Article Abstract:
The effects of kraft pulp and pulp bleaching on the overall metabolic carbon balance and the production of metabolites by white rot basidiomycete Trametes (Coriolus) versicolor is studied. Pulp related metabolic changes and biobleaching are observed. The presence of pulp or ligninolytic activity had little effect on overall carbon metabolism if free glucose was available. The presence of unbleached hardwood kraft pulp (HWKP) in a culture increases the culture's production of a number of acidic metabolites and stimulates the fungal secretion of the enzymes manganese peroxidase, cellulase and cellobiose-quinine oxidoreductase.
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Article Abstract:
Two distinct cellobiose dehydrogenases (CDH) isolated from the white rot fungus Trametes versicolor have molecular weights of 97 kDa and 81 kDa and isoelectric points of 4.2 and 6.4 respectively. The larger CDH (CDH 4.2) contains both flavin and heme as cofactors and the smaller CDH (CDH 6.4) contains only flavin. Both the CDH isoforms are specific for the beta-1,4 glycosidic bond and oxidize cellobiose as their preferred substrate, though cellotriose and lactose are also used. CDH 6.4 has a higher K(sub m) and a lower V(sub max) and turnover number than CDH 4.2, for all substrates.
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Article Abstract:
Oxidative stress in lignin peroxidase (LIP)-producing cultures of Phanerochaete chrysosporium is studied by comparing levels of reactive oxygen species (ROS), cumulative oxidative damage, and antioxidant enzymes with those found in non-LIP producing cultures exchange of atmospheric air. Results suggest that high levels of ROS, preferentially hydroxyl radicals, are required to trigger LIP synthesis.
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