Meiothermus hypogaeus sp. nov., a moderately thermophilic bacterium isolated from a hot spring

A novel moderately thermophilic, red-pigmented bacterium, designated strain AZM34c11(T), was isolated from the bottom of a 1000 m-deep drilled well located in a Japanese hot spring. Cells were Gram-negative and grew optimally at 50 °C, at pH 7.6 and with 0-0.3% (w/v) NaCl. Analysis of the 16S rRNA gene sequence revealed that the isolate belonged to the genus Meiothermus. Levels of 16S rRNA gene sequence similarity between strain AZM34c11(T) and the type strains of recognized Meiothermus species were 88.2-94.8%. Strain AZM34c11(T) was distinguished from recognized Meiothermus species by its cellular fatty acid profile: iso-C(16:0) was one of the predominant components and hydroxy fatty acids were present only in trace amounts. The strain could also be differentiated based on its growth substrate preferences and characteristic enzyme reactions. On the basis of these results, strain AZM34c11(T) is considered to represent a novel species of the genus Meiothermus, for which the name Meiothermus hypogaeus sp. nov. is proposed. The type strain is AZM34c11(T) (=NBRC 106114(T) =DSM 23238(T)).