Present address: University of California, Ocean Sciences Department, Earth and Marine Sciences Building Room A-433, Santa Cruz, CA 95064, USA.
The presence of the glycolysis operon in SAR11 genomes is positively correlated with ocean productivity
Article first published online: 3 NOV 2009
© 2009 Society for Applied Microbiology and Blackwell Publishing Ltd
Volume 12, Issue 2, pages 490–500, February 2010
How to Cite
Schwalbach, M. S., Tripp, H. J., Steindler, L., Smith, D. P. and Giovannoni, S. J. (2010), The presence of the glycolysis operon in SAR11 genomes is positively correlated with ocean productivity. Environmental Microbiology, 12: 490–500. doi: 10.1111/j.1462-2920.2009.02092.x
- Issue published online: 26 JAN 2010
- Article first published online: 3 NOV 2009
- Received 14 November, 2008; accepted 10 September, 2009.
Bacteria in the SAR11 clade are highly abundant in marine surface waters, but currently little is known about the carbon compounds that support these large heterotrophic populations. To better understand the carbon requirements of these organisms, we conducted a multiphasic exploration of carbohydrate utilization among SAR11 isolates from the Northeast Pacific Ocean and the Sargasso Sea. A comparison of three SAR11 genomes showed they all lacked a recognizable PTS system, the oxidative portion of the pentose phosphate shunt (zwf-, pgl-), genes for the Embden–Meyerhoff–Parnas (pfk-, pyk-) and Entner–Doudoroff (eda-) pathways of glycolysis. Strain HTCC7211, isolated from an ocean gyre, was missing other glycolysis genes as well. Growth assays, radioisotopes, metagenomics and microarrays were used to test the hypothesis that these isolates might be limited in their abilities to transport and oxidize exogenous carbohydrates. Galactose, fucose, rhamnose, arabinose, ribose and mannose could not serve as carbon sources for the isolates tested. However, differences in glucose utilization were detected between coastal and ocean gyre isolates, with the coastal isolates capable of transporting, incorporating and oxidizing glucose while the open ocean isolate could not. Subsequent microarray analysis of a coastal isolate suggested that an operon encoding a variant of the Entner–Doudoroff pathway is likely responsible for the observed differences in glucose utilization. Metagenomic analysis indicated this operon is more commonly found in coastal environments and is positively correlated with chlorophyll a concentrations. Our results indicated that glycolysis is a variable metabolic property of SAR11 metabolism and suggest that glycolytic SAR11 are more common in productive marine environments.