DNA Sequencing Gives Insights into Expanding Nutrient Oceanic Dead Zones


Oceanic “Dead Zones” characterized by deficits of oxygen and resulting deficits of many forms of multicellular life are expanding, possibly due to global climate change. To better understand this phenomenon, DOE’s Joint Genome Institute (JGI) has sequenced samples from Saanich Inlet in British Columbia. Metagenomic sequencing (where the composite DNA from an isolated community is sequenced rather than DNA from individual microbes) was carried out. Complete sets of genes coding for a photosynthetic mechanism were found in these composite samples, as expected. However, an extensive set of sulfur-oxidation and nitrogen reducing genes consistent with an anaerobic (no oxygen) life style also was present. The results also suggest that expanding microbial populations in low-oxygen ocean regions similar to the type found here may play a role in CO2 sequestration. They may also prove useful as microbe-based monitoring systems for biological responses to changes in ocean Dead Zones. The research was led by David Walsh and Steven Hallam of the University of British Columbia, working with the JGI’s Susannah Tringe, and is published in the October 23, 2009, issue of Science.


David A. Walsh, Elena Zaikova, Charles G. Howes, Young C. Song, Jody J. Wright, Susannah G. Tringe, Philippe D. Tortell, and Steven J. Hallam, “Metagenome of a Versatile Chemolithoautotroph from Expanding Oceanic Dead Zones” Science Volume 326, pages 578-582 (2009).