Subtercola endophyticus sp. nov., a cold-adapted bacterium isolated from Abies koreana

A novel Gram-stain-positive, aerobic bacterial strain, designated AK-R2A1-2 T , was isolated from surface-sterilized needle leaves of an Abies koreana tree. Strain AK-R2A1-2 T was closely related to Subtercola boreus K300 T and Subtercola lobariae 9583b T with 97.3% and 96.7% 16S rRNA gene sequence similarities, respectively, and it formed a distinct phyletic lineage from these two strains. Growth of strain AK-R2A1-2 T was observed at 4–25°C with pH 5.0–8.0. Strain AK-R2A1-2 T contained menaquinone 9 (MK-9) and menaquinone 10 (MK-10) as the predominant respiratory quinones. The major cellular fatty acids were anteiso-C 15:0 and summed feature 8 (C 18:1 ω7 c or/and C 18:1 ω6 c ), and the polar lipids comprised diphosphatidylglycerol (DPG), and three unknown aminolipids (AKL2, AKL3, and AKL4). The complete genome of strain AK-R2A1-2 T was sequenced to understand the genetic basis of the survival strategy of the strain in low temperatures. Multiple copies of cold-associated genes involved in cold-active chaperon, stress response, and DNA repair supported survivability of the strain at low temperatures. Finally, this strain could significantly improve rice seeding growth under low temperatures. Strain AK-R2A1-2 T is concluded to represent a novel species of the genus Subtercola , and the proposed name is Subtercola endophyticus sp. nov. The type strain is AK-R2A1-2 T (= KCTC 49721 T = GDMCC 1.2921 T ).