Lead tolerance and siderophore production by native Pseudomonas spp. isolated from lead-contaminated environments in Colombia.

Siderophores are organic compounds known for their chelating properties and specific biochemical characteristics, with potential applications in biotechnology, especially in bioremediation. This study evaluated lead tolerance and pyoverdine-type siderophore production in native Pseudomonas spp. isolates from lead-contaminated water. Lead tolerance was assessed using different lead concentrations (5, 10, 25, 50 mg/L) through the minimum inhibitory concentration. Siderophore production was estimated based on the percentage of siderophore units (PSU) in the presence and absence of lead. Among the 14 strains analyzed, 11 operational taxonomic units (OTUs) were identified. Four Pseudomonas spp. strains (P07, P35, P36, and P38) were tolerant to lead concentrations higher than 25 mg/L. Although pyoverdine production was detected in P07, P10, P11, P16, P25, P35, and P38 strains, no synthesis of catecholate or hydroxamate was detected. The P07 strain was the highest siderophore producer with a PSU of 90 ± 8.5%. Lead concentration above 600 ppm reduced the PSU by up to 34%. This study demonstrates that native strains of Pseudomonas isolated from lead-contaminated extreme environments can tolerate lead while producing bioactive metabolites, such as pyoverdine-type siderophores.