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An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environment. Anaerobes may be unicellular (e.g. protozoans, [1] bacteria [2]) or multicellular. [3]
Anaerobic respiration is a critical component of the global nitrogen, iron, sulfur, and carbon cycles through the reduction of the oxyanions of nitrogen, sulfur, and carbon to more-reduced compounds. The biogeochemical cycling of these compounds, which depends upon anaerobic respiration, significantly impacts the carbon cycle and global warming ...
[1] [2] [3] [5] The variability in oxygen tolerance of obligate anaerobes (<0.5 to 8% O 2) is thought to reflect the quantity of superoxide dismutase and catalase being produced. [2] [3] In 1986, Carlioz and Touati performed experiments which support the idea that reactive oxygen species may be toxic to anaerobes.
Anaerobic bacteria can be divided into strict anaerobes that can not grow in the presence of more than 0.5% oxygen and moderate anaerobic bacteria that are able of growing between 2 and 8% oxygen. [1] Anaerobic bacteria usually do not possess catalase, but some can generate superoxide dismutase which protects them from oxygen.
Desulfovibrio vulgaris is the best-studied sulfate-reducing microorganism species; the bar in the upper right is 0.5 micrometre long.. Sulfate-reducing microorganisms (SRM) or sulfate-reducing prokaryotes (SRP) are a group composed of sulfate-reducing bacteria (SRB) and sulfate-reducing archaea (SRA), both of which can perform anaerobic respiration utilizing sulfate (SO 2−
A facultative anaerobic organism is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent. [1] [2] Some examples of facultatively anaerobic bacteria are Staphylococcus spp., [3] Escherichia coli, Salmonella, Listeria spp., [4] Shewanella oneidensis and Yersinia ...
Anaerobic digestion, the use of anaerobic bacteria to break down waste, with biogas as a byproduct Anaerobic clarigester, an anaerobic digester that treats dilute biodegradable feedstocks and allows different retention times for solids and liquids; Anaerobic contact process, an anaerobic digester with a set of reactors in series
In both aerobic and anaerobic systems the growing and reproducing microorganisms within them require a source of elemental oxygen to survive. [1] In an anaerobic system there is an absence of gaseous oxygen. In an anaerobic digester, gaseous oxygen is prevented from entering the system through physical containment in sealed tanks.