Methanococcoides vulcani sp. nov., a marine methylotrophic methanogen that uses betaine, choline and N,N-dimethylethanolamine for methanogenesis, isolated from a mud volcano, and emended description of the genus Methanococcoides
2014
L’Haridon, Stéphane | Chalopin, Morgane | Colombo, Delphine | Toffin, Laurent
A novel, strictly anaerobic, methylotrophic marine methanogen, strain SLH33T, was isolated from deep sediment samples covered by an orange microbial mat collected from the Napoli Mud Volcano. Cells of strain SLH33T were Gram-stain-negative, motile, irregular cocci that occurred singly. Cells utilized trimethylamine, dimethylamine, monomethylamine, methanol, betaine, N,N-dimethylethanolamine and choline (N,N,N-trimethylethanolamine) as substrates for growth and methanogenesis. The optimal growth temperature was 30 °C; maximum growth rate was obtained at pH 7.0 in the presence of 0.5 M Na+. The DNA G+C content of strain SLH33T was 43.4 mol%. Phylogenetic analyses based on 16S rRNA gene sequences placed strain SLH33T within the genus Methanococcoides. The novel isolate was related most closely to Methanococcoides methylutens TMA-10T (98.8 % 16S rRNA gene sequence similarity) but distantly related to Methanococcoides burtonii DSM 6242T (97.6 %) and Methanococcoides alaskense AK-5T (97.6 %). DNA–DNA hybridization studies indicated that strain SLH33T represents a novel species, given that it shared less than 16 % DNA–DNA relatedness with Methanococcoides methylutens TMA-10T. The name Methanococcoides vulcani sp. nov. is proposed for this novel species, with strain SLH33T ( = DSM 26966T = JCM 19278T) as the type strain. An emended description of the genus Methanococcoides is also proposed.
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