Iron, abundance bacteria

S can be more abundant than even N, e.g. in iron-oxidizing bacteria (Franzle and Noack 2008), with cystein and methionine residues more capable of binding metals than sulfate ions. 

Emerson, D., and Moyer, C. (1997). Isolation and chai acterization of novel iron-oxidizing bacteria that grow at circumneutral pH. Appl. Environ. Microbiol. 63, 4784-4792. Emerson, D., and Moyer, C. L. (2002). Neutrophilic Fe-oxidizing bacteria ai e abundant... 

For most living bacteria (lactobacilli being the only notable exception [154]) iron is an essential nutrient. Iron is not readily available under normal conditions, although it is the fourth most abundant metal on earth. In the environment it is mainly found as a component of insoluble hydroxides in biological systems it is chelated by high-affinity iron binding proteins (e.g. transferrins,... 

The second heme oxygenase (HO-2) is distributed widely among tissues, but it is most abundant in certain neurons in the brain.437 4373 Its major function may be to generate CO, which is now recognized as a probable neurohormone (Chapter 30). Bacteria, such as Corynebacterium diphtheriae, employ their own heme oxygenase as a means of recovering iron that they need for growth.438... 

The metal ions of major biological significance are indicated in Figure 1, which shows part of the Periodic Table. Some information on the distribution and concentration levels of these metals in living systems is shown in Table 1. The transition metals and zinc are usually regarded as trace elements, as they are present in very small amounts. Of the transition elements, iron is the most abundant metal, and probably the most well studied. Iron is essential for all living systems with the exception of certain members of the lactic acid bacteria, which grow in environments notoriously low in iron, such as milk. Lactic acid bacteria are devoid of cytochromes, peroxidases... 

Iron is the most abundant metal on earth and the commonest electron transfer agents involve iron complexes. Life is thought to have evolved in reductive conditions, in which the dominant form of iron would be as iron sulfide, not iron oxide. The simplest forms of electron transfer agents (found in plants and bacteria) involve iron with thiolate ligands. Some simple electron transfer proteins, such as rubredoxin, contain a single iron centre in an S4 donor environment within a protein (Fig. 10-7). 

Several hypotheses of the possible relationship between the deposition of the cherty iron formation and the activity of various primitive organisms have been defined and repeatedly proofs have been offered to support the occurrence of definite biota. In fact, some indication is available for the assumption, that life was abundant at the time and place of deposition of the BIF and that iron formations themselves were deposited as a result of biological processes. It is presumed in this context, that iron-bacteria reacted with the oxygen acceptor Fe2 + in solution and then deposited the trivalent and/or trivalentdivalent iron as precipitated compounds along with other residues resulting from biomass. All these components... 

Solid phase chemical analyses included determination of total organic C content, and the distribution of S between iron monosulfides (acid-volatile sulfur or AVS) and pyrite (the difference between total reducible sulfur and AVS). Total organic carbon was measured coulometrically following combustion at 1050°C (7). Acid-volatile sulfur and total reducible sulfur analyses followed the procedure of Canfield et al. (8). A microbiological assay of the abundance of sulfate reducing bacteria was performed according to (9). 

Not only is iron involved in an enormous range of functions, it is also found in the whole gamut of life forms from bacteria to man. Iron is extremely abundant in the earth s crust and it has two readily interconverted oxidation states doubtless these properties have led to evolutionary selection for use in many life processes. Table 17-E-2 shows the principal forms in which iron is found in the human body. 

Virtually all microorganisms—with the exception of certain lactobacilli— require iron as cofactor of many metabolic enzymes and regulatory proteins because of its ability to exist in two stable oxidation states. Although iron is one of the most abundant elements in the environment, it is often a limiting factor for bacterial growth. This is so because of the formation of insoluble ferric hydroxide complexes under aerobic conditions at neutral pH, which impose severe restrictions on the availability of the element. Consequently, bacteria have evolved specialized high-affinity transport systems in order to acquire sufficient amounts of this essential element. 

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