Abstract
Among a large collection of Tunisian hot springs bacterial isolates a bacterial strain, THE22(T), with xylanolytic properties was identified. The bacterium was isolated from a natural hot spring Ain Echefa at Mediteranean sea (Korbous, North-Eastern Tunisia). The novel strain was Gram positive, spore-forming, rod-shaped, facultatively anaerobic and grew optimally under conditions of 55 degrees C, 1% (w/v) NaCl and pH 7-8. The 16S rRNA gene sequence analysis showed that strain THE22(T) fell within the radiation of the cluster comprising Paenibacillus species with Paenibacillus phyllosphaerae PALXIL04(T) as the closest phylogenetic neighbour (95.8%). The predominant components in the fatty methyl ester profile were iso-C-16:0 (34.46%), C-16:0 (19.64%), anteiso-C-15:0 (19.18%) and anteiso-C-17:0 (18.11%). The major respiratory quinone was menaquinone-7 (MK-7). The diamino acid found in the cell-wall peptidoglycan was meso-diaminopimelic acid. The base composition of DNA was 56 mol%. Based on the polyphasic taxonomic data, strain THE-22(T) (=DSM 18499(T)=LMG 23758(T)) was recognized as a novel species within the genus Paenibacillus. The name Paenibacillus marinum sp. nov. is proposed.