Paenibacillus macquariensis subsp. defensor subsp. nov., isolated from boreal soil

Two Gram-variable, aerobic, motile, rod-shaped, endospore-forming bacterial strains, M4-2T and M4-1, were isolated from soil samples collected from Oblast Magadan, Russian Far East, as micro-organisms antagonistic to the psychrophilic phytopathogenic fungus Typhula ishikariensis. Strains M4-2T and M4-1 were identified as members of the genus Paenibacillus by phenotypic and phylogenetic analyses based on 16S rRNA gene sequences. The strains contained anteiso-C15:0 as the major fatty acid (63.0-64.7%) and MK-7 as the major isoprenoid quinone. The DNA G+C contents were 42.8 and 41.7 mol%, respectively. 16S rRNA gene sequence analysis showed that strains M4-2T and M4-1 exhibited high similarities with Paenibacillus macquariensis DSM 2T (99.5 and 99.7%, respectively) and Paenibacillus antarcticus LMG 22078T (99.4 and 99.5%, respectively). There were no clear differences in the phenotypic characteristics and chemotaxonomic and phylogenetic data between the novel isolates and P. macquariensis DSM 2T. DNA-DNA hybridization experiments between strain M4-2T and P. macquariensis DSM 2T and P. antarcticus LMG 22078T revealed reassociation values of 56 and 49%, respectively. Multilocus sequence analysis confirmed the differences between the new isolates and reference strains that were observed with the DNA-DNA hybridization studies. On the basis of the results described above, it is proposed that the isolates represent a novel subspecies of P. macquariensis, Paenibacillus macquariensis subsp. defensor subsp. nov. The type strain is M4-2T (=JCM 14954T=NCIMB 14397T).