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Sample records for candida tenuis xylose

  1. Genome sequence and physiological analysis of Yamadazyma laniorum f.a. sp. nov. and a reevaluation of the apocryphal xylose fermentation of its sister species, Candida tenuis.

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    Haase, Max A B; Kominek, Jacek; Langdon, Quinn K; Kurtzman, Cletus P; Hittinger, Chris Todd

    2017-05-01

    Xylose fermentation is a rare trait that is immensely important to the cellulosic biofuel industry, and Candida tenuis is one of the few yeasts that has been reported with this trait. Here we report the isolation of two strains representing a candidate sister species to C. tenuis. Integrated analysis of genome sequence and physiology suggested the genetic basis of a number of traits, including variation between the novel species and C. tenuis in lactose metabolism due to the loss of genes encoding lactose permease and β-galactosidase in the former. Surprisingly, physiological characterization revealed that neither the type strain of C. tenuis nor this novel species fermented xylose in traditional assays. We reexamined three xylose-fermenting strains previously identified as C. tenuis and found that these strains belong to the genus Scheffersomyces and are not C. tenuis. We propose Yamadazyma laniorum f.a. sp. nov. to accommodate our new strains and designate its type strain as yHMH7 (=CBS 14780 = NRRL Y-63967T). Furthermore, we propose the transfer of Candida tenuis to the genus Yamadazyma as Yamadazyma tenuis comb. nov. This approach provides a roadmap for how integrated genome sequence and physiological analysis can yield insight into the mechanisms that generate yeast biodiversity. Published by Oxford University Press on behalf of FEMS 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  2. The structure of apo and holo forms of xylose reductase, a dimeric aldo-keto reductase from Candida tenuis.

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    Kavanagh, Kathryn L; Klimacek, Mario; Nidetzky, Bernd; Wilson, David K

    2002-07-16

    Xylose reductase is a homodimeric oxidoreductase dependent on NADPH or NADH and belongs to the largely monomeric aldo-keto reductase superfamily of proteins. It catalyzes the first step in the assimilation of xylose, an aldose found to be a major constituent monosaccharide of renewable plant hemicellulosic material, into yeast metabolic pathways. It does this by reducing open chain xylose to xylitol, which is reoxidized to xylulose by xylitol dehydrogenase and metabolically integrated via the pentose phosphate pathway. No structure has yet been determined for a xylose reductase, a dimeric aldo-keto reductase or a family 2 aldo-keto reductase. The structures of the Candida tenuis xylose reductase apo- and holoenzyme, which crystallize in spacegroup C2 with different unit cells, have been determined to 2.2 A resolution and an R-factor of 17.9 and 20.8%, respectively. Residues responsible for mediating the novel dimeric interface include Asp-178, Arg-181, Lys-202, Phe-206, Trp-313, and Pro-319. Alignments with other superfamily members indicate that these interactions are conserved in other dimeric xylose reductases but not throughout the remainder of the oligomeric aldo-keto reductases, predicting alternate modes of oligomerization for other families. An arrangement of side chains in a catalytic triad shows that Tyr-52 has a conserved function as a general acid. The loop that folds over the NAD(P)H cosubstrate is disordered in the apo form but becomes ordered upon cosubstrate binding. A slow conformational isomerization of this loop probably accounts for the observed rate-limiting step involving release of cosubstrate. Xylose binding (K(m) = 87 mM) is mediated by interactions with a binding pocket that is more polar than a typical aldo-keto reductase. Modeling of xylose into the active site of the holoenzyme using ordered waters as a guide for sugar hydroxyls suggests a convincing mode of substrate binding.

  3. Systematic strain construction and process development: Xylitol production by Saccharomyces cerevisiae expressing Candida tenuis xylose reductase in wild-type or mutant form.

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    Pratter, S M; Eixelsberger, T; Nidetzky, B

    2015-12-01

    A novel Saccharomyces cerevisiae whole-cell biocatalyst for xylitol production based on Candida tenuis xylose reductase (CtXR) is presented. Six recombinant strains expressing wild-type CtXR or an NADH-specific mutant were constructed and evaluated regarding effects of expression mode, promoter strength, biocatalyst concentration and medium composition. Intracellular XR activities ranged from 0.09 U mgProt(-1) to 1.05 U mgProt(-1) but did not correlate with the strains' xylitol productivities, indicating that other factors limited xylose conversion in the high-activity strains. The CtXR mutant decreased the biocatalyst's performance, suggesting use of the NADPH-preferring wild-type enzyme when (semi-)aerobic conditions are applied. In a bioreactor process, the best-performing strain converted 40 g L(-1) xylose with an initial productivity of 1.16 g L(-1)h(-1) and a xylitol yield of 100%. The obtained results underline the potential of CtXR wild-type for xylose reduction and point out parameters to improve "green" xylitol production. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Whole-cell bioreduction of aromatic α-keto esters using Candida tenuis xylose reductase and Candida boidinii formate dehydrogenase co-expressed in Escherichia coli

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    Egger Sigrid

    2008-12-01

    Full Text Available Abstract Background Whole cell-catalyzed biotransformation is a clear process option for the production of chiral alcohols via enantioselective reduction of precursor ketones. A wide variety of synthetically useful reductases are expressed heterologously in Escherichia coli to a high level of activity. Therefore, this microbe has become a prime system for carrying out whole-cell bioreductions at different scales. The limited capacity of central metabolic pathways in E. coli usually requires that reductase coenzyme in the form of NADPH or NADH be regenerated through a suitable oxidation reaction catalyzed by a second NADP+ or NAD+ dependent dehydrogenase that is co-expressed. Candida tenuis xylose reductase (CtXR was previously shown to promote NADH dependent reduction of aromatic α-keto esters with high Prelog-type stereoselectivity. We describe here the development of a new whole-cell biocatalyst that is based on an E. coli strain co-expressing CtXR and formate dehydrogenase from Candida boidinii (CbFDH. The bacterial system was evaluated for the synthesis of ethyl R-4-cyanomandelate under different process conditions and benchmarked against a previously described catalyst derived from Saccharomyces cerevisiae expressing CtXR. Results Gene co-expression from a pETDuet-1 vector yielded about 260 and 90 units of intracellular CtXR and CbFDH activity per gram of dry E. coli cell mass (gCDW. The maximum conversion rate (rS for ethyl 4-cyanobenzoylformate by intact or polymyxin B sulphate-permeabilized cells was similar (2 mmol/gCDWh, suggesting that the activity of CbFDH was partly rate-limiting overall. Uncatalyzed ester hydrolysis in substrate as well as inactivation of CtXR and CbFDH in the presence of the α-keto ester constituted major restrictions to the yield of alcohol product. Using optimized reaction conditions (100 mM substrate; 40 gCDW/L, we obtained ethyl R-4-cyanomandelate with an enantiomeric excess (e.e. of 97.2% in a yield of 82

  5. Characterization of xylose reductase from Candida tropicalis ...

    African Journals Online (AJOL)

    USER

    2010-08-02

    Aug 2, 2010 ... production are the possibility of using industrial side- streams as raw ... xylitol production,. D-xylose assimilation in microorganism involves xylose ..... natural biopolymer extracted from brown alga, and in the presence of ...

  6. Conversion of xylose to ethanol under aerobic conditions by Candida tropicalis

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    T. W. Jeffries

    1981-01-01

    Candida tropicalis converts xylose to ethanol under aerobic, but not anaerobic, conditions. Ethanol production lags behind growth and is accelerated by increased aeration. Adding xylose to active cultures stimulates ethanol production as does serial subculture in a medium containing xylose as a sole carbon source.

  7. Furfural and glucose can enhance conversion of xylose to xylitol by Candida magnoliae TISTR 5663.

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    Wannawilai, Siwaporn; Lee, Wen-Chien; Chisti, Yusuf; Sirisansaneeyakul, Sarote

    2017-01-10

    Xylitol production from xylose by the yeast Candida magnoliae TISTR 5663 was enhanced by supplementing the fermentation medium with furfural (300mg/L) and glucose (3g/L with an initial mass ratio of glucose to xylose of 1:10) together under oxygen limiting conditions. In the presence of furfural and glucose, the final concentration of xylitol was unaffected relative to control cultures but the xylitol yield on xylose increased by about 5%. Supplementation of the culture medium with glucose alone at an initial concentration of 3g/L, stimulated the volumetric and specific rates of xylose consumption and the rate of xylitol production from xylose. In a culture medium containing 30g/L xylose, 300mg/L furfural and 3g/L glucose, the volumetric production rate of xylitol was 1.04g/L h and the specific production rate was 0.169g/g h. In the absence of furfural and glucose, the volumetric production rate of xylitol was ∼35% lower and the specific production rate was nearly 30% lower. In view of these results, xylose-containing lignocellulosic hydrolysates contaminated with furfural can be effectively used for producing xylitol by fermentation so long as the glucose-to-xylose mass ratio in the hydrolysate does not exceed 1:10 and the furfural concentration is ≤300mg/L. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Optimized Production of Xylitol from Xylose Using a Hyper-Acidophilic Candida tropicalis

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    Elena Tamburini

    2015-08-01

    Full Text Available The yeast Candida tropicalis DSM 7524 produces xylitol, a natural, low-calorie sweetener, by fermentation of xylose. In order to increase xylitol production rate during the submerged fermentation process, some parameters-substrate (xylose concentration, pH, aeration rate, temperature and fermentation strategy-have been optimized. The maximum xylitol yield reached at 60–80 g/L initial xylose concentration, pH 5.5 at 37 °C was 83.66% (w/w on consumed xylose in microaerophilic conditions (kLa = 2·h−1. Scaling up on 3 L fermenter, with a fed-batch strategy, the best xylitol yield was 86.84% (w/w, against a 90% of theoretical yield. The hyper-acidophilic behaviour of C. tropicalis makes this strain particularly promising for industrial application, due to the possibility to work in non-sterile conditions.

  9. Optimized Production of Xylitol from Xylose Using a Hyper-Acidophilic Candida tropicalis.

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    Tamburini, Elena; Costa, Stefania; Marchetti, Maria Gabriella; Pedrini, Paola

    2015-08-19

    The yeast Candida tropicalis DSM 7524 produces xylitol, a natural, low-calorie sweetener, by fermentation of xylose. In order to increase xylitol production rate during the submerged fermentation process, some parameters-substrate (xylose) concentration, pH, aeration rate, temperature and fermentation strategy-have been optimized. The maximum xylitol yield reached at 60-80 g/L initial xylose concentration, pH 5.5 at 37 °C was 83.66% (w/w) on consumed xylose in microaerophilic conditions (kLa = 2·h(-1)). Scaling up on 3 L fermenter, with a fed-batch strategy, the best xylitol yield was 86.84% (w/w), against a 90% of theoretical yield. The hyper-acidophilic behaviour of C. tropicalis makes this strain particularly promising for industrial application, due to the possibility to work in non-sterile conditions.

  10. Improved Ethanol Production from Xylose by Candida shehatae Induced by Dielectric Barrier Discharge Air Plasma

    International Nuclear Information System (INIS)

    Chen Huixia; Xiu Zhilong; Bai Fengwu

    2014-01-01

    Xylose fermentation is essential for ethanol production from lignocellulosic biomass. Exposure of the xylose-fermenting yeast Candida shehatae (C. shehatae) CICC1766 to atmospheric pressure dielectric barrier discharge (DBD) air plasma yields a clone (designated as C81015) with stability, which exhibits a higher ethanol fermentation rate from xylose, giving a maximal enhancement in ethanol production of 36.2% compared to the control (untreated). However, the biomass production of C81015 is lower than that of the control. Analysis of the NADH (nicotinamide adenine dinucleotide)- and NADPH (nicotinamide adenine dinucleotide phosphate)-linked xylose reductases and NAD + -linked xylitol dehydrogenase indicates that their activities are enhanced by 34.1%, 61.5% and 66.3%, respectively, suggesting that the activities of these three enzymes are responsible for improving ethanol fermentation in C81015 with xylose as a substrate. The results of this study show that DBD air plasma could serve as a novel and effective means of generating microbial strains that can better use xylose for ethanol fermentation

  11. Improved Ethanol Production from Xylose by Candida shehatae Induced by Dielectric Barrier Discharge Air Plasma

    Science.gov (United States)

    Chen, Huixia; Xiu, Zhilong; Bai, Fengwu

    2014-06-01

    Xylose fermentation is essential for ethanol production from lignocellulosic biomass. Exposure of the xylose-fermenting yeast Candida shehatae (C. shehatae) CICC1766 to atmospheric pressure dielectric barrier discharge (DBD) air plasma yields a clone (designated as C81015) with stability, which exhibits a higher ethanol fermentation rate from xylose, giving a maximal enhancement in ethanol production of 36.2% compared to the control (untreated). However, the biomass production of C81015 is lower than that of the control. Analysis of the NADH (nicotinamide adenine dinucleotide)- and NADPH (nicotinamide adenine dinucleotide phosphate)-linked xylose reductases and NAD+-linked xylitol dehydrogenase indicates that their activities are enhanced by 34.1%, 61.5% and 66.3%, respectively, suggesting that the activities of these three enzymes are responsible for improving ethanol fermentation in C81015 with xylose as a substrate. The results of this study show that DBD air plasma could serve as a novel and effective means of generating microbial strains that can better use xylose for ethanol fermentation.

  12. De Novo Assembly of Candida sojae and Candida boidinii Genomes, Unexplored Xylose-Consuming Yeasts with Potential for Renewable Biochemical Production

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    Borelli, Guilherme; José, Juliana; Teixeira, Paulo José Pereira Lima; dos Santos, Leandro Vieira

    2016-01-01

    Candida boidinii and Candida sojae yeasts were isolated from energy cane bagasse and plague-insects. Both have fast xylose uptake rate and produce great amounts of xylitol, which are interesting features for food and 2G ethanol industries. Because they lack published genomes, we have sequenced and assembled them, offering new possibilities for gene prospection. PMID:26769937

  13. Production of Xylitol from D-Xylose by Overexpression of Xylose Reductase in Osmotolerant Yeast Candida glycerinogenes WL2002-5.

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    Zhang, Cheng; Zong, Hong; Zhuge, Bin; Lu, Xinyao; Fang, Huiying; Zhuge, Jian

    2015-07-01

    Efficient bioconversion of D-xylose into various biochemicals is critical for the developing lignocelluloses application. In this study, we compared D-xylose utilization in Candida glycerinogenes WL2002-5 transformants expressing xylose reductase (XYL1) in D-xylose metabolism. C. glycerinogenes WL2002-5 expressing XYL1 from Schefferomyces stipitis can produce xylitol. Xylitol production by the recombinant strains was evaluated using a xylitol fermentation medium with glucose as a co-substrate. As glucose was found to be an insufficient co-substrate, various carbon sources were screened for efficient cofactor regeneration, and glycerol was found to be the best co-substrate. The effects of glycerol on the xylitol production rate by a xylose reductase gene (XYL1)-overexpressed mutant of C. glycerinogenes WL2002-5 were investigated. The XYL1-overexpressed mutant produced xylitol from D-xylose using glycerol as a co-substrate for cell growth and NAD (P) H regeneration: 100 g/L D-xylose was completely converted into xylitol when at least 20 g/L glycerol was used as a co-substrate. XYL1 overexpressed mutant grown on glycerol as co-substrate accumulated 2.1-fold increased xylitol concentration over those cells grown on glucose as co-substrate. XYL1 overexpressed mutant produced xylitol with a volumetric productivity of 0.83 g/L/h, and a xylitol yield of 98 % xylose. Recombinant yeast strains obtained in this study are promising candidates for xylitol production. This is the first report of XYL1 gene overexpression of C. glycerinogenes WL2002-5 for enhancing the efficiency of xylitol production.

  14. Xylitol production from xylose mother liquor: a novel strategy that combines the use of recombinant Bacillus subtilis and Candida maltosa

    Science.gov (United States)

    2011-01-01

    Background Xylose mother liquor has high concentrations of xylose (35%-40%) as well as other sugars such as L-arabinose (10%-15%), galactose (8%-10%), glucose (8%-10%), and other minor sugars. Due to the complexity of this mother liquor, further isolation of xylose by simple method is not possible. In China, more than 50,000 metric tons of xylose mother liquor was produced in 2009, and the management of sugars like xylose that present in the low-cost liquor is a problem. Results We designed a novel strategy in which Bacillus subtilis and Candida maltosa were combined and used to convert xylose in this mother liquor to xylitol, a product of higher value. First, the xylose mother liquor was detoxified with the yeast C. maltosa to remove furfural and 5-hydromethylfurfural (HMF), which are inhibitors of B. subtilis growth. The glucose present in the mother liquor was also depleted by this yeast, which was an added advantage because glucose causes carbon catabolite repression in B. subtilis. This detoxification treatment resulted in an inhibitor-free mother liquor, and the C. maltosa cells could be reused as biocatalysts at a later stage to reduce xylose to xylitol. In the second step, a recombinant B. subtilis strain with a disrupted xylose isomerase gene was constructed. The detoxified xylose mother liquor was used as the medium for recombinant B. subtilis cultivation, and this led to L-arabinose depletion and xylose enrichment of the medium. In the third step, the xylose was further reduced to xylitol by C. maltosa cells, and crystallized xylitol was obtained from this yeast transformation medium. C. maltosa transformation of the xylose-enriched medium resulted in xylitol with 4.25 g L-1·h-1 volumetric productivity and 0.85 g xylitol/g xylose specific productivity. Conclusion In this study, we developed a biological method for the purification of xylose from xylose mother liquor and subsequent preparation of xylitol by C. maltosa-mediated biohydrogenation of xylose

  15. Xylitol production from xylose mother liquor: a novel strategy that combines the use of recombinant Bacillus subtilis and Candida maltosa

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    Jiang Mingguo

    2011-02-01

    Full Text Available Abstract Background Xylose mother liquor has high concentrations of xylose (35%-40% as well as other sugars such as L-arabinose (10%-15%, galactose (8%-10%, glucose (8%-10%, and other minor sugars. Due to the complexity of this mother liquor, further isolation of xylose by simple method is not possible. In China, more than 50,000 metric tons of xylose mother liquor was produced in 2009, and the management of sugars like xylose that present in the low-cost liquor is a problem. Results We designed a novel strategy in which Bacillus subtilis and Candida maltosa were combined and used to convert xylose in this mother liquor to xylitol, a product of higher value. First, the xylose mother liquor was detoxified with the yeast C. maltosa to remove furfural and 5-hydromethylfurfural (HMF, which are inhibitors of B. subtilis growth. The glucose present in the mother liquor was also depleted by this yeast, which was an added advantage because glucose causes carbon catabolite repression in B. subtilis. This detoxification treatment resulted in an inhibitor-free mother liquor, and the C. maltosa cells could be reused as biocatalysts at a later stage to reduce xylose to xylitol. In the second step, a recombinant B. subtilis strain with a disrupted xylose isomerase gene was constructed. The detoxified xylose mother liquor was used as the medium for recombinant B. subtilis cultivation, and this led to L-arabinose depletion and xylose enrichment of the medium. In the third step, the xylose was further reduced to xylitol by C. maltosa cells, and crystallized xylitol was obtained from this yeast transformation medium. C. maltosa transformation of the xylose-enriched medium resulted in xylitol with 4.25 g L-1·h-1 volumetric productivity and 0.85 g xylitol/g xylose specific productivity. Conclusion In this study, we developed a biological method for the purification of xylose from xylose mother liquor and subsequent preparation of xylitol by C. maltosa

  16. The alcohol dehydrogenase system in the xylose-fermenting yeast Candida maltosa.

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    Yuping Lin

    2010-07-01

    Full Text Available The alcohol dehydrogenase (ADH system plays a critical role in sugar metabolism involving in not only ethanol formation and consumption but also the general "cofactor balance" mechanism. Candida maltosa is able to ferment glucose as well as xylose to produce a significant amount of ethanol. Here we report the ADH system in C. maltosa composed of three microbial group I ADH genes (CmADH1, CmADH2A and CmADH2B, mainly focusing on its metabolic regulation and physiological function.Genetic analysis indicated that CmADH2A and CmADH2B tandemly located on the chromosome could be derived from tandem gene duplication. In vitro characterization of enzymatic properties revealed that all the three CmADHs had broad substrate specificities. Homo- and heterotetramers of CmADH1 and CmADH2A were demonstrated by zymogram analysis, and their expression profiles and physiological functions were different with respect to carbon sources and growth phases. Fermentation studies of ADH2A-deficient mutant showed that CmADH2A was directly related to NAD regeneration during xylose metabolism since CmADH2A deficiency resulted in a significant accumulation of glycerol.Our results revealed that CmADH1 was responsible for ethanol formation during glucose metabolism, whereas CmADH2A was glucose-repressed and functioned to convert the accumulated ethanol to acetaldehyde. To our knowledge, this is the first demonstration of function separation and glucose repression of ADH genes in xylose-fermenting yeasts. On the other hand, CmADH1 and CmADH2A were both involved in ethanol formation with NAD regeneration to maintain NADH/NAD ratio in favor of producing xylitol from xylose. In contrast, CmADH2B was expressed at a much lower level than the other two CmADH genes, and its function is to be further confirmed.

  17. Fermentation of mixed glucose-xylose substrates by engineered strains of Saccharomyces cerevisiae: role of the coenzyme specificity of xylose reductase, and effect of glucose on xylose utilization

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    Klimacek Mario

    2010-03-01

    Full Text Available Abstract Background In spite of the substantial metabolic engineering effort previously devoted to the development of Saccharomyces cerevisiae strains capable of fermenting both the hexose and pentose sugars present in lignocellulose hydrolysates, the productivity of reported strains for conversion of the naturally most abundant pentose, xylose, is still a major issue of process efficiency. Protein engineering for targeted alteration of the nicotinamide cofactor specificity of enzymes catalyzing the first steps in the metabolic pathway for xylose was a successful approach of reducing xylitol by-product formation and improving ethanol yield from xylose. The previously reported yeast strain BP10001, which expresses heterologous xylose reductase from Candida tenuis in mutated (NADH-preferring form, stands for a series of other yeast strains designed with similar rational. Using 20 g/L xylose as sole source of carbon, BP10001 displayed a low specific uptake rate qxylose (g xylose/g dry cell weight/h of 0.08. The study presented herein was performed with the aim of analysing (external factors that limit qxylose of BP10001 under xylose-only and mixed glucose-xylose substrate conditions. We also carried out a comprehensive investigation on the currently unclear role of coenzyme utilization, NADPH compared to NADH, for xylose reduction during co-fermentation of glucose and xylose. Results BP10001 and BP000, expressing C. tenuis xylose reductase in NADPH-preferring wild-type form, were used. Glucose and xylose (each at 10 g/L were converted sequentially, the corresponding qsubstrate values being similar for each strain (glucose: 3.0; xylose: 0.05. The distribution of fermentation products from glucose was identical for both strains whereas when using xylose, BP10001 showed enhanced ethanol yield (BP10001 0.30 g/g; BP000 0.23 g/g and decreased yields of xylitol (BP10001 0.26 g/g; BP000 0.36 g/g and glycerol (BP10001 0.023 g/g; BP000 0.072 g/g as compared

  18. PENGARUH Ph, KADAR XILOSA DAN KADAR GLUKOSA TERHADAP PRODUKSI XYLITOL OLEH Candida shehatae WAY 08 [The Influence of Intial Xylose and Glucose Consentration on Xylitol production by Candida shehatae WAY 08

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    Wisnu Adi Yulianto 1

    2001-08-01

    Full Text Available The objectiviea of this research were to determine the optimum culture conditions of initial pH, xylose and glucose concentration for xylitol production by Candida shehatae WAY 08. The initial pH was altered whitin the range of 4-7, the xylose concentration from 5020%, and the glucose (cosubstrate from 0-4%. The fermentation was performed at 30°C in 500 ml erlenmeyer flaks placed in a shaker incubator at 250 rpm for 7d. biomas concentration war determined by oven method. Xylose, glucose and xylitol concentrations were determined by HPCL.the result incated that the highest xylitol volumetric productivity of Candida shehatae WAY 08 was 0,314 g/I/h at the initial pH of 5 in medium containing 150 g/I xylose. Addition of glucose into media inhibited the xylitol production, but in creased the xylitol yield.

  19. Comparative genomics of xylose-fermenting fungi for enhanced biofuel production

    Energy Technology Data Exchange (ETDEWEB)

    Wohlbach, Dana J.; Kuo, Alan; Sato, Trey K.; Potts, Katlyn M.; Salamov, Asaf A.; LaButti, Kurt M.; Sun, Hui; Clum, Alicia; Pangilinan, Jasmyn L.; Lindquist, Erika A.; Lucas, Susan; Lapidus, Alla; Jin, Mingjie; Gunawan, Christa; Balan, Venkatesh; Dale, Bruce E.; Jeffries, Thomas W.; Zinkel, Robert; Barry, Kerrie W.; Grigoriev, Igor V.; Gasch, Audrey P.

    2011-02-24

    Cellulosic biomass is an abundant and underused substrate for biofuel production. The inability of many microbes to metabolize the pentose sugars abundant within hemicellulose creates specific challenges for microbial biofuel production from cellulosic material. Although engineered strains of Saccharomyces cerevisiae can use the pentose xylose, the fermentative capacity pales in comparison with glucose, limiting the economic feasibility of industrial fermentations. To better understand xylose utilization for subsequent microbial engineering, we sequenced the genomes of two xylose-fermenting, beetle-associated fungi, Spathaspora passalidarum and Candida tenuis. To identify genes involved in xylose metabolism, we applied a comparative genomic approach across 14 Ascomycete genomes, mapping phenotypes and genotypes onto the fungal phylogeny, and measured genomic expression across five Hemiascomycete species with different xylose-consumption phenotypes. This approach implicated many genes and processes involved in xylose assimilation. Several of these genes significantly improved xylose utilization when engineered into S. cerevisiae, demonstrating the power of comparative methods in rapidly identifying genes for biomass conversion while reflecting on fungal ecology.

  20. Improvement on D-xylose to Xylitol Biotransformation by Candida guilliermondii Using Cells Permeabilized with Triton X-100 and Selected Process Conditions.

    Science.gov (United States)

    Cortez, Daniela Vieira; Mussatto, Solange I; Roberto, Inês Conceição

    2016-11-01

    Cells of Candida guilliermondii permeabilized with Triton X-100 were able to efficiently produce xylitol from a medium composed only by D-xylose and MgCl 2 ·6H 2 O in potassium phosphate buffer, at 35 °C and pH 6.5. Under these conditions, the results were similar to those obtained when cofactor and co-substrate or nutrients were added to the medium (about 95 % D-xylose was assimilated producing 42 g/L of xylitol, corresponding to 0.80 g/g yield and 2.65 g/L h volumetric productivity). Furthermore, the permeabilized cells kept the D-xylose assimilation in about 90 % and the xylitol production in approx. 40 g/L during three bioconversion cycles of 16 h each. These values are highly relevant when compared to others reported in the literature using enzyme technology and fermentative process, thereby demonstrating the effectiveness of the proposed method. The present study reveals that the use of permeabilized cells is an interesting alternative to obtain high xylitol productivity using low cost medium formulation. This approach may allow the future development of xylitol production from xylose present in lignocellulosic biomass, with additional potential for implementation in biorefinery strategies.

  1. Single-cell Protein and Xylitol Production by a Novel Yeast Strain Candida intermedia FL023 from Lignocellulosic Hydrolysates and Xylose.

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    Wu, Jiaqiang; Hu, Jinlong; Zhao, Shumiao; He, Mingxiong; Hu, Guoquan; Ge, Xiangyang; Peng, Nan

    2018-05-01

    Yeasts are good candidates to utilize the hydrolysates of lignocellulose, the most abundant bioresource, for bioproducts. This study aimed to evaluate the efficiencies of single-cell protein (SCP) and xylitol production by a novel yeast strain, Candida intermedia FL023, from lignocellulosic hydrolysates and xylose. This strain efficiently assimilated hexose, pentose, and cellubiose for cell mass production with the crude protein content of 484.2 g kg -1 dry cell mass. SCP was produced by strain FL023 using corncob hydrolysate and urea as the carbon and nitrogen sources with the dry cell mass productivity 0.86 g L -1  h -1 and the yield of 0.40 g g -1 sugar. SCP was also produced using NaOH-pretreated Miscanthus sinensis straw and corn steep liquor as the carbon and nitrogen sources through simultaneous saccharification and fermentation with the dry cell productivity of 0.23 g L -1  h -1 and yield of 0.17 g g -1 straw. C. intermedia FL023 was tolerant to 0.5 g L -1 furfural, acetic acid, and syringaldehyde in xylitol fermentation and produced 45.7 g L -1 xylitol from xylose with the productivity of 0.38 g L -1  h -1 and the yield of 0.57 g g -1 xylose. This study provides feasible methods for feed and food additive production from the abundant lignocellulosic bioresources.

  2. Effects of lignin-derived phenolic compounds on xylitol production and key enzyme activities by a xylose utilizing yeast Candida athensensis SB18.

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    Zhang, Jinming; Geng, Anli; Yao, Chuanyi; Lu, Yinghua; Li, Qingbiao

    2012-10-01

    Candida athensensis SB18 is potential xylitol producing yeast isolated in Singapore. It has excellent xylose tolerance and is able to produce xylitol in high titer and yield. However, by-products, such as phenolic compounds, derived in lignocellulosic biomass hydrolysate might negatively influence the performance of this strain for xylitol production. In this work, four potential phenolic inhibitors, such as vanillin, syringaldehyde, 4-hydroxybenzaldehyde and phenol, were evaluated for their inhibitory effects on xylitol production by C. athensensis SB18. Phenol was shown to be the most toxic molecule on this microorganism followed by syringaldehyde. Vanillin and 4-hydroxylbenzaldehyde was less toxic than phenol and syringaldehyde, with vanillin being the least toxic. Inhibition was insignificant when the total content of inhibitors was below 1.0 g/L. The presence of phenolic compounds affected the activity of xylose reductase, however not on that of xylitol dehydrogenase. C. athensensis SB18 is therefore a potential xylitol producer from hemicellulosic hydrolysate due to its assimilation of such phenolic inhibitors. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Xylose reductase and xylitol dehydrogenase activities of Candida guilliermondii as a function of different treatments of sugarcane bagasse hemicellulosic hydrolysate employing experimental design.

    Science.gov (United States)

    Alves, Lourdes A; Vitolo, Michele; Felipe, Maria das Graças A; de Almeida e Silva, João Batista

    2002-01-01

    The sugarcane bagasse hydrolysate, which is rich in xylose, can be used as culture medium for Candida guilliermondii in xylitol production. However, the hydrolysate obtained from bagasse by acid hydrolysis at 120 degrees C for 20 min has by-products (acetic acid and furfural, among others), which are toxic to the yeast over certain concentrations. So, the hydrolysate must be pretreated before using in fermentation. The pretreatment variables considered were: adsorption time (15,37.5, and 60 min), type of acid used (H2So4 and H3Po4), hydrolysate concentration (original, twofold, and fourfold concentrated), and active charcoal (0.5, 1.75 and 3.0%). The suitability of the pretreatment was followed by measuring the xylose reductase (XR) and xylitol dehydrogenase (XD) activity of yeast grown in each treated hydrolysate. The response surface methodology (2(4) full factorial design with a centered face) indicated that the hydrolysate might be concentrated fourfold and the pH adjusted to 7.0 with CaO, followed by reduction to 5.5 with H3PO4. After that it was treated with active charcoal (3.0%) by 60 min. This pretreated hydrolysate attained the high XR/XD ratio of 4.5.

  4. Xylitol production from waste xylose mother liquor containing miscellaneous sugars and inhibitors: one-pot biotransformation by Candida tropicalis and recombinant Bacillus subtilis.

    Science.gov (United States)

    Wang, Hengwei; Li, Lijuan; Zhang, Lebin; An, Jin; Cheng, Hairong; Deng, Zixin

    2016-05-16

    The process of industrial xylitol production is a massive source of organic pollutants, such as waste xylose mother liquor (WXML), a viscous reddish-brown liquid. Currently, WXML is difficult to reuse due to its miscellaneous low-cost sugars, high content of inhibitors and complex composition. WXML, as an organic pollutant of hemicellulosic hydrolysates, accumulates and has become an issue of industrial concern in China. Previous studies have focused only on the catalysis of xylose in the hydrolysates into xylitol using one strain, without considering the removal of other miscellaneous sugars, thus creating an obstacle to subsequent large-scale purification. In the present study, we aimed to develop a simple one-pot biotransformation to produce high-purity xylitol from WXML to improve its economic value. In the present study, we developed a procedure to produce xylitol from WXML, which combines detoxification, biotransformation and removal of by-product sugars (purification) in one bioreactor using two complementary strains, Candida tropicalis X828 and Bacillus subtilis Bs12. At the first stage of micro-aerobic biotransformation, the yeast cells were allowed to grow and metabolized glucose and the inhibitors furfural and hydroxymethyl furfural (HMF), and converted xylose into xylitol. At the second stage of aerobic biotransformation, B. subtilis Bs12 was activated and depleted the by-product sugars. The one-pot process was successfully scaled up from shake flasks to 5, 150 L and 30 m(3) bioreactors. Approximately 95 g/L of pure xylitol could be obtained from the medium containing 400 g/L of WXML at a yield of 0.75 g/g xylose consumed, and the by-product sugars glucose, L-arabinose and galactose were depleted simultaneously. Our results demonstrate that the one-pot procedure is a viable option for the industrial application of WXML to produce value-added chemicals. The integration of complementary strains in the biotransformation of hemicellulosic hydrolysates is

  5. Xylitol production from xylose mother liquor: a novel strategy that combines the use of recombinant Bacillus subtilis and Candida maltosa

    OpenAIRE

    Jiang Mingguo; Lv Jiyang; Wang Ben; Cheng Hairong; Lin Shuangjun; Deng Zixin

    2011-01-01

    Abstract Background Xylose mother liquor has high concentrations of xylose (35%-40%) as well as other sugars such as L-arabinose (10%-15%), galactose (8%-10%), glucose (8%-10%), and other minor sugars. Due to the complexity of this mother liquor, further isolation of xylose by simple method is not possible. In China, more than 50,000 metric tons of xylose mother liquor was produced in 2009, and the management of sugars like xylose that present in the low-cost liquor is a problem. Results We d...

  6. Comparison of heterologous xylose transporters in recombinant Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Hahn-Hägerdal Bärbel

    2010-03-01

    Full Text Available Abstract Background Baker's yeast (Saccharomyces cerevisiae has been engineered for xylose utilization to enable production of fuel ethanol from lignocellulose raw material. One unresolved challenge is that S. cerevisiae lacks a dedicated transport system for pentose sugars, which means that xylose is transported by non-specific Hxt transporters with comparatively low transport rate and affinity for xylose. Results In this study, we compared three heterologous xylose transporters that have recently been shown to improve xylose uptake under different experimental conditions. The transporters Gxf1, Sut1 and At5g59250 from Candida intermedia, Pichia stipitis and Arabidopsis thaliana, respectively, were expressed in isogenic strains of S. cerevisiae and the transport kinetics and utilization of xylose was evaluated. Expression of the Gxf1 and Sut1 transporters led to significantly increased affinity and transport rates of xylose. In batch cultivation at 4 g/L xylose concentration, improved transport kinetics led to a corresponding increase in xylose utilization, whereas no correlation could be demonstrated at xylose concentrations greater than 15 g/L. The relative contribution of native sugar transporters to the overall xylose transport capacity was also estimated during growth on glucose and xylose. Conclusions Kinetic characterization and aerobic batch cultivation of strains expressing the Gxf1, Sut1 and At5g59250 transporters showed a direct relationship between transport kinetics and xylose growth. The Gxf1 transporter had the highest transport capacity and the highest xylose growth rate, followed by the Sut1 transporter. The range in which transport controlled the growth rate was determined to between 0 and 15 g/L xylose. The role of catabolite repression in regulation of native transporters was also confirmed by the observation that xylose transport by native S. cerevisiae transporters increased significantly during cultivation in xylose and

  7. D-xylose absorption

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003606.htm D-xylose absorption To use the sharing features on this page, please enable JavaScript. D-xylose absorption is a laboratory test to determine ...

  8. Genetics of zinc tolerance in Anthoxanthum odoratum and Agrostis tenuis

    Energy Technology Data Exchange (ETDEWEB)

    Gartside, D W; McNeilly, T

    1974-01-01

    The genetic control of zinc tolerance in the grass Anthoxanthum odoratum and Agrostis tenuis has been examined using both the pair cross technique and the diallele analysis procedure used by others. Evidence is presented that the genetic control of zinc tolerance in both species is dominant and directional with a high degree of additive genetic variance.

  9. Xylose fermentation to ethanol

    Energy Technology Data Exchange (ETDEWEB)

    McMillan, J.D.

    1993-01-01

    The past several years have seen tremendous progress in the understanding of xylose metabolism and in the identification, characterization, and development of strains with improved xylose fermentation characteristics. A survey of the numerous microorganisms capable of directly fermenting xylose to ethanol indicates that wild-type yeast and recombinant bacteria offer the best overall performance in terms of high yield, final ethanol concentration, and volumetric productivity. The best performing bacteria, yeast, and fungi can achieve yields greater than 0.4 g/g and final ethanol concentrations approaching 5%. Productivities remain low for most yeast and particularly for fungi, but volumetric productivities exceeding 1.0 g/L-h have been reported for xylose-fermenting bacteria. In terms of wild-type microorganisms, strains of the yeast Pichia stipitis show the most promise in the short term for direct high-yield fermentation of xylose without byproduct formation. Of the recombinant xylose-fermenting microorganisms developed, recombinant E. coli ATTC 11303 (pLOI297) exhibits the most favorable performance characteristics reported to date.

  10. Xylose utilization in recombinant zymomonas

    Science.gov (United States)

    Caimi, Perry G; McCole, Laura; Tao, Luan; Tomb, Jean-Francois; Viitanen, Paul V

    2014-03-25

    Xylose-utilizing Zymomonas strains studied were found to accumulate ribulose when grown in xylose-containing media. Engineering these strains to increase ribose-5-phosphate isomerase activity led to reduced ribulose accumulation, improved growth, improved xylose utilization, and increased ethanol production.

  11. Xylitol production by Debaryomyces hansenii and Candida guilliermondii from rapeseed straw hemicellulosic hydrolysate

    DEFF Research Database (Denmark)

    López-Linares, Juan Carlos; Romero, Inmaculada; Cara, Cristobal

    2018-01-01

    This study evaluated the possibility of using rapeseed straw hemicellulosic hydrolysate as a fermentation medium for xylitol production. Two yeast strains, namely Debaryomyces hansenii and Candida guilliermondii, were used for this bioconversion process and their performance to convert xylose...

  12. Comparing the xylose reductase/xylitol dehydrogenase and xylose isomerase pathways in arabinose and xylose fermenting Saccharomyces cerevisiae strains

    Directory of Open Access Journals (Sweden)

    Hahn-Hägerdal Bärbel

    2008-10-01

    Full Text Available Abstract Background Ethanolic fermentation of lignocellulosic biomass is a sustainable option for the production of bioethanol. This process would greatly benefit from recombinant Saccharomyces cerevisiae strains also able to ferment, besides the hexose sugar fraction, the pentose sugars, arabinose and xylose. Different pathways can be introduced in S. cerevisiae to provide arabinose and xylose utilisation. In this study, the bacterial arabinose isomerase pathway was combined with two different xylose utilisation pathways: the xylose reductase/xylitol dehydrogenase and xylose isomerase pathways, respectively, in genetically identical strains. The strains were compared with respect to aerobic growth in arabinose and xylose batch culture and in anaerobic batch fermentation of a mixture of glucose, arabinose and xylose. Results The specific aerobic arabinose growth rate was identical, 0.03 h-1, for the xylose reductase/xylitol dehydrogenase and xylose isomerase strain. The xylose reductase/xylitol dehydrogenase strain displayed higher aerobic growth rate on xylose, 0.14 h-1, and higher specific xylose consumption rate in anaerobic batch fermentation, 0.09 g (g cells-1 h-1 than the xylose isomerase strain, which only reached 0.03 h-1 and 0.02 g (g cells-1h-1, respectively. Whereas the xylose reductase/xylitol dehydrogenase strain produced higher ethanol yield on total sugars, 0.23 g g-1 compared with 0.18 g g-1 for the xylose isomerase strain, the xylose isomerase strain achieved higher ethanol yield on consumed sugars, 0.41 g g-1 compared with 0.32 g g-1 for the xylose reductase/xylitol dehydrogenase strain. Anaerobic fermentation of a mixture of glucose, arabinose and xylose resulted in higher final ethanol concentration, 14.7 g l-1 for the xylose reductase/xylitol dehydrogenase strain compared with 11.8 g l-1 for the xylose isomerase strain, and in higher specific ethanol productivity, 0.024 g (g cells-1 h-1 compared with 0.01 g (g cells-1 h-1

  13. Genetic analysis of D-xylose metabolism by endophytic yeast strains of Rhodotorula graminis and Rhodotorula mucilaginosa

    Directory of Open Access Journals (Sweden)

    Ping Xu

    2011-01-01

    Full Text Available Two novel endophytic yeast strains, WP1 and PTD3, isolated from within the stems of poplar (Populus trees, were genetically characterized with respect to their xylose metabolism genes. These two strains, belonging to the species Rhodotorula graminis and R. mucilaginosa, respectively, utilize both hexose and pentose sugars, including the common plant pentose sugar, D-xylose. The xylose reductase (XYL1 and xylitol dehydrogenase (XYL2 genes were cloned and characterized. The derived amino acid sequences of xylose reductase (XR and xylose dehydrogenase (XDH were 32%~41% homologous to those of Pichia stipitis and Candida. spp., two species known to utilize xylose. The derived XR and XDH sequences of WP1 and PTD3 had higher homology (73% and 69% identity with each other. WP1 and PTD3 were grown in single sugar and mixed sugar media to analyze the XYL1 and XYL2 gene regulation mechanisms. Our results revealed that for both strains, the gene expression is induced by D-xylose, and that in PTD3 the expression was not repressed by glucose in the presence of xylose.

