Azospirillum zeae sp. nov., a diazotrophic bacterium isolated from rhizosphere soil of Zea mays.
Two free-living nitrogen-fixing bacterial strains, N6 and N7(T), were isolated from corn rhizosphere. A polyphasic taxonomic approach, including morphological characterization, Biolog analysis, DNA-DNA hybridization, and 16S rRNA, cpn60 and nifH gene sequence analysis, was taken to analyse the two strains. 16S rRNA gene sequence analysis indicated that strains N6 and N7(T) both belonged to the genus Azospirillum and were closely related to Azospirillum oryzae (98.7 and 98.8 % similarity, respectively) and Azospirillum lipoferum (97.5 and 97.6 % similarity, respectively). DNA-DNA hybridization of strains N6 and N7(T) showed reassociation values of 48 and 37 %, respectively, with A. oryzae and 43 % with A. lipoferum. Sequences of the nifH and cpn60 genes of both strains showed 99 and approximately 95 % similarity, respectively, with those of A. oryzae. Chemotaxonomic characteristics (Q-10 as quinone system, 18 : 1omega7c as major fatty acid) and G+C content of the DNA (67.6 mol%) were also similar to those of members of the genus Azospirillum. Gene sequences and Biolog and fatty acid analysis showed that strains N6 and N7(T) differed from the closely related species A. lipoferum and A. oryzae. On the basis of these results, it is proposed that these nitrogen-fixing strains represent a novel species. The name Azospirillum zeae sp. nov. is suggested, with N7(T) (=NCCB 100147(T)=LMG 23989(T)) as the type strain.
Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON N5V 4T3, Canada.|School of Biological Sciences, Quaid-e-Azam Campus, University of the Punjab, Lahore 54590, Pakistan.
Samina
S
Mehnaz
Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON N5V 4T3, Canada.
Brian
B
Weselowski
Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON N5V 4T3, Canada.
George
G
Lazarovits
D016949:Azospirillum / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D001482:Base Composition; D018834:Chaperonin 60 / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005227:Fatty Acids / Q000032:analysis; D020459:Genes, rRNA; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation / Q000502:physiology; D009693:Nucleic Acid Hybridization; D010088:Oxidoreductases / Q000235:genetics; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology*; D011809:Quinones / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012988:Soil Microbiology; D003313:Zea mays / Q000382:microbiology*
D001426:Bacterial Proteins; D018834:Chaperonin 60; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D005227:Fatty Acids; D011809:Quinones; D012336:RNA, Ribosomal, 16S; D010088:Oxidoreductases; C029130:nitrogenase reductase