Meiothermus cateniformans sp. nov., a slightly thermophilic species from north-eastern China

Two aerobic, non-motile and non-sporulating bacteria, strains LY1( T) and L462, were recovered from a hot spring located in the Qianshan area of north-eastern China. The novel strains had Gram-negative cell walls and grew at 30-66 degrees C (optimum 55-60 degrees C) and pH 5.5-10.0 (optimum pH 8.0-8.5). 16S rRNA gene sequence similarity analysis revealed that strains LY1( T) and L462 were most closely related to Meiothermus ruber ATCC 35948(T), M. taiwanensis WR-30(T) and M. cerbereus GY-1(T), with 97.1-98.4 % sequence similarity. Phylogenetic analysis indicated that the new isolates represented a novel species by forming a distinctive lineage within genus Meiothermus, which was confirmed by DNA-DNA reassociation values. Strain LY1( T) was obviously different from its closest relatives in a number of phenotypic characteristics, such as the inability to hydrolyse casein or to assimilate melibiose, trehalose, sucrose and lactose. Strain L462 was distinct in its ability to reduce nitrate. In addition, the novel strains were distinct in having larger amounts of anteiso-C(17 : 0) than their closest phylogenetic neighbours. On the basis of this polyphasic taxonomic characterization, the name Meiothermus cateniformans sp. nov. is proposed for the novel species, currently represented by the type strain LY1( T) (=CGMCC 1.6990(T) =JCM 15151(T)) and strain L462 (=CGMCC 1.6989 =JCM 15150).