Rhodococcus navarretei sp. nov. and Pseudarthrobacter quantipunctorum sp. nov., two novel species with the ability to biosynthesize fluorescent nanoparticles, isolated from soil samples at Union Glacier, Antarctica

Two Gram-stain-positive bacterial strains, EXRC-4A-4^T and RC-2-3^T, were isolated from soil samples collected at Union Glacier, Antarctica. Based on 16S rRNA gene sequence similarity, strain EXRC-4A-4^T was identified as belonging to the genus <i>Rhodococcus</i>, and strain RC-2-3^T to the genus <i>Pseudarthrobacter</i>. Further genomic analyses, including average nucleotide identity and digital DNA-DNA hybridization, suggested that these strains represent new species. Strain EXRC-4A-4^T exhibited growth at temperatures ranging from 4 to 28 °C (optimum between 20 and 28 °C), at pH 5.0-9.0 (optimum, pH 6.0), and in the presence of 0-5.0% NaCl (optimum between 0 and 1% NaCl). Strain RC-2-3^T grew at 4-28 °C (optimum growth at 28 °C), pH 6.0-10 (optimum, pH 7.0) and in the presence of 0-5.0% NaCl (optimum, 1% NaCl). The fatty acid profile of EXRC-4A-4^T was dominated by C_{17:1 ω-7}, while that of RC-2-3^T was dominated by anteiso-C_{15 : 0}. The draft genome sequences revealed a DNA G+C content of 64.6 mol% for EXRC-4A-4^T and 65.8 mol% for RC-2-3^T. Based on this polyphasic study, EXRC-4A-4^T and RC-2-3^T represent two novel species within the genera <i>Rhodococcus</i> and <i>Pseudarthrobacter</i>, respectively. We propose the names <i>Rhodococcus navarretei</i> sp. nov. and <i>Pseudarthrobacter quantipunctorum</i> sp. nov. The type strains are <i>Rhodococcus navarretei</i> EXRC-4A-4^T and <i>Pseudarthrobacter quantipunctorum</i> RC-2-3^T. These strains have been deposited deposited in the CChRGM and BCCM/LMG culture collections with entry numbers RGM 3539/LMG 33621 and RGM 3538/LMG 33620, respectively.