Caldicoprobacter algeriensis sp. nov. a new thermophilic anaerobic, xylanolytic bacterium isolated from an algerian hot spring

Abstract

A thermophilic anaerobic bacterium (strain TH7C1 T ) was isolated from the hydrothermal hot spring of Guelma in the northeast of Algeria. Strain TH7C1 T stained Gram-positive, was a non-motile rod appearing singly, in pairs, or as long chains (0.7–1 9 2–6 l m 2 ). Spores were never observed. It grew at temperatures between 55 and 75 C (optimum 65 C) and at pH between 6.2 and 8.3 (optimum 6.9). It did not require NaCl for growth, but tolerated it up to 5 g l - 1 . Strain TH7C1 T is an obligatory heterotroph fermenting sugars including glucose, galactose, lactose, raffinose, fructose, ribose, xylose, arabinose, maltose, mannitol, cellobiose, mannose, melibiose, sac- charose, but also xylan, and pyruvate. Fermentation of sugars only occurred in the presence of yeast extract (0.1%). The end-products from glucose fermentation were acetate, lactate, ethanol, CO 2 , and H 2 . Nitrate, nitrite, thiosulfate, elemental sulfur, sulfate, and sulfite were not used as electron acceptors. The G ? C content of the genomic DNA was 44.7 mol% (HPLC techniques). Phy- logenetic analysis of the small-subunit ribosomal RNA (rRNA) gene sequence indicated that strain TH7C1 T was affiliated to Firmicutes , order Clostridiales , family Caldi- coprobacteraceae , with Caldicoprobacter oshimai (98.5%) being its closest relative. Based on phenotypic, phyloge- netic, and genetic characteristics, strain TH7C1 T is pro- posed as a novel species of genus Caldicoprobacter , Caldicoprobacter algeriensis , sp. nov. (strain TH7C1 T = DSM 22661 T = JCM 16184 T )