Bacterial response as a determinant of oxidative stress by heavy metal and antibiotics

Abstract

Heavy metals present in earth s crust as natural components are increasingly found in microbial habitat due to several natural and industrial processes. The harmful effects of heavy metal pollution make aquatic environment more susceptible due to close and long duration contact with the soluble metals. Heavy metals used in industry and in household products are, along with antibiotics creating a selective pressure in the environment that leads to the mutations in microorganisms that will allowed them better survive and multiply The earliest large toxic metal contamination response is hardened the fact that have had extreme levels of metal contamination habitat from several decades still have microbial populations and behavior as microbial populations in uncontaminated habitats. The toughest challenges living cells to maintain appropriate concentrations of essential and toxic metals. Such at higher concentrations, however, heavy-metal ions form unspecific complex compounds in the cell, which leads to toxic effects. To survive under metal-stressed conditions, bacteria have evolved several types of mechanisms to tolerate and uptake of heavy metal ions. Bacteria posses number of enzyme and repair activity in response to elevated level of antioxidants provide bulk protection against deleterious reaction involving active oxygen in bacteria. Bacterial efflux pump system contribute major part to expel different types of antibiotics and chemical substance Stress factor (sigma) play an important role in bacteria to survival under harsh condition. Resistant of antibiotic is acquired by genetic makeup of bacterium which can occur by either a genetic mutation or by transfer of antibiotic resistance gene between bacteria in the environment. These mechanisms include the efflux of metal ions outside the cell, and reduction of the heavy metal ions to a less toxic state.