- International Journal of Systematic and Evolutionary Microbiology
- Volume 43, Issue 3
f Azoarcus gen. nov., Nitrogen-Fixing Proteobacteria Associated with Roots of Kallar Grass (Leptochloa fusca (L.) Kunth), and Description of Two Species, Azoarcus indigens sp. nov. and Azoarcus communis sp. nov.
- Authors: Barbara Reinhold-Hurek†,*, Thomas Hurek‡, Monique Gillis, Bart Hoste, Marc Vancanneyt, Karel Kersters, Jozef De Ley
- *Corresponding author.
- First Published Online: 01 July 1993, International Journal of Systematic and Evolutionary Microbiology 43: 574-584, doi: 10.1099/00207713-43-3-574
- Subject: Original Papers Relating To Systematic Bacteriology
- Issue Published:
Azoarcus gen. nov., Nitrogen-Fixing Proteobacteria Associated with Roots of Kallar Grass (Leptochloa fusca (L.) Kunth), and Description of Two Species, Azoarcus indigens sp. nov. and Azoarcus communis sp. nov., Page 1 of 1< Previous page | Next page > /docserver/preview/fulltext/ijsem/43/3/ijs-43-3-574-1.gif
Among the nitrogen-fixing bacteria associated with roots of Leptochloa fusca (L.) Kunth in saline-sodic soils in the Punjab of Pakistan, we repeatedly found yellow-pigmented, straight to curved, gram-negative rods. To group and identify these organisms, we examined morphological, nutritional, and biochemical features and performed polyacrylamide gel electrophoretic analyses of cellular proteins, gas chromatographic analyses of fatty acids, DNA-rRNA hybridizations, and DNA-DNA hybridizations. Our results showed that 11 isolates formed five groups distinct at the species level, with each group containing one to three members. These bacteria constituted a separate rRNA branch in rRNA superfamily III (corresponding to the beta subclass of the Proteobacteria) at a branching Tm(e) level of 67.7°C [Tm(e) is the temperature at which 50% of a hybrid is denatured under standard conditions]. On this branch, the five groups were located in two clusters with Tm(e) values of 79.4 to 80.4°C and around 71.5°C. We propose a new genus, the genus Azoarcus, for these strains. Azoarcus indigens is the type species and has a growth factor requirement; its type strain is strain VB32 (= LMG 9092). A second named species, Azoarcus communis, includes a strain obtained from French refinery oily sludge, strain LMG 5514. Bacteria of this genus have a strictly aerobic type of metabolism, fix nitrogen microaerobically, and grow well on salts of organic acids but not on carbohydrates. Swedish isolates obtained from human sources (E. Falsen group 15 strains LMG 6115 and LMG 6116), as well as “[Pseudomonas] gasotropha” LMG 7583T, were also located on this rRNA branch at a lower Tm(e) level (70.4 to 71.2°C).
Present address: Pfarracker 5, DW-35043 Marburg-Bauerbach, Germany.
Present address: Max-Planck-Institut für Terrestrische Mikrobiologie, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany.
Copyright © 1993 International Union of Microbiological Societies | Published by the Microbiology Society
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