Acinetobactercelticus sp. nov., a psychrotolerant species widespread in natural soil and water ecosystems.

A novel, taxonomically unique group of six strains of the genus Acinetobacter was discovered during an exploratory study on strains culturable from soil and water natural ecosystems in the Bohemian part of the Czech Republic. Based on the comparative analyses of the 16S rRNA gene, gyrB and rpoB sequences, these strains formed strongly supported and internally coherent clusters (intracluster identities of ≥99.9, ≥96.1 and ≥97.3 %, respectively), which were clearly separated from all known species of the genus Acinetobacter (≤98.7, ≤83.2 and ≤88.9 %, respectively). The distinctness of the group at the species level was evidenced also by the results of the genus-wide analyses of the whole-cell mass fingerprints of the six strains generated by matrix-assisted laser desorption/ionization-time-of-flight MS and the whole-genome sequence of a group member, ANC 4603T. Compared with the known species of the genus Acinetobacter, all six strains exhibited a unique phenotype, characterized by psychrotolerance (growth at 1 °C through 28 °C), the inability to grow at 32 °C and the ability to assimilate l-aspartate and malonate but not 2,3-butanediol or citrate. Based on these results, the name Acinetobacter celticus sp. nov. is proposed for the taxon represented by the six strains. The type strain is ANC 4603T (=CCM 8700T=CCUG 69239T=CNCTC 7549T).