# Good review article on ammonia oxidation



## dw1305 (17 Jun 2019)

Hi all,
Definitely a <"dead donkey"> of a thread title, but if any-one is interested there is a good open-source review article on the microbial mechanisms for nitrification, it is the science behind the cycling discussion in <"Bedside Aquarium">:

Laura E Lehtovirta-Morley <"Ammonia oxidation: Ecology, physiology, biochemistry and why they must all come together"> _FEMS Microbiology Letters_, Volume *365*, Issue 9, May 2018. The author works at <"UEA in Norwich">. 





> ....AOA vastly outnumber AOB in most soil and aquatic environments, often by orders of magnitude (Leininger _et al._2006). It is estimated that there are 1 × 10^28 AOA cells in the Earth's oceans and they are some of the most numerous living organisms on Earth, accounting for up to 40% of all prokaryotes in marine ecosystems and 1%–5% in terrestrial ecosystems (Karner, DeLong and Karl 2001; Leininger _et al._2006). In contrast, AOB usually dominate numerically over AOA in wastewater treatment plants and occasionally in fertilised soils (Bates _et al._2011; Mussmann _et al._2011). Little is known about the abundance and diversity of comammox _Nitrospira_, although their abundance has been reported to be comparable to, or higher than the abundance of other ammonia oxidisers.......





> ....The notion that ammonia oxidation is problematic at low pH was overturned by the discovery of the first obligately acidophilic ammonia oxidiser, _N. devanaterra_ (Lehtovirta-Morley _et al._2011). Originally isolated from an acidic agricultural soil, this archaeon grows autotrophically in the pH range of 4–5.5 in laboratory culture with ammonium chloride as its sole energy source. Although _Nitrosotalea_ is the only obligately acidophilic ammonia oxidiser described to date, it is unlikely to be the only microorganism performing nitrification in acidic soils......





> .........The kinetic theory of the optimal pathway length suggested that the comammox process would lead to a higher yield but lower growth rate than incomplete ammonia oxidation, giving comammox organisms a competitive advantage when ammonia concentration is low (Costa, Pérez and Kreft 2006). It is interesting to note that the half-saturation constants of many AOA and comammox are roughly within the same range.


Cheers Darrel


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## JMorgan (27 Oct 2019)

Thank you for the precis Darrel - and for your many other posts over the years and more recently on the 'bedside' thread you linked to above. I've been extremely busy the last few months, my aquariums have been receiving minimum maintenance rather than my being actively engaged with them. That they've been able to be mildly neglected without catastrophe has been largely due to the reasonably solid understandings I've gained from reading your posts - since I don't run any high light or hi tech aquaria, Floating plants, emergent growth, and just generally having them set up with available oxygen being the top priority has kept everything ticking along with minimal fuss.
Thanks from my fish too!


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## dw1305 (27 Oct 2019)

Hi all,





JMorgan said:


> .......receiving minimum maintenance rather than my being actively engaged with them. That they've been able to be mildly neglected without catastrophe .....Floating plants, emergent growth, and just generally having them set up with available oxygen being the top priority has kept everything ticking along with minimal fuss.


I'm pleased its helped, it is a <"KISS solution">. You just  cut out any <"single points of failure">, and have as many negative feedback loops as possible. 





JMorgan said:


> has been largely due to the reasonably solid understandings I've gained from reading your posts.


I've learnt a lot as well from posting on UKAPS. I was pretty sure that a lot of the conclusions I'd made were right, but I didn't have the scientific references, or a suitable lab., to actually under-pin a lot of it. 

When I started making the "cycling" posts I didn't really have any scientific argument for why you didn't need to add ammonia to cycle the tank etc. and it made it a lot easier for people to rubbish the conclusions. I knew a fair bit about phytoremediation, and I knew that it worked, but I didn't know anything about the microbial side of plant/microbe filtration. 

I was sure that the linear view of cycling wasn't the full story, but it was only with the new research (using the DNA libraries) that it became apparent just how different things were.

cheers Darrel


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