Carboxydobrachium pacificum gen. nov., sp. nov., a new anaerobic, thermophilic, CO-utilizing marine bacterium from Okinawa Trough.

9 páginas.-- 3 figuras.-- referencias.-- El autor González Grau, Juan Miguel pertenece actualmente al Instituto de Recursos Naturales y Agrobiología de SevillaA new anaerobic, thermophilic, CO-utilizing marine bacterium, strain JMT, was isolated from a submarine hot vent in Okinawa Trough. Cells of strain JMT were non-motile thin straight rods, sometimes branching, with a cell wall of the Gram-positive type, surrounded with an S-layer. Chains of three to five cells were often observed. The isolate grew chemolithotrophically on CO, producing equimolar quantities of H2 and CO2 (according to the equation CO+H2O-->CO2+H2) and organotrophically on peptone, yeast extract, starch, cellobiose, glucose, galactose, fructose and pyruvate, producing H2, acetate and CO2. Growth was observed from 50 to 80 degrees C with an optimum at 70 degrees C. The optimum pH was 6.8-7.1. The optimum concentration of sea salts in the medium was 20.5-25.5 g l(-1). The generation time under optimal conditions was 7.1 h. The DNA G+C content was 33 mol %. Growth of isolate JMT was not inhibited by penicillin, but ampicillin, streptomycin, kanamycin and neomycin completely inhibited growth. The results of 16S rDNA sequence analysis revealed that strain JMT belongs to the Thermoanaerobacter phylogenetic group within the Bacillus-Clostridium subphylum of Gram-positive bacteria but represents a separate branch of this group. On the basis of morphological and physiological features and phylogenetic data, this isolate should be assigned to a new genus, for which the name Carboxydobrachium is proposed. The type species is Carboxydobrachium pacificum; the type strain is JMT (= DSM 12653T).The authors are grateful to G. A. Zavarzin and A. V. Lebedinsky, Institute of Microbiology, Russian Academy of Sciences, for helpful discussions. This work was supported by the Russian Foundation for Basic Research, grants nos 96-04-49463 and 99-04-48360, the ‘Biodiversity’ program of the Russian Ministry of Science and Technology, a NATO CLG grant to T. S. and F. T. R. and by NSF LEXEN Program support to F. T. R. and J. M. G.Peer reviewe