Enzymes Produced during Brightening of Pulp by White-Rot Fungi

在固态发酵系统中，研究了黄孢平革菌和色板菌对硬木未漂白硫酸盐浆（LUKP）的生物漂白。对该体系中锰过氧化物酶（MnP）、木质素过氧化物酶（lignin peroxidase）和漆酶（漆酶）等氧化酶的累积活性进行测定，结果表明，该体系与黄孢霉和花斑霉的亮度增加与MnP累积活性呈线性关系。这一结果表明MnP参与了白腐菌对LUKP的增亮和脱木质素作用。另一方面，累积还原酶活性与纤维素的降解有关，而与木质素的降解无关。在体外，用部分纯化的黄孢霉MnP对未漂白的硫酸盐纸浆进行生物漂白。正常NUKP （NUKP- n，kappa值为28.4）和低木质素NUKP （NUKP- l，kappa值为18.3）分别经MnP处理3次后，其kappa值分别降低了60.6%、67.6和71.4%。结果表明，对于LUKP、NUKP-N和L， MnP处理和化学漂白（C/D-E-D）联合生物漂白工艺可使有效氯用量分别比常规漂白工艺（C/D-E-D- e - d）降低69.0、51.0和66.2%，获得85%亮度的矿浆。这表明MnP处理在减少纸浆漂白中氯基化学品的使用方面是有效的。

Biobleaching of hardwood unbleached kraft pulp (LUKP) by Phanerochaete chrysosporium and Trametes versicolor was studied in the solid-state fermentation system. When brightness increase and cumulative activities of oxidizing enzymes, manganese peroxidase (MnP), lignin peroxidase, and laccase, were determined, a linear relationship between brightness increse and cumulative MnP activity was found in this system with both P.chrysosporium and T.versicolor. This result suggests that MnP is involved in brightening and deligni-fication of LUKP by white-rot fungi.On the other hand, the cumulative reducing enzyme activity rather related to the degradation of cellulose than to that of lignin.In vitro, biobleaching of unbleached kraft pulps was performed with partial purified MnP from P.chrysosporium. When the LUKP (kappa number : 15.5) and two of softwood unbleached kraft pulp (NUKPs), normal NUKP (NUKP-N,kappa number : 28.4) and low-lignin-content NUKP (NUKP-L,kappa number : 18.3), were repeatedly treated three times with MnP,kappa number of each pulp decreased by 60.6,67.6, and 71.4%, respectively. As the result, the biobleaching process combined with MnP treatment and chemical bleaching (C/D-E-D) could reduce the amount of effective chlorine to obtain a pulp with 85% brightness by 69.0,51.0, and 66.2% compared with conventional bleaching process (C/D-E-D-E-D) for LUKP,NUKP-N,and L,respectively. This indicates that MnP treatment is effective in reducing the use of chloring-based chemicals in pulp bleaching.