Publications by authors named "Xuena Guo"

β-Caryophyllene is a plant-derived bicyclic sesquiterpene with multiple biological functions. β-Caryophyllene production by engineered represents a promising technological route. However, the low catalytic activity of β-caryophyllene synthase (CPS) is one of the main restrictive factors for β-caryophyllene production.

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Cat8 is an important transcription factor regulating the utilization of non-fermentative carbon sources in . However, our previous studies found that Cat8 may play a critical role in nitrogen metabolism, but the regulatory mechanism has not been elucidated. In this study, the nuclear localization and analysis of regulatory activity showed that the Cat8 function relies on Snf1 kinase.

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Copper is an essential micronutrient for life, whose homeostasis is rigorously regulated to meet the demands of normal biological processes and to minimize the potential toxicity. Copper enriched by yeast is regarded as a safe and bioavailable form of copper supplements. Here, a mutant strain H247 with expanded storage capability of copper was obtained through atmospheric and room-temperature plasma treatment.

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Mevalonate (MVA) pathway is the core for terpene and sterol biosynthesis, whose metabolic flux influences the synthesis efficiency of such compounds. Saccharomyces cerevisiae is an attractive chassis for the native active MVA pathway. Here, the truncated form of Enterococcus faecalis MvaE with only 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) activity was found to be the most effective enzyme for MVA pathway flux using squalene as the metabolic marker, resulting in 431-fold and 9-fold increases of squalene content in haploid and industrial yeast strains respectively.

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Carotenoids are unsaturated compounds with terpene groups. Among them, astaxanthin has strong antioxidant properties. It is widely used in aquaculture, food, medicine, and cosmetics with a broad market prospect.

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Copper is an essential trace element for living organisms. Copper enriched by yeast of Saccharomyces cerevisiae is regarded as the biologically available organic copper supplement with great potentiality for application. However, the lower uptake ratio of copper ions makes the production of copper enriched by yeast uneconomically and environmentally unfriendly.

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Transcriptional downregulation is widely used for metabolic flux control. Here, , a cis-element of operator, was explored to engineer promoters of for downregulation. First, the promoter (P) and its enhanced variant P were engineered by insertion of into different sites, which resulted in decrease in both transcription and GFP fluorescence intensity to various degrees.

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Background: Saccharomyces cerevisiae is well-known as an ideal model system for basic research and important industrial microorganism for biotechnological applications. Acetic acid is an important growth inhibitor that has deleterious effects on both the growth and fermentation performance of yeast cells. Comprehensive understanding of the mechanisms underlying S.

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Background: 2-phenylethanol (2-PE) is an important aromatic compound with a lovely rose-like scent. Saccharomyces cerevisiae is a desirable microbe for 2-PE production but its natural yield is not high, and one or two crucial genes' over-expression in S. cerevisiae did not improve 2-PE greatly.

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In Saccharomyces cerevisiae, when l-phenylalanine (l-Phe) is used as the sole nitrogen source, 2-phenylethanol (PE) is mainly synthesized via the Ehrlich pathway. General amino acid permease Gap1p is response of aromatic amino acids transportation, and GATA transcription factors Gln3p and Gat1p regulate the transcription of permease gene and catabolic enzyme genes for nitrogen sources and aromatic amino acids utilization. In this study, it was demonstrated that over-expressing GLN3 gene from industrial yeast strain MT2 or S.

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2-Phenylethanol (2-PE) is widely used in food, perfume and pharmaceutical industry, but lower production in microbes and less known regulatory mechanisms of 2-PE make further study necessary. In this study, crucial genes like ARO8 and ARO10 of Ehrlich pathway for 2-PE synthesis and key transcription factor ARO80 in Saccharomyces cerevisiae were re-regulated using constitutive promoter; in the meantime, the effect of nitrogen source in synthetic complete (SC) medium with L-phenylalanine (L-Phe) on Aro8/Aro9 and Aro10 was investigated. The results showed that aromatic aminotransferase activities of ARO8 over-expressing strains were seriously inhibited by ammonia sulfate in SC + Phe medium.

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Yeast cells are challenged by various environmental stresses in the process of industrial fermentation. As the currently main organism for bio-ethanol production, Saccharomyces cerevisiae suffers from ethanol stress. Some amino acids have been reported to be related to yeast tolerance to stresses.

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High-performance liquid chromatography was used to separate Cr(III) and Cr(VI) in samples with detection by inductively coupled plasma mass spectrometry(ICP-MS). The separation was achieved on a weak anion exchange column. The mobile phase was pH 7.

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With increasing application of Hansenula polymorpha in fundamental research and biotechnology, many more genetic manipulations are required. However, these have been restricted for the finiteness of selectable markers. Here, MazF, a toxin protein from Escherichia coli, was investigated as a counter-selectable marker in H.

