Insight into the Influencing Mechanism of Endophytic Bacteria on the Adsorption of Heavy Metals by Plants: A Review

Abstract

The research of endophytic bacteria (EB) has attracted increased attention, especially where its application provides a new and effective solution for heavy metals (HMs) polluted control in soil. Therefore, the investigation of endophytes has boomed in hopes of insight into their deeper and complex mechanisms in the phytore-mediation process. Endophytes can not only facilitate plants’ growing and developing, but also promote the enrichment of heavy metals, so as to achieve the goal of environmental restoration. This paper summarizes the research achievements about endophytes in recent years from the following aspects: the discovery and application of endophytes, effects of endophytes on plant growth, heavy metal absorption promoted by endophytes in plants. The study found that endophytes can perfectly symbiosis with plants. Endophytes promote the growth and tolerance to heavy metals of plants by secreting IAA, 1-aminocyclopropane-1 carboxylic deaminase (ACC deaminase), iron carrier, biosurfactant and low molecular weight organic acids. There were other studies that showing that endophytes can enhance the resistance of host plants in adverse environments such as drought resistance, heat resistance and disease resistance. Future application prospects and development direction of endophytes in plants are also discussed in detail. Such as (1) endophytes can help plants resist pests and diseases reflected in the competition with pathogenic bacteria for niche and nutrients to prevent the invasion and reproduction of pathogenic bacteria. (2) Some metabolites produced by endophytic bacteria can be used in medicine. (3) endophytes can effectively reduce the harmful substances accumulated in plants, and the toxic effect of pollutants on plants and enable plants to repair themselves.