蚯蚓的行为模式对果蔬垃圾肥料化过程中氨氧化驱动者的影响机理

The loss of nitrogen in vermicomposting system and the higher content of nitrate in vermicompost from fruit and vegetable wastes affect its application value as a bio-fertilizer. The ammonia oxidation process plays a critical role in regulating nitrogen cycle and retaining fertilizer during vermicomposting process. Hence, this program proposes to reveal the mechanisms regarding the effect of earthworm activity on the ammonia oxidizing drivers in vermicomposting system, with the different behaviors of earthworms as a research object. For this, molecular methods such as FISH, qualitative PCR and PCR-DGGE combined with nitrogen transformation features are employed to analyze the activity, number and community diversity of ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) during vermicomposting of fruit and vegetable wastes by two different ecological types of epigenic and endogenic earthworms, respectively. The aims of present study are (1) to seek a dominant ammonia oxidizing diver from AOA and AOB in vermicomposting system, (2) to separately clarify the effect of gut digestive, burrowing and mucus attractive behaviors of earthworms on the ammonia oxidizing process and its underlying mechanisms and the linkages of different behaviors, (3) to ascertain the difference of earthworms affect the ammonia oxidizing drivers, and (4) to elaborate the ultimate mechanisms of earthworms regulating the nitrification effect during vermi-fertilization process. This project can provide a rationale for the reduction in the loss of nitrogen, the elevation of fertilizer quality and the improvement of vermicomposting mechanisms.

蚯蚓果蔬垃圾堆体中的氮损失和产物蚯蚓粪中过高的硝氮含量影响了其潜在的肥料化价值。氨氧化进程对堆体氮素转化和保肥起着决定性作用。本项目以蚯蚓的不同行为模式为研究对象揭示蚯蚓的活动对果蔬垃圾肥料化过程中氨氧化驱动者的影响和机理。选用两种不同生态位的蚯蚓（表居型和内居型），运用FISH、定量PCR和PCR-DGGE的分子生物学手法，对蚯蚓处理果蔬垃圾过程中的氨氧化菌古菌(AOA)及氨氧化细菌(AOB)的活性、数量和种群进行剖析，并结合氮素理化和生化指标的转化规律，明确蚯蚓堆肥体中主导的氨氧化驱动者，分别揭示蚯蚓的不同行为模式‘肠道消化、机械运动和粘液诱导’对氨氧化进程的影响和机理以及不同行为模式之间的关联，探知不同生态类蚯蚓对氨氧化菌群影响的差异，阐明蚯蚓调控肥料化系统中硝化作用的机理。本项目拟为减少蚯蚓果蔬垃圾肥料化过程氮素的损失和提高产物农用价值，完善蚯蚓堆肥机制提供科学理论的依据。

蚯蚓果蔬垃圾堆体中的氮损失和产物蚯蚓粪中过高的硝氮含量影响了其潜在的肥料化价值。氨氧化进程对堆体氮素转化和保肥起着决定性作用。研究以蚯蚓的不同行为模式‘肠道消化、机械运动和粘液诱导’为目标，揭示蚯蚓的活动对果蔬垃圾肥料化过程中氨氧化驱动者的影响和机理。结果表明：果蔬蚯蚓堆肥硝化作用主要发生在失水后期，并持续至结束。干式蚯蚓堆肥更有利于硝化作用的进行。相比于AOB，AOA是果蔬蚯蚓堆肥体中氨氧化作用的主导者。Nitrospira，Nitrococcus，Nitrosomonas，Nitrosococcus为优势的AOB菌属；Nitrosopumilus，Nitrosocaldus，Nitrosotalea，Nitrososphaera为优势AOA菌属。堆肥体中蚯蚓肠道消化直接降低基质有效C/N，修改微生物保外聚合物中水溶性有机碳氮的特征，改善AOA和AOB的生存环境，是蚯蚓氨氧化的限速步骤。粘液和蚯蚓粪能给AOA与AOB提供营养，特别是可用碳源，改变其种群多样性。生物扰动能增加基质供氧、降低含水率，促使AOA和AOB在堆肥体中均质分布，加速氨氧化进程。因此，当堆肥体中栖息一定数量AOA与AOB后，硝化反应会占主导，堆肥体逐渐腐熟。研究还显示蚯蚓堆肥运行工艺、基质种类、环境污染物对蚯蚓氨氧化进程均有影响。本项目为减少蚯蚓果蔬垃圾肥料化过程氮素的损失和提高产物农用价值，完善蚯蚓堆肥机制提供科学理论的依据。