Authors:Fernando Puente-Sánchez, Luis Macías, Karley L. Campbell, Marta Royo, Vanessa Balagué, Pablo Sánchez, Javier Tamames, C.J. Mundy, Carlos Pedrós-Alió
- Department of Systems Biology, Centro Nacional de Biotecnología, CSIC, Darwin 3, 28064 Madrid, Spain
- Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB, Canada
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar, CSIC, Ps. Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain
Date: February 2022
Microbial assemblages under sea ice of Dease Strait, Canadian Arctic, were sequenced for metagenomes and metatranscriptomes of the small size fraction (0.2 to 3 µm). The community from early March was typical for this season, with Alpha– and Gammaproteobacteria as the dominant taxa, followed by Thaumarchaeota and Bacteroidetes. Towards summer, Bacteroidetes and particularly the genus Polaribacter, became increasingly dominant, followed by the Gammaproteobacteria. Analysis of genes responsible for microbial acquisition of iron showed an abundance of ABC transporters for divalent cations and ferrous iron. The most abundant transporters, however, were the outer membrane TonB dependent transporters of iron-siderophore complexes. The abundance of iron acquisition genes suggested this element was essential for the microbial assemblage. Interestingly, Gammaproteobacteria were responsible for most of the siderophore synthesis genes. On the contrary, Bacteroidetes did not synthesize siderophores but accounted for most of the transporters, suggesting a role as cheaters in the competition for siderophores as public goods. Likely, this cheating ability of the Bacteroidetes contributed to their dominance in summer.