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In a previous study by the authors, it was found that benzene-ethanol extraction (BAE) could remove some of the lignin fragments from pretreated bamboo substrate and therefore cause a decrease in the lignin content of the substrate. In the present study, lignin was isolated by dioxane extraction of enzyme hydrolysis of ball-milled substrate (CEL method), and the effects of BAE on lignin molecular weight (MW) were determined. Results indicated that hydrothermal pretreatment could facilitate lignin isolation substantially when CEL method was used. Lignin fragments with low MW were more sensitive to BAE, and therefore, evident increase in both weight average molecular weight (Mw) and number average molecular weight (Mn) was observed; especially, the increase rate of Mn was more than 2.5 times of Mw when degradation prevailed. However, subtle changes were found in Fourier transform infrared spectroscopy and carbon-13 nuclear magnetic resonance spectra between the lignin samples with and without BAE; the solubility of lignin in benzene-ethanol solution was more dependent on the MW level than on the functional groups in lignin structure. [ABSTRACT FROM AUTHOR]

Continuous production of acetone, n-butanol, and ethanol (ABE) was carried out using immobilized cells of Clostridium acetobutylicum DSM 792 using glucose and sugar mixture as a substrate. Among various lignocellulosic materials screened as a support matrix, coconut fibers and wood pulp fibers were found to be promising in batch experiments. With a motive of promoting wood-based bio-refinery concept, wood pulp was used as a cell holding material. Glucose and sugar mixture (glucose, mannose, galactose, arabinose, and xylose) comparable to lignocellulose hydrolysate was used as a substrate for continuous production of ABE. We report the best solvent productivity among wild-type strains using column reactor. The maximum total solvent concentration of 14.32 g L was obtained at a dilution rate of 0.22 h with glucose as a substrate compared to 12.64 g L at 0.5 h dilution rate with sugar mixture. The maximum solvent productivity (13.66 g L h) was obtained at a dilution rate of 1.9 h with glucose as a substrate whereas solvent productivity (12.14 g L h) was obtained at a dilution rate of 1.5 h with sugar mixture. The immobilized column reactor with wood pulp can become an efficient technology to be integrated with existing pulp mills to convert them into wood-based bio-refineries. [ABSTRACT FROM AUTHOR]