  14. Inhibition of spore germination of Alternaria tenuis by sulfur dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Couey, H.M.

    1962-08-01

    As a part of a continuing study of SO/sub 2/ fumigation of table grapes, the effect of SO/sub 2/ on spores of an isolate of A. tenuis Auct. causing decay of table grapes was determined. The amount of SO/sub 2/ required to inhibit completely spore germination depended on availability of moisture and the temperature. At 20/sup 0/C, wet spores required 20-min exposure to 100 ppm SO/sub 2/ to prevent germination, but spores equilibrated at 90% relative humidity (RH) required 10-min exposure to 1000 ppm SO/sub 2/. Dry spores at 60% RH were unaffected by a 20-min exposure to 4000 ppm SO/sub 2/. Increasing the temperature in the range 5-20/sup 0/C increased effectiveness of the SO/sub 2/ treatment. A comparison of Alternaria with Botrytis cinerea Fr. (studied earlier) showed that wet spores of these organisms were about equally sensitive to SO/sub 2/, but that dry Alternaria spores were more resistant to SO/sub 2/ than dry Botrytis spores under comparable conditions.

  15. Pilot-scale steam explosion for xylose production from oil palm empty fruit bunches and the use of xylose for ethanol production.

    Science.gov (United States)

    Duangwang, Sairudee; Ruengpeerakul, Taweesak; Cheirsilp, Benjamas; Yamsaengsung, Ram; Sangwichien, Chayanoot

    2016-03-01

    Pilot-scale steam explosion equipments were designed and constructed, to experimentally solubilize xylose from oil palm empty fruit bunches (OPEFB) and also to enhance an enzyme accessibility of the residual cellulose pulp. The OPEFB was chemically pretreated prior to steam explosion at saturated steam (SS) and superheated steam (SHS) conditions. The acid pretreated OPEFB gave the highest xylose recovery of 87.58 ± 0.21 g/kg dried OPEFB in the liquid fraction after explosion at SHS condition. These conditions also gave the residual cellulose pulp with high enzymatic accessibility of 73.54 ± 0.41%, which is approximately threefold that of untreated OPEFB. This study has shown that the acid pretreatment prior to SHS explosion is an effective method to enhance both xylose extraction and enzyme accessibility of the exploded OPEFB. Moreover, the xylose solution obtained in this manner could directly be fermented by Candida shehatae TISTR 5843 giving high ethanol yield of 0.30 ± 0.08 g/g xylose. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Adaptation of a lead-tolerant population of Agrostis tenuis to low soil fertility

    Energy Technology Data Exchange (ETDEWEB)

    Jowett, D

    1959-07-04

    A population of Agrostis tenuis growing on lead ore grindings at Goginan was found to be tolerant of lead. The pasture populations responded to calcium and phosphate, whereas the lead mine population showed no response to calcium and a lesser response to phosphate. The lead mine population data was included. A considerable range of adaption to soil mineral levels has now been found in this species. It has populations tolerant of lead, copper, and nickel poisoning, and of low levels of calcium and phosphate. In lead mine habitats A tenuis is not replaced by A. canina as in more normal habitats. A tenuis is subject to the most extreme conditions of low fertility. 4 tables.

  17. Parameters oprimization for xylitol production by Candida tropicalis ...

    African Journals Online (AJOL)

    Ashraf

    2011-11-02

    Nov 2, 2011 ... Micro-determination of xylose in plasma. Analyst. 100. (1186): 12-15. Uhari M, Kontiokari Niemela T, Novel MA (1998). Use of xylitol sugar in preventing acute otitis media. Pediastrics, 102: 879-884. Vongsuvanlert V, Tani Y (1989). Xylitol production by methanol yeast. Candida boidinii (klocckera Sp) No.

  18. Diversity and physiological characterization of D-xylose-fermenting yeasts isolated from the Brazilian Amazonian Forest.

    Science.gov (United States)

    Cadete, Raquel M; Melo, Monaliza A; Dussán, Kelly J; Rodrigues, Rita C L B; Silva, Silvio S; Zilli, Jerri E; Vital, Marcos J S; Gomes, Fátima C O; Lachance, Marc-André; Rosa, Carlos A

    2012-01-01

    This study is the first to investigate the Brazilian Amazonian Forest to identify new D-xylose-fermenting yeasts that might potentially be used in the production of ethanol from sugarcane bagasse hemicellulosic hydrolysates. A total of 224 yeast strains were isolated from rotting wood samples collected in two Amazonian forest reserve sites. These samples were cultured in yeast nitrogen base (YNB)-D-xylose or YNB-xylan media. Candida tropicalis, Asterotremella humicola, Candida boidinii and Debaryomyces hansenii were the most frequently isolated yeasts. Among D-xylose-fermenting yeasts, six strains of Spathaspora passalidarum, two of Scheffersomyces stipitis, and representatives of five new species were identified. The new species included Candida amazonensis of the Scheffersomyces clade and Spathaspora sp. 1, Spathaspora sp. 2, Spathaspora sp. 3, and Candida sp. 1 of the Spathaspora clade. In fermentation assays using D-xylose (50 g/L) culture medium, S. passalidarum strains showed the highest ethanol yields (0.31 g/g to 0.37 g/g) and productivities (0.62 g/L · h to 0.75 g/L · h). Candida amazonensis exhibited a virtually complete D-xylose consumption and the highest xylitol yields (0.55 g/g to 0.59 g/g), with concentrations up to 25.2 g/L. The new Spathaspora species produced ethanol and/or xylitol in different concentrations as the main fermentation products. In sugarcane bagasse hemicellulosic fermentation assays, S. stipitis UFMG-XMD-15.2 generated the highest ethanol yield (0.34 g/g) and productivity (0.2 g/L · h), while the new species Spathaspora sp. 1 UFMG-XMD-16.2 and Spathaspora sp. 2 UFMG-XMD-23.2 were very good xylitol producers. This study demonstrates the promise of using new D-xylose-fermenting yeast strains from the Brazilian Amazonian Forest for ethanol or xylitol production from sugarcane bagasse hemicellulosic hydrolysates.

  19. Candida auris

    Science.gov (United States)

    ... Testing Treatment & Outcomes Health Professionals Statistics More Resources Candidiasis Candida infections of the mouth, throat, and esophagus Vaginal candidiasis Invasive candidiasis Definition Symptoms Risk & Prevention Sources Diagnosis ...

  20. Expression and Characterisation of Recombinant Rhodocyclus tenuis High Potential Iron-Sulphur Protein

    DEFF Research Database (Denmark)

    Caspersen, Michael Bjerg; Bennet, K.; Christensen, Hans Erik Mølager

    2000-01-01

    The high potential iron-sulfur protein (HiPIP) from Rhodocyclus tenuis strain 2761 has been overproduced in Escherichia coli from its structural gene, purified to apparent homogeneity, and then characterized by an array of methods. UV-visible spectra of the reduced and oxidized recombinant protein...

  1. Breeding system and bumblebee drone pollination of an explosively pollen-releasing plant, Meliosma tenuis (Sabiaceae).

    Science.gov (United States)

    Wong Sato, A A; Kato, M

    2018-05-01

    Explosive pollen release is a mechanism used by some angiosperms that serves to attach pollen to a pollinator's body. It is usually adopted by species with zygomorphic tubular flowers and pollinated by birds and bees. The tree genus Meliosma (Sabiaceae, Proteales) has unique disc-like flowers that are externally actinomorphic, but internally zygomorphic, and release pollen explosively. To elucidate the adaptive significance of explosive pollen release, we observed flowering behaviour, the breeding system and pollinator visits to flowers of the Japanese species Meliosma tenuis in a temperate forest. Flowers bloomed in June and were nectariferous and protandrous. Explosive pollen release was triggered by slight tactile stimuli to anther filaments or staminodes in male-stage flowers. Because pollen cannot come into contact with the pistils enclosed by staminodes, M. tenuis is functionally protandrous. Artificial pollination treatments revealed that M. tenuis is allogamous. The dominant flower visitors were nectar-seeking drones of the bumblebee species Bombus ardens (Apidae). The drones' behaviour, pollen attachment on their bodies and fruit set of visit-restricted flowers suggest that they are the only agent triggering the explosive pollen release mechanism, and are the main pollinator of M. tenuis. The finding that bumblebee workers rarely visit these flowers suggests that the explosive pollen release has another function, namely to discourage pollen-harvesting bumblebee workers. © 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

  2. Effect of temperature on the growth rate of Griffithsia tenuis c. agardh (Rhodophyta: ceramiales)

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, W.W.; Casterlin, M.E.

    1977-01-01

    Clonal cultures of Griffithsia tenuis were grown for 18 days (Erdschreiber solution, LD 12 : 12, 2200 lux) at 13, 18, 22 and 25/sup 0/C. The optimum temperature for growth (increase in number of cells) under these conditions was 22/sup 0/C.

  3. Stage-Related Defense Response Induction in Tomato Plants by Nesidiocoris tenuis

    Science.gov (United States)

    Naselli, Mario; Urbaneja, Alberto; Siscaro, Gaetano; Jaques, Josep A.; Zappalà, Lucia; Flors, Víctor; Pérez-Hedo, Meritxell

    2016-01-01

    The beneficial effects of direct predation by zoophytophagous biological control agents (BCAs), such as the mirid bug Nesidiocoris tenuis, are well-known. However, the benefits of zoophytophagous BCAs’ relation with host plants, via induction of plant defensive responses, have not been investigated until recently. To date, only the females of certain zoophytophagous BCAs have been demonstrated to induce defensive plant responses in tomato plants. The aim of this work was to determine whether nymphs, adult females, and adult males of N. tenuis are able to induce defense responses in tomato plants. Compared to undamaged tomato plants (i.e., not exposed to the mirid), plants on which young or mature nymphs, or adult males or females of N. tenuis fed and developed were less attractive to the whitefly Bemisia tabaci, but were more attractive to the parasitoid Encarsia formosa. Female-exposed plants were more repellent to B. tabaci and more attractive to E. formosa than were male-exposed plants. When comparing young- and mature-nymph-exposed plants, the same level of repellence was obtained for B. tabaci, but mature-nymph-exposed plants were more attractive to E. formosa. The repellent effect is attributed to the signaling pathway of abscisic acid, which is upregulated in N. tenuis-exposed plants, whereas the parasitoid attraction was attributed to the activation of the jasmonic acid signaling pathway. Our results demonstrate that all motile stages of N. tenuis can trigger defensive responses in tomato plants, although these responses may be slightly different depending on the stage considered. PMID:27472328

  4. Screening and characterizing of xylanolytic and xylose-fermenting yeasts isolated from the wood-feeding termite, Reticulitermes chinensis.

    Directory of Open Access Journals (Sweden)

    Sameh Samir Ali

    Full Text Available The effective fermentation of xylose remains an intractable challenge in bioethanol industry. The relevant xylanase enzyme is also in a high demand from industry for several biotechnological applications that inevitably in recent times led to many efforts for screening some novel microorganisms for better xylanase production and fermentation performance. Recently, it seems that wood-feeding termites can truly be considered as highly efficient natural bioreactors. The highly specialized gut systems of such insects are not yet fully realized, particularly, in xylose fermentation and xylanase production to advance industrial bioethanol technology as well as industrial applications of xylanases. A total of 92 strains from 18 yeast species were successfully isolated and identified from the gut of wood-feeding termite, Reticulitermes chinensis. Of these yeasts and strains, seven were identified for new species: Candida gotoi, Candida pseudorhagii, Hamamotoa lignophila, Meyerozyma guilliermondii, Sugiyamaella sp.1, Sugiyamaella sp. 2, and Sugiyamaella sp.3. Based on the phylogenetic and phenotypic characterization, the type strain of C. pseudorhagii sp. nov., which was originally designated strain SSA-1542T, was the most frequently occurred yeast from termite gut samples, showed the highly xylanolytic activity as well as D-xylose fermentation. The highest xylanase activity was recorded as 1.73 and 0.98 U/mL with xylan or D-xylose substrate, respectively, from SSA-1542T. Among xylanase-producing yeasts, four novel species were identified as D-xylose-fermenting yeasts, where the yeast, C. pseudorhagii SSA-1542T, showed the highest ethanol yield (0.31 g/g, ethanol productivity (0.31 g/L·h, and its fermentation efficiency (60.7% in 48 h. Clearly, the symbiotic yeasts isolated from termite guts have demonstrated a competitive capability to produce xylanase and ferment xylose, suggesting that the wood-feeding termite gut is a promising reservoir for novel

  5. Optimization of fed-batch fermentation for xylitol production by Candida tropicalis.

    Science.gov (United States)

    Kim, J-H; Han, K-C; Koh, Y-H; Ryu, Y-W; Seo, J-H

    2002-07-01

    Xylitol, a functional sweetener, was produced from xylose by biological conversion using Candida tropicalis ATCC 13803. Based on a two-substrate fermentation using glucose for cell growth and xylose for xylitol production, fed-batch fermentations were undertaken to increase the final xylitol concentration. The effects of xylose and xylitol on xylitol production rate were studied to determine the optimum concentrations for fed-batch fermentation. Xylose concentration in the medium (100 g l(-1)) and less than 200 g l(-1) total xylose plus xylitol concentration were determined as optimum for maximum xylitol production rate and xylitol yield. Increasing the concentrations of xylose and xylitol decreased the rate and yield of xylitol production and the specific cell growth rate, probably because of an increase in osmotic stress that would interfere with xylose transport, xylitol flux to secretion to cell metabolism. The feeding rate of xylose solution during the fed-batch mode of operation was determined by using the mass balance equations and kinetic parameters involved in the equations in order to increase final xylitol concentration without affecting xylitol and productivity. The optimized fed-batch fermentation resulted in 187 g l(-1) xylitol concentration, 0.75 g xylitol g xylose(-1) xylitol yield and 3.9 g xylitol l(-1) h(-1) volumetric productivity.

  6. Anaerobic xylose fermentation by Spathaspora passalidarum

    DEFF Research Database (Denmark)

    Hou, Xiaoru

    2012-01-01

    A cost-effective conversion of lignocellulosic biomass into bioethanol requires that the xylose released from the hemicellulose fraction (20–40% of biomass) can be fermented. Baker’s yeast, Saccharomyces cerevisiae, efficiently ferments glucose but it lacks the ability to ferment xylose. Xylose-fermenting...... yeast such as Pichia stipitis requires accurately controlled microaerophilic conditions during the xylose fermentation, rendering the process technically difficult and expensive. In this study, it is demonstrated that under anaerobic conditions Spathaspora passalidarum showed high ethanol production...

  7. Potential of xylose-fermented yeast isolated from sugarcane bagasse waste for xylitol production using hydrolysate as carbon source

    Directory of Open Access Journals (Sweden)

    Kusumawadee Thancharoen

    2016-10-01

    Full Text Available Xylitol is a high value sugar alcohol that is used as a sweetener. In the past years, the biological process of D-xylose from lignocellulosic material into xylitol has gained increasing interest as an alternative production method. In this study, sugarcane bagasse was used as raw material for xylitol production because of its high efficiency, reduced industrial cost, and high concentration of xylose. Pre-treatment of sugarcane bagasse with sulfuric acid was performed with various conditions. The results showed that the optimum condition was exhibited for 3.1% sulfuric acid at 126°C for 18 min producing 19 g/l xylose. Isolated yeasts from the sugarcane bagasse were selected and tested for xylitol ability from xylose. Results showed that Candida tropicalis KS 10-3 (from 72 isolates had the highest ability and produced 0.47 g xylitol/ g xylose in 96 hrs of cultivation containing 32.30 g/l xylose was used as the production medium.

  8. Xylitol from rice husks by acid hydrolysis and Candida yeast fermentation

    Directory of Open Access Journals (Sweden)

    Magale K. D. Rambo

    2013-01-01

    Full Text Available An investigation was conducted into the production of xylose by acid hydrolysis of rice husks and its subsequent bioconversion to xylitol. The parameters were optimised using the response surface methodology. The fermentation stage took place with the aid of the yeast species Candida guilliermondii and Candida tropicalis. An evaluation of the influence of several biomass pre-treatments was also performed. The effects of the acid concentration and hydrolysate pH on xylitol global yield were also assessed, and the highest yield of xylitol was 64.0% (w/w. The main products, xylose and xylitol, were identified and quantified by means of liquid chromatography.

  9. Huperzine A production by Paecilomyces tenuis YS-13, an endophytic fungus isolated from Huperzia serrata.

    Science.gov (United States)

    Su, Jingqian; Yang, Minhe

    2015-01-01

    Huperzine A (HupA), a naturally occurring alkaloid in the plant family Huperziaceae, has drawn great interest for its potential application in Alzheimer disease therapy. Our primary objective was to identify alkaloid- and HupA-producing fungi from the Chinese folk herb, Huperzia serrata. We established a rapid and efficient model for screening HupA-producing endophytic fungal strains. The presence of HupA in Paecilomyces tenuis YS-13 was analysed by thin-layer chromatography, high-performance liquid chromatography and mass spectrometry. The fermentation yield of HupA was 21.0 μg/L, and the IC50 of the crude extract of YS-13 fermentation broth was 1.27 ± 0.04 mg/mL. This is the first report of P. tenuis as a HupA-producing endophyte isolated from Huperziaceae.

  10. Effects of NADH-preferring xylose reductase expression on ethanol production from xylose in xylose-metabolizing recombinant Saccharomyces cerevisiae.

    Science.gov (United States)

    Lee, Sung-Haeng; Kodaki, Tsutomu; Park, Yong-Cheol; Seo, Jin-Ho

    2012-04-30

    Efficient conversion of xylose to ethanol is an essential factor for commercialization of lignocellulosic ethanol. To minimize production of xylitol, a major by-product in xylose metabolism and concomitantly improve ethanol production, Saccharomyces cerevisiae D452-2 was engineered to overexpress NADH-preferable xylose reductase mutant (XR(MUT)) and NAD⁺-dependent xylitol dehydrogenase (XDH) from Pichia stipitis and endogenous xylulokinase (XK). In vitro enzyme assay confirmed the functional expression of XR(MUT), XDH and XK in recombinant S. cerevisiae strains. The change of wild type XR to XR(MUT) along with XK overexpression led to reduction of xylitol accumulation in microaerobic culture. More modulation of the xylose metabolism including overexpression of XR(MUT) and transaldolase, and disruption of the chromosomal ALD6 gene encoding aldehyde dehydrogenase (SX6(MUT)) improved the performance of ethanol production from xylose remarkably. Finally, oxygen-limited fermentation of S. cerevisiae SX6(MUT) resulted in 0.64 g l⁻¹ h⁻¹ xylose consumption rate, 0.25 g l⁻¹ h⁻¹ ethanol productivity and 39% ethanol yield based on the xylose consumed, which were 1.8, 4.2 and 2.2 times higher than the corresponding values of recombinant S. cerevisiae expressing XR(MUT), XDH and XK only. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Lotus tenuis Seedling Establishment and Biomass Production in Flooding Pampa Grasslands (Buenos Aires , Argentina Establecimiento de Plántulas y Producción de Biomasa de Lotus tenuis en Pastizales de la Pampa Deprimida (Buenos Aires, Argentina

    Directory of Open Access Journals (Sweden)

    Osvaldo R Vignolio

    2011-03-01

    Full Text Available Biomass and plant density of Lotus tenuis Waldst. & Kit. ex Willd. have been reported in decreasing in grasslands and pastures. Our objective was to determine if L. tenuis biomass and plant density can be increased in grassland through seed addition. Two separated experiments under cattle grazing exclusion were conducted in three paddocks of a Flooding Pampa grassland. The first experiment was from autumn 2004 to autumn 2006 and the second from autumn 2005 to autumn 2007. Different L. tenuis seed additions (0, 57, 229, 917 and 1833 seeds m-² were broadcast into experimental plots. In the second experiment, besides seed additions there was a reseeding of approximately 900 seed m-² from seed rain produced by plants of grassland. Seed density explained the 81% and 19% of the variation in seedling density and L. tenuis biomass, respectively. Seedling emergence occurred mainly between autumn and early spring, while seedling mortality was mainly between late spring and early summer. Lotus tenuis adult plant density and biomass production increased with seed additions. Total biomass production in the plant community varied between 589.94 ± 26.89 and 1042.44 ± 54.39 g m-² yr-1 and the differences were principally attributed to precipitations. Lotus tenuis biomass contribution was of approximately 10%. The results suggest that L. tenuis seedling and plant establishment and biomass production can be increased through seed addition and/or seed rain through grazing exclusion during reproductive period.En pastizales y pasturas ha sido documentada la reducción de la densidad de plantas y de la biomasa de Lotus tenuis Waldst. & Kit. ex Willd. Nuestro objetivo fue determinar si su densidad de plantas y su producción de biomasa pueden ser incrementadas en un pastizal mediante la adición de semillas. Dos experimentos sin pastoreo fueron realizados en tres potreros de un pastizal de la Pampa Deprimida. El primer experimento fue realizado entre otoño 2004

  12. Temperature Dependence of Respiration in Larvae and Adult Colonies of the Corals Acropora tenuis and Pocillopora damicornis

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    Dwi Haryanti

    2015-06-01

    Full Text Available Although algal symbionts can become a source of reactive oxygen species under stressful conditions, symbiotic planulae of the coral Pocillopora damicornis are highly tolerant to thermal stress compared with non-symbiotic planulae of Acropora tenuis. As a first step to understand how P. damicornis planulae attain high stress tolerance, we compared the respiration rate and temperature dependence between symbiotic planulae of P. damicornis and non-symbiotic planulae of A. tenuis, as well as between larvae and adult branches within each species. Larvae and adult branches of both species had similar temperature dependency of respiration rate, with the temperature coefficient (Q10 values of about 2. Planula larvae of P. damicornis had a significantly lower respiration rate than that of A. tenuis larvae at 25–30 °C, but not at 32 °C, whereas adult branches of P. damicornis had a significantly higher respiration rate than that of A. tenuis branches at all temperatures. Thus, P. damicornis larvae appear to be capable of reducing their respiration rate to a greater extent than A. tenuis larvae, which could partly explain why P. damicornis larvae had high survivorship under thermal stress, although other antioxidant or photoprotective mechanisms should be investigated in the future.

  13. Comparison of the xylose reductase-xylitol dehydrogenase and the xylose isomerase pathways for xylose fermentation by recombinant Saccharomyces cerevisiae

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    Hahn-Hägerdal Bärbel

    2007-02-01

    Full Text Available Abstract Background Two heterologous pathways have been used to construct recombinant xylose-fermenting Saccharomyces cerevisiae strains: i the xylose reductase (XR and xylitol dehydrogenase (XDH pathway and ii the xylose isomerase (XI pathway. In the present study, the Pichia stipitis XR-XDH pathway and the Piromyces XI pathway were compared in an isogenic strain background, using a laboratory host strain with genetic modifications known to improve xylose fermentation (overexpressed xylulokinase, overexpressed non-oxidative pentose phosphate pathway and deletion of the aldose reductase gene GRE3. The two isogenic strains and the industrial xylose-fermenting strain TMB 3400 were studied regarding their xylose fermentation capacity in defined mineral medium and in undetoxified lignocellulosic hydrolysate. Results In defined mineral medium, the xylose consumption rate, the specific ethanol productivity, and the final ethanol concentration were significantly higher in the XR- and XDH-carrying strain, whereas the highest ethanol yield was achieved with the strain carrying XI. While the laboratory strains only fermented a minor fraction of glucose in the undetoxified lignocellulose hydrolysate, the industrial strain TMB 3400 fermented nearly all the sugar available. Xylitol was formed by the XR-XDH-carrying strains only in mineral medium, whereas in lignocellulose hydrolysate no xylitol formation was detected. Conclusion Despite by-product formation, the XR-XDH xylose utilization pathway resulted in faster ethanol production than using the best presently reported XI pathway in the strain background investigated. The need for robust industrial yeast strains for fermentation of undetoxified spruce hydrolysates was also confirmed.

  14. Genomic analysis of a xylose operon and characterization of novel xylose isomerase and xylulokinase from Bacillus coagulans NL01.

    Science.gov (United States)

    Zheng, Zhaojuan; Lin, Xi; Jiang, Ting; Ye, Weihua; Ouyang, Jia

    2016-08-01

    To investigate the xylose operon and properties of xylose isomerase and xylulokinase in Bacillus coagulans that can effectively ferment xylose to lactic acid. The xylose operon is widely present in B. coagulans. It is composed of four putative ORFs. Novel xylA and xylB from B. coagulans NL01 were cloned and expressed in Escherichia coli. Sequence of xylose isomerase was more conserved than that of xylulokinase. Both the enzymes exhibited maximum activities at pH 7-8 but with a high temperature maximum of 80-85 °C, divalent metal ion was prerequisite for their activation. Xylose isomerase and xylulokinase were most effectively activated by Ni(2+) and Co(2+), respectively. Genomic analysis of xylose operon has contributed to understanding xylose metabolism in B. coagulans and the novel xylose isomerase and xylulokinase might provide new alternatives for metabolic engineering of other strains to improve their fermentation performance on xylose.

  15. Glucose (xylose) isomerase production from thermotolerant and ...

    African Journals Online (AJOL)

    Owner

    2012-11-13

    Nov 13, 2012 ... in the production of the high fructose corn syrup (HFCS) from corn starch. ... Key words: Glucose isomerase, xylose isomerase, enzyme activity, Klebsiella, ... Soil, water, and manure (five samples each) were collected from.

  16. Grateloupia tenuis Wang et Luan sp. nov. (Halymeniaceae, Rhodophyta: A New Species from South China Sea Based on Morphological Observation and rbcL Gene Sequences Analysis

    Directory of Open Access Journals (Sweden)

    Ling Yu

    2013-01-01

    Full Text Available Grateloupia tenuis Wang et Luan sp. nov. is a new species described from Lingshui, Hainan Province, South China Sea. Based on the external form and internal structure, combined with rbcL gene sequence analysis, Grateloupia tenuis is distinct from other Grateloupia species as follows: (1 thalli is slippery and cartilaginous in texture; possess fewer branches, relatively slight main axes, and two or three dichotomous branches; (2 cortex is 5-6 layers; medulla is solid when young, but hollow in old branches; reproductive structures are dispersed in main axes of thalli and lower portions of branchlets; exhibits Grateloupia-type auxiliary cell ampullae; (3 the four studied G. tenuis sequences were positioned in a large Grateloupia clade of Halymeniaceae, which included sister group generitype G. filicina with 68 bp differences; G. tenuis was determined to be a sister taxon to the G. catenata, G. ramosissima, G. orientalis, and G. filiformis subclade. The pairwise distances between G. tenuis and these species were 39 to 50 bp. The sequences of G. tenuis differed by 81–108 bp from the sequences of other samples in Grateloupia; there are 114–133 bp changes between G. tenuis and other genera of Halymeniaceae. In final analysis, we considered Grateloupia tenuis Wang et Luan sp. nov. to be a new species of genus Grateloupia.

  17. Grateloupia tenuis Wang et Luan sp. nov. (Halymeniaceae, Rhodophyta): a new species from South China Sea based on morphological observation and rbcL gene sequences analysis.

    Science.gov (United States)

    Yu, Ling; Wang, Hongwei; Luan, Rixiao

    2013-01-01

    Grateloupia tenuis Wang et Luan sp. nov. is a new species described from Lingshui, Hainan Province, South China Sea. Based on the external form and internal structure, combined with rbcL gene sequence analysis, Grateloupia tenuis is distinct from other Grateloupia species as follows: (1) thalli is slippery and cartilaginous in texture; possess fewer branches, relatively slight main axes, and two or three dichotomous branches; (2) cortex is 5-6 layers; medulla is solid when young, but hollow in old branches; reproductive structures are dispersed in main axes of thalli and lower portions of branchlets; exhibits Grateloupia-type auxiliary cell ampullae; (3) the four studied G. tenuis sequences were positioned in a large Grateloupia clade of Halymeniaceae, which included sister group generitype G. filicina with 68 bp differences; G. tenuis was determined to be a sister taxon to the G. catenata, G. ramosissima, G. orientalis, and G. filiformis subclade. The pairwise distances between G. tenuis and these species were 39 to 50 bp. The sequences of G. tenuis differed by 81-108 bp from the sequences of other samples in Grateloupia; there are 114-133 bp changes between G. tenuis and other genera of Halymeniaceae. In final analysis, we considered Grateloupia tenuis Wang et Luan sp. nov. to be a new species of genus Grateloupia.

  18. Grateloupia tenuis Wang et Luan sp. nov. (Halymeniaceae, Rhodophyta): A New Species from South China Sea Based on Morphological Observation and rbcL Gene Sequences Analysis

    Science.gov (United States)

    Wang, Hongwei; Luan, Rixiao

    2013-01-01

    Grateloupia tenuis Wang et Luan sp. nov. is a new species described from Lingshui, Hainan Province, South China Sea. Based on the external form and internal structure, combined with rbcL gene sequence analysis, Grateloupia tenuis is distinct from other Grateloupia species as follows: (1) thalli is slippery and cartilaginous in texture; possess fewer branches, relatively slight main axes, and two or three dichotomous branches; (2) cortex is 5-6 layers; medulla is solid when young, but hollow in old branches; reproductive structures are dispersed in main axes of thalli and lower portions of branchlets; exhibits Grateloupia-type auxiliary cell ampullae; (3) the four studied G. tenuis sequences were positioned in a large Grateloupia clade of Halymeniaceae, which included sister group generitype G. filicina with 68 bp differences; G. tenuis was determined to be a sister taxon to the G. catenata, G. ramosissima, G. orientalis, and G. filiformis subclade. The pairwise distances between G. tenuis and these species were 39 to 50 bp. The sequences of G. tenuis differed by 81–108 bp from the sequences of other samples in Grateloupia; there are 114–133 bp changes between G. tenuis and other genera of Halymeniaceae. In final analysis, we considered Grateloupia tenuis Wang et Luan sp. nov. to be a new species of genus Grateloupia. PMID:24455703

  19. Xylose fermentation to ethanol. A review

    Energy Technology Data Exchange (ETDEWEB)

    McMillan, J D

    1993-01-01

    The past several years have seen tremendous progress in the understanding of xylose metabolism and in the identification, characterization, and development of strains with improved xylose fermentation characteristics. A survey of the numerous microorganisms capable of directly fermenting xylose to ethanol indicates that wild-type yeast and recombinant bacteria offer the best overall performance in terms of high yield, final ethanol concentration, and volumetric productivity. The best performing bacteria, yeast, and fungi can achieve yields greater than 0.4 g/g and final ethanol concentrations approaching 5%. Productivities remain low for most yeast and particularly for fungi, but volumetric productivities exceeding 1.0 g/L-h have been reported for xylose-fermenting bacteria. In terms of wild-type microorganisms, strains of the yeast Pichia stipitis show the most promise in the short term for direct high-yield fermentation of xylose without byproduct formation. Of the recombinant xylose-fermenting microorganisms developed, recombinant E. coli ATTC 11303 (pLOI297) exhibits the most favorable performance characteristics reported to date.

  20. Overview of Catalytic Properties of Fungal Xylose Reductases and Molecular Engineering Approaches for Improved Xylose Utilisation in Yeast

    Directory of Open Access Journals (Sweden)

    Sk Amir Hossain

    2018-03-01

    Full Text Available Background and Objective: Xylose reductases belong to the aldo-keto reductase family of enzymes, which catalyse the conversion of xylose to xylitol. Yeast xylose reductases have been intensively studied in the last two decades due to their significance in biotechnological production of ethanol and xylitol from xylose. Due to its GRAS status and pronounced tolerance to harsh conditions, Saccharomyces cerevisiae is the ideal organism for industrial production of both xylitol and ethanol. However, Saccharomyces cerevisiae is unable to use xylose as the sole carbon source due to the lack of xylose specific transporters and insufficient activity of metabolic pathways for xylose utilisation. The aim of this paper is to give an overview of attempts in increasing biotechnological potential of xylose reductases and to highlight the prospective of this application. Results and Conclusion: In order to create strains with improved xylose utilization, different approaches were attempted including simultaneous overexpression of xylitol dehydrogenase, xylose reductase and pentose phosphate pathway enzymes, heterologous expression of putative xylose transporters or heterologous expression of genes coding for enzymes included in the xylose metabolism, respectively. Furthermore, number of attempts to genetically modify different xylose reductases is increasing. This review presents current knowledge about yeast xylose reductases and the different approaches applied in order to improve xylose metabolism in yeast.Conflict of interest: The authors declare no conflict of interest.

  1. Development of Efficient Xylose Fermentation in Saccharomyces cerevisiae : Xylose Isomerase as a Key Component

    NARCIS (Netherlands)

    Van Maris, A.J.A.; Winkler, A.A.; Kuyper, M.; De Laat, W.T.; Van Dijken, J.P.; Pronk, J.T.

    2007-01-01

    Metabolic engineering of Saccharomyces cerevisiae for ethanol production from d-xylose, an abundant sugar in plant biomass hydrolysates, has been pursued vigorously for the past 15 years. Whereas wild-type S. cerevisiae cannot ferment d-xylose, the ketoisomer d-xylulose can be metabolised slowly.

  2. Improved bioethanol production using fusants of Saccharomyces cerevisiae and xylose-fermenting yeasts.

    Science.gov (United States)

    Kumari, Rajni; Pramanik, K

    2012-06-01

    The present research deals with the development of a hybrid yeast strain with the aim of converting pentose and hexose sugar components of lignocellulosic substrate to bioethanol by fermentation. Different fusant strains were obtained by fusing protoplasts of Saccharomyces cerevisiae and xylose-fermenting yeasts such as Pachysolen tannophilus, Candida shehatae and Pichia stipitis. The fusants were sorted by fluorescent-activated cell sorter and further confirmed by molecular characterization. The fusants were evaluated by fermentation of glucose-xylose mixture and the highest ethanol producing fusant was used for further study to ferment hydrolysates produced by acid pretreatment and enzymatic hydrolysis of cotton gin waste. Among the various fusant and parental strains used under present study, RPR39 was found to be stable and most efficient strain giving maximum ethanol concentration (76.8 ± 0.31 g L(-1)), ethanol productivity (1.06 g L(-1) h(-1)) and ethanol yield (0.458 g g(-1)) by fermentation of glucose-xylose mixture under test conditions. The fusant has also shown encouraging result in fermenting hydrolysates of cotton gin waste with ethanol concentration of 7.08 ± 0.142 g L(-1), ethanol yield of 0.44 g g(-1), productivity of 0.45 g L(-1) h(-1) and biomass yield of 0.40 g g(-1).

  3. Directed evolution of xylose isomerase for improved xylose catabolism and fermentation in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Lee, Sun-Mi; Jellison, Taylor; Alper, Hal S

    2012-08-01

    The heterologous expression of a highly functional xylose isomerase pathway in Saccharomyces cerevisiae would have significant advantages for ethanol yield, since the pathway bypasses cofactor requirements found in the traditionally used oxidoreductase pathways. However, nearly all reported xylose isomerase-based pathways in S. cerevisiae suffer from poor ethanol productivity, low xylose consumption rates, and poor cell growth compared with an oxidoreductase pathway and, additionally, often require adaptive strain evolution. Here, we report on the directed evolution of the Piromyces sp. xylose isomerase (encoded by xylA) for use in yeast. After three rounds of mutagenesis and growth-based screening, we isolated a variant containing six mutations (E15D, E114G, E129D, T142S, A177T, and V433I) that exhibited a 77% increase in enzymatic activity. When expressed in a minimally engineered yeast host containing a gre3 knockout and tal1 and XKS1 overexpression, the strain expressing this mutant enzyme improved its aerobic growth rate by 61-fold and both ethanol production and xylose consumption rates by nearly 8-fold. Moreover, the mutant enzyme enabled ethanol production by these yeasts under oxygen-limited fermentation conditions, unlike the wild-type enzyme. Under microaerobic conditions, the ethanol production rates of the strain expressing the mutant xylose isomerase were considerably higher than previously reported values for yeast harboring a xylose isomerase pathway and were also comparable to those of the strains harboring an oxidoreductase pathway. Consequently, this study shows the potential to evolve a xylose isomerase pathway for more efficient xylose utilization.

  4. Molecular characterization of a gene for aldose reductase (CbXYL1) from Candida boidinii and its expression in Saccharomyces cerevisiae

    Science.gov (United States)

    Min Hyung Kang; Haiying Ni; Thomas W. Jeffries

    2003-01-01

    Candida boidinii produces significant amounts of xylitol from xylose, and assays of crude homogenates for aldose (xylose) reductase (XYL1p) have been reported to show relatively high activity with NADH as a cofactor even though XYL1p purified from this yeast does not have such activity. A gene coding for XYL1p from C. boidinii (CbXYL1) was isolated by amplifying the...

  5. Stoichiometric network constraints on xylose metabolism by recombinant Saccharomyces cerevisiae

    Science.gov (United States)

    Yong-Su Jin; Thomas W. Jeffries

    2004-01-01

    Metabolic pathway engineering is constrained by the thermodynamic and stoichiometric feasibility of enzymatic activities of introduced genes. Engineering of xylose metabolism in Saccharomyces cerevisiae has focused on introducing genes for the initial xylose assimilation steps from Pichia stipitis, a xylose-fermenting yeast, into S. cerevisiae, a yeast raditionally...

  6. Saccharomyces cerevisiae engineered for xylose metabolism exhibits a respiratory response

    Science.gov (United States)

    Yong-Su Jin; Jose M. Laplaza; Thomas W. Jeffries

    2004-01-01

    Native strains of Saccharomyces cerevisiae do not assimilate xylose. S. cerevisiae engineered for D-xylose utilization through the heterologous expression of genes for aldose reductase ( XYL1), xylitol dehydrogenase (XYL2), and D-xylulokinase ( XYL3 or XKS1) produce only limited amounts of ethanol in xylose medium. In recombinant S. cerevisiae expressing XYL1, XYL2,...

  7. Metabolic control analysis of xylose catabolism in Aspergillus

    NARCIS (Netherlands)

    Prathumpai, W.; Gabelgaard, J.B.; Wanchanthuek, P.; Vondervoort, van de P.J.I.; Groot, de M.J.L.; McIntyre, M.; Nielsen, J.

    2003-01-01

    A kinetic model for xylose catabolism in Aspergillus is proposed. From a thermodynamic analysis it was found that the intermediate xylitol will accumulate during xylose catabolism. Use of the kinetic model allowed metabolic control analysis (MCA) of the xylose catabolic pathway to be carried out,

  8. Phytochemical screening, antioxidant and cytotoxic activity of fruit extracts of Calamus tenuis Roxb

    Directory of Open Access Journals (Sweden)

    Zaki Uddin Ahmed

    2014-08-01

    Full Text Available Objective: To investigate the antioxidant and cytotoxic activity of the fruits of Calamus tenuis Roxb. Methods: The preliminary phytochemical group tests were done, which revealed the presence of alkaloid, tannin, flavonoid and steroid. The dried fruit was extracted in soxhlet apparatus using petroleum ether, ethyl acetate and methanol. Antioxidant potential of each extract was evaluated using total phenol content, total flavonoid content, cupric reducing antioxidant capacity, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, and total antioxidant capacity determinations. Results: The extracts were found to possess moderate to high amounts of phenolic and flavonoid contents. In cupric reducing antioxidant capacity assay the extracts showed moderate reducing power which increases with concentration. Scavenging of 1,1-diphenyl-2-picrylhydrazyl radical was found to rise with concentration with lowest IC50 value for methanol extract, which was confirmed by total antioxidant activity test that shows highest (95 mg/g of extract in ascorbic acid equivalent for methanol extract. In Brine shrimp lethality bioassay the methanol and petroleum ether extracts were found to be toxic to Brine shrimp nauplii, with LC50 of 25.53 µg/mL and 28.07 µg/mL respectively while the LC50 of the reference vincristine sulphate was 1.32 µg/mL. Ethyl acetate extract was found to be moderately cytotoxic showing LC50 of 47.79 µg/mL. Conclusions: The results of the present study suggest that the fruits of Calamus tenuis Roxb possess antioxidant and cytotoxic potential. Moreover, phytochemical screening reveals the presence of alkaloid, tannin, flavonoid and steroid, which may be responsible for the observed bioactivities.

