Bacterias in Cycling

[Rohanz21]

Hello everyone. I was reading some articles on cycling and came to know that the cycling starts with Nitrogen fixation where atmospheric nitrogen is fixed biologically to ammonia in water with the help of Cyanobacteria. Does this really happen in your aquarium?

Also i read an research article where its specified that it was believed that Nitrobacter oxidized Nitrite to Nitrate but research showed the presence of Nitrospira Bacteria instead of Nitrobacter which is found negligible in aquarium. Is this true?

[Paul G]

1.) Nitrogen-fixation, denitrification, and nitrification are three different processes.

Nitrogen-fixation is a process wherein soil bacteria convert atmospheric nitrogen into nitrate, which becomes available to plants through the roots. Other soil bacteria called denitrifiers can do the opposite, converting nitrate in the soil into nitrogen which is then lost to the atmosphere. This process occurs when there is poor oxygenation of the soil.

These processes are part of the over-all nitrogen cycle in nature, but are not significant players in what the aquarium hobby calls "cycling". This usually refers to the nitrification process wherein ammonia is converted to nitrite then to nitrate. In healthy well-oxygenated aquariums, this is a one-way process, and the nitrate will eventually concentrate in the system. Plants in aquariums require nitrogen and can use nitrate, thus completing the full cycle. Denitrification is a subject that can be of interest to planted aquarium enthusiasts, but not so much nitrogen-fixation. Aquatic plants have no known means of using atmospheric nitrogen directly.

Cyanobacteria are photosynthesizing bacteria, sometimes called blue-green algae. Various species occur in the aquarium under certain circumstances. They don't play an especially significant role in any of these processes.

2.) Dr Timothy Hovanec has shown that the nitrifiers responsible for conversion of nitrite to nitrate in the aquarium are mostly in genus Nitrospira, rather than in genus Nitrobacter, a common nitrifier in soils. Dr Tim and colleagues have done research into the microbiology of organisms that are important to biological filtration.

[Tom Barr]

It happens for certain with Anabena in Azolla, otherwise I'd say it's non significant since most all of the plants and such we keep have enough N, unless we purposefully, or neglectfully do not add enough N.

[Rohanz21]

@ Paul G

I came to know this from the article of Dr.Tim only

@ Paul G and Tom

Do you all agree with this that its actually Nitrospira instead of Nitrobacter or have made any research on these? Am very eager to know

[Rohanz21]

That means in our aquarium the fixation by bacteria is negligible except in Azolla?

[Paul G]

The Azolla / Anabaena symbiosis is an interesting exception. I looked in my reference by Jiri Stodola, and he refers to the bacterial component as being highly specific, Anabaena azollae. Does this symbiosis require that it be a floating plant?

I amend my sweeping generalization: I would say that nitrogen-fixation is not a significant process in aquatic plants. As Tom points out, nitrogen is normally freely available from other sources in aquatic environments.

As far as I know, the Hovanec findings are valid. I would be interested to know if the science is changing on this front.

It should be said that biological filters are complex communities of various species populations working together. The presence of and contribution by any one type in any one filter at any one time can never be precisely known. There could well be more than one type performing the same biochemical process.

Regards, Paul G

[Rohanz21]

Thanks for the infos Paul G.

I will be taking bacteria samples from two matured filter media to the city's Microbiology Lab and get them test for bacterial count and type recognition.Lets see what are the results.

[Biollante]

Hi,

Any results?


Biollante