title: Solid-state production of polygalacturonase by Aspergillus sojae ATCC 20235.
abstract: The effect of solid substrates, inoculum and incubation time were studied using response surface methodology (RSM) for the production of polygalacturonase enzyme and spores in solid-state fermentation using Aspergillus sojae ATCC 20235. Two-stage optimization procedure was applied using D-optimal and face-centered central composite design (CCD). Crushed maize was chosen as the solid substrate, for maximum polygalacturonase enzyme activity based on D-optimal design. Inoculum and incubation time were determined to have significant effect on enzyme activity and total spore (p<0.01) based on the results of CCD. A second order polynomial regression model was fitted and was found adequate for individual responses. All two models provided an adequate R(2) of 0.9963 (polygalacturonase) and 0.9806 (spores) (p<0.001). The individual optimum values of inoculum and incubation time for maximum production of the two responses were 2 x 10(7) total spores and 5-6 days. The predicted enzyme activity (30.55 U/g solid) and spore count (2.23 x 10(7)spore/ml) were very close to the actual values obtained experimentally (29.093 U/g solid and 2.31 x 10(7)spore/ml, respectively). The overall optimum region considering the two responses together, overlayed with the individual optima. Solid-state fermentation provided 48% more polygalacturonase activity compared to submerged fermentation under individually optimized conditions.
authors.affiliation: Biotechnology and Bioengineering Programme, Izmir Institute of Technology, Urla, Izmir 35430, Turkey.
authors.forename: Fatma Isik
authors.initials: FI
authors.lastname: Ustok
authors.forename: Canan
authors.initials: C
authors.lastname: Tari
authors.forename: Nihan
authors.initials: N
authors.lastname: Gogus
mesh_terms: D000704:Analysis of Variance; D001230:Aspergillus / Q000201:enzymology* / Q000235:genetics; D005285:Fermentation; D011096:Polygalacturonase / Q000096:biosynthesis* / Q000235:genetics; D012044:Regression Analysis; D015203:Reproducibility of Results; D013172:Spores, Fungal / Q000201:enzymology
chemical_list: D011096:Polygalacturonase