Predominant heterotrophic diazotrophic bacteria are involved in Sargassum proliferation in the great Atlantic Sargassum Belt
Type | Article | ||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Date | 2024-01 | ||||||||||||||||||||||||||||
Language | English | ||||||||||||||||||||||||||||
Author(s) | Léger-Pigout M1, Navarro E1, Menard F1, Ruitton S1, Le Loch Francois2, Guasco S1, Munaron Jean-Marie2, Thibault D1, Changeux T1, Connan S2, Stiger-Pouvreau V3, Thibaut T1, Michotey V1 | ||||||||||||||||||||||||||||
Affiliation(s) | 1 : Aix Marseille Univ, Université de Toulon , CNRS, IRD, MIO, 13288 Marseille, France 2 : Univ Brest, CNRS, IRD, Ifremer, LEMAR , F-29280, Plouzane, France 3 : Univ Brest, CNRS, IRD, Ifremer, LEMAR , F-29280, Plouzane, France |
||||||||||||||||||||||||||||
Source | Isme Journal (1751-7362) (Oxford University Press (OUP)), 2024-01 , Vol. 18 , N. 1 , P. wrad026 (9p.) | ||||||||||||||||||||||||||||
DOI | 10.1093/ismejo/wrad026 | ||||||||||||||||||||||||||||
Keyword(s) | Sargassum, N2 fixation, nitrification, denitrification, GASB, isotopy, Vibrio spp | ||||||||||||||||||||||||||||
Abstract | Since 2011, the Caribbean coasts have been subject to episodic influxes of floating Sargassum seaweed of unprecedented magnitude originating from a new area “the Great Atlantic Sargassum Belt” (GASB), leading in episodic influxes and mass strandings of floating Sargassum. For the biofilm of both holopelagic and benthic Sargassum as well as in the surrounding waters, we characterized the main functional groups involved in the microbial nitrogen cycle. The abundance of genes representing nitrogen fixation (nifH), nitrification (amoA) and denitrification (nosZ) showed the predominance of diazotrophs, particularly within the GASB and the Sargasso Sea. In both location, the biofilm associated with holopelagic Sargassum harboured a more abundant proportion of diazotrophs than the surrounding water. The mean δ15N value of the GASB seaweed was very negative (−2.04‰), and lower than previously reported, reinforcing the hypothesis that the source of nitrogen comes from the nitrogen-fixing activity of diazotrophs within this new area of proliferation. Analysis of the diversity of diazotrophic communities revealed for the first time the predominance of heterotrophic diazotrophic bacteria belonging to the phylum Proteobacteria in holopelagic Sargassum biofilms. The nifH sequences belonging to Vibrio genus (Gammaproteobacteria) and Filomicrobium sp. (Alphaproteobacteria) were the most abundant and reached respectively up to 46.0% and 33.2% of the community. We highlighted the atmospheric origin of the nitrogen used during the growth of holopelagic Sargassum within the GASB and a contribution of heterotrophic nitrogen-fixing bacteria to a part of the Sargassum proliferation. |
||||||||||||||||||||||||||||
Licence | |||||||||||||||||||||||||||||
Full Text |
|