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Microbial Ecology
Published in Volodymyr Ivanov, Environmental Microbiology for Engineers, 2020
The following groups of microorganisms differ in their relation to oxygen: Obligate anaerobic prokaryotes produce energy by fermentation (it is an intramolecular oxidation–reduction without an external acceptor of electrons) or by anoxic respiration (electron acceptors are not oxygen); they can die after contact with oxygen because they have no protection against such the toxic products of oxygen reduction such as hydrogen peroxide (H2O2), superoxide radical (O2−), and hydroxyl radical (OH●).Tolerant anaerobes produce energy by fermentation or by anoxic respiration but can survive after contact with oxygen due to a protective mechanism against oxygen radicals.Facultative anaerobic bacteria are capable of producing energy either anaerobically if oxygen is absent or by aerobic respiration if oxygen is present.Microaerophilic bacteria prefer low concentrations of dissolved oxygen in the medium.Obligate aerobes produce energy by aerobic respiration only.
Biological Responses in Context
Published in Arthur T. Johnson, Biology for Engineers, 2019
Two genera of bacteria form endospores. The first is the genus Clostridium, an obligate anaerobe. C. tetani causes the disease tetanus; C. botulinum causes botulism; C. perfringens causes gas gangrene and foodborne diarrhea. The second genus is Bacillus, which includes B. anthracis, causing anthrax, B. thuringiensis, a bacterial pathogen, and B. cereus, which can cause a form of food poisoning (Tortora et al., 2001).
Bioremediation
Published in Domenic Grasso, Hazardous Waste Site Remediation, 2017
Sometimes terms like “obligate anaerobe” are used for classification, which indicates that the microorganism can not grow in the presence of air. Therefore, the species of this microbe would be more abundant in the oxygen depleted zones.
Right on target: using plants and microbes to remediate explosives
Published in International Journal of Phytoremediation, 2019
Elizabeth L. Rylott, Neil C. Bruce
Obligate anaerobic bacteria, such as Clostridium sp. are able to oxidize the amino groups of TAT, to form 2,4,6-trihydroxytoluene, which is then degraded to intermediates in the Tricarboxylic Acid (TCA) cycle (Figure 1; Esteve-Nunez et al. 2001). Compared to bacterial rates, more substantial mineralization of TNT has been reported for a number of lignolytic fungi including Phanerochaete chrysosporium (Hawari et al. 1999; Esteve-Nunez et al. 2001). Following reductive transformation of one or more nitro groups, mineralization is catalyzed nonspecifically by the indirect activity of lignin-degrading enzymes including laccases and manganese peroxidases. Mineralization of DNTs has also been shown in P. chrysosporium (Valli et al. 1992), with bacterial pathways elucidated for both 2,4-DNT (Nishino et al2000) and 2,6-DNT (Johnson and Spain 2003).