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Research Overview
Research Overview
The Sosa Lab is interested in the biochemical and geochemical functions mediated by microbial plankton communities in the ocean. Our research applies a synergistic approach of microbiology, metagenomics, and genetics in the laboratory and oceanographic and biogeochemical field studies to understand how these functions impact nutrient cycling, carbon flow, and the ecology of microbes in the sea. Of special interest to our group are microbial functions that produce methane and cycle phosphorus in marine surface waters.
The Sosa Lab is interested in the biochemical and geochemical functions mediated by microbial plankton communities in the ocean. Our research applies a synergistic approach of microbiology, metagenomics, and genetics in the laboratory and oceanographic and biogeochemical field studies to understand how these functions impact nutrient cycling, carbon flow, and the ecology of microbes in the sea. Of special interest to our group are microbial functions that produce methane and cycle phosphorus in marine surface waters.
Methane in the Sargasso Sea
Methane in the Sargasso Sea
The Sargasso Sea is an oligotrophic oceanic ecosystem with surface waters supersaturated with methane. This observation indicates that biological processes contribute to natural methane emissions in the region. Recent studies indicate that phosphate depletion in this ecosystem selects bacterial populations with C-P lyase, an enzyme implicated in methanogenesis through the demethylation of the compound methylphosphonate. In collaboration with the Bermuda Institute of Ocean Sciences (BIOS), we will investigate the seasonal variability of dissolved methane in the Sargasso Sea by conducting measurements at the Bermuda Atlantic Time-series Study (BATS) site. We hypothesize that methane saturation levels in the upper ocean vary seasonally in response to the availability of phosphate. Through this project, students from the University of Puget Sound will have the opportunity to participate in oceanographic research cruises and develop independent projects in the lab. This research is possible with the generous support of the M.J. Murdock Charitable Trust.Â
Microbial Cycling of Organic Matter
Microbial Cycling of Organic Matter
Microbial plankton communities in the ocean produce, exchange, and break down millions of organic compounds on a dialy basis. We use genetics, sequencing, and microbial model systems to identify the enzymes and metabolic pathways that mediate the cycling of organic compounds used as nutrients by bacteria.
Phosphonates
Phosphonates
Methylphosphonate is a methane precursor and an abundant source of phosphorus in the ocean. Under phosphate stress, bacteria containing the enzyme C-P lyase enzyme break down methylphosphonate to obtain phosphorus. This reaction releases methane as byproduct and is hypothesized to explain the marine methane paradox - the ubiquitous over-saturation of methane in the oceanic water column. In turn, organisms like the marine photosynthetic cyanobacterium Prochlorococcus contain an oxidative pathway that breaks down methylphosphonate into formate and phosphate.
Homarine
Homarine
Small polar nitrogenous metabolites like homarine are common chemical currencies in the marine pelagic environment. In collaboration with the Ingalls Lab at the University of Washington, we are dissecting the genes and biochemical pathways marine bacteria use to consume homarine.
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