Roxana Shafiee

Roxana Shafiee

Postgraduate

Nitrogen is the basis of life as we know it  – forming a major component of DNA, protein and nucleic acids. It therefore follows that nitrogen availability influences rates of primary productivity in the modern and ancient oceans, holding implications for global climate.  The global cycling of nitrogen is mediated by microorganisms,  invisible to the naked eye, which inhabit every corner of the Earth. The factors which drive the distribution and growth of these key microorganisms in the modern oceans remain elusive – yet is central to clarifying how such microbes have evolved over geologic time and how they may respond in an ocean perturbed by anthropogenic activity.

My research focuses on the microbes which perform the main, rate limiting oxidative step of the N-cycle – ammonia-oxidation to nitrite. We understand very little about how fine-tuned these microorganisms are to their chemical environment, in particular how sensitive they are to changes in trace metals. Specifically, I cultivate the recently discovered globally abundant archaeon Nitrosopumilus maritimus in the laboratory and use a combination of methods, including metallo-proteomics and trace metal clean techniques,  to build an understanding of their metal requirements. I am part of the APPELS research project within the Oxford OceanBug group, led by Professor Rosalind Rickaby,  which aims to shed light on the full metal requirements of phytoplankton, but have expanded the scope to include other dominant marine microorganisms.