Simultaneous fermentation of glucose and xylose at elevated temperatures co-produces ethanol and xylitol through overexpression of a xylose-specific transporter in engineered Kluyveromyces marxianus

Zhang, Biao; Zhang, Jia; Wang, Dongmei; Han, Ruixiang; Ding, Rui; Gao, Xiaolian; Sun, Lianhong; Hong, Jiong

doi:10.1016/j.biortech.2016.05.068

Cited by 56 publications

(32 citation statements)

References 33 publications

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“…A number of reports support the findings that K. marxianus has limited capacity to uptake C5 sugars in comparison to its ability to metabolize glucose and other C6 sugars . Genetic engineering of xylose metabolism aimed at eliminating a redox imbalance during xylose catabolism have been demonstrated and result in improved xylose uptake and K. marxianus growth .…”

Section: Resultsmentioning

confidence: 86%

High throughput, colorimetric screening of microbial ester biosynthesis reveals high ethyl acetate production from Kluyveromyces marxianus on C5, C6, and C12 carbon sources

Löbs

Lin

Cook

et al. 2016

Biotechnology Journal

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Advances in genome and metabolic pathway engineering have enabled large combinatorial libraries of mutant microbial hosts for chemical biosynthesis. Despite these advances, strain development is often limited by the lack of high throughput functional assays for effective library screening. Recent synthetic biology efforts have engineered microbes that synthesize acetyl and acyl esters and many yeasts naturally produce esters to significant titers. Short and medium chain volatile esters have value as fragrance and flavor compounds, while long chain acyl esters are potential replacements for diesel fuel. Here, we developed a biotechnology method for the rapid screening of microbial ester biosynthesis. Using a colorimetric reaction scheme, esters extracted from fermentation broth were quantitatively converted to a ferric hydroxamate complex with strong absorbance at 520 nm. The assay was validated for ethyl acetate, ethyl butyrate, isoamyl acetate, ethyl hexanoate, and ethyl octanoate, and achieved a z-factor of 0.77. Screening of ethyl acetate production from a combinatorial library of four Kluyveromyces marxianus strains on seven carbon sources revealed ethyl acetate biosynthesis from C5, C6, and C12 sugars. This newly adapted method rapidly identified novel properties of K. marxianus metabolism and promises to advance high throughput microbial strain engineering for ester biosynthesis.

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Section: Resultsmentioning

confidence: 86%

High throughput, colorimetric screening of microbial ester biosynthesis reveals high ethyl acetate production from Kluyveromyces marxianus on C5, C6, and C12 carbon sources

Löbs

Lin

Cook

et al. 2016

Biotechnology Journal

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“…These transporters are proteins to be studied in relation to their potential of transport sugars released from vegetal biomass, such as xylose, cellobiose, and arabinose and can be used to the genetic engineering of industrial strain applied in different industrial fermentations [65, 66]. Recently, Sloothaak et al [67] applied a pipeline to identify putative xylose transporters to the in silico deduced proteomes of T. reesei and A. niger .…”

Section: Resultsmentioning

confidence: 99%

Comparative transcriptome analysis reveals different strategies for degradation of steam-exploded sugarcane bagasse by Aspergillus niger and Trichoderma reesei

