Rhizosphere Priestia aryabhattai Promotes Manganese Biotransformation and Detoxification in Miscanthus sinensis

Abstract Miscanthus sinensis, a pioneer species in manganese (Mn) tailings, can survive under high Mn stress. However, its rhizosphere microorganisms involved in Mn biotransformation and detoxification remain poorly understood. This study characterized an indigenous strain, Priestia aryabhattai XT78, isolated from the rhizosphere of M. sinensis at in situ Mn tailings. Multi-omics and physiological analyses supported the involvement of both multicopper oxidase-associated oxidation and pH elevation in XT78-mediated Mn(II) oxidation, leading to the formation of lamellar and network-like biogenic Mn oxides. In pot experiments, XT78 inoculation facilitated rhizosphere colonization, decreased soil Mn(II) by 21.3%, increased Mn(III/IV) by 22.7%, and improved soil nutrients. XT78 inoculation was also associated with shifts in microbial community structure and enrichment of taxa (Acidobacteriota, Gemmatimonadota, and Firmicutes) associated with metal resistance, Mn oxidation, and biofilm formation. These changes were accompanied by improved plant growth, including increased biomass and chlorophyll content, enhanced root development through indole-acetamide pathway-associated indole-3-acetic acid synthesis, and reduced Mn translocation. These findings highlight the potential of P. aryabhattai as an indigenous multifunctional inoculant for Mn biotransformation, rhizosphere detoxification, and tailings bioremediation.