Synthetic physical contact-remodeled rhizosphere microbiome for enhanced phytoremediation

Phytoremediation is a prevalent strategy to treat environmental pollution caused by heavy metals and eutrophication-related pollutants. Although rhizosphere microbiome is critical for phytoremediation, it remains a great challenge to artificially remodel rhizosphere microbiome for enhancing multiple pollutant treatment. In this study, we designed a synthetic bacterium to strengthen physical contact between natural microbes and plant roots for remodeling the Eichhornia crassipes rhizosphere microbiome during phytoremediation. The synthetic bacterium EcCMC was constructed by introducing a surface-displayed synthetic protein CMC composed of two glucan-binding domains separated by the sequence of the fluorescent protein mCherry. This synthetic bacterium strongly bound glucans and recruited natural glucan-producing bacterial and fungal cells. Microbiome and metabolomic analysis revealed that EcCMC remarkably remodeled rhizosphere microbiome and increased stress response-related metabolites, leading to the increased activity of antioxidant enzymes involved in stress resistance. The remodeled microbiome further promoted plant growth, and enhanced accumulation of multiple pollutants into the plants, with the removal efficiency of the heavy metal cadmium, total organic matters, total nitrogen, total potassium, and total phosphorus reaching up to 98%, 80%, 97%, 93%, and 90%, respectively. This study sheds a novel light on remodeling of rhizosphere microbiome for enhanced phytoremediation of water and soil systems.