Metals microbial interactions

Heavy Metal-Microbe Interactions and Microbial Response... 

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). 

Filer JM, Mojzsis SJ, Arrhenius G (1997) Carbon isotope evidence for early life discussion. Nature 386 665 Emerson D (2000) Microbial oxidation of Ee(II) and Mn(II) at circumneutral pH. In Environmental metal-microbe interactions. Lovley DR (ed) ASM Press, Washington DC, p 31-52 Ewers WE (1983) Chemical factors in the deposition and diagenesis of banded iron-formation. In Iron formations facts and problems. Trendall AF, Morris RC (eds) Elsevier, Amsterdam, p 491-512 Farley KJ, Dzombak DA, Morel FMM (1985) A surface precipitation model for the sorption of cations on metal oxides. J Colloid Interface Sci 106 226-242... 

Intracellular distribution of essential transition metals is mediated by specific metallochaperones and transporters localized in endomembranes. In other words, the major processes involved in hyperaccumulation of trace metals from the contaminated medium to the shoots by hyperaccumulators as proposed by Yang et al. (2005) include bioactivation of metals in the rhizosphere through root-microbial interaction enhanced uptake by metal transporters in the plasma membranes detoxification of metals by distributing metals to the apoplasts such as binding to cell walls and chelation of metals in the cytoplasm with various ligands (such as PCs, metallothioneins, metal-binding proteins) and sequestration of metals into the vacuole by tonoplast-located transporters. 

In this chapter, some aspects of the transformation and mobilization of metals by microorganisms in relation to the soil environment have been outlined. It seems evident that metal-microbe interactions are important in several soil contexts, not least in the biogeochemical cycling of metals, associated elements, and nutrients, and in plant productivity. The application and potential of many natural microbial and microbe-plant processes are also growing topics in the area of bioremediation. However, analysis and understanding of the effects of toxic metals on microbial communities is relatively limited despite extensive research, and many studies are site specific. Clearly, the complexity of interactions between metal species and soil components, as well as between metal... 

Hamilton, W. A. (2003). Microbially influenced corrosion as a model system for the study of metal microbe interactions a unifying electron transfer hypothesis. Biofouling 19, 65-76. 

The differences between clones may depend on a combined effect of plant exudate and microbial effects on the exudate (Marschner, 1995). In studies under nonsterile conditions, rhizosphere microbes may alter the chemical composition of root exudates. Therefore, the differences between high and low metal soil condition as well as different metals in spiked soil can be due to toxic metal effects or effects resulting from an excess of chloride on microbes. When comparing various clones the differences in exudate composition could have been due to various microbe-clone relationships. One should, however, keep in mind that a microbe-plant relationship is present in real environment where we also find these metal-accumulation differences between clones. Whether the differences in rhizosphere processes are due to plants alone or a combination with microbial interactions has to be further investigated. 

One problem with trying to ascertain the relative radionuclide-complexing ability of different environmental surfaces is a lack of consistency in the framework that is used for evaluating sorption (complexation) among surface types. Metal oxides (including clays) have been the subject of a vast amount of experimental research and modeling. While both natural organic matter and microbial surfaces have received attention for their ability to accumulate metal ion (bacteria and viruses much less so), there has been relatively little work done on the simulation of metal-NOM and metal-bacteria interactions in a manner that is consistent with the surface complexation (SC) approach used for metal oxides. Examples of the application of SC to NOM and bacteria are Westall et al. (1995), and Fein et al. (1997), respectively. As a consequence, it is difficult to predict competition between environmental surface types for radionuclides. 

Kurek E (2002) Microbial mobilization of metals from soil minerals under aerobic conditions. In Huang PM, Bollag J-M, Senesi N (eds) Interactions between soil particles and microorganisms. Impact on the terrestrial ecosystem, vol 8, IUPAC series on analytical and physical chemistry of environmental systems. Wiley, Chichester, UK, pp 189-225... 

Soil Heavy Metal Pollution and Microbial Communities Interactions and Response Assessment... 

Table 2. Effect of Pb and Cd interaction on soil microbial biomass carbon (mg kg-1) (DAA represents days after heavy metal addition different letters within column indicate that treatment means are significantly different at P < 0.01) (Authors unpublished data, 2006)...

Bioavailability of Metals, Nonmetals and Xenobiotics Immobilized on Soil Components, (4) Distribution and Activity of Biomolecules in Terrestrial Systems, (5) Interactions between Soil Microbial Biomass and Organic Matter/Nutrient Transformations, and (6) Impact of Interactions among Soil Mineral Colloids, Organic Matter and Biota on Risk Assessment and Restoration of Terrestrial Ecosystems. There were 2 plenary lectures, 9 invited speakers, 36 oral presentations and 45 posters. Dr. N. Senesi from University of Bari, Italy, presented an IUPAC lecture entitled Metal-Humic... 

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