Co-Utilization of Glucose and Xylose for Enhanced Lignocellulosic Ethanol Production with Reverse Membrane Bioreactors

Abstract

Integrated permeate channel (IPC) flat sheet membranes were examined for use as a reverse membrane bioreactor (rMBR) for lignocellulosic ethanol production. The fermenting organism, Saccharomyces cerevisiae (T0936), a genetically-modified strain with the ability to ferment xylose, was used inside the rMBR. The rMBR was evaluated for simultaneous glucose and xylose utilization as well as in situ detoxification of furfural and hydroxylmethyl furfural (HMF). The synthetic medium was investigated, after which the pretreated wheat straw was used as a xylose-rich lignocellulosic substrate. The IPC membrane panels were successfully used as the rMBR during the batch fermentations, which lasted for up to eight days without fouling. With the rMBR, complete glucose and xylose utilization, resulting in 86% of the theoretical ethanol yield, was observed with the synthetic medium. Its application with the pretreated wheat straw resulted in complete glucose consumption and 87% xylose utilization; a final ethanol concentration of 30.3 g/L was obtained, which corresponds to 83% of the theoretical yield. Moreover, complete in situ detoxification of furfural and HMF was obtained within 36 h and 60 h, respectively, with the rMBR. The use of the rMBR is a promising technology for large-scale lignocellulosic ethanol production, since it facilitates the co-utilization of glucose and xylose; moreover, the technology would also allow the reuse of the yeast for several batches.

Enzymatic Conversion of Sugar Beet Pulp: A Comparison of Simultaneous Saccharification and Fermentation and Separate Hydrolysis and Fermentation for Lactic Acid Production

“…Therefore, we considered the SSF mode with lower enzyme doses. In this process, enzymes work with fermenting microorganisms to convert the released components into bioproducts (32). Regarding the activities of enzymes correlated with carbohydrate catabolism, -mannosidase, and -fucosidase were not detected, while -andgalactosidase, -and -glucosidase, -glucuronidase activities were found in all tested strains.…”

Lignocellulosic bioethanol production: prospects of emerging membrane technologies to improve the process – a critical review

“…In this study, fermentation was carried out in 20 l pilot plant bioreactor system integrated with firststage MF unit and second-stage NF unit. The concept of reverse MBR (rMBR) where cells are immobilized between immersed membrane layers and separated from actual substrate solution is recently introduced by Ishola et al (2015b). Cells are encapsulated between synthetic membrane layers in the form of compact multilayer membrane column or IPC flat sheet membrane (Doyen et al 2010).…”

“…Cells are encapsulated between synthetic membrane layers in the form of compact multilayer membrane column or IPC flat sheet membrane (Doyen et al 2010). Such kind of advanced IPC rMBR configuration was used for bioethanol production from wheat straw hydrolyzate using recombinant yeast (Ishola et al 2015b). Improved simultaneous utilization of xylose and glucose with in situ detoxification of inhibitory components was facilitated by such novel configuration.…”

Enhancement of Simultaneous Xylose and Glucose Utilization by Regulating ZWF1 and PGI1 in Saccharomyces Cerevisiae

“…Previous research has revealed that the increase in the concentrations of glucose decreased xylose consumption and that hexose transporter overexpression Hxt7 partially relieved the inhibitory effects of increasing glucose concentration [46]. Ishola et al [47,48] reported that glucose concentration affected xylose uptake in SSFF or in reverse membrane bioreactors. In recombinant flocculent S. cerevisiae the best ratio of glucose/xylose for the highest xylose consumption rate was 2:3 among different ratios [49].…”