Biological and chemical pretreatment of grasses to overcome lignin’s recalcitrance improvingcarbohydrate degradability
2018
Mouthier, Thibaut M.B.
The research described in this PhD-thesis aimed to identify new routes to release monosaccharides from hard-to-convert feedstocks by a detailed structural analysis of the recalcitrant carbohydrate and lignin released from grass feedstocks mildly treated with 1) intrinsic chemical catalysts (acetic acid and ammonium); 2) novel enzymes and; 3) combination of both.Loosening of the architecture of cell walls is known to enhance accessibility to enzymes. However, the residual lignin structures are not fully understood and will vary depending on the plant source and the targeted product (i.e. conversion to biochemicals, opening the structures for compost). Hence, this research focused on the variability and the lignin recalcitrant structures of 2 main grasses (corn stover, wheat straw) and how they can be affected by a biological process (rumen digestion or composting process), by an ammonia pretreatment, and by an acetic acid (enzymatically released or added to the treatment) or sulfuric acid pretreatment. The effects and the modifications of lignin were evaluated for to their influence on further enzymatic degradation of polysaccharides. Furthermore, the presence and the use of intrinsic catalysts within the biomass or within the process was investigated to increase the severity of pretreatment and its following degradability.
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