This upcoming Thursday, University of Waterloo’s Dr. Josh Neufeld will talk on how
A perfect storm of scientific serendipity implicates Thaumarchaeota in global vitamin B12 production
at 12:30 in the EEB lounge (BioSciences 4338)
Vitamin B12 (cobalamin) is a complex metabolite and essential cofactor across many branches of life, including most aquatic algae. Eukaryotic algae and other cobalamin auxotrophs rely on environmental cobalamin supplied from a relatively small set of vitamin-producing prokaryotic taxa. Although several bacteria have been implicated in cobalamin biosynthesis and associated with algal symbiosis, the involvement of Archaea in cobalamin production is poorly understood; the Thaumarchaeota had not been implicated in cobalamin synthesis prior to this research. Based on the discovery of a complete thaumarchaeal cobalamin pathway in the metagenome of an aquarium biofilter, we hypothesized that Thaumarchaeota, which are ubiquitous and abundant in aquatic environments, play an important role in cobalamin biosynthesis within aquatic ecosystems. To test this hypothesis, we examined cobalamin synthesis genes across sequenced thaumarchaeal genomes and over 50 metagenomes from a diverse range of marine, freshwater, and hypersaline environments. Our analysis demonstrates that all available thaumarchaeal genomes possess cobalamin synthesis genes, predominantly from the anaerobic pathway, suggesting widespread genetic capacity for cobalamin synthesis. Furthermore, although bacterial cobalamin genes dominated most surface marine metagenomes, thaumarchaeal cobalamin genes dominated metagenomes from polar marine environments, increased with depth in the marine water column, and displayed a potential seasonality with increased winter abundance observed in time-series datasets (e.g., L4 surface water in the English Channel). Our results suggest niche partitioning between thaumarchaeal, euryarchaeal, proteobacterial, and cyanobacterial cobalamin genes across all metagenome datasets analyzed. Analyses of available soil metagenomes also implicate Thaumarchaeota as relatively abundant cobalamin producers in terrestrial habitats. These results provide strong evidence for specific biogeographical distributions of thaumarchaeal cobalamin synthesis genes, expanding our understanding of the global biogeochemical roles and keystone services provided by Thaumarchaeota.
Josh Neufeld is an Associate Professor in the Department of Biology at the University of Waterloo. As a microbial ecologist, Josh combines cultivation-based and molecular approaches for studying biogeochemical cycling in aquatic, terrestrial, and host-associated environments.
His website can be found here (https://uwaterloo.ca/biology/people-profiles/josh-d-neufeld) and he communicates via Twitter (@joshdneufeld).