Browsing by Author "Kuwahara, Masaaki"

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    Lignin Peroxidase Production by Phanerochaete Chrysosporium Immobilized on Polyurethane Foam
    (2005-02) Nakamura, Yoshitoshi; Sawada, Tatsuro; Mtui, Godliving Y. S.; Kobayashi, Fumihisa; Kuwahara, Masaaki; Ito, Hiromichi
    Production of lignin peroxidase by a white-rot basidiomycete, Phanerochaete chrysosporium, was investigated experimentally using polyurethane foam as a carrier of immobilized fungal mycelia. The immobilized cell culture using polyurethane foam as a carrier of mycelia yielded significantly greater lignin peroxidase activity than the conventional stationary liquid culture. The effects of operational conditions, such as the kind and number of polyurethane foam cubes, glucose concentration and temperature, on the lignin peroxidase production were examined. Addition of 0.05% Tween 80, 1 mM veratryl alcohol and 1 mM FeSO4-·7H2O greatly improved the production of lignin peroxidase up to 2,700 units/ml culture medium. The lignin peroxidase activity in this culture was about three times larger than that obtained from the culture cultivated in the absence of these additives. Step change incubation lowering the temperature from 37°C to 30°C over an incubation time of three days was carried out for the large scale production of lignin peroxidase, and this incubation gave the highest lignin peroxidase activity 3,800 units/ml culture medium.
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    Lignin-degrading Enzyme Production by Bjerkandera Adusta Immobilized on Polyurethane Foam
    (1999-10) Nakamura, Yoshitoshi; Mtui, Godliving Y. S.; Sawada, Tatsuro; Kuwahara, Masaaki
    Production of the lignin-degrading enzymes lignin peroxidase (Lip), manganese peroxidase (MnP), and laccase (Lac) by the white-rot fungus Bjerkandera adusta was investigated experimentally using polyurethane foam (PUF) as a carrier of immobilized fungal mycelia. An immobilized cell culture with a low-nitrogen medium yielded significantly greater LiP, MnP, and Lac activities in comparison with those obtained in a liquid culture. The maximum activities of the three enzymes were 450, 370, and 100 U/ml, respectively, under the following incubation condition: glucose concentration, 20 g/l; temperature, 30°C; pH 4.5. The activities of MnP and Lac were significantly higher than those reported using other incubation methods. Lignin was degraded to the extent of 40% and its decolorization ratio was about 70% at an incubation time of 40 h using lignin-degrading enzymes from B. adusta. Six different isozymes of MnP were synthesized by B. adusta, two of which exhibited high MnP activity. Our preliminary finding that extracellular enzymes from B. adusta are capable of degrading and decoloring lignin makes these enzymes attractive for further research aimed at their large-scale application in lignin depolymerization, pulp biobleaching, and the degradation of toxic pollutants.