Enhancing CO2 bio-mitigation by genetic engineering of cyanobacteriaElectronic supplementary information (ESI) available. See DOI: 10.1039/c2ee21124f

• Main Authors: Chen, Pei-Hong, Liu, Hsien-Lin, Chen, Yin-Ju, Cheng, Yi-Hsiang, Lin, Wei-Ling, Yeh, Chien-Hung, Chang, Chuan-Hsiung
• Format: Journal Article
• Language: English
• Published: 18.07.2012
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c2ee21124f

The increasing of atmospheric CO 2 , which is considered as a major greenhouse gas, plays a crucial role in global warming and climate change. In addition to reducing CO 2 emissions from anthropogenic activities, it is more urgent to actively remove CO 2 from the air. Carbon capture and storage (CCS) is a feasible but high-cost technology to remove CO 2 from the flue gases of coal-fired power plants. On the other hand, CO 2 sequestration by biological approaches shows potential and has the benefit that the biomass generated from the fixed CO 2 can then be utilized for other purposes. However, CO 2 bio-mitigation technology is still under development because the efficiency of CO 2 capture and fixation is too low to be applicable in industry. In this study, we enhanced a photobioreactor-based microalgal CO 2 mitigation system by combining the chemical capture/transformation of CO 2 by carbonic anhydrase (CA) with the biological fixation of captured CO 2 by cyanobacteria. We genetically engineered the cyanobacteria to produce and secrete CAs in the medium. The secreted CAs efficiently transformed dissolved CO 2 to HCO 3 . And HCO 3 was taken up by the cyanobacteria and further fixed into biomass through photosynthesis. To our knowledge, we have demonstrated for the first time that CO 2 can be sequestrated in a sustainable way through combining the chemical transformation of CO 2 with the biological CO 2 fixation in a microalgal photobioreactor system. Microalgal CO 2 bio-mitigation was enhanced by genetic engineering of cyanobacteria to produce carbonic anhydrase to capture CO 2 from the air.