Characterization of siderophore-producing microorganisms associated to plants from high-Andean heavy metal polluted soil from Callejon de Huaylas (Ancash, Peru)

Endophytic and rhizospheric microorganisms associated with six native plants adapted to heavy metal polluted soil from Punta Olimpica and Chahuapampa, located in CaBeton de Huaylas mountains, were evaluated as potential candidates for technologies to clean polluted ecosystems. It was selected 14 bacteria and 9 fungi strains by their iron and/or aluminum siderophore production trait, where BEP17-Dm showed higher production. According to the 16S rDNA analysis, bacteria belong to Pseudomonas, Bacillus, and Achromobacter genera, whereas by ITS analysis fungi belong to Talaromyces, Hypoxylon, Tolypocladium, and Penicillium. All bacteria strains tolerated lead (2-8 mM) and eigth tolerated cadmium (1-6 mM); also all fungi tolerated lead (9-70 mM) and cadmium (3-10 mM). Two bacteria and six fungi solubilized cadmium carbonate, while eleven bacteria and two fungi solubilized tricalcium phosphate, where P. japonica BEP18-Dm and B. subtilis BRU16-Sr exhibited higher solubilization index. None strains solubilized lead carbonate. BEP18-Dm produced higher concentration of IAA (53.42 mu gml(-1)); while six bacteria and all fungi strains produced a low concentration of auxins. Medicago sativa seedlings inoculated with BEP17-Dm, BEP18-Dm, or BRU16-Sr showed more surviving percentage under in vitro culture in presence of Cd, Pb (0.5-1.0 mM), or Al (2.5-5.0 mM). Finally, it is the first report of siderophore-producing microorganisms from polluted soil of Callejon de Huaylas highlands, interestedly they displayed metabolic properties useful to enhance phytoremediation and biotechnology application.

Automated summary

The study evaluated endophytic and rhizospheric microorganisms associated with six native plants in Peru's CaBeton de Huaylas mountains, showing potential for cleaning polluted ecosystems. Certain bacteria and fungi strains demonstrated capabilities for solubilizing heavy metals and phosphates, positively impacting plant growth and survival.