No abstract

α-Etherification in diol pretreatment quenched lignin intermediate and produced a reactive lignin with hydroxyl tails. Hydroxyl tails increased lignin solubilization without cleavage of β-O-4 ether linkages.

Lignocellulosic biomass is a promising feedstock for sustainable production of non‐food building‐block sugars. This bioconversion process is preferentially carried out through the whole slurry enzymatic saccharification of the pre‐treated lignocellulosic substrates. However, dissolved lignin, residual lignin, and lignin‐derived phenolic molecules in the pre‐treated biomass slurry can all trigger the decrease in activity and stability of cellulases, as well as the unfavorable enzyme recyclability. The hydrolyzing efficiencies can be considerably hindered by the lignin‐induced non‐productive binding of cellulases through various mechanisms. Three major non‐covalent forces, i.e., hydrophobic, electrostatic, and hydrogen bonds interactions, can occur between the amino acid residues in cellulases and the functional groups in lignin. Various strategies such as enzyme engineering, substrate modification, additive blocking have been intensively developed to minimize the cellulase‐lignin interactions. To investigate the impacts and benefits of different mechanisms and processes, this paper provides a systematic overview of the current opinions about the non‐productive binding of cellulase to lignin. Through better understanding of their interactions it is our hope that the enzyme binding groups in lignin could be properly quenched by using new pre‐treatment methods and/or biochemical processing strategies to increase the efficiency of cellulose bioconversion. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd

Mountain pine beetle killed Lodgepole pine (Pinus contorta Douglas ex Loudon) wood chips were pretreated using an acidic sulfite solution of approximately pH = 2.0 at a liquor to wood ratio of 3 and sodium bisulfite loading of 8 wt % on wood. The combined hydrolysis factor (CHF), formulated from reaction kinetics, was used to design a scale-up pretreatment on 2000 g wood chips at a relatively low temperature of 165 °C that reduced furan formation and facilitated high solids saccharification and fermentation. The pretreated solids and liquor were disk milled together to result in a biomass whole slurry of 25% total solids. The whole biomass slurry was directly used to conduct simultaneous enzymatic saccharification and combined fermentation (SSCombF) using a commercial cellulase and Saccharomyces cerevisiae YRH400 without detoxification. A terminal ethanol titer of 47.1 g L–1 with a yield of 306 L (tonne wood)−1, or 72.0% theoretical, was achieved when SSCombF was conducted at an unwashed solids loading of 18%. The lignosulfonate (LS) from SPORL was highly sulfonated and showed better dispersibility than a high purity commercial softwood LS, and therefore has potential as a directly marketable coproduct.