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In the present study, a lead (Pb)-resistant bacterium, Staphylococcus hominis strain AMB-2 was isolated from Mandoli industrial area, Delhi and selected for heavy metal biosorption considering multiple heavy metal resistance. In the batch experiment, both living and dead biomasses of strain AMB-2 showed biosorption of Pb and cadmium (Cd) in single and binary systems as analyzed through Inductively coupled plasma-optical emission spectrometry.Living biomass exhibited more biosorption of metals than dead biomass in both single and binary systems. However, in the binary system, metals competed for the attachment sites on the bacterial surface, where Pb got more preference over Cd for the same. The underlying mechanism for the biosorption was attachment of the metal ions through functional groups onto the surface of the biomass as revealed by scanning electron microscopeenergy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction. Conclusively, this study displayed an effective biotreatment of Pb and Cd from aqueous medium using a low-cost biosorbent prepared from S. hominis strain AMB-2 considering biosafety of microorganisms and an eco-friendly approach. K E Y W O R D S bacteria, biosorption, cadmium, lead, Staphylococcus

The present study aims to monitor the surface water quality of different regions in Delhi (India). With many physical and chemical properties, all samples had a high load of pollution in which Najafgarh drain (Nd) exhibited maximum and laboratory tap water (Ltw) minimum contamination. Water samples contained notable amounts of heavy metals including Cr, Cd, As, Cu, Pb and Hg. A total of 88 Hg-resistant bacteria were isolated from all the regions except Ltw. Among all the samples, the density of Hg-resistant bacteria was highest in sample of Nd and their morphotype heterogeneity was highest in sample collected from river Yamuna nearby Kashmiri gate (Kg). Different strains showed different patterns of resistance to different heavy metals and antibiotics. Multiple antibiotic resistance (MAR) indices were high in two samples, the highest reported in a sample taken from river Yamuna nearby Majnu ka tila (Mkt) (0.34). The 12.5% and 24.45% isolates showed β- and α-hemolytic natures, respectively that might be of pathogenic concern. In this account, high concentrations of heavy metals and their resistant bacteria in surface water have severely damaged the quality of water and their resources and produced high risk to the associated life forms.