Challenges and opportunities in mimicking non-enzymatic brown-rot decay mechanisms for pretreatment of Norway spruce
- 206 Downloads
The recalcitrance bottleneck of lignocellulosic materials presents a major challenge for biorefineries, including second-generation biofuel production. Because of their abundance in the northern hemisphere, softwoods, such as Norway spruce, are of major interest as a potential feedstock for biorefineries. In nature, softwoods are primarily degraded by basidiomycetous fungi causing brown rot. These fungi employ a non-enzymatic oxidative system to depolymerize wood cell wall components prior to depolymerization by a limited set of hydrolytic and oxidative enzymes. Here, it is shown that Norway spruce pretreated with two species of brown-rot fungi yielded more than 250% increase in glucose release when treated with a commercial enzyme cocktail and that there is a good correlation between mass loss and the degree of digestibility. A series of experiments was performed aimed at mimicking the brown-rot pretreatment, using a modified version of the Fenton reaction. A small increase in digestibility after pretreatment was shown where the aim was to generate reactive oxygen species within the wood cell wall matrix. Further experiments were performed to assess the possibility of performing pretreatment and saccharification in a single system, and the results indicated the need for a complete separation of oxidative pretreatment and saccharification. A more severe pretreatment was also completed, which interestingly did not yield a more digestible material. It was concluded that a biomimicking approach to pretreatment of softwoods using brown-rot fungal mechanisms is possible, but that there are additional factors of the system that need to be known and optimized before serious advances can be made to compete with already existing pretreatment methods.
This work was financed by the Research Council of Norway 243663/E50 BioMim and the Norwegian Institute for Bioeconomy Research.
- Cowling EB (1961) Comparative biochemistry of the decay of sweetgum sapwood by white-rot and brown-rot fungi, vol 1258. US Department of Agriculture, WashingtonGoogle Scholar
- Curling SF, Clausen CA, Winandy JE (2002) Relationships between mechanical properties, weight loss, and chemical composition of wood during incipient brown-rot decay. For Prod J 52:34Google Scholar
- Flournoy DS, Kirk TK, Highley T (1991) Wood decay by brown-rot fungi: changes in pore structure and cell wall volume Holzforschung. Int J Biol Chem Phys Technol Wood 45:383–388Google Scholar
- Goodell B, Nakamura M, Jellison J (2014) The chelator mediated Fenton system in the brown rot fungi: details of the mechanism, and reasons why it has been ineffective as a biomimetic treatment in some biomass applications: a review. In: Jermer J (ed) Proceedings IRG/WP, St. George, Utah. USA, 2014. IRG/WP, p 8Google Scholar
- Noriega OAU (2016) Sistemas oxidativos e biomiméticos aplicados à hidrólise enzimática de materiais lignocelulósicos. (Oxidative-biomimetic systems applied to enzymatic hydrolysis of lignocellulosic materials). Ph.D. University of São Paulo. Lorena Campus, BrazilGoogle Scholar
- Ogner G et al (1999) The chemical analysis program of the Norwegian Forest Research Institute 2000. Internal reportGoogle Scholar
- Orejuela LM (2017) Lignocellulose deconstruction using glyceline and a chelator-mediated Fenton system. Ph.D., Virginia Polytechnic Institute and State UniversityGoogle Scholar
- Paszczynski A, Crawford R, Funk D, Goodell B (1999) De Novo synthesis of 4,5-dimethoxycatechol and 2,5-dimethoxyhydroquinone by the brown rot fungus Gloeophyllum trabeum. Appl Environ Microbiol 65:674–679Google Scholar
- Sluiter A, Hames B, Ruiz R, Scarlata C, Sluiter J, Templeton D, Crocker D (2008) Determination of structural carbohydrates and lignin in biomass. Lab Anal Proced 1617:1–16Google Scholar