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Ergosterol is an economically important metabolite produced by yeast. To improve the production of ergosterol by Saccharomyces cerevisiae YEH56 (pHXA42) from molasses, a cheap and regenerative material, different strategies were applied. First, Plackett-Burman design and central composite design were applied to screen the significant factors in fermentation medium using ergosterol yield (g/L) as the response value.

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Objective: Many tandem repeats exist in FLO1 gene of Saccharomyces cerevisiae, which might have great regulatory effect on the conformation and function of flocculation protein (flocculin). In this study, we analyzed the effect of 3'-terminal tandem repeats B, C and D complete deletion on the function of flocculin.

Methods: We constructed the derived gene FLO1 bcd with complete deletion of tandem repeats B, C and D of FLO1 by fusion PCR.

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Yeast flocculation is described as a reversible, asexual and calcium dependent process, in which cells adhere to form flocs by interaction of specific cell surface proteins named flocculins on yeast cells with mannose residues present on the cell wall of adjacent yeast cells. Yeast flocculation provides a very economical and convenient pathway for separation of yeast cells from the fermentation broth or removal of heavy metal ions from effluent. A large number of tandem repeats have been found in genes encoding flocculins, which not only have great regulatory effect on the structure and function of flocculins, generating the diversity of flocculation characteristics, but lead to genetic instability in flocculation as well for driving slippage and recombination reactions within and between FLO genes.

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Objective: There are a large number of tandem repeats in FLO1, which are highly dynamic components in genome leading to the unstable flocculation profiles in Saccharomyces cerevisiae. The effects of complete or partial deletion of repeated DNA sequence A in FLO1 on the flocculation characteristics and genetic stability in yeast were studied to provide theoretical guide for construction genetically stable flocculation gene with minimal size.

Methods: We constructed the derived gene FLO1a with complete deletion of repeated DNA sequence A in the central domain by fusion PCR, and isolated the derived genes FLO1a1 - FLO1a5 with partial deletion of repeated DNA sequence A at different sites using E.

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Flocculation is an attractive property for Saccaromyces cerevisiae, which plays important roles in fermentation industry and environmental remediation. The process of flocculation is mediated by a family of cell surface flocculins. As one member of flocculins, Flo1 is characterized by four families of repeats (designated as repeat units A, B, C and D) in the central domain.

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Objective: There are a large numbers of tandem repeats in FLO1, which are highly dynamic components in genome leading to the unstable flocculation profiles in Saccharomyces cerevisiae. The effects of repeated unite B or D deletion on the function of flocculation protein was studied to provide theory basis for constructing genetically stable flocculation gene with minimal size.

Methods: We cloned the intact flocculation gene FLO1 from S.

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Bioethanol is an attractive alternative to fossil fuels. Saccharomyces cerevisiae is the most important ethanol producer. However, yeast cells are challenged by various environmental stresses during the industrial process of ethanol production.

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The FPS1 gene coding for the Fps1p aquaglyceroporin protein of an industrial strain of Saccharomyces cerevisiae was disrupted by inserting CUP1 gene. Wild-type strain, CE25, could only grow on YPD medium containing less than 0.45% (v/v) acetic acid, while recombinant strain T12 with FPS1 disruption could grow on YPD medium with 0.

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In this study, the problems of high caloric content, increased maturation time and off-flavors in commercial beer manufacture arising from residual sugar, diacetyl, and acetaldehyde levels were addressed. A recombinant industrial brewing yeast strain (TQ1) was generated from T1 [Lipomyces starkeyi dextranase gene (LSD1) introduced, alpha-acetohydroxyacid synthase gene (ILV2) disrupted] by introducing Saccharomyces cerevisiae glucoamylase (SGA1) and a strong promoter PGK1 while disrupting the genes coding alcohol dehydrogenase (ADH2). The highest glucoamylase activity for TQ1 was 93.

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The heterologously expressed L1 protein of human papilomavirus 16 can assembly into virus-like particles (VLPs), which has been used as prophylactic vaccine for cervical carcinoma. To express L1 protein in Hansenula polymorpha, we analyzed the codon usage of the native gene of L1 protein and redesigned the encoding sequence according to the codon bias of H. polymorpha.

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Uricase is an important medical enzyme which can be used to determine urate in clinical analysis, to therapy gout, hyperuricemia, and tumor lysis syndrome. Uricase of Candida utilis was successfully expressed in Hansenula polymorpha under the control of methanol oxidase promoter using Saccharomyces cerevisiae alpha-factor signal peptide as the secretory sequence. Recombinant H.

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