Modulation of the efficiency of trace metal phytoremediation by Sedum plumbizincicola by microbial community structure and function

Recent research on the rhizosphere microbiome indicates that plants may benefit more from microbial communities than from individual members in a community. The link between soil microbiome and plant performance remains poorly understood during trace metal phytoremediation by hyperaccumulator plants. The effect of different microbiomes on the cadmium (Cd)/zinc (Zn) phytoextraction efficiency of Sedum plumbizincicola was therefore explored. Different microbiomes were set up using gamma-irradiation and vancomycin addition and a pot experiment was conducted. The microbial communities were characterized using high-throughput sequencing and their functions were predicted. Plant Cd and Zn contents in the vancomycin-amended treatment were about 38-46% and 35%-53% respectively lower than those in the other treatments. Bacterial composition and diversity were substantially changed by gamma-irradiation and vancomycin addition but plant trace metal accumulation did not change subsequently. The bacterial functional profiles were very different following treatment with vancomycin compared with the other treatments at KEGG orthology hierarchy level 3. Genes related to up-regulated biofilm formation and down-regulated siderophore synthesis may partly contribute together to the low plant trace metal accumulation following vancomycin treatment. Specific bacterial community function rather than bacterial community diversity and composition may affect trace metal uptake by hyperaccumulator plants.