James W. Brown

Associate Professor & Undergraduate Coordinator
Department of Microbiology, NC State University

NC ASM 2006 Branch Meeting, October 12, 2006, Raleigh, NC

Phylogenetic analysis of Azomonas insignis.

Lee-Brown, M.J., J. Evans, J.W. Brown. Guilford College and NC State University.

The azotobacteria are free-living nitrogen fixers specifically related to the fluorescent pseudomonads. A preliminary analysis of the little-characterized species Azomonas insignis (ATCC 12523) suggested that this organism was not a member of this phylogenetic group. We report here the phylogenetic analysis of A. insignis, using both small subunit (16S) ribosomal RNA and ribonuclease P RNA sequences. These independent markers both show that this organism is actually a member of the genus Acinetobacter, a member of the Moraxella group, and only distantly related to the fluorescent pseudomonads and azotobacteria. Characterized species of Acinetobacter (Acinetobacter baumannii is an emerging opportunistic pathogen) are not known to be able to fix nitrogen, but growth on nitrogen-free medium was confirmed with the named species “Azomonas insignis” which is capable of utilizing dinitrogen as the sole nitrogen source.
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