Dr. Stephen Spiro

Professor and Head of the Department of Molecular and Cell Biology

C.L. and Amelia A. Lundell Professor of Life Sciences

Dr. Stephen Spiro’s research is focused on understanding the biological nitrogen cycle, especially the roles that microorganisms play in transforming inorganic nitrogen compounds.

He studies a biochemical pathway called denitrification, in which nitrate — a nitrogen atom combined with three oxygen atoms — is reduced to dinitrogen, which consists of just two nitrogen atoms. Denitrification is a source of the potent greenhouse gas nitrous oxide and is a route for the loss of fertilizer nitrogen from agricultural soils. On the beneficial side, denitrification can be exploited in treatment processes that remove nitrogen from sewage and wastewater.

In one step of the denitrification pathway, nitric oxide (NO) is made. This compound is a toxic molecule that is made as an intermediate or by-product of normal metabolism in microorganisms. It also plays an important role in the biology of higher organisms, including humans. For example, in response to infection with bacteria, fungi or viruses, cells of the mammalian immune system synthesize NO as a means of killing the invading pathogen.

“This is a kind of chemical warfare, in which some disease-causing organisms are able to fight back by removing the NO made by host cells,” Spiro said.

Spiro’s interest in denitrification led to his work on the NO detoxification mechanisms employed by pathogenic bacteria.

“There are interesting commonalities in the ways that environmental and pathogenic bacteria respond to and metabolize NO.”

Spiro joined the UT Dallas faculty in 2006 and was named head of the Department of Molecular and Cell Biology in 2011.

“I have always enjoyed teaching and take great satisfaction from helping students develop their understanding of difficult concepts in biochemistry and molecular biology,” Spiro said.

Spiro earned an undergraduate degree in molecular biology from the University of Edinburgh, and a doctoral degree in molecular biology and microbiology from the University of Sheffield, where he also completed a postdoctoral fellowship. Before joining UT Dallas, he held faculty positions at the University of East Anglia and at the Georgia Institute of Technology.

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Dr. Stephen Spiro

School of Natural Sciences
and Mathematics


Mr. and Mrs. C. L. Lundell established this chair on Dec. 1, 1978


Spiro joined the UT Dallas faculty in 2006 and was named head of the Department of Molecular and Cell Biology in 2011. “I have always enjoyed teaching and take great satisfaction from helping students to develop their understanding of difficult concepts in biochemistry and molecular biology,” he said.


“Despite the large growth in enrollment, UT Dallas retains many of the advantages of a smaller institution, in particular the opportunities for individual interactions with students. I like to give research experiences to undergraduate students and to train graduate students. Watching them go on to successful careers in their chosen domains is a source of great pleasure.”