Abstract: Soil heavy metals contamination has become a worldwide environmental problem, posing great threats to human health and economic development. At present, phytoremediation is recognized as the most cost-effective and reliable remediation technique for heavy metals-contaminated soils. This technique mainly utilizes hyper-accumulator plants to extract and accumulate the contaminants from soil. How to improve the heavy metals resistance of plants and promote the plant growth dominates the phytoremediation efficiency. In this aspect, plant-endophytic bacteria symbiosis has its unique superiority. Endophytic bacteria have positive effects on the plant establishment and survival in heavy metals-contaminated soils via improving plant nutrient uptake, decreasing plant pathogens infection, affecting plant enzyme activities, secreting hormone, siderophores, and other organics, and as a consequence, enhancing the heavy metals accumulation by plants. This paper reviewed the recent studies on the screening and application of heavy metals-resistant endophytic bacteria, elucidated the mechanisms of endophytic bacteria-promoted plant growth, plant heavy metals resistance, and heavy metals translocation from root to shoot, and analyzed the processes and mechanisms of endophytic bacteria-enhanced phytoremediation. The potential applications of endophytic bacteria in phytoremediation of heavy metals-contaminated soils were proposed.

Key words: Denitrifying bacteria, Denitrification activity, Pesticide-contamination, Paddy soil