Fungal oxidative enzymes, such as peroxidases and laccases, are the key catalysts in lignin biodegradation in vivo, and consequently provide an important source for industrial ligninolytic biocatalysts. Recently, it has been shown that some syringyl-type phenolics have potential as industrial co-oxidants or mediators, both in laccase and peroxidase catalyzed modifications of lignocellulosic material. A great deal of research in this area is performed on different types of model systems requiring application of solvent combinations that produce difficulties for example in terms of precipitation of substrates and reaction products.<br/>We have now developed a new type of reaction system based on the oxidation of dehydrogenation polymer, DHP, in cellulose slurry more closely resembling natural lignocellulose, and this cellulose bound DHP material was treated as substrate in oxidoreductase-mediator –system with isolation by simple solvent extraction to give oxidized low and high molecular weight fractions for further analysis. In these experiments, the DHP was oxidized in the presence of oxidoreductases from white-rot fungi:  laccase from Trametes villosa (NS 51002) and two peroxidases, manganese peroxidase from Phlebia sp. Nf b19 and versatile peroxidase (VP) from Bjerkandera adusta under mediative oxidation conditions. After isolation, the high molecular fractions of SG-DHP were analyzed by standard solution state NMR procedures (1H, 13C, HSQC, HMBC), 31P NMR, and SEC The structural analysis of the oxidized polymers show clear modifications in the polymer outcome, e.g. markedly reduce the average molecular weight of the samples with apparent structural deformations in the side-chain area.<br/>

Method for studies of oxidoreductase catalyzed oxidation of synthetic lignin in presence of co-oxidants

249th National Meeting (2015)

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