Genomic and functional insights on Priestia megaterium MOD5IV: enhancing metal phytoremediation potential in arid environments.

Metal contamination poses a global threat due to its widespread occurrence and high toxicity. Phytoremediation constitutes a preferred, environmentally rational approach for soil bioremediation. The identification and characterization of facilitating microorganisms, especially plant growth-promoting (PGP) bacteria, is essential. This research aimed to characterize in depth a novel Priestia megaterium strain isolated from multimetal-contaminated soils in the Atacama Desert, demonstrating strong potential for microbe-assisted phytoremediation. MOD5IV strain exhibited significant PGP traits: phosphate/potassium solubilization, siderophore production, nitrogen fixation, phytohormone production, and robust growth promotion of Arabidopsis thaliana. Genomic analysis (5.25 Mbp chromosome, nine plasmids) revealed over 6000 genes. Functional annotation confirmed its dual capacity, identifying operons for resistance to copper, cadmium, lead, mercury, zinc, and cobalt, along with PGP-linked genes. Consistently, MOD5IV exhibited high multi-metal tolerance and significantly enhanced the phytoremediation potential of Caesalpinia spinosa in laboratory trials. MOD5IV is a novel native isolate from the extreme Atacama Desert, with an integrated genomic and functional profile that positions it as a highly promising bioinoculant. Its robust multi-metal resistance and high PGP capacity are specifically adapted to counteract the synergistic stresses of aridity and multimetallic toxicity, characteristic of rigorous field conditions.