Nitrospira can live in marine or nonmarine habitats. It has been isolated from ocean water, freshwater, aquarium water, deltaic sediment, deep-sea sediments, soils, and an iron pipe of a heating system (Daims
et al. 2001).
Nitrospira is part of a nitrification process which is important in the biogeochemical
nitrogen cycle. Nitrification is the oxidation of ammonia to nitrite by autotrophic bacteria of the genus
Nitrosomonas and oxidation of the nitrite to nitrate by bacteria in the genus
Nitrobacter or
Nitrospira. This is important in marine environments because too much ammonia or nitrite can cause death in fish. However,
Nitrospira and similar bacteria are slow-growing organisms, which means that a newly set-up aquarium without an established population of these bacteria can accumulate toxic concentrations of ammonia and nitrite. In an attempt to fix this problem, commercial companies have tried to market special preparations of ammonia-oxidizing and nitrite-oxidizing bacteria (the mixes included
Nitrobacter instead of
Nitrospira) that could be put into a new aquarium to establish a healthy nitrogen cycle. However, these mixes were inexplicably ineffective so tests were done to analyze the bacterial content of aquaria water. While bacteria from the genus
Nitrobacter are nitrite-oxidizing organisms and could theoretically fill the nitrite-oxidizing niche, the tests indicated relatively high numbers of
Nitrospira and no
Nitrobacter bacteria at all. Thus,
Nitrospira is now considered the dominate nitrite-oxidizing bacterium in aquariums, (as well as in wastewater treatment systems and other reactors as shown by other similar studies) (Hovanec
et al.1998). Though water that is too rich in ammonia or has a pH that is too low will inhibit
Nitrospira's nitrifying activity.
Check the Kirschman "Microbial Ecology of the Oceans" book. There are differences, especially in the physiology of the bacteria under particular circumstances, but there are many many more similarities, and a realistic and accurate response is prolly beyond the scope of a good answer in this thread. Some bacteria will live in both fresh and SW environments, a few will not live in either fresh or marine environments when they come from the opposite, and the more this is investigated as part of the bacterial genome projects, the more that comes out about what we do not know or are totally unaware of entire families in the Ocean's microecologies.
Also check the Brock Microbiology book, there is a whole chapter dedicated to this topic, the newest (11th edition) goes into some of the use of Sub ribosomal unit seaerches for species of bacteria that have yet to be cultured in the lab, but are being phylogenically classified as we speak. Interestingly enough, procaryotic kingdoms have different distribution profiles based on depth, with Archaea (primarily
Crenachaeota spp ) dominating depths below 1000 meters, and species of Bacteria dominating the upper layers and photoautotropohs (eucaryotic algae and Prochlorophytes//Cyanobacteria) occupying the very top layers of the ocean.primary habitats include the surface open ocean, peliagic open ocean below the photozone, deep-see ocean hydrothermal vent biotopes, soft substrates, and a few hypersaline environments that are strictly marine, although there are a few select highly specialized environments as well
