A green light-induced alcohol production system has been successfully integrated into cyanobacteria to produce value-added chemicals without the use of expensive chemical inducers. Green-light regulated production of isobutanol and 3-methyl-1-butanol from CO2 is environmentally friendly and cost-effective. This study demonstrates that light regulation is a potential tool for producing chemicals and increasing the viability of cyanobacterial biological processes.

Therefore, in this study, we used the CcaS/CcaR two-component system [13] to produce isobutanol and 3-methyl-1-butanol (3MB) in Synechocystis sp. PCC 6803 (hereinafter referred to as PCC 6803) avoids the use of harmful chemicals and metal inducers. We previously reported the development of light-regulated gene expression systems in cyanobacteria

Protocol for green light-induced ethanol production in Synechocystis sp. PCC6803 (PCC6803). a Biosynthetic pathway for the production of isobutanol and 3-methyl-1-butanol (3MB) from captured CO2 via photosynthesis in PCC 6803. A CcaS/CcaR two-component system derived from PCC6803 was used to regulate the gene expression levels of ketoacid decarboxylase (kdc) and alcohol dehydrogenase (adh), which are involved in the production of isobutanol and 3-methyl- Required for 1-butanol.

In this study, we demonstrate the green light-induced production of isobutanol and 3-methyl-1-butanol in PCC 6803 using the CcaS/CcaR two-component system. The expression of kdc and adh genes was induced by green light irradiation. Under the control of PcpcG2, isobutanol and 3-methyl-1-butanol were successfully produced. Furthermore, additional expression of ccaR resulted in the production of 238 mg L-1 isobutanol and 75 mg L-1 3-methyl-1-butanol within 5 days. This study demonstrates the potential use of the CcaS/CcaR system for chemical production in cyanobacteria.