The influence of heavy metals toxicity on the antioxidant enzyme activities of resistant E. coli strains isolated from waste water sites

Heavy metals are toxic because they interfere with the normal biochemical reactions of the human body. The release of heavy metals into the environment causes an environmental pollution problem because they are nonbiodegradable and hence accumulate in living organisms. Heavy metals, H2O2 and other pollutants increase the production of reactive oxygen species (ROS) such as O2 , OH , H2O2 (Abassi, 1998). The importance of antioxidant enzymes is generally emphasized in preventing oxidative stresses by scavenging ROS or reduction of oxidized glutathione to reduced form (Lenártová et al., 1998). Superoxide radicals (O2 ) generated is converted to H2O2 by the action of Superoxide dismutase (SOD). The accumulation of H2O2 is prevented in the cell by Catalase (CAT), Peroxidase (POX) or by the ascorbate glutathione cycle where Ascorbate Peroxidase (APOX) reduces it to H2O (Harinasut, 2003). Glutathione reductase is produced by Streptococcus bovis and ISSN: 2319-7706 Volume 2 Number 12 (2013) pp. 162-175 http://www.ijcmas.com