title: Extraction in aqueous two-phase systems of alkaline xylanase produced by Bacillus pumilus and its application in kraft pulp bleaching.
abstract: The aim of this work was to extract and to purify xylanase, produced by Bacillus pumilus from the crude fermentation broth, using aqueous two-phase systems (ATPS). The xylanase was extracted by partitioning in ATPS composed of phosphate and polyethylene glycol (PEG). The effect of tie-line length, PEG molecular mass and NaCl concentrations upon the purification factors and yields of xylanase were investigated by statistical design. The best system studied was that containing 22% PEG6000, 10% K2HPO4 and 12% NaCl with a purification factor of 33 and a 98% yield of enzyme activity. This system was also used for continuous extraction in a pulsed caps column. Subsequently, the xylanase from the crude fermentation broth was tested in hardwood kraft pulp bleaching.
authors.affiliation: Biochemical Engineering Laboratory, Chemical Engineering State University of Campinas, SP, Brazil.
authors.forename: M A
authors.initials: MA
authors.lastname: Bim
authors.forename: T T
authors.initials: TT
authors.lastname: Franco
mesh_terms: D000468:Alkalies / Q000737:chemistry; D001407:Bacillus / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D010209:Paper; D011092:Polyethylene Glycols / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D014867:Water / Q000737:chemistry; D043325:Xylan Endo-1,3-beta-Xylosidase; D014995:Xylosidases / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D000468:Alkalies; D014867:Water; D011092:Polyethylene Glycols; D012965:Sodium Chloride; D014995:Xylosidases; D043325:Xylan Endo-1,3-beta-Xylosidase