堆肥过化程中氨氧化细菌(AOB)和氨氧化古菌(AOA)对氧浓度变化的响应机制

The composting is one of the efficient ways to reuse the agricultural organic solid wastes and to reduce the environmental pollution. The nitrogen cycle is responsible for cumulation and loss of nitrogen, compost quality, and emission of greenhouse gas nitrous oxide during composting process, and ammonia-oxidizing microorganism play the key roles in this process. Oxygen concentration is one of key factors and responsible for the diversity of microorganism, process of biochemistry, composting efficiency and cost during composting process. The diversity, abundance and activity of Ammonia-oxidizing Bacteria (AOB) and Ammonia-oxidizing Archaea (AOA) has been detected in detail in natural environments, such as marine, freshwater, soils, estuarine sediment, wetland, and so on. However, there were few results of the relevance of AOA, AOB to nitrogen loss, and there were not any results reported about responses of AOB and AOA to different oxygen concentrations during composting process. The aim of the experiment is to detect the diversity and abundance of AOA and AOB, and to analyze the function, activity and contribution of AOA and AOB in ammonia oxidation during microaerobic and aerobic composting process with molecular biological technique, then to detect the responses of AOA and AOB to different oxygen concentrations. Therefore, the experiments will help to understand who is the dominant driver of ammonia oxidation and what does ammonia oxidizing microorganism do during composting process. The relevance of AOA and AOB's activities to nitrogen can be detected, and responses of AOA and AOB to different oxygen concentrations during composting process also will be illuminated. At the same time, results will improve the knowledges about nitrogen cycle in nature, and it can also provide the basic data controlling efficiently nitrogen loss and reducing emission of greenhouse gas during composting process in the future.

堆肥化是农牧业固体废弃物无害化和资源化的主要途径之一。堆肥过程中氮循环决定着氮素的累积和损失，决定着堆肥品质和温室气体排放量，氨氧化菌群驱动的氨氧化作用在其中发挥着重要作用。氧浓度是影响堆肥化过程微生物多样性、生物氧化还原过程、堆肥化效率和成本的重要因素素。AOA和AOB是参与氮循环的重要微生物，在海洋、土壤、河流沉积物、湿地等自然环境中有广泛的研究，但在堆肥这种人工可控环境下，有关堆肥化过程中AOA/AOB对于氧浓度变化的响应机制、AOA/AOB与堆肥过程氮损失关系研究还是空白。本研究利用分子生态学技术，研究不同氧浓度下堆肥化过程中AOA和AOB的多样性、丰度、分布特征，分析AOA和AOB在堆肥化过程中的活性及其在氮循环中的贡献，探讨AOA和AOB对氧浓度变化的响应机制，填补堆肥环境中AOA/AOB对氧浓度变化响应研究的空白，为有效调控堆肥化过程中氮损失和温室气体排放提供理支撑。

堆肥过程中氨氧化菌群驱动的氨氧化作用在氮循环过程其中发挥着重要作用。氧浓度是影响堆肥化过程微生物多样性、生物学过程、堆肥化效率和成本的重要因素。本课题为了研究在堆肥过程中AOA和AOB的活性及其氮循环中的贡献，探讨AOA和AOB对氧浓度变化的响应机制，进行了不同氧浓度下堆肥环境中氨氧化潜力和氮素含量的变化、堆肥环境中AOA和AOB菌群结构组成、堆肥环境中AOA和AOB丰度的变化及AOA/AOB对氧浓度的响应机制的研究。研究以牛粪和草坪草为主要堆肥原料，设置不同通风量处理和变量通风处理两个堆肥实验。.不同通风量处理结果表明，通风显著提高堆体温度和高温持续时间，提高氨氧化潜力；氮素损失与通风量大小呈正相关；通风量显著影响微生物多样性。在各种环境因子中，与细菌菌群结构变化相关性最大的因素是铵态氮，其次是温度；与真菌菌群结构变化相关性最大的因素是通风量，其次是总有机碳。与AOA菌群结构变化相关性最大的因素是通风量，其次是含水率；与AOB菌群结构变化相关性最大的因素是含水率，其次是氧气。AOB amoA基因数量与环境因子铵态氮相关性最大，其次是堆体温度。AOA amoA基因数量与堆体温度相关性最大，其次是铵态氮。在变量通风堆肥化过程中，通风量显著地影响氧气浓度，通风能提高总氮含量，但通风处理间差异不显著；通风能提高氨氧化潜力；氮素损失与通风时间和通风量呈正相关；堆肥前期，由于高温抑制amoA基因数量变化不显著。前期通风后期不通风有利于AOA amoA基因数量增长，适当的通风能提高amoA基因数量。氨氧化潜力与AOA和AOB amoA基因数量呈正相关；氧气是影响AOB amoA基因数量的最显著因素，其次是总氮；硝态氮是影响AOA amoA基因数量的最显著因素，其次是氧气。.这些发现使人们重新认识了AOA在堆肥元素循环中的作用，对于人们认识自然界中AOA、AOB生态分布、生态功能具有一定的指导意义。在实践中，该研究可以为增加堆肥氮素含量，减少氮素损失，提高堆肥品质等提供理论指导。