Abstract

A mesophilic, facultative, anaerobic, xylanolytic-cellulolytic bacterium, TW1T, was isolated from sludge in an anaerobic digester fed with pineapple waste. Cells stained Gram-positive, were spore-forming, and had the morphology of straight to slightly curved rods. Growth was observed in the temperature range of 30 to 50°C (optimum 37°C) and the pH range of 6.0 to 7.5 (optimum pH 7.0) under aerobic and anaerobic conditions. The strain contained meso-diaminopimelic acid in the cell-wall peptidoglycan. The predominant isoprenoid quinone was menaquinone with seven isoprene units (MK-7). Anteiso-C15:0, iso-C16:0, anteiso-C17:0, and C16:0 were the predominant cellular fatty acids. The G+C content of the DNA was 49.5 mol%. A phylogenetic analysis based on 16S rRNA showed that strain TW1T belonged within the genus Paenibacillus and was closely related to Paenibacillus cellulosilyticus LMG 22232T, P. curdlanolyticus KCTC 3759T, and P. kobensis KCTC 3761T with 97.7, 97.5, and 97.3% sequence similarity, respectively. The DNA-DNA hybridization values between the isolate and type strains of P. cellulosilyticus LMG 22232T, P. curdlanolyticus KCTC 3759T, and P. kobensis KCTC 3761T were found to be 18.6, 18.3, and 18.0%, respectively. The protein and xylanase patterns of strain TW1T were quite different from those of the type strains of closely related Paenibacillus species. On the basis of DNA-DNA relatedness and phenotypic analyses, phylogenetic data and the enzymatic pattern presented in this study, strain TW1T should be classified as a novel species of the genus Paenibacillus, for which the name Paenibacillus xylaniclasticus sp. nov. is proposed. The type strain is TW1T (=NBRC 106381T =KCTC 13719T =TISTR 1914T).

• Keywords: anaerobic digester; facultative anaerobic bacterium; Paenibacillus xylaniclasticus; xylanase; xylanolytic-cellulolytic bacterium