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, chi10T and PFR10T, 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 endosporeforming. Strains chi10T and PFR10T showed the highest 16S rRNA gene sequence similarity to Paenibacillus alvei DSM 29T (99.0%) and Paenibacillus planticolens LMG 31457T (99.3%). Furthermore, the phylogenetic and phylogenomic analyses demonstrated that strains chi10T and PFR10T were closely related to the genus Paenibacillus. The digital DNA-DNA hybridization (dDDH) values for strains used in the phylogenetic analysis and strain chi10T ranged from 19.6 to 28.4%, while for strain PFR10T, 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 chi10T and PFR10T was 22.0%, confirming that they are different species of the genus Paenibacillus. The average nucleotide identity between chi10T and PFR10T 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 chi10T and PFR10T consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major fatty acid profile of strain chi10T was iso-C15: 0 and anteiso- C15:0, whereas the major fatty acid profile of strain PFR10T was iso- C15:0, anteiso-C15: 0 and iso- C16:0. The sole respiratory quinone in strains chi10T and PFR10T was menaquinone- 7. Phylogenomic, phenotypic and genome analyses strongly indicated that chi10T and PFR10T could be two novel Paenibacillus species for which the names Paenibacillus suaedae sp. nov. (type strain chi10T = KACC 23258T = TBRC 17803T) and Paenibacillus violae sp. nov. (type strain PFR10T = KACC 23263T = TBRC 17804T) are proposed, respectively.