About this Research Topic
Microbial iron metabolism is an important in both marine and terrestrial environments as it relates to ocean productivity, storage of carbon, emissions of greenhouse gas and the fate of nutrients, toxic metals, and metalloids. Iron is a cofactor for fundamental biochemical activities, including energy metabolism, oxygen transport, redox reactions, and DNA synthesis. Research on cellular iron metabolism is currently more focused on iron export or import proteins. Iron metabolic pathways are regulated in response to iron availability in the cells, such as transferrin, the transferrin receptor and ferritin. Due to its requirement in these biological processes, its acquisition and cycling exhibit the potential to structure microbial communities, and to control productivity on the ecosystem scale. Thus, iron biochemical cycling of microorganisms is also significant for iron utilization.
Microbial Fe (II) oxidation coupled to cell growth is important in affecting the geochemical processes in soil, sedimentary, and aqeuous environments. In particular, the metabolic activity of acidophilic and neutrophilic iron-oxidizing bacteria (FeOB) under oxic or anoxic conditions promote the oxidation of Fe (II) to Fe (III) and the precipitation of biogenic iron oxides as extracellular precipitates near or on the bacterial cells. Recent work has significantly improved our understanding of the diversity, physiology, ecology, and environmental influence of the microorganisms that transform iron. Iron transport genes such as Fur, TonB, ExbB, ExbD, Sit and EfeU are known to play key roles in iron uptake and can influence the environmental behaviour of Fe-minerals, including those associated with soil pollution.
Fe (III)-reducing bacteria (FeRB) couple the reduction of ferric iron with the oxidation of organic or inorganic electron donors by using both amorphous Fe (III) (hydro)oxides, and more, crystalline Fe (III) (hydro)oxides as electron acceptors. Iron reduction metabolic pathways may include both pathways for assimilatory reduction and dissimilatory reduction. Assimilatory pathways are associated with Fe (III) transported into cells and reduced by iron reductases for Fe utilization as a cofactor in cellular processes. For dissimilatory pathways, Fe (III)acts as the terminal electron acceptor and is reduced on the cell surface or at sites away from the cell. A variety of Fe mineral types, including ferrihydrite, magnetite, goethite, hematite, green rust, vivianite, siderite, and dissolved Fe (II) are known to be involved in Fe-reduction and oxidation. The redox potentials of diverse Fe (II)-Fe (III) redox couples lie between those of oxidized and reduced carbon, nitrogen, phosphorus, oxygen, and sulfur redox species, which reveal that iron is tightly associated with the major biogeochemical element cycles.
This Research Topic aims to provide an overview of new insights into both iron metabolism and biochemical cycling. The purpose of this is to expand existing knowledge on iron oxidation and reduction processes and the related transportation of electrons. Progress in iron cycling has been facilitated by recent rapid technological advances, especially in genomics and isotopic approaches.
Microbial Fe (II) oxidation coupled to cell growth is important in affecting the geochemical processes in soil, sedimentary, and aqeuous environments. In particular, the metabolic activity of acidophilic and neutrophilic iron-oxidizing bacteria (FeOB) under oxic or anoxic conditions promote the oxidation of Fe (II) to Fe (III) and the precipitation of biogenic iron oxides as extracellular precipitates near or on the bacterial cells. Recent work has significantly improved our understanding of the diversity, physiology, ecology, and environmental influence of the microorganisms that transform iron. Iron transport genes such as Fur, TonB, ExbB, ExbD, Sit and EfeU are known to play key roles in iron uptake and can influence the environmental behaviour of Fe-minerals, including those associated with soil pollution.
Fe (III)-reducing bacteria (FeRB) couple the reduction of ferric iron with the oxidation of organic or inorganic electron donors by using both amorphous Fe (III) (hydro)oxides, and more, crystalline Fe (III) (hydro)oxides as electron acceptors. Iron reduction metabolic pathways may include both pathways for assimilatory reduction and dissimilatory reduction. Assimilatory pathways are associated with Fe (III) transported into cells and reduced by iron reductases for Fe utilization as a cofactor in cellular processes. For dissimilatory pathways, Fe (III)acts as the terminal electron acceptor and is reduced on the cell surface or at sites away from the cell. A variety of Fe mineral types, including ferrihydrite, magnetite, goethite, hematite, green rust, vivianite, siderite, and dissolved Fe (II) are known to be involved in Fe-reduction and oxidation. The redox potentials of diverse Fe (II)-Fe (III) redox couples lie between those of oxidized and reduced carbon, nitrogen, phosphorus, oxygen, and sulfur redox species, which reveal that iron is tightly associated with the major biogeochemical element cycles.
This Research Topic aims to provide an overview of new insights into both iron metabolism and biochemical cycling. The purpose of this is to expand existing knowledge on iron oxidation and reduction processes and the related transportation of electrons. Progress in iron cycling has been facilitated by recent rapid technological advances, especially in genomics and isotopic approaches.
Keywords: iron metabolism, iron oxidation, iron reduction, microbes, microorganisms, biochemical cycling, oxygen transport
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