacteria were quite low, compared to other microbial hosts. Here, we engineered S. elongatus PCC 7942 with modular metabolic pathways consisting of the methylerythritol phosphate pathway enzymes and the squalene synthase for production of squalene, originated from 4 type microorganisms [2]. Sequentially, to increase production of squalene from CO₂ by application of the push-and-pull strategy. Squalene synthase (SQS) was fused to either a key enzyme (farnesyl diphosphate synthase) of the methylerythritol phosphate pathway or the ¥â-subunit of phycocyanin(CpcB1). Moreover, the best squalene producer was cultivated in a scalable photobioreactor (6 L) with light optimization [3]. Further development of the photo-bioprocessing conditions with strain improvement will promote establishment of an engineered bio-solar cell factory for industrial-scale CO₂ conversion. This work was financially supported by Korea CCS 2020 Program granted by National Research Foundation of Korea.

Keywords: Metabolic engineering, Cyanobacteria, Synthetic biology, Isoprenoids, squalene

Reference

[1] Woo, H.M., Solar-to-chemical and solar-to-fuel production from CO₂ by metabolically engineered microorganisms. Curr. Opin. Biotechnol. 2017, 45:1–7.

[2] Choi, S.Y.; Lee, H.J.; Choi, J.; Kim, J.; Sim, S.J.; Um, Y.; Kim, Y.; Lee, T.S.; Keasling, J.; Woo, H.M., Photosynthetic conversion of CO₂ to farnesyl diphosphate-derived phytochemicals (amorpha-4,11-diene and squalene) by engineered cyanobacteria, Biotechnol. Biofuels. 2016, 9:202.

[3] Choi, S.Y., Wang, J.Y., Kwak, H.S., Lee, S.M., Um, Y., Kim, Y., Sim, S.J., Choi. J.-I., *Woo, H.M., Improvement of squalene production from CO2 in Synechococcus elongatus PCC 7942 by metabolic engineering and scalable production in a photobioreactor (2017.07) ACS Synth. Biol. 6(7) p. 1289-1295