Enhancing CO sub(2) bio-mitigation by genetic engineering of cyanobacteria

• Published in: Energy & environmental science Vol. 5; no. 8; pp. 8318 - 8327
• 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: 01.07.2012
• Subjects: Cyanobacteria
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c2ee21124f

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