Microbial Sulfur Metabolism

S-cycleThe overarching long-term goal of this project is to understand what gene products are required for the model phototrophic bacterium Chlorobaculum tepidum to harvest electrons from reduced sulfur compounds. In the larger scheme of things, the oxidation of reduced sulfur compounds, like the highly toxic compound hydrogen sulfide, is an important biogeochemical process that keeps the biosphere habitable for aerobes like humans.

C. tepidum is a strict anaerobe and an obligate phototroph that was originally isolated from volcanic hot spring sediments in New Zealand.  It is a member of the Chlorobi, the most low-light adapted phototrophic bacteria known.  It is a powerful model system for phototrophic microbes because it grows rapidly, it can utilize multiple reduced sulfur compounds, its genome sequence is complete and annotated, and it is genetically amenable.  These characteristics enable global "omics" analyses.  These types of analyses tell us how much of a given gene product is synthesized under specific growth conditions.  For genes that are unique to the Chlorobi or to C. tepidum, knowing when a protein or non-coding RNA is present in the cell is the first step to understanding what physiological processes it may be involved in.  From target lists developed in these "omics" experiments, we make mutants to prevent the synthesis of a protein or non-coding RNA or to produce an mutated version of the gene product and then analyze the ability of the resulting strain to grow and carry out its normal metabolism.  Really interesting targets can then be expressed and purified to further understand how they perform a particular function in vivo.

While this might seem a bit esoteric, the techniques used in analyzing C. tepidum are nearly identical to methods used to work with bacteria that cause disease, make biofuels, or that are more traditional model systems like Escherichia coli and Bacillus subtilis.  So, students and postdocs trained here can go on to work in almost any microbial system with the added advantage of having learned anaerobic culture techniques and analytical chemistry to identify and quantify various sulfur compounds.

Active Research Projects:

-Biogenic S(0) metabolism in a phototrophic bacterium (NSF-MCB-1244373).  This project is in collaboration with Clara Chan's group in Geological Sciences. We seek to understand molecular mechanisms that determine how the model phototrophic bacterium Chlorobaculum tepidum both forms and consumes insoluble inorganic S(0).  This project employs techniques ranging from microbial molecular genetics, transcriptomics, proteomics coupled with high-resolution imaging and elemental analysis methods.


Featured Faculty

Thomas Hanson

Thomas Hanson picture

Professor Marine Biosciences


CEOE School & Departments

School of Marine Science & Policy

Advancing the understanding, stewardship, and conservation of estuarine, coastal, and ocean environments.

Learn More
Department of Geological Sciences

Discovering how geological processes have operated over various time scales to create and influence the planet’s surface environments.

Learn More
Department of Geography

Investigating the interactions between people and the environment and the processes that explain the location of human and natural phenomena.

Learn More

College of Earth, Ocean, and Environment • 111 Robinson Hall • Newark, DE 19716 • USA • Phone: 302-831-2841
Geography: 302-831-2294 • Geology: 302-831-2569 • Marine Science and Policy: 302-645-4212 • E-mail: ceoe-info@udel.edu

Back to Top