This study aimed to evaluate three heavy metal tolerant bacterial strains (HMTB) namely Alcaligenes faecalis MG257493.1, Bacillus cereus MG257494.1 and Alcaligenes faecalis MG966440.1 as antioxidant agents and plant growthpromotorsunderlaboratoryconditions.Theirabilitiestoinhibit2,2-DiPhenyl-2-Picrylhydrazylhydrate (DPPH) as non-enzymatic antioxidant activity and produce plant growth promoters (indole acetic acid (IAA), gibberellins (GA3),salicylic acid (SA),proline (Pro.), sidrophores, exopolysaccharide (EPS) and biosurfactant) wereestimatedinpresenceoffourheavymetalsZinc(Zn2+)cadmium(Cd2+),copper(Cu2+)andlead(Pb2+)at 1000 and 1500mg/l. Results showed that the antioxidant activities of three strains were increased with the increasing of heavy metals concentration. All tested strains were able to produce all estimated plant growth promotersinthepresenceorabsenceofheavymetalsandthehighestamountsofallcompoundswererecorded in media free of heavy metals and decreased with the increasing of heavy metals concentration. Also, results proved that the three evaluated strains were considered as heavy metal tolerant-plant growth promoting bacteria (HMT-PGPB) and have beneficial characteristics for remediating the contaminated mine tailing soil. |