  9. Candida infective endocarditis

    NARCIS (Netherlands)

    Baddley, J. W.; Benjamin, D. K.; Patel, M.; Miró, J.; Athan, E.; Barsic, B.; Bouza, E.; Clara, L.; Elliott, T.; Kanafani, Z.; Klein, J.; Lerakis, S.; Levine, D.; Spelman, D.; Rubinstein, E.; Tornos, P.; Morris, A. J.; Pappas, P.; Fowler, V. G.; Chu, V. H.; Cabell, C.; DraGordon, David; Devi, Uma; Spelman, Denis; van der Meer, Jan T. M.; Kauffman, Carol; Bradley, Suzanne; Armstrong, William; Giannitsioti, Efthymia; Giamarellou, Helen; Lerakis, Stamatios; del Rio, Ana; Moreno, Asuncio; Mestres, Carlos A.; Pare, Carlos; Garcia de la Maria, Cristina; de Lazzario, Elisa; Marco, Francesc; Gatell, Jose M.; Miro, Jose M.; Almela, Manel; Azqueta, Manuel; Jimenez-Exposito, Maria Jesus; de Benito, Natividad; Perez, Noel; Almirante, Benito; Fernandez-Hidalgo, Nuria; de Vera, Pablo Rodriguez; Tornos, Pilar; Falco, Vicente

    2008-01-01

    Candida infective endocarditis (IE) is uncommon but often fatal. Most epidemiologic data are derived from small case series or case reports. This study was conducted to explore the epidemiology, treatment patterns, and outcomes of patients with Candida IE. We compared 33 Candida IE cases to 2,716

  10. Effect of mineral nutrients on cell growth and self-flocculation of Tolypothrix tenuis for the production of a biofertilizer.

    Science.gov (United States)

    Silva, P G; Silva, H J

    2007-02-01

    The influence of mineral nutrients on the growth and self-flocculation of Tolypothrix tenuis was studied. The identification of possible limiting nutrients in the culture medium was performed by the biomass elemental composition approach. A factorial experimental design was used in order to estimate the contribution of macronutrients and micronutrients, as well as their interactions. Iron was identified to be limiting in the culture medium. The micronutrients influenced mainly cellular growth without effects on self-flocculation. Conversely, the self-flocculation capacity of the biomass increased at higher concentrations of macronutrients. The optimization of mineral nutrition of T. tenuis allowed a 73% increase in the final biomass level and 3.5 times higher flocculation rates.

  11. Thermochemistry of α-D-xylose(cr)

    International Nuclear Information System (INIS)

    Ribeiro da Silva, Manuel A.V.; Ribeiro da Silva, Maria D.M.C.; Lobo Ferreira, Ana I.M.C.; Shi, Quan; Woodfield, Brian F.; Goldberg, Robert N.

    2013-01-01

    Highlights: ► Well-characterized material. ► Oxygen bomb calorimetry. ► Heat capacities obtained by using a Physical Property Measurement System. ► Thermochemical Network Calculations. ► Accurate thermodynamic property values of a key biochemical substance. -- Abstract: The thermochemistry of α-D-xylose(cr) was studied by means of oxygen bomb calorimetry and a Physical Property Measurement System (PPMS) in zero magnetic field. The sample of α-D-xylose(cr) used in this study was one well-characterized by HPLC, Karl Fischer analysis, NMR, and by carbon dioxide analysis. The standard molar enthalpy of combustion was found to be Δ c H m o = −(2342.2 ± 0.8) kJ·mol −1 at T = 298.15 K and at the standard pressure p° = 0.1 MPa. The standard molar heat capacity for α-D-xylose(cr) was measured with the PPMS over the temperature range 1.9001 ⩽ T/K ⩽ 303.66. At T = 298.15 K, C p,m o = (178.1 ± 1.8) J·K −1 ·mol −1 . The values of C p,m o were fit as a function of T by using theoretical and empirical models for appropriate temperature ranges. The results of these fits were used to calculate values of C p,m o , the entropy increment Δ 0 T S m o , Δ 0 T H m o , and Φ m o =(Δ 0 T S m o -Δ 0 T H m o /T) from T = 0.5 K to T = 300 K. Derived quantities for α-D-xylose(cr) are the standard molar enthalpy of formation Δ f H m o = −(1054.5 ± 1.1) kJ·mol −1 , the third law standard molar entropy S m o = (175.3 ± 1.9) J·K −1 ·mol −1 , and the standard molar Gibbs energy of formation Δ f G m o = −(750.5 ± 1.0) kJ·mol −1 . A comparison of values of Δ c H m o and S m o for the five-carbon aldoses demonstrated a striking similarity in the values of these respective properties for α-D-xylose(cr), D-ribose(cr), and D-arabinose(cr). Thermochemical network calculations were performed that led to values of the standard formation properties at T = 298.15 K for a variety of biochemical substances: D-xylose(aq), D-xylose − (aq), D-xylose 2

  12. Heavy metal tolerance in populations of Agrostis tenuis Sibth and other grasses

    Energy Technology Data Exchange (ETDEWEB)

    Gregory, R P.G.; Bradshaw, A D

    1965-01-01

    Populations of Agrostis tenuis can be found growing on a variety of different mine workings in conditions of metal contamination toxic to most higher plants. Samples of such populations together with samples of populations taken from ordinary pastures were tested for tolerance to high concentrations of copper, nickel, lead and zinc by measuring the effect of these metals on the rooting of tillers. The soils in which the populations were originally growing were analyzed for each of the four metals and the tolerances of the populations have been related to the levels of the metals in the soils. In general, the mine populations show remarkable tolerance to the particular metals present in high quantities in the soils of their original habitats: the pasture populations do not show this tolerance. The tolerance is specific, for, except in the case of zinc and nickel, tolerance to one metal is not accompanied by tolerance to any other. There must, therefore, be three specific tolerances in the one species. Individual tolerances can however occur together and this can be related to the occurrence of the two metals together in toxic quantities in the soil. The tolerances must be genetically controlled but the physiological mechanism involved is not clear. A number of other species were also shown to have populations tolerant to high levels of zinc. 27 references, 7 figures, 6 tables.

  13. Ethanol production by recombinant and natural xylose-utilising yeasts

    Energy Technology Data Exchange (ETDEWEB)

    Eliasson, Anna

    2000-07-01

    The xylose-fermenting capacity of recombinant Saccharomyces cerevisiae carrying XYL1 and XYL2 from Pichia stipitis, which encode xylose reductase (XR) and xylitol dehydrogenase (XDH), respectively, is poor due to high xylitol formation. Whereas, P. stipitis exhibits high ethanol yield on xylose, the tolerance towards inhibitors in the lignocellulosic hydrolysate is low. A recombinant strain possessing the advantageous characteristics of both S. cerevisiae and P. stipitis would constitute a biocatalyst capable of efficient ethanol production from lignocellulosic hydrolysate. In the work presented in this thesis, factors influencing xylose fermentation in recombinant S. cerevisiae and in the natural xylose-fermenting yeast P. stipitis have been identified and investigated. Anaerobic xylulose fermentation was compared in strains of Zygosaccharomyces and S. cerevisiae, mutants and wild-type strains to identify host strain background and genetic modifications beneficial for xylose fermentation. The greatest positive effect was found for over-expression of the gene XKS1 for the pentose phosphate pathway (PPP) enzyme xylulokinase (XK), which increased the ethanol yield by almost 85%. The Zygosaccharomyces strains tested formed large amounts of polyols, making them unsuitable as host strains. The XR/XDH/XK ratio was found to determine whether carbon accumulated in a xylitol pool or was further utilised for ethanol production in recombinant xylose-utilising S. cerevisiae. Simulations, based on a kinetic model, and anaerobic xylose cultivation experiments implied that a 1:{>=}10:{>=}4 relation was optimal in minimising xylitol formation. Ethanol formation increased with decreasing XR/XDH ratio, whereas xylitol formation decreased and XK overexpression was necessary for adequate ethanol formation. Based on the knowledge of optimal enzyme ratios, a stable, xylose-utilising strain, S. cerevisiae TMB 3001, was constructed by chromosomal integration of the XYL1 and XYL2 genes

  14. Enhanced isoprenoid production from xylose by engineered Saccharomyces cerevisiae.

    Science.gov (United States)

    Kwak, Suryang; Kim, Soo Rin; Xu, Haiqing; Zhang, Guo-Chang; Lane, Stephan; Kim, Heejin; Jin, Yong-Su

    2017-11-01

    Saccharomyces cerevisiae has limited capabilities for producing fuels and chemicals derived from acetyl-CoA, such as isoprenoids, due to a rigid flux partition toward ethanol during glucose metabolism. Despite numerous efforts, xylose fermentation by engineered yeast harboring heterologous xylose metabolic pathways was not as efficient as glucose fermentation for producing ethanol. Therefore, we hypothesized that xylose metabolism by engineered yeast might be a better fit for producing non-ethanol metabolites. We indeed found that engineered S. cerevisiae on xylose showed higher expression levels of the enzymes involved in ethanol assimilation and cytosolic acetyl-CoA synthesis than on glucose. When genetic perturbations necessary for overproducing squalene and amorphadiene were introduced into engineered S. cerevisiae capable of fermenting xylose, we observed higher titers and yields of isoprenoids under xylose than glucose conditions. Specifically, co-overexpression of a truncated HMG1 (tHMG1) and ERG10 led to substantially higher squalene accumulation under xylose than glucose conditions. In contrast to glucose utilization producing massive amounts of ethanol regardless of aeration, xylose utilization allowed much less amounts of ethanol accumulation, indicating ethanol is simultaneously re-assimilated with xylose consumption and utilized for the biosynthesis of cytosolic acetyl-CoA. In addition, xylose utilization by engineered yeast with overexpression of tHMG1, ERG10, and ADS coding for amorphadiene synthase, and the down-regulation of ERG9 resulted in enhanced amorphadiene production as compared to glucose utilization. These results suggest that the problem of the rigid flux partition toward ethanol production in yeast during the production of isoprenoids and other acetyl-CoA derived chemicals can be bypassed by using xylose instead of glucose as a carbon source. Biotechnol. Bioeng. 2017;114: 2581-2591. © 2017 Wiley Periodicals, Inc. © 2017 Wiley

  15. Nutritional implications of D-xylose in pigs

    NARCIS (Netherlands)

    Schutte, J.B.; Jong, J.de; Polziehn, R.; Verstegen, M.W.A.

    1991-01-01

    Hemicellulose consists primarily of pentose sugars, joined together in a polysaccharide chain with D-xylose as the most abundant component. Ileal digestibility and urinary excretion of D-xylose and associated effects of this pentose sugar on ileal and faecal digestibility of dry matter (DM), organic

  16. Ethanol production in fermentation of mixed sugars containing xylose

    Science.gov (United States)

    Viitanen, Paul V [West Chester, PA; Mc Cutchen, Carol M [Wilmington, DE; Li,; Xu, [Newark, DE; Emptage, Mark [Wilmington, DE; Caimi, Perry G [Kennett Square, PA; Zhang, Min [Lakewood, CO; Chou, Yat-Chen [Lakewood, CO; Franden, Mary Ann [Centennial, CO

    2009-12-08

    Xylose-utilizing Z. mobilis strains were found to have improved ethanol production when grown in medium containing mixed sugars including xylose if sorbitol or mannitol was included in the medium. The effect was seen in concentrations of mixed sugars where no growth lag period occurs, as well as in higher sugars concentrations.

  17. Alcohol Fermentation and Biomass formation from xylose, glucose ...

    African Journals Online (AJOL)

    Cerevisiae (LB-7) was the slowest in growth and utilization of xylose into biomass (economic conversion coefficient of 0.03), while K3 showed fastest utilization of xylose (coefficient 0.76). For the production of ethanol, the fastest growth and assimilation of glucose was recorded by Pa. tannophilus (P1) (coefficient 0.56) ...

  18. Distribution of zinc-65 in Agrostis tenuis Sibth. and A. stolonifera L. tissues

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, P J

    1969-11-01

    The distribution of /sup 65/Zn in zinc-tolerant and copper-tolerant plants of Agrotis spp. from toxic mine-tailings in England and Wales was compared with zinc distribution in non-tolerant plants. Isotope was applied in culture solution in which the plants were growing. No differences could be demonstrated between the plants by whole-plant radioautography, or by zinc analyses of the tops. Root/shoot ratios calculated from specific activity values varied with population, the non-tolerant plants having the lowest and the zinc-tolerant plants the highest ratio. After solvent (80% ethanol and water) extractions, the root residue of zinc-tolerant plants contained a higher percentage of /sup 65/Zn than that of non-tolerant plants. Chemical fractionation of the roots revealed that the main difference was that the amount of /sup 65/Zn in the pectate extract of the cell wall was high in zinc-tolerant plants and low in non-tolerant plants. The /sup 65/Zn distribution in the copper-tolerant plants was similar to that in the non-tolerant plants, indicating that the tolerance mechanisms for the two elements are different. Soluble protein and RNA preparations were made but they contained low levels of /sup 65/Zn. An exception was the relatively high value for RNA from zinc-tolerant A. stolonifera shoots. An anionic complex of /sup 65/Zn in the soluble fraction was investigated. This complex accounted for most of the radioactivity in A. tenuis extracts of shoots but the concentration of the complex was low in A. stolonifera shoots, and in root extracts of all plants examined. 18 references, 2 figures, 4 tables.

  19. The effect of the herbicide glyphosate on non-target spiders: Part I. Direct effects on Lepthyphantes tenuis under laboratory conditions.

    Science.gov (United States)

    Haughton, A J; Bell, J R; Wilcox, A; Boatman, N D

    2001-11-01

    We examined the toxic effects of glyphosate to adult female Lepthyphantes tenuis (Araneae, Linyphiidae), a common spider of agricultural habitats. The overspray technique was used to investigate the effect of the herbicide on forty individuals in each of six glyphosate treatments (2160, 1440, 1080, 720, 360 and 180 g ha-1) and a distilled water control. Spiders collected from the wild were individually placed in exposure chambers and checked every 24 h over a 72-h experimental period. Mortality of L tenuis remained at less than 10% in all treatments at 24 and 48 h after spray application, and only increased marginally (to 13%) after 72 h. These results support other limited data which suggest that glyphosate is 'harmless' to non-target arthropods. More extended laboratory testing to investigate any side-effects of glyphosate on the life history of L tenuis and other non-beneficial invertebrates is required.

  20. Candida ethanolica n. sp.

    Science.gov (United States)

    Rybárová, J; Stros, F; Kocková-Kratochvílová, A

    1980-01-01

    A new yeast, Candida ethanolica, isolated from industrial fodder yeast cultivated on synthetic ethanol as the only source of carbon, originally designated III-5 and III-6, is described. This species differs from all recently accepted Candida species in not assimilating nitrate, not producing urease and not fermenting sugars.

  1. Xylitol production by Candida parapsilosis under fed-batch culture

    Directory of Open Access Journals (Sweden)

    Sandra A. Furlan

    2001-06-01

    Full Text Available Xylitol production by Candida parapsilosis was investigated under fed-batch cultivation, using single (xylose or mixed (xylose and glucose sugars as substrates. The presence of glucose in the medium induced the production of ethanol as secondary metabolite and improved specific rates of growth, xylitol formation and substrate consumption. Fractionated supply of the feed medium at constant sugar concentration did not promote any increase on the productivity compared to the single batch cultivation.A produção de xylitol por Candida parapsilosis foi investigada em regime de batelada alimentada, usando substratos açucarados de composição simples (xilose ou composta (xilose e glicose. A presença de glicose no meio induziu a formação de etanol como metabólito secundário. A suplementação fracionada do meio de alimentação numa concentração fixa de açúcar não resultou em aumento da produtividade em relação àquela alcançada em batelada simples.

  2. Changing flux of xylose metabolites by altering expression of xylose reductase and xylitol dehydrogenase in recombinant Saccharomyces cerevisiae

    Science.gov (United States)

    Yong-Su Jin; Thomas W. Jeffries

    2003-01-01

    We changed the fluxes of xylose metabolites in recombinant Saccharomyces cerevisiae by manipulating expression of Pichia stipitis genes(XYL1 and XYL2) coding for xylose reductase (XR) and xylitol dehydrogenase (XDH), respectively. XYL1 copy number was kept constant by integrating it into the chromosome. Copy numbers of XYL2 were varied either by integrating XYL2 into...

  3. Multidrug-Resistant Candida

    DEFF Research Database (Denmark)

    Arendrup, Maiken Cavling; Patterson, Thomas F

    2017-01-01

    Invasive Candida infections remain an important cause of morbidity and mortality, especially in hospitalized and immunocompromised or critically ill patients. A limited number of antifungal agents from only a few drug classes are available to treat patients with these serious infections. Resistance...... can be either intrinsic or acquired. Resistance mechanisms are not exchanged between Candida; thus, acquired resistance either emerges in response to an antifungal selection pressure in the individual patient or, more rarely, occur due to horizontal transmission of resistant strains between patients....... Although multidrug resistance is uncommon, increasing reports of multidrug resistance to the azoles, echinocandins, and polyenes have occurred in several Candida species, most notably Candida glabrata and more recently Candida auris. Drivers are overall antifungal use, subtherapeutic drug levels at sites...

  4. Temperature as an ecological factor in the distribution of two closely related freshwater Triclads: an experimental study. [Polycelis tenuis, polycelis nigra

    Energy Technology Data Exchange (ETDEWEB)

    Lascombe, C.; Pattee, E.; Bornard, C.

    1975-01-01

    The influence of temperature on the ecophysiology of two closely related limnophilic Triclads, Polycelis tenuis and P. nigra, in the Lyons region was investigated. Both species have the same physiological rate in the middle zone of the temperature range, but P. tenuis prevails at both ends of the range. It tolerates higher temperatures and its reproduction rate is greater in the cold. Also, because of the existence of physiological races, it seems adapted to a greater diversity of situations. It appears as a real eurytherm. These different points contribute to the explanation of the habitat of both species in the region.

  5. Application of gamma rays for increasing the productivity of xylitol from rice straw by candida teleprocess and candida guilieliermondii

    International Nuclear Information System (INIS)

    Abouzeid, A.A.; El-zawahry, Y.A.; El-mongy, T.M.; El-Fouly, M.Z.; Abd El-aziz, A.B.

    2005-01-01

    Irradiating the rice straw with high dose level of gamma rays (100-KGy) after being treated with diluted sulphuric acid increased the xylitol yields from the hydrolysates to 43.2 and 45.0 g/l out of 63.0 g/l xylose by Candida tropical and Candida guilliermondii, respectively. Meanwhile, irradiating C. tropical is and C. guilliermondii with low dose levels (0.25 and 0.5 KGy, respectively) before being inoculated in artificial medium, containing 150 g/l xylose, increased the yields of xylitol by the irradiated species. On the contrary, the produced xylitol was decreased sharply in case of isolates irradiated with 1 KGy especially C. tropical is, which showed less resistance to gamma rays recording. D 1 0, value 1.225 compared with 1.608 for C. guilliermondii. Sub-lethal dose of gamma rays (10 and 8 KGy) shrank C. guilliermondii cells and their sh,ape became irregular while C. tropical is cells formed small cottony fibres structure on the external surface of the cell wall, respectively. Meanwhile, lethal radiation doses-(l l and 9 KGy) caused deformation of the vegetative cells of both isolates. Many cells were enlarged, the cell walls of many others were ruptured and the internal contents were released outside the cells. Complete lyses of some cells-was also observed

  6. Heterologous expression of Spathaspora passalidarum xylose reductase and xylitol dehydrogenase genes improved xylose fermentation ability of Aureobasidium pullulans.

    Science.gov (United States)

    Guo, Jian; Huang, Siyao; Chen, Yefu; Guo, Xuewu; Xiao, Dongguang

    2018-04-30

    Aureobasidium pullulans is a yeast-like fungus that can ferment xylose to generate high-value-added products, such as pullulan, heavy oil, and melanin. The combinatorial expression of two xylose reductase (XR) genes and two xylitol dehydrogenase (XDH) genes from Spathaspora passalidarum and the heterologous expression of the Piromyces sp. xylose isomerase (XI) gene were induced in A. pullulans to increase the consumption capability of A. pullulans on xylose. The overexpression of XYL1.2 (encoding XR) and XYL2.2 (encoding XDH) was the most beneficial for xylose utilization, resulting in a 17.76% increase in consumed xylose compared with the parent strain, whereas the introduction of the Piromyces sp. XI pathway failed to enhance xylose utilization efficiency. Mutants with superior xylose fermentation performance exhibited increased intracellular reducing equivalents. The fermentation performance of all recombinant strains was not affected when glucose or sucrose was utilized as the carbon source. The strain with overexpression of XYL1.2 and XYL2.2 exhibited excellent fermentation performance with mimicked hydrolysate, and pullulan production increased by 97.72% compared with that of the parent strain. The present work indicates that the P4 mutant (using the XR/XDH pathway) with overexpressed XYL1.2 and XYL2.2 exhibited the best xylose fermentation performance. The P4 strain showed the highest intracellular reducing equivalents and XR and XDH activity, with consequently improved pullulan productivity and reduced melanin production. This valuable development in aerobic fermentation by the P4 strain may provide guidance for the biotransformation of xylose to high-value products by A. pullulans through genetic approach.

  7. Improvement of biotechnological xylitol production by glucose during cultive of Candida guilliermondii in sugarcane bagasse hydrolysate

    Directory of Open Access Journals (Sweden)

    Débora Danielle Virgínio da Silva

    2007-03-01

    Full Text Available The effect of glucose on xylose-to-xylitol bioconversion by Candida guilliermondii was examined by adding it to sugarcane bagasse hydrolysate medium to obtain different glucose:xylose ratios (1:25, 1:12, 1:5 and 1:2.5. Under experimental conditions, increasing glucose:xylose ratio improved the assimilation of the xylose present in the hydrolysate by yeast, resulting in biomass increase, and in the formation of xylitol and glycerol/ethanol by-products. Maximum values of xylitol yield (0.59 g g-1 and volumetric productivity (0.53 g l-1.h-1 were obtained with glucose:xylose ratio of 1:5, resulting in the higher conversion efficiency (64.3%.O efeito da glicose na bioconversão de xilose em xilitol por Candida guilliermondii foi avaliado em hidrolisado hemicelulósico de bagaço de cana com diferentes relações glicose:xilose (1:25, 1:12, 1:5 and 1:2,5. Sob as condições experimentais, o aumento da relação glicose:xilose favoreceu a assimilação da xilose presente no hidrolisado, resultando em aumento da biomassa celular e aumento da formação de xilitol e dos sub-produtos glicerol e etanol. Os valores máximos do fator de conversão de xilose em xilitol (0,59 g g-1 e da produtividade volumétrica de xilitol (0,53 g l-1.h-1 foram obtidos com a relação glicose:xilose 1:5, resultando na maior eficiência de conversão (64,3%.

  8. Single zymomonas mobilis strain for xylose and arabinose fermentation

    Science.gov (United States)

    Zhang, Min; Chou, Yat-Chen; Picataggio, Stephen K.; Finkelstein, Mark

    1998-01-01

    This invention relates to single microorganisms which normally do not ferment pentose sugars which are genetically altered to ferment the pentose sugars, xylose and arabinose, to produce ethanol, and a fermentation process utilizing the same. Examples include Zymomonas mobilis which has been transformed with a combination of E. coli genes for xylose isomerase, xylulokinase, L-arabinose isomerase, L-ribulokinase, L-ribulose 5-phosphate 4-epimerase, transaldolase and transketolase. Expression of added genes are under the control of Z. mobilis promoters. These newly created microorganisms are useful for fermenting glucose, xylose and arabinose, produced by hydrolysis of hemicellulose and cellulose or starch, to produce ethanol.

  9. External development of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae in the subterranean termite Heterotermes tenuis Desenvolvimento dos fungos entomopatogênicos Beauveria bassiana E Metarhizium anisopliae no cupim subterrâneo Heterotermes tenuis

    Directory of Open Access Journals (Sweden)

    Alcides Moino Jr.

    2002-06-01

    Full Text Available The subterranean termite Heterotermes tenuis is one of the main pests of sugarcane and eucalyptus in Brazil, and the use of entomopathogenic fungi, alone or associated to chemicals, is an efficient and environmentally favorable method for its control. Studies related to the fungal development on these insects are important due to the effect of insect behavior on entomopathogens. The objective of this work was to describe the external development of Beauveria bassiana and Metarhizium anisopliae on H. tenuis using Scanning Electron Microscopy (SEM, determining the duration of the different phases of fungal infection. Two fixation techniques for preparing SEM samples were also evaluated. Worker specimens of H. tenuis were inoculated with a 1 x 10(9 conidia mL-1 suspension of the fungi and maintained at 25±1ºC and 70±10% relative humidity. Insects were collected from 0 to 144 hours after inoculation and prepared on SEM stubs for each of the two fixation techniques. The results obtained with the two techniques were compared and duration of the different phases of the infection process were estimated from SEM observations and compared for three fungal isolates. B. bassiana and M. anisopliae have similar development cycles on the termite, but some important differences exist. The penetration, colonization and conidiogenesis phases are relatively faster for M. anisopliae than for B. bassiana, which results in a faster rate of insect mortality. The fixation technique with OsO4 vapor is suitable for preparation of insects to be used in SEM observation of the developmental stages of entomopathogenic fungi.O cupim subterrâneo Heterotermes tenuis , uma das principais pragas da cana-de-açúcar e eucalipto no Brasil, e o uso de fungos entomopatogênicos, isoladamente ou associados a produtos químicos, é um método eficiente e ambientalmente seguro para seu controle. Estudos relacionados ao desenvolvimento fúngico nestes insetos são importantes devido

  10. Pnp gene modification for improved xylose utilization in Zymomonas

    Science.gov (United States)

    Caimi, Perry G G; Qi, Min; Tao, Luan; Viitanen, Paul V; Yang, Jianjun

    2014-12-16

    The endogenous pnp gene encoding polynucleotide phosphorylase in the Zymomonas genome was identified as a target for modification to provide improved xylose utilizing cells for ethanol production. The cells are in addition genetically modified to have increased expression of ribose-5-phosphate isomerase (RPI) activity, as compared to cells without this genetic modification, and are not limited in xylose isomerase activity in the absence of the pnp modification.

  11. Effects of coal contamination on early life history processes of a reef-building coral, Acropora tenuis.

    Science.gov (United States)

    Berry, Kathryn L E; Hoogenboom, Mia O; Brinkman, Diane L; Burns, Kathryn A; Negri, Andrew P

    2017-01-15

    Successful reproduction and larval dispersal are important for the persistence of marine invertebrate populations, and these early life history processes can be sensitive to marine pollution. Coal is emerging as a contaminant of interest due to the proximity of ports and shipping lanes to coral reefs. To assess the potential hazard of this contaminant, gametes, newly developed embryos, larvae and juveniles of the coral Acropora tenuis were exposed to a range of coal leachate, suspended coal, and coal smothering treatments. Fertilisation was the most sensitive reproductive process tested. Embryo survivorship decreased with increasing suspended coal concentrations and exposure duration, effects on larval settlement varied between treatments, while effects on juvenile survivorship were minimal. Leachate exposures had negligible effects on fertilisation and larval settlement. These results indicate that coral recruitment could be affected by spills that produce plumes of suspended coal particles which interact with gametes and embryos soon after spawning. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. Candida infection of the skin

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000880.htm Candida infection of the skin To use the sharing features on this page, please enable JavaScript. Candida infection of the skin is a yeast infection ...

  13. Thrush and Other Candida Infections

    Science.gov (United States)

    ... Text Size Email Print Share Thrush and Other Candida Infections Page Content Article Body The fungus Candida is normally found on and in the body ... tract and genital area. Most of the time, Candida does not cause any symptoms. When these organisms ...

  14. Bacterial xylose isomerases from the mammal gut Bacteroidetes cluster function in Saccharomyces cerevisiae for effective xylose fermentation.

    Science.gov (United States)

    Peng, Bingyin; Huang, Shuangcheng; Liu, Tingting; Geng, Anli

    2015-05-17

    Xylose isomerase (XI) catalyzes the conversion of xylose to xylulose, which is the key step for anaerobic ethanolic fermentation of xylose. Very few bacterial XIs can function actively in Saccharomyces cerevisiae. Here, we illustrate a group of XIs that would function for xylose fermentation in S. cerevisiae through phylogenetic analysis, recombinant yeast strain construction, and xylose fermentation. Phylogenetic analysis of deposited XI sequences showed that XI evolutionary relationship was highly consistent with the bacterial taxonomic orders and quite a few functional XIs in S. cerevisiae were clustered with XIs from mammal gut Bacteroidetes group. An XI from Bacteroides valgutus in this cluster was actively expressed in S. cerevisiae with an activity comparable to the fungal XI from Piromyces sp. Two XI genes were isolated from the environmental metagenome and they were clustered with XIs from environmental Bacteroidetes group. These two XIs could not be expressed in yeast with activity. With the XI from B. valgutus expressed in S. cerevisiae, background yeast strains were optimized by pentose metabolizing pathway enhancement and adaptive evolution in xylose medium. Afterwards, more XIs from the mammal gut Bacteroidetes group, including those from B. vulgatus, Tannerella sp. 6_1_58FAA_CT1, Paraprevotella xylaniphila and Alistipes sp. HGB5, were individually transformed into S. cerevisiae. The known functional XI from Orpinomyces sp. ukk1, a mammal gut fungus, was used as the control. All the resulting recombinant yeast strains were able to ferment xylose. The respiration-deficient strains harboring B. vulgatus and Alistipes sp. HGB5 XI genes respectively obtained specific xylose consumption rate of 0.662 and 0.704 g xylose gcdw(-1) h(-1), and ethanol specific productivity of 0.277 and 0.283 g ethanol gcdw(-1) h(-1), much comparable to those obtained by the control strain carrying Orpinomyces sp. ukk1 XI gene. This study demonstrated that XIs clustered in the

  15. Microaerobic conversion of xylose to ethanol in recombinant Saccharomyces cerevisiae SX6(MUT) expressing cofactor-balanced xylose metabolic enzymes and deficient in ALD6.

    Science.gov (United States)

    Jo, Sung-Eun; Seong, Yeong-Je; Lee, Hyun-Soo; Lee, Soo Min; Kim, Soo-Jung; Park, Kyungmoon; Park, Yong-Cheol

    2016-06-10

    Xylose is a major monosugar in cellulosic biomass and should be utilized for cost-effective ethanol production. In this study, xylose-converting ability of recombinant Saccharomyces cerevisiae SX6(MUT) expressing NADH-preferring xylose reductase mutant (R276H) and other xylose-metabolic enzymes, and deficient in aldehyde dehydrogenase 6 (Ald6p) were characterized at microaerobic conditions using various sugar mixtures. The reduction of air supply from 0.5vvm to 0.1vvm increased specific ethanol production rate by 75% and did not affect specific xylose consumption rate. In batch fermentations using various concentrations of xylose (50-104g/L), higher xylose concentration enhanced xylose consumption rate and ethanol productivity but reduced ethanol yield, owing to the accumulation of xylitol and glycerol from xylose. SX6(MUT) consumed monosugars in pitch pine hydrolysates and produced 23.1g/L ethanol from 58.7g/L sugars with 0.39g/g ethanol yield, which was 14% higher than the host strain of S. cerevisiae D452-2 without the xylose assimilating enzymes. In conclusion, S. cerevisiae SX6(MUT) was characterized to possess high xylose-consuming ability in microaerobic conditions and a potential for ethanol production from cellulosic biomass. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Xylose fermentation efficiency and inhibitor tolerance of the recombinant industrial Saccharomyces cerevisiae strain NAPX37.

    Science.gov (United States)

    Li, Yun-Cheng; Mitsumasu, Kanako; Gou, Zi-Xi; Gou, Min; Tang, Yue-Qin; Li, Guo-Ying; Wu, Xiao-Lei; Akamatsu, Takashi; Taguchi, Hisataka; Kida, Kenji

    2016-02-01

    Industrial yeast strains with good xylose fermentation ability and inhibitor tolerance are important for economical lignocellulosic bioethanol production. The flocculating industrial Saccharomyces cerevisiae strain NAPX37, harboring the xylose reductase-xylitol dehydrogenase (XR-XDH)-based xylose metabolic pathway, displayed efficient xylose fermentation during batch and continuous fermentation. During batch fermentation, the xylose consumption rates at the first 36 h were similar (1.37 g/L/h) when the initial xylose concentrations were 50 and 75 g/L, indicating that xylose fermentation was not inhibited even when the xylose concentration was as high as 75 g/L. The presence of glucose, at concentrations of up to 25 g/L, did not affect xylose consumption rate at the first 36 h. Strain NAPX37 showed stable xylose fermentation capacity during continuous ethanol fermentation using xylose as the sole sugar, for almost 1 year. Fermentation remained stable at a dilution rate of 0.05/h, even though the xylose concentration in the feed was as high as 100 g/L. Aeration rate, xylose concentration, and MgSO4 concentration were found to affect xylose consumption and ethanol yield. When the xylose concentration in the feed was 75 g/L, a high xylose consumption rate of 6.62 g/L/h and an ethanol yield of 0.394 were achieved under an aeration rate of 0.1 vvm, dilution rate of 0.1/h, and 5 mM MgSO4. In addition, strain NAPX37 exhibited good tolerance to inhibitors such as weak acids, furans, and phenolics during xylose fermentation. These findings indicate that strain NAPX37 is a promising candidate for application in the industrial production of lignocellulosic bioethanol.

  17. Lactic acid production from xylose by Geobacillus stearothermophilus strain 15

    Science.gov (United States)

    Kunasundari, B.; Naresh, S.; Chu, J. E.

    2017-09-01

    Lactic acid is an important compound with a wide range of industrial applications. The present study tested the efficiency of xylose, as a sole carbon source to be converted to lactic acid by Geobacillus stearothermophilus strain 15. To the best of our knowledge, limited information is available on the directed fermentation of xylose to lactic acid by this bacterium. The effects of different parameters such as temperature, pH, incubation time, agitation speed, concentrations of nitrogen and carbon sources on the lactic acid production were investigated statistically. It was found that the bacterium exhibited poor assimilation of xylose to lactic acid. Temperature, agitation rate and incubation time were determined to improve the lactic acid production slightly. The highest lactic acid yield obtained was 8.9% at 45°C, 300 RPM, 96 h, pH of 6.0 with carbon and nitrogen source concentrations were fixed at 5% w/v.

  18. Signature pathway expression of xylose utilization in the genetically engineered industrial yeast Saccharomyces cerevisiae

    Science.gov (United States)

    Background: The limited xylose utilizing ability of native Saccharomyces cerevisiae has been a major obstacle for efficient cellulosic ethanol production from lignocellulosic materials. Haploid laboratory strains of S. cerevisiae are commonly used for genetic engineering to enable its xylose utiliza...

  19. Co-fermentation of glucose, xylose and/or cellobiose by yeast

    Science.gov (United States)

    Jeffries, Thomas W.; Willis, Laura B.; Long, Tanya M.; Su, Yi-Kai

    2013-09-10

    Provided herein are methods of using yeast cells to produce ethanol by contacting a mixture comprising xylose with a Spathaspora yeast cell under conditions suitable to allow the yeast to ferment at least a portion of the xylose to ethanol. The methods allow for efficient ethanol production from hydrolysates derived from lignocellulosic material and sugar mixtures including at least xylose and glucose or xylose, glucose and cellobiose.

  20. Transposon mutagenesis to improve the growth of recombinant Saccharomyces cerevisiae on D-xylose

    Science.gov (United States)

    Haiying Ni; Jose M. Laplaza; Thomas W. Jeffries

    2007-01-01

    Saccharomyces cerevisiae L2612 transformed with genes for xylose reductase and xylitol dehydrogenase (XYL1 and XYL2) grows well on glucose but very poorly on D-xylose. When a gene for D-xylulokinase (XYL3 or XKS1) is overexpressed, growth on glucose is unaffected, but growth on xylose is blocked. Spontaneous or chemically induced mutants of this engineered yeast that...

  1. Engineering of carbon catabolite repression in recombinant xylose fermenting Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Roca, Christophe Francois Aime; Haack, Martin Brian; Olsson, Lisbeth

    2004-01-01

    analysed for changes in xylose consumption rate and ethanol production rate during anaerobic batch and chemostat cultivations on a mixture of 20 g l(-1) glucose and 50 g l(-1) xylose, and their characteristics were compared to the parental strain S. cerevisiae TMB3001 (XYL1, XYL2, XKS1). Improvement...... that xylose is a repressive sugar for S. cerevisiae....

  2. Construction of efficient xylose utilizing Pichia pastoris for industrial enzyme production.

    Science.gov (United States)

    Li, Pengfei; Sun, Hongbing; Chen, Zao; Li, Yin; Zhu, Taicheng

    2015-02-21

    Cellulosic biomass especially agricultural/wood residues can be utilized as feedstock to cost-effectively produce fuels, chemicals and bulk industrial enzymes, which demands xylose utilization from microbial cell factories. While previous works have made significant progress in improving microbial conversion of xylose into fuels and chemicals, no study has reported the engineering of efficient xylose utilizing protein expression systems for the purpose of producing industrial enzymes. In this work, using Pichia pastoris as an example, we demonstrated the successful engineering of xylose metabolizing ability into of protein expression systems. A heterologous XI (xylose isomerase) pathway was introduced into P. pastoris GS115 by overexpressing the Orpinomyces spp. XI or/and the endogenous XK (xylulokinase) gene, and evolutionary engineering strategies were also applied. Results showed that the XI pathway could be functionally expressed in P. pastoris. After 50 generation of sequential batch cultivation, a set of domesticated recombinant P. pastoris strains with different performance metrics on xylose were obtained. One evolved strain showed the highest xylose assimilation ability, whose cell yield on xylose can even be comparable to that on glucose or glycerol. This strain also showed significantly increased β-mannanase production when cultured on xylose medium. Furthermore, transcription analysis of xylose pathway genes suggested that overexpression of XI and XK might be the key factors affecting effective xylose assimilation. To our best knowledge, this study is the first work demonstrating the construction of efficient xylose utilizing P. pastoris strains, thus providing a basis for using cellulosic biomass for bulk industrial enzyme production.

  3. Xylitol synthesis mutant of xylose-utilizing zymomonas for ethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Viitanen, Paul V.; Chou, Yat-Chen; McCutchen, Carol M.; Zhang, Min

    2010-06-22

    A strain of xylose-utilizing Zymomonas was engineered with a genetic modification to the glucose-fructose oxidoreductase gene resulting in reduced expression of GFOR enzyme activity. The engineered strain exhibits reduced production of xylitol, a detrimental by-product of xylose metabolism. It also consumes more xylose and produces more ethanol during mixed sugar fermentation under process-relevant conditions.

  4. 75 FR 8920 - Grant of Authority for Subzone Status; Danisco USA, Inc., Sweeteners Division (Xylitol, Xylose...

    Science.gov (United States)

    2010-02-26

    ... Status; Danisco USA, Inc., Sweeteners Division (Xylitol, Xylose, Galactose and Mannose); Thomson, IL... subzone at the xylitol, xylose, galactose and mannose manufacturing facility of Danisco USA, Inc... xylitol, xylose, galactose and mannose at the facility of Danisco USA, Inc., Sweeteners Division, located...

  5. Engineering of the redox imbalance of Fusarium oxysporum enables anaerobic growth on xylose

    DEFF Research Database (Denmark)

    Panagiotou, Gianni; Christakopoulos, Paul; Grotkjær, Thomas

    2006-01-01

    Dissimilatory nitrate reduction metabolism, of the natural xylose-fermenting fungus Fusarium oxysporum, was used as a strategy to achieve anaerobic growth and ethanol production from xylose. Beneficial alterations of the redox fluxes and thereby of the xylose metabolism were obtained by taking ad...

  6. Engineering industrial Saccharomyces cerevisiae strains for xylose fermentation and comparison for switchgrass conversion

    Science.gov (United States)

    Saccharomyces physiology and fermentation related properties vary broadly among industrial strains. In this study, six industrial strains of varied genetic background were engineered to ferment xylose. Aerobic growth rates on xylose were 0.040 h**-1 to 0.167 h**-1. Fermentation of xylose, glucose/xy...

  7. Rapid Discrimination between Candida glabrata, Candida nivariensis, and Candida bracarensis by Use of a Singleplex PCR ▿

    OpenAIRE

    Enache-Angoulvant, A.; Guitard, J.; Grenouillet, F.; Martin, T.; Durrens, P.; Fairhead, C.; Hennequin, C.

    2011-01-01

    We report here a PCR-based assay using a single primer pair targeting the RPL31 gene that allows discrimination between Candida glabrata, Candida bracarensis, and Candida nivariensis according to the size of the generated amplicon.

  8. Hichrom candida agar for identification of candida species

    OpenAIRE

    Baradkar V; Mathur M; Kumar S

    2010-01-01

    Chromogenic media are frequently used in direct and rapid identification of yeasts because different Candida species produce unique colors on these media. We used 60 isolates of Candida species including 30 C. albicans, 10 C. parapsilosis, 11 C. glabrata, five C. tropicalis, and four C. dubliniensis, isolated from various clinical specimens, to evaluate the performance of HiChrome Candida agar. These strains had been identified by germ tube test, morphology on cornmeal agar, chlamydospore for...

