Summary
| Subject keyword(s) | Bacteria, Biological classification, Cell, Life Science, Life science |
|---|---|
| Grade level | Middle School, High School, Higher Education, Informal Education, Vocational/Professional Development Education |
| Intended audience | Educator, Learner |
| Resource type | Audio/Visual |
| Resource format | image, image/gif, image/jpeg, text, text/html |
| Rights | 2006 VirginiaTech |
Found in collection(s)
Click on the logo to get more information about the collection.
Content contained within the resource
NITROSOMONAS SOIL MICROBIOLOGY BIOL/CSES 4684 This webpage was created by GaleBelino Famisan 1. IDENTIFYING CHARACTERISTICS Cells stain gram negative. Aerobic. Obligate chemolithotroph. Short to long rods, appear in pairs or short chains, coccoid forms often observed. Motile (polar flagella) or non-motile. Has cytomembranes that occur in flattened vesicles in peripheral regions of cytoplasm. Growth range 5-30 degrees C. Optimum pH range 5.8-9.5. The percent G+C ranges from 47 to 50%. Oxidizes ammonia to nitrite (1st step in two step process of nitrification). Habitats: soil, sewage, freshwater and marine ecosystems, brackish environments.The above picture shows Nitrosomonas europaea under phase contrastmicroscopy (2,200X). 2. TAXONOMIC DESCRIPTION Nitrosomonas species belong to the family Nitrobacteraceae which containstwo groups responsible for nitrification. The first group oxidizes ammoniato nitrite (Nitrosomonas belongs to this group), the second group oxidizesnitrite to nitrate. Nitrosomonas species grow chemolithotrophically usingreduced inorganic nitrogen compounds as a source of energy. Some speciesof Nitrosomonas utilize urea by way of urease as an ammonia source. Metabolismis aerobic, NH4+ is the electron donor and O2 is the electron acceptor.Most species are motile with flagella located in their polar regions butsome species are nonmotile. DNA homology experiments are used to determine the presence of furtherspecies. Distinguishing characteristics for the species that are used inidentification are the G+C content of DNA, the shape and size of cells,salt requirement, urea utilization, the presence of carboxysomes, and cellprotein patterns. The above picture showsNitrosomonas spp.under electron microscopy(39,000X). 3. ISOLATION AND ECOLOGY Isolation requires a selective media with ammonia as an electron donor andbicarbonate as the sole carbon source. Media requirements include an extensivelywashed high purity agar or a silica gel agar. The media has to be completelyinorganic because growth is inhibited by the presence of organic materials.Also, growth is slow which enable overgrowth of contaminants. Isolationis extremely difficult and colonies formed are very small in diameter. Visibleturbidity may not be seen even after extensive nitrification so the bestmeans for growth detection is to assay for the production of nitrite. Oneto two weeks is needed for incubation, then the chemical assays will revealsuccessful enrichment and an attempt to isolate pure cultures can be made. Nitrosomonas species are found widely distributed in soil and water.They are present where considerable amounts of ammonia are available. Speciesgrow well in lakes and streams that receive inputs of untreated and treatedsewage. They also strive more in neutral and alkaline habitats because acidicenvironments inhibit nitrification. Ammonia tends to accumulate in anaerobichabitats since oxygen is required for ammonia oxidation, but nitrifyingbacteria tend to develop at the thermocline in stratified lakes where ammoniaand oxygen are both present. The above picture shows Nitrosomonas europea under electronmicroscopy (39,600X). 4. ADDITIONAL SOURCES OF INFORMATION Atlas, R.M. 1995. Principles of Microbiology. Mosby. St.Louis, MO. 900 pp. Brock,T.D., M.T. Madigan, J.M. Martinko and J. Parker. 1994. Biologyof Microorganisms. Prentice Hall. New Jersey. 908 pp. Gerhardt, P., R.G. Murray, R.N. Costilow, E.W. Nester, W.A. Wood, N.R.Krieg and G.B. Phillips.eds. 1981. Manual of Methods for General Bacteriology.American Society of Microbiology Press. Washington D.C. p. 125. Holt, J.G., N.R. Krieg, P.H.A. Sneath, J.T. Staley, and S.T. Williams.1994. Bergey's Manual of Determinative Bacteriology. Ninth Edition. Williamsand Wilkins. Baltimore, Maryland. 787 pp. 5. LINKS TO OTHER SITES ON NITROSOMONAS MicrobialEcology of the Nitrogen Cycle - A chapter from a Microbial Ecology courseat University of Waterloo in Canada. Behaviorand Physiology of Nitrifying Bacteria - publication by James E. Alleman,Ph.D. and Kurt Preston from the Scool of Civil Engineering at Purdue University. | HOMEPAGE| SYLLABUS| CHAPTERS| PROJECT| LINKS| | MICROBES| SOILS | CYCLES| APPLICATIONS|