Fourier transform infrared spectroscopy (FTIR) 
In order to recognize the surface functional molecules involved in biosorption of As (V), FTIR spectra of normal and As treated bacteria was studied. Infra-Red spectra of Bacillus mycoides NR-5 (control) reveals three short peaks at 3588.8, 3277.9 and 2923.7 cm-1 (wave number) representing presence of alcohol and alkyl groups. Arsenic biosorption on the cell surface results in a a single broad and strong peak at 3379.0 Cm-1corresponding to amine and indicated interaction of surface protein-metal complex. In zone 5, two peaks at 1654.0 Cm-1 and 1541 Cm-1 attributed to the amide (I and II) bands were shifted to 1652.9 and 1541.0 Cm-1 strengthening the possibility of metal interaction with surface proteins (Figure 6 a & b).