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

Publisher Website
Google Scholar
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-β-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 41°C. Deoxyribonucleic acid (DNA)-ribosomal ribonucleic acid (rRNA) hybridizations show that the organisms belong to the Azospirillum rRNA branch, where they cluster together with Azospirillum 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 Azospirillum 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, Göttingen, Federal Republic of Germany, as DSM 3675.

This publication has 12 references indexed in Scilit: