Enzymes Produced during Brightening of Pulp by White-Rot Fungi

采用黄孢原毛革菌和杂色栓菌对阔叶木未漂硫酸盐浆进行了固态发酵漂白研究。当白度增加和氧化酶，锰过氧化物酶（MnP），木质素过氧化物酶和漆酶的累积活性的测定，白度增加和累积的MnP活性之间的线性关系被发现在这个系统与P.chrysosporium和T. versicolor。结果表明，MnP参与了白腐菌对LUKP的增白和脱木素作用，而累积还原酶活性与纤维素的降解有关，而与木素的降解无关。当用MnP对LUKP（卡伯值为15.5）、普通NUKP（NUKP-N，卡伯值为28.4）和低木素NUKP（NUKP-L，卡伯值为18.3）两种针叶木未漂硫酸盐浆（NUKPs）重复处理3次时，每种浆的卡伯值分别降低60.6，67.6和71.4%。结果表明，与常规漂白工艺（C/D-E-D-E-D）相比，LUKP、NUKP-N和L的生物漂白工艺（C/D-E-D-E-D）在获得85%白度时的有效氯用量分别降低了69.0%、51.0%和66.2%。这表明MNP处理在减少纸浆漂白中基于氯化的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.