Paenibacillus rhizophilus sp. nov., a nitrogen-fixing bacterium isolated from the rhizosphere of wheat (Triticum aestivum L.)

Abstract

A novel Gram-stain-variable, endospore-forming, motile, rod-shaped, facultative aerobic bacterium, designated 7197^T, was isolated from rhizosphere soil of wheat (<i>Triticum aestivum</i> L.) collected from Yakeshi County, Inner Mongolia, PR China. This isolate was found to have the highest 16S rRNA gene sequence similarity to <i>Paenibacillussabinae</i> T27^T (98.0 %), followed by <i>Paenibacillussophorae</i> S27^T (97.9 %) and <i>Paenibacillusforsythiae</i> T98^T (97.7 %). To ascertain the genomic relatedness of this strain to its phylogenetic neighbours, its genome sequence was determined. The average nucleotide identity values of genome sequences between the novel isolate and the type strains of related species <i>P. sabinae</i> T27^T, <i>P. sophorae</i> S27^T and <i>P. forsythiae</i> T98^T were 87.9 %, 85.8 and 83.9 %, respectively. The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, four unidentified aminophospholipids and one unidentified aminolipid. The major cellular fatty acids were anteiso-C_{15 : 0} (56.3 %), C_{16 : 0} (15.7 %) and iso-C_{15 : 0} (14.1 %).The genome size of strain 7197^T was 5.21 Mb, comprising 4879 predicted genes with a DNA G+C content of 51.9 mol%. Menaquinone-7 was reported as the major respiratory quinone. The diamino acid in the cell-wall peptidoglycan was found to be <i>meso</i>-diaminopimelic acid. Based on phylogenetic, genomic, chemotaxonomic and phenotypic characteristics, strain 7197^T was classified as a novel species within the genus <i>Paenibacillus</i>, for which the name <i>Paenibacillus rhizophilus</i> sp. nov. is proposed. The type strain of <i>Paenibacillus rhizophilus</i> is 7197^T (=DSM 103168^T=CGMCC 1.15699^T).