et al. 2017

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BackgroundSecond generation (2G) ethanol is produced by breaking down lignocellulosic biomass into fermentable sugars. In Brazil, sugarcane bagasse has been proposed as the lignocellulosic residue for this biofuel production. The enzymatic cocktails for the degradation of biomass-derived polysaccharides are mostly produced by fungi, such as Aspergillus niger and Trichoderma reesei. However, it is not yet fully understood how these microorganisms degrade plant biomass. In order to identify transcriptomic changes during steam-exploded bagasse (SEB) breakdown, we conducted a RNA-seq comparative transcriptome profiling of both fungi growing on SEB as carbon source.ResultsParticular attention was focused on CAZymes, sugar transporters, transcription factors (TFs) and other proteins related to lignocellulose degradation. Although genes coding for the main enzymes involved in biomass deconstruction were expressed by both fungal strains since the beginning of the growth in SEB, significant differences were found in their expression profiles. The expression of these enzymes is mainly regulated at the transcription level, and A. niger and T. reesei also showed differences in TFs content and in their expression. Several sugar transporters that were induced in both fungal strains could be new players on biomass degradation besides their role in sugar uptake. Interestingly, our findings revealed that in both strains several genes that code for proteins of unknown function and pro-oxidant, antioxidant, and detoxification enzymes were induced during growth in SEB as carbon source, but their specific roles on lignocellulose degradation remain to be elucidated.ConclusionsThis is the first report of a time-course experiment monitoring the degradation of pretreated bagasse by two important fungi using the RNA-seq technology. It was possible to identify a set of genes that might be applied in several biotechnology fields. The data suggest that these two microorganisms employ different strategies for biomass breakdown. This knowledge can be exploited for the rational design of enzymatic cocktails and 2G ethanol production improvement.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-017-3857-5) contains supplementary material, which is available to authorized users.

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“…This distinctive character of enhancing NAD level in response to the multiple inhibitors may endue K. marxianus intrinsic considerate inhibitors tolerance especially to furfural and HMF, which was reported in our and other previous study. 13,14 These results give us a hint that improving the amount of NAD + and NADH may enhance the yeast tolerance to lignocellulosic inhibitors. In addition, YCT1 encoding high affinity cysteine transporter and KMAR_40340 encoding cystine transporter were upregulated with the multiple inhibitors stress.…”

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confidence: 91%

Transcriptomic analysis of thermotolerant yeastKluyveromyces marxianusin multiple inhibitors tolerance

Wang

Yang

et al. 2018

RSC Adv.

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During pretreatment of lignocellulosic biomass, toxic compounds were released and inhibited the growth and fermentation of microorganisms. Here the global transcriptional response of K. marxianus to multiple inhibitors including acetic acid, phenols, furfural and HMF, at 42 C, was studied, via RNA-seq technology.Genes involved in the glycolysis pathway, fatty acid metabolism, ergosterol metabolism and vitamin B6 and B1 metabolic process were enriched in the down-regulated gene set, while genes involved in TCA cycle, respiratory chain, ROS detoxification and transporter coding genes were enriched in the up-regulated gene set in response to the multiple inhibitors stress. Further real time-PCR results with three single inhibitor stress conditions showed that different transporters responded quite differently to different inhibitor stress. Coenzyme assay results showed that the level of NAD + was increased and both NADH/ NAD + and NADPH/NADP + ratio decreased. Furthermore, genes involved with transcription factors related to carbohydrate metabolism, sulfur amino acids metabolism, lipid metabolism or those directly involved in the transcriptional process were significantly regulated. Though belonging to different GO categories or KEGG pathway, many differentially expressed genes were enriched in maintaining the redox balance, NAD(P) + /NAD(P)H homeostasis or NAD + synthesis, energy production, and iron transportation or metabolism. These results suggest that engineering these aspects represents a possible strategy to develop more robust strains for industrial fermentation from cellulosic biomass.

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Simultaneous fermentation of glucose and xylose at elevated temperatures co-produces ethanol and xylitol through overexpression of a xylose-specific transporter in engineered Kluyveromyces marxianus

Cited by 56 publications

References 33 publications

High throughput, colorimetric screening of microbial ester biosynthesis reveals high ethyl acetate production from Kluyveromyces marxianus on C5, C6, and C12 carbon sources

High throughput, colorimetric screening of microbial ester biosynthesis reveals high ethyl acetate production from Kluyveromyces marxianus on C5, C6, and C12 carbon sources

Comparative transcriptome analysis reveals different strategies for degradation of steam-exploded sugarcane bagasse by Aspergillus niger and Trichoderma reesei

Transcriptomic analysis of thermotolerant yeastKluyveromyces marxianusin multiple inhibitors tolerance

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