title: Optimization of lignin peroxidase production and stability by Phanerochaete chrysosporium using sewage-treatment-plant sludge as substrate in a stirred-tank bioreactor.
abstract: A laboratory-scale study was carried out to produce lignin peroxidase (ligninase) by white rot fungus (Phanerochaete chrysosporium) using sewage-treatment-plant (STP) sludge as the major substrate. The optimization was done using full-factorial design (FFD) with agitation and aeration as the two parameters. Nine experiments indicated by the FFD were fermented in a stirred-tank bioreactor for 3 days. A second-order quadratic model was developed using the regression analysis of the experimental results with the linear, quadratic, and interaction effects of the parameters. Analysis of variance (ANOVA) showed a high coefficient of determination (R (2)) value of 0.972, thus indicating a satisfactory fit of the quadratic model with the experimental data. Using statistical analysis, the optimum aeration and agitation rates were determined to be 2.0 vvm and 200 rpm, respectively, with a maximum activity of 225 U l(-1) in the first 3 days of fermentation. The validation experiment showed the maximum activity of lignin peroxidase was 744 U l(-1) after 5 days of fermentation. The results for the tests of the stability of lignin peroxidase showed that the activity was more than 80% of the maximum for the first 12 h of incubation at an optimum pH of 5 and temperature of 55 degrees C.
authors.affiliation: Department of Biotechnology Engineering, Faculty of Engineering, International Islamic University Malaysia, Gombak, Kuala Lumpur, Malaysia. zahangir@iium.edu.my
authors.forename: Md Zahangir
authors.initials: MZ
authors.lastname: Alam
authors.forename: Mariatul F
authors.initials: MF
authors.lastname: Mansor
authors.forename: K C A
authors.initials: KC
authors.lastname: Jalal
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D046508:Culture Techniques / Q000379:methods*; D004795:Enzyme Stability; D007700:Kinetics; D010544:Peroxidases / Q000737:chemistry* / Q000378:metabolism*; D020075:Phanerochaete / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D012722:Sewage; D010544:Peroxidases; C042858:lignin peroxidase