By continuing you agree to the use of cookies. It is therefore necessary to isolate bacterial strains with novel metabolic capabilities and to establish degradation pathways both biochemically and genetically. Currently, many kinds of amino acids and nucleic acids are being produced on an industrial scale by using genetically engineered microbial cells. Inorganic forms of As are more toxic than methylated species (acids and methyl-As dimethyl-As), the methylated and inorganic forms of Se and Cd are highly toxic (Roane & Pepper, 2000; Tabak, 2005). Furthermore, it may be dependent on cell metabolism if, in the presence of toxic metals, the microorganism produces compounds that favor the precipitation process. Only prokaryotes are capable of oxidizing metals such as Mn2+, Fe2+, Co2+, Cu, AsO2-, Se0 or SeO3 2-, or reducing Mn4+, Fe3+, Co3+, AsO4 2-, SeO4 2- or SeO3 2, whilst obtaining energy from these reactions (Gavrilescu, 2004). Therefore, as the pH increases, an increasing number of sites (acetamide chitin, structural polysaccharides of fungi, phosphate and amino groups of nucleic acids, amino and carboxyl groups of proteins and hydroxyl groups of polysaccharides) are replaced by negative charges, increasing the attraction of metallic cations and adsorption on the cell surface. PCs are short, cysteine-rich peptides, with the general structure (γGlu-Cys)nGly (n=2–11) (Zenk, 1996). Sousa et. al., 2001), respectively. With molecular methods enabling the characterization of microbial community structure, metabolic pathways and enzyme activities, the performance of microorganisms under in situ conditions can be improved by making heavy metal bioremediation a much more efficient process. Biosurfactants are natural surfactants synthesized by plants: (saponins), microorganisms (glycolipids) and the bodies of organisms (bile salts), and they have several advantages over industrially-produced surfactants, such as lower toxicity to degrading microorganisms and less recalcitrance in the environment, greater diversity of chemical structures; performance over a broader range of conditions at different temperatures and pHs (Bognolo, 1999). al., 2003; Kim et. al., 1998; Samuelson et. Fourest & Roux (1992) invalidated this hypothesis by attributing the responsibility of the decrease of specific uptake to a shortage of metal concentration in the solution. Also, the expression of proteins on the surface offers an inexpensive alternative for the preparation of affinity adsorbents (Georgiou et. If the chosen GMO recipient proves not to be able to support plasmid maintenance, the transformant bearing gene(s) of interest must undergo transposition of the cloned gene into the host chromosome, where it will remain integrated in a stable manner. Studies on biosorption by Wang & Chen (2006) have focused on selecting the most promising types of biomass and its future success by sorption will depend on interaction between three knowledge areas: biology, chemistry and engineering (Kefala et. The development of new treatment technologies is required at these sources; however, even though there is awareness of this problem, sustainable solutions are not easily accessible. al. One of the most widely used natural biosurfactants in bioremediation is rhamnolipids, produced by Pseudomonas aeruginosa (Bognolo, 1999; Champion et. The treatment of environmental pollution by microorganisms is a promising technology. One way to obviate the problem of plasmid transfer is to use “mini transposons” for the stable integration of genes into the chromosome of recipient strains (De Lorenzo et. al., 2005). Recent biosorption experiments have focused attention on waste materials, which are by-products or residues from large-scale industrial operations. (2006). al., 2005; Paul et. al., 2004a). They have low molecular weight and they are rich in cysteine residues. Publishing on IntechOpen allows authors to earn citations and find new collaborators, meaning more people see your work not only from your own field of study, but from other related fields too. Many indigenous organisms isolated from sites contaminated with heavy metals have tolerance to heavy metal toxicity and these microbial activities have always been the natural starting point for all biotechnological applications. al., 2000). We are IntechOpen, the world's leading publisher of Open Access books. Chen & Georgiou (2002) suggested a solution to bypass this transport problem by expressing MTs on the cell surface. It was transferred by conjugation to P. putida PaW85 and this strain has already been released into the field for the large-scale bioremediation of river water contaminated with phenolics, originating from a fire in an oil shale mine (Peters et. In general, a bacterium that has been recently isolated from a natural environment is more likely to survive when released back into that same environment. al., 2004). al., 1993). Biosorption can be defined as the ability of biological materials to accumulate heavy metals from wastewater through metabolically mediated or physicochemical uptake pathways (Fourest & Roux, 1992). These effects presumably minimize horizontal gene transfer from the GMOs, suggesting that composting could be a safe solution for their disposal after they have completed their required functions. al., 2002 ), activated sludge from sewage treatment plants (Hammaini et.