Sunday, August 1, 2010
Pacific Concourse (Hyatt Regency San Francisco)
The production of xylanase from palm kernel cake (PKC) as a substrate in solid substrate fermentation (SSF) was studied using a laboratory packed-bed bioreactor. The simultaneous effects of three independent variables, namely incubation temperature, initial moisture content of substrate and airflow rate on xylanase production were evaluated by response surface methodology (RSM) on the basis of central composite face centered (CCF) design. Eighteen trials were conducted in which Aspergillus niger FTCC 5003 was cultivated on PKC in an aerated column bioreactor for 7 days under SSF process. The highest level of xylanase (174.88 U/g) was obtained when SSF process was performed at incubation temperature, initial moisture level and aeration rate of 25 oC, 60 % and 1.5 l/min, respectively. Statistical analysis revealed that linear effect of incubation temperature and the quadratic term of initial moisture content had significant effects on the production of xylanase (P< 0.01). Similar analysis also demonstrated that the interaction effect between incubation temperature and moisture level and the interaction effect between initial moisture content and aeration rate significantly influenced the production of xylanase (P< 0.05). Statistical model suggested that the optimal conditions for attaining the highest level of xylanase were incubation temperature of 25.22 oC, initial moisture level of 63 % and aeration rate of 2.25 l/min.