Alteromonas is a genus of cosmopolitan copiotrophic marine bacteria that associate with particles and are capable of metabolizing a large suite of carbon substrates. We aim to describe and understand patterns of niche partitioning underlying the metabolic diversity of this genus, and in particular to identify the drivers of metabolic innovations within Alteromonas. To this end we gathered 78 isolate genomes and 258 metagenome-assembled genomes of Alteromonas, assembled them into a pangenome and created a phylogeny from evolutionarily relevant single copy core genes. We then surveyed the leaves of this tree for the presence and absence of genes involved in core carbon metabolism, with a focus on carbon cycling and substrate degradation. Among genes involved in polysaccharide degradation, we find those for using alginate and pectin are patchily distributed across clades while those forusing laminarin are highly conserved. We also find diversity in the distribution of genes for the glyoxylate shunt and fatty acid and amino acid catabolism genes. Together these observations are beginning to illuminate the metabolic niche dimensions of Alteromonas. Finally, we find that depth of isolation or metagenome sampling correlates with clade structure and metabolic strategies, suggesting depth-based changes in particle composition may play a role in driving niche partitioning. More generally, this work deepens our understanding of the metabolic diversification of Alteromonas throughout its evolution and identifies forces that continue to shape the flow of carbon in extant marine systems.

Primary Presenter: Michelle DeMers, Massachusetts Institute of Technology (mademers2018@gmail.com)

Authors:

Michelle DeMers, Massachusetts Institute of Technology  (demers@mit.edu)

Rogier Braakman, Massachusetts Institute of Technology  (braakman@mit.edu)