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  • Small but ver­sat­ile; key play­ers in the mar­ine ni­tro­gen cycle can util­ize cy­anate and urea

Small but ver­sat­ile; key play­ers in the mar­ine ni­tro­gen cycle can util­ize cy­anate and urea

Dec 10, 2018

The ammonia oxidizing archaea, or Thaumarchaeota, are amongst the most abundant marine microorganisms. Yet, we are still discovering which factors allow them to thrive in the ocean. A research team from the Max Planck Institute for Marine Microbiology in Bremen and the University of Vienna was now able to show that marine Thaumarchaeota have a broader metabolism than previously thought. The results are published in the journal Nature Microbiology.

The Thau­marchae­ota play a key role in the mar­ine ni­tro­gen cycle. They gain en­ergy for growth by con­vert­ing am­mo­nia, which is the most re­duced form of in­or­ganic ni­tro­gen, to a more ox­id­ized form: ni­trite. These so-called am­mo­nia ox­id­iz­ing ar­chaea were dis­covered little more than a dec­ade ago, yet these or­gan­isms make up a large part of the mar­ine mi­cro­bial com­munity, thriv­ing in the oceans des­pite am­monium be­ing present only at very low con­cen­tra­tions.

Even though the Thau­marchae­ota are such a key part of the mar­ine ni­tro­gen cycle, little is known about the physiology of these small and en­ig­matic mi­croor­gan­isms. In gen­eral, they are con­sidered to be meta­bol­ic­ally re­stric­ted, re­ly­ing on am­mo­nia as an en­ergy source. A new study by Kath­ar­ina Kitzinger and col­leagues from the Max Planck In­sti­tute for Mar­ine Mi­cro­bi­o­logy in Bre­men, Ger­many, the Uni­versity of Vi­enna, Aus­tria, the Geor­gia In­sti­tute for Tech­no­logy, USA, the Carl von Os­si­et­zky Uni­versity Olden­burg, Ger­many, and the Uni­versity of Bre­men, Ger­many, now re­veals that this is not quite true. Rather, the au­thors show that mar­ine am­mo­nia ox­id­iz­ing ar­chaea can also util­ize or­ganic ni­tro­gen sources.

Figure caption 1: Single-cell images of environmental marine ammonia oxidizing archaea. Panel (a) identifies the ammonia oxidizing archaea (green) and surrounding cells (blue), panel (b) reveals their uptake of cyanate. This can be determined with NanoSIMS, a technology that provides highly detailed insights into the activity of single cells. Ammonia oxidizing archaea are marked by white outlines. Scale bar is 1 μm. (Copyright: Max Planck Institute for Marine Microbiology/K. Kitzinger)  Figure caption 2: Samples for this study were taken in den Gulf of Mexico. (Copyright: Max Planck Institute for Marine Microbiology/K. Kitzinger)
Figure caption 1: Single-cell images of environmental marine ammonia oxidizing archaea. Panel (a) identifies the ammonia oxidizing archaea (green) and surrounding cells (blue), panel (b) reveals their uptake of cyanate. This can be determined with NanoSIMS, a technology that provides highly detailed insights into the activity of single cells. Ammonia oxidizing archaea are marked by white outlines. Scale bar is 1 μm. (© Max Planck Institute for Marine Microbiology/K. Kitzinger)

“We show for the first time that both en­vir­on­mental and cul­tured mar­ine am­mo­nia ox­id­iz­ing ar­chaea can use cy­anate, a simple or­ganic ni­tro­gen com­pound, as an ad­di­tional en­ergy source“, Kitzinger ex­plains. Fur­ther, they show these mi­croor­gan­isms also use that urea, an­other or­ganic ni­tro­gen com­pound. These find­ings are im­port­ant as cy­anate and urea are com­mon ni­tro­gen and en­ergy sources in the oceans. The Thau­marchae­ota’s abil­ity to sup­ple­ment their meta­bol­ism with these com­pounds might be one reason for their out­stand­ing suc­cess in the oceans.   

Kitzinger is es­pe­cially in­trigued by how the mar­ine am­mo­nia ox­id­iz­ing ar­chaea are able to use cy­anate. “We still aren’t sure ex­actly how they do it. They don't have the typ­ical en­zyme rep­er­toire needed to use cy­anate. It will be ex­cit­ing to see which en­zymes al­low mar­ine am­mo­nia ox­id­iz­ing ar­chaea to use cy­anate, if these or­gan­isms have an even lar­ger meta­bolic ver­sat­il­ity than we know now, and how this ver­sat­il­ity shapes their eco­logy”, says Kitzinger.

Figure caption 2: Samples for this study were taken in den Gulf of Mexico. (Copyright: Max Planck Institute for Marine Microbiology/K. Kitzinger)
Figure caption 2: Samples for this study were taken in den Gulf of Mexico. (copyright: Max Planck Institute for Marine Microbiology/K. Kitzinger)

Ori­ginal pub­lic­a­tion

Kath­ar­ina Kitzinger, Cory C. Pa­dilla, Han­nah K. Marchant, Phil­ipp F. Hach, Craig W. Herbold, Abiel T. Kid­ane, Mar­tin Kön­neke, Sten Littmann, Maria Moosham­mer, Jutta Nigge­mann, Sandra Pet­rov, An­dreas Richter, Frank J. Stew­art, Mi­chael Wag­ner, Mar­cel M. M. Kuypers, Laura A. Bris­tow: Cy­anate and Urea are Sub­strates for Ni­tri­fic­a­tion by Thau­marchae­ota in the Mar­ine En­vir­on­ment. Nature Mi­cro­bi­o­logy.

DOI: 10.1038/s41564-018-0316-2

Par­ti­cip­at­ing in­sti­tutes

  • Max Planck In­sti­tute for Mar­ine Mi­cro­bi­o­logy, Bre­men, Ger­many

  • De­part­ment of Mi­cro­bi­o­logy and Eco­sys­tem Sci­ence, Uni­versity of Vi­enna, Aus­tria

  • School of Bio­lo­gical Sci­ences, Geor­gia In­sti­tute of Tech­no­logy, At­lanta, USA

  • Re­search Group for Mar­ine Geo­chem­istry (ICBM-MPI Bridging Group), In­sti­tute for Chem­istry and Bio­logy of the Mar­ine En­vir­on­ment, Carl von Os­si­et­zky Uni­versity, Olden­burg, Ger­many

  • Mar­ine Ar­chaea Group, MARUM – Cen­ter for Mar­ine En­vir­on­mental Sci­ences, Bre­men, Ger­many

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Dr. Hannah Marchant

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Dr. Hannah Marchant

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Dr. Fanni Aspetsberger
 
 
 
 
 
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