Farshad Rahimpour - Biotechnology Research lab., Chemical Engineering Department, Faculty of Engineering, Razi University, ۶۷۱۴۹- ۶۷۳۴۶ Kermanshah, Iran
Gashaw Mamo - Department of Biotechnology, Center of Chemistry and Chemical Engineering, Lund University. P.O. Box ۱۲۴, SE- ۲۲۱ ۰۰ Lund, Sweden
Rajni Hatti-Kaul - Department of Biotechnology, Center of Chemistry and Chemical Engineering, Lund University. P.O. Box ۱۲۴, SE- ۲۲۱ ۰۰ Lund, Sweden

A PEG- phosphate aqueous two-phase system was used for purification of extracellular recombinant xylanase. Influence of the different factors affecting the partitioning of recombinant xylanase and contaminant proteins, like pH, polyethylene glycol (PEG) molecular weight, PEG and phase forming salt and NaCl concentration were studied using response surface methodology. After partitioning of xylanase, specific activity of xylanase was increased 6.71 times, and the enzyme yield of 82% was obtained.

extracellular xylanase; PEG-phosphate aqueous two-phase systems; central composition design; Purification; partitioning