填埋场覆盖土植被根际细菌代谢调控氯苯的生物降解

Rhizosphere bacterial metabolism of plants growing in landfill cover soil regulates biodegradation of chlorobenzene

摘要:

生活垃圾填埋场中，植被调控根际细菌群落结构和特征代谢是强化氯苯(chlorobenzene, CB)生物降解的关键。为系统解析不同植被对根际细菌群落结构和代谢特征的调控机制，本研究利用生物多样性和代谢组学技术考察了不同植被调控下的覆盖土甲烷(methane, CH₄)氧化和CB降解能力、细菌群落结构和代谢特征差异。结果显示，酸模(Rumex acetosa)根际土壤表现出最强的CH₄氧化和CB降解能力，分别为0.08 g/(kg·h)和1.72×10^–6 g/(L·h)，其次是苋(Amaranthus spinosus L.)，构树(Broussonetia papyrifera)根际土壤活性最弱。酸模诱导甲基嗜热菌属(Methylocaldum)在根际定殖，并通过根系分泌物如三乙胺、N-甲基苯胺等小分子有机胺促进三羧酸循环和烟碱代谢，从而显著增强菌株活性，提高CH₄和CB降解效率。构树根系分泌的肉桂酸及其衍生物作为自毒素，抑制微生物活性，并加剧盐胁迫对甲烷氧化菌等关键微生物的负面影响。本研究深入剖析了填埋场覆盖层中典型植被对细菌生态功能的调控机制，为植物-微生物联合控制填埋气污染提供了理论依据和实践指导。

Abstract:

The regulation of rhizosphere bacterial community structure and metabolism by plants in municipal solid waste landfills is a key to enhancing the biodegradation of chlorobenzene (CB). In this study, we employed biodiversity and metabolomics methods to systematically analyze the mechanisms of different plant species in regulating the rhizosphere bacterial community structure and metabolic features and then improved the methane (CH₄) oxidation and CB degradation capacity. The results showed that the rhizosphere soil of Rumex acetosa exhibited the highest CH₄ oxidation and CB degradation capacity of 0.08 g/(kg·h) and 1.72×10^-6 g/(L·h), respectively, followed by the rhizosphere soil of Amaranthus spinosus L., with the rhizosphere soil of Broussonetia papyrifera showing the weakest activity. Rumex acetosa promoted the colonization of Methylocaldum in the rhizosphere, and the small-molecule organic amine, such as triethylamine and N-methyl-aniline, secreted from the roots of this plant enhanced the tricarboxylic acid cycle and nicotinamide metabolism, thereby increasing microbial activity and improving CH₄ and CB degradation efficiency. Conversely, cinnamic acid and its derivatives secreted by Broussonetia papyrifera acted as autotoxins, inhibiting microbial activity and exacerbating the negative effects of salt stress on key microbes such as methanotrophs. This study probed into the mechanisms of typical plants growing in landfill cover soil in regulating bacterial ecological functions, offering theoretical support and practical guidance for the plant-microbe joint control of landfill gas pollution.