title: Optimization of medium composition for alkali-stable xylanase production by Aspergillus fischeri Fxn 1 in solid-state fermentation using central composite rotary design.
abstract: Response surface methodology and central composite rotary design (CCRD) was employed to optimize a fermentation medium for the production of alkali-stable cellulase-free xylanase by Aspergillus fischeri in solid-state fermentation at pH 9.0 with wheat bran as substrate. The four variables involved in this study were sodium nitrite, potassium dihydrogen phosphate, magnesium sulphate and yeast extract. The statistical analysis of the results showed that, in the range studied, only sodium nitrite had a significant effect on xylanase production. The optimized medium containing (in g/l) NaNO(2)-7.0, K2HPO(4)-1.0, MgSO(4)-0.5 and yeast extract-5.0 resulted in 1.9-fold increased level of alkali-stable xylanase (1024 U/g wheat bran) production compared to initial level (540 U/g) after 72 h of fermentation, whereas its value predicted by the quadratic model was 931 U/g. The level of protease activity was considerably decreased in optimized medium, thus helping to preserve the xylanase activity and demonstrating another advantage of applying statistical experimental design.
authors.affiliation: Department of Microbial Technology, School of Biological Sciences, Centre for Excellence in Genomic Sciences, Madurai Kamaraj University, Madurai 625 021, India.
authors.forename: S R
authors.initials: SR
authors.lastname: Senthilkumar
authors.forename: B
authors.initials: B
authors.lastname: Ashokkumar
authors.forename: K
authors.initials: K
authors.lastname: Chandra Raj
authors.forename: P
authors.initials: P
authors.lastname: Gunasekaran
mesh_terms: D001230:Aspergillus / Q000201:enzymology*; D003470:Culture Media / Q000737:chemistry; D043364:Endo-1,4-beta Xylanases / Q000096:biosynthesis*; D004795:Enzyme Stability; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D013997:Time Factors
chemical_list: D003470:Culture Media; D043364:Endo-1,4-beta Xylanases