Survival strategies and dominant phylotypes of maize-rhizosphere microorganisms under metal(loid)s contamination

Profound understanding of metabolic capabilities of microorganisms is prerequisite for effective bioremediation. However, microorganisms in neutral-alkaline soils affected by metal(loid)s contamination around mining area remains under-studied. Herein, microbial community and survival strategies of microorganisms in rhizospheric soils highly contaminated by multiple metal(loid)s (such as lead (Pb), zinc (Zn), cadmium (Cd), arsenic (As), and antimony (Sb)) from a carbonate-hosted Pb—Zn deposit in South China were profiled via 16S ribosomal RNA (rRNA) gene sequence and shotgun metagenomic analysis. The results indicated that enriched levels of toxic metal(loid)s had significant impacts on the diversity and abundance of rhizosphere microorganisms. The siderophores produced by Sphingomonas might enhance maize uptake of toxic metal(loid)s. Variovorax and Terrimonas may be potential remediation microorganisms for metal(loid)s contamination. Shotgun metagenomics indicated that metal(loid)s related genes (such as zntA and arsC) may enhance the tolerance of rhizosphere microorganisms to toxic metal(loid)s. The lack of arsenite oxidase gene (aoxAB) may inhibit the biogeochemical cycle of As in the studied area. The findings are critical for facilitating microbiome bioremediation for soil affected by neutral-alkaline mining.