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Applied and Environmental Microbiology, June 2008, p. 3471-3480, Vol. 74, No. 11
0099-2240/08/$08.00+0     doi:10.1128/AEM.02694-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Characterization of Diazotrophs Containing Mo-Independent Nitrogenases, Isolated from Diverse Natural Environments{triangledown}

Doris A. Betancourt,1* Telisa M. Loveless,2 James W. Brown,1 and Paul E. Bishop1,2

Department of Microbiology,1 USDA Agricultural Research Service, North Carolina State University, Raleigh, North Carolina 27695-76152

Received 29 November 2007/ Accepted 22 March 2008

Molybdenum-independent nitrogenases were first described in the nitrogen-fixing bacterium Azotobacter vinelandii and have since been described in other diazotrophic bacteria. Previously, we reported the isolation of seven diazotrophs with Mo-independent nitrogenases from aquatic environments. In the present study, we extend these results to include diazotrophs isolated from wood chip mulch, soil, "paraffin dirt," and sediments from mangrove swamps. Mo-deficient, N-free media under both aerobic and anaerobic conditions were used for the isolations. A total of 26 isolates were genetically and physiologically characterized. Their phylogenetic placement was determined using 16S rRNA gene sequence analysis. Most of the isolates are members of the gamma subdivision of the class Proteobacteria and appear to be specifically related to fluorescent pseudomonads and azotobacteria. Two other isolates, AN1 and LPF4, are closely related to Enterobacter spp. and Paenibacillus spp., respectively. PCR and/or Southern hybridization were used to detect the presence of nitrogenase genes in the isolates. PCR amplification of vnfG and anfG was used to detect the genetic potential for the expression of the vanadium-containing nitrogenase and the iron-only nitrogenase in the isolates. This study demonstrates that diazotrophs with Mo-independent nitrogenases can be readily isolated from diverse natural environments.

* Corresponding author. Present address: Air Pollution Prevention Control Division, U.S. Environmental Protection Agency, Mail Code E 305-03, Research Triangle Park, NC 27711. Phone: (919) 541-9446. Fax: (919) 541-2157. E-mail: betancourt.doris{at}epa.gov

{triangledown} Published ahead of print on 31 March 2008.

Applied and Environmental Microbiology, June 2008, p. 3471-3480, Vol. 74, No. 11
0099-2240/08/$08.00+0     doi:10.1128/AEM.02694-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Winter, J. M., Moore, B. S. (2009). Exploring the Chemistry and Biology of Vanadium-dependent Haloperoxidases. J. Biol. Chem. 284: 18577-18581 [Abstract] [Full Text]  


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