Strain Y74(T)was an isolate from the sandy soil in the town of Huatugou, Qinghai-Tibet Plateau, China. An analysis of this strain's phenotypic, chemotaxonomic, and genomic characteristics established the relationship of the isolate with the genusPlanococcus. Strain Y74(T)was able to grow between 4 and 42 degrees C (with an optimum temperature of 28 degrees C) at pH values of 6-8.5 and in 0%-7% (w/v) NaCl. The dominant quinones were MK-8 and MK-7. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, and an unknown phospholipid. The majority of the fatty acid content was anteiso-C-15:0(28.8%) followed by C-16:1 omega 7c alcohol (20.9%) and iso-C-14:0(13.4%). The 16S rRNA gene sequence similarity analysis demonstrated a stable branch formed by strain Y74(T)andPlanococcus halotoleransSCU63(T)(99.66%). The digital DNA-DNA hybridization between these two strains was 57.2%. The G + C content in the DNA of Y74(T)was 44.5 mol%. In addition, the morphological, physiological, and chemotaxonomic pattern clearly differentiated the isolates from their known relatives. In conclusion, the strain Y74(T)(=JCM 32826(T) = CICC24461(T)) represents a novel member of the genusPlanococcus,for which the namePlanococcus antioxidanssp. nov. is proposed. Strain Y74(T)was found to have potent antioxidant activity via its hydrogen peroxide tolerance and its 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity. The DPPH radical-scavenging activity was determined to be 40.2 +/- 0.7%. The genomic analysis indicated that six peroxidases genes, one superoxide dismutase gene, and one dprA (DNA-protecting protein) are present in the genome of Y74(T).