Genomic and Functional Characterization of Priestia megaterium MOD5IV isolated from the rhizosphere of Caesalina spinosa (Mol.): Enhancing Phytoremediation Potential in Multi-Metal Contaminated Soils
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Heavy metal contamination poses a global threat due to its widespread occurrence and the high toxicity of these elements. Among various methods, phytoremediation has emerged as a preferred approach for the bioremediation of heavy metal-contaminated soils. The search for microorganisms facilitating phytoremediation has become critical to advance ecosystem remediation efforts. Plant growth-promoting bacteria (PGPB) have garnered significant attention in recent decades. In this context, the strain MOD5IV was isolated from the rhizosphere of a Caesalpinia spinosa plant thriving on mining waste in Andacollo, Chile. This strain was initially selected for its plant growth-promoting properties.
This study comprehensively analyzed this strain’s functional and genomic characteristics. MOD5IV exhibited notable PGPB features, including phosphate and potassium solubilization, nitrogen fixation, phytohormone production, and growth promotion of Arabidopsis thaliana . Genomic analysis revealed a chromosome size of 5,254,635 bp and nine distinct plasmids hosting over six thousand genes. Phylogenetic analysis classified the strain within the species Priestia megaterium . Functional annotation identified 16 genes associated with tolerance to metals and metalloids, including arsenic ( arsB / arsC ) and copper ( copC / copD ), as well as genes conferring resistance to cadmium, lead, mercury, zinc, and cobalt. Accordingly, this strain exhibited robust tolerance to multiple metals, notably copper, arsenic, chromium, cadmium, and lead. Regarding its PGPB capabilities, MOD5IV possesses genes related to siderophore production, nutrient solubilization, IAA synthesis, and nitrogen fixation. Furthermore, MOD5IV promotes the growth of C. spinosa grown on tailings in laboratory experiments, increasing its capacity to accumulate copper. Overall, Priestia megaterium MOD5IV exhibits promising traits for microbe-assisted phytoremediation of metal-contaminated soils.
IMPORTANCE
This study explored native metal multi-resistant bacteria for bioremediation of contaminated soils, supporting the phytoremediation perspective. We characterized a novel rhizospheric Priestia megaterium strain at both functional and genomic levels. This strain was isolated from mine waste material in a locality within the arid regions of South America—a geographical area not previously reported for this taxon. These findings may provide new insights into the biogeographical distribution of P. megaterium and its associated genetic determinants. Additionally, the study underlines the strain’s diverse metabolic capabilities, reinforcing its suitability as a model for developing microbe-assisted phytoremediation processes of metal-contaminated soils, increasing the evidence of the Atacama desert as source of microbiological solutions for climate adaptation and environmental remediation.
