Metal resistance

From BioMineWiki

Jump to: navigation, search
Methods of metal resistance. Metals can be effluxed from the cell (A); bound either inside or outside the cell (B); reduced uptake due to more specific uptake systems (C); expression of less sensitive proteins (D); and enzymatic conversion of the metal (E).
Methods of metal resistance. Metals can be effluxed from the cell (A); bound either inside or outside the cell (B); reduced uptake due to more specific uptake systems (C); expression of less sensitive proteins (D); and enzymatic conversion of the metal (E).

Even though microbes require a number of metals, most metals are nonessential, have no nutrient value, and will become toxic to microbes if they accumulate above normal physiological concentrations by the action of unspecific, constitutively expressed transport systems. At high intracellular levels, both essential and nonessential metals can cause damage.

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. There are five basic mechanisms that convey an increased level of cellular resistance to metals:

  1. active transport efflux of the toxic metal from the cell;
  2. enzymic conversion;
  3. intra- or extracellular sequestration;
  4. exclusion by a permeability barrier;
  5. reduction in sensitivity of cellular targets.

[1]

Read more

  1. Dopson, M., C. Baker-Austin, P. R. Koppineedi, and P. L. Bond. 2003. Growth in sulfidic mineral environments: metal resistance mechanisms in acidophilic microorganisms. Microbiology 149:1959-1970. [PubMed].
Personal tools