title: Highly thermo-halo-alkali-stable β-1,4-endoxylanase from a novel polyextremophilic strain of Bacillus halodurans.
abstract: A novel bacterial isolate, capable of producing extracellular highly thermostable, halo-alkali-stable and cellulase-free xylanase, was isolated from soil and identified as Bacillus halodurans TSPV1 by polyphasic approach. The Plackett-Burman design identified wheat bran, lactose, tryptone and NaCl as the factors that significantly affect xylanase production, and thus, these were optimized by response surface methodology. The data analysis suggested that optimum levels of wheat bran (15-20 g L(-1)), lactose (1.0-1.5 g L(-1)), tryptone (2-2.5 g L(-1)) and NaCl (7.0-8.0 g L(-1)) support 6.75-fold higher xylanase production than that in the un-optimized medium. The xylanase is optimally active at 90 °C and pH 10, and stable for 4 h at 90 °C (T 1/2 60 h) over a broad range of NaCl concentrations (0-29 %). This is the first report on the isolation of polyextremophilic B. halodurans strain that produces thermo-halo-alkali-stable xylanase in submerged fermentation. This enzyme efficiently saccharifies agro residues like wheat bran and corncobs. Fifty-six percent of hemicellulose of wheat bran could be hydrolyzed by xylanase (100 U g(-1) substrate) along with cellulase (22 U FPase and 50 U CMCase g(-1)). The xylanase, being thermo-alkali stable and cellulase free, can find applications in pre-bleaching of paper pulps and hydrolysis of xylan in agricultural residues.
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110021, India, vikash.udsc@gmail.com.
authors.forename: Vikash
authors.initials: V
authors.lastname: Kumar
authors.forename: Poonam
authors.initials: P
authors.lastname: Syal
authors.forename: T
authors.initials: T
authors.lastname: Satyanarayana
mesh_terms: D001407:Bacillus / Q000201:enzymology* / Q000254:growth & development; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry; D004043:Dietary Fiber; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000378:metabolism*; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D012965:Sodium Chloride / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D004043:Dietary Fiber; D011134:Polysaccharides; D012965:Sodium Chloride; C007916:hemicellulose; D043364:Endo-1,4-beta Xylanases