Nitrogen-Fixing Paenibacillus haidiansis and Paenibacillus sanfengchensis: Two Novel Species from Plant Rhizospheres

Two strains, M1 and H32 with nitrogen-fixing ability, were isolated from the rhizospheres of different plants. Genome sequence analysis showed that a <i>nif</i> (<i>ni</i>trogen <i>f</i>ixation) gene cluster composed of nine genes (<i>nifB nifH nifD nifK nifE nifN nifX hesA nifV</i>) was conserved in the two strains. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strains M1 and H32 are members of the genus <i>Paenibacillus</i>. Strains M1 and H32 had 97% similarity in the 16S rRNA gene sequences. Strain M1 had the highest similarity (97.25%) with <i>Paenibacillus vini</i> LAM 0504T in the 16S rRNA gene sequences. Strain H32 had the highest similarity (97.48%) with <i>Paenibacillus faecis</i> TCIP 101062T in the 16S rRNA gene sequences. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain M1 and its closest member <i>P. vini</i> were 78.17% and 22.3%, respectively. ANI and dDDH values between strain H32 and its closest member <i>P. faecis</i> were 88.94% and 66.02%, respectively. The predominant fatty acid of both strains is anteiso-C15:0. The major polar lipids of both strains are DPG (diphosphatidylglycerol) and PG (phosphatidylglycerol). The predominant isoprenoid quinone of both strains is MK-7. With all the phylogenetic and phenotypic divergency, two novel species <i>Paenibacillus haidiansis</i> sp. nov and <i>Paenibacillus sanfengchensis</i> sp. nov are proposed with the type strain M1^T [=GDMCC (Guangdong Culture Collection Centre of Microbiology) 1.4871 = JCM (Japan Collection of Microorganisms) 37487] and with type strain H32^T (=GDMCC 1.4872 = JCM37488).