Microbial Resistance to Metals in the Environment

• Published in: Ecotoxicology and Environmental Safety 2000-03, Vol.45 (3), p.198-207
• Main Authors: Bruins, Mark R., Kapil, Sanjay, Oehme, Frederick W.
• Format: Article
• Language: English
• Subjects: Adaptation, Biological - drug effects; Animal, plant and microbial ecology; Applied ecology; Bacteria - drug effects; Bacteria - metabolism; Biological and medical sciences; Biological Transport, Active - drug effects; Cell Membrane Permeability - drug effects; Ecotoxicology, biological effects of pollution; Environmental Pollutants - metabolism; Environmental Pollutants - pharmacokinetics; Environmental Pollutants - pharmacology; essential metals; Extracellular Space - metabolism; Fundamental and applied biological sciences. Psychology; General aspects; heavy metals; Inactivation, Metabolic; Intracellular Fluid - metabolism; Metals - metabolism; Metals - pharmacokinetics; Metals - toxicity; nonessential metals; Protein Binding - drug effects; resistance mechanisms
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1006/eesa.1999.1860

Many microorganisms demonstrate resistance to metals in water, soil and industrial waste. Genes located on chromosomes, plasmids, or transposons encode specific resistance to a variety of metal ions. Some metals, such as cobalt, copper, nickel, serve as micronutrients and are used for redox processes, to stabilize molecules through electrostatic interactions, as components of various enzymes, and for regulation of osmotic pressure. Most metals are nonessential, have no nutrient value, and are potentially toxic to microorganisms. These toxic metals interact with essential cellular components through covalent and ionic bonding. At high levels, both essential and nonessential metals can damage cell membranes, alter enzyme specificity, disrupt cellular functions, and damage the structure of DNA. Microorganisms have adapted to the presence of both nutrient and nonessential metals by developing a variety of resistance mechanisms. Six metal resistance mechanisms exist: exclusion by permeability barrier, intra- and extra-cellular sequestration, active transport efflux pumps, enzymatic detoxification, and reduction in the sensitivity of cellular targets to metal ions. The understanding of how microorganisms resist metals can provide insight into strategies for their detoxification or removal from the environment.