Reassessment of the taxonomic position of Burkholderia andropogonis and description of Robbsia andropogonis gen. nov., comb. nov.

Abstract

The phylogenetic classification of the species Burkholderia andropogonis within the Burkholderia genus was reassessed using 16S rRNA gene phylogenetic analysis and multilocus sequence analysis (MLSA). Both phylogenetic trees revealed two main groups, named A and B, strongly supported by high bootstrap values (100%). Group A encompassed all of the Burkholderia species complex, whi.le Group B only comprised B. andropogonis species, with low percentage similarities with other species of the genus, from 92 to 95% for 16S rRNA gene sequences and 83% for conserved gene sequences. Average nucleotide identity (ANI), tetranucleotide signature frequency, and percentage of conserved proteins POCP analyses were also carried out, and in the three analyses B. andropogonis showed lower values when compared to the other Burkholderia species complex, near 71% for ANI, from 0.484 to 0.724 for tetranucleotide signature frequency, and around 50% for POCP, reinforcing the distance observed in the phylogenetic analyses. Our findings provide an important insight into the taxonomy of B. andropogonis. It is clear from the results that this bacterial species exhibits genotypic differences and represents a new genus described herein as Robbsia andropogonis gen. nov., comb. nov.

Genome Data Provides High Support for Generic Boundaries in Burkholderia Sensu Lato

“…The two remaining lineages of Burkholderia sensu lato is represented by R. andropogonis [a pathogen of sorghum (Lopes-Santos et al, 2017)] and P. rhizoxinica [a member of Transition Group 1 of Estrada-de los Santos et al (2016)]. Various previous studies have pointed out that these species should be excluded from Burkholderia sensu stricto, Caballeronia and/or Paraburkholderia (e.g., Estrada-de los Santos et al, 2013, 2016; Dobritsa and Samadpour, 2016).…”

“…In fact, they have been suggested to represent new genera (Estrada-de los Santos et al, 2013; Dobritsa and Samadpour, 2016). This debate ultimately culminated in the introduction of the new genus Robbsia to accommodate R. andropogonis (Lopes-Santos et al, 2017). Based on our findings, the taxonomy of P. rhizoxinica requires similar revision.…”

“…Knowledge about these relationships could inform hypotheses regarding the biology and evolution of these bacteria, especially in terms of virulence and pathogenicity. For example, Burkholderia sensu stricto primarily includes human and animal pathogens, while P. rhizoxinica and Robbsia are also represented by pathogens (Estrada-de los Santos et al, 2016; Lopes-Santos et al, 2017). Moreover, certain Caballeronia and Paraburkholderia species have also been isolated from clinical samples [e.g., ‘ C. consitans ’ and ‘ C. turbans ’ (Peeters et al, 2016) and P. fungorum (Coenye et al, 2001), and P. tropica (Deris et al, 2010), respectively].…”

“…Because of this heterogeneity, new genera [e.g., ‘ Caballeronia’ (Gyaneshwar et al, 2011) and ‘ Paraburkholderia’ (Sawana et al, 2014)] has been introduced to accommodate most of the PBE species (Oren and Garrity, 2015a,b, 2017), while retaining the pathogens in Burkholderia sensu stricto. Most recently, a third genus, Robbsia was introduced to accommodate the phytopathogen previously referred to as B. andropogonis (Lopes-Santos et al, 2017). …”

International Committee on Systematics of Prokaryotes Subcommittee for the Taxonomy of Rhizobium and Agrobacterium Minutes of the meeting, Budapest, 25 August 2016

“…andropogonis' within Burkholderia has been reassessed, with the result that it is now described as a member of a new genus, Robbsia andropogonis gen. nov., comb. nov. [22].…”