Identification of Escherichia Coli and Heavy Metal Resistant Genes (czcA, czcD and merA) in Cd and Pb ContaminatedSurface Water from District Jhal Magsi, Balochistan

Abstract

This study aimed to detect the concentrations of heavy metals and heavy metal resistance genes (HMRGs) in Escherichia coli (E. coli) isolated from running and standing surface drinking water of Jhal Magsi district, Balochistan. Heavy metal concentrations were determined using a flame atomic absorption spectrophotometer and identification of E.coli and heavy metal resistant genes were performed by Polymerase Chain Reaction (PCR). The concentrations of Cd and Pb ranged from 0.058±0.001 to 0.98±0.0003 mg/L and 1.01±0.0011 to 2.03±0.01155 mg/L, respectively in running water and in standing water it ranged from 0.098±0.001 to 0.23±0.0003 and 1.11±0.0011 to 2.97±0.0011 mg/L, respectively. The results showed that the concentration of Cd and Pb exceeded WHO and EPA safe limits. Out of 60 water samples, 39 positive samples of E.coli were confirmed through cultural, microscopic, biochemical and molecular techniques. All E. coli isolates were examined for the heavy metal-resistant genes and percentages of czcA, czcD, and merA were recorded at 21/39 (32.81%), 23/39 (35.9%), and 20/39 (31.25%), respectively. It has been concluded that surface water is more contaminated with Cd and Pb as compared to groundwater, which played an important role in the development of HMRG in E. coli.