Abstract

Two novel Gram-stain negative, non-motile, rod-shaped and aerobic bacterial strains, designated YIM 77920(T) and YIM 77921(T), were isolated from freshwater sediment of Jiuxiang cave, a tourism cave located in Yiliang county, Yunnan province, south-west China. The 16S rRNA gene sequences of strains YIM 77920(T) and YIM 77921(T) exhibited sequence similarities of 96.59 and 96.66 % to Hymenobacter xinjiangensis X2-Y-T, respectively, and indicated that the two isolates belong to the genus Hymenobacter. The major fatty acids present in the two strains were identified as C-16:1 omega 5c, iso-C-15:0 and Summed Feature 4 (C-17:1 anteiso B/iso I). MK-7 was identified as the respiratory quinone component for both strains. The polar lipids profile of strain YIM 77920(T) was found to consist of phosphatidylethanolamine, four unidentified polar lipids, three unidentified aminophospholipids, two unidentified phospholipids and two unidentified aminolipids, while that of strain YIM 77921(T) consisted of phosphatidylethanolamine, four unidentified polar lipids, two unidentified aminolipids, one unidentified phospholipid and four unidentified aminophospholipids. The DNA G+C contents of strains YIM 77920(T) and YIM 77921(T) were determined to be 57.5 and 59.6 mol%, respectively. DNA-DNA hybridization between them had a low value (56.55 %). Based on the morphological and physiological properties, and phylogenetic analyses, strains YIM 77920(T) and YIM 77921(T) are considered to represent two novel species of the genus Hymenobacter, for which the names Hymenobacter latericoloratus sp. nov. (type strain YIM 77920(T) = JCM 30327(T) = CCTCC AB 2012949(T)) and Hymenobacter luteus sp. nov. (type strain YIM 77921(T) = JCM 30328(T) = CCTCC AB 2012947(T)) are proposed.