Abstract
Arbuscular mycorrhizal fungi (AMF) play a pivotal role in alleviating heavy metal stress in plants, yet their influence on the rhizosphere microbiome in contaminated soils remains underexplored. This study investigates the modulation of rhizosphere bacterial communities by AMF inoculation under heavy metal stress. A controlled pot experiment was conducted using maize (Zea mays L.) grown in soil spiked with cadmium (Cd), lead (Pb), and zinc (Zn) at three contamination levels. Treatments included inoculation with a consortium of indigenous AMF species (Rhizophagus irregularis, Funneliformis mosseae, and Claroideoglomus etunicatum) and non-inoculated controls. After 60 days, rhizosphere soil was analyzed for heavy metal bioavailability, AMF colonization, bacterial community structure via 16S rRNA amplicon sequencing, and plant biomass. Results showed that AMF inoculation significantly increased plant biomass by 35–60% and reduced Cd and Pb bioavailability by 25–40%. Bacterial alpha diversity (Shannon index) was higher in AMF-inoculated treatments, and community composition shifted towards taxa associated with metal tolerance and nutrient cycling, including Actinobacteria, Bacteroidetes, and Proteobacteria. Redundancy analysis indicated that AMF inoculation explained 28% of the variation in bacterial community structure. These findings demonstrate that AMF not only enhance plant growth and reduce metal toxicity but also reshape the rhizosphere microbiome towards a more resilient and functional community. This modulation represents a key mechanism for improving phytoremediation and sustainable soil management in heavy metal-contaminated soils.