植物内生细菌修复重金属污染土壤作用机制研究进展

Mechanism of Endophytic Bacteria Remediating Heavy Metal-Contaminated Soil

内生细菌生活在植物组织内部,长期以来与宿主植物形成了紧密的共生关系。内生细菌在重金属吸收、耐受和解毒方面具有优良的特性,为修复重金属污染土壤提供了有效的新方案。综述了内生细菌强化植物修复重金属污染土壤的作用机制,包括内生细菌通过产生植物生长调节激素,分泌ACC脱氨酶和几丁质酶等,促进宿主植物在重金属胁迫条件下的生长;通过改变重金属的生物有效性/毒性,减轻植物重金属毒害;通过与植物形成联合修复体,加强植物抗重金属毒性的能力。分析了近几年超富集植物内生细菌多样性及其影响因素,探讨了联合修复过程中影响内生细菌强化修复效果的主要因素,包括内生细菌的来源、活性和环境胁迫等各种生物因素和非生物因素,并对内生细菌与植物联合修复的研究方向进行展望,涉及内生细菌自身存活原因和如何耐受重金属的机制研究,植物内生细菌的行为动力学和代谢,以及内生细菌、植物及土壤之间的生态互作效应等,以期推动内生细菌大规模应用于植物修复重金属污染土壤。

Endophytic bacteria reside within plant hosts and have a close symbiotic association with host plants. Their excellent propertiesin heavy metal absorption,tolerance and detoxification provide a novel approach for the remediation of contaminated soil by heavy metals.This review concentrates on the fundamental mechanism of endophyte-assisted phytoremediation of heavy metal-contaminated soils,includingthe promoting the growth of host plants under heavy metals by producing plant growth regulating hormone and secreting ACC deaminases andchitinase and so on,reducing the damages of heavy metals to plants by altering the bioavailability/or toxicity of heavy metal,and improving theresistance of plants to heavy metal stress by forming joint remediating complex. Then recent progress in characterizing the diversity of endophyticbacteria from hyperaccumulator and its influencing factors are also reviewed. Furthermore,the main factors influencing the effect of endophyticbacteria in the phytoremediation are discussed,including the source and activity of endophytic bacteria and various biotic and abiotic factorsof environmental stress. Special attention is paid to the future study in the field of endophyte-assisted phytoremediation technology,such asthe mechanism of endophytic bacteria’s own survival and how to tolerate heavy metals,behavioral dynamics and metabolism of endophyticbacteria,and the ecological interaction between endophytic bacteria,plants and soil will be considered,aiming at promoting the large-scaleapplication of endophytic bacteria in the phytoremediation of heavy metal-contaminated soil.