Pseudomonas tussilaginis sp. nov., isolated from leaves of coltsfoot growing in mercury-contaminated soil

Three mercury-resistant isolates of a novel <i>Pseudomonas</i> species were obtained from the leaves of coltsfoot (<i>Tussilago farfara</i> L.) growing in mercury-contaminated soil in Southern Poland. Using the 16S rRNA gene sequence, they were identified as likely <i>Pseudomonas arcuscaelestis</i> isolates. Whole-genome analyses based on phylogenomic analyses and overall genome relatedness indices showed that they are three nearly identical isolates of a novel species, with <i>Pseudomonas alkylphenolica</i> KL28^T as the closest type species by overall genome relatedness indices [86.64% average nucleotide identity (ANI), 34.2% digital DNA-DNA hybridization (dDDH)] and with <i>P. arcuscaelestis</i> P66^T (83.85% ANI, 28.5% dDDH) and <i>Pseudomonas auratipiscis</i> 119P^T (83.66% average nucleotide identity, 28.4% dDDH) as the two closest by maximum likelihood phylogenomic analysis. Moreover, five genomes publicly available in the databases were found. One of the three isolates, Hg5Tf, was further characterized as Gram-negative, motile, facultatively aerobic rods, which can be distinguished from closely related species by the (delayed) positive urease reaction in the API20NE test and by weak growth on pectin, d-lactic acid methyl ester and acetoacetic acid in the BIOLOG Gen III test. Matrix-assisted laser-desorption/ionization time-of-flight profile of Hg5Tf^T is also distinct from those of closely related species. A novel species of genus <i>Pseudomonas</i> is proposed with the name <i>Pseudomonas tussilaginis</i> sp. nov. and Hg5Tf^T (=CCM 9461^T=PCM 3563^T) as its type strain.