N2 fixation dominates nitrogen cycling in a mangrove fiddler crab holobiont

Autor: Mindaugas Zilius, Stefano Bonaglia, Elias Broman, Vitor Gonsalez Chiozzini, Aurelija Samuiloviene, Francisco J. A. Nascimento, Ulisse Cardini, Marco Bartoli
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Scientific Reports, Vol 10, Iss 1, Pp 1-14 (2020)
Druh dokumentu: article
ISSN: 2045-2322
DOI: 10.1038/s41598-020-70834-0
Popis: Abstract Mangrove forests are among the most productive and diverse ecosystems on the planet, despite limited nitrogen (N) availability. Under such conditions, animal-microbe associations (holobionts) are often key to ecosystem functioning. Here, we investigated the role of fiddler crabs and their carapace-associated microbial biofilm as hotspots of microbial N transformations and sources of N within the mangrove ecosystem. 16S rRNA gene and metagenomic sequencing provided evidence of a microbial biofilm dominated by Cyanobacteria, Alphaproteobacteria, Actinobacteria, and Bacteroidota with a community encoding both aerobic and anaerobic pathways of the N cycle. Dinitrogen (N2) fixation was among the most commonly predicted process. Net N fluxes between the biofilm-covered crabs and the water and microbial N transformation rates in suspended biofilm slurries portray these holobionts as a net N2 sink, with N2 fixation exceeding N losses, and as a significant source of ammonium and dissolved organic N to the surrounding environment. N stable isotope natural abundances of fiddler crab carapace-associated biofilms were within the range expected for fixed N, further suggesting active microbial N2 fixation. These results extend our knowledge on the diversity of invertebrate-microbe associations, and provide a clear example of how animal microbiota can mediate a plethora of essential biogeochemical processes in mangrove ecosystems.
Databáze: Directory of Open Access Journals
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