  9. Candida/Candida biofilms. First description of dual-species Candida albicans/C. rugosa biofilm.

    Science.gov (United States)

    Martins, Carlos Henrique Gomes; Pires, Regina Helena; Cunha, Aline Oliveira; Pereira, Cristiane Aparecida Martins; Singulani, Junya de Lacorte; Abrão, Fariza; Moraes, Thais de; Mendes-Giannini, Maria José Soares

    2016-04-01

    Denture liners have physical properties that favour plaque accumulation and colonization by Candida species, irritating oral tissues and causing denture stomatitis. To isolate and determine the incidence of oral Candida species in dental prostheses, oral swabs were collected from the dental prostheses of 66 patients. All the strains were screened for their ability to form biofilms; both monospecies and dual-species combinations were tested. Candida albicans (63 %) was the most frequently isolated microorganism; Candida tropicalis (14 %), Candida glabrata (13 %), Candida rugosa (5 %), Candida parapsilosis (3 %), and Candida krusei (2 %) were also detected. The XTT assay showed that C. albicans SC5314 possessed a biofilm-forming ability significantly higher (p biofilm was less than the total CFU of a monospecies C. albicans biofilm. In contrast to the profuse hyphae verified in monospecies C. albicans biofilms, micrographies showed that the C. albicans/non-albicans Candida biofilms consisted of sparse yeast forms and profuse budding yeast cells that generated a network. These results suggested that C. albicans and the tested Candida species could co-exist in biofilms displaying apparent antagonism. The study provide the first description of C. albicans/C. rugosa mixed biofilm. Copyright © 2016 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  10. Candida Infection of the Bloodstream - Candidemia

    Science.gov (United States)

    Candida Infection of the Bloodstream– Candidemia Fungal Disease Series #4 Candida is the single most important cause of fungal infections worldwide. In the U.S., Candida is the 4th most common cause of bloodstream ...

  11. The Candida Pathogenic Species Complex

    Science.gov (United States)

    Turner, Siobhán A.; Butler, Geraldine

    2014-01-01

    Candida species are the most common causes of fungal infection. Approximately 90% of infections are caused by five species: Candida albicans, Candida glabrata, Candida tropicalis, Candida parapsilosis, and Candida krusei. Three (C. albicans, C. tropicalis, and C. parapsilosis) belong to the CTG clade, in which the CTG codon is translated as serine and not leucine. C. albicans remains the most commonly isolated but is decreasing relative to the other species. The increasing incidence of C. glabrata is related to its reduced susceptibility to azole drugs. Genome analysis suggests that virulence in the CTG clade is associated with expansion of gene families, particularly of cell wall genes. Similar independent processes took place in the C. glabrata species group. Gene loss and expansion in an ancestor of C. glabrata may have resulted in preadaptations that enabled pathogenicity. PMID:25183855

  12. Metabolic control analysis of xylose catabolism in Aspergillus

    DEFF Research Database (Denmark)

    Prathumpai, Wai; Gabelgaard, J.B.; Wanchanthuek, P.

    2003-01-01

    , and flux control was shown to be dependent on the metabolite levels. Due to thermodynamic constraints, flux control may reside at the first step in the pathway, i.e., at the xylose reductase, even when the intracellular xylitol concentration is high. On the basis of the kinetic analysis, the general dogma...

  13. Xylose donor transport is critical for fungal virulence.

    Directory of Open Access Journals (Sweden)

    Lucy X Li

    2018-01-01

    Full Text Available Cryptococcus neoformans, an AIDS-defining opportunistic pathogen, is the leading cause of fungal meningitis worldwide and is responsible for hundreds of thousands of deaths annually. Cryptococcal glycans are required for fungal survival in the host and for pathogenesis. Most glycans are made in the secretory pathway, although the activated precursors for their synthesis, nucleotide sugars, are made primarily in the cytosol. Nucleotide sugar transporters are membrane proteins that solve this topological problem, by exchanging nucleotide sugars for the corresponding nucleoside phosphates. The major virulence factor of C. neoformans is an anti-phagocytic polysaccharide capsule that is displayed on the cell surface; capsule polysaccharides are also shed from the cell and impede the host immune response. Xylose, a neutral monosaccharide that is absent from model yeast, is a significant capsule component. Here we show that Uxt1 and Uxt2 are both transporters specific for the xylose donor, UDP-xylose, although they exhibit distinct subcellular localization, expression patterns, and kinetic parameters. Both proteins also transport the galactofuranose donor, UDP-galactofuranose. We further show that Uxt1 and Uxt2 are required for xylose incorporation into capsule and protein; they are also necessary for C. neoformans to cause disease in mice, although surprisingly not for fungal viability in the context of infection. These findings provide a starting point for deciphering the substrate specificity of an important class of transporters, elucidate a synthetic pathway that may be productively targeted for therapy, and contribute to our understanding of fundamental glycobiology.

  14. Recycling carbon dioxide during xylose fermentation by engineered Saccharomyces cerevisiae

    Science.gov (United States)

    In this study, we introduced the ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and phosphoribulokinase (PRK) into an engineered S. cerevisiae (SR8) harboring the XR/XDH pathway and up-regulated PPP 10, to enable CO2 recycling through a synthetic rPPP during xylose fermentation (Fig. 1). ...

  15. Evolutionary engineering of Saccharomyces cerevisiae for efficient aerobic xylose consumption

    DEFF Research Database (Denmark)

    Scalcinati, Gionata; Otero, José Manuel; Van Vleet, Jennifer R. H.

    2012-01-01

    Industrial biotechnology aims to develop robust microbial cell factories, such as Saccharomyces cerevisiae, to produce an array of added value chemicals presently dominated by petrochemical processes. Xylose is the second most abundant monosaccharide after glucose and the most prevalent pentose s...

  16. Evolutionary engineering of Saccharomyces cerevisiae for efficient aerobic xylose consumption

    Science.gov (United States)

    Gionata Scalcinati; Jose´ Manuel Otero; Jennifer R.H. Van Vleet; Thomas W. Jeffries; Lisbeth Olsson; Jens. Nielsen

    2012-01-01

    Industrial biotechnology aims to develop robust microbial cell factories, such as , to produce an array of added value chemicals presently dominated by petrochemical processes. Xylose is the second most abundant monosaccharide after glucose and the most prevalent pentose sugar found in lignocelluloses. Significant research...

  17. Xylose reductase from the thermophilic fungus Talaromyces emersonii

    Indian Academy of Sciences (India)

    Prakash

    Xylose reductase is involved in the first step of the fungal pentose catabolic pathway. The gene .... proteins with reversed coenzyme preference from NADPH to NADH ..... 399–404. Hasper A A, Visser J and de Graaff L H 2000 The Aspergillus.

  18. Impact of overexpressing NADH kinase on glucose and xylose metabolism in recombinant xylose-utilizing Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Hou, Jin; Vemuri, G. N.; Bao, X. M.

    2009-01-01

    of overexpressing the native NADH kinase (encoded by the POS5 gene) in xylose-consuming recombinant S. cerevisiae directed either into the cytosol or to the mitochondria was evaluated. The physiology of the NADH kinase containing strains was also evaluated during growth on glucose. Overexpressing NADH kinase...

  19. FarnesoI beyond morphogenesis controI: effect in Non- Candida albicans Candida species

    OpenAIRE

    Martins, Margarida Isabel Barros Coelho; Henriques, Mariana; Azeredo, Joana; Oliveira, Rosário

    2007-01-01

    Candididasis is one of the most important life-tbreatening opportunistic mycosis mainly occurring in individuais with impaired immunity. Although Candida albicans remains the most common fungai isolate, an increase in Non-Candida albicans Candida (NCAC) species is being reported. ln fact, Candida glabrata, Candida krusei, Candida parapsilosis and Candida tropicalis are emerging as clinically relevant pathogens. So it is of great importance to study the mechanisms of infection b...

  20. Purification and characterization of the d-xylose isomerase gene from Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Ho, N W.Y.; Rosenfeld, S; Stevis, P; Tsao, G T

    1983-11-01

    A DNA fragment containing both the Escherichia coli D-xylose isomerase (D-xylose ketol-isomerase, EC 5.3.1.5) gene and the D-xylulokinase (ATP: D-xylulose 5-phosphotransferase, EC 2.7.1.17) gene has been cloned on an E. coli plasmid. The D-xylose isomerase gene was separated from the D-xylulokinase gene by the construction of a new deletion plasmid, pLX7. The D-xylose isomerase gene cloned on pLX7 was found still to be an intact gene. The precise location of the D-xylose isomerase gene on the plasmid pLX7 was further determined by the construction of two more plasmids, pLX8 and pLX9. This is believed to be the first D-xylose isomerase gene that has been isolated and extensively purified from any organism. D-Xylose isomerase, the enzyme product of the D-xylose isomerase gene, is responsible for the conversion of D-xylose to D-xylulose, as well as D-glucose to D-fructose. It is widely believed that yeast cannot ferment D-xylose to ethanol primarily because of the lack of D-xylose isomerase in yeast. D-Xylose isomerase (also known as D-glucose isomerase) is also used for the commercial production of high-fructose syrups. The purification of the D-xylose isomerase gene may lead to the following industrial applications: (1) cloning and expression of the gene in yeast to make the latter organism capable of directly fermenting D-xylose to ethanol, and (2) cloning of the gene on a high-copy-number plasmid in a proper host to overproduce the enzyme, which should have a profound impact on the high-fructose syrup technology. 14 references.

  1. Hichrom candida agar for identification of Candida species.

    Science.gov (United States)

    Baradkar, V P; Mathur, M; Kumar, S

    2010-01-01

    Chromogenic media are frequently used in direct and rapid identification of yeasts because different Candida species produce unique colors on these media. We used 60 isolates of Candida species including 30 C. albicans, 10 C. parapsilosis, 11 C. glabrata, five C. tropicalis, and four C. dubliniensis, isolated from various clinical specimens, to evaluate the performance of HiChrome Candida agar. These strains had been identified by germ tube test, morphology on cornmeal agar, chlamydospore formation on tobacco agar and sugar assimilation tests. The sensitivity and specificity results were: C. albicans (96.55 and 96.42%); C. parapsilosis (80 and 98.03%), C. glabrata (90.90 and 88.23%), C. tropicalis (100 and 100%) and C. dubliniensis (60 and 96.55%) respectively. HiChrom Candida agaris medium has been useful and capable of presumptive, rapid identification of Candida species within 48 hours.

  2. Hichrom candida agar for identification of candida species

    Directory of Open Access Journals (Sweden)

    Baradkar V

    2010-01-01

    Full Text Available Chromogenic media are frequently used in direct and rapid identification of yeasts because different Candida species produce unique colors on these media. We used 60 isolates of Candida species including 30 C. albicans, 10 C. parapsilosis, 11 C. glabrata, five C. tropicalis, and four C. dubliniensis, isolated from various clinical specimens, to evaluate the performance of HiChrome Candida agar. These strains had been identified by germ tube test, morphology on cornmeal agar, chlamydospore formation on tobacco agar and sugar assimilation tests. The sensitivity and specificity results were: C. albicans (96.55 and 96.42%; C. parapsilosis (80 and 98.03%, C. glabrata (90.90 and 88.23%, C. tropicalis (100 and 100% and C. dubliniensis (60 and 96.55% respectively. HiChrom Candida agaris medium has been useful and capable of presumptive, rapid identification of Candida species within 48 hours.

  3. Intraspecific variation in a physiological thermoregulatory mechanism: the case of the lizard Liolaemus tenuis (Liolaeminae Variación intraespecífica en un mecanismo termorregulatorio fisiológico: el caso del lagarto Liolaemus tenuis (Liolaeminae

    Directory of Open Access Journals (Sweden)

    MARCELA A VIDAL

    2008-06-01

    Full Text Available The interspecific variation of heating rates in Liolaemus lizards, suggests an adaptive value of this physiological thermoregulatory mechanism, which would allow lizards to cope with the environmental thermal restrictions, imposed to behavioral thermoregulation. This trend has barely been tested at intraspecific level, and here we explore if intraspecific variation in heating rates occurs in Liolaemus tenuis, a relative widely distributed species from central Chile. We test the hypothesis that heating rates are related to the thermal environmental conditions at which populations are exposed, by comparing the heating rates of three populations (from a latitudinal range, which inhabit under different thermal conditions. Additionally, we explore if the intrinsic factor, sex, also modulates heating rates. There was a significant intraspecific variation in heating rates, at population and gender level. These rates however, showed only a partial relationship with the environmental thermal conditions. We found that the northern population, inhabiting at higher temperature, heated slower, which might reduce the risk of overheating. On the other hand, independent of the population, females heated slower than males. The meaning of this sexual variation is unclear, but may be consequence of the significant differences in genders' social behavior. Because males defend a territory with a harem, by heating faster, they can allocate extra time in behaviors associated to the defense and maintenance of the territory.La variación interespecífica en las tasas de calentamiento de Liolaemus pareciera ser un mecanismo fisiológico adaptativo que permitiría a los lagartos enfrentar restricciones térmicas ambientales impuestas a la termorregulación conductual. Esta tendencia ha sido raramente analizada a nivel intraespecífico y en este estudio exploramos si existe variación intraespecífica en las tasas de calentamiento de Liolaemus tenuis, una especie con rango

  4. [Discovery of the target genes inhibited by formic acid in Candida shehatae].

    Science.gov (United States)

    Cai, Peng; Xiong, Xujie; Xu, Yong; Yong, Qiang; Zhu, Junjun; Shiyuan, Yu

    2014-01-04

    At transcriptional level, the inhibitory effects of formic acid was investigated on Candida shehatae, a model yeast strain capable of fermenting xylose to ethanol. Thereby, the target genes were regulated by formic acid and the transcript profiles were discovered. On the basis of the transcriptome data of C. shehatae metabolizing glucose and xylose, the genes responsible for ethanol fermentation were chosen as candidates by the combined method of yeast metabolic pathway analysis and manual gene BLAST search. These candidates were then quantitatively detected by RQ-PCR technique to find the regulating genes under gradient doses of formic acid. By quantitative analysis of 42 candidate genes, we finally identified 10 and 5 genes as markedly down-regulated and up-regulated targets by formic acid, respectively. With regard to gene transcripts regulated by formic acid in C. shehatae, the markedly down-regulated genes ranking declines as follows: xylitol dehydrogenase (XYL2), acetyl-CoA synthetase (ACS), ribose-5-phosphate isomerase (RKI), transaldolase (TAL), phosphogluconate dehydrogenase (GND1), transketolase (TKL), glucose-6-phosphate dehydrogenase (ZWF1), xylose reductase (XYL1), pyruvate dehydrogenase (PDH) and pyruvate decarboxylase (PDC); and a declining rank for up-regulated gens as follows: fructose-bisphosphate aldolase (ALD), glucokinase (GLK), malate dehydrogenase (MDH), 6-phosphofructokinase (PFK) and alcohol dehydrogenase (ADH).

  5. Candida infections : detection and epidemiology

    NARCIS (Netherlands)

    Borst, A. (Annemarie)

    2002-01-01

    Despite the fact that the yeast Candida is the number 4 cause of bloodstream infections in the United States and ranks number 8 in Europe, adequate detection methods are lacking. Furthermore, relatively little is known about the epidemiology of Candida. Our aim was to improve the detection and

  6. An evolved xylose transporter from Zymomonas mobilis enhances sugar transport in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Zhang Jingqing

    2009-12-01

    Full Text Available Abstract Background Xylose is a second most abundant sugar component of lignocellulose besides glucose. Efficient fermentation of xylose is important for the economics of biomass-based biorefineries. However, sugar mixtures are sequentially consumed in xylose co-fermentation with glucose due to carbon catabolite repression (CCR in microorganisms. As xylose transmembrance transport is one of the steps repressed by CCR, it is therefore of interest to develop a transporter that is less sensitive to the glucose inhibition or CCR. Results The glucose facilitator protein Glf transporter from Zymomonas mobilis, also an efficient transporter for xylose, was chosen as the target transporter for engineering to eliminate glucose inhibition on xylose uptake. The evolution of Glf transporter was carried out with a mixture of glucose and xylose in E. coli. Error-prone PCR and random deletion were employed respectively in two rounds of evolution. Aided by a high-throughput screening assay using xylose analog p-nitrophenyl-β-D-xylopyranoside (pNPX in 96-well plates, a best mutant 2-RD5 was obtained that contains several mutations, and a deletion of 134 residues (about 28% of total residues, or three fewer transmembrane sections (TMSs. It showed a 10.8-fold improvement in terms of pNPX transport activity in the presence of glucose. The fermentation performance results showed that this mutant improved xylose consumption by 42% with M9 minimal medium containing 20 g L-1 xylose only, while with the mixture sugar of xylose and glucose, 28% more glucose was consumed, but no obvious co-utilization of xylose was observed. Further glucose fed-batch experiments suggested that the intracellular metabolism of xylose was repressed by glucose. Conclusions Through random mutagenesis and partial deletion coupled with high-throughput screening, a mutant of the Glf transporter (2-RD5 was obtained that relieved the inhibition of xylose transport by glucose. The fermentation

  7. The effect of CreA in glucose and xylose catabolism in Aspergillus nidulans

    DEFF Research Database (Denmark)

    Prathumpai, Wai; Mcintyre, Mhairi; Nielsen, Jens

    2004-01-01

    The catabolism of glucose and xylose was studied in a wild type and creA deleted (carbon catabolite de-repressed) strain of Aspergillus nidulans. Both strains were cultivated in bioreactors with either glucose or xylose as the sole carbon source, or in the presence of both sugars. In the cultivat......The catabolism of glucose and xylose was studied in a wild type and creA deleted (carbon catabolite de-repressed) strain of Aspergillus nidulans. Both strains were cultivated in bioreactors with either glucose or xylose as the sole carbon source, or in the presence of both sugars...... on the sugar mixture, glucose repression of xylose utilisation was observed; with xylose utilisation occurring only after glucose was depleted. This phenomenon was not seen in the creA deleted strain, where glucose and xylose were catabolised simultaneously. Measurement of key metabolites and the activities...... of key enzymes in the xylose utilisation pathway revealed that xylose metabolism was occurring in the creA deleted strain, even at high glucose concentrations. Conversely, in the wild type strain, activities of the key enzymes for xylose metabolism increased only when the effects of glucose repression...

  8. Saccharomyces cerevisiae engineered for xylose metabolism requires gluconeogenesis and the oxidative branch of the pentose phosphate pathway for aerobic xylose assimilation

    Science.gov (United States)

    Saccharomyces strains engineered to ferment xylose using Scheffersomyces stipitis xylose reductase (XR) and xylitol dehydrogenase (XDH) genes appear to be limited by metabolic imbalances due to differing cofactor specificities of XR and XDH. The S. stipitis XR, which uses nicotinamide adenine dinucl...

  9. Cumulative Effects of Nutrient Enrichment and Elevated Temperature Compromise the Early Life History Stages of the Coral Acropora tenuis.

    Science.gov (United States)

    Humanes, Adriana; Noonan, Sam H C; Willis, Bette L; Fabricius, Katharina E; Negri, Andrew P

    2016-01-01

    Inshore coral reefs are experiencing the combined pressures of excess nutrient availability associated with coastal activities and warming seawater temperatures. Both pressures are known to have detrimental effects on the early life history stages of hard corals, but studies of their combined effects on early demographic stages are lacking. We conducted a series of experiments to test the combined effects of nutrient enrichment (three levels) and elevated seawater temperature (up to five levels) on early life history stages of the inshore coral Acropora tenuis, a common species in the Indo-Pacific and Red Sea. Gamete fertilization, larval survivorship and larval settlement were all significantly reduced as temperature increased, but only fertilization was further affected by simultaneous nutrient enrichment. Combined high temperatures and nutrient enrichment affected fertilization in an additive manner, whereas embryo abnormalities increased synergistically. Higher than normal temperatures (32°C) increased coral juvenile growth rates 1.6-fold, but mortality also increased by 50%. The co-occurrence of nutrient enrichment with high temperatures reduced juvenile mortality to 36%, ameliorating temperature stress (antagonistic interaction). Overall, the types of effect (additive vs synergistic or antagonistic) and their magnitude varied among life stages. Gamete and embryo stages were more affected by temperature stress and, in some cases, also by nutrient enrichment than juveniles. The data suggest that coastal runoff events might exacerbate the impacts of warming temperatures on fertilization if these events co-occur during corals spawning. The cumulative impacts of simultaneous exposure to nutrient enrichment and elevated temperatures over all early life history stages increases the likelihood for failure of larval supply and recruitment for this coral species. Our results suggest that improving the water quality of river discharges into coastal areas might help to

  10. Cumulative Effects of Nutrient Enrichment and Elevated Temperature Compromise the Early Life History Stages of the Coral Acropora tenuis

    Science.gov (United States)

    Noonan, Sam H. C.; Willis, Bette L.; Fabricius, Katharina E.; Negri, Andrew P.

    2016-01-01

    Inshore coral reefs are experiencing the combined pressures of excess nutrient availability associated with coastal activities and warming seawater temperatures. Both pressures are known to have detrimental effects on the early life history stages of hard corals, but studies of their combined effects on early demographic stages are lacking. We conducted a series of experiments to test the combined effects of nutrient enrichment (three levels) and elevated seawater temperature (up to five levels) on early life history stages of the inshore coral Acropora tenuis, a common species in the Indo-Pacific and Red Sea. Gamete fertilization, larval survivorship and larval settlement were all significantly reduced as temperature increased, but only fertilization was further affected by simultaneous nutrient enrichment. Combined high temperatures and nutrient enrichment affected fertilization in an additive manner, whereas embryo abnormalities increased synergistically. Higher than normal temperatures (32°C) increased coral juvenile growth rates 1.6-fold, but mortality also increased by 50%. The co-occurrence of nutrient enrichment with high temperatures reduced juvenile mortality to 36%, ameliorating temperature stress (antagonistic interaction). Overall, the types of effect (additive vs synergistic or antagonistic) and their magnitude varied among life stages. Gamete and embryo stages were more affected by temperature stress and, in some cases, also by nutrient enrichment than juveniles. The data suggest that coastal runoff events might exacerbate the impacts of warming temperatures on fertilization if these events co-occur during corals spawning. The cumulative impacts of simultaneous exposure to nutrient enrichment and elevated temperatures over all early life history stages increases the likelihood for failure of larval supply and recruitment for this coral species. Our results suggest that improving the water quality of river discharges into coastal areas might help to

  11. 21 CFR 173.160 - Candida guilliermondii.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Candida guilliermondii. 173.160 Section 173.160... CONSUMPTION Enzyme Preparations and Microorganisms § 173.160 Candida guilliermondii. The food additive Candida... the following conditions: (a) The food additive is the enzyme system of the viable organism Candida...

  12. Xylose Fermentation by Saccharomyces cerevisiae: Challenges and Prospects

    Directory of Open Access Journals (Sweden)

    Danuza Nogueira Moysés

    2016-02-01

    Full Text Available Many years have passed since the first genetically modified Saccharomyces cerevisiae strains capable of fermenting xylose were obtained with the promise of an environmentally sustainable solution for the conversion of the abundant lignocellulosic biomass to ethanol. Several challenges emerged from these first experiences, most of them related to solving redox imbalances, discovering new pathways for xylose utilization, modulation of the expression of genes of the non-oxidative pentose phosphate pathway, and reduction of xylitol formation. Strategies on evolutionary engineering were used to improve fermentation kinetics, but the resulting strains were still far from industrial application. Lignocellulosic hydrolysates proved to have different inhibitors derived from lignin and sugar degradation, along with significant amounts of acetic acid, intrinsically related with biomass deconstruction. This, associated with pH, temperature, high ethanol, and other stress fluctuations presented on large scale fermentations led the search for yeasts with more robust backgrounds, like industrial strains, as engineering targets. Some promising yeasts were obtained both from studies of stress tolerance genes and adaptation on hydrolysates. Since fermentation times on mixed-substrate hydrolysates were still not cost-effective, the more selective search for new or engineered sugar transporters for xylose are still the focus of many recent studies. These challenges, as well as under-appreciated process strategies, will be discussed in this review.

  13. Combined enzyme mediated fermentation of cellulose and xylose to ethanol by Schizosaccharomyces pombe, cellulase, [beta]-glucosidase, and xylose isomerase

    Science.gov (United States)

    Lastick, S.M.; Mohagheghi, A.; Tucker, M.P.; Grohmann, K.

    1994-12-13

    A process for producing ethanol from mixed sugar streams from pretreated biomass comprising xylose and cellulose using enzymes to convert these substrates to fermentable sugars; selecting and isolating a yeast Schizosaccharomyces pombe ATCC No. 2476, having the ability to ferment these sugars as they are being formed to produce ethanol; loading the substrates with the fermentation mix composed of yeast, enzymes and substrates; fermenting the loaded substrates and enzymes under anaerobic conditions at a pH range of between about 5.0 to about 6.0 and at a temperature range of between about 35 C to about 40 C until the fermentation is completed, the xylose being isomerized to xylulose, the cellulose being converted to glucose, and these sugars being concurrently converted to ethanol by yeast through means of the anaerobic fermentation; and recovering the ethanol. 2 figures.

  14. Ethanol production from xylose by recombinant Saccharomyces cerevisiae expressing protein-engineered NADH-preferring xylose reductase from Pichia stipitis.

    Science.gov (United States)

    Watanabe, Seiya; Abu Saleh, Ahmed; Pack, Seung Pil; Annaluru, Narayana; Kodaki, Tsutomu; Makino, Keisuke

    2007-09-01

    A recombinant Saccharomyces cerevisiae strain transformed with xylose reductase (XR) and xylitol dehydrogenase (XDH) genes from Pichia stipitis (PsXR and PsXDH, respectively) has the ability to convert xylose to ethanol together with the unfavourable excretion of xylitol, which may be due to intercellular redox imbalance caused by the different coenzyme specificity between NADPH-preferring XR and NAD(+)-dependent XDH. In this study, we focused on the effect(s) of mutated NADH-preferring PsXR in fermentation. The R276H and K270R/N272D mutants were improved 52- and 146-fold, respectively, in the ratio of NADH/NADPH in catalytic efficiency [(k(cat)/K(m) with NADH)/(k(cat)/K(m) with NADPH)] compared with the wild-type (WT), which was due to decrease of k(cat) with NADPH in the R276H mutant and increase of K(m) with NADPH in the K270R/N272D mutant. Furthermore, R276H mutation led to significant thermostabilization in PsXR. The most positive effect on xylose fermentation to ethanol was found by using the Y-R276H strain, expressing PsXR R276H mutant and PsXDH WT: 20 % increase of ethanol production and 52 % decrease of xylitol excretion, compared with the Y-WT strain expressing PsXR WT and PsXDH WT. Measurement of intracellular coenzyme concentrations suggested that maintenance of the of NADPH/NADP(+) and NADH/NAD(+) ratios is important for efficient ethanol fermentation from xylose by recombinant S. cerevisiae.

  15. Selection of yeast Saccharomyces cerevisiae promoters available for xylose cultivation and fermentation.

    Science.gov (United States)

    Nambu-Nishida, Yumiko; Sakihama, Yuri; Ishii, Jun; Hasunuma, Tomohisa; Kondo, Akihiko

    2018-01-01

    To efficiently utilize xylose, a major sugar component of hemicelluloses, in Saccharomyces cerevisiae requires the proper expression of varied exogenous and endogenous genes. To expand the repertoire of promoters in engineered xylose-utilizing yeast strains, we selected promoters in S. cerevisiae during cultivation and fermentation using xylose as a carbon source. To select candidate promoters that function in the presence of xylose, we performed comprehensive gene expression analyses using xylose-utilizing yeast strains both during xylose and glucose fermentation. Based on microarray data, we chose 29 genes that showed strong, moderate, and weak expression in xylose rather than glucose fermentation. The activities of these promoters in a xylose-utilizing yeast strain were measured by lacZ reporter gene assays over time during aerobic cultivation and microaerobic fermentation, both in xylose and glucose media. In xylose media, P TDH3 , P FBA1 , and P TDH1 were favorable for high expression, and P SED1 , P HXT7 , P PDC1 , P TEF1 , P TPI1 , and P PGK1 were acceptable for medium-high expression in aerobic cultivation, and moderate expression in microaerobic fermentation. P TEF2 allowed moderate expression in aerobic culture and weak expression in microaerobic fermentation, although it showed medium-high expression in glucose media. P ZWF1 and P SOL4 allowed moderate expression in aerobic cultivation, while showing weak but clear expression in microaerobic fermentation. P ALD3 and P TKL2 showed moderate promoter activity in aerobic cultivation, but showed almost no activity in microaerobic fermentation. The knowledge of promoter activities in xylose cultivation obtained in this study will permit the control of gene expression in engineered xylose-utilizing yeast strains that are used for hemicellulose fermentation. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  16. NADPH-dependent D-aldose reductases and xylose fermentation in Fusarium oxysporum

    DEFF Research Database (Denmark)

    Panagiotou, Gianni; Christakopoulos, P.

    2004-01-01

    for NADPH over NADH. In this study, the influence of aeration and the response to the addition of electron acceptors on xylose fermentation by F. oxysporum were also studied. The batch cultivation of F. oxysporum on xylose was performed under aerobic, anaerobic and oxygen-limited conditions in stirred tank...... conditions (0.3 vvm). When the artificial electron acceptor acetoin was added to an anaerobic batch fermentation of xylose by F. oxysporum, the ethanol yield increased while xylitol excretion was also decreased....

  17. Biohydrogen production from xylose at extreme thermophilic temperatures (70 degrees C) by mixed culture fermentation

    DEFF Research Database (Denmark)

    Kongjan, Prawit; Min, Booki; Angelidaki, Irini

    2009-01-01

    /L. Addition of yeast extract in the cultivation medium resulted in significant improvement of hydrogen yield. The main metabolic products during xylose fermentation were acetate, ethanol, and lactate. The specific growth rates were able to fit the experimental points relatively well with Haldane equation...... solid wastes at 70 degrees C. The highest hydrogen yield of 1.62 +/- 0.02 mol-H-2/Mol-xylose(consumed) was obtained at initial xylose concentration of 0.5 g/L with synthetic medium amended with I g/L of yeast extract. Lower hydrogen yield was achieved at initial xylose concentration higher than 2 g...

  18. COMPOSICIÓN QUIMICA Y ACTIVIDAD ANTIFOULING DE LA FRACCION LIPIDICA DE LA ESPONJA MARINA Cliona tenuis (Clionidae

    Directory of Open Access Journals (Sweden)

    Leonardo Castellanos

    2009-04-01

    Full Text Available Normal 0 21 false false false st1\\:*{behavior:url(#ieooui } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} Del extracto orgánico de la esponja marina Cliona tenuis, recolectada en las Islas del Rosario (Colombia, Mar Caribe, fue obtenida la fracción lipídica, la cual presentó propiedades antifouling en pruebas en campo. Esta fracción fue separada por CC sobre gel de sílice hasta obtener fracciones de ésteres metílicos, glicéridos, glicolípidos, fosfolípidos y ácidos grasos libres, las cuales fueron identificadas por CCD y técnicas de dereplicación (RMN 1H y 13C. Posteriormente, las fracciones de glicéridos, glicolípidos y fosfolípidos fueron hidrolizadas y los ácidos obtenidos, junto con los provenientes de la fracción de ácidos grasos libres, fueron transformados en ésteres metílicos y todos se analizaron por CGAR-EM. Para ubicar las insaturaciones y ramificaciones, los ésteres metílicos se transformaron luego en sus correspondientes pirrolididas, las cuales también se analizaron por CGAR-EM. El estudio cromatográfico (valores de ECL y de los espectros de masas de los ésteres metílicos y de sus derivados pirrolididas permitió identificar 81 ácidos grasos diferentes, de los cuales no habían sido previamente reportados: los ácidos 4,8-hexadecadienoico, 11-metil-4,10-octadecadienoico, 6,9,12,14-icosatetraenoico, y 6,9,12,14,17-icosapentanoico.

  19. Candida Species Biofilms’ Antifungal Resistance

    Science.gov (United States)

    Silva, Sónia; Rodrigues, Célia F.; Araújo, Daniela; Rodrigues, Maria Elisa; Henriques, Mariana

    2017-01-01

    Candida infections (candidiasis) are the most prevalent opportunistic fungal infection on humans and, as such, a major public health problem. In recent decades, candidiasis has been associated to Candida species other than Candida albicans. Moreover, biofilms have been considered the most prevalent growth form of Candida cells and a strong causative agent of the intensification of antifungal resistance. As yet, no specific resistance factor has been identified as the sole responsible for the increased recalcitrance to antifungal agents exhibited by biofilms. Instead, biofilm antifungal resistance is a complex multifactorial phenomenon, which still remains to be fully elucidated and understood. The different mechanisms, which may be responsible for the intrinsic resistance of Candida species biofilms, include the high density of cells within the biofilm, the growth and nutrient limitation, the effects of the biofilm matrix, the presence of persister cells, the antifungal resistance gene expression and the increase of sterols on the membrane of biofilm cells. Thus, this review intends to provide information on the recent advances about Candida species biofilm antifungal resistance and its implication on intensification of the candidiasis. PMID:29371527

  20. A formal synthesis of (+-muricatacin from D-xylose

    Directory of Open Access Journals (Sweden)

    VELIMIR POPSAVIN

    2003-11-01

    Full Text Available A multistep route towards the aldehydo-lactone 19, the final chiral precursor in a new stereospecific synthesis of (+-muricatacin, has been developed starting from D-xylose. The key step of the synthesis involves an E-selective Wittig olefination of the lactol 6 with methoxycarbonylmethylidene triphenylphosphorane, followed by successive catalytic reduction and g-lactonisation processes. Subsequent selective functional groups interconversions furnished the key six-carbon intermediate 19, which can be converted into the (+-muricatacin via a three-step sequence already described in the chemical literature.

  1. High prevalence of oral colonization by Candida dubliniensis in HIV-positive patients in Argentina.

    Science.gov (United States)

    Binolfi, Andrés; Biasoli, Marisa S; Luque, Alicia G; Tosello, María E; Magaró, Hortensia M

    2005-08-01

    Candida dubliniensis is a recently described yeast species, closely related to Candida albicans. This work represents the first general survey of the carriage of C. dubliniensis in the oral cavities of HIV-positive patients in Argentina. We studied 133 strains isolated from 162 HIV-positive patients, using the following identification tests: chlamydospore production on corn meal agar with Tween 80; colony color on CHROMagar Candida media; differential growth at 45 degrees C on potato dextrose agar; D-xylose assimilation; chlamydospore formation on sunflower seed agar (SSA); carbohydrate assimilation profiles using the API 20 C Aux commercial kit and PCR using primers that hybridize to the class IV intron of the ACT1 gene. Out of the 133 strains, 21 were identified as C. dubliniensis, representing approximately 13% of the 162 patients in this study. From these data, we conclude that although the PCR assay is the most reliable method, clamydospore formation on SSA is an easier and less expensive test for the screening of C. dubliniensis in the routine laboratory. Our results show that C. dubliniensis has a high prevalence among HIV-positive patients in Argentina.

  2. Xylose Isomerization with Zeolites in a Two-Step Alcohol–Water Process

    DEFF Research Database (Denmark)

    Paniagua, Marta; Shunmugavel, Saravanamurugan; Melián Rodriguez, Mayra

    2015-01-01

    Isomerization of xylose to xylulose was efficiently catalyzed by large-pore zeolites in a two-step methanol–water process that enhanced the product yield significantly. The reaction pathway involves xylose isomerization to xylulose, which, in part, subsequently reacts with methanol to form methyl...

  3. Alcoholic glucose and xylose fermentations by the coculture process: Compatability and typing of associated strains

    Energy Technology Data Exchange (ETDEWEB)

    Laplace, J.M.; Delgenes, J.P.; Moletta, R. (Institut national de la recherche agronomique, Narbonne (France)); Navarro, J.M. (Universite de Montpellier (France))

    1992-01-01

    As part of the simulaneous fermentation of both glucose and xylose to ethanol by a coculture process, compatibilities between xylose-fermenting yeasts and glucose-fermenting species were investigated. Among the Saccharomyces species tested, none inhibited growth of the xylose-fermenting yeasts. By contrast, many xylose-fermenting yeasts, among the 11 tested, exerted an inhibitory effect on growth of the selected Saccharomyces species. Killer character was demonstrated in three strains of Pichia stipitis. Such strains, despite their high fermentative performances, cannot be used to ferment D-xylose in association with the selected Saccharomyces species. From compatibility tests between xylose-fermenting yeasts and Saccharomyces species, pairs of microorganisms suitable for simultaneous xylose and glucose fermentations by coculture are proposed. Strains associated in the coculture process are distinguished by their resistance to mitochondrial inhibitors. The xylose-fermenting yeasts are able to grow on media containing erythromycin (1 g/l) or diuron (50 mg/l), whereas, the Saccharomyces species are inhibited by these mitochondrial inhibitors. 15 refs., 2 figs., 3 tabs.

  4. A synthetic hybrid promoter for xylose-regulated control of gene expression in Saccharomyces yeasts

    Science.gov (United States)

    Metabolism of non-glucose carbon sources is often highly regulated at the transcriptional and post-translational levels. This level of regulation is lacking in Saccharomyces cerevisiae strains engineered to metabolize xylose. To better control transcription in S. cerevisiae, the xylose-dependent, DN...

  5. Use of agricultural by-products for the production of xylitol. I. The production of xylose

    Energy Technology Data Exchange (ETDEWEB)

    De Menezes, H C

    1976-01-01

    A Rhizopus species capable of converting xylan into xylose was isolated from the soil, and purified. The xylanase produced by this fungus was capable of producing xylose from corn cob, wheat bran, and rice hulls without prior extraction of the xylan.

  6. Ethanol production using xylitol synthesis mutant of xylose-utilizing zymomonas

    Science.gov (United States)

    Viitanen, Paul V.; McCutchen, Carol M.; Emptage, Mark; Caimi, Perry G.; Zhang, Min; Chou, Yat-Chen

    2010-06-22

    Production of ethanol using a strain of xylose-utilizing Zymomonas with a genetic modification of the glucose-fructose oxidoreductase gene was found to be improved due to greatly reduced production of xylitol, a detrimental by-product of xylose metabolism synthesized during fermentation.

  7. Increased xylose affinity of Hxt2 through gene shuffling of hexose transporters in Saccharomyces cerevisiae

    NARCIS (Netherlands)

    Nijland, Jeroen G; Shin, Hyun Yong; de Waal, Paul P; Klaassen, Paul; Driessen, Arnold J M

    AIMS: Optimizing D-xylose transport in Saccharomyces cerevisiae is essential for efficient bioethanol production from cellulosic materials. We have used a gene shuffling approach of hexose (Hxt) transporters in order to increase the affinity for D-xylose. METHODS AND RESULTS: Various libraries were

  8. Continuous xylose fermentation by Clostridium acetobutylicum – Kinetics and energetics issues under acidogenesis conditions

    NARCIS (Netherlands)

    Procentese, A.; Raganati, F.; Olivieri, G.; Russo, M.E.; Salatino, P.; Marzocchella, A.

    2014-01-01

    The paper reports the assessment of the growth kinetics of Clostridium acetobutylicum DSM 792 adopting xylose as carbon source. Xylose is the fundamental component of hemicellulose hydrolysis, a relevant fraction of lignocellulosic feedstocks for biofuel production. Tests were carried out in a CSTR

  9. Establishment of oxidative D-xylose metabolism in Pseudomonas putida S12

    NARCIS (Netherlands)

    Meijnen, J.P.; Winde, J.H. de; Ruijssenaars, H.J.

    2009-01-01

    The oxidative D-xylose catabolic pathway of Caulobacter crescentus, encoded by the xylXABCD operon, was expressed in the gram-negative bacterium Pseudomonas putida S12. This engineered transformant strain was able to grow on D-xylose as a sole carbon source with a biomass yield of 53% (based on g

  10. Ethanol production from xylose in engineered Saccharomyces cerevisiae strains. Current state and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Matsushika, Akinori; Inoue, Hiroyuki; Sawayama, Shigeki [National Inst. of Advanced Industrial Science and Technology (AIST), Hiroshima (JP). Biomass Technology Research Center (BTRC); Kodaki, Tsutomu [Kyoto Univ. (Japan). Inst. of Advanced Energy

    2009-08-15

    Bioethanol production from xylose is important for utilization of lignocellulosic biomass as raw materials. The research on yeast conversion of xylose to ethanol has been intensively studied especially for genetically engineered Saccharomyces cerevisiae during the last 20 years. S. cerevisiae, which is a very safe microorganism that plays a traditional and major role in industrial bioethanol production, has several advantages due to its high ethanol productivity, as well as its high ethanol and inhibitor tolerance. However, this yeast cannot ferment xylose, which is the dominant pentose sugar in hydrolysates of lignocellulosic biomass. A number of different strategies have been applied to engineer yeasts capable of efficiently producing ethanol from xylose, including the introduction of initial xylose metabolism and xylose transport, changing the intracellular redox balance, and overexpression of xylulokinase and pentose phosphate pathways. In this review, recent progress with regard to these studies is discussed, focusing particularly on xylose-fermenting strains of S. cerevisiae. Recent studies using several promising approaches such as host strain selection and adaptation to obtain further improved xylose-utilizing S. cerevisiae are also addressed. (orig.)

