First harmful algal bloom species genome sequenced

Tuesday, February 22, 2011

WASHINGTON - A team of researchers including U. S. Department of Energy (DOE) Joint Genome Institute (JGI) scientists led by Igor Grigoriev has successfully completed and annotated the first genome sequence of a (harmful algal bloom) HAB species: Aureococcus anophagefferens.

Algae play key roles in the global carbon cycle, sometimes helping sequester significant amounts of carbon but can also turn the ocean waters brown or green and disrupt an ecosystem.

When billions of Aureococcus cells come together, they outcompete the other marine phytoplankton in the area, damaging the food chains in marine ecosystems as well as economically impacting the shellfish industry.

“It’s a photosynthetic organism that plays a big role in carbon cycling, particularly in coastal ecosystems, and can degrade organic carbon,” noted first author Christopher Gobler of Stony Brook University.

“When one of these blooms occurs and you get a billion cells per litre, it represents milligrams of carbon per litre, which is much higher than you typically see in coastal ecosystems.”

The complete genome sequence will let scientists examine its “parts list” for clues to Aureococcus’ ability to capture CO2, survive in varying marine environments, exploit selenium in its proteins, and outgrow many of its competitors.

The 56-million base pair genome of Aureococcus was sequenced by the DOE JGI from a culture isolated sample collected from the shores of Long Island, NY.

“When we looked at the coastal ecosystems where we find Aureococcus blooms, we found they were enriched in organic matter, were very turbid and enriched in trace metals,” Gobler said.

“And when we looked at the genome of Aureococcus, it ended up being enriched in genes to take advantage of these conditions. The surprise was the concordance between the genome and the ecosystem where it’s blooming.”

Gobler said that the work suggests a managerial next step. “We now know this organism is genetically predisposed to exploit certain characteristics of coastal ecosystems. We also know the characteristics are there because of activities of man.

“If we continue to increase, for example, organic matter in coastal waters, then it’s going to continue to favour brown tides since it’s genetically predisposed to thrive in these conditions.”

The study is published online the week of February 21 in the Proceedings of the National Academy of Sciences. (ANI)

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