Effects of artificial humic acid on rhizosphere ecology and microbial regulation in a ryegrass-Bacillus cereus symbiotic system for remediating Cr(VI)-contaminated soil

. Simultaneously, the total Cr content in plants increased by 37.2 %, indicating enhanced hyperaccumulation capacity in ryegrass. A-HA promoted the enrichment of functional microbial communities associated with heavy metal resistance, such as Proteobacteria and Firmicutes, reflecting an optimized soil microbial structure. In terms of plant growth, the combined treatment increased ryegrass biomass by up to 790.3 %, root length by 310.0 %, soil organic matter content by 650.12 %, and soil enzyme activity. Additionally, A-HA significantly enhanced the colonization ability of B. cereus Q-0 in both the rhizosphere and endophytic compartments of plants. This study highlights the unique potential of combining A-HA and B. cereus for effective and eco-friendly Cr(VI) remediation, offering a novel strategy to enhance phytoremediation efficiency in contaminated soils.