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 YIT, was cultured in a basal liquid medium under a gas phase of H2/CO2 supplemented with yeast extract (0.1g l1). Cells of strain YIT were short rods (0.40.7×2.02.5µm), 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 2045°C (optimum, 3537°C), and a pH range of 5.08.0 (optimum pH 7.07.5). Doubling time was 2.3h 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 YIT 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+Ccontent was 47.8mol%. Strain YIT is affiliated to the genus Eubacterium , sharing highest levels of 16S rRNA gene similarity with Eubacterium limosum ATCC 8486T (97.3%), Eubacterium callanderi DSM 3662T (97.5%), Eubacterium aggregans DSM 12183T (94.4%) and Eubacterium barkeri DSM 1223T (94.8%). Considering its physiological and phylogenetic characteristics, strain YIT represents a novel species within the genus Eubacterium , for which the name Eubacterium maltosivorans sp. nov. is proposed. The type strain is YIT (=DSM 105863T=JCM 32297T).This work was supported by the SIAM Gravitation Grant 024.002.002 of the Netherlands Organization for Scientific Research.