Award: OCE-1657766

The incorporation of nitrogen gas into biology is a fundamental process that is biochemically complex and expensive, and yet is also biogeochemically essential on Earth. Trichodesmium is a keystone nitrogen fixing microbe in the oceans, and yet there is much to be learned about its ecology and biochemistry. In this study we explored Trichodesmium in the laboratory and natural environment using advanced techniques of proteomics and x-ray spectroscopy. Key findings included the observation that field populations of large colonies were co-stressed by iron and phosphate as indicated by protein biomarkers, rather than singly limited as ecology models generally predict. In addition, analysis of single colonies of Trichodesmium demonstrated that dust particles containing iron could be identified within them, and that those colonies had specific biochemical responses in their proteome to the mineral phase related to iron acquisition and within their microbiome community. Finally a diel study of Trichodesmium in the laboratory provided evidence for simultaneous C and N fixation and the production of gas vesicles, and these results were incorporated into a buoyancy model that demonstrated a need for daytime nitrogen fixation to overcome buoyancy challenges of large mineral-laden colonies. Additional projects supported by this grant, including the development of Metatryp 2.0 software for proteomics taxonomic inference, and a spin-off project was developed for COVID-19 assay research. Last Modified: 02/18/2021 Submitted by: Mak A Saito