Heavy Metal-Microbe

Heavy Metal-Microbe Interactions and Microbial Response... 

Similar to other types of water treatment, AC filtration is effective for some contaminants and not effective for others. AC filtration does not remove microbes, sodium, nitrates, fluoride, and hardness. Lead and other heavy metals are removed only by a very specific type of AC filter. Unless the manufacturer states that its product will remove heavy metals, one should assume that the AC filter is not effective in removing them. 

Some microbes are able to decrease the permeability of their membranes to prevent toxic metals from entering. If the toxic metals are not able to physically enter the cell, they will not be able to affect vital metal-sensitive structures, such as proteins. One way to prevent heavy metals from entering is by decreasing the production of membrane channel proteins.18 It is also possible for the metal-binding sites in the membrane and periplasm to be saturated with nontoxic metals.37 A third possibility is the formation of an extracellular polysaccharide coat, which binds and prevents metals from reaching the surface of the cell.24,38... 

Microbes that lack a specific active transport system for removing toxic metals may be able to sequester heavy metals either inside or outside of the cell. Intracellular sequestration occurs when cytoplasmic metal-binding molecules are produced in response to metal stress, preventing the metals from interacting with vital cell structures. The two most common molecules used for intracellular... 

Ramamoorthy, S. and Kushner, D.J., Binding of mercuric and other heavy metal ions by microbial growth media, Microb Ecol, 2 (2), 162-176, 1975. 

Rudd, T., Sterritt, R.M., and Lester, J.N., Mass balance of heavy metal uptake by encapsulated cultures of Klebsiella aerogenes, Microb Ecol, 9 (3), 261-272, 1983. 

Babich, H. and Stotzky, G., Heavy metal toxicity to microbe-mediated ecologic processes A review and potential application to regulatory policies, Environ Res, 36 (1), 111-137, 1985. 

Biosorption strategies consist of a group of applications involving the detoxification of hazardous substances such as heavy metals instead of transferring them from one medium to another by means of biosorbents, which may be either microbes or plants. Biosorption options are generally characterized as being less disruptive and may henceforth be carried out on-site, thereby eliminating the need to transport the toxic materials to treatment sites.12 Biosorption is a very cost-effective method... 

Collins Y.E., Stotzky G. Factors affecting the toxicity of heavy metals to microbes. In Metal Ions and Bacteria, Beveridge T.J, Doyle R.J., eds. New York, NY Wiley, 1989. 

Mn2+ active transport system in Staphylococcus aureus. These metal-microbe interactions result in decrease microbial growth, abnormal morphological changes, and inhibition of biochemical processes in individual (Akmal et al. 2005a,b). The toxic effects of metals can be seen on a community level as well. In response to metal toxicity, overall community numbers and diversity decrease. Soil is a living system where all biochemical activities proceed through enzymatic processes. Heavy metals have also adverse effects on enzyme activities (Fig. 1). 

According to the heavy metals effects, the soil microbes, crops and ground waters as a source of drinking water, are the most important receptors. During migration in the food web, the heavy metals, especially Cd and Hg, can affect also higher organisms,... 

Keywords Biosorption, Heavy metal, Bioremediation, Biotransformation, Genetically modified microbes... 

Recent Innovative Approaches and Role of Microbes Towards Ecofriendly Remediation of Heavy Metals... 

McGrath, S.P. Effects of heavy metals from sewage sludge on soil microbes in agricultural ecosystems. In Toxic Metals in Soil-Plant Systems Ross, S.M., Ed. John Wiley Sons Ltd New York, 1994 247-274. 

Baath, E. (1989). Effects of heavy metals in soil on microbial processes and populations (a review). Water, Air, and Soil Pollution, 47, 335—79-Babich, H. Stotzky, G. (1980). Environmental factors that influence the toxicity of heavy metal and gaseous pollutants to microorganisms. Critical Reviews in Microbiology, 8,99-145. Babich, H. Stotzky, G. (1985). Heavy metal toxicity to microbe-mediated ecologic... 

Gadd, G. M. (1986). Fungal responses towards heavy metals. In Microbes in Extreme Environments, ed. R. A. Herbert G. A. Codd, pp. 83-110. New York Academic Press. 

Williams, J. W. and S. Silver. 1984. Bacterial resistance and detoxification of heavy metals. Enzyme Microb. Technol. 6 530-537. 

Most faucet units and pitchers use carbon filters that absorb lead, chlorine by-products, and some organic chemicals, as well as odors and tastes. They won t remove heavy metals, pesticides, nitrites, bacteria, or microbes, but they are the least-expensive filter type and are sufficient for most needs. 

Rosen, B.P. 2002. Transport and detoxification systems for transition metals, heavy metals and metalloids in eukaryotic and prokaryotic microbes. Comparative Biochemistry and Physiology—A Molecular and Integrative Physiology, 133 689-93. 

Gadd, G. M., and White, C. (1989). Heavy metal and radionuclide accumulation and toxicity in fungi and yeasts. In Metal-Microbe Interactions, ed. Poole, R. K., and Gadd, G. M., IRL Press, Oxford, 19-38. 

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