Isolation and characterization of a thermophilic Methanobacterium able to use formate,the strain FTF

A thermophilic anaerobic which produced methane from formate and H₂ and CO₂ was isolated from a bench-scale digester treating a mixture of solid wastes at 55°C, after enrichment cultures on sodium acetate. The cells were slightly crooked rods occurring singly or in filaments. The bacterium was not motile, and stained Gram positive. Colonies appearing after 1 week of incubation were white with filamentous edges and 1 mm in diameter. The organism used H₂:CO₂ or formate as an energy source. Yeast extract was not required but stimulated growth significantly. Casamino acids were stimulatory and could serve as a nitrogen source. Cysteine was used as a sulfur source. The optimum pH for growth was 7.5. Growth occurred from 35 to 70°C with an optimum at 55°C. The deoxyribonucleic acid base composition was 49.2 mol% guanine plus cytosine. Though this isolate conforms to Methanobacterium thermoformicium, its proper assignment awaits further studies. It has been deposited in the Deutsche Sammlung von Mikroorganismen as strain DSM 3012.This work was supported in part by the Conseil Régional Nord/Pas-de-Calais