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Aquatic Microbial Ecology

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AME 59:283-293 (2010)  -  DOI:

High diversity of Rhodobacterales in the subarctic North Atlantic Ocean and gene transfer agent protein expression in isolated strains

Yunyun Fu1,*, Dawne M. MacLeod1,*, Richard B. Rivkin2, Feng Chen3, Alison Buchan4, Andrew S. Lang1,**

1Department of Biology, Memorial University of Newfoundland, 232 Elizabeth Ave., St. John’s, Newfoundland A1B 3X9, Canada
2Ocean Sciences Centre, Memorial University of Newfoundland, Marine Lab Road, St. John’s, Newfoundland A1C 5S7, Canada
3Center of Marine Biotechnology, University of Maryland Biotechnology Institute, 236-701 East Pratt St., Baltimore, Maryland 21202, USA
4Department of Microbiology, University of Tennessee, M409 Walters Life Sciences, Knoxville, Tennessee 37914, USA
*These authors contributed equally
**Corresponding author. Email:

ABSTRACT: Genes encoding gene transfer agent (GTA) particles are well conserved in bacteria of the order Rhodobacterales. Members of this order are abundant in diverse marine environments, frequently accounting for as much as 25% of the total bacterial community. Conservation of the genes encoding GTAs allows their use as diagnostic markers of Rhodobacterales in biogeographical studies. The first survey of the diversity of Rhodobacterales based on the GTA major capsid gene was conducted in a warm temperate estuarine ecosystem, the Chesapeake Bay, but the biogeography of Rhodobacterales has not been explored extensively. This study investigates Rhodobacterales diversity in the cold subarctic water near Newfoundland, Canada. Our results suggest that the subarctic region of the North Atlantic contains diverse Rhodobacterales communities in both winter and summer, and that the diversity of the Rhodobacterales community in the summer Newfoundland coastal water is higher than that found in the Chesapeake Bay, in either the summer or winter. Approximately one-third of GTA sequences retrieved from the subarctic waters were most closely related to those from bacteria isolated from sea ice or cold regions. Distinguishable diversity patterns were found between the temperate and subarctic waters, providing further support for niche adaptation of specific Rhodobacterales members to unique environments. We also demonstrate that a number of Rhodobacterales strains, from both the subarctic and temperate locations, express the GTA major capsid protein. This provides robust evidence that the widespread conservation of GTA genes in the Rhodobacterales may result in the production of functionally similar and active GTA systems in these bacteria in different environments.

KEY WORDS: Rhodobacterales · Gene transfer agent · GTA · Major capsid protein

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Cite this article as: Fu Y, MacLeod DM, Rivkin RB, Chen F, Buchan A, Lang AS (2010) High diversity of Rhodobacterales in the subarctic North Atlantic Ocean and gene transfer agent protein expression in isolated strains. Aquat Microb Ecol 59:283-293.

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