Azospirillum halopraeferens sp. nov., a Nitrogen-Fixing Organism Associated with Roots of Kallar Grass (Leptochloa fusca (L.) Kunth)

Abstract

Among the nitrogen-fixing bacteria associated with the roots of Leptochloa fusca (L.) Kunth in salt-affected soils in the Punjab region of Pakistan, we found a homogeneous group of eight diazotrophs. Cells are vibrioid to S shaped, are motile by one polar flagellum, and produce granules of poly-P-hydroxybutyrate. They have a respiratory type of metabolism, show microaerophilic growth when fixing nitrogen, grow well on salts of organic acids, and can also use fructose and mannitol. On nitrogen-free semisolid media, they require biotin, utilize mannitol, but not glucose or sucrose, and cannot acidify glucose aerobically or anaerobically. Optimal growth occurs at 0.25 % NaCl and 41OC. Deoxyribonucleic acid (DNA)-ribosomal ribonucleic acid (rRNA) hybridizations show that the organisms belong to the Azospirilhm rRNA branch, where they cluster together with Azospirilhm amazonense. They form a phenotypically and protein electrophoretically homogeneous group of bacteria, clearly distinct from Azospirillum amazonense, Azospirillum lipoferum, and Azospirillum brasilense. As no DNA-DNA binding was found with any of the three Azospirillum species, we propose a fourth Azospirilhm species for this group of isolates. Because of better growth at increased NaCl concentrations, we named the new species Azospirillum halopraeferens, Strain Au 4 (= LMG 7108) is the type strain, which has been deposited at the Deutsche Sammlung von Mikroorganismen, Gottingen, Federal Republic of Germany, as DSM 3675.

Biological Nitrogen Fixation

“…Dentro de las relaciones favorables se encuentra la asociación con bacterias fijadoras de nitrógeno; entre estas, especies de Azospirillum 1 , Enterobacter, Klebsiella, Pseudomonas y Burkholderia (Estrada et al, 2001 (Tarrand et al,1978;Magelhaes et al, 1983;Reinhold et al, 1987;Khammas et al, 1989;Sly y Stackebrandt, 1999;Eckert et al, 2001); desde entonces ha sido aislada de varias especies cultivadas y silvestres y de varios tipos de suelo.…”

History on the biological nitrogen fixation research in graminaceous plants: special emphasis on the Brazilian experience

“…Other Azospirillum species -During the last two decades, other species of Azospirillum have been described: A. halopraeferens associated with Kallar grass grown in saline soils of Pakistan (Reinhold et al 1987), A. irakense associated with rice plants grown in Iraq (Khammas et al 1989), A. largimobile (the original name largomobile was orthographically incorrect) isolated from a water sample collected from a lake in Australia (Dekhil et al 1997) and A. doebereinerae associated with Pennisetun plants grown in Germany ). Very few studies have been carried out with these Azospirillum species, except for A. irakense where pectinolytic activity was observed (Vande Broek and Vanderleyden 1995).…”

Fodinicurvata sediminis gen. nov., sp. nov. and Fodinicurvata fenggangensis sp. nov., poly- -hydroxybutyrate-producing bacteria in the family Rhodospirillaceae

“…However, moderate amounts of C 18 : 1 2-OH (12.2-14.7 %) and C 19 : 0 cyclo v8c (7.9-7.4 %) were found in strains YIM D82 T and YIM D812 T , but were not found at significant levels in the genus Rhodovibrio. In addition, the presence of fatty acids iso-C 15 : 0 G, C 18 : 1 v9c and C 20 : 2 v6,9c clearly differentiated the two novel isolates from the genera Rhodovibrio, Azospirillum, Tistrella, Inquilinus and Nissen & Dundas, 1984;Mack et al, 1993;Imhoff et al, 1998;Garrity et al, 2005); 4, Azospirillum (Tarrand et al, 1978;Reinhold et al, 1987;Khammas et al, 1989;Sly & Stackebrandt, 1999;Eckert et al, 2001;Xie & Yokota, 2005;Peng et al, 2006;Mehnaz et al, 2007a, b;Young et al, 2008); 5, Rhodocista (Favinger et al, 1989;Kawasaki et al, 1992;Imhoff et al, 1998;Zhang et al, 2003); 6, Defluviicoccus (Maszenan et al, 2005); 7, Tistrella (Shi et al, 2002); 8, Skermanella (Sly & Stackebrandt, 1999); 9, Inquilinus (Coenye et al, 2002); 10, Thalassobaculum (Zhang et al, 2008). +, Positive; W, weakly positive; 2, negative; V, variable; NA, not available.…”