Expanding the Complex with the Addition of Two Novel Species: sp. nov. and sp. nov.

Distinct strains were isolated from soil samples collected in tropical northern Australia (Northern Territory and the Torres Strait Islands, Queensland). Phylogenetic analysis of 16S rRNA and whole genome sequences revealed these strains were distinct from previously described species and assigned them to two novel clades within the B. pseudomallei complex (Bpc). Because average nucleotide identity and digital DNA-DNA hybridization calculations are consistent with these clades representing distinct species, we propose the names Burkholderia mayonis sp. nov. and Burkholderia savannae sp. nov. Strains assigned to sp. nov. include type strain BDU6 (=TSD-80; LMG 29941; ASM152374v2) and BDU8. Strains assigned to sp. nov. include type strain MSMB266 (=TSD-82; LMG 29940; ASM152444v2), MSMB852, BDU18, and BDU19. Comparative genomics revealed unique coding regions for both putative species, including clusters of orthologous genes associated with phage. Type strains of both sp. nov. and sp. nov. yielded biochemical profiles distinct from each other and from other species in the Bpc, and profiles also varied among strains within sp. nov. and sp. nov. Matrix-assisted laser desorption ionization time-of-flight (MLST) analysis revealed a sp. nov. cluster separate from other species, whereas sp. nov. strains did not form a distinct cluster. Neither sp. nov. nor sp. nov. caused mortality in mice when delivered via the subcutaneous route. The addition of sp. nov. and sp. nov. results in a total of eight species currently within the Bpc. species can be important sources of novel natural products, and new species are of interest to diverse scientific disciplines. Although many species are saprophytic, Burkholderia pseudomallei is the causative agent of the disease melioidosis. Understanding the genomics and virulence of the closest relatives to B. pseudomallei, i.e., the other species within the B. pseudomallei complex (Bpc), is important for identifying robust diagnostic targets specific to B. pseudomallei and for understanding the evolution of virulence in B. pseudomallei. Two proposed novel species, sp. nov. and sp. nov., were isolated from soil samples collected from multiple locations in northern Australia. The two proposed species belong to the Bpc but are phylogenetically distinct from all other members of this complex. The addition of sp. nov. and sp. nov. results in a total of eight species within this significant complex of bacteria that are available for future studies.