细胞-纳米组装体的构筑及其对CO2捕获与原位碳转化

Some key non-photosynthetic carbon-fixation microorganism can selectively and gently capture carbon dioxide from the industry waste gas such as flue gas without light irradiation, which proposes a wide application prospect. By now, the study of these bacteria focused on genetic engineering and metabolic pathway modification, however, seldom literature reports capture and transfer efficiency of carbon dioxide. This project plans to create a microorganism-nano assembly, which will be used for carbon dioxide fixation and in situ conversion into platform chemicals.The transfer and conversion processes are enhanced through micro-nano-scale and cell structure. According to our previous progresses on these bacteria, uniform size-controlled adsorptive nanomaterial and magnetic nanomaterial will be synthesized and well assembled with non-photosynthetic carbon-fixation microorganism such as strain Actinobacillus succinogenes ATCC 55618. Thus, the fabrication and regulation of single cell-nano assembly will be realized. Carbon dioxide capture efficiency can be improved dramatically by enhancing the transfer of carbon dioxide between gas phase and cytoplasm by adsorption process. Via optimization of nano-synthetic process and surface modification, assembly between porous nanoparticles and microorganism cells can be fabricated and regulated functionally. The assembly will integrate the advantages of two processes, carbon dioxide sequestration by cells and carbon dioxide adsorption by chemical reagents. Moreover, kinetics will be allocated among nanomaterial adsorption, bio-capture and carbon conversion processes. If this project shall be supported fortunately, carbon dioxide abatement will be established to control the greenhouse effect and to provide a key basic study for carbon dioxide sequestration and carbon resource utilization.

非光合固碳微生物能够在温和无光照条件下特异性地捕获工业废气中CO2，应用前景广阔。迄今提高细胞固碳活性的研究主要集中在基因工程和代谢途径改造，对于CO2捕获与传递效率关注甚少。本项目提出构建一种"微生物-纳米组装体"，从微纳尺度及细胞结构强化CO2的传质与转化，用于CO2固定及原位催化转化为有机平台化合物。以实验室保存的高活性非光合固碳微生物如放线杆菌ATCC55618等为对象，与尺寸均一可控的纳米吸附剂和纳米磁颗粒进行组装，实现单细胞纳米组装体的构筑与调控；利用吸附过程，强化气相中CO2向细胞胞质传递，提高CO2捕获速率；考察多孔纳米颗粒合成和表面改性过程，调控其与细胞的功能组装；通过组装优化纳米吸附剂吸附动力学与生物捕获、碳转化动力学的匹配，将CO2化学吸附和生物固碳的优点相结合。本项目的开展将为温室效应高效控制和碳资源有效利用提供研究基础。

近年来，化石能源利用，森林砍伐，工业化，城市化等人类活动导致大气中二氧化碳浓度逐年上升。温室气体排放导致全球变暖和气候异常已经从一个有争议的话题逐渐成为全世界主流社会的共识，迫切需要开发适宜的二氧化碳减排技术。碳捕获和固定（CCS）技术以及二氧化碳利用技术成为研究的热点。二氧化碳捕获技术包括了地质和海洋的存储，化学、物理吸附剂的分离，生物固定等。一些微生物能够在没有光照的环境下选择性捕获二氧化碳分子，本课题通过在非光合固碳微生物细胞壁交联纳微尺度吸附剂，实现单细胞纳微颗粒组装；通过吸附过程加快气相二氧化碳分子克服传质阻力到达细胞表面的传递速率，增加生物转化的底物供应，强化生物捕获。将二氧化碳吸附剂捕获和生物固碳相结合，通过细胞原位碳转化解决传统吸附捕获过程选择特异性低的问题，实现边捕获、边转化，二氧化碳固定效率达到71 mmol CO2 /g dry cell （24 h），为新型纳微材料的应用研究提供基础。此外，通过聚合物吸附剂和磁性纳米颗粒的共组装，在提高微生物固碳活性和稳定性的同时，简化分离步骤，实现细胞的快速分离回收和重复使用。本项目在新型纳微吸附颗粒的制备和改性、二氧化碳转化有机酸（丁二酸、乳酸）的生物制造过程强化、纳微颗粒-细胞组装体固碳三个方面取得的显著成果，将为碳资源的高效利用提供了新思路。