Abstract

Two Gram-stain-positive bacterial strains, EXRC-4A-4T T and RC-2-3T, T , were isolated from soil samples collected at Union Glacier, Antarctica. Based on 16S rRNA gene sequence similarity, strain EXRC- 4A- 4T T was identified as belonging to the genus Rhodococcus, , and strain RC- 2- 3T T to the genus Pseudarthrobacter. . Further genomic analyses, including average nucleotide identity and digital DNA-DNA hybridization, suggested that these strains represent new species. Strain EXRC- 4A- 4T T exhibited growth at temperatures ranging from 4 to 28 degrees C (optimum between 20 and 28 degrees 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- 3T T grew at 4-28 degrees C (optimum growth at 28 degrees 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- 4T T was dominated by C 17:1 omega-7, , while that of RC- 2- 3T 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-4T T and 65.8 mol% for RC- 2- 3T. T . Based on this polyphasic study, EXRC- 4A- 4T T and RC-2-3T T represent two novel species within the genera Rhodococcus and Pseudarthrobacter, , respectively. We propose the names Rhodococcus navarretei sp. nov. and Pseudarthrobacter quantipunctorum sp. nov. The type strains are Rhodococcus navarretei EXRC-4A-4T T and Pseudarthrobacter quantipunctorum RC-2-3T. 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.