Paenibacillus beijingensis sp. nov., a nitrogen-fixing species isolated from wheat rhizosphere soil.

A novel nitrogen-fixing bacterium, BJ-18(T), was isolated from wheat rhizosphere soil. Strain BJ-18(T) was observed to be Gram-positive, facultatively anaerobic, motile and rod-shaped (0.4-0.9 μm × 2.0-2.9 μm). Phylogenetic analysis based on a partial nifH gene sequence and an assay for nitrogenase activity showed its nitrogen-fixing capacity. Phylogenetic analysis based on full 16S rRNA gene sequences suggested that strain BJ-18(T) is a member of the genus Paenibacillus. High similarity of 16S rRNA gene sequence was found between BJ-18(T) and Paenibacillus peoriae DSM 8320(T) (99.05 %), Paenibacillus jamilae DSM 13815(T) (98.86 %), Paenibacillus brasiliensis DSM 13188(T) (98.55 %), Paenibacillus polymyxa DSM 36(T) (98.74 %), Paenibacillus terrae DSM 15891(T) (97.99 %) and Paenibacillus kribbensis JCM 11465(T) (97.92 %), whereas the similarity was below 96.0 % between BJ-18(T) and the other Paenibacillus species. DNA-DNA relatedness between strain BJ-18(T) and P. peoriae DSM 8320(T), P. jamilae DSM 13815(T), P. brasiliensis DSM 13188(T), P. polymyxa DSM 36(T), P. kribbensis JCM 11465(T) and P. terrae DSM 15891(T) was determined to be 43.6 ± 2.7, 34.2 ± 5.3, 47.9 ± 6.6, 36.8 ± 3.5, 27.4 ± 4.3 and 23.6 ± 4.1 % respectively. The DNA G+C content of BJ-18(T) was determined to be 45.8 mol %. The major fatty acid was identified as anteiso-C15:0 (67.1 %). The polar lipids present in strain BJ-18(T) were identified as diphosphatidylglycerol, phosphatidyl methylethanolamine, phosphatidylethanolamine and phosphatidylglycerol. The phenotypic and genotypic characteristics, and DNA-DNA relatedness data, suggest that BJ-18(T) represents a novel species of the genus Paenibacillus, for which the name Paenibacillus beijingensis sp. nov. (Type strain BJ-18(T)=DSM25425(T)=CGMCC 1.12045(T)) is proposed.