Lysobacter helvus sp. nov. and Lysobacter xanthus sp. nov., isolated from Soil in South Korea

Abstract

Two bacterial strains, designated D10(T) and U8(T), 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 D10(T) showed high 16S rRNA gene sequence similarities with Lysobacter humi FJY8(T) (99.0%), Lysobacter xinjiangensis RCML-52(T) (98.9%) and Lysobacter mobilis 9NM-14(T) (97.2%), whereas strain U8(T) showed high sequence similarities to L. mobilis 9NM-14(T) (97.9%), L. xinjiangensis RCML-52(T) (97.8%), L. humi FJY8(T) (97.5%) and Lysobacter bugurensis ZLD-29(T) (97.1%). The 16S rRNA gene sequence similarity between D10(T) and U8(T) was 97.0%. Strain D10(T) showed low DNA-DNA relatedness to U8(T) (57.7 +/- 3.4%), L. humi FJY8(T) (48.8 +/- 4.3%), L. xinjiangensis RCML-52(T) (60.1 +/- 2.4%) and L. mobilis 9NM-14(T) (55.9 +/- 1.9%). The level of DNA-DNA relatedness for strain U8(T) with respect to D10(T), L. mobilis 9NM-14(T), L. xinjiangensis RCML-52(T), L. humi FJY8(T), and L. bugurensis ZLD-29(T) 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-C-15:0, iso-C-16:0 and summed feature 9 (iso-C-17:1 omega 9c/C-16:0 10-methyl), and ubiquinone (Q-8) as the only isoprenoid quinone for both strains. The DNA G+C contents of the strains D10(T) and U8(T) were determined to be 70.2mol% and 70.6mol%. On the basis of phenotypic, genotypic, chemotaxonomic, and phylogenetic analysis, both strains D10(T) and U8(T) 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 D10(T) (=KCTC 62111(T)=JCM 32364(T)) and the type strain of L. xanthus is U8(T) (=KCTC 62112(T)=JCM 32365(T)).