Multi-metal resistance and potential of Alcaligenes sp. MMA for the removal of heavy metals

Abstract

Pollution of water bodies is increasing because of toxic metals. In view of this, the present study examines the removal efficiency of heavy metals Cu2+, Cd2+, Cr6+, Ni2+, and Zn2+ by a bacterial strain isolated from River Yamuna. Initially, three strains were isolated, and further examined for the maximum tolerance index. Among the three isolates, strain MMA showed the highest tolerance to the heavy metals and was selected. The biochemical characterization and phylogenetic analysis based on 16S rRNA gene sequencing showed that the strain belonged to the genus Alcaligenes. Metal removal by the strain was observed at 20 mg/L in both individual and multi-metal experimental setup. The highest metal removal within 72 h was observed for Cu2+(88.45%) followed by Ni2+(82.45%), Zn2+ (69.99%), Cd2+ (63.04%), and least for Cr6+ (48.93%). Bacterial biosorption studies were done using SEM–EDX and FT-IR. Along with the metal removal, the heavy metal assessment of the River was also done for the year September 2017–August 2018, representing the post-monsoon, monsoon, and pre-monsoon. Cu2+, Cd2+, Cr6+, and Zn2+ were detected in the water sample due to the uncontrolled discharge of effluents into the river.