Paenibacillus azotifigens sp. nov., a novel nitrogen-fixing bacterium isolated from paddy soil.

A nitrogen-fixing bacterium, designated NF2-4-5, was isolated from a paddy soil in Anseong City, Korea. Cells of strain NF2-4-5 were Gram-staining-positive, motile rods and aerobic. Phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that the strain formed a distinct lineage within the genus Paenibacillus and was closely related to Paenibacillus graminis RSA19 (98.7 %), Paenibacillus jilunlii Be17 (98.6 %), Paenibacillus salinicaeni LAM0A28 (98.6 %) and Paenibacillus riograndensis SBR5 (98.6 %). Growth of strain NF2-4-5 occurs at temperatures of 18-37 °C, at pH 6.0-8.5 and between 0.5% and 2 % NaCl (w/v). The only respiratory quinone was MK-7. The cell wall peptidoglycan of strain NF2-4-5 contained meso-diaminopimelic acid. The main cellular fatty acids were C16 : 0 and anteiso-C15 : 0. The major polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG) and phosphatidylethanolamine (PE). The DNA G+C content was 56.36 mol%. The DNA-DNA hybridization relatedness between strain NF2-4-5 and four reference strains, Paenibacillus graminis RSA19, Paenibacillus jilunlii Be17, Paenibacillus sonchi X19-5 and Paenibacillus riograndensis SBR5, was 22.0±0.3, 20.1±0.7, 18.3±0.3 and 12.6±0.5 %, respectively. The phenotypic, phylogenetic and chemotaxonomic results indicate that the strain NF2-4-5 represents a novel species of the genus Paenibacillus, for which the name Paenibacillus azotifigens sp. nov. is proposed. The type strain is NF2-4-5 (=KACC 18967=LMG 29963).