Ethanol production from lignocellulosic hydrolysates using engineered Saccharomyces cerevisiae harboring xylose isomerase-based pathway

Ko, Ja Kyong; Um, Youngsoon; Woo, Han Min; Kim, Kyoung Heon; Lee, Sun Mi

doi:10.1016/j.biortech.2016.02.124

Cited by 101 publications

(54 citation statements)

References 30 publications

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“…In general, multiple modifications have been used, including the rational establishment of a xylose metabolic pathway and non-rational adaptive evolution to improve xylose metabolic capacity and inhibitor tolerance (Kim et al 2013; Ko et al 2016; Kuyper et al 2005a; Peng et al 2012; Van Vleet and Jeffries 2009). Moreover, using robust yeast strains as chassis cells has also proved to be an effective strategy (Demeke et al 2013; Diao et al 2013; Li et al 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Its cost-effective production process depends on the complete and rapid utilization of all the sugars in the hydrolysates derived from lignocellulosic raw materials (Ko et al 2016; Moysés et al 2016; Peng et al 2012; Zhou et al 2012). The budding yeast Saccharomyces cerevisiae is a prominent microorganism that has traditionally been used in industrial bioethanol production because of its numerous inherent advantages (Demeke et al 2013).…”

Section: Introductionmentioning

confidence: 99%

“…First, natural S. cerevisiae cannot effectively metabolize pentose sugars, particularly d -xylose, the second most abundant sugar in lignocellulosic materials because it lacks an effective initial metabolic pathway (Hahn-Hägerdal et al 2007; van Maris et al 2006). Second, the individual and synergistic negative interactions derived from the numerous inhibitory compounds that are formed during the pretreatment process and the hydrolytic release of sugars exert serious negative effects on the fermentation performance of S. cerevisiae (Ko et al 2016; Palmqvist and Hahn-Hägerdal 2000). Therefore, for the economically viable and sustainable production of lignocellulosic bioethanol, it is necessary to confer the capacity to co-ferment glucose and xylose on an S. cerevisiae strain and to enhance its resistance to harsh production environments (Demeke et al 2013; Li et al 2015; Sharma et al 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, little attention is given to the synchronous fermentation of both sugars. In fact, the obvious hysteresis of xylose fermentation compared with glucose has been extensively observed, manifestations of which exhibit a delay not only with respect to initial xylose utilization and the xylose consumption rate but also the time to maximum ethanol production; in other words, the ethanol production value increases incrementally after glucose exhaustion (Ko et al 2016; Peng et al 2012; Reider Apel et al 2016; Sharma et al 2016). Therefore, a yeast strain that co-ferments xylose and glucose with the same consumption rate (i.e., synchronously) would be ideal.…”

Section: Introductionmentioning

confidence: 99%

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Engineering a wild-type diploid Saccharomyces cerevisiae strain for second-generation bioethanol production

Shen

et al. 2016

Bioresour. Bioprocess.

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BackgroundThe cost-effective production of second-generation bioethanol, which is made from lignocellulosic materials, has to face the following two problems: co-fermenting xylose with glucose and enhancing the strain’s tolerance to lignocellulosic inhibitors. Based on our previous study, the wild-type diploid Saccharomyces cerevisiae strain BSIF with robustness and good xylose metabolism genetic background was used as a chassis for constructing efficient xylose-fermenting industrial strains. The performance of the resulting strains in the fermentation of media with sugars and hydrolysates was investigated.ResultsThe following two novel heterologous genes were integrated into the genome of the chassis cell: the mutant MGT05196 N360F, which encodes a xylose-specific, glucose-insensitive transporter and is derived from the Meyerozyma guilliermondii transporter gene MGT05196, and Ru-xylA (where Ru represents the rumen), which encodes a xylose isomerase (XI) with higher activity in S. cerevisiae. Additionally, endogenous modifications were also performed, including the overproduction of the xylulokinase Xks1p and the non-oxidative PPP (pentose phosphate pathway), and the inactivation of the aldose reductase Gre3p and the alkaline phosphatase Pho13p. These rationally designed genetic modifications, combined with alternating adaptive evolutions in xylose and SECS liquor (the leach liquor of steam-exploding corn stover), resulted in a final strain, LF1, with excellent xylose fermentation and enhanced inhibitor resistance. The specific xylose consumption rate of LF1 reached as high as 1.089 g g−1 h−1 with xylose as the sole carbon source. Moreover, its highly synchronized utilization of xylose and glucose was particularly significant; 77.6% of xylose was consumed along with glucose within 12 h, and the ethanol yield was 0.475 g g−1, which is more than 93% of the theoretical yield. Additionally, LF1 performed well in fermentations with two different lignocellulosic hydrolysates.ConclusionThe strain LF1 co-ferments glucose and xylose efficiently and synchronously. This result highlights the great potential of LF1 for the practical production of second-generation bioethanol.Electronic supplementary materialThe online version of this article (doi:10.1186/s40643-016-0126-4) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Engineering a wild-type diploid Saccharomyces cerevisiae strain for second-generation bioethanol production

Shen

et al. 2016

Bioresour. Bioprocess.

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“…Methods for obtaining microorganisms capable of simultaneous consumption of glucose and xylose include mutagenesis and the introduction a heterologous metabolic pathway for xylose utilization into well-known conventional strains such as S. cerevisiae (30,80). Cellulase-encoding genes may also be introduced into specific species during recombination (81).…”

Section: Recombinant Fermentative Microbesmentioning

confidence: 99%

Review of Second-Generation Bioethanol Production from Residual Biomass

Robak

Balcerek

2018

Food Technol. Biotechnol.

467

183

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SummaryIn the context of climate change and the depletion of fossil fuels, there is a great need for alternatives to petroleum in the transport sector. This review provides an overview of the production of second-generation bioethanol, which is distinguished from first-generation and subsequent generations of biofuels by its use of lignocellulosic biomass as raw material. The structural components of the lignocellulosic biomass such as cellulose, hemicellulose and lignin, are presented along with technological unit steps including pre-treatment, enzymatic hydrolysis, fermentation distillation and dehydration. The purpose of the pre-treatment step is to increase the surface area of carbohydrate available for enzymatic saccharification, while minimizing inhibitors. Performing the enzymatic hydrolysis releases fermentable sugars, which are converted by microbial catalysts into ethanol. The hydrolysates obtained after pre-treatment and enzymatic hydrolysis contain a wide spectrum of sugars, predominantly glucose and xylose.Genetically engineered microorganisms are therefore needed to carry out co-fermentation. The excess of harmful inhibitors in the hydrolysate, such as weak organic acids, furan derivatives and phenol components, can be removed by detoxification before fermentation. Effective saccharification further requires using co-acting exogenous hemicellulases and cellulolytic www.ftb.com.hrPlease note that this is an unedited version of the manuscript that has been accepted for publication. This version will undergo copyediting and typesetting before its final form for publication. We are providing this version as a service to our readers. The published version will differ from this one as a result of linguistic and technical corrections and layout editing.enzymes. Conventional species of distillers' yeast are unable to ferment pentoses into ethanol, and only a very few natural microorganisms, including yeast species like Candida shehatae, Pichia stipites, Scheffersomyces and Pachysolen tannophilus, metabolize xylose to ethanol.Enzymatic hydrolysis and fermentation can be performed in a number of ways, by separate saccharification and fermentation, simultaneous saccharification and fermentation or consolidated bioprocessing. Pentose-fermenting microorganisms can be obtained through genetic engineering, by introducing xylose-encoding genes into metabolism of a selected microorganism to optimize its use of xylose accumulated in the hydrolysate.

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