The production of hydroxylamine (NH2OH) during bacterial and archaeal nitrification.

Martogli, Natascha (2012) The production of hydroxylamine (NH2OH) during bacterial and archaeal nitrification. (Diploma thesis), Christian-Albrechts-Universität Kiel, Kiel, Germany, 90 pp.

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Hydroxylamine as an intermediate during bacterial nitrification has been well-known for a long time. Archaeal nitrification on the other hand was identified only seven years ago, isolating a marine archeon from a seawater- quarium in Seattle, USA. Hence, the process of archaeal ammonium oxidation and, therefore, the involvement of hydroxylamine as a possible intermediate product still are only understood poorly, as until today only the archaeal ammonium monooxygenase has been found, but not the second enzyme which is responsible for the oxidation of hydroxylamine to nitrite in bacteria. The aim of this thesis was to investigate hydroxylamine as a possible intermediate product of archaeal ammonium oxidation and to determine a possible influence of fertilization with ammonia on the production of hydroxylamine. For this purpose different incubation experiments were conducted using environmental samples as well as pure cultures of the archeon Nitrosopumilus maritimus and two different bacterial strains, namely Nitrosomonas marina and Nitrosococcus oceani. The experiments with environmental samples all showed a clear effect of ammonium chloride as a fertilizer, stimulating hydroxylamine roduction. Also a temperature effect was observed, as the samples incubated at 30°C showed a higher production of hydroxylamine than the samples, which were incubated at 12°C, the insitu temperature when the samples were taken. Experiments with two different inhibitors showed, that the hydroxylamine production in unfertilized samples incubated at 30 °C was dominated by archaea. These results serve as a first evidence of archaeal ydroxylamine production and were confirmed by the incubations done with pure culture. The incubations of pure cultures clearly indicated a hydroxylamine production in all used strains, nevertheless differing between bacterial and archaeal production. They showed that the bacterial potential to produce hydroxylamine is considerably higher in bacterial pure cultures than in environmental samples, in which nearly no production of hydroxylamine by bacteria was
traceable. The archeon Nitrosopumilus maritimus on the other hand also in pure culture produced only small amounts of hydroxylamine. This corresponds also to the hydroxylamine concentrations produced by ammonium oxidizing archaea found in environmental samples. Nevertheless, a production of hydroxylamine was detectable and confirms the assumption of
hydroxylamine as an intermediate also during archaeal ammonium oxidation. This conclusion not only implicates the possibility to lucidate the process of ammonium oxidation further, but
also that hydroxylamine can be used as an indicator of active nitrification in the oceans.

Document Type: Thesis (Diploma thesis)
Keywords: Hydroxylamine, NH2OH, Nitrification, Boknis Eck
Research affiliation: OceanRep > SFB 754 > B4
Kiel University
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
Projects: Boknis Eck, SFB754
Date Deposited: 13 Nov 2012 09:45
Last Modified: 23 Sep 2019 20:58

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