Solvent Selection for Lignin Value Prior to Pulping

Solvent selection guides are crucial in chemical process design and development. Lignin from lignocellulosic biomass is a potentially attractive feedstock for sustainable chemical feedstocks. One approach would use a solvent to recover lignin prior to the traditional pulping process to make cellulose fibers: lignin value prior to pulping (LVPP). A solvent selection methodology for LVPP is presented herein that may be expanded for any proposed solvent for this process. Four screening categories are elucidated, providing metrics for 30 solvents across multiple molecular functional groups. Through performance, hazards and environment, cost and availability, and process-economics screens, the initial list of solvents is reduced to two top-tier candidates, 1,6 hexamethylenediamine and diethanolamine. 1-Methylpiperazine also emerged as a potential candidate. This solvent-selection methodology streamlines experimentation and provides promising candidates for LVPP. In addition to creating a tailored solvent selection guide, valuable biomass pretreatment data that may be utilized in different renewable applications are also presented.

Schizosaccharomyces pombe as an Efficient Yeast to Convert Sugarcane Bagasse Pretreated with Ionic Liquids in Ethanol

Pretreatment of lignocellulosic biomass with ionic liquids (ILs) has been extensively studied, being regarded as one of the most promising methods for obtaining fermentable sugars. In this research, it was investigated the production of ethanol from sugars released from sugarcane bagasse pretreated with the ionic liquids [C₄mim][OAc] and [C₂mim][OAc], hydrolysed with Penicillium echinulatum enzymes and using Saccharomyces cerevisiae and Schizosaccharomyces pombe. Yields of about 43 and 56% of ethanol were observed for S. cerevisiae and biomass pretreated with [C₂mim][OAc] and [C₄mim][OAc], respectively. S. pombe yielded 52 and 78% ethanol for [C₂mim][OAc] and [C₄mim][OAc], respectively. These results indicate that S. pombe showed best performance for alcoholic fermentation from sugars released from pretreated biomass by ILs.

High-performance of Agaricus blazei fungus for the biological pretreatment of elephant grass

Biological pre-treatment seems to be promising being an eco-friendly process, with no inhibitor generated during the process. The potential for elephant grass pre-treatment with white degradation fungi Pleurotus ostreatus, Agaricus blazei, Lentinula edodes, Pleurotus citrinopileatus, and Pleurotus djamor, in isolated or mixed cultures of these strains, was evaluated. The highest activities of enzymes involved in the degradation of lignocellulosic biomass (laccases, endoglucanases, xylanases, and β-glucosidases) were observed for A. blazei, L. edodes and the combination of P. ostreatus and A. blazei. In the enzymatic hydrolysis, there was greater release of reducing sugars in the pre-treated elephant grass samples by A. blazei during 10 days (338.91 ± 7.39 mg g^-1 of biomass). For this sample, higher lignin reductions, 24.81 and 57.45%, after 15 and 35 days of incubation, respectively, were also verified. These data indicate the potential of macromycetes such as A. blazei to perform biological pre-treatments. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:42-50, 2018.

Co-fermentation using Recombinant Saccharomyces cerevisiae Yeast Strains Hyper-secreting Different Cellulases for the Production of Cellulosic Bioethanol

To realize the economical production of ethanol and other bio-based chemicals from lignocellulosic biomass by consolidated bioprocessing (CBP), various cellulases from different sources were tested to improve the level of cellulase secretion in the yeast Saccharomyces cerevisiae by screening an optimal translational fusion partner (TFP) as both a secretion signal and fusion partner. Among them, four indispensable cellulases for cellulose hydrolysis, including Chaetomium thermophilum cellobiohydrolase (CtCBH1), Chrysosporium lucknowense cellobiohydrolase (ClCBH2), Trichoderma reesei endoglucanase (TrEGL2), and Saccharomycopsis fibuligera β-glucosidase (SfBGL1), were identified to be highly secreted in active form in yeast. Despite variability in the enzyme levels produced, each recombinant yeast could secrete approximately 0.6–2.0 g/L of cellulases into the fermentation broth. The synergistic effect of the mixed culture of the four strains expressing the essential cellulases with the insoluble substrate Avicel and several types of cellulosic biomass was demonstrated to be effective. Co-fermentation of these yeast strains produced approximately 14 g/L ethanol from the pre-treated rice straw containing 35 g/L glucan with 3-fold higher productivity than that of wild type yeast using a reduced amount of commercial cellulases. This process will contribute to the cost-effective production of bioenergy such as bioethanol and biochemicals from cellulosic biomass.