A novel, nostoxanthin-producing, endophytic bacterium, designated as AK-PDB1-5T, was isolated from the needle-like leaves of the Korean fir (Abies koreana Wilson) collected from Mt. Halla in Jeju, South Korea. A 16S rRNA sequence comparison indicated that the closest phylogenetic neighbors were Sphingomonas crusticola MIMD3T (95.6%) and Sphingomonas jatrophae S5-249T (95.3%) of the family Sphingomonadaceae. Strain AK-PDB1-5T had a genome size of 4,298,284 bp with a 67.8% G + C content, and digital DNA–DNA hybridization and OrthoANI values with the most closely related species of only 19.5–21% and 75.1–76.8%, respectively. Cells of the strain AK-PDB1-5T were Gram-negative, short rods, oxidase- and catalase-positive. Growth occurred at pH 5.0–9.0 (optimum pH 8.0) in the absence of NaCl at 4–37°C (optimum 25–30°C). Strain AK-PDB1-5T contained C14:0 2OH, C16:0 and summed feature 8 as the major cellular fatty acids (> 10%), while sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, phospholipids and lipids were found to be the major polar lipids. The strain produces a yellow carotenoid pigment; natural products prediction via AntiSMASH tool found zeaxanthin biosynthesis clusters in the entire genome. Biophysical characterization by ultraviolet–visible absorption spectroscopy and ESI-MS studies confirmed the yellow pigment was nostoxanthin. In addition, strain AK-PDB1-5T was found significantly promote Arabidopsis seedling growth under salt conditions by reducing reactive oxygen species (ROS). Based on the polyphasic taxonomic analysis results, strain AK-PDB1-5T was determined to be a novel species in the genus Sphingomonas with the proposed name Sphingomonas nostoxanthinifaciens sp. nov. The type strain is AK-PDB1-5T (= KCTC 82822T = CCTCC AB 2021150T).

A novel Gram-stain-positive, aerobic bacterial strain, designated AK-R2A1-2 T, was isolated from the surface-sterilized needle leaves of an Abies koreana tree. Strain AK-R2A1-2 T had 97.3% and 96.7% 16S rRNA gene sequence similarities with Subtercola boreus K300T and Subtercola lobariae 9583bT, respectively, but formed a distinct phyletic lineage from these two strains. Growth of strain AK-R2A1-2 T was observed at 4–25 °C at 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-C15:0 and summed feature 8 (C18:1ω7c or/and C18:1ω6c), and the polar lipids included 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 its survival at low temperatures. Multiple copies of cold-associated genes involved in cold-active chaperon, stress response, and DNA repair supported survival of the strain at low temperatures. Strain AK-R2A1-2 T was also able to significantly improve rice seedling growth under low temperatures. Thus, this strain represents 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).

A Gram-negative, aerobic, rod-shaped bacterium, designated DM2-R-LB4T was isolated from Cannabis sativa L. ‘Cheungsam’ in Andong, Republic of Korea. The strain DM2-R-LB4T grew at temperatures of 15–45 °C (optimum, 30–37 °C), pH of 5.5–9 (optimum, 8.0), and 0–2 % (w/v) NaCl concentration (optimum, 0%). Phylogenetic analyses based on the 16S rRNA gene sequences revealed that strain DM2-R-LB4T is related to species of the genus Sphingomonas , and shared 97.8 and 97.5% similarity to Sphingomonas kyenggiensis KCTC 42244T and Sphingomonas leidyi DSM 4733T, respectively. The DNA G+C content was 67.9 mol% and genome analysis of the strain DM2-R-LB4T revealed that the genome size was 4 386 171 bp and contained 4 009 predicted protein-coding genes. The average nucleotide identity (ANI) values between strain DM2-R-LB4T and S. kyenggiensis KCTC 42244T, and S. leidyi DSM 4733T was 76.8 and 76.7 %, respectively, while the values of digital DNA–DNA hybridization (dDDH) were 20.7 and 20.6 %, respectively. C14 : 0 2-OH, C16 : 0, and summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c) were the major fatty acids (>10 %) in the strain DM2-R-LB4T. The polar lipids comprised diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylcholine (PC), sphingoglycolipid (SGL), glycolipid (GL), phospholipid (PL), and two unidentified polar lipids (L1 and L2). Ubiquinone-10 (Q-10) was the only respiratory quinone. The polyamine pattern was found to contain homospermidine, putrescine, and spermidine. The results of phylogenetic anlayses, polyphasic studies, revealed that strain DM2-R-LB4T represents a novel species of the genus Sphingomonas , for which the name Sphingomonas cannabina sp. nov., is proposed. The type strain is DM2-R-LB4T (=KCTC 92075T = GDMCC 1.3018T).

A novel endophytic bacterial strain, designated GR-TSA-9T, was isolated from surface-sterilized grape (Vitis vinifera L.). 16S rRNA gene sequence analyses showed that the isolate was grouped within the genus Brevundimonas, displaying the highest similarity with Brevundimonas lenta DS-18T (97.9%) and Brevundimonas kwangchunensis KSL-102T (97.8%) and less than 97.5% similarity with other members of Brevundimonas. The strain GR-TSA-9T was a gram negative, rod shaped, facultatively anaerobic, catalase and oxidase positive, and motile bacterium. Its growth occurred at 10–37°C (optimally 25–30°C), at pH 7.0–8.0, and in NaCl 0–1% (optimally 0%). It contained ubiquinone-10 as a respiratory quinone, and the major cellular fatty acids (>10% of the total) were C16:0 (14.2%) and summed feature 8 (C18:1ω7c and/or C18:1ω6c, 65.6%). The polar lipids present in the strain were phosphoglycolipids, phosphatidylglycerol, 1,2-di-O-acyl-3-O-[d-glucopyranosyl-(1→4)-α-d-glucopyranuronosyl]glycerol, and unidentified lipids (L1, L2, and L4). The strain had one 2,976,716bp circular chromosome with a G+C content of 66.4%. The digital DNA–DNA hybridization value between strain GR-TSA-9T and B. lenta DS-18T was 20.9%, while the average nucleotide identity value was 76.7%. In addition, the dDDH and ANI values to other members in this genus, whose genome sequences are available, are less than 21.1 and 77.6%. Genome annotation predicted the presence of some gene clusters related to tyrosine degradation and pyomelanin formation. Strain GR-TSA-9T produced a brown melanin-like pigment in the presence of L-tyrosine-containing media. The highest pigment production (0.19g/L) was observed in tryptic soy broth with 1.0mg/ml L-tyrosine at 25°C for 6days of culture. Biophysical characterization by ultraviolet (UV)–visible spectroscopy, Fourier-transform infrared spectroscopy, and electrospray ionization mass spectrometry confirmed that the pigment was pyomelanin. Additionally, melanized GR-TSA-9T cells could protect the cells against UVC exposure. The phylogenetic, genomic, phenotypic, and chemotaxonomic features indicated that strain GR-TSA-9T represents a novel melanin-producing species of Brevundimonas. The type strain was GR-TSA-9T (KCTC 82386T=CGMCC 1.18820T).