การปรับสภาพเบื้องต้นไม้ยูคาลิปตัสโดยใช้ราเน่าขาวสายพันธุ์เขตร้อนเพื่อผลิตเยื่อแบบคราฟต์ / วริษฐา ศรีแพทย์ = Pretreatment of eucalyptus wood using tropical strains of white rot fungi for kraft pulping / Varidtha Sripat
Screening of tropical white rot fungi from Thailand for biopretreatment of Eucalyptus wood was investigated. Fourteen isolates of white rot fungi were cultivated and their ligninolytic and cellulase production were tested using plate screening assay with solid lignin/cellulose modified basal media. Of these, 3 isolates (SK7, CUT3 and KK16) exhibited high ligninase and low cellulase production which are suitable for pretreatment in the next step. The highest lignin loss was found in SK7, CUT3 and KK16 at 19.59%, 18.49% and 15.45%, respectively, when three isolates were used to treat Eucalyptus wood chip for 15 days. In quantitative assayed for ligninolytic enzyme, SK7 showed the highest laccase at values 0.1532 Unit/ml. And also produced manganese peroxidase and ligninperoxidase in testing. For the optimal condition for wood chip pretreatment by selected white rot fungus (SK7) with kraft pulping at 25% effective alkaline and 25% sulfidity, The addition of inoculation size and incubation time trended to increase the tensile index and residual alkali. In addition, using of regression equation to predict the relationship between factors and responses values exhibited the highest percentage of tensile index and residual alkaline at 5% and 23.47%, respectively, after incubation for 25 days with 100 mg dry weight of inoculation size. Decreasing the size of wood chip further improved the tensile index with 2.01 folds compared to the original size after pretreatment and also reduced the alkali consumption. This could lead to chemicals and energy saving in pulping process. In addition, the efficiency of wood chip pretreatment from selected fungus was similar to the reference strain (P. chrysosporium) in case of strength properties and residual alkaline.