Browsing by Author "DURAN, N"

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    DECOLORIZATION OF KRAFT EFFLUENT BY FREE AND IMMOBILIZED LIGNIN PEROXIDASES AND HORSERADISH-PEROXIDASE
    (1991) FERRER, I; DEZOTTI, M; DURAN, N
    Color removal from Kraft effluent by lignin peroxidase and horseradish peroxidase was compared. Free lignin peroxidase and horseradish peroxidase removed color from kraft effluent. Immobilization of lignin peroxidase type III, lyophilized fungal culture and horseradish peroxidase on CNBr-Sepharose 4B improved the decolorization by factor of 2.9, 4.5 and 2.6, respectively in 48 h. Lignin peroxidase type I was effective only in the immobilized form in decolorization. In general, the immobilized form all the studied systems exhibited an average value around of 30% polymer consumption and very little of depolymerization. Lignin peroxidases and lyophilized fungal culture were shown to have considerable potential for treating Kraft effluents.
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    LIGNIN PEROXIDASE FROM CHRYSONILIA-SITOPHILA - HEAT-DENATURATION KINETICS AND PH STABILITY
    (1992) FERRER, I; ESPOSITO, E; DURAN, N
    Many practical applications utilizing lignin peroxidases from Chrysonilia sitophila (TFB-27441 strain) have been proposed. However, more information regarding the stability of these enzymes was required to design and develop these technologies. Heat- and pH-denaturation studies were conducted on purified lignin peroxidase and on crude culture of lignin peroxidase from C. sitophila. The culture produced in a 15-l bioreactor with Fries medium was utilized to obtain purified lignin peroxidases. LIG-I, LIG-II, and LIG-III were tested in the range 28-50-degrees-C, and LIG-III was found to be the most stable in the temperature range tested. The observed k(D) values at 28, 35, and 50-degrees-C were 0.058, 0.095, and 0.111 h-1, respectively. Increasing the LIG-III concentration by 2.3-fold increased thermal stability by around twofold. The heat-denaturation kinetics under these conditions for all lignin peroxidases and for the crude culture were first-order. LIG-I and LIG-II appeared as the most representative enzymes in the crude culture, since similar k(D) values were obtained. The pH stability showed the same trends.
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    LIGNINASES FROM CHRYSONILIA-SITOPHILA (TFB-27441 STRAIN)
    (1987) DURAN, N; FERRER, I; RODRIGUEZ, J