Eucalyptus Cell Wall Architecture: Clues for Lignocellulosic Biomass Deconstruction

The architecture, composition, and chemical properties of wood cell walls have a direct influence on the process that occurs prior to fermentation in second-generation biofuel production. The understanding of the construction patterns of cell wall types is the key to the new era of second-generation biofuels. Eucalyptus species are great candidates for this purpose since these species are among the fastest growing hardwood trees in the world and they have been improved for biomass production. We applied the glycome profiling and other combined techniques to study xylem cell walls of three economically important species (Eucalyptus globulus, Eucalyptus grandis, and Eucalyptus urophylla). Glycome profiling analyses revealed that species differ in the same key aspects of cell wall polymer linkages, with E. globulus and E. urophylla presenting contrasting phenotypes, and E. grandis with intermediate characteristics. E. urophylla is known for high recalcitrance, that is probably determined by the strong associations between lignin and cell wall polymers, and also lignin content. On the other hand, E. globulus cell wall polymers are loosely linked, so its cell wall can be easily deconstructed. We have shown in this work that the composition of cell walls differs in quantity and quality among the Eucalyptus species and such variations in composition influence the process of lignocellulosic feedstock assessment. However, the greatest influence relies on the amount and type of associations between cell wall polymers. A high yield of cellulose, from any biomass source, directly depends on the cell wall architecture.