Xylanase production from Penicillium citrinum isolate HZN13 using response surface methodology and characterization of immobilized xylanase on glutaraldehyde-activated calcium-alginate beads.
The present study reports the production of high-level cellulase-free xylanase from Penicillium citrinum isolate HZN13. The variability in xylanase titers was assessed under both solid-state (SSF) and submerged (SmF) fermentation. SSF was initially optimized with different agro-waste residues, among them sweet sorghum bagasse was found to be the best substrate that favored maximum xylanase production (9643 U/g). Plackett-Burman and response surface methodology employing central composite design were used to optimize the process parameters for the production of xylanase under SSF. A second-order quadratic model and response surface method revealed the optimum conditions for xylanase production (sweet sorghum bagasse 25 g/50 ml; ammonium sulphate 0.36 %; yeast extract 0.6 %; pH 4; temperature 40 °C) yielding 30,144 U/g. Analysis of variance (ANOVA) showed a high correlation coefficient (R2= 97.63 %). Glutaraldehyde-activated calcium-alginate-immobilized purified xylanase showed recycling stability (87 %) up to seven cycles. Immobilized purified xylanase showed enhanced thermo-stability in comparison to immobilized crude xylanase. Immobilization kinetics of crude and purified xylanase revealed an increase in Km(12.5 and 11.11 mg/ml) and Vmax(12,500 and 10,000 U/mg), respectively. Immobilized (crude) enzymatic hydrolysis of sweet sorghum bagasse released 8.1 g/g (48 h) of reducing sugars. Xylose and other oligosaccharides produced during hydrolysis were detected by High-Performance Liquid Chromatography. The biomass was characterized by Scanning Electron Microscopy, Energy Dispersive X-ray and Fourier Transformation Infrared Spectroscopy. However, this is one of the few reports on high-level cellulase-free xylanase from P. citrinum isolate using sweet sorghum bagasse.
Department of Biochemistry, Karnatak University, Dharwad, 580 003, Karnataka, India.
Zabin K
ZK
Bagewadi
Department of Biochemistry, Karnatak University, Dharwad, 580 003, Karnataka, India.
Sikandar I
SI
Mulla
National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune, 411 007, Maharashtra, India.
Yogesh
Y
Shouche
Department of Biochemistry, Karnatak University, Dharwad, 580 003, Karnataka, India. hzninnekar@yahoo.com.
Harichandra Z
http://orcid.org/0000-0002-3435-6457
HZ
Ninnekar
Enzymatic hydrolysis; Immobilization; Penicillium citrinum; Response surface methodology; Sweet sorghum bagasse; Xylanase