  11. Bilateral polymicrobial osteomyelitis with Candida tropicalis and Candida krusei: a case report and an updated literature review

    DEFF Research Database (Denmark)

    Kaldau, Niels Christian; Brorson, Stig; Jensen, Poul Einar

    2012-01-01

    We present a case of bilateral polymicrobial osteomyelitis with Candida tropicalis and Candida krusei, and review the literature on Candida osteomyelitis.......We present a case of bilateral polymicrobial osteomyelitis with Candida tropicalis and Candida krusei, and review the literature on Candida osteomyelitis....

  12. Rational and evolutionary engineering approaches uncover a small set of genetic changes efficient for rapid xylose fermentation in Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Soo Rin Kim

    Full Text Available Economic bioconversion of plant cell wall hydrolysates into fuels and chemicals has been hampered mainly due to the inability of microorganisms to efficiently co-ferment pentose and hexose sugars, especially glucose and xylose, which are the most abundant sugars in cellulosic hydrolysates. Saccharomyces cerevisiae cannot metabolize xylose due to a lack of xylose-metabolizing enzymes. We developed a rapid and efficient xylose-fermenting S. cerevisiae through rational and inverse metabolic engineering strategies, comprising the optimization of a heterologous xylose-assimilating pathway and evolutionary engineering. Strong and balanced expression levels of the XYL1, XYL2, and XYL3 genes constituting the xylose-assimilating pathway increased ethanol yields and the xylose consumption rates from a mixture of glucose and xylose with little xylitol accumulation. The engineered strain, however, still exhibited a long lag time when metabolizing xylose above 10 g/l as a sole carbon source, defined here as xylose toxicity. Through serial-subcultures on xylose, we isolated evolved strains which exhibited a shorter lag time and improved xylose-fermenting capabilities than the parental strain. Genome sequencing of the evolved strains revealed that mutations in PHO13 causing loss of the Pho13p function are associated with the improved phenotypes of the evolved strains. Crude extracts of a PHO13-overexpressing strain showed a higher phosphatase activity on xylulose-5-phosphate (X-5-P, suggesting that the dephosphorylation of X-5-P by Pho13p might generate a futile cycle with xylulokinase overexpression. While xylose consumption rates by the evolved strains improved substantially as compared to the parental strain, xylose metabolism was interrupted by accumulated acetate. Deletion of ALD6 coding for acetaldehyde dehydrogenase not only prevented acetate accumulation, but also enabled complete and efficient fermentation of xylose as well as a mixture of glucose and

  13. Engineering of xylose reductase and overexpression of xylitol dehydrogenase and xylulokinase improves xylose alcoholic fermentation in the thermotolerant yeast Hansenula polymorpha

    Directory of Open Access Journals (Sweden)

    Voronovsky Andriy Y

    2008-07-01

    Full Text Available Abstract Background The thermotolerant methylotrophic yeast Hansenula polymorpha is capable of alcoholic fermentation of xylose at elevated temperatures (45 – 48°C. Such property of this yeast defines it as a good candidate for the development of an efficient process for simultaneous saccharification and fermentation. However, to be economically viable, the main characteristics of xylose fermentation of H. polymorpha have to be improved. Results Site-specific mutagenesis of H. polymorpha XYL1 gene encoding xylose reductase was carried out to decrease affinity of this enzyme toward NADPH. The modified version of XYL1 gene under control of the strong constitutive HpGAP promoter was overexpressed on a Δxyl1 background. This resulted in significant increase in the KM for NADPH in the mutated xylose reductase (K341 → R N343 → D, while KM for NADH remained nearly unchanged. The recombinant H. polymorpha strain overexpressing the mutated enzyme together with native xylitol dehydrogenase and xylulokinase on Δxyl1 background was constructed. Xylose consumption, ethanol and xylitol production by the constructed strain were determined for high-temperature xylose fermentation at 48°C. A significant increase in ethanol productivity (up to 7.3 times was shown in this recombinant strain as compared with the wild type strain. Moreover, the xylitol production by the recombinant strain was reduced considerably to 0.9 mg × (L × h-1 as compared to 4.2 mg × (L × h-1 for the wild type strain. Conclusion Recombinant strains of H. polymorpha engineered for improved xylose utilization are described in the present work. These strains show a significant increase in ethanol productivity with simultaneous reduction in the production of xylitol during high-temperature xylose fermentation.

  14. D-Xylose from waste liquors of a viscose process

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, T; Mimura, M

    1977-12-14

    D-Xylose was prepared in good yields by neutralizing alkali waste liquors containing hemicellulose (I) with inorganic acids, dialyzing to remove salts hydrolyzing with acids, fermenting to decompose hexose, decolorizing, concentrating to < 15% sugars, treating with alcohols to precipitate oligosugars, removing the precipitate, and crystalizing. Thus, 1 kg waste liquor containing 27 g I was neutralized with 5% HCl, dialyzed at 15/sup 0/ for 48 h with parchment paper, concentrated at 40/sup 0/ to give a 500 g solution containing 7% H/sub 2/SO/sub 4/, boiled for 3 h, neutralized with BaCO/sub 3/, mixed with 10 g yeast at pH 5.4 to 5.8 (filtrate) fermented at 35/sup 0/ for 12 h, filtered, decolorized, concentrated at 40/sup 0/ to > 80 g mixed with EtOH to give a precipitate, filtered, concentrated to 17 g syrup, and mixed with AcOH to obtain 7.2 g D-Xylose.

  15. A Novel Technique that Enables Efficient Conduct of Simultaneous Isomerization and Fermentation (SIF) of Xylose

    Science.gov (United States)

    Rao, Kripa; Chelikani, Silpa; Relue, Patricia; Varanasi, Sasidhar

    Of the sugars recovered from lignocellulose, D-glucose can be readily converted into ethanol by baker's or brewer's yeast (Saccharomyces cerevisiae). However, xylose that is obtained by the hydrolysis of the hemicellulosic portion is not fermentable by the same species of yeasts. Xylose fermentation by native yeasts can be achieved via isomerization of xylose to its ketose isomer, xylulose. Isomerization with exogenous xylose isomerase (XI) occurs optimally at a pH of 7-8, whereas subsequent fermentation of xylulose to ethanol occurs at a pH of 4-5. We present a novel scheme for efficient isomerization of xylose to xylulose at conditions suitable for the fermentation by using an immobilized enzyme system capable of sustaining two different pH microenvironments in a single vessel. The proof-of-concept of the two-enzyme pellet is presented, showing conversion of xylose to xylulose even when the immobilized enzyme pellets are suspended in a bulk solution whose pH is sub-optimal for XI activity. The co-immobilized enzyme pellets may prove extremely valuable in effectively conducting "simultaneous isomerization and fermentation" (SIF) of xylose. To help further shift the equilibrium in favor of xylulose formation, sodium tetraborate (borax) was added to the isomerization solution. Binding of tetrahydroxyborate ions to xylulose effectively reduces the concentration of xylulose and leads to increased xylose isomerization. The formation of tetrahydroxyborate ions and the enhancement in xylulose production resulting from the complexation was studied at two different bulk pH values. The addition of 0.05 M borax to the isomerization solution containing our co-immobilized enzyme pellets resulted in xylose to xylulose conversion as high as 86% under pH conditions that are suboptimal for XI activity. These initial findings, which can be optimized for industrial conditions, have significant potential for increasing the yield of ethanol from xylose in an SIF approach.

  16. Effect of Candida albicans and Candida dubliniensis planktonic/biofilm quorum sensing molecules on yeast morphogenesis

    OpenAIRE

    Henriques, Mariana; Martins, Margarida Isabel Barros Coelho; Azeredo, Joana; Oliveira, Rosário

    2006-01-01

    One of the aims of this work was to study the effect of farnesol, a quorum sensing molecule for Candida albicans, on morphologic inhibition of Candida dubliniensis. The second goal of this work was to confirm if Candida dubliniensis also excreted quorum sensing molecules, on both planktonic and biofilm forms. The results clearly demonstrate that Candida dubliniensis undergoes morphological alterations triggered by farnesol. It was also found that supernatants of Candida dubliniensis and Ca...

  17. Impact of xylose and mannose on central metabolism of yeast Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Pitkaenen, J.P.

    2005-07-01

    In this study, understanding of the central metabolism was improved by quantification of metabolite concentrations, enzyme activities, protein abundances, and gene transcript concentrations. Intracellular fluxes were estimated by applying stoichiometric models of metabolism. The methods were applied in the study of yeast Saccharomyces cerevisiae in two separate projects. A xylose project aimed at improved utilization of D- xylose as a substrate for, e.g., producing biomaterial- based fuel ethanol. A mannose project studied the production of GDP-mannose from D-mannose in a strain lacking the gene for phosphomannose isomerase (PMI40 deletion). Hexose, D-glucose is the only sugar more abundant than pentose D-xylose. D-xylose is common in hardwoods (e.g. birch) and crop residues (ca. 25% of dry weight). However, S. cerevisiae is unable to utilize D- xylose without a recombinant pathway where D-xylose is converted to Dxylulose. In this study D-xylose was converted in two steps via xylitol: by D-xylose reductase and xylitol dehydrogenase encoded by XYL1 and XYL2 from Pichia stipitis, respectively. Additionally, endogenous xylulokinase (XKS1) was overexpressed in order to increase the consumption of D-xylose by enhancing the phosphorylation of D-xylulose. Despite of the functional recombinant pathway the utilization rates of D xylose still remained low. This study proposes a set of limitations that are responsible for the low utilization rates of D-xylose under microaerobic conditions. Cells compensated for the cofactor imbalance, caused by the conversion of D-xylose to D- xylulose, by increasing the flux through the oxidative pentose phosphate pathway and by shuttling NADH redox potential to mitochondrion to be oxidized in oxidative phosphorylation. However, mitochondrial NADH inhibits citrate synthase in citric acid cycle, and consequently lower flux through citric acid cycle limits oxidative phosphorylation. Further, limitations in the uptake of D- xylose, in the

  18. Variation in the health and biochemical condition of the coral Acropora tenuis along two water quality gradients on the Great Barrier Reef, Australia.

    Science.gov (United States)

    Rocker, Melissa M; Francis, David S; Fabricius, Katharina E; Willis, Bette L; Bay, Line K

    2017-06-30

    This study explores how plasticity in biochemical attributes, used as indicators of health and condition, enables the coral Acropora tenuis to respond to differing water quality regimes in inshore regions of the Great Barrier Reef. Health attributes were monitored along a strong and weak water quality gradient, each with three reefs at increasing distances from a major river source. Attributes differed significantly only along the strong gradient; corals grew fastest, had the least dense skeletons, highest symbiont densities and highest lipid concentrations closest to the river mouth, where water quality was poorest. High nutrient and particulate loads were only detrimental to skeletal density, which decreased as linear extension increased, highlighting a trade-off. Our study underscores the importance of assessing multiple health attributes in coral reef monitoring. For example, autotrophic indices are poor indicators of coral health and condition, but improve when combined with attributes like lipid content and biomass. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Differentiation of Candida albicans, Candida glabrata, and Candida krusei by FT-IR and chemometrics by CHROMagar™ Candida.

    Science.gov (United States)

    Wohlmeister, Denise; Vianna, Débora Renz Barreto; Helfer, Virginia Etges; Calil, Luciane Noal; Buffon, Andréia; Fuentefria, Alexandre Meneghello; Corbellini, Valeriano Antonio; Pilger, Diogo André

    2017-10-01

    Pathogenic Candida species are detected in clinical infections. CHROMagar™ is a phenotypical method used to identify Candida species, although it has limitations, which indicates the need for more sensitive and specific techniques. Infrared Spectroscopy (FT-IR) is an analytical vibrational technique used to identify patterns of metabolic fingerprint of biological matrixes, particularly whole microbial cell systems as Candida sp. in association of classificatory chemometrics algorithms. On the other hand, Soft Independent Modeling by Class Analogy (SIMCA) is one of the typical algorithms still little employed in microbiological classification. This study demonstrates the applicability of the FT-IR-technique by specular reflectance associated with SIMCA to discriminate Candida species isolated from vaginal discharges and grown on CHROMagar™. The differences in spectra of C. albicans, C. glabrata and C. krusei were suitable for use in the discrimination of these species, which was observed by PCA. Then, a SIMCA model was constructed with standard samples of three species and using the spectral region of 1792-1561cm -1 . All samples (n=48) were properly classified based on the chromogenic method using CHROMagar™ Candida. In total, 93.4% (n=45) of the samples were correctly and unambiguously classified (Class I). Two samples of C. albicans were classified correctly, though these could have been C. glabrata (Class II). Also, one C. glabrata sample could have been classified as C. krusei (Class II). Concerning these three samples, one triplicate of each was included in Class II and two in Class I. Therefore, FT-IR associated with SIMCA can be used to identify samples of C. albicans, C. glabrata, and C. krusei grown in CHROMagar™ Candida aiming to improve clinical applications of this technique. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Candida Infections and Human Defensins.

    Science.gov (United States)

    Polesello, Vania; Segat, Ludovica; Crovella, Sergio; Zupin, Luisa

    2017-01-01

    Candida species infections are an important worldwide health issue since they do not only affect immunocompromised patients but also healthy individuals. The host developed different mechanisms of protection against Candida infections; specifically the immune system and the innate immune response are the first line of defence. Defensis are a group of antimicrobial peptides, components of the innate immunity, produced at mucosal level and known to be active against bacteria, virus but also fungi. The aim of the current work was to review all previous studies in literature that analysed defensins in the context of Candida spp. infections, in order to investigate and clarify the exact mechanisms of defensins anti-fungal action. Several studies were identified from 1985 to 2017 (9 works form years 1985 to 1999, 44 works ranging from 2000 to 2009 and 35 from 2010 to 2017) searched in two electronic databases (PubMed and Google Scholar). The main key words used for the research were "Candida", "Defensins"," Innate immune system","fungi". The findings of the reviewed studies highlight the pivotal role of defensins antimicrobial peptides in the immune response against Candida infections, since they are able to discriminate host cell from fungi: defensins are able to recognize the pathogens cell wall (different in composition from the human ones), and to disrupt it through membrane permeabilization. However, further research is needed to explain completely defensins' mechanisms of action to fight C. albicans (and other Candida spp.) infections, being the information fragmentary and only in part elucidated. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  1. Onycholysis caused by Candida Krusei

    Directory of Open Access Journals (Sweden)

    Rao S

    2004-01-01

    Full Text Available Onycholysis caused by Candida krusei is rare. A 21 years old male patient presented with grayish discolouration and elevation of all fingernails since one year. Patient was refractory to treatment with fluconazole. Potassium hydroxide preparation of subungual debris revealed fungal elements. Growth on Sabouraud dextrose agar was identified by cultural characteristics, morphotyping, microscopy and biochemical tests as Candida krusei. The isolate was resistant to fluconazole and amphotericin-B but susceptible to nystatin and clotrimazole. Patient responded well to clotrimazole and terbinafine.

  2. Production of furfural from rice straw by microbial treatment. (II). Production of furfural from xylose by acid treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, W.S.; Yoo, I.S.; Kang, S.K.

    1984-01-01

    The reaction conditions and mechanism of furfural production from xylose by acid treatment were studied. The xylose was obtained from rice straw. Furfural yield at batch-isothermal conditions was a function of initial xylose concentration H2SO4 concentration, reaction temperature and reaction time. And when the initial xylose concentration was low, the results were consistent with those of Root's reaction mechanism. Maximum furfural yield was obtained under conditions of H2SO4 concentration 0.2N, initial xylose concentration 0.0067 M, temperature 200 degrees, and reaction time 10 min.

  3. Furfural tolerance and detoxification mechanism in Candida tropicalis.

    Science.gov (United States)

    Wang, Shizeng; Cheng, Gang; Joshua, Chijioke; He, Zijun; Sun, Xinxiao; Li, Ruimin; Liu, Lexuan; Yuan, Qipeng

    2016-01-01

    Current biomass pretreatment by hydrothermal treatment (including acid hydrolysis, steam explosion, and high-temperature steaming) and ionic liquids generally generate inhibitors to the following fermentation process. Furfural is one of the typical inhibitors generated in hydrothermal treatment of biomass. Furfural could inhibit cell growth rate and decrease biofuel productivity of microbes. Candida tropicalis is a promising microbe for the production of biofuels and value-added chemicals using hemicellulose hydrolysate as carbon source. In this study, C. tropicalis showed a comparable ability of furfural tolerance during fermentation. We investigated the mechanism of C. tropicalis 's robust tolerance to furfural and relevant metabolic responses to obtain more information for metabolic engineering of microbes for efficient lignocellulose fermentation. Candida tropicalis showed comparable intrinsic tolerance to furfural and a fast rate of furfural detoxification. C. tropicalis 's half maximal inhibitory concentration for furfural with xylose as the sole carbon source was 3.69 g/L, which was higher than that of most wild-type microbes reported in the literature to our knowledge. Even though furfural prolonged the lag phase of C. tropicalis , the final biomass in the groups treated with 1 g/L furfural was slightly greater than that in the control groups. By real-time PCR analysis, we found that the expression of ADH1 in C. tropicalis ( ctADH1 ) was induced by furfural and repressed by ethanol after furfural depletion. The expression of ctADH1 could be regulated by both furfural and ethanol. After the disruption of gene ctADH1 , we found that C. tropicalis 's furfural tolerance was weakened. To further confirm the function of ctADH1 and enhance Escherichia coli 's furfural tolerance, ctADH1 was overexpressed in E. coli BL21 (DE3). The rate of furfural degradation in E. coli BL21 (DE3) with pET-ADH1 (high-copy plasmid) and pCS-ADH1 (medium-copy plasmid) was increased

  4. Engineering genome-reduced Bacillus subtilis for acetoin production from xylose.

    Science.gov (United States)

    Yan, Panpan; Wu, Yuanqing; Yang, Li; Wang, Zhiwen; Chen, Tao

    2018-02-01

    To investigate the capacity of a genome-reduced Bacillus subtilis strain as chassis cell for acetoin production from xylose. To endow the genome-reduced Bacillus subtilis strain BSK814 with the ability to utilize xylose, we inserted a native xyl operon into its genome and deleted the araR gene. The resulting strain BSK814A2 produced 2.94 g acetoin/l from 10 g xylose/l, which was 39% higher than control strain BSK19A2. The deletion of the bdhA and acoA genes further improved xylose utilization efficiency and increased acetoin production to 3.71 g/l in BSK814A4. Finally, BSK814A4 produced up to 23.3 g acetoin/l from 50 g xylose/l, with a yield of 0.46 g/g xylose. Both the titer and yield were 39% higher than those of control strain BSK19A4. As a chassis cell, genome-reduced B. subtilis showed significantly improved capacity for the production of the overflow product acetoin from xylose compared with wild-type strain.

  5. Densities, molar volumes, and isobaric expansivities of (d-xylose+hydrochloric acid+water) systems

    International Nuclear Information System (INIS)

    Zhang Qiufen; Yan Zhenning; Wang Jianji; Zhang Hucheng

    2006-01-01

    Densities of (d-xylose+HCl+water) have been measured at temperature in the range (278.15 to 318.15) K as a function of concentration of both d-xylose and hydrochloric acid. The densities have been used to estimate the molar volumes and isobaric expansivity of the ternary solutions. The molar volumes of the ternary solutions vary linearly with mole fraction of d-xylose. The standard partial molar volumes V 2,φ - bar for d-xylose in aqueous solutions of molality (0.2, 0.4, 0.7, 1.1, 1.6, and 2.1) mol.kg -1 HCl have been determined. In the investigated temperature range, the relation: V 2,φ - bar =c 1 +c 2 {(T/K)-273.15} 1/2 , can be used to describe the temperature dependence of the standard partial molar volumes. These results have, in conjunction with the results obtained in water, been used to deduce the standard volumes of transfer, Δ t V - bar , of d-xylose from water to aqueous HCl solutions. An increase in the transfer volume of d-xylose with increasing HCl concentrations has been explained by the stronger interactions of H + with the hydrophilic groups of d-xylose

  6. Engineering of the redox imbalance of Fusarium oxysporum enables anaerobic growth on xylose.

    Science.gov (United States)

    Panagiotou, Gianni; Christakopoulos, Paul; Grotkjaer, Thomas; Olsson, Lisbeth

    2006-09-01

    Dissimilatory nitrate reduction metabolism, of the natural xylose-fermenting fungus Fusarium oxysporum, was used as a strategy to achieve anaerobic growth and ethanol production from xylose. Beneficial alterations of the redox fluxes and thereby of the xylose metabolism were obtained by taking advantage of the regeneration of the cofactor NAD(+) during the denitrification process. In batch cultivations, nitrate sustained growth under anaerobic conditions (1.21 g L(-1) biomass) and simultaneously a maximum yield of 0.55 moles of ethanol per mole of xylose was achieved, whereas substitution of nitrate with ammonium limited the growth significantly (0.15 g L(-1) biomass). Using nitrate, the maximum acetate yield was 0.21 moles per mole of xylose and no xylitol excretion was observed. Furthermore, the network structure in the central carbon metabolism of F. oxysporum was characterized in steady state. F. oxysporum grew anaerobically on [1-(13)C] labelled glucose and unlabelled xylose in chemostat cultivation with nitrate as nitrogen source. The use of labelled substrate allowed the precise determination of the glucose and xylose contribution to the carbon fluxes in the central metabolism of this poorly described microorganism. It was demonstrated that dissimilatory nitrate reduction allows F. oxysporum to exhibit typical respiratory metabolic behaviour with a highly active TCA cycle and a large demand for NADPH.

  7. Synthetic arylquinuclidine derivatives exhibit antifungal activity against Candida albicans, Candida tropicalis and Candida parapsilopsis

    Directory of Open Access Journals (Sweden)

    Gilbert Ian

    2011-01-01

    Full Text Available Abstract Background Sterol biosynthesis is an essential pathway for fungal survival, and is the biochemical target of many antifungal agents. The antifungal drugs most widely used to treated fungal infections are compounds that inhibit cytochrome P450-dependent C14α-demethylase (CYP51, but other enzymes of this pathway, such as squalene synthase (SQS which catalyses the first committed step in sterol biosynthesis, could be viable targets. The aim of this study was to evaluate the antifungal activity of SQS inhibitors on Candida albicans, Candida tropicalis and Candida parapsilopsis strains. Methods Ten arylquinuclidines that act as SQS inhibitors were tested as antiproliferative agents against three ATCC strains and 54 clinical isolates of Candida albicans, Candida tropicalis and Candida parapsilopsis. Also, the morphological alterations induced in the yeasts by the experimental compounds were evaluated by fluorescence and transmission electron microscopy. Results The most potent arylquinuclidine derivative (3-[1'-{4'-(benzyloxy-phenyl}]-quinuclidine-2-ene (WSP1267 had a MIC50 of 2 μg/ml for all species tested and MIC90 varying from 4 μg/ml to 8 μg/ml. Ultrathin sections of C. albicans treated with 1 μg/ml of WSP1267 showed several ultrastructural alterations, including (a loss of cell wall integrity, (b detachment of the plasma membrane from the fungal cell wall, (c accumulation of small vesicles in the periplasmic region, (d presence of large electron-dense vacuoles and (e significantly increased cell size and cell wall thickness. In addition, fluorescence microscopy of cells labelled with Nile Red showed an accumulation of lipid droplets in the cytoplasm of treated yeasts. Nuclear staining with DAPI revealed the appearance of uncommon yeast buds without a nucleus or with two nuclei. Conclusion Taken together, our data demonstrate that arylquinuclidine derivatives could be useful as lead compounds for the rational synthesis of new

  8. An efficient xylose-fermenting recombinant Saccharomyces cerevisiae strain obtained through adaptive evolution and its global transcription profile

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yu; Chen, Xiao; Peng, Bingyin; Chen, Liyuan; Hou, Jin; Bao, Xiaoming [Shandong Univ., Jinan (China). State Key Lab. of Microbial Technology

    2012-11-15

    Factors related to ethanol production from xylose in engineered Saccharomyces cerevisiae that contain an exogenous initial metabolic pathway are still to be elucidated. In the present study, a strain that expresses the xylose isomerase gene of Piromyces sp. Pi-xylA and overexpresses XKS1, RPE1, RKI1, TAL1, and TKL1, with deleted GRE3 and COX4 genes was constructed. The xylose utilization capacity of the respiratory deficiency strain was poor but improved via adaptive evolution in xylose. The {mu}{sub max} of the evolved strain in 20 gl{sup -1} xylose is 0.11 {+-} 0.00 h{sup -1}, and the evolved strain consumed 17.83 gl{sup -1} xylose within 72 h, with an ethanol yield of 0.43 gg{sup -1} total consumed sugars during glucose-xylose cofermentation. Global transcriptional changes and effect of several specific genes were studied. The result revealed that the increased xylose isomerase activity, the upregulation of enzymes involved in glycolysis and glutamate synthesis, and the downregulation of trehalose and glycogen synthesis, may have contributed to the improved xylose utilization of the strain. Furthermore, the deletion of PHO13 decreased the xylose growth in the respiration deficiency strain although deleting PHO13 can improve the xylose metabolism in other strains. (orig.)

  9. Molecular screening for Candida orthopsilosis and Candida metapsilosis among Danish Candida parapsilosis group blood culture isolates: proposal of a new RFLP profile for differentiation

    DEFF Research Database (Denmark)

    Mirhendi, Hossein; Bruun, Brita; Schønheyder, Henrik Carl

    2010-01-01

    Candida orthopsilosis and Candida metapsilosis are recently described species phenotypically indistinguishable from Candida parapsilosis . We evaluated phenotyping and molecular methods for the detection of these species among 79 unique blood culture isolates of the C. parapsilosis group obtained...

  10. Transport of D-xylose in Lactobacillus pentosus, Lactobacillus casei, and Lactobacillus plantarum: Evidence for a mechanism of facilitated diffusion via the phosphoenolpyruvate:mannose phosphotransferase system

    NARCIS (Netherlands)

    Chaillou, S.; Pouwels, P.H.; Postma, P.W.

    1999-01-01

    We have identified and characterized the D-xylose transport system of Lactobacillus pentosus. Uptake of D-xylose was not driven by the proton motive force generated by malolactic fermentation and required D-xylose metabolism. The kinetics of D-xylose transport were indicative of a low- affinity

  11. Microwave-Assisted Green Production of Furfural from D-xylose of Sugarcane Bagasse

    Directory of Open Access Journals (Sweden)

    Sílvio Vaz Jr.

    2015-10-01

    Full Text Available D-xylose is a component of sugarcane bagasse that can be used as a renewable resource for the production of a variety of chemicals. By means of catalytic reactions in an aqueous medium, it was determined that D-xylose can efficiently be converted into furfural by the application of microwave as a green synthetic methodology. The highest yields of furfural were obtained at a HCl concentration of 4 mg/mL. When the reaction was performed at 200 °C, an optimum yield of 64% of furfural was observed after 10 min of reaction time, with 95% of the D-xylose being converted.

  12. Special Issue: Candida and Candidiasis

    Directory of Open Access Journals (Sweden)

    Jeniel E. Nett

    2018-06-01

    Full Text Available This special issue highlights emerging topics related to Candida, the most prevalent fungal pathogen in the hospital setting. The advantages and limitations of new, non-culture based diagnostic techniques are discussed. The issue reviews mammalian and non-mammalian infection models. The manuscripts present updates on several molecular mechanisms of pathogenicity, including filamentation, biofilm formation, and phospholipid production.

  13. Candida biofilms: is adhesion sexy?

    Science.gov (United States)

    Soll, David R

    2008-08-26

    The development of Candida albicans biofilms requires two types of adhesion molecule - the Als proteins and Hwp1. Mutational analyses have recently revealed that these molecules play complementary roles, and their characteristics suggest that they may have evolved from primitive mating agglutinins.

  14. Xylose isomerase improves growth and ethanol production rates from biomass sugars for both Saccharomyces pastorianus and Saccharomyces cerevisiae.

    Science.gov (United States)

    Miller, Kristen P; Gowtham, Yogender Kumar; Henson, J Michael; Harcum, Sarah W

    2012-01-01

    The demand for biofuel ethanol made from clean, renewable nonfood sources is growing. Cellulosic biomass, such as switch grass (Panicum virgatum L.), is an alternative feedstock for ethanol production; however, cellulosic feedstock hydrolysates contain high levels of xylose, which needs to be converted to ethanol to meet economic feasibility. In this study, the effects of xylose isomerase on cell growth and ethanol production from biomass sugars representative of switch grass were investigated using low cell density cultures. The lager yeast species Saccharomyces pastorianus was grown with immobilized xylose isomerase in the fermentation step to determine the impact of the glucose and xylose concentrations on the ethanol production rates. Ethanol production rates were improved due to xylose isomerase; however, the positive effect was not due solely to the conversion of xylose to xylulose. Xylose isomerase also has glucose isomerase activity, so to better understand the impact of the xylose isomerase on S. pastorianus, growth and ethanol production were examined in cultures provided fructose as the sole carbon. It was observed that growth and ethanol production rates were higher for the fructose cultures with xylose isomerase even in the absence of xylose. To determine whether the positive effects of xylose isomerase extended to other yeast species, a side-by-side comparison of S. pastorianus and Saccharomyces cerevisiae was conducted. These comparisons demonstrated that the xylose isomerase increased ethanol productivity for both the yeast species by increasing the glucose consumption rate. These results suggest that xylose isomerase can contribute to improved ethanol productivity, even without significant xylose conversion. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  15. Evaluation of nutrient supplementation to charcoal-treated and untreated rice straw hydrolysate for xylitol production by Candida guilliermondii

    Directory of Open Access Journals (Sweden)

    Solange Inês Mussatto

    2005-05-01

    Full Text Available Xylitol was produced by Candida guilliermondii from charcoal-treated and untreated rice straw hemicellulosic hydrolysate with or without nutrients (ammonium sulphate, calcium chloride, rice bran extract. Both, xylitol yield and volumetric productivity decreased significantly when the nutrients were added to treated and untreated hydrolysates. In the treated hydrolysate, the efficiency of xylose conversion to xylitol was 79% when the nutrients were omitted. The results demonstrated that rice straw hemicellulosic hydrolysate treated with activated charcoal was a cheap source of xylose and other nutrients for xylitol production by C. guilliermondii. The non-necessity of adding nutrients to the hydrolysate media would be very advantageous since the process becomes less costly.Este trabalho avaliou a produção de xilitol pela levedura Candida guilliermondii, a partir de hidrolisado hemicelulósico de palha de arroz não tratado e tratado com carvão ativo, ambos suplementados ou não com nutrientes (sulfato de amônio, cloreto de cálcio e extrato de farelo de arroz. Os resultados mostraram que tanto o rendimento como a produtividade volumétrica em xilitol diminuíram quando os nutrientes foram adicionados em ambos hidrolisados, tratado e não tratado. Em hidrolisado tratado, a eficiência de conversão de xilose em xilitol foi de 79% quando em ausência de nutrientes. Estes resultados mostram que o hidrolisado hemicelulósico de palha de arroz tratado com carvão ativo é uma fonte barata de xilose e outros nutrientes, para a produção de xilitol por Candida guilliermondii. A não necessidade de adicionar nutrientes ao meio a base de hidrolisado é muito vantajosa, uma vez que o processo se torna mais econômico.

  16. Genes related to xylose fermentation and methods of using same for enhanced biofuel production

    Science.gov (United States)

    Wohlbach, Dana J.; Gasch, Audrey P.

    2014-08-05

    The present invention provides isolated gene sequences involved in xylose fermentation and related recombinant yeast which are useful in methods of enhanced biofuel production, particularly ethanol production. Methods of bioengineering recombinant yeast useful for biofuel production are also provided.

  17. Genomic sequence of the xylose fermenting, insect-inhabitingyeast, Pichia stipitis

    Energy Technology Data Exchange (ETDEWEB)

    Jeffries, Thomas W.; Grigoriev, Igor; Grimwood, Jane; Laplaza,Jose M.; Aerts, Andrea; Salamov, Asaf; Schmutz, Jeremy; Lindquist, Erika; Dehal, Paramvir; Shapiro, Harris; Jin, Yong-Su; Passoth, Volkmar; Richardson, Paul M.

    2007-06-25

    Xylose is a major constituent of angiosperm lignocellulose,so its fermentation is important for bioconversion to fuels andchemicals. Pichia stipitis is the best-studied native xylose fermentingyeast. Genes from P. stipitis have been used to engineer xylosemetabolism in Saccharomycescerevisiae, and the regulation of the P.stipitis genome offers insights into the mechanisms of xylose metabolismin yeasts. We have sequenced, assembled and finished the genome ofP.stipitis. As such, it is one of only a handful of completely finishedeukaryotic organisms undergoing analysis and manual curation. Thesequence has revealed aspects of genome organization, numerous genes forbiocoversion, preliminary insights into regulation of central metabolicpathways, numerous examples of co-localized genes with related functions,and evidence of how P. stipitis manages to achieve redox balance whilegrowing on xylose under microaerobic conditions.

  18. Improved xylose and arabinose utilization by an industrial recombinant Saccharomyces cerevisiae strain using evolutionary engineering

    DEFF Research Database (Denmark)

    Sanchez, R.G.; Karhumaa, Kaisa; Fonseca, C.

    2010-01-01

    Background: Cost-effective fermentation of lignocellulosic hydrolysate to ethanol by Saccharomyces cerevisiae requires efficient mixed sugar utilization. Notably, the rate and yield of xylose and arabinose co-fermentation to ethanol must be enhanced. Results: Evolutionary engineering was used...... to improve the simultaneous conversion of xylose and arabinose to ethanol in a recombinant industrial Saccharomyces cerevisiae strain carrying the heterologous genes for xylose and arabinose utilization pathways integrated in the genome. The evolved strain TMB3130 displayed an increased consumption rate...... of our knowledge, this is the first report that characterizes the molecular mechanisms for improved mixed-pentose utilization obtained by evolutionary engineering of a recombinant S. cerevisiae strain. Increased transport of pentoses and increased activities of xylose converting enzymes contributed...

  19. Reaction mechanisms and kinetics of processing glucose, xylose and glucose-xylose mixtures under hot compressed water conditions for predicting bio-crude composition

    DEFF Research Database (Denmark)

    Grigoras, Ionela; Toor, Saqib Sohail; Rosendahl, Lasse Aistrup

    Mechanisms for bio-crude formation during the conversion of glucose, xylose and glucose-xylose mixtures as biomass model compounds under hot compressed water conditions are investigated. Studies in literature have shown that the diverse products formed at the early stages of glucose or xylose...... conversion are 5-HMF, erythrose, glyceraldehyde, dihydroxyacetone, pyruvaldehyde, and saccharinic acids resulted through reactions such as dehydration, retro-aldol condensation and isomerization. However, these compounds are mostly water soluble compounds and lack the final steps towards formation of water...... insoluble components at longer reaction times. The effects of pressure, pH, catalyst and reaction time on the main products are examined thoroughly. The possible routes for the formation of oil compounds are developed....

  20. The effect of initial cell concentration on xylose fermentation by Pichia stipitis

    Science.gov (United States)

    Frank K. Agbogbo; Guillermo Coward-Kelly; Mads Torry-Smith; Kevin Wenger; Thomas W. Jeffries

    2007-01-01

    Xylose was fermented using Pichia stipitis CBS 6054 at different initial cell concentrations. A high initial cell concentration increased the rate of xylose utilization, ethanol formation, and the ethanol yield. The highest ethanol concentration of 41.0 g/L and a yield of 0.38 g/g was obtained using an initial cell concentration of 6.5 g/L. Even though more xylitol was...

  1. Separation of xylose oligomers using centrifugal partition chromatography with a butanol-methanol-water system.

    Science.gov (United States)

    Lau, Ching-Shuan; Clausen, Edgar C; Lay, Jackson O; Gidden, Jennifer; Carrier, Danielle Julie

    2013-01-01

    Xylose oligomers are the intermediate products of xylan depolymerization into xylose monomers. An understanding of xylan depolymerization kinetics is important to improve the conversion of xylan into monomeric xylose and to minimize the formation of inhibitory products, thereby reducing ethanol production costs. The study of xylan depolymerization requires copious amount of xylose oligomers, which are expensive if acquired commercially. Our approach consisted of producing in-house oligomer material. To this end, birchwood xylan was used as the starting material and hydrolyzed in hot water at 200 °C for 60 min with a 4 % solids loading. The mixture of xylose oligomers was subsequently fractionated by a centrifugal partition chromatography (CPC) with a solvent system of butanol:methanol:water in a 5:1:4 volumetric ratio. Operating in an ascending mode, the butanol-rich upper phase (the mobile phase) eluted xylose oligomers from the water-rich stationary phase at a 4.89 mL/min flow rate for a total fractionation time of 300 min. The elution of xylose oligomers occurred between 110 and 280 min. The yields and purities of xylobiose (DP 2), xylotriose (DP 3), xylotetraose (DP 4), and xylopentaose (DP 5) were 21, 10, 14, and 15 mg/g xylan and 95, 90, 89, and 68 %, respectively. The purities of xylose oligomers from this solvent system were higher than those reported previously using tetrahydrofuran:dimethyl sulfoxide:water in a 6:1:3 volumetric ratio. Moreover, the butanol-based solvent system improved overall procedures by facilitating the evaporation of the solvents from the CPC fractions, rendering the purification process more efficient.

  2. Mutants of Pachysolen tannophilus with Improved Production of Ethanol from d-Xylose

    OpenAIRE

    Lee, Hung; James, Allen P.; Zahab, Diana M.; Mahmourides, George; Maleszka, Ryszard; Schneider, Henry

    1986-01-01

    The conversion of d-xylose to ethanol by the yeast Pachysolen tannophilus is relatively inefficient in batch culture. The inefficiency has been attributed in part to concurrent utilization of ethanol in the presence of appreciable concentrations of d-xylose and to the formation of xylitol and other by-products. To increase the concentration of ethanol accumulated in batch cultures, UV-induced mutants of P. tannophilus were selected on the basis of diminished growth on ethanol. Eleven independ...

  3. Bulk segregant analysis by high-throughput sequencing reveals a novel xylose utilization gene from Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Jared W Wenger

    2010-05-01

    Full Text Available Fermentation of xylose is a fundamental requirement for the efficient production of ethanol from lignocellulosic biomass sources. Although they aggressively ferment hexoses, it has long been thought that native Saccharomyces cerevisiae strains cannot grow fermentatively or non-fermentatively on xylose. Population surveys have uncovered a few naturally occurring strains that are weakly xylose-positive, and some S. cerevisiae have been genetically engineered to ferment xylose, but no strain, either natural or engineered, has yet been reported to ferment xylose as efficiently as glucose. Here, we used a medium-throughput screen to identify Saccharomyces strains that can increase in optical density when xylose is presented as the sole carbon source. We identified 38 strains that have this xylose utilization phenotype, including strains of S. cerevisiae, other sensu stricto members, and hybrids between them. All the S. cerevisiae xylose-utilizing strains we identified are wine yeasts, and for those that could produce meiotic progeny, the xylose phenotype segregates as a single gene trait. We mapped this gene by Bulk Segregant Analysis (BSA using tiling microarrays and high-throughput sequencing. The gene is a putative xylitol dehydrogenase, which we name XDH1, and is located in the subtelomeric region of the right end of chromosome XV in a region not present in the S288c reference genome. We further characterized the xylose phenotype by performing gene expression microarrays and by genetically dissecting the endogenous Saccharomyces xylose pathway. We have demonstrated that natural S. cerevisiae yeasts are capable of utilizing xylose as the sole carbon source, characterized the genetic basis for this trait as well as the endogenous xylose utilization pathway, and demonstrated the feasibility of BSA using high-throughput sequencing.

