A nostoxanthin-producing bacterium, Sphingomonas nostoxanthinifaciens sp. nov., alleviates the salt stress of Arabidopsis seedlings by scavenging of reactive oxygen species

Lingmin Jiang; Jiyoon Seo; Yuxin Peng; Doeun Jeon; Ju Huck Lee; Cha Young Kim; Jiyoung Lee

doi:10.3389/fmicb.2023.1101150

A nostoxanthin-producing bacterium, Sphingomonas nostoxanthinifaciens sp. nov., alleviates the salt stress of Arabidopsis seedlings by scavenging of reactive oxygen species

Front Microbiol. 2023 Feb 10:14:1101150. doi: 10.3389/fmicb.2023.1101150. eCollection 2023.

Authors

Lingmin Jiang¹, Jiyoon Seo¹, Yuxin Peng¹, Doeun Jeon¹, Ju Huck Lee¹, Cha Young Kim¹, Jiyoung Lee¹

Affiliation

¹ Biological Resource Center, Korean Collection for Type Cultures (KCTC), Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup, Republic of Korea.

Abstract

A novel, nostoxanthin-producing, endophytic bacterium, designated as AK-PDB1-5^T, 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 MIMD3^T (95.6%) and Sphingomonas jatrophae S5-249^T (95.3%) of the family Sphingomonadaceae. Strain AK-PDB1-5^T 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-PDB1-5^T 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-PDB1-5^T contained C_14:0 2OH_, C_16:0 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-PDB1-5^T 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-PDB1-5^T was determined to be a novel species in the genus Sphingomonas with the proposed name Sphingomonas nostoxanthinifaciens sp. nov. The type strain is AK-PDB1-5^T (= KCTC 82822^T = CCTCC AB 2021150^T).

Keywords: Abies koreana; antiSMASH; orthologous average nucleotide identity; phylogeny; polyphasic taxonomy; whole-genome annotation.