[P005] Poster

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[P03-373] Integrated metabolic engineering approach for photosynthetic glucose production by Picosynechococcus sp. PCC 7002

○Ayaka Tsuji¹, Kenya Tanaka¹, Yuichi Kato², Takanobu Yoshida¹, Akihiko Kondo¹, Tomohisa Hasunuma^1,3 (1. Kobe Univ. (Japan), 2. Toyama Prefectural Univ. (Japan), 3. RIKEN CSRS (Japan))

Keywords:

cyanobacteria

The development of biomanufacturing systems that convert CO₂ into valuable chemicals is an important step toward sustainable production. Cyanobacteria are promising hosts for such processes because they can fix atmospheric CO₂ using light energy through photosynthesis. In this study, we engineered the marine cyanobacterium Picosynechococcus sp. PCC 7002 to enable the secretion of glucose directly from CO₂.Previous studies using Synechococcus elongatus PCC 7942 reported glucose secretion through disruption of glucokinase genes and acquisition of glucose export activity via spontaneous mutation¹. However, these systems relied on sucrose hydrolysis, which generates equimolar fructose as a byproduct. The conversion of fructose to fructose-6-phosphate consumes ATP, potentially reducing the overall energy efficiency of glucose production. To overcome these limitations, we implemented three metabolic engineering strategies: (i) disruption of the glucokinase gene to prevent glucose reassimilation, (ii) introduction of a metabolic pathway that produces glucose without generating fructose to redirect carbon flux, and (iii) introduction of a glucose export system to enhance extracellular secretion. The strain combining all three modifications achieved the highest level of glucose secretion. These results demonstrate the effectiveness of an integrated metabolic engineering strategy that combines carbon flux control and transporter engineering to enable photosynthetic glucose production from CO₂.

(1) Zhang, S.; Sun, J.; Feng, D.; Sun, H.; Cui, J.; Zeng, X.; Wu, Y.; Luan, G.; Lu, X. Unlocking the potentials of cyanobacterial photosynthesis for directly converting carbon dioxide into glucose. Nature Communications 2023, 14 (1)