  4. Pulsed addition of HMF and furfural to batch-grown xylose-utilizing Saccharomyces cerevisiae results in different physiological responses in glucose and xylose consumption phase

    Science.gov (United States)

    2013-01-01

    Background Pretreatment of lignocellulosic biomass generates a number of undesired degradation products that can inhibit microbial metabolism. Two of these compounds, the furan aldehydes 5-hydroxymethylfurfural (HMF) and 2-furaldehyde (furfural), have been shown to be an impediment for viable ethanol production. In the present study, HMF and furfural were pulse-added during either the glucose or the xylose consumption phase in order to dissect the effects of these inhibitors on energy state, redox metabolism, and gene expression of xylose-consuming Saccharomyces cerevisiae. Results Pulsed addition of 3.9 g L-1 HMF and 1.2 g L-1 furfural during either the glucose or the xylose consumption phase resulted in distinct physiological responses. Addition of furan aldehydes in the glucose consumption phase was followed by a decrease in the specific growth rate and the glycerol yield, whereas the acetate yield increased 7.3-fold, suggesting that NAD(P)H for furan aldehyde conversion was generated by acetate synthesis. No change in the intracellular levels of NAD(P)H was observed 1 hour after pulsing, whereas the intracellular concentration of ATP increased by 58%. An investigation of the response at transcriptional level revealed changes known to be correlated with perturbations in the specific growth rate, such as protein and nucleotide biosynthesis. Addition of furan aldehydes during the xylose consumption phase brought about an increase in the glycerol and acetate yields, whereas the xylitol yield was severely reduced. The intracellular concentrations of NADH and NADPH decreased by 58 and 85%, respectively, hence suggesting that HMF and furfural drained the cells of reducing power. The intracellular concentration of ATP was reduced by 42% 1 hour after pulsing of inhibitors, suggesting that energy-requiring repair or maintenance processes were activated. Transcriptome profiling showed that NADPH-requiring processes such as amino acid biosynthesis and sulfate and

  5. Statistical optimization of fermentative hydrogen production from xylose by newly isolated Enterobacter sp. CN1

    Energy Technology Data Exchange (ETDEWEB)

    Long, Chuannan; Cui, Jingjing; Liu, Zuotao; Liu, Yuntao; Hu, Zhong [Department of Biology, Shantou University, Shantou 515063 (China); Long, Minnan [The School of Energy Research, Xiamen University, Xiamen 361005 (China)

    2010-07-15

    Statistical experimental designs were applied for the optimization of medium constituents for hydrogen production from xylose by newly isolated Enterobacter sp. CN1. Using Plackett-Burman design, xylose, FeSO{sub 4} and peptone were identified as significant variables which highly influenced hydrogen production. The path of steepest ascent was undertaken to approach the optimal region of the three significant factors. These variables were subsequently optimized using Box-Behnken design of response surface methodology (RSM). The optimum conditions were found to be xylose 16.15 g/L, FeSO{sub 4} 250.17 mg/L, peptone 2.54 g/L. Hydrogen production at these optimum conditions was 1149.9 {+-} 65 ml H{sub 2}/L medium. Under different carbon sources condition, the cumulative hydrogen volume were 1217 ml H{sub 2}/L xylose medium, 1102 ml H{sub 2}/L glucose medium and 977 ml H{sub 2}/L sucrose medium; the maximum hydrogen yield were 2.0 {+-} 0.05 mol H{sub 2}/mol xylose, 0.64 mol H{sub 2}/mol glucose. Fermentative hydrogen production from xylose by Enterobacter sp. CN1 was superior to glucose and sucrose. (author)

  6. Design of Xylose-Based Semisynthetic Polyurethane Tissue Adhesives with Enhanced Bioactivity Properties.

    Science.gov (United States)

    Balcioglu, Sevgi; Parlakpinar, Hakan; Vardi, Nigar; Denkbas, Emir Baki; Karaaslan, Merve Goksin; Gulgen, Selam; Taslidere, Elif; Koytepe, Suleyman; Ates, Burhan

    2016-02-01

    Developing biocompatible tissue adhesives with high adhesion properties is a highly desired goal of the tissue engineering due to adverse effects of the sutures. Therefore, our work involves synthesis, characterization, adhesion properties, protein adsorption, in vitro biodegradation, in vitro and in vivo biocompatibility properties of xylose-based semisynthetic polyurethane (NPU-PEG-X) bioadhesives. Xylose-based semisynthetic polyurethanes were developed by the reaction among 4,4'-methylenebis(cyclohexyl isocyanate) (MCI), xylose and polyethylene glycol 200 (PEG). Synthesized polyurethanes (PUs) showed good thermal stability and high adhesion strength. The highest values in adhesion strength were measured as 415.0 ± 48.8 and 94.0 ± 2.8 kPa for aluminum substrate and muscle tissue in 15% xylose containing PUs (NPU-PEG-X-15%), respectively. The biodegradation of NPU-PEG-X-15% was also determined as 19.96 ± 1.04% after 8 weeks of incubation. Relative cell viability of xylose containing PU was above 86%. Moreover, 10% xylose containing NPU-PEG-X (NPU-PEG-X-10%) sample has favorable tissue response, and inflammatory reaction between 1 and 6 weeks implantation period. With high adhesiveness and biocompatibility properties, NPU-PEG-X can be used in the medical field as supporting materials for preventing the fluid leakage after abdominal surgery or wound closure.

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

    Science.gov (United States)

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

    2016-06-01

    The efficient co-fermentation of glucose and xylose is necessary for the economically feasible bioethanol production from lignocellulosic biomass. Even with xylose utilizing Saccharomyces cerevisiae, the efficiency of the lignocellulosic ethanol production remains suboptimal mainly due to the low conversion yield of xylose to ethanol. In this study, we evaluated the co-fermentation performances of SXA-R2P-E, a recently engineered isomerase-based xylose utilizing strain, in mixed sugars and in lignocellulosic hydrolysates. In a high-sugar fermentation with 70g/L of glucose and 40g/L of xylose, SXA-R2P-E produced 50g/L of ethanol with an yield of 0.43gethanol/gsugars at 72h. From dilute acid-pretreated hydrolysates of rice straw and hardwood (oak), the strain produced 18-21g/L of ethanol with among the highest yield of 0.43-0.46gethanol/gsugars ever reported. This study shows a highly promising potential of a xylose isomerase-expressing strain as an industrially relevant ethanol producer from lignocellulosic hydrolysates. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Enhanced production of extracellular inulinase by the yeast Kluyveromyces marxianus in xylose catabolic state.

    Science.gov (United States)

    Hoshida, Hisashi; Kidera, Kenta; Takishita, Ryuta; Fujioka, Nobuhisa; Fukagawa, Taiki; Akada, Rinji

    2018-06-01

    The production of extracellular proteins by the thermotolerant yeast Kluyveromyces marxianus, which utilizes various sugars, was investigated using media containing sugars such as glucose, galactose, and xylose. SDS-PAGE analysis of culture supernatants revealed abundant production of an extracellular protein when cells were grown in xylose medium. The N-terminal sequence of the extracellular protein was identical to a part of the inulinase encoded by INU1 in the genome. Inulinase is an enzyme hydrolyzing β-2,1-fructosyl bond in inulin and sucrose and is not required for xylose assimilation. Disruption of INU1 in the strain DMKU 3-1042 lost the production of the extracellular protein and resulted in growth defect in sucrose and inulin media, indicating that the extracellular protein was inulinase (sucrase). In addition, six K. marxianus strains among the 16 strains that were analyzed produced more inulinase in xylose medium than in glucose medium. However, expression analysis indicated that the INU1 promoter activity was lower in the xylose medium than in the glucose medium, suggesting that enhanced production of inulinase is controlled in a post-transcriptional manner. The production of inulinase was also higher in cultures with more agitation, suggesting that oxygen supply affects the production of inulinase. Taken together, these results suggest that both xylose and oxygen supply shift cellular metabolism to enhance the production of extracellular inulinase. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    Ishola, Mofoluwake M.; Ylitervo, Päivi; Taherzadeh, Mohammad J.

    2015-01-01

    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. PMID:26633530

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

    Directory of Open Access Journals (Sweden)

    Mofoluwake M. Ishola

    2015-12-01

    Full Text Available 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.

  11. Utilization of xylose as a carbon source for mixotrophic growth of Scenedesmus obliquus.

    Science.gov (United States)

    Yang, Suling; Liu, Guijun; Meng, Youting; Wang, Ping; Zhou, Sijing; Shang, Hongzhong

    2014-11-01

    Mixotrophic cultivation is one potential mode for microalgae production, and an economically acceptable and environmentally sustainable organic carbon source is essential. The potential use of xylose for culturing Scenedesmus obliquus in a mixotrophic mode and physiological features of xylose-grown S. obliquus were studied. S. obliquus had a certain xylose tolerance, and was capable of utilizing xylose for growth. At a xylose concentration of 4gL(-1), the maximal cell density was 2.2gL(-1), being 2.9-fold of that under photoautotrophic condition and arriving to the level of mixotrophic growth using 4gL(-1) glucose. No changes in cellular morphology of the cells grown with or without xylose were detected. Fluorescence emission from photosystem II (PS II) relative to photosystem I (PS I) was decreased in mixotrophic cells, implying that the PSII activity was decreased. The biomass lipid content was enhanced and carbohydrate concentration was decreased, in relation to photoautotrophic controls. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Evolutionary Adaptation of Kluyveromyces marxianus NIRE-K3 for Enhanced Xylose Utilization

    International Nuclear Information System (INIS)

    Sharma, Nilesh Kumar; Behera, Shuvashish; Arora, Richa; Kumar, Sachin

    2017-01-01

    The evolutionary adaptation was approached on the thermotolerant yeast Kluyveromyces marxianus NIRE-K3 at 45°C on xylose as a sole source of carbon for enhancement of xylose uptake. After 60 cycles, evolved strain K. marxianus NIRE-K3.1 showed comparatively 3.75- and 3.0-fold higher specific growth and xylose uptake rates, respectively, than that of native strain. Moreover, the short lag phase was also observed on adapted strain. During batch fermentation with xylose concentration of 30 g l −1 , K. marxianus NIRE-K3.1 could utilize about 96% of xylose in 72 h and produced 4.67 and 15.7 g l −1 of ethanol and xylitol, respectively, which were 9.72- and 4.63-fold higher than that of native strain. Similarly, specific sugar consumption rate, xylitol, and ethanol yields were 5.07-, 1.15-, and 2.44-fold higher as compared to the native strain, respectively. The results obtained after evolutionary adaptation of K. marxianus NIRE-K3 show the significant improvement in the xylose utilization, ethanol and xylitol yields, and productivities. By understanding the results obtained, the significance of evolutionary adaptation has been rationalized, since the adapted culture could be more stable and could enhance the productivity.

  13. Lactic acid production from xylose by engineered Saccharomyces cerevisiae without PDC or ADH deletion.

    Science.gov (United States)

    Turner, Timothy L; Zhang, Guo-Chang; Kim, Soo Rin; Subramaniam, Vijay; Steffen, David; Skory, Christopher D; Jang, Ji Yeon; Yu, Byung Jo; Jin, Yong-Su

    2015-10-01

    Production of lactic acid from renewable sugars has received growing attention as lactic acid can be used for making renewable and bio-based plastics. However, most prior studies have focused on production of lactic acid from glucose despite that cellulosic hydrolysates contain xylose as well as glucose. Microbial strains capable of fermenting both glucose and xylose into lactic acid are needed for sustainable and economic lactic acid production. In this study, we introduced a lactic acid-producing pathway into an engineered Saccharomyces cerevisiae capable of fermenting xylose. Specifically, ldhA from the fungi Rhizopus oryzae was overexpressed under the control of the PGK1 promoter through integration of the expression cassette in the chromosome. The resulting strain exhibited a high lactate dehydrogenase activity and produced lactic acid from glucose or xylose. Interestingly, we observed that the engineered strain exhibited substrate-dependent product formation. When the engineered yeast was cultured on glucose, the major fermentation product was ethanol while lactic acid was a minor product. In contrast, the engineered yeast produced lactic acid almost exclusively when cultured on xylose under oxygen-limited conditions. The yields of ethanol and lactic acid from glucose were 0.31 g ethanol/g glucose and 0.22 g lactic acid/g glucose, respectively. On xylose, the yields of ethanol and lactic acid were substrates.

  14. Evolutionary Adaptation of Kluyveromyces marxianus NIRE-K3 for Enhanced Xylose Utilization

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Nilesh Kumar [Biochemical Conversion Division, Sardar Swaran Singh National Institute of Bio-Energy, Kapurthala (India); I. K. Gujral Punjab Technical University, Kapurthala (India); Behera, Shuvashish; Arora, Richa; Kumar, Sachin, E-mail: sachin.biotech@gmail.com [Biochemical Conversion Division, Sardar Swaran Singh National Institute of Bio-Energy, Kapurthala (India)

    2017-12-12

    The evolutionary adaptation was approached on the thermotolerant yeast Kluyveromyces marxianus NIRE-K3 at 45°C on xylose as a sole source of carbon for enhancement of xylose uptake. After 60 cycles, evolved strain K. marxianus NIRE-K3.1 showed comparatively 3.75- and 3.0-fold higher specific growth and xylose uptake rates, respectively, than that of native strain. Moreover, the short lag phase was also observed on adapted strain. During batch fermentation with xylose concentration of 30 g l{sup −1}, K. marxianus NIRE-K3.1 could utilize about 96% of xylose in 72 h and produced 4.67 and 15.7 g l{sup −1} of ethanol and xylitol, respectively, which were 9.72- and 4.63-fold higher than that of native strain. Similarly, specific sugar consumption rate, xylitol, and ethanol yields were 5.07-, 1.15-, and 2.44-fold higher as compared to the native strain, respectively. The results obtained after evolutionary adaptation of K. marxianus NIRE-K3 show the significant improvement in the xylose utilization, ethanol and xylitol yields, and productivities. By understanding the results obtained, the significance of evolutionary adaptation has been rationalized, since the adapted culture could be more stable and could enhance the productivity.

  15. Pichia stipitis xylose reductase helps detoxifying lignocellulosic hydrolysate by reducing 5-hydroxymethyl-furfural (HMF

    Directory of Open Access Journals (Sweden)

    Röder Anja

    2008-06-01

    Full Text Available Abstract Background Pichia stipitis xylose reductase (Ps-XR has been used to design Saccharomyces cerevisiae strains that are able to ferment xylose. One example is the industrial S. cerevisiae xylose-consuming strain TMB3400, which was constructed by expression of P. stipitis xylose reductase and xylitol dehydrogenase and overexpression of endogenous xylulose kinase in the industrial S. cerevisiae strain USM21. Results In this study, we demonstrate that strain TMB3400 not only converts xylose, but also displays higher tolerance to lignocellulosic hydrolysate during anaerobic batch fermentation as well as 3 times higher in vitro HMF and furfural reduction activity than the control strain USM21. Using laboratory strains producing various levels of Ps-XR, we confirm that Ps-XR is able to reduce HMF both in vitro and in vivo. Ps-XR overexpression increases the in vivo HMF conversion rate by approximately 20%, thereby improving yeast tolerance towards HMF. Further purification of Ps-XR shows that HMF is a substrate inhibitor of the enzyme. Conclusion We demonstrate for the first time that xylose reductase is also able to reduce the furaldehyde compounds that are present in undetoxified lignocellulosic hydrolysates. Possible implications of this newly characterized activity of Ps-XR on lignocellulosic hydrolysate fermentation are discussed.

  16. Metabolic Engineering of Escherichia coli K12 for Homofermentative Production of L-Lactate from Xylose.

    Science.gov (United States)

    Jiang, Ting; Zhang, Chen; He, Qin; Zheng, Zhaojuan; Ouyang, Jia

    2018-02-01

    The efficient utilization of xylose is regarded as a technical barrier to the commercial production of bulk chemicals from biomass. Due to the desirable mechanical properties of polylactic acid (PLA) depending on the isomeric composition of lactate, biotechnological production of lactate with high optical pure has been increasingly focused in recent years. The main objective of this work was to construct an engineered Escherichia coli for the optically pure L-lactate production from xylose. Six chromosomal deletions (pflB, ldhA, ackA, pta, frdA, adhE) and a chromosomal integration of L-lactate dehydrogenase-encoding gene (ldhL) from Bacillus coagulans was involved in construction of E. coli KSJ316. The recombinant strain could produce L-lactate from xylose resulting in a yield of 0.91 g/g xylose. The chemical purity of L-lactate was 95.52%, and the optical purity was greater than 99%. Moreover, three strategies, including overexpression of L-lactate dehydrogenase, intensification of xylose catabolism, and addition of additives to medium, were designed to enhance the production. The results showed that they could increase the concentration of L-lactate by 32.90, 20.13, and 233.88% relative to the control, respectively. This was the first report that adding formate not only could increase the xylose utilization but also led to the fewer by-product levels.

  17. The effect of Streptococcus mutans and Candida glabrata on Candida albicans biofilms formed on different surfaces

    NARCIS (Netherlands)

    Pereira-Cenci, T.; Deng, D.M.; Kraneveld, E.A.; Manders, E.M.M.; Del Bel Cury, A.A.; ten Cate, J.M.; Crielaard, W.

    2008-01-01

    Although Candida containing biofilms contribute to the development of oral candidosis, the characteristics of multi-species Candida biofilms and how oral bacteria modulate these biofilms is poorly understood. The aim of this study was to investigate interactions between Candida albicans and either

  18. [Distribution of Candida species in vaginal specimens and evaluation of CHROMagar Candida medium].

    Science.gov (United States)

    Gültekin, Berna; Yazici, Vesile; Aydin, Neriman

    2005-07-01

    Identification of Candida species is important to guide treatment in vulvovaginal candidiasis which is seen frequently and needs long-term therapy due to recurrence. The aim of this study was to determine the species distribution of Candida isolated from vaginal specimens and evaluation of CHROMagar Candida medium in the laboratory diagnosis. Samples from 80 patients who were clinically diagnosed as vaginitis have been analysed in our laboratory. Colonies appeared on CHROMagar Candida media after 48 hours of incubation at 35 degrees C were evaluated for their colors and characteristics. Candida strains were identified by germ tube test, growth on corn meal Tween 80 agar and when necessary also by API 20 C AUX commercial kit. A total of 84 Candida strains were isolated from 80 patients. Two different Candida species have been isolated from four (5%) of the samples. Among Candida strains isolated, 45 (53.6%) were C. albicans, 29 (34.5%) C. glabrata, 7 (8.3%) C. krusei, and 3 (3.6%) C. kefyr. All of the C. albicans and six of the seven C. krusei isolates have been identified correctly by CHROMagar Candida medium. These results showed that C. albicans is still the most frequently isolated species from vaginal samples. It was concluded that CHROMagar Candida medium is useful for identification of colonies due to frequently seen Candida species and also in differentiation of multiple Candida species grown on the same culture.

  19. Candida Biofilms: Threats, Challenges, and Promising Strategies

    Science.gov (United States)

    Cavalheiro, Mafalda; Teixeira, Miguel Cacho

    2018-01-01

    Candida species are fungal pathogens known for their ability to cause superficial and systemic infections in the human host. These pathogens are able to persist inside the host due to the development of pathogenicity and multidrug resistance traits, often leading to the failure of therapeutic strategies. One specific feature of Candida species pathogenicity is their ability to form biofilms, which protects them from external factors such as host immune system defenses and antifungal drugs. This review focuses on the current threats and challenges when dealing with biofilms formed by Candida albicans, Candida glabrata, Candida tropicalis, and Candida parapsilosis, highlighting the differences between the four species. Biofilm characteristics depend on the ability of each species to produce extracellular polymeric substances (EPS) and display dimorphic growth, but also on the biofilm substratum, carbon source availability and other factors. Additionally, the transcriptional control over processes like adhesion, biofilm formation, filamentation, and EPS production displays great complexity and diversity within pathogenic yeasts of the Candida genus. These differences not only have implications in the persistence of colonization and infections but also on antifungal resistance typically found in Candida biofilm cells, potentiated by EPS, that functions as a barrier to drug diffusion, and by the overexpression of drug resistance transporters. The ability to interact with different species in in vivo Candida biofilms is also a key factor to consider when dealing with this problem. Despite many challenges, the most promising strategies that are currently available or under development to limit biofilm formation or to eradicate mature biofilms are discussed. PMID:29487851

  20. Candida Biofilms: Threats, Challenges, and Promising Strategies.

    Science.gov (United States)

    Cavalheiro, Mafalda; Teixeira, Miguel Cacho

    2018-01-01

    Candida species are fungal pathogens known for their ability to cause superficial and systemic infections in the human host. These pathogens are able to persist inside the host due to the development of pathogenicity and multidrug resistance traits, often leading to the failure of therapeutic strategies. One specific feature of Candida species pathogenicity is their ability to form biofilms, which protects them from external factors such as host immune system defenses and antifungal drugs. This review focuses on the current threats and challenges when dealing with biofilms formed by Candida albicans, Candida glabrata, Candida tropicalis , and Candida parapsilosis , highlighting the differences between the four species. Biofilm characteristics depend on the ability of each species to produce extracellular polymeric substances (EPS) and display dimorphic growth, but also on the biofilm substratum, carbon source availability and other factors. Additionally, the transcriptional control over processes like adhesion, biofilm formation, filamentation, and EPS production displays great complexity and diversity within pathogenic yeasts of the Candida genus. These differences not only have implications in the persistence of colonization and infections but also on antifungal resistance typically found in Candida biofilm cells, potentiated by EPS, that functions as a barrier to drug diffusion, and by the overexpression of drug resistance transporters. The ability to interact with different species in in vivo Candida biofilms is also a key factor to consider when dealing with this problem. Despite many challenges, the most promising strategies that are currently available or under development to limit biofilm formation or to eradicate mature biofilms are discussed.

  1. Dynamic metabolomics differentiates between carbon and energy starvation in recombinant Saccharomyces cerevisiae fermenting xylose

    Directory of Open Access Journals (Sweden)

    Bergdahl Basti

    2012-05-01

    Full Text Available Abstract Background The concerted effects of changes in gene expression due to changes in the environment are ultimately reflected in the metabolome. Dynamics of metabolite concentrations under a certain condition can therefore give a description of the cellular state with a high degree of functional information. We used this potential to evaluate the metabolic status of two recombinant strains of Saccharomyces cerevisiae during anaerobic batch fermentation of a glucose/xylose mixture. Two isogenic strains were studied, differing only in the pathways used for xylose assimilation: the oxidoreductive pathway with xylose reductase (XR and xylitol dehydrogenase (XDH or the isomerization pathway with xylose isomerase (XI. The isogenic relationship between the two strains ascertains that the observed responses are a result of the particular xylose pathway and not due to unknown changes in regulatory systems. An increased understanding of the physiological state of these strains is important for further development of efficient pentose-utilizing strains for bioethanol production. Results Using LC-MS/MS we determined the dynamics in the concentrations of intracellular metabolites in central carbon metabolism, nine amino acids, the purine nucleotides and redox cofactors. The general response to the transition from glucose to xylose was increased concentrations of amino acids and TCA-cycle intermediates, and decreased concentrations of sugar phosphates and redox cofactors. The two strains investigated had significantly different uptake rates of xylose which led to an enhanced response in the XI-strain. Despite the difference in xylose uptake rate, the adenylate energy charge remained high and stable around 0.8 in both strains. In contrast to the adenylate pool, large changes were observed in the guanylate pool. Conclusions The low uptake of xylose by the XI-strain led to several distinguished responses: depletion of key metabolites in glycolysis and NADPH

  2. Effects of alumina refinery wastewater and signature metal constituents at the upper thermal tolerance of: 2. The early life stages of the coral Acropora tenuis

    International Nuclear Information System (INIS)

    Negri, Andrew P.; Harford, Andrew J.; Parry, David L.; Dam, Rick A. van

    2011-01-01

    Research highlights: →Methodology to assess relevant toxicants to sensitive early life histories of coral. → Explored the thermal sensitivity of fertilisation and larval metamorphosis in a coral. → First study to identify IC 50 s for Al, Ga and V in corals (at summer temperature). → First study to test the effects of an alumina outfall wastewater on coral. → Found additive effects of wastewater and high SST on fertilisation and metamorphosis. - Abstract: The success of early life history transitions of the coral Acropora tenuis were used as endpoints to evaluate thermal stress and the effects of wastewater discharged to a tropical marine environment. The studies assessed the effects of: (i) temperature; (ii) three signature metals of the wastewater, aluminium (Al), vanadium (V) and gallium (Ga); and (iii) the wastewater (at 27 o C and 32 o C) on fertilisation and larval metamorphosis. The median inhibition temperatures for fertilisation and metamorphosis were 32.8 o C and 33.0 o C, respectively. Fertilisation IC 50 s for Al, V and Ga were 2997, 2884 and 3430 μg L -1 , respectively. Metamorphosis IC 50 s for Al, V and Ga were 1945, 675 and 3566 μg L -1 , respectively. The wastewater only affected fertilisation and metamorphosis at moderate concentrations (IC 50 s = 63% and 67%, v/v, respectively, at 27 o C), posing a low risk to this species in the field. The effects of wastewater and temperature on fertilisation and metamorphosis were additive.

  3. Partial oxidation of D-xylose to maleic anhydride and acrylic acid over vanadyl pyrophosphate

    International Nuclear Information System (INIS)

    Ghaznavi, Touraj; Neagoe, Cristian; Patience, Gregory S.

    2014-01-01

    Xylose is the second most abundant sugar after glucose. Despite its tremendous potential to serve as a renewable feedstock, few commercial processes exploit this resource. Here, we report a new technology in which a two-fluid nozzle atomizes a xylose-water solution into a capillary fluidized bed operating above 300 °C. Xylose-water droplets form at the tip of the injector, vaporize then react with a heterogeneous mixed oxide catalyst. A syringe pump metered the solution to the reactor charged with 1 g of catalyst. Product yield over vanadyl pyrophosphate was higher compared to molybdenum trioxide-cobalt oxide and iron molybdate; it reached 25% for maleic anhydride, 17% for acrylic acid and 11% for acrolein. Gas residence time was 0.2 s. The catalyst was free of coke even after operating for 4 h – based on a thermogravimetric analysis of catalyst withdrawn from the reactor. Below 300 °C, powder agglomerated at the tip of the injector at 300 °C; it also agglomerated with a xylose mass fraction of 7% in water. - Highlights: • D-xylose reacts to form maleic anhydride and acrylic acid above 250 °C. • Vanadyl pyrophosphate is both active and selective for maleic and acrylic acid. • Acid and acrolein yield approaches 50% for a xylose mass fraction of 3% in water. • Catalyst agglomerates at low temperatures and high xylose aqueous mass fraction. • Atomization quality is a determining factor to minimize agglomeration

  4. Detection and antifungal susceptibility testing of oral Candida dubliniensis from human immunodeficiency virus-infected patients

    Directory of Open Access Journals (Sweden)

    Chunchanur Sneha

    2009-10-01

    Full Text Available Context: Candida dubliniensis, an opportunistic yeast that has been implicated in oropharyngeal candidiasis (OPC in patients infected with Human Immunodeficiency Virus (HIV may be under-reported due to its similarity with Candida albicans. Resistance to Fluconazole is often seen in C. dubliniensis isolates from clinical specimens. Aims: To know the prevalence of C. dubliniensis in OPC in patients infected with HIV and their antifungal susceptibility pattern. Settings and Design: One hundred and thirty-two HIV seropositive individuals and 50 healthy controls were included in the study. Materials and Methods: Two oral swabs were collected from the site of the lesion from 132 HIV-infected patients. Oral rinse was obtained from 50 healthy controls. Samples were inoculated on Sabouraud′s dextrose agar (SDA medium and on HiCrome Candida Differential Agar (CHROM agar medium. Isolates were speciated by standard tests. Dark green-colored, germ tube positive isolates, which failed to grow at 420C and negative for xylose assimilation were identified as C. dubliniensis. Antifungal susceptibility test was performed by Macro broth dilution technique (National Committee for Clinical Laboratory Standards guidelines. Results and Conclusions: From 132 patients, 22 (16.3% C. dubliniensis were isolated; samples from healthy controls did not reveal their presence. Antifungal susceptibility test showed higher resistance among C. dubliniensis isolates to azoles compared to C. albicans. Five (22.7% isolates of C. dubliniensis were resistant to Fluconazole followed by four (18.2% to Ketoconazole. This study emphasizes the importance of identification and antifungal susceptibility testing of C. dubliniensis in HIV-infected patients.

  5. Identification of Candida species by PCR and restriction fragment length polymorphism analysis of intergenic spacer regions of ribosomal DNA.

    OpenAIRE

    Williams, D W; Wilson, M J; Lewis, M A; Potts, A J

    1995-01-01

    The PCR was used to amplify a targeted region of the ribosomal DNA from 84 Candida isolates. Unique product sizes were obtained for Candida guilliermondii, Candida (Torulopsis) glabrata, and Candida pseudotropicalis. Isolates of Candida albicans, Candida tropicalis, Candida stellatoidea, Candida parapsilosis, and Candida krusei could be identified following restriction digestion of the PCR products.

  6. Production of 3-hydroxypropionic acid from glucose and xylose by metabolically engineered Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Kanchana R. Kildegaard

    2015-12-01

    Full Text Available Biomass, the most abundant carbon source on the planet, may in the future become the primary feedstock for production of fuels and chemicals, replacing fossil feedstocks. This will, however, require development of cell factories that can convert both C6 and C5 sugars present in lignocellulosic biomass into the products of interest. We engineered Saccharomyces cerevisiae for production of 3-hydroxypropionic acid (3HP, a potential building block for acrylates, from glucose and xylose. We introduced the 3HP biosynthetic pathways via malonyl-CoA or β-alanine intermediates into a xylose-consuming yeast. Using controlled fed-batch cultivation, we obtained 7.37±0.17 g 3HP L−1 in 120 hours with an overall yield of 29±1% Cmol 3HP Cmol−1 xylose. This study is the first demonstration of the potential of using S. cerevisiae for production of 3HP from the biomass sugar xylose. Keywords: Metabolic engineering, Biorefineries, 3-hydroxypropionic acid, Saccharomyces cerevisiae, Xylose utilization

  7. Efficient fermentation of xylose to ethanol at high formic acid concentrations by metabolically engineered Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Hasunuma, Tomohisa; Yoshimura, Kazuya; Matsuda, Fumio [Kobe Univ., Hyogo (Japan). Organization of Advanced Science and Technology; Sung, Kyung-mo; Sanda, Tomoya; Kondo, Akihiko [Kobe Univ., Hyogo (Japan). Dept. of Chemical Science and Engineering

    2011-05-15

    Recombinant yeast strains highly tolerant to formic acid during xylose fermentation were constructed. Microarray analysis of xylose-fermenting Saccharomyces cerevisiae strain overexpressing endogenous xylulokinase in addition to xylose reductase and xylitol dehydrogenase from Pichia stipitis revealed that upregulation of formate dehydrogenase genes (FDH1 and FDH2) was one of the most prominent transcriptional events against excess formic acid. The quantification of formic acid in medium indicated that the innate activity of FDH was too weak to detoxify formic acid. To reinforce the capability for formic acid breakdown, the FDH1 gene was additionally overexpressed in the xylose-metabolizing recombinant yeast. This modification allowed the yeast to rapidly decompose excess formic acid. The yield and final ethanol concentration in the presence of 20 mM formic acid is as essentially same as that of control. The fermentation profile also indicated that the production of xylitol and glycerol, major by-products in xylose fermentation, was not affected by the upregulation of FDH activity. (orig.)

  8. Xylose-fermenting Pichia stipitis by genome shuffling for improved ethanol production.

    Science.gov (United States)

    Shi, Jun; Zhang, Min; Zhang, Libin; Wang, Pin; Jiang, Li; Deng, Huiping

    2014-03-01

    Xylose fermentation is necessary for the bioconversion of lignocellulose to ethanol as fuel, but wild-type Saccharomyces cerevisiae strains cannot fully metabolize xylose. Several efforts have been made to obtain microbial strains with enhanced xylose fermentation. However, xylose fermentation remains a serious challenge because of the complexity of lignocellulosic biomass hydrolysates. Genome shuffling has been widely used for the rapid improvement of industrially important microbial strains. After two rounds of genome shuffling, a genetically stable, high-ethanol-producing strain was obtained. Designated as TJ2-3, this strain could ferment xylose and produce 1.5 times more ethanol than wild-type Pichia stipitis after fermentation for 96 h. The acridine orange and propidium iodide uptake assays showed that the maintenance of yeast cell membrane integrity is important for ethanol fermentation. This study highlights the importance of genome shuffling in P. stipitis as an effective method for enhancing the productivity of industrial strains. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  9. Increased ethanol production by deletion of HAP4 in recombinant xylose-assimilating Saccharomyces cerevisiae.

    Science.gov (United States)

    Matsushika, Akinori; Hoshino, Tamotsu

    2015-12-01

    The Saccharomyces cerevisiae HAP4 gene encodes a transcription activator that plays a key role in controlling the expression of genes involved in mitochondrial respiration and reductive pathways. This work examines the effect of knockout of the HAP4 gene on aerobic ethanol production in a xylose-utilizing S. cerevisiae strain. A hap4-deleted recombinant yeast strain (B42-DHAP4) showed increased maximum concentration, production rate, and yield of ethanol compared with the reference strain MA-B42, irrespective of cultivation medium (glucose, xylose, or glucose/xylose mixtures). Notably, B42-DHAP4 was capable of producing ethanol from xylose as the sole carbon source under aerobic conditions, whereas no ethanol was produced by MA-B42. Moreover, the rate of ethanol production and ethanol yield (0.44 g/g) from the detoxified hydrolysate of wood chips was markedly improved in B42-DHAP4 compared to MA-B42. Thus, the results of this study support the view that deleting HAP4 in xylose-utilizing S. cerevisiae strains represents a useful strategy in ethanol production processes.

  10. Growth of Candida albicans hyphae.

    Science.gov (United States)

    Sudbery, Peter E

    2011-08-16

    The fungus Candida albicans is often a benign member of the mucosal flora; however, it commonly causes mucosal disease with substantial morbidity and in vulnerable patients it causes life-threatening bloodstream infections. A striking feature of its biology is its ability to grow in yeast, pseudohyphal and hyphal forms. The hyphal form has an important role in causing disease by invading epithelial cells and causing tissue damage. This Review describes our current understanding of the network of signal transduction pathways that monitors environmental cues to activate a programme of hypha-specific gene transcription, and the molecular processes that drive the highly polarized growth of hyphae.

  11. Performance of chromogenic media for Candida in rapid presumptive identification of Candida species from clinical materials.

    Science.gov (United States)

    Pravin Charles, M V; Kali, Arunava; Joseph, Noyal Mariya

    2015-06-01

    In perspective of the worldwide increase in a number of immunocompromised patients, the need for identification of Candida species has become a major concern. The development of chromogenic differential media, introduced recently, facilitate rapid speciation. However, it can be employed for routine mycology workup only after an exhaustive evaluation of its benefit and cost effectiveness. This study was undertaken to evaluate the benefit and cost effectiveness of chromogenic media for speciation of Candida clinical isolates. Sputum samples of 382 patients were screened for the presence of Candida spp. by Gram stain and culture on sabouraud dextrose agar. Candida species were identified using Gram stain morphology, germ tube formation, cornmeal agar with Tween-80, sugar fermentation tests and morphology on HiCrome Candida differential agar. All the Candida isolates were inoculated on HiCrome Candida agar (HiMedia, Mumbai, India). The sensitivity and specificity of HiCrome agar for identification of Candida albicans were 90% and 96.42%, respectively whereas sensitivity and specificity of carbohydrate fermentation test were 86.67% and 74.07%, respectively. Sensitivity and specificity values of HiCrome agar for detection of C. albicans, Candida parapsilosis and Candida glabrata were above 90%. We found HiCrome agar has high sensitivity and specificity comparable to that of the conventional method. In addition, use of this differential media could significantly cut down the turnaround time as well as cost of sample processing.

  12. Multi-species biofilm of Candida albicans and non-Candida albicans Candida species on acrylic substrate

    Directory of Open Access Journals (Sweden)

    Apurva K Pathak

    2012-02-01

    Full Text Available OBJECTIVE: In polymicrobial biofilms bacteria extensively interact with Candida species, but the interaction among the different species of the Candida is yet to be completely evaluated. In the present study, the difference in biofilm formation ability of clinical isolates of four species of Candida in both single-species and multi-species combinations on the surface of dental acrylic resin strips was evaluated. MATERIAL AND METHODS: The species of Candida, isolated from multiple species oral candidiasis of the neutropenic patients, were used for the experiment. Organisms were cultured on Sabouraud dextrose broth with 8% glucose (SDB. Biofilm production on the acrylic resins strips was determined by crystal violet assay. Student's t-test and ANOVA were used to compare in vitro biofilm formation for the individual species of Candida and its different multi-species combinations. RESULTS: In the present study, differences between the mean values of the biofilm-forming ability of individual species (C. glabrata>C. krusei>C. tropicalis>C. albicans and in its multi-species' combinations (the highest for C. albicans with C. glabrata and the lowest for all the four species combination were reported. CONCLUSIONS: The findings of this study showed that biofilm-forming ability was found greater for non-Candida albicans Candida species (NCAC than for C. albicans species with intra-species variation. Presence of C. albicans in multi-species biofilms increased, whereas; C. tropicalis decreased the biofilm production with all other NCAC species.

  13. Simple low cost differentiation of Candida auris from Candida haemulonii complex using CHROMagar Candida medium supplemented with Pal's medium.

    Science.gov (United States)

    Kumar, Anil; Sachu, Arun; Mohan, Karthika; Vinod, Vivek; Dinesh, Kavitha; Karim, Shamsul

    Candida auris is unique due to its multidrug resistance and misidentification as Candida haemulonii by commercial systems. Its correct identification is important to avoid inappropriate treatments. To develop a cheap method for differentiating C. auris from isolates identified as C. haemulonii by VITEK2. Fifteen C. auris isolates, six isolates each of C. haemulonii and Candida duobushaemulonii, and one isolate of Candida haemulonii var. vulnera were tested using CHROMagar Candida medium supplemented with Pal's agar for better differentiation. On CHROMagar Candida medium supplemented with Pal's agar all C. auris strains showed confluent growth of white to cream colored smooth colonies at 37°C and 42°C after 24 and 48h incubation and did not produce pseudohyphae. The isolates of the C. haemulonii complex, on the contrary, showed poor growth of smooth, light-pink colonies at 24h while at 48h the growth was semiconfluent with the production of pseudohyphae. C. haemulonii complex failed to grow at 42°C. We report a rapid and cheap method using CHROMagar Candida medium supplemented with Pal's agar for differentiating C. auris from isolates identified as C. haemulonii by VITEK2. Copyright © 2017 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

  14. Portrait of Candida Species Biofilm Regulatory Network Genes.

    Science.gov (United States)

    Araújo, Daniela; Henriques, Mariana; Silva, Sónia

    2017-01-01

    Most cases of candidiasis have been attributed to Candida albicans, but Candida glabrata, Candida parapsilosis and Candida tropicalis, designated as non-C. albicans Candida (NCAC), have been identified as frequent human pathogens. Moreover, Candida biofilms are an escalating clinical problem associated with significant rates of mortality. Biofilms have distinct developmental phases, including adhesion/colonisation, maturation and dispersal, controlled by complex regulatory networks. This review discusses recent advances regarding Candida species biofilm regulatory network genes, which are key components for candidiasis. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Selective Preparation of Furfural from Xylose over Sulfonic Acid Functionalized Mesoporous Sba-15 Materials

    Directory of Open Access Journals (Sweden)

    Panpan Li

    2011-04-01

    Full Text Available Sulfonic acid functionalized mesoporous SBA-15 materials were prepared using the co-condensation and grafting methods, respectively, and their catalytic performance in the dehydration of xylose to furfural was examined. SBA-15-SO3H(C prepared by the co-condensation method showed 92–95% xylose conversion and 74% furfural selectivity, and 68–70% furfural yield under the given reaction conditions. The deactivation and regeneration of the SBA-15-SO3H(C catalyst for the dehydration of xylose was also investigated. The results indicate that the used and regeneration catalysts retained the SBA-15 mesoporous structure, and the S content of SBA-15-SO3H(C almost did not change. The deactivation of the catalysts is proposed to be associated with the accumulation of byproducts, which is caused by the loss reaction of furfural. After regeneration by H2O2, the catalytic activity of the catalyst almost recovered.

  16. Improved inhibitor tolerance in xylose-fermenting yeast Spathaspora passalidarum by mutagenesis and protoplast fusion

    DEFF Research Database (Denmark)

    Hou, Xiaoru; Yao, Shuo

    2012-01-01

    The xylose-fermenting yeast Spathaspora passalidarum showed excellent fermentation performance utilizing glucose and xylose under anaerobic conditions. But this yeast is highly sensitive to the inhibitors such as furfural present in the pretreated lignocellulosic biomass. In order to improve...... from fusion of the protoplasts of S. passalidarum M7 and a robust yeast, Saccharomyces cerevisiae ATCC 96581, were able to grow in 75% WSLQ and produce around 0.4 g ethanol/g consumed xylose. Among the selected hybrid strains, the hybrid FS22 showed the best fermentation capacity in 75% WSLQ...... the inhibitor tolerance of this yeast, a combination of UV mutagenesis and protoplast fusion was used to construct strains with improved performance. Firstly, UVinduced mutants were screened and selected for improved tolerance towards furfural. The most promised mutant, S. passalidarum M7, produced 50% more...

