Burning coal, oil and gasoline releases carbon dioxide as well as nitrogen dioxide into the atmosphere, where these industrial gases trap heat near the Earth's surface. To understand this 'greenhouse effect' and predict global warming, researchers must learn how carbon and nitrogen molecules cycle through the ocean--and that's easier said than done, says UD's David L. Kirchman, director of the Department of Marine Biology and Biochemistry within the College of Marine Studies.
So, Kirchman proposed an innovative way to investigate the break-down of carbon in coastal waters, by studying the degradation of chitin (pronounced KITE-un), a highly abundant, cellulose-like material generated by zooplankton, diatoms and other marine organisms.
On Oct. 2, the DOE applauded Kirchman's proposal, awarding him $366,000 to pursue it, in collaboration with David Royer, an associate professor of biology at Lincoln University.
The three-year grant was one of only 20 distributed by the DOE. "By tracking the fate of carbon and nitrogen in the ocean and studying its microbes, in some cases down to the molecular level, we hope to better understand the role of biology in global climate," explains Martha A. Krebs, director of the DOE's Office of Energy Research.
The UD/Lincoln project will provide new research opportunities for UD students at the undergraduate and graduate levels, Kirchman says. It also should bolster Lincoln University's emerging ecological and environmental programs. Lincoln, the oldest of the nation's historically black colleges and universities, has a long-standing reputation for excellence in the sciences. Now, the university is establishing a new program focusing on the environmental sciences, a field in which African-Americans have traditionally been under-represented.
When Royer learned of a DOE grant requiring the involvement of populations under-represented in marine sciences, he seized the opportunity. "Dr. Royer knew that I had received previous DOE awards to study carbon cycling in coastal waters, so he called me up," Kirchman says. "I was delighted, because the participation of Lincoln students and faculty will enrich the learning experience for UD students."
Chitin and Marine Biochemistry
The UD and Lincoln researchers will take a closer look at long-chain molecules generated by marine organisms such as Thalassiorsira and Skeletonema, two types of diatoms that crank out chitin strands for buoyancy. Diatoms are "major players in spring algae blooms," Kirchman notes.
How could chitin help reveal carbon's fate in the environment? When large quantities of chitin exist in coastal waters, Kirchman explains, certain marine bacteria kick into overdrive, producing more chitin-degrading enzymes, or chitinases. To extract nutrients from chitin, these bacteria use chitinases to "hydrolyze" or fragment large organic molecules into carbon and other component compounds small enough to cross cell membranes.
Smaller chitin fragments can then be "mineralized," or transformed into carbon dioxide. In this way, chitinases may prevent some carbon-containing chitin from sinking into deep-sea sediments. "Carbon buried deep beneath the sea may remain safely encapsulated for hundreds of years, and therefore doesn't contribute to global warming," Kirchman says. "Information about these enzymes may help us understand organic matter degradation in the ocean, which would be useful for predicting atmospheric carbon levels."
The researchers will investigate chitinases by measuring the genetic expression of the enzymes within a slow-growing marine bacterium. Enzyme synthesis should speed up or slow down to keep pace with bacterial growth rates, Kirchman says. He also plans to trigger a golden-brown algae bloom in the lab, by adding excess nutrients to water. Chock-full of chitin, the bloom should boost the abundance and expression of chitinase genes--and perhaps suggest how many sinking carbon-based particles are present within a given marine environment.
Kirchman and Royer will address fundamental questions about chitin and atmospheric carbon. In the future, the work also may suggest a way to develop better forms of cellulose, which is structurally similar to chitin and essential to the paper and textile industries. Marine chitinases might prove useful for fighting agricultural pests, too, since chitin is present in many crop-destroying insects and fungal pathogens. "It's possible," Kirchman says, "that these land-based pathogens and pests would be defenseless against a chitinase from a marine microbe."
For more information on UD's Department of Marine Biology and Biochemistry, please go to the World Wide Web site, http://www.udel.edu/cms/mbbfac.html