http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Compounds inhibiting the bioconversion of hydrothermally pretreated lignocellulose
Ko, Ja Kyong,Um, Youngsoon,Park, Yong-Cheol,Seo, Jin-Ho,Kim, Kyoung Heon Springer-Verlag 2015 Applied microbiology and biotechnology Vol.99 No.10
<P>Hydrothermal pretreatment using liquid hot water, steam explosion, or dilute acids enhances the enzymatic digestibility of cellulose by altering the chemical and/or physical structures of lignocellulosic biomass. However, compounds that inhibit both enzymes and microbial activity, including lignin-derived phenolics, soluble sugars, furan aldehydes, and weak acids, are also generated during pretreatment. Insoluble lignin, which predominantly remains within the pretreated solids, also acts as a significant inhibitor of cellulases during hydrolysis of cellulose. Exposed lignin, which is modified to be more recalcitrant to enzymes during pretreatment, adsorbs cellulase nonproductively and reduces the availability of active cellulase for hydrolysis of cellulose. Similarly, lignin-derived phenolics inhibit or deactivate cellulase and β-glucosidase via irreversible binding or precipitation. Meanwhile, the performance of fermenting microorganisms is negatively affected by phenolics, sugar degradation products, and weak acids. This review describes the current knowledge regarding the contributions of inhibitors present in whole pretreatment slurries to the enzymatic hydrolysis of cellulose and fermentation. Furthermore, we discuss various biological strategies to mitigate the effects of these inhibitors on enzymatic and microbial activity to improve the lignocellulose-to-biofuel process robustness. While the inhibitory effect of lignin on enzymes can be relieved through the use of lignin blockers and by genetically engineering the structure of lignin or of cellulase itself, soluble inhibitors, including phenolics, furan aldehydes, and weak acids, can be detoxified by microorganisms or laccase.</P>
Ko, Ja Kyong,Jung, Je Hyeong,Altpeter, Fredy,Kannan, Baskaran,Kim, Ha Eun,Kim, Kyoung Heon,Alper, Hal S.,Um, Youngsoon,Lee, Sun-Mi Elsevier 2018 Bioresource technology Vol.256 No.-
<P><B>Abstract</B></P> <P>The recalcitrant structure of lignocellulosic biomass is a major barrier in efficient biomass-to-ethanol bioconversion processes. The combination of feedstock engineering via modification in the lignin synthesis pathway of sugarcane and co-fermentation of xylose and glucose with a recombinant xylose utilizing yeast strain produced 148% more ethanol compared to that of the wild type biomass and control strain. The lignin reduced biomass led to a substantially increased release of fermentable sugars (glucose and xylose). The engineered yeast strain efficiently co-utilized glucose and xylose for fermentation, elevating ethanol yields. In this study, it was experimentally demonstrated that the combined efforts of engineering both feedstock and microorganisms largely enhances the bioconversion of lignocellulosic feedstock to bioethanol. This strategy will significantly improve the economic feasibility of lignocellulosic biofuels production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The use of lignin-modified biomass with engineered yeast improved ethanol production. </LI> <LI> Ethanol yields were elevated by 148%. </LI> <LI> This strategy maximizes the overall efficiency for lignocellulosic biofuel production. </LI> </UL> </P>
Ko, Ja Kyong,Lee, Sun-Mi Elsevier 2018 Current opinion in biotechnology Vol.50 No.-
<P>Cellulosic fuels are expected to have great potential industrial applications in the near future, but they still face technical challenges to become cost-competitive fuels, thus presenting many opportunities for improvement. The economical production of viable biofuels requires metabolic engineering of microbial platforms to convert cellulosic biomass into biofuels with high titers and yields. Fortunately, integrating traditional and novel engineering strategies with advanced engineering toolboxes has allowed the development of more robust microbial platforms, thus expanding substrate ranges. This review highlights recent trends in the metabolic engineering of microbial platforms, such as the industrial yeasts <I>Saccharomyces cerevisiae</I> and <I>Yarrowia lipolytica</I>, for the production of renewable fuels.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Metabolic engineering improves microbial production of cellulosic fuels. </LI> <LI> We highlight a paradigm shift in engineering of ethanol producer, <I>S. cerevisiae</I>. </LI> <LI> Strain engineering focuses on improving carbon utilization and stress tolerance. </LI> <LI> An oleaginous yeast, <I>Y. lipolytica</I>, is an emerging cellulosic biodiesel producer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>