Pseudomonas leptonychotis sp. nov., isolated from Weddell seals in Antarctica

Abstract

A taxonomic study was carried out on four Gram-stain-negative strains P5773^T, P6169, P4708 and P6245, isolated from anus or mouth samples of Weddell seals at James Ross Island, Antarctica. The results of initial 16S rRNA gene sequence analysis showed that all four strains formed a group placed in the genus <i>Pseudomonas</i> and found <i>Pseudomonas guineae</i> and <i>Pseudomonas peli</i> to be their closest neighbours with 99.9 and 99.2 % sequence similarity, respectively. Sequence analysis of <i>rpoD</i>, <i>rpoB</i> and <i>gyrB</i> housekeeping genes confirmed the highest similarity of isolates to <i>P. peli</i> (<i>rpoD</i>) and to <i>P. guineae</i> (<i>rpoB</i> and <i>gyrB</i>). The average nucleotide identity value below 86 %, as calculated from the whole-genome sequence data, showed the low genomic relatedness of P5773^T to its phylogenetic neighbours. The complete genome of strain P5773^T was 4.4 Mb long and contained genes encoding proteins with biotechnological potential. The major fatty acids of the seal isolates were summed feature 8 (C_{18 : 1} <i>ω</i>7<i>c</i>), summed feature 3 (C_{16 : 1} <i>ω</i> <i>7</i> <i>c</i>/C₁₆ _{: 1} <i>ω</i>6<i>c</i>) and C_16:0. The major respiratory quinone was Q9. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. Putrescine and spermidine are predominant in the polyamine pattern. Further characterization performed using repetitive sequence-based PCR fingerprinting and MALDI-TOF MS analysis showed that the studied isolates formed a coherent cluster separated from the remaining <i>Pseudomonas</i> species and confirmed that they represent a novel species within the genus <i>Pseudomonas</i>, for which the name <i>Pseudomonas</i> <i>leptonychotis</i> sp. nov. is suggested. The type strain is P5773^T (=CCM 8849^T=LMG 30618^T).