Application of fungi in biotechnological processes for the pulp and paper industry

English: Lignin, hemicellulose and cellulose occur together in wood and agricultural wastes that are used in industries such as the pulp and paper industry. Biodegradation could be applied by these industries to save cost and reduce environmental impact. Lignocellulose degradation is very complex and must be understood for the optimisation of biotechnological processes. White-rot fungi degrade lignin, cellulose and hemicellulose while brown-rot fungi modify lignin slightly, but also break down cellulose and hemicellulose. The most important enzymes in lignin degradation are manganese peroxidase, lignin peroxidase and laccase, which these fungi produce extracellularly. Decay fungi establish on organic material, which leads to the degradation of lignocellulose during the colonization process. A distinction must be made between primary and secondary colonisers during degradation, because of succession that takes place. Ophiostoma piliferum is an example of a primary coloniser, which is used to produce Cartapip 9if). This product was developed to treat wood chips during storage to reduce fibre degradation. The fungus was previously not available in South Africa because of a possible threat to local forest species. South African forestry companies wanted to test Cartapip 97® in industrial processes and it was, therefore, necessary to demonstrate that the fungus is not pathogenic. It also had to be confirmed that the fungus is a strain of 0. piliferum before certification and importation into South Africa would be allowed. Cultural and morphological characteristics of the anamorph of the Cartapip fungus were found to be similar to those of O. piliferum and it was released for field trials. The pathogenicity of the fungus was compared with Ophiostoma ips and Sphaeropsis sapinea, causes of sapstain on Pinus spp. in South Afiica, to demonstrate that O. piliferum does not pose a threat to forestry. Different pine species were inoculated and the results indicated that O. piliferum is not a pathogen and it is, therefore, safe to use Cartapip 9if) in South Afiica. Hardwood and softwood chips were subsequently treated with Cartapip 97® and pulped using different pulping methods, but the benefits were not obvious. It is, however, possible that the extractives content of the chips was reduced. A slight increase in strength of kraft pulp from softwood and hardwood and also of Soda-AQ pulp from A. mearnsii, was observed after pre-treatment with Cartapip 97®. Bagasse contains fibres that can be used for the production of paper. However, bagasse has to be stored for long periods during which time decay occurs. Stored bagasse could be pre-treated with fungi to preserve and possibly improve the quality of the bagasse. In this study, Lenzites betulina and Pycnoporus sanguineus were used to treat bagasse before pulping. Inoculum production, pulping processes and different incubation periods were evaluated to optimise biopulping. Ultrastructural studies of treated bagasse were used to determine the effect that fungal treatment has on bagasse. Pulping results obtained from bagasse treated with L. betulina were variable and P. sanguineus did not improve the pulping. These results indicated that colonisation and degradation strategies of biopulping fungi must be fully understood before an attempt is made to optimize pulping processes.