China
Africa
Explore chapters and articles related to this topic
Nitrogen Cycle Bacteria in Agricultural Soils
Published in Vivek Kumar, Rhizomicrobiome Dynamics in Bioremediation, 2021
Guillermo Bravo, Paulina Vega-Celedón, Constanza Macaya, Ingrid-Nicole Vasconez, Michael Seeger
Nitrification Nitrification is an essential process in the nitrogen cycle in soils, which involves the biological oxidation of ammonia via nitrite to nitrate in the presence of oxygen by bacteria and archaea (Hernández et al. 2011). Several enzymes participate in the oxidation of reduced nitrogen compounds. The transmembrane enzyme ammonia monooxygenase oxidizes ammonia to hydroxylamine. NH2OH is subsequently oxidized by hydroxylamine oxidoreductase to nitrite (Hernández et al. 2011). Due to the high solubility of nitrate in agricultural systems, nitrification may cause negative effects, generating losses in crop production, and causing water eutrophication. It has been estimated that nitrification produces worldwide losses of 37 Tg of N year–1 in soil (Mosier et al. 2004).
Fundamentals and Modeling Aspects of Bioventing
Published in Subhas K. Sikdar, Robert L. Irvine, Fundamentals and Applications, 2017
C. M. Tellez, A. Aguilar-Aguila, R. G. Arnold, R. Z. Guzman
There are five genera in this group: Nitrosomonas, Nitrosococcus, Nitrospira, Nitrosolobus, and Nitrosovibrio. The best studied species of ammonia oxidizers is Nitrosomonas europaea, an obligate chemolitho-troph that initiates nitrification by the reductant-dependent oxidation of ammonia to hydroxylamine using ammonia monooxygenase (AMO). Reductant for AMO-catalyzed reactions is provided by the further oxidation of hydroxylamine to nitrite by hydroxylamine oxidoreductase (Figure 6). There is evidence that the AMO of N. europaea can also initiate cometabolic transformation of hydrocarbons (Hyman and Wood, 1983; 1984) and haloaliphatic compounds, including TCE (Arciero et al., 1989; Vanelli et al., 1990). The situation is entirely parallel to that of the methanotrophs in that halogenated substrates are transformed by both AMO and MMO without any direct metabolic benefit. Both enzymes consume reductant in the process, which must be replenished by metabolic activities at some expense to the organisms. For this reason, a primary or energy-yielding substrate is necessary for sustained cometabolic activity.
Alcohol Fuels
Published in M.R. Riazi, David Chiaramonti, Biofuels Production and Processing Technology, 2017
Elia Tomás-Pejó, Antonio D. Moreno, M.R. Riazi, David Chiaramonti
AOM has also been observed in ammonia-oxidizing bacteria (AOB) (Taher and Chandran 2013). AOBs are mainly chemolithoautotrophs that oxidize ammonia (NH3) into nitrite (NO2−) using CO2 as the carbon source and have also the ability to oxidize methane to methanol under certain specific conditions. Oxidation of NH3 to NO2− takes place in two steps. First, ammonia monooxygenase (AMO) oxidizes NH3 to hydroxylamine (NH2OH) and, second, hydroxylamine oxidoreductase (HAO) oxidizes NH2OH to NO2−. Co-oxidation of methane to methanol is performed by AMO during oxidation of NH3 to NO2− (Figure 13.3).
Harnessing biodegradation potential of rapid sand filtration for organic micropollutant removal from drinking water: A review
Published in Critical Reviews in Environmental Science and Technology, 2021
Jinsong Wang, David de Ridder, Albert van der Wal, Nora B. Sutton
Biological RSF is commonly used to remove ammonium from water sources by nitrification (de Vet et al., 2011; Kors et al., 1998; van der Aa et al., 2002). Nitrification includes two biological processes, which are conducted by ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria, respectively (Niu et al., 2013). The ammonia monooxygenase enzyme has a broad substrate specificity, and not only catalyzes the oxidation reaction of ammonium, but also that of such compounds as alkanes, alkenes, aromatic and alicyclic hydrocarbons, halogenated hydrocarbons, and sulfonated hydrocarbons (Arciero et al., 1989; Hyman et al., 1988; Im & Semrau, 2011). It has been shown that nitrifying bacteria are capable of co-metabolizing various OMPs (Men et al., 2016; Roh et al., 2009; Shi et al., 2004; Sun et al., 2012).
Influence of metronidazole on activated sludge activity
Published in Environmental Technology, 2021
Oscar Velasco-Garduño, Gehovana González-Blanco, María del Carmen Fajardo-Ortiz, Ricardo Beristain-Cardoso
The nitrification biochemical pathway necessarily requires enzymatic control to complete the route. The first step of nitrification is catalysed by Ammonia Monooxygenase (AMO) enzyme which is a copper membrane monooxygenase that oxidises ammonium to nitrite via hydroxylamine (NH2OH). AMO also is able to oxidise partially a broad group of organic compounds such as alkenes, methanol, halogenated hydrocarbons and aromatic compounds [26]. The last step of nitrification is the nitrite (NO2−) oxidation to nitrate (NO3−) carried out for the Nitrite Oxidizing Bacteria (NOB) which depend on the Nitrite Oxidoreductase enzyme (NORe). NORe constitutes from 10 to 30% of the total protein in the cellular membrane [26]. For example, in the bacterium Nitrobacter hamburgensis three major enzymes were observed with masses of 116, 65 and 32 kDa. The 116 kDa subunit contains a molybdenum cofactor, which acts as the substrate-binding site to activate the enzyme [27]. The cofactors (metallic ions) or trace elements are essentials for activating the enzymes to carry out the nitrification biochemical pathway successfully. Ali et al. [8] observed that metronidazole can chelate different metals such as manganese, iron, cobalt, nickel, copper, mercury and cadmium. Therefore, if the metallic ions are chelated avoiding their incorporation into the cell, the biochemical pathway will be stopped at some point. In the present work, all batch cultures showed more than 97% of metronidazole concentration in the liquid medium, during all reaction times. These experimental results suggested that metronidazole did not cross the cell wall, but interactions with cell membrane or metals might occur. The nitrite oxidation was the biochemical step more affected by metronidazole; this biochemical step is catalysed by the NORe which depends on molybdenum. Perhaps, the presence of metronidazole also might have chelated the molybdenum, stopping the NOB activity, as it was observed by Ali et al. [8] with other kinds of metals.