Eubacterium maltosivorans sp. nov., a novel human intestinal acetogenic and butyrogenic bacterium with a versatile metabolism

A novel anaerobic, non-spore-forming bacterium was isolated from a faecal sample of a healthy adult. The isolate, designated strain YI T , was cultured in a basal liquid medium under a gas phase of H2/CO2 supplemented with yeast extract (0.1 g l -1 ). Cells of strain YI T were short rods (0.4-0.7×2.0-2.5 µm), appearing singly or in pairs, and stained Gram-positive. Catalase activity and gelatin hydrolysis were positive while oxidase activity, indole formation, urease activity and aesculin hydrolysis were negative. Growth was observed within a temperature range of 20-45 °C (optimum, 35-37 °C), and a pH range of 5.0-8.0 (optimum pH 7.0-7.5). Doubling time was 2.3 h when grown with glucose at pH 7.2 and 37 °C. Besides acetogenic growth, the isolate was able to ferment a large range of monomeric sugars with acetate and butyrate as the main end products. Strain YI T did not show respiratory growth with sulfate, sulfite, thiosulfate or nitrate as electron acceptors. The major cellular fatty acids of the isolate were C16 : 0 and C18 : 0. The genomic DNA G+C content was 47.8 mol%. Strain YI T is affiliated to the genus Eubacterium, sharing highest levels of 16S rRNA gene similarity with Eubacterium limosum ATCC 8486 T (97.3 %), Eubacterium callanderi DSM 3662 T (97.5 %), Eubacterium aggregans DSM 12183 T (94.4 %) and Eubacterium barkeri DSM 1223 T (94.8 %). Considering its physiological and phylogenetic characteristics, strain YI T represents a novel species within the genus Eubacterium, for which the name Eubacterium maltosivorans sp. nov. is proposed. The type strain is YI T (=DSM 105863 T =JCM 32297 T ).