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(NAS Colloquium) Geology, Mineralogy, and Human Welfare (1999) / Chapter Skim
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Biological Impact on Mineral Dissolution: Application of the Lichen Model to Understanding Mineral Weathering in the Rhizosphere
Pages 3404-3411

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From page 3404...
... Below fungi-mineral interfaces, mineral surfaces are exposed to dissolved metabolic byproducts. Through this indirect process, microorganisms can accelerate mineral dissolution, leading to enhanced porosity and permeability and colonization by microbial communities.
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From page 3405...
... Clay precipitation reactions may provide proton sources or sinks, and a variety of silicate minerals may serve as sources of metal reductive and oxidative power. In this paper, we discuss physical, chemical, and biochemical aspects of mineral dissolution and clay formation.
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From page 3406...
... was characterized by transmission electron microscopy. Mineral surfaces in microbially colonized regions are coated in complex mixtures of high molecular weight polymers, clays, and oxyhydroxides.
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From page 3407...
... Zone 2 is a region of extreme mineral weathering, characterized by direct contact between cells, extracellular polymers, associated compounds, and mineral surfaces. Complex, nanometer-scale mixture of clay products, organic polymers, and primary minerals are common (Fig.
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From page 3408...
... using undifferentiated and medium molecular weight polysaccharides demonstrate enhanced feldspar dissolution by two to three orders of magnitude under some conditions. scanning electron microscope observations and unpublished experimental data, suggest that solubilization of secondary phosphates results from microbial colonization (Fig.
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From page 3409...
... However, these extracellular polymers may have more direct chemical effects on mineral weathering as well. The effect of high molecular weight organic molecules on mineral dissolution rates was quantified by using dissolution experiments involving model extracellular polymers.
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From page 3410...
... It should be possible to increase the rates of soil development and optimize methods used to maintain or increase soil fertility through knowledge about microbial populations and how microbes cooperate to affect mineral dissolution, degradation of organic compounds, immobilization of ions, precipitation of minerals, and change in solution chemistry. For example, identification of microbial species capable of solubilizing secondary phosphates may provide new insights for improved fertilizer efficiency (e.g., simultaneous addition of microorganisms or microbial compounds with phosphate fertilizers)
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From page 3411...
... (1989) Clays Clay Miner.
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Key Terms

  • mineral surfaces
  • mineral dissolution
  • microbial populations
  • dissolution rates
  • organic acids

  • molecular weight
  • secondary minerals
  • weathering reactions
  • chemical weathering
  • silicate mineral

  • plant roots
  • microbial colonization
  • soil fertility
  • transmission electron
  • natural environments

  • secondary phosphates
  • electron microscope
  • extracellular polymers
  • weight organic
  • microbial cells

  • fungal hyphae
  • mineral surface
  • microbially mediated
  • insoluble secondary
  • affect mineral

  • inorganic reactions
  • phosphate minerals
  • grain boundaries
  • molecular biological
  • acid production


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