Biological Modification of Cellulose
- Jody Jellison
- Caitlin Howell
- Anne Christine Hastrup, University of Copenhagen, Denmark & LAAST, UMaine
- Barry Goodell, UMaine
- Amanda Turcotte, undergraduate UMaine
- Steve Carr, undergraduate UMaine
- Stewart Gramlich, undergraduate UMaine
Wood is a very complex material. In order to effectively and sustainably use wood for chemicals and fuels, we must first be able to break it down efficiently. Wood decay fungi are some of only a few types of organisms on the planet that have evolved ways of breaking apart wood components, yet the mechanisms they use are still not completely understood. Our project involves examining the ways in which wood decay fungi break down wood. In particular, we examine the effects these fungi have on specific wood components such as crystalline cellulose, and we attempt to duplicate these effects with chemicals and enzymes.
The destruction of wood by decay fungi has been studied intensely for many years due to its importance in both preservation of in-service wood and nutrient cycling in forests and other ecosystems. These organisms also present a potential method of modifying or deconstructing wood for use in bioproducts and bioenergy.
However, there remain many unanswered questions in this field, due at least in part to the difficulties associated with collecting and interpreting data about the biological processes of an organism growing in a material as complex as wood. The method of examining crystalline cellulose by x-ray diffraction presents a non-destructive and relatively unexplored way to observe yet another facet of the breakdown of wood by decay fungi. The ability to break apart these structures may also be used as an indicator of the effectiveness of these organisms, and ultimately an assessment of suitability for bioprocessing purposes, as crystallite cellulose modification first requires degrading or modifying more easily accessible components of the wood cell wall such as lignin, hemicelluloses and the amorphous portions of the cellulose microfibrils.
The deconstruction of crystalline cellulose is also the rate-limiting step in the conversion of biomass to ethanol, making an understanding of more efficient methods potentially interesting to industry.
What’s New on this Project?
Recent results show distinct patterns in the process of crystalline cellulose break down by four different types of brown rot fungi. Ongoing tests are examining if this pattern holds for other species of brown rot fungi as well as a few select white rot fungi.
Experiments are also being conducted to duplicate fungal deconstruction of crystalline cellulose using only chemicals. Early data suggest that the addition of Fenton’s reagents to wood flour over time can significantly increase the size of cellulose nanocrystals while decreasing the overall wood crystallinity. Results have also indicated that the presence of oxalic acid, a strong organic acid secreted by wood decay fungi into their environment, may also play a roll.