Studyi̇ng the effects of laccase on red pine kraft and waste paper pulp

Laccase is an enzyme that oxidizing phenolic substrates via using oxygen as a cofactor. The catalytic region of the enzyme includes three different types of coppermolecules that highly conserved. The stability of the laccase is quite higy because of the carbohydrates included in the enzyme structure. Some of the most important advantages of the laccase are existing in many different types of organisms and environments, and wide range of substrat specificity. These specificities make laccase an important enzyme for industrial applications. In this work we aimed to determine the effects of a bacterial laccase on bleaching of paper pulp. Cloning and expression of laccase into pMA0911 vector followed by paper bleaching analyses. Optimum temperature and pH of the enzyme was 60ºC and 4.5 respectively. Bleaching analyses were carried out with red pine Kraft pulp and waste paper pulp. Degredation zone, degredation rate and delignification rate were analysed. Delignification degree of waste water pulp was %5,1 and pine kraft pulp was %5,5. Some physical tests as laceration, soaking, blow out, grammage, thickness, intensity, rupture lenght and volume and optical tests were performed. The brightness of the paper was increased 56.86% for pine craft pulp and 56.77% for waste water pulp based on 12,97 kappa number. SEM was used for investigating the reducing effects of laccase on lignin.