Paenibacillus suaedae sp. nov. and Paenibacillus violae sp. nov., isolated from the roots of Suaeda japonica Makino and Viola mandshurica W. Becker with plant growth-promoting potential.

Abstract

Two novel Gram-positive strains, chi10^T and PFR10^T, were isolated from the roots of Suaeda japonica Makino and Viola mandshurica W. Becker, respectively. The strains are facultatively aerobic, rod-shaped, motile via peritrichous flagella and endospore-forming. Strains chi10^T and PFR10^T showed the highest 16S rRNA gene sequence similarity to Paenibacillus alvei DSM 29^T (99.0%) and Paenibacillus planticolens LMG 31457^T (99.3%). Furthermore, the phylogenetic and phylogenomic analyses demonstrated that strains chi10^T and PFR10^T were closely related to the genus Paenibacillus. The digital DNA-DNA hybridization (dDDH) values for strains used in the phylogenetic analysis and strain chi10^T ranged from 19.6 to 28.4%, while for strain PFR10^T, the values ranged from 19.8 to 53.5%, according to the Genome-to-Genome Distance Calculator 3.0, which were all less than 70%. Additionally, the dDDH value between strains chi10^T and PFR10^T was 22.0%, confirming that they are different species of the genus Paenibacillus. The average nucleotide identity between chi10^T and PFR10^T and other species of the genus Paenibacillus were 68.4-84.7% and 67.8-93.6%, respectively. In addition, the major polar lipids of chi10^T and PFR10^T consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major fatty acid profile of strain chi10^T was iso-C_15 : 0 and anteiso-C_15 : 0, whereas the major fatty acid profile of strain PFR10^T was iso-C_15 : 0, anteiso-C_15 : 0 and iso-C_16 : 0. The sole respiratory quinone in strains chi10^T and PFR10^T was menaquinone-7. Phylogenomic, phenotypic and genome analyses strongly indicated that chi10^T and PFR10^T could be two novel Paenibacillus species for which the names Paenibacillus suaedae sp. nov. (type strain chi10^T = KACC 23258^T = TBRC 17803^T) and Paenibacillus violae sp. nov. (type strain PFR10^T = KACC 23263^T = TBRC 17804^T) are proposed, respectively.