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The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmospheric nitrogen, making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems.
The Montreal Biodome is a facility located at Olympic Park in the Mercier–Hochelaga-Maisonneuve neighbourhood of Montreal, Quebec, Canada, that allows visitors to walk through replicas of four ecosystems found in the Americas. The building was originally constructed for the 1976 Olympic Games as a velodrome. It hosted both track cycling and judo events. Renovations on the building began in 1989 and in 1992 the indoor nature exhibit was opened.
Anaerobic respiration is respiration using electron acceptors other than molecular oxygen (O2). Although oxygen is not the final electron acceptor, the process still uses a respiratory electron transport chain.
Denitrification is a microbially facilitated process where nitrate (NO3−) is reduced and ultimately produces molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products. Facultative anaerobic bacteria perform denitrification as a type of respiration that reduces oxidized forms of nitrogen in response to the oxidation of an electron donor such as organic matter. The preferred nitrogen electron acceptors in order of most to least thermodynamically favorable include nitrate (NO3−), nitrite (NO2−), nitric oxide (NO), nitrous oxide (N2O) finally resulting in the production of dinitrogen (N2) completing the nitrogen cycle. Denitrifying microbes require a very low oxygen concentration of less than 10%, as well as organic C for energy. Since denitrification can remove NO3−, reducing its leaching to groundwater, it can be strategically used to treat sewage or animal residues of high nitrogen content. Denitrification can leak N2O, which is an ozone-depleting substance and a greenhouse gas that can have a considerable influence on global warming.
In biogeochemistry, remineralisation refers to the breakdown or transformation of organic matter into its simplest inorganic forms. These transformations form a crucial link within ecosystems as they are responsible for liberating the energy stored in organic molecules and recycling matter within the system to be reused as nutrients by other organisms.
Betaproteobacteria are a class of Gram-negative bacteria, and one of the eight classes of the phylum Proteobacteria.
In fishkeeping, a refugium is an appendage to a marine, brackish, or freshwater fish tank that shares the same water supply. It is a separate sump, connected to the main show tank. It is a "refugium" in the sense that it permits organisms to be maintained that would not survive in the main system, whether food animals, anaerobic denitrifying bacteria, or photosynthesizers. For some applications water flow is limited in order to protect plants or animals that require slow flow. The refugium light cycle can be operated opposite to the main tank, in order to keep total system pH more stable (due to the uptake of acid-forming CO2 by photosynthesis occurring in the refugium during its "daylight" hours). One volume guideline for a refugium is 1:10 main tank volume.
Human impact on the nitrogen cycle is diverse. Agricultural and industrial nitrogen (N) inputs to the environment currently exceed inputs from natural N fixation. As a consequence of anthropogenic inputs, the global nitrogen cycle (Fig. 1) has been significantly altered over the past century. Global atmospheric nitrous oxide (N2O) mole fractions have increased from a pre-industrial value of ~270 nmol/mol to ~319 nmol/mol in 2005. Human activities account for over one-third of N2O emissions, most of which are due to the agricultural sector. This article is intended to give a brief review of the history of anthropogenic N inputs, and reported impacts of nitrogen inputs on selected terrestrial and aquatic ecosystems.
In taxonomy, Pseudovibrio is a genus of the Rhizobiaceae. Bacteria belonging to this genus have been often isolated from marine invertebrates and have been described to be metabolically versatile. Recent comparative genomic analyses revealed that these organisms have the genomic potential to produce a great array of systems to interact with their hosts, including type III, IV, VI secretion systems and different type of toxin-like proteins. Moreover, in their genomes several biosynthetic gene clusters producing potentially novel bioactive compounds were recently identified.
Syed Wajih Ahmad Naqvi is an Indian marine scientist and the former director of the National Institute of Oceanography. His work has concentrated in oceanic water chemistry, biogeochemistry, and chemical interrelations with living organisms. He has also performed research on freshwater ecosystems. He was the Chief Indian Scientist of LOHAFEX, an Ocean Iron Fertilization experiment jointly planned by the Council of Scientific Industrial Research (CSIR), India, and Helmholtz Foundation, Germany.
Nitratireductor is a genus of bacteria.
Nitratireductor aquimarinus is a Gram-negative, aerobic bacteria from the genus of Nitratireductor which was isolated from Skeletonema costatum from the Sea of Japan.
Nitratireductor basaltis is a Gram-negative, oxidase- and catalase-positive bacteria from the genus of Nitratireductor which was isolated from black sand from the Soesoggak beach on the Jeju Island in South Korea.
Nitratireductor indicus is a Gram-negative, oxidase- and catalase-positive mobile bacteria from the genus of Nitratireductor which was isolated from deep-sea water of the Indian Ocean.
Nitratireductor kimnyeongensis is a Gram-negative, aerobic, oxidase- and catalase-positive bacteria from the genus of Nitratireductor which was isolated from the Kimnyeong Beach in Jeju from the Republic of Korea.
Nitratireductor lucknowense is a bacterium from the genus of Nitratireductor which was isolated from pesticide contaminated soil in Lucknow in India.
Nitratireductor pacificus is a Gram-negative and motile bacteria from the genus of Nitratireductor which was isolated from enriched sediment from the Pacific Ocean.
Hyphomicrobium nitrativorans is a bacterium from the genus of Hyphomicrobium which was isolated from biofilm at the Montreal Biodome in Canada.
Dissimilatory nitrate reduction to ammonium (DNRA), also known as nitrate/nitrite ammonification, is the result of anaerobic respiration by chemoorganoheterotrophic microbes using nitrate (NO3−) as an electron acceptor for respiration. In anaerobic conditions microbes which undertake DNRA oxidise organic matter and use nitrate (rather than oxygen) as an electron acceptor, reducing it to nitrite, then ammonium (NO3−→NO2−→NH4+).
Nitratireductor lacus is a Gram-negative bacteria from the genus of Nitratireductor which has been isolated from the Yuncheng Salt Lake in China.
References
- ↑ LSPN lpsn.dsmz.de
- ↑ Straininfo of Nitratireductor aquibiodomus
- ↑ UniProt
- ↑ Labbe, N.; Parent, S; Villemur, R (2004). "Nitratireductor aquibiodomus gen. nov., sp. nov., a novel -proteobacterium from the marine denitrification system of the Montreal Biodome (Canada)". International Journal of Systematic and Evolutionary Microbiology. 54 (Pt 1): 269–73. doi: 10.1099/ijs.0.02793-0 . PMID 14742492.
- ↑ Taxonomy Browser
- ↑ Deutsche Sammlung von Mikroorganismen und Zellkulturen