生活垃圾腐烂释放含硫有机废气与细菌群落的相互作用机制及其细胞毒性效应研究

The release of sulfur organic waste gas during bio-decomposition of household garbage gained increasing concern recently, due to their potential adverse effect on the human health. Therefore, this project will choose the emitted sulfur organic waste gas from household garbage as model compounds to investigate their environmental geochemical transformation mechanisms, the interaction mechanisms between the sulfur organic waste gas with the bacterial community in household garbage, as well as their potential toxicity. Based on our and other researchers’ previous works, the evolution as well as stress response of the bacterial community will be investigated during the whole bio-decomposition process of household garbage. Furthermore, the mechanisms of the decline or development of typical bacterial strains in the community will be revealed from the aspect of the toxic effects of sulfur organic waste gas to the bacteria or the metabolic transformation of them by the typical bacterial strains. Particularly, the interdependent relationship between microbial community structure and sulfur organic waste gas emission will be established. Furthermore, to provide conditions similar to those present in naturally occurring cells in the respiratory tract, the toxic effects of the sulfur organic waste gas exposure of human epithelial lung cells will be conducted in vitro using a Cultex® system and air-liquid interface cell culture exposure method. The cell damage, induced oxidative stress, and proinflammatory response during this process will be investigated in detail. Finally, deeper relationship between stress response of recessive bacterial strain in the bacterial community in household garbage and cytotoxicity from the sulfur organic waste gas will be dug up. The success of the project will provide a fundamental knowledge for source, transportation, transformation, environmental fate of atmospheric sulfur organic waste gas emitted during the bio-decomposition of household garbage, as well as emission minimizing and reduction of human health risk.

生活垃圾在微生物作用下能够释放大量的含硫有机废气严重危害人体健康。本项目在前人和我们的研究基础上，拟以典型的生活垃圾排放含硫有机废气为研究对象，重点探讨垃圾腐烂的全生命周期中细菌群落的结构与演替规律及其对细菌群落的影响与应激机制，揭示含硫有机废气对细菌群落的致毒或代谢解毒机制影响其衰亡或增殖的机制，建立垃圾腐烂过程中细菌群落变化特征与释放含硫有机废气的组成与浓度之间的相互关系。进一步通过细胞气液界面暴露实验，重点开展典型含硫有机废气对人体呼吸系统细胞的毒性效应与机制研究，并通过细胞损伤、诱导氧化应激及其细胞炎化因子(包括基因表达)的检测，发掘细菌群落中衰亡细菌产生氧化应激和细胞毒性之间的相关关系，更真实地揭示生活垃圾腐烂产生的含硫有机废气通过呼吸暴露对人体健康的潜在危害。项目的成功实施可为生活垃圾腐烂释放的含硫有机废气的来源、迁移转化、环境归趋及其人体健康风险消减提供翔实的理论和实验依据。

生活垃圾在微生物作用下能够释放大量的含硫、含氮恶臭有机废气严重危害人体健康。本项目以典型的生活垃圾为研究对象，重点开展了以下内容：.（1）蔬菜（洋葱、豆瓣菜和辣椒）腐败时检测到37、40和28种VOCs。鱼腐败时释放48种VOCs，鸡肉和猪肉释放41种VOCs。肉类中对恶臭气味贡献最大的是鱼肉，蔬菜中释放恶臭气味最多的是豆瓣菜。在混合水果，混合蔬菜和混合肉类垃圾分解时，分别检测到41，39和38种VOCs，其中OVOCs和VOSCs最丰富。微生物群落结构随发酵时间而变化。在整个分解过程中，水果中乳酸菌的含量很高，而混合蔬菜中不动杆菌的含量增加，并且具有硫代谢能力。然而，随着混合肉类垃圾的分解时间增加，优势属也有变化。总之，不同食物垃圾分解之间的VOC排放特征与细菌群落之间存在显著差异和相关性。.（2）开展了典型含氮恶臭污染物暴露对人体呼吸系统的毒性作用研究。.发现甲胺的刺激浓度对16HBE的细胞毒性有显著影响，甲胺浓度越高，对应的细胞毒性越大，细胞膜的破损越严重，细胞活力越低，且呈现一定的剂量依赖性。甲胺能影响细胞因子相关的基因表达，特别是会影响与细胞增殖和凋亡相关基因过表达，即可以导致细胞死亡及诱导肿瘤发生。.三甲胺诱导的16HBE细胞活力以浓度依赖性方式降低，而细胞内ROSs的产生以浓度依赖性方式增加。暴露会导致细胞内氧化还原系统的紊乱，并进一步诱导了细胞因子IL-6的大量分泌，进而促进炎症反应的产生，最终导致细胞膜破损以及细胞坏死。机理研究发现二甲胺是三甲胺的主要的代谢产物，并进一步代谢为甲胺。这些代谢物均比三甲胺毒性更高，表明这些代谢产物与有机胺母体化合物一起可能共同诱导细胞内的毒性效应。.（3）开展了典型含硫恶臭污染物甲硫醇暴露对人体呼吸系统的毒性作用研究。发现暴露下甲硫醇的暴露会引起16HBE细胞活力的下降以及细胞膜破裂现象的出现。甲硫醇通过诱导16HBE细胞产生ROS，进一步激活细胞内的TNF信号通路，激活RIPK1和RIPK3坏死小体，使得细胞内线粒体膜电位下降，最后导致细胞的坏死。机理研究发现甲硫醚是甲硫醇在16HBE细胞中的主要代谢产物，他们对细胞具有一定协同致毒效应。.本项目的顺利实施可为生活垃圾腐烂释放的含硫、含氮有机废气的来源、迁移转化、环境归趋及其人体健康风险消减提供翔实的理论和实验依据。