Caldicoprobacteralgeriensis sp. nov. a New Thermophilic Anaerobic, Xylanolytic Bacterium Isolated from an Algerian Hot Spring

A thermophilic anaerobic bacterium (strain TH7C1T) was isolated from the hydrothermal hot spring of Guelma in the northeast of Algeria. Strain TH7C1T stained Gram-positive, was a non-motile rod appearing singly, in pairs, or as long chains (0.7–1 × 2–6 μm2). 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 TH7C1T is an obligatory heterotroph fermenting sugars including glucose, galactose, lactose, raffinose, fructose, ribose, xylose, arabinose, maltose, mannitol, cellobiose, mannose, melibiose, saccharose, 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, CO2, and H2. 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). Phylogenetic analysis of the small-subunit ribosomal RNA (rRNA) gene sequence indicated that strain TH7C1T was affiliated to Firmicutes, order Clostridiales, family Caldicoprobacteraceae, with Caldicoprobacteroshimai (98.5%) being its closest relative. Based on phenotypic, phylogenetic, and genetic characteristics, strain TH7C1T is proposed as a novel species of genus Caldicoprobacter, Caldicoprobacter algeriensis, sp. nov. (strain TH7C1T = DSM 22661T = JCM 16184T).