  17. Bioethanol Production From Cellulose by Candida tropicalis, as An Alternative Microbial Agent to Produce Ethanol from Lignocellulosic Biomass

    Directory of Open Access Journals (Sweden)

    Hermansyah

    2016-04-01

    Full Text Available Abstract: Candida tropicalis isolated from Tuak is a potentially useful microorganism for the ethanol production from lignocellulosic biomass and it can be alterbative agent replacing Saccharomyces cerevisae for fermentation process. Although C.tropicalis could not convert all carbohydrates content of lignocellulosic into bioethanol, however it is able to grow on medium in the presence of either xylose or arabinose as carbon source. Our result showed that fermentation of 10 % (w/v cellulosic as sole carbon source produced 2.88% (v/v ethanol by C.tropicalis. This ethanol production was lower than usage of 10% (w/v dextrose as sole carbon source medium which producing 5.51% (v/v ethanol. Based upon our expreiment indicated that C.tropicalis is able to conduct two main process in converting of cellulosic material- to ethanol which is hydrolysis the degradation of cellulose into glucose, and fermentation the process the conversion glucose into bioethanol. Keywords : Candida tropicalis, bioethanol, fermentation, cellulosic Abstrak (Indonesian: Candida tropicalis yang diisiolasi dari Tuak adalah agen yang berpotensi dalam produksi etanol dari biomasa lignoselulosa dan dapat dijadikan agen alternatif menggantikan Saccharomyces cerevisiae pada proses fernentasi. Walaupun C.tropicalis tidak dapat mengkonversi semua kandungan karbohidrat lignoselulosamenjadi etanol, akan tetapi C.tropicalis mampu tumbuh pada media dengan xilosa atau arabinosa sebagaisumber karbon. Hasil kami menunjukkan bahwa dengan mengguankan C.tropicalis fermentasi 10% (w/v selulosa sebagai satu-satunya sumber karbon menghasilkan 2,88% (v/v etanol, Produksi etanol ini lebih rendah jika menggunakan 10% (w/v dekstrosa sebagai satu satunya sumber karbon yang menghasilkan 5,51% (v/v etanol. Berdasarkan percobaan menunjukkan bahwa C.tropicalis mampu melakukan dua proses utama dalam mengkonversi material selulosa menjadi etanol yaitu hidrolisis degradasi selulosa menjadi glukosa, dan

  18. Radiation resistance of Candida parapsilosis

    International Nuclear Information System (INIS)

    Kristensen, H.

    1982-01-01

    The radiation resistance of 30 strains classified as Candida parapsilosis was examined. The strains originated partly from environments where ionizing radiation was used for research or routine purposes, partly from environments with no known possibility for selection of strains with unusually high radiation resistance. D-6 values between 1.5 and 2.4 Megarads were found when the cells were irradiated in the dried state, a D-6 value being the dose necessary to reduce the initial number of colony-forming units with a factor of 10 6 . The majority of D-6 values were between 1.9 and 2.1 Megarads. D-6 values for the cells irradiated in liquid media were about 2/3 of tose in the dried state. No difference in resistance was revealed depending on the origin of the strains examined. For radiation sterilization of medical products the demonstrated resistance of Candida parapsilosis might be of importance of routine use of minimum doses below 2.5 Megarads were to be accepted. (author)

  19. Tandem mass spectrometric characterization of the conversion of xylose to furfural

    International Nuclear Information System (INIS)

    Vinueza, Nelson R.; Kim, Eurick S.; Gallardo, Vanessa A.; Mosier, Nathan S.; Abu-Omar, Mahdi M.; Carpita, Nicholas C.; Kenttämaa, Hilkka I.

    2015-01-01

    Thermal decomposition of xylose into furfural under acidic conditions has been studied using tandem mass spectrometry. Two different Brønsted acids, maleic and sulfuric acids, were used to demonstrate that varying the Brønsted acid does not affect the mechanism of the reaction. Two selectively labeled xylose molecules, 1- 13 C and 5- 13 C-xyloses, were examined to determine which carbon atom is converted to the aldehyde carbon in furfural. This can be done by using tandem mass spectrometry since collision-activated dissociation (CAD) of protonated unlabeled furfural results in the loss of CO from the aldehyde moiety. The loss of a neutral molecule with MW of 29 Da ( 13 CO) was observed for protonated furfural derived from 1- 13 C-labeled xylose while the loss of a neutral molecule with MW of 28 Da (CO) was observed for protonated furfural derived from 5- 13 C labeled xylose. These results support the hypothesis that the mechanism of formation of furfural under mildly hot acidic conditions involves an intramolecular rearrangement of protonated xylose into the pyranose form rather than into an open-chain form. - Highlights: • Mechanism of catalytic conversion of Xyl to furfural under acidic conditions was studied by MS/MS and partially labeled Xyl. • The type of acid does not have a strong influence on the mechanism of catalytic conversion of Xyl to furfural. • The mechanism of formation of furfural under mildly hot acidic conditions involves an intramolecular rearrangement of Xyl

  20. Influence of genetic background of engineered xylose-fermenting industrial Saccharomyces cerevisiae strains for ethanol production from lignocellulosic hydrolysates

    Science.gov (United States)

    An industrial ethanol-producing Saccharomyces cerevisiae strain with genes needed for xylose-fermentation integrated into its genome was used to obtain haploids and diploid isogenic strains. The isogenic strains were more effective in metabolizing xylose than their parental strain (p < 0.05) and abl...

  1. Co-utilization of L-arabinose and D-xylose by laboratory and industrial Saccharomyces cerevisiae strains

    Directory of Open Access Journals (Sweden)

    Boles Eckhard

    2006-04-01

    Full Text Available Abstract Background Fermentation of lignocellulosic biomass is an attractive alternative for the production of bioethanol. Traditionally, the yeast Saccharomyces cerevisiae is used in industrial ethanol fermentations. However, S. cerevisiae is naturally not able to ferment the pentose sugars D-xylose and L-arabinose, which are present in high amounts in lignocellulosic raw materials. Results We describe the engineering of laboratory and industrial S. cerevisiae strains to co-ferment the pentose sugars D-xylose and L-arabinose. Introduction of a fungal xylose and a bacterial arabinose pathway resulted in strains able to grow on both pentose sugars. Introduction of a xylose pathway into an arabinose-fermenting laboratory strain resulted in nearly complete conversion of arabinose into arabitol due to the L-arabinose reductase activity of the xylose reductase. The industrial strain displayed lower arabitol yield and increased ethanol yield from xylose and arabinose. Conclusion Our work demonstrates simultaneous co-utilization of xylose and arabinose in recombinant strains of S. cerevisiae. In addition, the co-utilization of arabinose together with xylose significantly reduced formation of the by-product xylitol, which contributed to improved ethanol production.

  2. KINETICS OF GROWTH AND ETHANOL PRODUCTION ON DIFFERENT CARBON SUBSTRATES USING GENETICALLY ENGINEERED XYLOSE-FERMENTING YEAST

    Science.gov (United States)

    Saccharomyces cerevisiae 424A (LNH-ST) strain was used for fermentation of glucose and xylose. Growth kinetics and ethanol productivity were calculated for batch fermentation on media containing different combinations of glucose and xylose to give a final sugar concentra...

  3. Improved Xylose Metabolism by a CYC8 Mutant of Saccharomyces cerevisiae.

    Science.gov (United States)

    Nijland, Jeroen G; Shin, Hyun Yong; Boender, Leonie G M; de Waal, Paul P; Klaassen, Paul; Driessen, Arnold J M

    2017-06-01

    Engineering Saccharomyces cerevisiae for the utilization of pentose sugars is an important goal for the production of second-generation bioethanol and biochemicals. However, S. cerevisiae lacks specific pentose transporters, and in the presence of glucose, pentoses enter the cell inefficiently via endogenous hexose transporters (HXTs). By means of in vivo engineering, we have developed a quadruple hexokinase deletion mutant of S. cerevisiae that evolved into a strain that efficiently utilizes d-xylose in the presence of high d-glucose concentrations. A genome sequence analysis revealed a mutation (Y353C) in the general corepressor CYC8 , or SSN6 , which was found to be responsible for the phenotype when introduced individually in the nonevolved strain. A transcriptome analysis revealed altered expression of 95 genes in total, including genes involved in (i) hexose transport, (ii) maltose metabolism, (iii) cell wall function (mannoprotein family), and (iv) unknown functions (seripauperin multigene family). Of the 18 known HXTs, genes for 9 were upregulated, especially the low or nonexpressed HXT10 , HXT13 , HXT15 , and HXT16 Mutant cells showed increased uptake rates of d-xylose in the presence of d-glucose, as well as elevated maximum rates of metabolism ( V max ) for both d-glucose and d-xylose transport. The data suggest that the increased expression of multiple hexose transporters renders d-xylose metabolism less sensitive to d-glucose inhibition due to an elevated transport rate of d-xylose into the cell. IMPORTANCE The yeast Saccharomyces cerevisiae is used for second-generation bioethanol formation. However, growth on xylose is limited by pentose transport through the endogenous hexose transporters (HXTs), as uptake is outcompeted by the preferred substrate, glucose. Mutant strains were obtained with improved growth characteristics on xylose in the presence of glucose, and the mutations mapped to the regulator Cyc8. The inactivation of Cyc8 caused increased

  4. Increasing ethanol productivity during xylose fermentation by cell recycling of recombinant Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Roca, Christophe Francois Aime; Olsson, Lisbeth

    2003-01-01

    The influence of cell recycling of xylose-fermenting Saccharomyces cerevisiae TMB3001 was investigated during continuous cultivation on a xylose-glucose mixture. By using cell recycling at the dilution rate (D) of 0.05 h(-1), the cell-mass concentration could be increased from 2.2 g l(-1) to 22 g l...... ethanol productivity was in the range of 0.23-0.26 g g(-1) h(-1) with or without cell recycling, showing that an increased cell-mass concentration did not influence the efficiency of the yeast....

  5. Benzoate-induced stress enhances xylitol yield in aerobic fed-batch culture of Candida mogii TISTR 5892.

    Science.gov (United States)

    Wannawilai, Siwaporn; Sirisansaneeyakul, Sarote; Chisti, Yusuf

    2015-01-20

    Production of the natural sweetener xylitol from xylose via the yeast Candida mogii TISTR 5892 was compared with and without the growth inhibitor sodium benzoate in the culture medium. Sodium benzoate proved to be an uncompetitive inhibitor in relatively poorly oxygenated shake flask aerobic cultures. In a better controlled aerobic environment of a bioreactor, the role of sodium benzoate could equally well be described as competitive, uncompetitive or noncompetitive inhibitor of growth. In intermittent fed-batch fermentations under highly aerobic conditions, the presence of sodium benzoate at 0.15gL(-1) clearly enhanced the xylitol titer relative to the control culture without the sodium benzoate. The final xylitol concentration and the average xylitol yield on xylose were nearly 50gL(-1) and 0.57gg(-1), respectively, in the presence of sodium benzoate. Both these values were substantially higher than reported for the same fermentation under microaerobic conditions. Therefore, a fed-batch aerobic fermentation in the presence of sodium benzoate is promising for xylitol production using C. mogii. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Azole Antifungal Resistance in Candida albicans and Emerging Non-albicans Candida Species

    Science.gov (United States)

    Whaley, Sarah G.; Berkow, Elizabeth L.; Rybak, Jeffrey M.; Nishimoto, Andrew T.; Barker, Katherine S.; Rogers, P. David

    2017-01-01

    Within the limited antifungal armamentarium, the azole antifungals are the most frequent class used to treat Candida infections. Azole antifungals such as fluconazole are often preferred treatment for many Candida infections as they are inexpensive, exhibit limited toxicity, and are available for oral administration. There is, however, extensive documentation of intrinsic and developed resistance to azole antifungals among several Candida species. As the frequency of azole resistant Candida isolates in the clinical setting increases, it is essential to elucidate the mechanisms of such resistance in order to both preserve and improve upon the azole class of antifungals for the treatment of Candida infections. This review examines azole resistance in infections caused by C. albicans as well as the emerging non-albicans Candida species C. parapsilosis, C. tropicalis, C. krusei, and C. glabrata and in particular, describes the current understanding of molecular basis of azole resistance in these fungal species. PMID:28127295

  7. Candida Biofilms: Threats, Challenges, and Promising Strategies

    Directory of Open Access Journals (Sweden)

    Mafalda Cavalheiro

    2018-02-01

    Full Text Available Candida species are fungal pathogens known for their ability to cause superficial and systemic infections in the human host. These pathogens are able to persist inside the host due to the development of pathogenicity and multidrug resistance traits, often leading to the failure of therapeutic strategies. One specific feature of Candida species pathogenicity is their ability to form biofilms, which protects them from external factors such as host immune system defenses and antifungal drugs. This review focuses on the current threats and challenges when dealing with biofilms formed by Candida albicans, Candida glabrata, Candida tropicalis, and Candida parapsilosis, highlighting the differences between the four species. Biofilm characteristics depend on the ability of each species to produce extracellular polymeric substances (EPS and display dimorphic growth, but also on the biofilm substratum, carbon source availability and other factors. Additionally, the transcriptional control over processes like adhesion, biofilm formation, filamentation, and EPS production displays great complexity and diversity within pathogenic yeasts of the Candida genus. These differences not only have implications in the persistence of colonization and infections but also on antifungal resistance typically found in Candida biofilm cells, potentiated by EPS, that functions as a barrier to drug diffusion, and by the overexpression of drug resistance transporters. The ability to interact with different species in in vivo Candida biofilms is also a key factor to consider when dealing with this problem. Despite many challenges, the most promising strategies that are currently available or under development to limit biofilm formation or to eradicate mature biofilms are discussed.

  8. Oxidative production of xylonic acid using xylose in distillation stillage of cellulosic ethanol fermentation broth by Gluconobacter oxydans.

    Science.gov (United States)

    Zhang, Hongsen; Han, Xushen; Wei, Chengxiang; Bao, Jie

    2017-01-01

    An oxidative production process of xylonic acid using xylose in distillation stillage of cellulosic ethanol fermentation broth was designed, experimentally investigated, and evaluated. Dry dilute acid pretreated and biodetoxified corn stover was simultaneously saccharified and fermented into 59.80g/L of ethanol (no xylose utilization). 65.39g/L of xylose was obtained in the distillation stillage without any concentrating step after ethanol was distillated. Then the xylose was completely converted into 66.42g/L of xylonic acid by Gluconobacter oxydans. The rigorous Aspen Plus modeling shows that the wastewater generation and energy consumption was significantly reduced comparing to the previous xylonic acid production process using xylose in pretreatment liquid. This study provided a practical process option for xylonic acid production from lignocellulose feedstock with significant reduction of wastewater and energy consumption. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Candida albicans osteomyelitis of the cervical spine

    International Nuclear Information System (INIS)

    Cha, Jang-Gyu; Hong, Hyun-Sook; Koh, Yoon-Woo; Kim, Hee-Kyung; Park, Jung-Mi

    2008-01-01

    Fungal osteomyelitis is a rare infection that usually develops in immunocompromised patients. Additionally, involvement of the cervical spine by Candida albicans is extremely rare; only three previous cases of Candida vertebral osteomyelitis have been reported in the literature. The diagnosis may be delayed due to nonspecific radiologic findings and a slow progression. We report the CT, MRI, bone scan, and PET-CT findings in a patient who developed Candida osteomyelitis, which was initially misdiagnosed as metastasis, at the atlas and axis following treatment for nasopharyngeal cancer. (orig.)

  10. Purification and germination of Candida albicans and Candida dubliniensis chlamydospores cultured in liquid media

    OpenAIRE

    Citiulo, Francesco; Moran, Gary; COLEMAN, DAVID; SULLIVAN, DEREK

    2009-01-01

    PUBLISHED Candida albicans and Candida dubliniensis are the only Candida species that have been observed to produce chlamydospores. The function of these large, thick-walled cells is currently unknown. In this report we describe the production and purification of chlamydospores from these species in defined liquid media. Staining with the fluorescent dye FUN-1 indicated that chlamydospores are metabolically active cells, but that metabolic activity is undetectable in chlamydospores that...

  11. Directed Evolution Reveals Unexpected Epistatic Interactions That Alter Metabolic Regulation and Enable Anaerobic Xylose Use by Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Trey K Sato

    2016-10-01

    Full Text Available The inability of native Saccharomyces cerevisiae to convert xylose from plant biomass into biofuels remains a major challenge for the production of renewable bioenergy. Despite extensive knowledge of the regulatory networks controlling carbon metabolism in yeast, little is known about how to reprogram S. cerevisiae to ferment xylose at rates comparable to glucose. Here we combined genome sequencing, proteomic profiling, and metabolomic analyses to identify and characterize the responsible mutations in a series of evolved strains capable of metabolizing xylose aerobically or anaerobically. We report that rapid xylose conversion by engineered and evolved S. cerevisiae strains depends upon epistatic interactions among genes encoding a xylose reductase (GRE3, a component of MAP Kinase (MAPK signaling (HOG1, a regulator of Protein Kinase A (PKA signaling (IRA2, and a scaffolding protein for mitochondrial iron-sulfur (Fe-S cluster biogenesis (ISU1. Interestingly, the mutation in IRA2 only impacted anaerobic xylose consumption and required the loss of ISU1 function, indicating a previously unknown connection between PKA signaling, Fe-S cluster biogenesis, and anaerobiosis. Proteomic and metabolomic comparisons revealed that the xylose-metabolizing mutant strains exhibit altered metabolic pathways relative to the parental strain when grown in xylose. Further analyses revealed that interacting mutations in HOG1 and ISU1 unexpectedly elevated mitochondrial respiratory proteins and enabled rapid aerobic respiration of xylose and other non-fermentable carbon substrates. Our findings suggest a surprising connection between Fe-S cluster biogenesis and signaling that facilitates aerobic respiration and anaerobic fermentation of xylose, underscoring how much remains unknown about the eukaryotic signaling systems that regulate carbon metabolism.

  12. Directed Evolution Reveals Unexpected Epistatic Interactions That Alter Metabolic Regulation and Enable Anaerobic Xylose Use by Saccharomyces cerevisiae.

    Science.gov (United States)

    Sato, Trey K; Tremaine, Mary; Parreiras, Lucas S; Hebert, Alexander S; Myers, Kevin S; Higbee, Alan J; Sardi, Maria; McIlwain, Sean J; Ong, Irene M; Breuer, Rebecca J; Avanasi Narasimhan, Ragothaman; McGee, Mick A; Dickinson, Quinn; La Reau, Alex; Xie, Dan; Tian, Mingyuan; Reed, Jennifer L; Zhang, Yaoping; Coon, Joshua J; Hittinger, Chris Todd; Gasch, Audrey P; Landick, Robert

    2016-10-01

    The inability of native Saccharomyces cerevisiae to convert xylose from plant biomass into biofuels remains a major challenge for the production of renewable bioenergy. Despite extensive knowledge of the regulatory networks controlling carbon metabolism in yeast, little is known about how to reprogram S. cerevisiae to ferment xylose at rates comparable to glucose. Here we combined genome sequencing, proteomic profiling, and metabolomic analyses to identify and characterize the responsible mutations in a series of evolved strains capable of metabolizing xylose aerobically or anaerobically. We report that rapid xylose conversion by engineered and evolved S. cerevisiae strains depends upon epistatic interactions among genes encoding a xylose reductase (GRE3), a component of MAP Kinase (MAPK) signaling (HOG1), a regulator of Protein Kinase A (PKA) signaling (IRA2), and a scaffolding protein for mitochondrial iron-sulfur (Fe-S) cluster biogenesis (ISU1). Interestingly, the mutation in IRA2 only impacted anaerobic xylose consumption and required the loss of ISU1 function, indicating a previously unknown connection between PKA signaling, Fe-S cluster biogenesis, and anaerobiosis. Proteomic and metabolomic comparisons revealed that the xylose-metabolizing mutant strains exhibit altered metabolic pathways relative to the parental strain when grown in xylose. Further analyses revealed that interacting mutations in HOG1 and ISU1 unexpectedly elevated mitochondrial respiratory proteins and enabled rapid aerobic respiration of xylose and other non-fermentable carbon substrates. Our findings suggest a surprising connection between Fe-S cluster biogenesis and signaling that facilitates aerobic respiration and anaerobic fermentation of xylose, underscoring how much remains unknown about the eukaryotic signaling systems that regulate carbon metabolism.

  13. Antibiofilm activity of carboxymethyl chitosan on the biofilms of non-Candida albicans Candida species.

    Science.gov (United States)

    Tan, Yulong; Leonhard, Matthias; Moser, Doris; Schneider-Stickler, Berit

    2016-09-20

    Although most cases of candidiasis have been attributed to Candida albicans, non-C. albicans Candida species have been isolated in increasing numbers in patients. In this study, we determined the inhibition of carboxymethyl chitosan (CM-chitosan) on single and mixed species biofilm of non-albicans Candida species, including Candida tropicalis, Candida parapsilosis, Candida krusei and Candida glabrata. Biofilm by all tested species in microtiter plates were inhibited nearly 70%. CM-chitosan inhibited mixed species biofilm in microtiter plates and also on medical materials surfaces. To investigate the mechanism, the effect of CM-chitosan on cell viability and biofilm growth was employed. CM-chitosan inhibited Candida planktonic growth as well as adhesion. Further biofilm formation was inhibited with CM-chitosan added at 90min, 12h or 24h after biofilm initiation. CM-chitosan was not only able to inhibit the metabolic activity of Candida cells, but was also active upon the establishment and the development of biofilms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Silver colloidal nanoparticles: effect on matrix composition and structure of Candida albicans and Candida glabrata biofilms.

    Science.gov (United States)

    Monteiro, D R; Silva, S; Negri, M; Gorup, L F; de Camargo, E R; Oliveira, R; Barbosa, D B; Henriques, M

    2013-04-01

    The aim of this study was to assess the effect of different silver nanoparticles (SN) concentrations on the matrix composition and structure of Candida albicans and Candida glabrata biofilms. Candida biofilms were developed in 6-well microtiter plates during 48 h. After, these biofilms were exposed to 13.5 or 54 μg SN ml(-1) for 24 h. Then, extracellular matrices were extracted from biofilms and analysed chemically in terms of proteins, carbohydrates and DNA. To investigate the biofilm structure, scanning electron microscopy (SEM) and epifluorescence microscopy were used. SN interfered with the matrix composition of Candida biofilms tested in terms of protein, carbohydrate and DNA, except for the protein content of C. albicans biofilm. By SEM, Candida biofilms treated with SN revealed structural differences, when compared with the control groups. Further, SN showed a trend of agglomeration within the biofilms. Epifluorescence microscopy images suggest that SN induced damage on cell walls of the Candida isolates tested. In general, irrespective of concentration, SN affected the matrix composition and structure of Candida biofilms and these findings may be related to the mechanisms of biocide action of SN. This study reveals new insights about the behaviour of SN when in contact with Candida biofilms. SN may contribute to the development of therapies to prevent or control Candida infections. © 2012 The Society for Applied Microbiology.

  15. Sugarcane straw as a feedstock for xylitol production by Candida guilliermondii FTI 20037.

    Science.gov (United States)

    Hernández-Pérez, Andrés Felipe; de Arruda, Priscila Vaz; Felipe, Maria das Graças de Almeida

    2016-01-01

    Sugarcane straw has become an available lignocellulosic biomass since the progressive introduction of the non-burning harvest in Brazil. Besides keeping this biomass in the field, it can be used as a feedstock in thermochemical or biochemical conversion processes. This makes feasible its incorporation in a biorefinery, whose economic profitability could be supported by integrated production of low-value biofuels and high-value chemicals, e.g., xylitol, which has important industrial and clinical applications. Herein, biotechnological production of xylitol is presented as a possible route for the valorization of sugarcane straw and its incorporation in a biorefinery. Nutritional supplementation of the sugarcane straw hemicellulosic hydrolyzate as a function of initial oxygen availability was studied in batch fermentation of Candida guilliermondii FTI 20037. The nutritional supplementation conditions evaluated were: no supplementation; supplementation with (NH4)2SO4, and full supplementation with (NH4)2SO4, rice bran extract and CaCl2·2H2O. Experiments were performed at pH 5.5, 30°C, 200rpm, for 48h in 125mL Erlenmeyer flasks containing either 25 or 50mL of medium in order to vary initial oxygen availability. Without supplementation, complete consumption of glucose and partial consumption of xylose were observed. In this condition the maximum xylitol yield (0.67gg(-1)) was obtained under reduced initial oxygen availability. Nutritional supplementation increased xylose consumption and xylitol production by up to 200% and 240%, respectively. The maximum xylitol volumetric productivity (0.34gL(-1)h(-1)) was reached at full supplementation and increased initial oxygen availability. The results demonstrated a combined effect of nutritional supplementation and initial oxygen availability on xylitol production from sugarcane straw hemicellulosic hydrolyzate. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  16. Kinetic behavior of Candida tropicalis during xylitol production using ...

    African Journals Online (AJOL)

    use

    2011-11-21

    Nov 21, 2011 ... yeast extract, 3.0; peptone, 5.0; agar, 20 and xylose, 10.0 in place of glucose (pH ... 10% was taken as the inoculum volume for the ... Rates of cellular growth, xylose uptake, glucose uptake and xylitol ... Cell concentration was determined by means of a calibration curve .... biomass growth or respiration.

  17. Malassezia versus Candida in Healthy Dogs

    Directory of Open Access Journals (Sweden)

    Sihelská Z.

    2017-03-01

    Full Text Available The genera Malassezia and Candida include yeasts which are members of the normal mycobiota of the skin and mucosal sites of humans and other warm-blooded animals. These yeasts are associated with a variety of dermatological disorders and also systemic diseases in humans and other animals. This study confirms the occurrence of Malassezia and Candida species in healthy dogs. Samples were collected from different body sites: external ear canal, interdigital area, skin of the axilla and of the neck, and the oral and rectal mucosae. The isolates were identified using phenotypic methods (biochemical-physiological and morphological characteristics. The presence of yeasts were investigated in the specimens from 70 healthy dogs. Malassezia species were isolated in 44 dogs from which 84 Malassezia isolates were obtained. Only one Candida isolate was obtained from the dogs examined. It was found that Candida does not occur in dogs normally and Malassezia was the main colonizing yeast in healthy dogs.

  18. Candida infection of a prosthetic shoulder joint

    Energy Technology Data Exchange (ETDEWEB)

    Lichtman, E.A.

    1983-09-01

    A heroin addict developed a Candida parapsilosis infection in a prosthetic shoulder joint. Radiographs showed loose fragments of cement with prosthetic loosening. The patient was treated with removal of the prosthesis and intravenous amphotericin B followed by oral ketoconazole.

  19. Development of DNA probes for Candida albicans

    International Nuclear Information System (INIS)

    Cheung, L.L.; Hudson, J.B.

    1988-01-01

    An attempt was made to produce DNA probes that could be used as a rapid and efficient means of detecting candidiasis (invasive Candida infection) in immunocompromised patients. Whole DNA from Candida albicans was digested with restriction endonuclease, and the resulting fragments were randomly cloned into a plasmid vector. Several recombinant plasmids were evaluated for cross-hybridization to various other Candida species, other fungal DNAs, and to nonfungal DNAs. Cross reactions were observed between the probes and different yeasts, but none with unrelated DNAs. Some recombinants were genus-specific, and two of these were applied to the analysis of C. albicans growth curves. It became evident that, although both 32 P- and biotin-labelled probes could be made quite sensitive, a possible limitation in their diagnostic potential was the poor liberation of Candida DNA from cells. Thus, better methods of treatment of clinical specimens will be required before such probes will be useful in routine diagnosis

  20. Candida infection of a prosthetic shoulder joint

    International Nuclear Information System (INIS)

    Lichtman, E.A.; Veterans Administration Medical Center, New York

    1983-01-01

    A heroin addict developed a Candida parapsilosis infection in a prosthetic shoulder joint. Radiographs showed loose fragments of cement with prosthetic loosening. The patient was treated with removal of the prosthesis and intravenous amphotericin B followed by oral ketoconazole. (orig.)

  1. Development of DNA probes for Candida albicans

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, L.L.; Hudson, J.B.

    1988-07-01

    An attempt was made to produce DNA probes that could be used as a rapid and efficient means of detecting candidiasis (invasive Candida infection) in immunocompromised patients. Whole DNA from Candida albicans was digested with restriction endonuclease, and the resulting fragments were randomly cloned into a plasmid vector. Several recombinant plasmids were evaluated for cross-hybridization to various other Candida species, other fungal DNAs, and to nonfungal DNAs. Cross reactions were observed between the probes and different yeasts, but none with unrelated DNAs. Some recombinants were genus-specific, and two of these were applied to the analysis of C. albicans growth curves. It became evident that, although both /sup 32/P- and biotin-labelled probes could be made quite sensitive, a possible limitation in their diagnostic potential was the poor liberation of Candida DNA from cells. Thus, better methods of treatment of clinical specimens will be required before such probes will be useful in routine diagnosis.

  2. In vitro modification of Candida albicans invasiveness.

    Science.gov (United States)

    Fontenla de Petrino, S E; de Jorrat, M E; Sirena, A; Valdez, J C; Mesón, O

    1986-05-01

    Candida albicans produces germ-tubes (GT) when it is incubated in animal or human serum. This dimorphism is responsible for its invasive ability. The purpose of the present paper is (1) to evaluate the ability of rat peritoneal macrophages to inhibit GT production of ingested Candida albicans, obtained from immunized rats and then activated in vitro with Candida-induced lymphokines; (2) to determinate any possible alteration of phagocytic and candidacidal activities. The phagocytes were obtained from rats immunized with viable C. albicans. Some of them were exposed to Candida-induced lymphokines in order to activate the macrophages in vitro. The monolayers of activated, immune and normal macrophages were infected with a C. albicans suspension during 4 hr. Activated macrophages presented not only the highest phagocytic and candidacidal activities but a noticeable inhibition of GT formation and incremented candidacidal activity.

  3. Ecology of Candida-associated Denture Stomatitis

    OpenAIRE

    Budtz-Jørgensen, Ejvind

    2011-01-01

    Introduction of a prosthesis into the oral cavity results in profound alterations of the environmental conditions as the prosthesis and the underlying mucosa become colonized with oral microorganisms, including Candida spp. This may lead to denture stomatitis, a non-specific inflammatory reaction against microbial antigens, toxins and enzymes produced by the colonizing microorganisms. The role of Candida in the etiology of denture stomatitis is indicated by an increased number of yeasts on th...

  4. Candida in saliva of Brazilian hemophilic patients

    OpenAIRE

    Pereira,Claudio Maranhão; Pires,Fábio Ramôa; Corrêa,Maria Elvira Pizzigatti; di Hipólito Júnior,Osvaldo; Almeida,Oslei Paes de

    2004-01-01

    Hemophilia is a common hereditary hemorrhagic disorder, however little is known about the oral microflora of hemophilic patients. The aim of this study was to quantify the Candida and identify its species in non-stimulated saliva of hemophilic patients, and consider its relationship with clinical factors influencing Candida carriage. This study comprised evaluation of 86 hemophilic patients of the Hematology Center/UNICAMP and 43 healthy subjects as controls. All patients were submitted to an...

  5. Mutations in iron-sulfur cluster proteins that improve xylose utilization

    Science.gov (United States)

    Froehlich, Allan; Henningsen, Brooks; Covalla, Sean; Zelle, Rintze M.

    2018-03-20

    There is provided an engineered host cells comprising (a) one or more mutations in one or more endogenous genes encoding a protein associated with iron metabolism; and (b) at least one gene encoding a polypeptide having xylose isomerase activity, and methods of their use thereof.

  6. Optimization studies on acid hydrolysis of oil palm empty fruit bunch fiber for production of xylose.

    Science.gov (United States)

    Rahman, S H A; Choudhury, J P; Ahmad, A L; Kamaruddin, A H

    2007-02-01

    Oil palm empty fruit bunch fiber is a lignocellulosic waste from palm oil mills. It is a potential source of xylose which can be used as a raw material for production of xylitol, a high value product. The increasing interest on use of lignocellulosic waste for bioconversion to fuels and chemicals is justifiable as these materials are low cost, renewable and widespread sources of sugars. The objective of the present study was to determine the effect of H(2)SO(4) concentration, reaction temperature and reaction time for production of xylose. Batch reactions were carried out under various reaction temperature, reaction time and acid concentrations and Response Surface Methodology (RSM) was followed to optimize the hydrolysis process in order to obtain high xylose yield. The optimum reaction temperature, reaction time and acid concentration found were 119 degrees C, 60 min and 2%, respectively. Under these conditions xylose yield and selectivity were found to be 91.27% and 17.97 g/g, respectively.

  7. NADPH-dependent D-aldose reductases and xylose fermentation in Fusarium oxysporum

    DEFF Research Database (Denmark)

    Panagiotou, Gianni; Christakopoulos, P.

    2004-01-01

    Two aldose (xylose) reductases (ARI and ARII) from Fusarium oxysporum were purified and characterized. The native ARI was a monomer with M-r 41000, pI 5.2 and showed a 52-fold preference for NADPH over NADH, while ARII was homodimeric with a subunit of M-r 37000, pI 3.6 and a 60-fold preference...

  8. Xylose fermentation to biofuels (hydrogen and ethanol) by extreme thermophilic (70 C) mixed culture

    DEFF Research Database (Denmark)

    Chenxi, Zhao; Karakashev, Dimitar Borisov; Lu, W.

    2010-01-01

    -xylose corresponding to 55% of the theoretical hydrogen yield based on acetate metabolic pathway. An empirical model was established to reveal the quantitative effect of factors significant for biohydrogen (quadratic model) production and for bioethanol (linear model) production. Changes in hydrogen/ethanol yields...

  9. Furfural synthesis from D-xylose in the presence of sodium chloride : Microwave versus conventional heating

    NARCIS (Netherlands)

    Xiouras, C.; Radacsi, N.; Sturm, G.S.J.; Stefanidis, G.

    2016-01-01

    We investigate the existence of specific/nonthermal microwave effects for the dehydration reaction of xylose to furfural in the presence of NaCl. Such effects are reported for sugars dehydration reactions in several literature reports. To this end, we adopted three approaches that compare

  10. Creation of a synthetic xylose-inducible promoter for Saccharomyces cerevisiae

    Science.gov (United States)

    Saccharomyces cerevisiae is currently used to produce ethanol from glucose, but it cannot utilize five-carbon sugars contained in the hemicellulose component of biomass feedstocks. S. cerevisiae strains engineered for xylose fermentation have been made using constitutive promoters to express the req...

  11. Lactic acid production from xylose by engineered Saccharomyces cerevisiae without PDC or ADH deletion

    Science.gov (United States)

    Production of lactic acid from renewable sugars has received growing attention as lactic acid can be used for making renewable and bio-based plastics. However, most prior studies have focused on production of lactic acid from glucose despite cellulosic hydrolysates contain xylose as well as glucose....

  12. Ethanol fermentation from lignocellulosic hydrolysate by a recombinant xylose- and cellooligosaccharide-assimilating yeast strain

    Energy Technology Data Exchange (ETDEWEB)

    Katahira, Satoshi; Fukuda, Hideki [Kobe Univ. (Japan). Div. of Molecular Science; Mizuike, Atsuko; Kondo, Akihiko [Kobe Univ. (Japan). Dept. of Chemical Science and Engineering

    2006-10-15

    The sulfuric acid hydrolysate of lignocellulosic biomass, such as wood chips, from the forest industry is an important material for fuel bioethanol production. In this study, we constructed a recombinant yeast strain that can ferment xylose and cellooligosaccharides by integrating genes for the intercellular expressions of xylose reductase and xylitol dehydrogenase from Pichia stipitis, and xylulokinase from Saccharomyces cerevisiae and a gene for displaying ss-glucosidase from Aspergillus acleatus on the cell surface. In the fermentation of the sulfuric acid hydrolysate of wood chips, xylose and cellooligosaccharides were completely fermented after 36 h by the recombinant strain, and then about 30 g/l ethanol was produced from 73 g/l total sugar added at the beginning. In this case, the ethanol yield of this recombinant yeast was much higher than that of the control yeast. These results demonstrate that the fermentation of the lignocellulose hydrolysate is performed efficiently by the recombinant Saccharomyces strain with abilities for xylose assimilation and cellooligosaccharide degradation. (orig.)

  13. Dehydration of xylose to furfural over MCM-41-supported niobium-oxide catalysts.

    Science.gov (United States)

    García-Sancho, Cristina; Sádaba, Irantzu; Moreno-Tost, Ramón; Mérida-Robles, Josefa; Santamaría-González, José; López-Granados, Manuel; Maireles-Torres, Pedro

    2013-04-01

    A series of silica-based MCM-41-supported niobium-oxide catalysts are prepared, characterized by using XRD, N2 adsorption-desorption, X-ray photoelectron spectroscopy, Raman spectroscopy, and pyridine adsorption coupled to FTIR spectroscopy, and tested for the dehydration of D-xylose to furfural. Under the operating conditions used all materials are active in the dehydration of xylose to furfural (excluding the MCM-41 silica support). The xylose conversion increases with increasing Nb2 O5 content. At a loading of 16 wt % Nb2 O5 , 74.5 % conversion and a furfural yield of 36.5 % is achieved at 170 °C, after 180 min reaction time. Moreover, xylose conversion and furfural yield increase with the reaction time and temperature, attaining 82.8 and 46.2 %, respectively, at 190 °C and after 100 min reaction time. Notably, the presence of NaCl in the reaction medium further increases the furfural yield (59.9 % at 170 °C after 180 min reaction time). Moreover, catalyst reutilization is demonstrated by performing at least three runs with no loss of catalytic activity and without the requirement for an intermediate regeneration step. No significant niobium leaching is observed, and a relationship between the structure of the catalyst and the activity is proposed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Succinic acid production from xylose mother liquor by recombinant Escherichia coli strain.

    Science.gov (United States)

    Wang, Honghui; Pan, Jiachuan; Wang, Jing; Wang, Nan; Zhang, Jie; Li, Qiang; Wang, Dan; Zhou, Xiaohua

    2014-11-02

    Succinic acid (1,4-butanedioic acid) is identified as one of important building-block chemicals. Xylose mother liquor is an abundant industrial residue in xylitol biorefining industry. In this study, xylose mother liquor was utilized to produce succinic acid by recombinant Escherichia coli strain SD121, and the response surface methodology was used to optimize the fermentation media. The optimal conditions of succinic acid fermentation were as follows: 82.62 g L -1 total initial sugars, 42.27 g L -1 MgCO 3 and 17.84 g L -1 yeast extract. The maximum production of succinic acid was 52.09 ± 0.21 g L -1 after 84 h with a yield of 0.63 ± 0.03 g g -1 total sugar, approaching the predicted value (53.18 g L -1 ). It was 1.78-fold of the production of that obtained with the basic medium. This was the first report on succinic acid production from xylose mother liquor by recombinant E. coli strains with media optimization using response surface methodology. This work suggested that the xylose mother liquor could be an alternative substrate for the economical production of succinic acid by recombinant E. coli strains.

  15. Engineering of Saccharomyces cerevisiae for the production of fuel ethanol from xylose

    NARCIS (Netherlands)

    Kuijper, S.M.

    2006-01-01

    For various reasons mankind is looking for alternatives for fossil fuels. One of these alternatives is ethanol made from plant biomass. However, the plant material when broken down by hydrolysis into its sugar monomers contains a significant amount of xylose, a 5-carbon-sugar or pentose. Contrary to

  16. Biphasic single-reactor process for dehydration of xylose and hydrogenation of produced furfural

    NARCIS (Netherlands)

    Ordomskiy, V.; Schouten, J.C.; Schaaf, van der J.; Nijhuis, T.A.

    2013-01-01

    The processes of xylose dehydration and the consecutive furfural hydrogenation have been combined in a single biphasic reactor. The dehydration was studied over Amberlyst-15 and the hydrogenation over a hydrophobic Ru/C catalyst. 1-Butanol, 2-methyltetrahydrofuran and cyclohexane were used as

  17. Comparative genomics of xylose-fermenting fungi for enhanced biofuel production

    Science.gov (United States)

    Dana J. Wolbach; Alan Kuo; Trey K. Sato; Katlyn M. Potts; Asaf A. Salamov; Kurt M. LaButti; Hui Sun; Alicia Clum; Jasmyn L. Pangilinan; Erika A. Lindquist; Susan Lucas; Alla Lapidus; Mingjie Jin; Christa Gunawan; Venkatesh Balan; Bruce E. Dale; Thomas W. Jeffries; Robert Zinkel; Kerrie W. Barry; Igor V. Grigoriev; Audrey P. Gasch

    2011-01-01

    Cellulosic biomass is an abundant and underused substrate for biofuel production. The inability of many microbes to metabolize the pentose sugars abundant within hemicellulose creates specific challenges for microbial biofuel production from cellulosic material. Although engineered strains of Saccharomyces cerevisiae can use the pentose xylose, the fermentative...

  18. Xylose utilizing zymomonas mobilis with improved ethanol production in biomass hydrolysate medium

    Science.gov (United States)

    Caimi, Perry G; Hitz, William D; Stieglitz, Barry; Viitanen, Paul V

    2013-07-02

    Xylose-utilizing, ethanol producing strains of Zymomonas mobilis with improved performance in medium comprising biomass hydrolysate were isolated using an adaptation process. Independently isolated strains were found to have independent mutations in the same coding region. Mutation in this coding may be engineered to confer the improved phenotype.

