Hei,
legger ved utdrag fra tre av mange rapporter om funn av Nitrospirae og deres betydning for oksidering av nitritt, sett sammen med nitrobacter.
Det finnes mer. Dessuten en studie som konkluderte med akkurat min konklusjon, at nitrobacter ikke er vesentlig for oksidering av nitritt, men at nitrospirae er det. Den finner jeg dessverre ikke igjen blant alt materielet som er tilgjengelig på nettet.
Utdrag fra to rapporter fra
Faculty Center of Ecology Faculty of Life Sciences University of Vienna
Department of Microbial Ecology Environmental genomics of anaerobic ammonium oxidizing bacteria and Nitrospira-like bacteriaApplication of the full-cycle rRNA approach has revealed that in many ecosystems previously not recognized bacteria catalyze key steps of the biogeochemical nitrogen cycle. For example, uncultured members of the phylum Nitrospirae are important nitrite oxidizers in many natural habitats and in wastewater treatment plants. These novel nitrite oxidizers are members of a unique bacterial phylum, which harbors also other highly interesting bacteria like the thermophilic sulfate reducers of the genus Thermodesulfovibrio and the acidophilic iron oxidizers of the genus Leptospirillum. In addition, anaerobic ammonium oxidation (Anammox) is mediated by novel, uncultured, deep branching members of the Planctomycetales, which are of significant biotechnological interest………
This study is undertaken in collaboration with Mike Jetten (University of Nijmegen, The Netherlands), Jean Weissenbach and Denis LePaslier (Genoscope, Evry, France), and Eva Spieck (University of Hamburg, Germany).
Biodiversity and ecophysiology of nitrite-oxidizing bacteria Nitrite-oxidizing bacteria (NOB) catalyze the second step of aerobic nitrification, the oxidation of nitrite (NO2-) to nitrate (NO3-). According to textbook knowledge, Nitrobacter species are the main NOB in most natural habitats and in biological wastewater treatment. These Nitrobacter species are relatively easy to cultivate and can be isolated from many environmental samples. Only recently, cultivation-independent methods revealed that novel, yet uncultured NOB are far more important than Nitrobacter in wastewater treatment plants (Burrell et al., 1998; Juretschko et al., 1998; Schramm et al., 1998). These bacteria belong to the genus Nitrospira, which is part of the bacterial phylum Nitrospirae (Ehrich et al., 1995), and are not related to Nitrobacter.
Uncultured Nitrospira-like bacteria have meanwhile been found in many habitats, including freshwater and marine environments, soil, and the rhizosphere (e. g., Bartosch et al., 2002). The large diversity and high abundance of Nitrospira-like bacteria in natural habitats and in wastewater treatment plants indicate that these NOB are very competitive and adaptable and play key roles for nitrogen cycling in many ecosystems.
Investigated by: Holger Daims, Kilian Stoecker, Frank Maixner, Karin Hace, Sebastian Lücker, Roland Hatzenpichler, Gertrude Wegl
Identification and Activities In Situ of Nitrosospira and Nitrospira spp. as Dominant Populations in a Nitrifying Fluidized Bed Reactor
Andreas Schramm,1,* Dirk de Beer,1 Michael Wagner,2 and Rudolf Amann1
Max-Planck-Institut für Marine Mikrobiologie, D-28359 Bremen,1 and Lehrstuhl für Mikrobiologie, Technische Universität München, D-80290 Munich,2 Germany
Received 9 February 1998/Accepted 27 May 1998
Bacterial aggregates from a chemolithoautotrophic, nitrifying fluidized bed reactor were investigated with microsensors and rRNA-based molecular techniques. The microprofiles of O2, NH4+, NO2 , and NO3 demonstrated the occurrence of complete nitrification in the outer 125 µm of the aggregates. The ammonia oxidizers were identified as members of the Nitrosospira group by fluorescence in situ hybridization (FISH). No ammonia- or nitrite-oxidizing bacteria of the genus Nitrosomonas or Nitrobacter, respectively, could be detected by FISH. To identify the nitrite oxidizers, a 16S ribosomal DNA clone library was constructed and screened by denaturing gradient gel electrophoresis and selected clones were sequenced. The organisms represented by these sequences formed two phylogenetically distinct clusters affiliated with the nitrite oxidizer Nitrospira moscoviensis. 16S rRNA-targeted oligonucleotide probes were designed for in situ detection of these organisms. FISH analysis showed that the dominant populations of Nitrospira spp. and Nitrosospira spp. formed separate, dense clusters which were in contact with each other and occurred throughout the aggregate. A second, smaller, morphologically and genetically different population of Nitrospira spp. was restricted to the outer nitrifying zones.
