| Abstract |
Two bacterial strains, designated D10T and U8T, were isolated from soil samples from the Dong-angyeong cave and Geommeolle wharf sea-coast, Udo-Island, Jeju, South Korea. Both novel bacterial strains are yellow-pigmented, Gram-stain negative, motile by means of monotrichous flagella, short rod shaped and strictly aerobic. A phylogenetic tree was reconstructed based on their 16S rRNA gene sequences, which indicated that these two strains belong to the genus Lysobacter within the family Xanthomonadaceae. Strain D10T showed high 16S rRNA gene sequence similarities with Lysobacter humi FJY8T (99.0%), Lysobacter xinjiangensis RCML-52T (98.9%) and Lysobacter mobilis 9NM-14T (97.2%), whereas strain U8T showed high sequence similarities to L. mobilis 9NM-14T (97.9%), L. xinjiangensis RCML-52T (97.8%), L. humi FJY8T (97.5%) and Lysobacter bugurensis ZLD-29T (97.1%). The 16S rRNA gene sequence similarity between D10T and U8T was 97.0%. Strain D10T showed low DNA-DNA relatedness to U8T (57.7 ± 3.4%), L. humi FJY8T (48.8 ± 4.3%), L. xinjiangensis RCML-52T (60.1 ± 2.4%) and L. mobilis 9NM-14T (55.9 ± 1.9%). The level of DNA-DNA relatedness for strain U8T with respect to D10T, L. mobilis 9NM-14T, L. xinjiangensis RCML-52T, L. humi FJY8T, and L. bugurensis ZLD-29T was 55.5 ± 0.5%, 54.5 ± 2.1%, 58.1 ± 0.8%, and 51.9 ± 3.4%, respectively. The major polar lipids for both strains were identified as diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The major cellular fatty acids for both strains were identified as iso-C15:0, iso-C16:0 and summed feature 9 (iso-C17:1 ω9c/C16:0 10-methyl), and ubiquinone (Q-8) as the only isoprenoid quinone for both strains. The DNA G + C contents of the strains D10T and U8T were determined to be 70.2 mol% and 70.6 mol%. On the basis of phenotypic, genotypic, chemotaxonomic, and phylogenetic analysis, both strains D10T and U8T represent a novel species in the genus Lysobacter, for which the names Lysobacter helvus sp. nov. and Lysobacter xanthus sp. nov. are proposed, respectively. The type strain of L. helvus is D10T (= KCTC 62111T = JCM 32364T) and the type strain of L. xanthus is U8T (= KCTC 62112T = JCM 32365T).
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