  19. PET-CT manifestation of Candida esophagitis

    Energy Technology Data Exchange (ETDEWEB)

    Bahk, Yong Whee [Sung-Ae Hospital, Seoul (Korea, Republic of); O, Joo Hyun [Kangnam St. Mary' s Hospital, Catholic University Medical School, Seoul (Korea, Republic of)

    2007-04-15

    Candida esophagitis (moniliasis) is the most common infection of the gullet and has generally been attributed to as a complication of immune suppressed state. However, as the current case. Holt found the disease to occur in 3 of his 13 patients without predisposing condition. Predisposing factors other than immune deficient conditions include aplastic anemia, alcoholism and Parkinson's disease and age, diabetes mellitus, and disruption of mucosal integrity. Growing prevalence of Candida esophagitis in recent years is accounted for by an increase in the number of patients with organ transplantation, malignancy and AIDS as well as populrization of endoscopy. Microorganisms that reached the esophagus in oral secretions are rarely cultured from the esophageal surface. Of many species C. albicans is the most common offender although C. tropicalis has also been isolated with high prevalence, particularly in the patients with cancer and disseminated candidiasis. Clinically, the patients with Candida esophagitis seek medical care for esophageal or retrosternal pain, dysphagia or distress. Candida esophagitis may be the extension from oropharyngeal infection but in the majority the esophagus is the sole site of infection. The middle and lower thirds of the esophagus are more typically affected than the upper third. Diagnosis can be indicated by double contrast esophagography or endoscopy and confirmed by potassium hydroxide (KOH) stain or biopsy. It is to be noted that the more presence of Candida in smear or cultured specimen cannot indict Candida as definitive offender. Differential diagnosis includes herpes simplex infection, cytomegalovirus infection, reflux esophagitis or radiation esophagitis.

  20. PET-CT manifestation of Candida esophagitis

    International Nuclear Information System (INIS)

    Bahk, Yong Whee; O, Joo Hyun

    2007-01-01

    Candida esophagitis (moniliasis) is the most common infection of the gullet and has generally been attributed to as a complication of immune suppressed state. However, as the current case. Holt found the disease to occur in 3 of his 13 patients without predisposing condition. Predisposing factors other than immune deficient conditions include aplastic anemia, alcoholism and Parkinson's disease and age, diabetes mellitus, and disruption of mucosal integrity. Growing prevalence of Candida esophagitis in recent years is accounted for by an increase in the number of patients with organ transplantation, malignancy and AIDS as well as populrization of endoscopy. Microorganisms that reached the esophagus in oral secretions are rarely cultured from the esophageal surface. Of many species C. albicans is the most common offender although C. tropicalis has also been isolated with high prevalence, particularly in the patients with cancer and disseminated candidiasis. Clinically, the patients with Candida esophagitis seek medical care for esophageal or retrosternal pain, dysphagia or distress. Candida esophagitis may be the extension from oropharyngeal infection but in the majority the esophagus is the sole site of infection. The middle and lower thirds of the esophagus are more typically affected than the upper third. Diagnosis can be indicated by double contrast esophagography or endoscopy and confirmed by potassium hydroxide (KOH) stain or biopsy. It is to be noted that the more presence of Candida in smear or cultured specimen cannot indict Candida as definitive offender. Differential diagnosis includes herpes simplex infection, cytomegalovirus infection, reflux esophagitis or radiation esophagitis

  1. Analytical Validation of a New Enzymatic and Automatable Method for d-Xylose Measurement in Human Urine Samples

    Directory of Open Access Journals (Sweden)

    Israel Sánchez-Moreno

    2017-01-01

    Full Text Available Hypolactasia, or intestinal lactase deficiency, affects more than half of the world population. Currently, xylose quantification in urine after gaxilose oral administration for the noninvasive diagnosis of hypolactasia is performed with the hand-operated nonautomatable phloroglucinol reaction. This work demonstrates that a new enzymatic xylose quantification method, based on the activity of xylose dehydrogenase from Caulobacter crescentus, represents an excellent alternative to the manual phloroglucinol reaction. The new method is automatable and facilitates the use of the gaxilose test for hypolactasia diagnosis in the clinical practice. The analytical validation of the new technique was performed in three different autoanalyzers, using buffer or urine samples spiked with different xylose concentrations. For the comparison between the phloroglucinol and the enzymatic assays, 224 urine samples of patients to whom the gaxilose test had been prescribed were assayed by both methods. A mean bias of −16.08 mg of xylose was observed when comparing the results obtained by both techniques. After adjusting the cut-off of the enzymatic method to 19.18 mg of xylose, the Kappa coefficient was found to be 0.9531, indicating an excellent level of agreement between both analytical procedures. This new assay represents the first automatable enzymatic technique validated for xylose quantification in urine.

  2. Production of xylitol by a Coniochaeta ligniaria strain tolerant of inhibitors and defective in growth on xylose.

    Science.gov (United States)

    Nichols, Nancy N; Saha, Badal C

    2016-05-01

    In conversion of biomass to fuels or chemicals, inhibitory compounds arising from physical-chemical pretreatment of the feedstock can interfere with fermentation of the sugars to product. Fungal strain Coniochaeta ligniaria NRRL30616 metabolizes the furan aldehydes furfural and 5-hydroxymethylfurfural, as well as a number of aromatic and aliphatic acids and aldehydes. Use of NRRL30616 to condition biomass sugars by metabolizing the inhibitors improves their fermentability. Wild-type C. ligniaria has the ability to grow on xylose as sole source of carbon and energy, with no accumulation of xylitol. Mutants of C. ligniaria unable to grow on xylose were constructed. Xylose reductase and xylitol dehydrogenase activities were reduced by approximately two thirds in mutant C8100. The mutant retained ability to metabolize inhibitors in biomass hydrolysates. Although C. ligniaria C8100 did not grow on xylose, the strain converted a portion of xylose to xylitol, producing 0.59 g xylitol/g xylose in rich medium and 0.48 g xylitol/g xylose in corn stover dilute acid hydrolysate. 2016 American Institute of Chemical Engineers Biotechnol. Prog., 2016 © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:606-612, 2016. © 2016 American Institute of Chemical Engineers.

  3. Expression of protein engineered NADP{sup +}-dependent xylitol dehydrogenase increases ethanol production from xylose in recombinant Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Matsushika, Akinori; Inoue, Hiroyuki; Murakami, Katsuji; Takimura, Osamu; Sawayama, Shigeki [National Institute of Advanced Industrial Science and Technology, Hiroshima (Japan). Biomass Technology Research Center; Watanabe, Seiya; Kodaki, Tsutomu; Makino, Keisuke [Kyoto Univ. (Japan). Inst. of Advanced Energy

    2008-11-15

    A recombinant Saccharomyces cerevisiae strain transformed with xylose reductase (XR) and xylitol dehydrogenase (XDH) genes from Pichia stipitis has the ability to convert xylose to ethanol together with the unfavorable excretion of xylitol, which may be due to cofactor imbalance between NADPH-preferring XR and NAD{sup +}-dependent XDH. To reduce xylitol formation, we have already generated several XDH mutants with a reversal of coenzyme specificity toward NADP{sup +}. In this study, we constructed a set of recombinant S. cerevisiae strains with xylose-fermenting ability, including protein-engineered NADP{sup +}-dependent XDH-expressing strains. The most positive effect on xylose-to-ethanol fermentation was found by using a strain named MA-N5, constructed by chromosomal integration of the gene for NADP{sup +}-dependent XDH along with XR and endogenous xylulokinase genes. The MA-N5 strain had an increase in ethanol production and decrease in xylitol excretion compared with the reference strain expressing wild-type XDH when fermenting not only xylose but also mixed sugars containing glucose and xylose. Furthermore, the MA-N5 strain produced ethanol with a high yield of 0.49 g of ethanol/g of total consumed sugars in the nonsulfuric acid hydrolysate of wood chips. The results demonstrate that glucose and xylose present in the lignocellulosic hydrolysate can be efficiently fermented by this redox-engineered strain. (orig.)

  4. Breeding of a xylose-fermenting hybrid strain by mating genetically engineered haploid strains derived from industrial Saccharomyces cerevisiae.

    Science.gov (United States)

    Inoue, Hiroyuki; Hashimoto, Seitaro; Matsushika, Akinori; Watanabe, Seiya; Sawayama, Shigeki

    2014-12-01

    The industrial Saccharomyces cerevisiae IR-2 is a promising host strain to genetically engineer xylose-utilizing yeasts for ethanol fermentation from lignocellulosic hydrolysates. Two IR-2-based haploid strains were selected based upon the rate of xylulose fermentation, and hybrids were obtained by mating recombinant haploid strains harboring heterogeneous xylose dehydrogenase (XDH) (wild-type NAD(+)-dependent XDH or engineered NADP(+)-dependent XDH, ARSdR), xylose reductase (XR) and xylulose kinase (XK) genes. ARSdR in the hybrids selected for growth rates on yeast extract-peptone-dextrose (YPD) agar and YP-xylose agar plates typically had a higher activity than NAD(+)-dependent XDH. Furthermore, the xylose-fermenting performance of the hybrid strain SE12 with the same level of heterogeneous XDH activity was similar to that of a recombinant strain of IR-2 harboring a single set of genes, XR/ARSdR/XK. These results suggest not only that the recombinant haploid strains retain the appropriate genetic background of IR-2 for ethanol production from xylose but also that ARSdR is preferable for xylose fermentation.

  5. Enhanced Furfural Yields from Xylose Dehydration in the gamma-Valerolactone/Water Solvent System at Elevated Temperatures.

    Science.gov (United States)

    Sener, Canan; Motagamwala, Ali Hussain; Alonso, David Martin; Dumesic, James

    2018-05-18

    High yields of furfural (>90%) were achieved from xylose dehydration in a sustainable solvent system composed of -valerolactone (GVL), a biomass derived solvent, and water. It is identified that high reaction temperatures (e.g., 498 K) are required to achieve high furfural yield. Additionally, it is shown that the furfural yield at these temperatures is independent of the initial xylose concentration, and high furfural yield is obtained for industrially relevant xylose concentrations (10 wt%). A reaction kinetics model is developed to describe the experimental data obtained with solvent system composed of 80 wt% GVL and 20 wt% water across the range of reaction conditions studied (473 - 523 K, 1-10 mM acid catalyst, 66 - 660 mM xylose concentration). The kinetic model demonstrates that furfural loss due to bimolecular condensation of xylose and furfural is minimized at elevated temperature, whereas carbon loss due to xylose degradation increases with increasing temperature. Accordingly, the optimal temperature range for xylose dehydration to furfural in the GVL/H2O solvent system is identified to be from 480 to 500 K. Under these reaction conditions, furfural yield of 93% is achieved at 97% xylan conversion from lignocellulosic biomass (maple wood). © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Glucose(xylose isomerase production by Streptomyces sp. CH7 grown on agricultural residues

    Directory of Open Access Journals (Sweden)

    Kankiya Chanitnun

    2012-09-01

    Full Text Available Streptomyces sp. CH7 was found to efficiently produce glucose(xylose isomerase when grown on either xylan or agricultural residues. This strain produced a glucose(xylose isomerase activity of roughly 1.8 U/mg of protein when it was grown in medium containing 1% xylose as a carbon source. Maximal enzymatic activities of about 5 and 3 U/mg were obtained when 1% xylan and 2.5% corn husks were used, respectively. The enzyme was purified from a mycelial extract to 16-fold purity with only two consecutive column chromatography steps using Macro-prep DEAE and Sephacryl-300, respectively. The approximate molecular weight of the purified enzyme is 170 kDa, and it has four identical subunits of 43.6 kDa as estimated by SDS-PAGE. Its Km values for glucose and xylose were found to be 258.96 and 82.77 mM, respectively, and its Vmax values are 32.42 and 63.64 μM/min/mg, respectively. The purified enzyme is optimally active at 85ºC and pH 7.0. It is stable at pH 5.5-8.5 and at temperatures up to 60ºC after 30 min. These findings indicate that glucose(xylose isomerase from Streptomyces sp. CH7 has the potential for industrial applications, especially for high-fructose syrup production and bioethanol fermentation from hemicellulosic hydrolysates by Saccharomyces cerevisiae.

  7. Candida infanticola and Candida spencermartinsiae yeasts: Possible emerging species in cancer patients

    NARCIS (Netherlands)

    Shokohi, T.; Aslani, N.; Ahangarkani, F.; Meyabadi, M.F.; Hagen, F.; Meis, J.F.G.M.; Boekhout, T.; Kolecka, A.; Badali, H.

    2018-01-01

    Opportunistic infections due to Candida species occur frequently in intensive care settings. We investigated the prevalence of Candida species among 65 clinical specimens obtained from 200 cancer patients by phenotypic and molecular (ITS sequencing and AFLP) methods. Among the 65 yeast isolates,

  8. Candida infanticola and Candida spencermartinsiae yeasts: Possible emerging species in cancer patients

    NARCIS (Netherlands)

    Shokohi, T.; Aslani, N.; Ahangarkani, F.; Meyabadi, M.F.; Hagen, F.; Meis, J.F.; Boekhout, T.; Kolecka, A.; Badali, H.

    Opportunistic infections due to Candida species occur frequently especially in intensive care settings. We investigated the prevalence of Candida species among 65 clinical specimens obtained from 200 cancer patients by phenotypic and molecular (ITS sequencing and AFLP) methods. Among the 65 yeast

  9. Candida infanticola and Candida spencermartinsiae yeasts : Possible emerging species in cancer patients

    NARCIS (Netherlands)

    Shokohi, Tahereh; Aslani, Narges; Ahangarkani, Fatemeh; Meyabadi, Masoumeh Fatahi; Hagen, Ferry; Meis, Jacques F.; Boekhout, Teun; Kolecka, Anna; Badali, Hamid

    2017-01-01

    Opportunistic infections due to Candida species occur frequently especially in intensive care settings. We investigated the prevalence of Candida species among 65 clinical specimens obtained from 200 cancer patients by phenotypic and molecular (ITS sequencing and AFLP) methods. Among the 65 yeast

  10. Multilocus sequence typing confirms synonymy but highlights differences between Candida albicans and Candida stellatoidea.

    NARCIS (Netherlands)

    Jacobsen, M.D.; Boekhout, T.; Odds, F.C.

    2008-01-01

    We used multi-locus sequence typing (MLST) to investigate 35 yeast isolates representing the two genome-sequenced strains plus the type strain of Candida albicans, four isolates originally identified as Candida stellatoidea type I and 28 representing type strains of other species now regarded as

  11. Beyond Candida albicans: Mechanisms of immunity to non-albicans Candida species

    Science.gov (United States)

    Whibley, Natasha; Gaffen, Sarah L.

    2015-01-01

    The fungal genus Candida encompasses numerous species that inhabit a variety of hosts, either as commensal microbes and/or pathogens. Candida species are a major cause of fungal infections, yet to date there are no vaccines against Candida or indeed any other fungal pathogen. Our knowledge of immunity to Candida mainly comes from studies on C. albicans, the most frequent species associated with disease. However, non-albicans Candida (NAC) species also cause disease and their prevalence is increasing. Although research into immunity to NAC species is still at an early stage, it is becoming apparent that immunity to C. albicans differs in important ways from non-albicans species, with important implications for treatment, therapy and predicted demographic susceptibility. This review will discuss the current understanding of immunity to NAC species in the context of immunity to C. albicans, and highlight as-yet unanswered questions. PMID:26276374

  12. D-xylose test of resorption as a method to determine radiation side effects in small intestine

    International Nuclear Information System (INIS)

    Koest, S.; Keinert, K.; Glaser, F.H.

    1998-01-01

    Background: The D-xylose test is the most important method to determine a disorder of carbohydrates resorption in proximal small intestine. The application is based on an impaired resorption due to pathological change of small intestine surface, leading to a decreased blood level or decreased excretion in urine. Patients and Method: D-xylose test was applied in 91 patients before, shortly after, 1/2 and 1 year after radiotherapy. All patients received an abdominal radiotherapy. We determined the blood level of D-xylose by a capillary blood sample 1 hour after oral D-xylose administration. Results: A significant decrease of the mean blood level of D-xylose to 1.88 mmol/l was determined after radiotherapy in comparison with 2.17 mmol/l before radiotherapy. Half a year after radiotherapy the mean blood level of D-xylose returned to normal. Regarding a threshold value of D-xylose blood level of 1.70 mmol/l 29 patients (32%) showed a pathologically decreased D-xylose resorption after radiotherapy. Twenty out of the 29 patients already showed a normal resorption half a year after the determination of the resorption disorder, 5 patients after 1 year and 4 patients after 1 1/2 years. There was no correlation between the detection of a disorder of D-xylose resorption and of a loss of body weight. The acute clinical side effects seemed to be more marked in connection with a disorder of D-xylose resorption, but this correlation is not significant. Eleven or 14 of the 29 patients, respectively, with pathologically decreased D-xylose resorption only had complaints of lower or upper gastrointestinal tract, respectively, and 10 patients did not have abdominal complaints at all. Conclusions: The D-xylose test is an important and simple method for determination of radiogen induced carbohydrate malabsorption in proximal small intestine. By means of its radiation side effects on small intestine can also be determined in patients who are otherwise free of complaints. (orig.) [de

  13. Thinking beyond the Common Candida Species: Need for Species-Level Identification of Candida Due to the Emergence of Multidrug-Resistant Candida auris.

    Science.gov (United States)

    Lockhart, Shawn R; Jackson, Brendan R; Vallabhaneni, Snigdha; Ostrosky-Zeichner, Luis; Pappas, Peter G; Chiller, Tom

    2017-12-01

    Candida species are one of the leading causes of nosocomial infections. Because much of the treatment for Candida infections is empirical, some institutions do not identify Candida to species level. With the worldwide emergence of the multidrug-resistant species Candida auris , identification of Candida to species level has new clinical relevance. Species should be identified for invasive candidiasis isolates, and species-level identification can be considered for selected noninvasive isolates to improve detection of C. auris . Copyright © 2017 American Society for Microbiology.

  14. Oral Candida colonization and candidiasis in patients with psoriasis.

    Science.gov (United States)

    Bedair, Ahmad A; Darwazeh, Azmi M G; Al-Aboosi, Mustafa M

    2012-11-01

    The objective of this study was to investigate oral Candida colonization and candidosis in a group of patients with psoriasis and controls. A total of 100 patients with psoriasis and matched controls underwent the concentrated oral rinse test for Candida isolation. Candida species were identified by the VITEK 2 Identification System. Categorical variables were evaluated using the χ(2) test. The median Candida count was compared using the Mann-Whitney U test. Oral candidiasis was diagnosed in 3% of the patients with psoriasis. The Candida count and prevalence were significantly higher in the patients with psoriasis compared with controls (69% vs 44%, P Oral Candida was significantly higher in late-onset (at age ≥30 years) compared with early-onset psoriasis (at age oral Candida colonization and candidiasis. Further studies are needed to clarify the predisposing factor(s) for oral Candida in patients with psoriasis. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Evaluation of Candida Albicans Biofilm Formation on Various Dental ...

    African Journals Online (AJOL)

    2016-06-24

    Jun 24, 2016 ... This study compared the susceptibility of six dental restorative materials to Candida albicans adhesion. ... found for the composite and the compomer samples. ..... Candida colonization on acrylic resins and denture liners:.

  16. Plasticity of Candida albicans Biofilms

    Science.gov (United States)

    Daniels, Karla J.

    2016-01-01

    SUMMARY Candida albicans, the most pervasive fungal pathogen that colonizes humans, forms biofilms that are architecturally complex. They consist of a basal yeast cell polylayer and an upper region of hyphae encapsulated in extracellular matrix. However, biofilms formed in vitro vary as a result of the different conditions employed in models, the methods used to assess biofilm formation, strain differences, and, in a most dramatic fashion, the configuration of the mating type locus (MTL). Therefore, integrating data from different studies can lead to problems of interpretation if such variability is not taken into account. Here we review the conditions and factors that cause biofilm variation, with the goal of engendering awareness that more attention must be paid to the strains employed, the methods used to assess biofilm development, every aspect of the model employed, and the configuration of the MTL locus. We end by posing a set of questions that may be asked in comparing the results of different studies and developing protocols for new ones. This review should engender the notion that not all biofilms are created equal. PMID:27250770

  17. Candida in saliva of Brazilian hemophilic patients.

    Science.gov (United States)

    Pereira, Claudio Maranhão; Pires, Fábio Ramôa; Corrêa, Maria Elvira Pizzigatti; di Hipólito Júnior, Osvaldo; Almeida, Oslei Paes de

    2004-12-01

    Hemophilia is a common hereditary hemorrhagic disorder, however little is known about the oral microflora of hemophilic patients. The aim of this study was to quantify the Candida and identify its species in non-stimulated saliva of hemophilic patients, and consider its relationship with clinical factors influencing Candida carriage. This study comprised evaluation of 86 hemophilic patients of the Hematology Center/UNICAMP and 43 healthy subjects as controls. All patients were submitted to anamnesis, intraoral examination and unstimulated saliva collection. Candida counts and species identification were performed in salivary samples. Candida was present in 64% of the hemophilic patients and in 44% of the healthy controls. C. albicans represented 65% and 68% of the isolated species, in hemophiliacs and control group respectively, and C. tropicalis was the second most common species in both groups. These results indicate that hemophilic patients carry Candida more frequently and in higher counts than healthy controls, independently of oral clinical parameter considered, as viral infections, complete dentures, transfusions of hemoderivatives, and salivary flow.

  18. Prevalence of Candida albicans, Candida dubliniensis and Candida africana in pregnant women suffering from vulvovaginal candidiasis in Argentina.

    Science.gov (United States)

    Mucci, María Josefina; Cuestas, María Luján; Landanburu, María Fernanda; Mujica, María Teresa

    Vulvovaginal candidiasis (VVC) is a vulvovaginitis commonly diagnosed in gynecology care. In recent years, the taxonomy of the most important pathogenic Candida species, such as Candida albicans have undergone significant changes. This study examined the prevalence of C. albicans, Candida africana, and Candida dubliniensis in vaginal specimens from 210 pregnant women suffering from vulvovaginitis or having asymptomatic colonization. Phenotypic and molecular methods were used for the identification of the species. During the studied period, 55 isolates of Candida or other yeasts were obtained from specimens collected from 52 patients suffering from vulvovaginitis (24.8%). C. albicans was the predominant Candida species in 42 isolates (80.7%), either alone or in combination with other species of the genus (5.7%, n=3). Additionally, nine isolates of C. albicans (50%) were obtained from asymptomatic patients (n=18). C. dubliniensis was the causative agent in 2 (3.8%) cases of VVC, and was also isolated in one asymptomatic patient. Molecular assays were carried out using specific PCR to amplify the ACT1-associated intron sequence of C. dubliniensis. The amplification of the HWP1 gene also correctly identified isolates of the species C. albicans and C. dubliniensis. No C. africana was isolated in this work. Some C. albicans isolates were either homozygous or heterozygous at the HWP1 locus. The distribution of heterozygous and homozygous C. albicans isolates at the HWP1 locus was very similar among patients suffering from VVC and asymptomatic patients (p=0.897). The presence of C. albicans and C. dubliniensis, and the absence of C. africana in pregnant is noteworthy. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

  19. A dynamic flux balance model and bottleneck identification of glucose, xylose, xylulose co-fermentation in Saccharomyces cerevisiae

    Science.gov (United States)

    Economically viable production of lignocellulosic ethanol requires efficient conversion of feedstock sugars to ethanol. Saccharomyces cerevisiae cannot ferment xylose, the main five-carbon sugars in biomass, but can ferment xylulose, an enzymatically derived isomer. Xylulose fermentation is slow rel...

  20. Candida costochondritis associated with recent intravenous drug use

    Directory of Open Access Journals (Sweden)

    Simeon J. Crawford

    2016-01-01

    Full Text Available Candida osteoarticular infections are being reported with increasing frequency, possibly due to an expanding population at risk. However, Candida costochondritis is uncommon. We report two cases of Candida costochondritis in patients who presented with subacute-onset chest wall swelling and whose only identifiable risk factor was a history of recent intravenous drug use.

  1. Investigation of Association between Slime Production by Candida ...

    African Journals Online (AJOL)

    Purpose: To determine the susceptibilities of fluconazole and voriconazole based on slime production by Candida spp. Methods: Candida strains (115) isolated in the period between January 2011 and January 2012 were included in this study. ... Yıldırım Beyazıt Training Hospital, were included in this study. Candida ...

  2. The level of glucose-6-phosphate dehydrogenase activity strongly influences xylose fermentation and inhibitor sensitivity in recombinant Saccharomyces cerevisiae strains

    DEFF Research Database (Denmark)

    Jeppsson, M.; Johansson, B.; Jensen, Peter Ruhdal

    2003-01-01

    production levels of G6PDH on xylose fermentation. We used a synthetic promoter library and the copper-regulated CUP1 promoter to generate G6PDH-activities between 0% and 179% of the wildtype level. G6PDH-activities of 1% and 6% of the wild-type level resulted in 2.8- and 5.1-fold increase in specific xylose...

  3. Electrochemistry for the Generation of Renewable Chemicals: One-Pot Electrochemical Deoxygenation of Xylose to δ-Valerolactone.

    Science.gov (United States)

    James, Olusola O; Sauter, Waldemer; Schröder, Uwe

    2017-05-09

    In this study, the electrochemical conversion of xylose to δ-valerolactone via carbonyl intermediates is demonstrated. The conversion was achieved in aqueous media and at ambient conditions. This study also demonstrates that the feedstock for production of renewable chemicals and biofuels through electrochemistry can be extended to primary carbohydrate molecules. This is the first report on a one-pot electrochemical deoxygenation of xylose to δ-valerolactone. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Engineering and two-stage evolution of a lignocellulosic hydrolysate-tolerant Saccharomyces cerevisiae strain for anaerobic fermentation of xylose from AFEX pretreated corn stover.

    Directory of Open Access Journals (Sweden)

    Lucas S Parreiras

    Full Text Available The inability of the yeast Saccharomyces cerevisiae to ferment xylose effectively under anaerobic conditions is a major barrier to economical production of lignocellulosic biofuels. Although genetic approaches have enabled engineering of S. cerevisiae to convert xylose efficiently into ethanol in defined lab medium, few strains are able to ferment xylose from lignocellulosic hydrolysates in the absence of oxygen. This limited xylose conversion is believed to result from small molecules generated during biomass pretreatment and hydrolysis, which induce cellular stress and impair metabolism. Here, we describe the development of a xylose-fermenting S. cerevisiae strain with tolerance to a range of pretreated and hydrolyzed lignocellulose, including Ammonia Fiber Expansion (AFEX-pretreated corn stover hydrolysate (ACSH. We genetically engineered a hydrolysate-resistant yeast strain with bacterial xylose isomerase and then applied two separate stages of aerobic and anaerobic directed evolution. The emergent S. cerevisiae strain rapidly converted xylose from lab medium and ACSH to ethanol under strict anaerobic conditions. Metabolomic, genetic and biochemical analyses suggested that a missense mutation in GRE3, which was acquired during the anaerobic evolution, contributed toward improved xylose conversion by reducing intracellular production of xylitol, an inhibitor of xylose isomerase. These results validate our combinatorial approach, which utilized phenotypic strain selection, rational engineering and directed evolution for the generation of a robust S. cerevisiae strain with the ability to ferment xylose anaerobically from ACSH.

  5. Doğal florada yetişen sarıçiçekli gazal boynuzu (Lotus corniculatus L. ve dar yapraklı gazal boynuzunun (Lotus tenuis Waldst. & Kit. toprak tercihleri, komşu bitkileri ve yem değerleri

    Directory of Open Access Journals (Sweden)

    Ferat Uzun

    2018-02-01

    Full Text Available In this study, soil preferences of wild birdsfoot trefoil (Lotus corniculatus L. and narrowleaf birdsfoot trefoil (L tenuis Waldst. & Kit. species growing in natural flora of the Black Sea Region (Turkey and the plant species which they interact with, as well as their feed values were investigated. Dominant forage species that interact with L. corniculatus and L. tenuis were determined by the visual estimation method at 126 and 86 locations, respectively, and also seed and soil samples from each location were collected. L. corniculatus preferred soils having higher lime (90.9 vs. 66.4 g kg-1, P=0.003, pH (7.41 vs. 7.14, P=0.001 and containing lower organic matter (20.0 vs. 26.8 g kg-1, P=0.001 compared to L. tenuis. L. corniculatus was neighbor to 89 different species (20.2% legume, 22.5% grass and 57.3% others, whereas L. tenuis was neighbor to 61 different species (41.0% legume, 19.7% grass and 39.3% others. The difference between two species in terms of the frequencies of neighbor plant families was significant (2=10.814, P=0.004. Dominant plant species growing in interaction with these Lotus species were Medicago lupulina, Trifolium pratense, Trifolium repens, Cynodon dactylon, Lolium perenne and Plantago lanceolata. Dactylis glomerata was also neighbor with high frequency to L. corniculatus. L. tenuis had high phosphorus, metabolizable energy and relative feed value, and lower acid and neutral detergent fiber contents. As a result, in the artificial pasture establishments or the improvement of natural rangelands, the aforementioned species growing in harmony in natural environment and exhibiting positive interaction with Lotus species studied should be preferred.

  6. Separate and Simultaneous enzymatic hydrolysis and fermentation of wheat hemicellulose with recombinant xylose utilizing Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Olsson, Lisbeth; Sørensen, H. R.; Dam, B. P

    2006-01-01

    Fermentations with three different xylose-utilizing recombinant Saccharomyces cerevisiae strains (F12, CR4, and CB4) were performed using two different wheat hemicellulose substrates, unfermented starch free fibers, and an industrial ethanol fermentation residue, vinasse. With CR4 and F12......, the maximum ethanol concentrations obtained were 4.3 and 4 g/L, respectively, but F12 converted xylose 15% faster than CR4 during the first 24 h. The comparison of separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) with F12 showed that the highest, maximum...... ethanol concentrations were obtained with SSF. In general, the volumetric ethanol productivity was initially, highest in the SHF, but the overall volumetric ethanol productivity ended up being maximal in the SSF, at 0.013 and 0.010 g/Lh, with starch free fibers and vinasse, respectively....

  7. Dehydration of D-xylose to furfural using acid-functionalized MWCNTs catalysts

    Science.gov (United States)

    Termvidchakorn, Chompoopitch; Itthibenchapong, Vorranutch; Songtawee, Siripit; Chamnankid, Busaya; Namuangruk, Supawadee; Faungnawakij, Kajornsak; Charinpanitkul, Tawatchai; Khunchit, Radchadaporn; Hansupaluk, Nanthiya; Sano, Noriaki; Hinode, Hirofumi

    2017-09-01

    Acid-functionalized multi-wall carbon nanotubes (MWCNTs) catalysts were prepared by a wet chemical sonication with various acid solutions, i.e. H2SO4, H3PO4, HNO3, and HCl. Sulfonic groups and carboxyl groups were detected on MWCNTs with H2SO4 treatment (s-MWCNTs), while only carboxyl groups were presented from other acid treatments. The catalytic dehydration of D-xylose into furfural was evaluated using a batch reactor at 170 °C for 3 h under N2 pressure of 15 bar. The highest furfural selectivity was achieved around 57% by s-MWCNTs catalyst, suggesting a positive role of the sulfonic functionalized groups. The effect of Co species was related to their Lewis acid property resulting in the enhancement of xylose conversion with low selectivity to furfural product. Invited talk at 5th Thailand International Nanotechnology Conference (Nano Thailand-2016), 27-29 November 2016, Nakhon Ratchasima, Thailand.

  8. Improvement of ACE inhibitory activity of casein hydrolysate by Maillard reaction with xylose.

    Science.gov (United States)

    Hong, Xu; Meng, Jun; Lu, Rong-Rong

    2015-01-01

    The Maillard reaction is widely used to improve the functional properties or biological activities of food. The purpose of this study was to investigate the effect of the Maillard reaction on angiotensin I converting enzyme (ACE) inhibitory activity in a casein hydrolysate-xylose system. Two-step hydrolysis was used to prepare casein ACE inhibitory peptides. Maillard reaction products (MRPs) were prepared by heating hydrolyzed casein with xylose at pH 8.0, 110 °C for up to 16 h. The results showed that the content of free amino group decreased (P Maillard reaction (P reaction in the MRPs. The study shows that the Maillard reaction under appropriate conditions can improve the ACE inhibitory activity of casein hydrolysate effectively. © 2014 Society of Chemical Industry.

  9. Effect of Furfural, Vanillin and Syringaldehyde on Candida guilliermondii Growth and Xylitol Biosynthesis

    Science.gov (United States)

    Kelly, Christine; Jones, Opal; Barnhart, Christopher; Lajoie, Curtis

    Xylitol is a five-carbon sugar alcohol with established commercial use as an alternative sweetener and can be produced from hemicellulose hydrolysate. However, there are difficulties with microbiological growth and xylitol biosynthesis on hydrolysate because of the inhibitors formed from hydrolysis of hemicellulose. This research focused on the effect of furfural, vanillin, and syringaldehyde on growth of Candida guilliermondii and xylitol accumulation from xylose in a semi-synthetic medium in microwell plate and bioreactor cultivations. All three compounds reduced specific growth rate, increased lag time, and reduced xylitol production rate. In general, increasing concentration of inhibitor increased the severity of inhibition, except in the case of 0.5 g vanillin per liter, which resulted in a faster late batch phase growth rate and increased biomass yield. At concentrations of 1 g/1 or higher, furfural was the least inhibitory to growth, followed by syringaldehyde. Vanillin most severely reduced specific growth rate. All three inhibitors reduced xylitol production rate approximately to the same degree.

  10. Efficient non-sterilized fermentation of biomass-derived xylose to lactic acid by a thermotolerant Bacillus coagulans NL01.

    Science.gov (United States)

    Ouyang, Jia; Cai, Cong; Chen, Hai; Jiang, Ting; Zheng, Zhaojuan

    2012-12-01

    Xylose is the major pentose and the second most abundant sugar in lignocellulosic feedstock. Its efficient utilization is regarded as a technical barrier to the commercial production of bulk chemicals from lignocellulosic biomass. This work aimed at evaluating the lactic acid production from the biomass-derived xylose using non-sterilized fermentation by Bacillus coagulans NL01. A maximum lactic acid concentration of about 75 g/L was achieved from xylose of 100 g/L after 72 h batch fermentation. Acetic acid and levulinic acid were identified as important inhibitors in xylose fermentation, which markedly reduced lactic acid productivity at 15 and 1.0 g/L, respectively. But low concentrations of formic acid (coagulans NL01, the same preference for glucose, xylose, and arabinose was observed and18.2 g/L lactic acid was obtained after 48 h fermentation. These results proved that B. coagulans NL01 was potentially well-suited for producing lactic acid from underutilized xylose-rich prehydrolysates.

  11. Conversion of hemicelluloses and D-xylose into ethanol by the use of thermophilic anaerobic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-05-01

    Ethanol is a CO{sub 2} neutral liquid fuel that can substitute the use of fossil fuels in the transportation sector, thereby reducing the CO{sub 2} emission to the atmosphere. CO{sub 2} emission is suspected to contribute significantly to the so-called greenhouse effect, the global heating. Substrates for production of ethanol must be cheap and plentiful. This can be met by the use of lignocellulosic biomass such as willow, wheat straw, hardwood and softwood. However, the complexity of these polymeric substrates and the presence of several types of carbohydrates (glucose, xylose, mannose, galactose, arabinose) require additional treatment to release the useful carbohydrates and ferment the major carbohydrates fractions. The costs related to the ethanol-production must be kept at a minimum to be price competitive compared to gasoline. Therefore all of the carbohydrates present in lignocellulose need to be converted into ethanol. Glucose can be fermented to ethanol by yeast strains such as Saccharomyces cerevisiae, which, however, is unable to ferment the other major carbohydrate fraction, D-xylose. Thermophilic anaerobic ethanol producing bacteria can be used for fermentation of the hemicelluloses fraction of lignocellulosic biomass. However, physiological studies of thermophilic anaerobic bacteria have shown that the ethanol yield decreases at increasing substrate concentration. The biochemical limitations causing this phenomenon are not known in detail. Physiological and biochemical studies of a newly characterized thermophilic anaerobic ethanol producing bacterium, Thermoanaerobacter mathranii, was performed. This study included extraction of intracellular metabolites and enzymes of the pentose phosphate pathway and glycolysis. These studies revealed several bottlenecks in the D-xylose metabolism. This knowledge makes way for physiological and genetic engineering of this strain to improve the ethanol yield and productivity at high concentration of D-xylose. (au)

  12. Genome sequence of carboxylesterase, carboxylase and xylose isomerase producing alkaliphilic haloarchaeon Haloterrigena turkmenica WANU15

    Directory of Open Access Journals (Sweden)

    Samy Selim

    2016-03-01

    Full Text Available We report draft genome sequence of Haloterrigena turkmenica strain WANU15, isolated from Soda Lake. The draft genome size is 2,950,899 bp with a G + C content of 64% and contains 49 RNA sequence. The genome sequence can be accessed at DDBJ/EMBL/GenBank under the accession no. LKCV00000000. Keywords: Soda Lake, Haloterrigena turkmenica, Carboxylesterase, Carboxylase, Xylose isomerase, Whole genome sequencing

  13. Identification and characterization of D-xylulokinase from the D-xylose-fermenting fungus, Mucor circinelloides.

    Science.gov (United States)

    Komeda, Hidenobu; Yamasaki-Yashiki, Shino; Hoshino, Kazuhiro; Asano, Yasuhisa

    2014-11-01

    D-Xylulokinase catalyzes the phosphorylation of D-xylulose in the final step of the pentose catabolic pathway to form d-xylulose-5-phosphate. The D-xylulokinase activity was found to be induced by both D-xylose and L-arabinose, as well as some of the other enzymes involved in the pentose catabolism, in the D-xylose-fermenting zygomycetous fungus, Mucor circinelloides NBRC 4572. The putative gene, xyl3, which may encode D-xylulokinase, was detected in the genome sequence of this strain. The amino acid sequence deduced from the gene was more similar to D-xylulokinases from an animal origin than from other fungi. The recombinant enzyme was purified from the E. coli transformant expressing xyl3 and then characterized. The ATP-dependent phosphorylative activity of the enzyme was the highest toward D-xylulose. Its kinetic parameters were determined as Km (D-xylulose) = 0.29 mM and Km (ATP) = 0.51 mM, indicating that the xyl3 gene encoded D-xylulokinase (McXK). Western blot analysis revealed that McXK was induced by L-arabinose as well as D-xylose and the induction was repressed in the presence of D-glucose, suggesting that the enzyme may be involved in the catabolism of D-xylose and L-arabinose and is subject to carbon catabolite repression in this fungus. This is the first study on D-xylulokinase from zygomycetous fungi. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  14. Ethanol production from cellulose, lactose and xylose using yeasts and enzymes. Gewinnung von Ethanol aus Cellulose, Lactose, und Xylose mit Hilfe von Hefen und Enzymen

    Energy Technology Data Exchange (ETDEWEB)

    Schwank, U

    1986-07-03

    Experiments with mixtures of whey and corn showed that more than 85% of the lactose was degraded into ethanol. The applicability of cellulose was investigated by means of potatoes. Cellulase is inhibited by glucose, which is a fermentation intermediate, as well as by the end product ethanol. A cellulase inhibitor in potatoes was detected and stabilized; this inhibitor could be degraded into neutral components by a suitable enzyme. Saccharification and fermentation experiments showed that the cellulose fraction of potatoes can be reduced efficiently. The effects of non-enzymatic pretreatment on enzymatic degradation of cellulose, combined with fermentation of the degradation products, are illustrated by the example of cellulose treated with acid and alkaline substances. A continuous fermentation system was developed from which the ethanol is withdrawn in vapour form. The system made better use of the cellulase activity and increased the efficiency of a xylose-fermenting yeast. The new method is compared with batch experiments in order to assess its efficiency. The advantages of the continuous process are proved for two yeasts of the species Pachysolu and Pichia. Specific fermentation rates up to 0.08 g/(g x h) and fermentation yields up to 0.42 g ethanol/g xylose were achieved with Pichia stipitis.

  15. Iterative optimization of xylose catabolism in Saccharomyces cerevisiae using combinatorial expression tuning.

    Science.gov (United States)

    Latimer, Luke N; Dueber, John E

    2017-06-01

    A common challenge in metabolic engineering is rapidly identifying rate-controlling enzymes in heterologous pathways for subsequent production improvement. We demonstrate a workflow to address this challenge and apply it to improving xylose utilization in Saccharomyces cerevisiae. For eight reactions required for conversion of xylose to ethanol, we screened enzymes for functional expression in S. cerevisiae, followed by a combinatorial expression analysis to achieve pathway flux balancing and identification of limiting enzymatic activities. In the next round of strain engineering, we increased the copy number of these limiting enzymes and again tested the eight-enzyme combinatorial expression library in this new background. This workflow yielded a strain that has a ∼70% increase in biomass yield and ∼240% increase in xylose utilization. Finally, we chromosomally integrated the expression library. This library enriched for strains with multiple integrations of the pathway, which likely were the result of tandem integrations mediated by promoter homology. Biotechnol. Bioeng. 2017;114: 1301-1309. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  16. