We employed metagenome-assembled genomics to successfully obtain 24 good quality MAGs ranging from (54-92%) in completeness with considerably low contamination levels (<10%) across samples from 2-92 meters below seafloor from the IODP Expedition 334 in the Costa Rican margin. Interestingly, the taxonomic assignments of 3 MAGs belonged to a novel bacterial phylum as supported by both GTDB-tk and ribosomal protein based analyses. Differential coverage analysis of the recovered MAGs across CR datasets indicated that this novel phylum was the most abundant in the deepest parts of the cores at both Site U1378 and U1379, down to 92 meters below seafloor. The collective metabolic reconstruction of this novel phylum indicated the presence of hydrogenic capacities using diverse groups of FeFe, NiFe and NiFeSe hydrogenases. Detailed metabolic reconstruction of the MAGs indicated the presence of genes encoding for anaerobic processing of benthic gasses, in particular hydrogen, to create a proton motive force fueling their ATP synthase to yield energy as well as carbon-dioxide fixation pathways, especially the Wood-Ljungdahl pathway. We hypothesize that this bacteria cross-feeds neighboring microbes due to the presence of a large number of secondary metabolites and co-factors biosynthetic genes, as well as macromolecule biosynthetic pathways, coupled with a large set of transporters and secretory proteins. This novel subsurface-specific phylum most likely plays a role in recycling hydrogen from both geologic or biologic sources and sharing metabolites with the neighboring microbes.  

Primary Presenter: Jacob Williams, Temple University (jacobwilliams6958@gmail.com)

Authors:

Ibrahim Farag, University of Delaware  (faragif@udel.edu)

Jacob Williams, Temple University  (jacobwilliams6958@gmail.com)

Elham Badiea, Ain Shams University  (ebadiea@aucegypt.edu)

Jennifer Biddle, University of Delaware  (jfbiddle@udel.edu)