Utdrag fra:
Identification of Nitrite-Oxidizing Bacteria with Monoclonal Antibodies Recognizing the Nitrite Oxidoreductase
Sabine Bartosch, Iris Wolgast, Eva Spieck,* and Eberhard Bock
Institut für Allgemeine Botanik, Universität Hamburg, D-22609 Hamburg, Germany
*Corresponding author. Mailing address: Institut für Allgemeine Botanik, Ohnhorststr. 18, D-22609 Hamburg, Germany. Phone: 49 40 42816 426. Fax: 49 40 42816 400. E-mail:
Spieck@mikrobiologie.uni-hamburg.de.
Received January 29, 1999; Accepted May 20, 1999.
Nitrification, the microbial oxidation of ammonia to nitrate, is an integral part of the nitrogen cycle. Chemolithoautotrophic ammonia oxidizers convert ammonia to nitrite, and subsequently nitrite is oxidized to nitrate by chemolithoautotrophic nitrite oxidizers. The two groups of organisms occur together and have been isolated from diverse aerobic environments (reviewed in references 5 and 19).
In natural samples nitrifiers have commonly been analyzed by the most-probable-number technique (23), which is often criticized because the culture conditions are not optimal (3). Antibodies or rRNA-targeted oligonucleotide probes are used for in situ analyses in order to avoid the limitations of the most-probable-number technique. Immunological detection of nitrifiers is limited by the serological diversity of cells originating from the same ecosystem (4, 16, 33). Furthermore, the organisms need to be isolated prior to antibody development. Thus, unknown and possibly unculturable nitrifiers are not detectable. Nitrobacter species have commonly been isolated by standard procedures and therefore are considered the dominant nitrite oxidizers in freshwater and terrestrial ecosystems (5). Therefore, mainly antibodies that recognize Nitrobacter species are known so far. However, in situ analyses performed with rRNA-targeted oligonucleotide probes recently revealed that Nitrospira species and not Nitrobacter species are the dominant nitrite oxidizers in sewage sludge, aquaria, and bioreactors (10, 15, 17, 25).
(This paper is based on the doctoral study of S. Bartosch at the University of Hamburg).
For ytterligere å stille spørsmål ved vedtatte sannheter om nitrifikasjonsprosessen, kan vi se på dette også:
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Bacteria may get demoted as a key player in the nitrogen cycle in soil
Researchers have uncovered evidence that recently discovered micro-organisms are playing a major role in helping to support life on Earth.
Microscopic life forms called archaea, which are thought to exist mainly in extreme environments, have been discovered to outnumber bacteria in an important step in the cycling of nitrogen in soils.
Scientists have found that a group of archaea - crenarchaea - living in soils and seawater can oxidise ammonia, a chemical produced when animal and plant material decomposes, to nitrite. By carrying out genetic analysis of soil samples, the team discovered evidence that Crenarchaea are responsible for most of the world's oxidation of ammonia in soil. This process of nitrification, provides vital nutrients for plants and also leads to production of the greenhouse gas, nitrous oxide.
The finding turns current thinking on its head as researchers had previously thought that bacteria were solely responsible for this important step in the nitrogen cycle.
"Although we knew crenarchaea existed, we did not know what they did or how important they might be," said Jim Prosser from the University of Aberdeen.
"Our findings show that this group of microorganisms, which was unknown just over a decade ago, may be responsible globally for most of the oxidation of ammonia in soil."
