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 ofthe 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