Biological processing of pine logs with Phlebiopsis gigantea for pulp and paper production

Biological processing of red pine logs with Phlebiopsis gigantea for the pulp and paper industries was successfully demonstrated in field and laboratory studies. Inoculation of logs with P. gigantea resulted in successful colonization of the entire log, with up to 100% of the sapwood colonized after 8 weeks in the field. Treated logs removed up to 71% of the resin extractives present within logs. Inoculation of logs with P. gigantea also enhanced the removal of bark from the cambial layer. Evaluation of refined wood fibers from treated logs revealed an increase in Simons' stain, showing orange-yellow staining of the whole fiber. This suggests that P. gigantea causes extensive changes in cell wall porosity and may improve paper strength properties. Inoculation of logs with P. gigantea also resulted in the complete inhibition of blue stain fungi from cut logs, while non-inoculated logs had up to 53% of the sapwood colonized by blue stain fungi and 31% of the sapwood stained. Detailed investigations of the mechanisms used by P. gigantea in biocontrol of blue stain fungi were evaluated. As colonization by P. gigantea increased, colonization by blue stain fungi and staining of the sapwood decreased. Observations of fungal interactions between P. gigantea and O. piliferum showed hyphae of P. gigantea coiling around O. piliferum and directly penetrating cell walls of the fungus. As time progressed, blue stain hyphae began to collapse and lyse causing a release in cellular contents that most likely included melanin. Results suggested that P. gigantea controls blue stain fungi through resource competition and mycoparasitism. Results from biomechanical pulping studies demonstrated the ability of P. gigantea to enhance refiner mechanical pulping of loblolly and red pine logs. Mechanical refining of wood from logs inoculated with P. gigantea consumed up to 27% less energy than mechanical refining of wood from non-inoculated logs. These results demonstrated that P. gigantea is well suited for biological processing resulting in substantial benefits for the pulp and paper industry.