%0 Journal Article %A Vanlaere, Elke %A Baldwin, Adam %A Gevers, Dirk %A Henry, Deborah %A De Brandt, Evie %A LiPuma, John J. %A Mahenthiralingam, Eshwar %A Speert, David P. %A Dowson, Chris %A Vandamme, Peter %T Taxon K, a complex within the Burkholderia cepacia complex, comprises at least two novel species, Burkholderia contaminans sp. nov. and Burkholderia lata sp. nov. %D 2009 %J International Journal of Systematic and Evolutionary Microbiology, %V 59 %N 1 %P 102-111 %@ 1466-5034 %R https://doi.org/10.1099/ijs.0.001123-0 %K MLST, multilocus sequence typing %K RFLP, restriction fragment length polymorphism %K ANI, average nucleotide identity %K ST, sequence type %K Bcc, Burkholderia cepacia complex %I Microbiology Society, %X The aim of the present study was to re-examine the taxonomic position and structure of taxon K (also known as group K) within the Burkholderia cepacia complex (Bcc). For this purpose, a representative set of strains was examined by a traditional polyphasic taxonomic approach, by multilocus sequence typing (MLST) analysis and by analysis of available whole-genome sequences. Analysis of the recA gene sequence revealed three different lineages, designated recA-I, recA-II and recA-III. DNA–DNA hybridization experiments demonstrated that recA-I and recA-II isolates each represented a single novel species. However, DNA–DNA hybridization values of recA-II strains towards recA-III strains and among recA-III strains were at the threshold level for species delineation. By MLST, recA-I isolates were clearly distinguished from the others and represented a distinct lineage referred to as MLST-I, whereas recA-II and recA-III isolates formed a second MLST lineage referred to as MLST-II. A divergence value of 3.5 % was obtained when MLST-I was compared with MLST-II. The internal level of concatenated sequence divergence within MLST-I and MLST-II was 1.4 and 2.7 %, respectively; by comparison with the level of concatenated sequence divergence in established Bcc species, these data demonstrate that the MLST-I and MLST-II lineages represent two distinct species within the Bcc. The latter conclusion was supported by comparison of the whole-genome average nucleotide identity (ANI) level of MLST-I and MLST-II strains with strains of established Bcc species and by a whole-genome-based phylogenetic analysis. We formally propose to classify taxon K bacteria from the MLST-I and MLST-II lineages as Burkholderia contaminans sp. nov. (with strain J2956T =LMG 23361T =CCUG 55526T as the type strain) and Burkholderia lata sp. nov. (with strain 383T =ATCC 17760T =LMG 22485T =CCUG 55525T as the type strain), respectively. The MLST approach was confirmed as a valuable instrument in polyphasic taxonomic studies; more importantly, the cumulative data for about 1000 Bcc isolates analysed demonstrate that the 3 % concatenated sequence divergence level correlates with the 70 % DNA–DNA hybridization or 95 % whole-genome ANI threshold levels for species delineation. %U https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijs.0.001123-0