好氧甲烷氧化菌温室气体资源化合成聚羟基丁酸酯工艺与调控策略

Municipal waste is an important emission source of methane, which is the second most prevalent greenhouse gas. The capture, development and utilization of methane are the best option for reducing greenhouse gases, improving the environment and achieving sustainable development. Aerobic methanotrophs can activate methane at normal temperature and pressure, then directly synthesize biodegradable bioplastic-polyhydroxybutyrate (PHB), which enables huge economic, environmental and social benefits, and meets the strategic demands of the 13th national five-year plan for ecological environment protection and low-carbon economic development. However, PHB production from methane faces the grate challenges including a lack of high efficient methanotroph, limitation of gas-liquid mass transfer of methane and oxygen, and low-quality PHB difficult to be processed. This project proposes a high-throughput screening technology for directional enrichment and selection of methane oxidizing bacteria to obtain high efficient methanotrophs for PHB production. And then, this project will apply bubbleless membrane aeration to overcome the limitation of mass transfer of methane and oxygen, optimize the design of membrane modules and reactors and develop high-density culture strategy to establish an efficient PHB synthesis process to reduce production costs. Finally, the mechanisms of high molecular weight PHB production and PHB copolymer synthesis will be investigated to develop controlling strategies for high-quality PHB synthesis, which could improve the processing performance and broaden the application scope of PHB. This work will achieve resource recovery from greenhouse gas, and make positive contribution to address the shortage of resources, greenhouse effect and environmental pollution.

城镇废弃物是全球第二大温室气体—甲烷的重要排放源，甲烷的捕集、开发和利用成为削减温室气体、改善环境、实现可持续发展的理想选择。甲烷氧化菌可在常温常压下将甲烷活化，直接合成可降解生物塑料—聚羟基丁酸酯（PHB），具有巨大的经济、环境和社会效益，符合国家“十三五”生态环境保护和低碳经济发展的战略需求。针对高效甲烷氧化菌菌种缺乏、甲烷和氧气气液传质速率低和PHB品质低导致加工难度大等瓶颈问题，本课题拟通过高通量筛选技术对甲烷氧化菌进行定向富集和选育，获得高效PHB合成菌种；采用无泡膜曝气突破甲烷和氧气的气液传质阻力，优化膜组件和反应器设计，建立甲烷氧化菌高密度培养策略，构建高效PHB合成工艺，降低生产成本；揭示高分子量PHB生产及其共聚物合成规律，建立高品质PHB合成与调控策略，改善其加工性能，拓宽应用范围，实现温室气体资源化利用，为有效解决资源短缺、温室效应、环境污染等问题做出积极贡献。

聚羟基烷酸酯是具有生物降解性，生物相容性且机械性能与传统石油基塑料相当的绿色塑料，PHB是存在最广泛的一种形式。在营养限制条件下，甲烷氧化菌可以直接将甲烷合成PHB。本项目从活性污泥中富集驯化甲烷氧化菌群，探索了甲烷氧化菌群合成PHB的调控策略；分离纯化甲烷氧化菌；以乙烷为碳源富集乙烷氧化菌群；优化膜组件结构，设计高效膜曝气反应器培养甲烷氧化菌。.在不同的甲烷氧气比、氮源的条件下，从活性污泥中定向富集获得甲烷氧化菌群；通过16s rRNA高通量测序分析混合菌群的微生物群落结构，结合不同混合菌群的PHB合成能力，筛选出高效的甲烷氧化菌群。改进了分菌方法，分离纯化甲烷氧化菌，鉴定了PHB含量最高的菌株Pseudacidovorax intermedius PHB。完成了膜材料优选，设计了双膜曝气悬浮生长反应器来富集好氧甲烷氧化菌。探索不同甲烷氧气比、铜离子浓度、盐度、温度、酸碱度、硝酸盐和氨氮等影响因子对筛选出的甲烷氧化菌群的细胞生长和PHB合成的影响，进而优化混合菌群生长和PHB合成条件。.研究探索了不同共底物种类、不同共底物浓度和不同甲醇浓度对筛选出的甲烷氧化菌群合成PHB的强化效果。通过饥饿盛宴模式建立甲烷氧化菌群高密度培养策略，探究在模拟的小型中试中盛宴-饥饿时间比、共底物和硝酸盐对筛选出的甲烷氧化菌群PHB合成的影响，进一步优化反应器控制参数，探索甲烷氧化菌群利用甲烷合成PHB实际应用的潜力。在不同的乙烷氧气比、铜离子浓度的条件下，从活性污泥中定向富集获得乙烷氧化菌群；通过16s rRNA高通量测序分析混合菌群的微生物群落结构。