Evaluation of interaction among indigenous rhizobacteria and Vigna unguiculata on remediation of metal-containing abandoned magnesite mine tailing.

Abstract

Abandoned magnesite mine heap causing pollution to nearby farmland and water reservoir. Thus the intention of this research was to screening metal mobilizing and absorbing bacteria from the rhizosphere section of V. unguiculata from farmland nearby to magnesite mine. Further, studied their stimulus effect on growth, biomass, and phytoextraction prospective of V unguiculata in mine tailing. The results of the physicochemical properties of mine tailing shows that four metals (Pb, Mn, Cd, and Zn) were crossing the permissible limit. Out of 27 isolates, 2 isolates (MMS15 and MMS17) were identified with maximum metal tolerance for up to 700mgL-1 (MIC) and metal mobilization (Pb 5.5 and 5.87, Mn 6.6 and 4.88, Cd 1.99 and 2.59, and Zn 6.55 and 6.94mgkg-1) and biosorption efficiency as Pb 3.74 and 3.74, Mn 4.9 and 4.7, Cd 2.41 and 3.96, and Zn 4.3 and 4.9mgg-1. These two strains were identified as members of B. cereus and Kosakonia sp. using 16S rRNA technique and labelled strains NDRMN001 and MGR1, respectively. The Kosakonia sp. MGR1 effectively fixes the nitrogen in the rate of 81.94% and B. cereus NDRMN001 solubilizes 69.98 ± 2.31mgL-1 of soluble phosphate. The experimental group's study results show that the group C (Kosakonia sp. MGR1 and B. cereus NDRMN001) has effectively stimulate the growth, biomass, and phytoextraction potential of V. unguiculata. The results conclude that the optimistic interaction between these two bacteria could be more significant to minimize the metal pollution in magnesite mine tailing.