Minimum Inhibitory Concentration (MIC) and Multi-metal screening
A total of 16 bacteria showed arsenic tolerance in preliminary examination were further evaluated for their minimum inhibitory concentration (MIC) level by spot inoculation of 100 µl of 108 cells/ml bacterial suspension on nutrient agar plates amended with sodium arsenate up to 1500 ppm and sodium arsenite solution up to 500 ppm separately, through pour plate method following incubation at 35°C (Dey et al. 2016). Comparative MIC value of 16 bacterial isolates for other heavy metals like Cadmium (Cd), Cobalt (Co), Copper (Cu), Chromium (Cr), Lead (Pb), Nickle (Ni), and Zinc (Zn) using respective salts was also determined. Based on high arsenic tolerance among 16 bacterial isolates NR5 was selected for further studies.