Microbes are the oldest and most numerous organisms in the world -- so how do you even begin to study what they do and how they do it? Start with two Cornell experts, 20 advanced students and six weeks on Cape Cod to collect, isolate and identify novel microbes.

This past summer, Dan Buckley, professor of crop and soil sciences, and Steve Zinder, professor of microbiology, led an intensive summer course, Microbial Diversity, at the Woods Hole Oceanographic Institute.

"The goal was to give a fundamental background in microbial diversity and ecology and to focus on understanding how to characterize microorganisms in the environment," said Buckley.

The students were a select group of graduate students and postdoctoral researchers who "came from different backgrounds, from microbiologists to chemists to astrobiologists; some were well-versed in microbiology and some weren't," Zinder said.

After two weeks of introductory lectures, students delved into independent research projects. They sampled from several environments around Woods Hole, including saltwater, freshwater, a cranberry bog, even the wastewater treatment plant, and then enriched and isolated bacteria that had properties they wished to study.

"One student, a chemist, was really interested in natural product synthesis, so she isolated a red bacterium and then isolated the compound that made it red," said Heather Fullerton, a Cornell microbiology graduate student and the course coordinator. The compound, she said, is likely involved in chemical reactions that may be unique to this species.

Another highlight of the course was bringing in about 30 lecturers from all over the world, including leaders in microbiology, said Buckley.

The course has been running since 1971, but this year marked the first of five years that Buckley and Zinder were the directors and also the first time both course directors came from the same university. That does not surprise Zinder. "Cornell is one of the leading institutions for studying microbial diversity," he said.

In the next four years, they hope to shift the focus of the course to studying single microbes. "By studying at the level of individual cells in the environment, we can learn what microbes are capable of doing versus what they're actually doing," Buckley said.

But by no means is the diversity in the microbial world fully understood. In one of the enrichment cultures that Zinder has brought back to his lab from Woods Hole are purple photosynthetic bacteria that have aggregated into multicellular clumps they call "crunch berries." What are those bacteria, and what purpose do the aggregates serve? "We don't know," he said.

Graduate student Sarah Perdue is a science writer intern for the Chronicle.