Synergistic role of PGPR and fungal isolates in mitigating As and Pb stress and promoting growth of Arachis hypogaea L.

Abstract

Heavy metals, also known as toxic metals, are major environmental pollutants that adversely impact all forms of life, disturbing soil ecology and reducing agricultural productivity. Certain indigenous microbes possess remarkable tolerance to these metals and play a vital role in restoring contaminated soils. In the present study, plant growth-promoting rhizobacteria and fungi were isolated from the rhizosphere and evaluated for their metal tolerance potential. Among the bacterial isolates (Pseudomonas alcaliphila PAS1, Pseudomonas aeruginosa PAS2, Pseudomonas toyotomiensis PTS3, Bacillus subtilis BSS1) expressing resistance to arsenic and lead which observed up to concentrations of 100–1200 ppm on nutrient agar. The fungal isolate Aspergillus japonicus (AJ01) exhibited tolerance up to 200 ppm of Pb and 500 ppm of As. Pot culture experiments were using Arachis hypogaea grown under As and Pb stresses with treatments of PGPR, PGPF, Compost and chemical control. Pseudomonas alcaliphila PAS1 was significantly enhanced plant growth by 100% and Pseudomonas aeruginosa PAS2 by 60% in contaminated soil, indicating strong tolerance and growth-promoting potential. Pseudomonas alcaliphila PAS1 increased chlorophyll content by 92.3% under As stress as compared to the control, while Pseudomonas toyotomiensis PTS3 showed a 70% increased, demonstrating high metal tolerance. In contrast, As and Pb stressed plants showed adverse effects. These findings highlighted the potential of selected PGPR and fungi as eco-friendly alternatives for the remediation and recovery of heavy metal-contaminated soils in Arachis hypogaea cultivation.