黄孢原毛平革菌木素过氧化物酶类在天然木素降解中作用的研究

STUDY OF THE ROLE OF LIGNIN PEROXIDASE PRODUCED BY PHANEROCHAETE CHRYSOSPORIUM IN DEPOLYMERIZATION OF NATURAL LIGNIN

通过诱变得到十一株木素过氧化物酶酶活降低的黄孢原毛平革菌（Ｐｈａｎｅｒｏｃｈａｅｔｅｃｈｒｙｓｏｓｐｏｒｉｕｍ）突变株，用灰色理论分析了其木素过氧化物酶类的产生与木素降解能力间的相关性，并从中筛选到一株木素过氧化物酶缺陷、锰过氧化物酶酶活明显降低的突变株，其木素降解能力为原始菌株的８０％左右。该菌粗酶液作用于纤维素酶酶解杉木木素和天然褐腐木素，可产生小分子的木素降解产物，此反应不需Ｈ２Ｏ２参与。红外光谱分析表明粗酶液对木素的作用主要为氧化作用。

hanerochaete chrysosporium produces two kinds of extracellular heme enzyme for lignin degradation, designated as Lignin peroxidase(LiP) and Mn-dependent peroxidase(MnP). LiP is generally considered to play a key role in lignin degradation. However some recent works suggested that the situation may not be so simple. In this study, a LiP-negative mutant(LiP-14), which maintained 10% of MnP activity of the wild type, was isolated and characterized. In the solid state fermentation, it could reduce the lignin content by 46%, while the wild type, 56%. The crude enzyme of LiP-14 was concentrated and reacted with cellulase treated lignin and/or brown-rot lignin. A small peak of lignin-derived compound of low molecular weight was observed by Sephadex LH-20 chromatography. This reaction did not require H 2O 2 as a catalyst, so there might be some ligninolytic enzyme fractions other than LiP and MnP in the crude enzyme of LiP-14.