title: Production of cellulase-free xylanase by the recombinant Bacillus subtilis and its applicability in paper pulp bleaching.
abstract: A metagenomic xylanase gene (Mxyl) was successfully cloned into shuttle vector pWH1520 and expressed in Bacillus subtilis extracellularly. On induction with xylose, recombinant xylanase secretion commenced after 6 h. Identifying critical variables for recombinant xylanase production by one-variable-at-time approach followed by optimization of the selected variables (xylose, inoculum density, incubation density) by response surface methodology (RSM) led to three-fold enhancement in extracellular xylanase production (119 U mL(-1) ). When the pulp was treated with recombinant xylanase at 80°C and pH 9.0, kappa number of the pulp was reduced with concomitant increase in brightness and 24% reduction in chlorine consumption. This is the first report on the expression of metagenomic xylanase gene in Bacillus subtilis extracellularly and its utility in developing an environment-friendly pulp bleaching process.
authors.affiliation: Dept. of Microbiology, University of Delhi South Campus, New Delhi, 110021, India.
authors.forename: Digvijay
authors.initials: D
authors.lastname: Verma
authors.forename: T
authors.initials: T
authors.lastname: Satyanarayana
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics*; D002480:Cellulase / Q000737:chemistry; D003001:Cloning, Molecular; D043364:Endo-1,4-beta Xylanases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D054892:Metagenome; D011994:Recombinant Proteins; D014994:Xylose / Q000737:chemistry / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D014994:Xylose; D002480:Cellulase; D043364:Endo-1,4-beta Xylanases
keywords: Bacillus subtilis; heterologous expression; metagenomic xylanase; pulp bleaching