Engineered Escherichia coli with Periplasmic Carbonic Anhydrase as a Biocatalyst for CO2 Sequestration
Engineered Escherichia coli with Periplasmic Carbonic Anhydrase as a Biocatalyst for CO2 Sequestration
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DOI：
10.1128/aem.02400-13
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发表时间：
2013-11-01
影响因子：
4.4
通讯作者：
Cha, Hyung Joon
中科院分区：
文献类型：
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作者：
Jo, Byung Hoon;Kim, Im Gyu;Cha, Hyung Joon
碳酸酐酶是一种可逆催化二氧化碳水化的酶。最近有人提出，这种速度非常快的酶可用于隔离二氧化碳，这是一种主要的温室气体，使其成为化学二氧化碳减排的有希望的替代方案。为了促进酶的经济使用，我们在大肠杆菌的周质中设计了淋病奈瑟菌（ngCA）的碳酸酐酶，从而制造了细菌全细胞催化剂。然后，我们研究了该系统在矿物碳酸化封存二氧化碳中的应用，这一过程具有储存大量二氧化碳的潜力。ngCA以可溶性形式在大肠杆菌的周质中高度表达，与细胞质ngCA和先前报道的全细胞CA系统相比，重组细菌细胞显示出独特的水合物二氧化碳能力。ngCA在大肠杆菌周质中的表达大大加快了碳酸钙（CaCO3）的形成速度，并对较低ph条件下CaCO3的最大生成量产生了显著的影响，同时还表明，周质酶的热稳定性得到了显著提高。这些结果表明，具有外质ngCA的工程细菌细胞可以成功地作为一种有效的CO2固存生物催化剂。
Carbonic anhydrase is an enzyme that reversibly catalyzes the hydration of carbon dioxide (CO2). It has been suggested recently that this remarkably fast enzyme can be used for sequestration of CO2, a major greenhouse gas, making this a promising alternative for chemical CO2 mitigation. To promote the economical use of enzymes, we engineered the carbonic anhydrase from Neisseria gonorrhoeae (ngCA) in the periplasm of Escherichia coli, thereby creating a bacterial whole-cell catalyst. We then investigated the application of this system to CO2 sequestration by mineral carbonation, a process with the potential to store large quantities of CO2. ngCA was highly expressed in the periplasm of E. coli in a soluble form, and the recombinant bacterial cell displayed the distinct ability to hydrate CO2 compared with its cytoplasmic ngCA counterpart and previously reported whole-cell CA systems. The expression of ngCA in the periplasm of E. coli greatly accelerated the rate of calcium carbonate (CaCO3) formation and exerted a striking impact on the maximal amount of CaCO3 produced under conditions of relatively low pH. It was also shown that the thermal stability of the periplasmic enzyme was significantly improved. These results demonstrate that the engineered bacterial cell with periplasmic ngCA can successfully serve as an efficient biocatalyst for CO2 sequestration.