Lysobacter fragariae sp. nov. and Lysobacter rhizosphaerae sp. nov. isolated from rhizosphere of strawberry plant

Abstract

Two bacterial strains, designated THG-DN8.7T and THG-DN8.3T, were isolated from the rhizosphere of a strawberry plant in Gyeryong Mountain, South Korea. Cells of both isolates were observed to be Gram-negative, yellow-coloured and rod-shaped. Comparative 16S rRNA gene sequence analysis showed that strain THG-DN8.7T had highest sequence similarities to Lysobacter yangpyeongensis KACC 11407T (97.2 %), Lysobacter niabensis KACC 11587T (97.0 %) and Lysobacter oryzae KCTC 22249T (96.9 %), while strain THG-DN8.3T had closely similarity with L. niabensis KACC 11587T (98.1 %), L. oryzae KCTC 22249T (97.1 %) and L. yangpyeongensis KACC 11407T (96.1 %). DNA–DNA relatedness values between strains THG-DN8.7T and THG-DN8.3T and their closest phylogenetically neighbours were below 30.0 %, which indicates that strains THG-DN8.7T and THG-DN8.3T represent distinct species within the genus Lysobacter. Both strains were found to contain iso-C15:0, iso-C16:0 and iso-C17:1ω9c as predominant fatty acids and ubiquinone-8 as major isoprenoid quinone. The major polar lipids were identified as phosphatidylethanolamine, phosphatidyl-N-methylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The DNA G+C content of strains THG-DN8.7T and THG-DN8.3T were determined to be 66.9 and 67.8 mol%, respectively. These data are consistent with the affiliation of the two new species represented by THG-DN8.7T and THG-DN8.3T to the genus Lysobacter. The names Lysobacter fragariae sp. nov. and Lysobacter rhizosphaerae sp. nov. are proposed for these species with the type strains THG-DN8.7T (=KCTC 42236T = JCM 30322T) and THG-DN8.3T (=KCTC 42237T = JCM 30321T), respectively.