Hippea maritima gen. nov., sp nov., a new genus of thermophilic, sulfur-reducing bacterium from submarine hot vents

Three strains of moderately thermophilic, sulfur-reducing bacteria were iso lated from shallow-water hot vents of the Bay of Plenty (New Zealand) and M atupi Harbour (Papua New Guinea). Cells of all isolates were short, Gram-ne gative, motile rods with one polar flagellum. All strains were obligate ana erobes and grew optimally at pH 5.8-6.2, 52-54 degrees C and 2.5-3 % (w/v) NaCl. Growth substrates were molecular hydrogen, acetate and saturated fatt y acids; one of the strains, isolated from Matupi Harbour, was able to util ize ethanol. Elemental sulfur was required for growth. H2S and CO2 were the only growth products. No growth occurred in the absence of 100 mg yeast ex tract l(-1). The G + C content of the DNA determined for the type strain MH 2T was 40.4 mol%. Results of 16S rDNA sequencing indicated that these strai ns represent a distinct lineage most closely related to the genus Desulfure lla. On the basis of the results of morphological, physiological and phylog enetic studies, a new genus, Hippea gen. nov., is proposed with the type sp ecies Hippea maritima gen. nov., sp. nov., of which the type strain is MH2T (= DSM 10411(T)).