Distribution of a consortium between unicellular algae and the N2 fixing cyanobacterium UCYN‐A in the North Atlantic Ocean. (17th April 2014)

• Record Type: Journal Article
• Authors: Krupke, Andreas; Lavik, Gaute; Halm, Hannah; Fuchs, Bernhard M.; Amann, Rudolf I.; Kuypers, Marcel M. M.
• Is Part Of: Environmental microbiology. Volume 16:Number 10(2014:Oct.)
• Page Start: 3153
• Page End: 3167
• Publication Date: 2014-04-17
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12431
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The globally abundant, uncultured unicellular cyanobacterium UCYN‐A was recently discovered living in association with a eukaryotic cell closely related to a prymnesiophyte. Here, we established a double CAtalysed Reporter Deposition‐Fluorescence <italic>In Situ</italic> Hybridization (CARD‐FISH) approach to identify both partners and provided quantitative information on their distribution and abundance across distinct water masses along a transect in the North Atlantic Ocean. The N<sub>2</sub> fixation activity coincided with the detection of UCYN‐A cells and was only observed in oligotrophic (< 0.067 <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh2cj9rxzv" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14622912:media:emi124318:emi12431-math-5001" display="inline" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="bold">N</mml:mi><mml:msubsup><mml:mi mathvariant="bold">O</mml:mi><mml:mn mathvariant="bold">3</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> μM and < 0.04 <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh2cj9rz3k" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14622912:media:emi124318:emi12431-math-5002" display="inline" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="bold">P</mml:mi><mml:msubsup><mml:mi mathvariant="bold">O</mml:mi><mml:mn mathvariant="bold">4</mml:mn><mml:mrow><mml:mn mathvariant="bold">3</mml:mn><mml:mo>−</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> μM) and warm (> 18°C) surface waters. Parallel 16S ribosomal RNA gene analyses among unicellular diazotrophs indicated that only UCYN‐A cells were present. UCYN‐A cells were associated with an algal partner or non‐associated using the double CARD‐FISH approach. We demonstrated that UCYN‐A cells living in association with <italic>H</italic><italic>aptophyta</italic> were the dominant form (87.0 ± 6.1%), whereas non‐associated UCYN‐A cells represented only a minor fraction (5.2 ± 3.9%). Interestingly, UCYN‐A cells were also detected living in association with unknown single‐celled eukaryotes in small amounts (7.8 ± 5.2%), presumably Alveolata. The proposed ecological niche of UCYN‐A as an oligotrophic, mesophilic and obligate symbiotic nitrogen‐fixing microorganism is evident for the North Atlantic Ocean.</p> </abstract>