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Characterization of rhizospheric bacteria of the surrounding soil of a lead [Pb] recycling plant

Abstract:

The aim of this research was to isolate and characterize rhizosphere bacteria of huizache (Acacia farneciana) and mesquite (Prosopis glandulosa), predominant vegetation surrounding a lead (Pb) recycling company. Bacteria were evaluated on their tolerance to Pb(NO3)2, and their capacity to produce indole-acetic acid (IAA) and siderophores using Salkowski and chrome azurol S (CAS) agar medium techniques, respectively. The bacterial isolates were identified through the 16S rRNA gene. Ten bacterial strains tolerated concentrations between 0.6 and 1.8 mM of Pb (NO3)2, of which seven strains had IAA production of up to 60 µg/mL and five strains showed siderophore production. Qualitatively, the bacterial strains L2, L48 and L67 presented a more intense orange halo than the bacterial strains L138 and L23, which indicates a positive reaction of siderophores production. Additionally, the siderophores production of the hydroxamate type produced by the bacterial strains L2, L48, L67, L138 and L23 was variable, between 0.02 and 0.054 µg/mL. The results of this research allow concluding that there are bacterial strains around the lead (Pb) recycling company with a high potential for phytoremediation processes.