Effect of white rot fungi variation on the biopulping of oil palm trunk

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Date
2014-08
Authors
Singh, Pooja
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Abstract
Lignocelluloses biomass is an important and sustainable natural resource for paper making. Wood the predominant source consists of flexible cellulose fibres, its pretreatment makes cellulose more accessible to enzymatic hydrolysis by modification of the lignin. Biological pulping is the treatment of lignocellulosic materials with oxidative lignin-degrading white rot fungi prior to pulping process. These microorganisms secrete enzymes that degrade lignin with minimum loss of polysaccharides. Though this pretreatment system is not well developed; but is advantageous over others because it does not burden the environment with harmful chemicals. Studies on biological pre-treatment have shown lignin loss, weight loss and improvement in paper quality. In the present study evaluation of the potential of four different white rot fungi namely Phanerochaete chrysosporium Burds, Trametes versicolor, Pycnoporus sanguineus (KUM70097) and Schizophyllum commune (KUM 793066) was conducted. They were chosen as they are well known inhabitant of tropical decomposing trees. The interest was to cultivate them on oil palm trunk as lignocellulosic substrate using solid state fermentation and determines their effect on paper making. After 28 days of pretreatment at 28±2°C with initial moisture content of 60% and constant aeration, the chips were harvested. Standard TAPPI methods, commonly used by the paper and pulp industry, were employed to determine the percentage cellulose, Klason lignin and extractives in the chips. These fungi produce xix ligninolytic enzymes, predominantly manganese peroxidase (MnP), lignin peroxidase (LiP), and laccase (Lac) in different combinations. The results supported the findings of others that white rots Phanerochaete chrysosporium, Trametes versicolor, Pycnoporus sanguineus and Schizophyllum commune can grow upon lignocellulosic substrates and produce considerable refining energy savings. The weight, lignin, cellulose and holocellulose loss was calculated and the extent of cell wall breakdown in combination with lignin modification was depicted from Scanning electron microscopy(SEM).The extent of bio delignification clearly shows the advantage of fungal pre-treatment in biopulping enhances production of enzymes, causing partial degradation of lignin and improving accessibility of cellulose. Additionally this study puts in evidence that oil palm biomass is a suitable substrate for biopulping and has potential for use in large-scale biotechnological processes. Considering all the four fungi and their performance overall in pulping and papermaking properties, Trametes versicolor can be considered to be the best amongst them. This fungi shows peak activities of lignocellulytic enzymes and in mechanical refining the chips pre-treated with T.versicolor consumed the least energy. After refining when pulp properties were studied it depicted that most of the mechanical properties were superior except for brightness. The Scanning electron microscopic examination revealed the development of cracks and collapse of cell walls. Thus due to afore mentioned qualities T.versicolor is found to be ideal for biopulping.
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White Rot
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