We applied a suite of oligonucleotide probes to verify the compatibility of the different steps of our protocol with CARD-FISH and concomitantly to provide a first overview of the application of the method. At both sites, 83–90% of DAPI cells were EUB
positive. Of the DAPI cells associated with silver grains, 83–100% of them were also EUB positive. By contrast, the fraction of cells that hybridized with the control probe remained low (< 1% of DAPI cells). We determined that the relative contribution of the bacterial groups Inhibitor Library purchase to total 55Fe-incorporating cells was reflected in their respective contributions to abundance (Fig. 4). The percent DAPI cells with visible silver grains were overall low for both experiments, this pattern could therefore reflect the most active iron-incorporating cells. It was, however, interesting to note that the contributions of Gammaproteobacteria, SAR86 and Alteromonas to 55Fe uptake were higher than their respective contributions to abundance. Members of the Gammaproteobacteria are frequently reported to develop in incubation experiments due to their opportunistic lifestyle. Even though we did not observe any major changes in the relative abundance of the Pirfenidone bacterial groups over the 7 days of incubation time (Fig. S1), this group could have strategies to efficiently respond to the iron addition. Alternatively, it
is also possible that members of the Gammaproteobacteria have higher iron cell quota. Additional work should aim to address these issues further. Thus, despite the contrasting
environmental conditions at the two study sites, we observed a similar pattern in the response of the bacterial community to iron uptake. To the best of our knowledge, our study provides the first description of the bacterial community, on different phylogenetic levels, that contributes to iron uptake in different ocean regimes. Taken together, the method described here demonstrates that MICRO-CARD-FISH using the radiotracer 55Fe can be successfully applied to the study of marine bacterial groups involved in iron uptake. Our study highlights the potential of the method Tyrosine-protein kinase BLK in future studies. A promising application would be to investigate iron bound to various organic ligands, which could provide insights into the capability of heterotrophic bacteria to acquire iron from different sources. We thank Matthew Cottrell for invaluable advice in image analysis processing. We thank the constructive comments of two anonymous reviewers and the editor that helped improve a previous version of the manuscript. This work was funded by Agence Nationale de la Recherche (Project BACCIO, Biomolecular Approach of the Cycling of Carbon and Iron in the Ocean, ANR-08-BLAN-0 309). “
“An isolated Serratia marcescens strain exhibited growth-coupled perchlorate () reduction under anoxic conditions. Perchlorate was reduced completely with stoichiometric chloride buildup and equimolar acetate consumption.