title: An extremely thermophilic anaerobic bacterium Caldicellulosiruptor sp. F32 exhibits distinctive properties in growth and xylanases during xylan hydrolysis.
abstract: An anaerobic, extremely thermophilic, and cellulose- and xylan-degrading bacterium F32 was isolated from biocompost. Sequence analysis of the 16S rRNA gene of this strain showed that it was closely related to Caldicellulosiruptor saccharolyticus DSM 8903 (99.0% identity). Physiological and biochemical data also supported that identification of strain F32 as a Caldicellulosiruptor species. The proteins secreted by Caldicellulosiruptor sp. F32 grown on xylan showed a xylanase activity of 7.74U/mg, which was 2.5 times higher than that of C. saccharolyticus DSM 8903. Based on the genomic sequencing data, 2 xylanase genes, JX030400 and JX030401, were identified in Caldicellulosiruptor sp. F32. The xylanase encoded by JX030401 shared 97% identity with Csac_0696 of C. saccharolyticus DSM 8903, while that encoded by JX030400 shared 94% identity with Athe_0089 of C. bescii DSM 6725, which was not found in the genome of strain DSM 8903. Xylanse encoded by JX030400 had 9-fold higher specific activity than JX030401. Our results indicated that although the 2 strains shared high identity, the xylanase system in Caldicellulosiruptor sp. F32 was more efficient than that in C. saccharolyticus DSM 8903.
authors.affiliation: Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Ying
authors.forename: Dongdong
authors.initials: D
authors.lastname: Meng
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Chen
authors.forename: Fuli
authors.initials: F
authors.lastname: Li
mesh_terms: D001421:Bacteria, Anaerobic / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D043364:Endo-1,4-beta Xylanases / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D005798:Genes, Bacterial; D006868:Hydrolysis; D007218:Industrial Microbiology; D007700:Kinetics; D010802:Phylogeny; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D013379:Substrate Specificity; D013696:Temperature; D014990:Xylans / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D014990:Xylans; D043364:Endo-1,4-beta Xylanases
keywords: Anaerobe; Caldicellulosiruptor sp.; Hyperthermophile; Lignocellulosic biomass; Xylanase