Scientists coax shy microorganisms to stand out in a crowd

By Sandra Hines; News and Information

The communities of marine microorganisms that make up half the biomass in the oceans and are responsible for half the photosynthesis the world over, mostly remain enigmatic. A few abundant groups have had their genomes described, but the natures and functions of the rest remain mysterious.

Understanding how the changing global environment might affect these important ecosystem players is like trying to understand how the United States works when you can only discern Texas and California while many other states remain indistinct and you only suspect the existence of ones the size of Rhode Island and Delaware.

Now University of Washington scientists have advanced a method that allowed them to single out a marine microorganism and map its genome even though the organism made up less than 10 percent of a water sample teeming with many millions of individuals from dozens of identifiable groups of microbes

Typically researchers have had to isolate an organism and culture it in a lab before they could begin to crack its genome.

“We’ve done the opposite,” said Vaughn Iverson, a UW doctoral student in oceanography and lead author of a report in the Feb. 2 issue of the journal Science.

“We went to the environment, didn’t make any attempt to isolate any of the organisms in a laboratory sense and, instead, extracted the DNA from everything in the sample,” he said. “It’s a technique known as metagenomics. The UW’s innovation was to develop computational methods to simultaneously sequence all the parts and then reconstruct the chosen genome.”

 

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