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

Mofoluwake Ishola,Mohammad Taherzadeh,Päivi Ylitervo

doi:10.3390/membranes5040844

Mofoluwake Ishola, Mohammad Taherzadeh + Show 1 more

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https://doi.org/10.3390/membranes5040844

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Journal: Membranes	Publication Date: Dec 3, 2015
Citations: 43	License type: CC BY 4.0

Affiliation: University of Borås, Lagos State University

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.

Highlights

Ethanol production from lignocellulosic materials, such as woody biomass, forest, and agricultural residues, has the potential of reducing society’s dependence on fossil fuels [1–3]
This study investigated the use of integrated permeate channels (IPC) membranes in a reverse manner for lignocellulosic ethanol production, a technology referred to as reverse membrane reactor (rMBR)
The agglomeration of cells will facilitate the simultaneous utilization of glucose and xylose as well as in situ detoxification of the bioconvertible inhibitors

Summary

Introduction

Ethanol production from lignocellulosic materials, such as woody biomass, forest, and agricultural residues, has the potential of reducing society’s dependence on fossil fuels [1–3]. Lignocellulosic materials consist of three main structural components: cellulose, hemicellulose, and lignin [4–6]. The hemicellulose fraction of hardwoods and agricultural residues, e.g., wheat straw, is dominated by xylose; xylose utilization is essential for the successful fermentation of all the sugars into ethanol. The wild-type of yeast, Saccharomyces cerevisiae, which is commonly used for the fermentation of sugar to ethanol, cannot utilize xylose. The use of genetically-engineered S. cerevisiae for xylose uptake for the fermentation of xylose-rich biomass for ethanol production is one of the options that have been widely investigated [7–9]. The genetically-modified strain prefers glucose in a mixture of glucose and xylose, leading to the sequential utilization of sugars and, incomplete sugar utilization [10–12]

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