Effect of metal-tolerant and plant growth promoting bacteria on Vigna mungo growth and metal accumulation (remediation) efficiency in metal-polluted soil: An in-vitro study

Abstract

Heavy metal pollution has become a major environmental concern in recent years, and its contamination of edible crops and yield is another major factor to consider. As a result, this study was carried out to examine the properties of soil samples collected from farmland near the mining area, as well as metal tolerance and PGP traits of pre-isolated and characterized Pseudomonal aeruginosa. Furthermore, the effect of this P.aeruginosa on growth and metal accumulation (remediation) of/in edible crop Vigna mungo by greenhouse experiment. The physicochemical properties analyses results were beyond the acceptable limits of country standards. Notably, the metal quantities were found to be aluminium, chromium, lead, zinc, and cadmium 14.65 ± 1.58, 92.61 ± 5.19, 342.85 ± 9.52, 393.36 ± 8.23, and 12.29 ± 0.56 mg kg−1 respectively. The P.aeruginosa showed remarkable tolerance to metals such as aluminium, chromium, lead, zinc, and cadmium for up to 250 mg L−1. It also effectively absorbed the metals as follows: aluminium 18.42%, chromium 35.64%, lead 37.85%, and cadmium 26.34%. Interestingly, this P.aeruginosa also possesses significant PDP properties such as ammonia, IAA, siderophore, and solubilize the phosphate as 22.63 μg mL−1, 56.18 μg mL−1, 95.63 μg mL−1, and 634.96 μg mL−1 respectively. This P.aeruginosa showed optimistic effect on growth and metal accumulation (remediation) in V.mungo crop. The V.mungo crop grown without P.aeruginosa showed moderate growth, lower biomass and biomolecule yield, and significant metal accumulation in root and shoot. Hence, the agricultural land surrounding the mining site must be subjected to sustainable remediation approaches in order to correct the farmland soil as free-form pollutants.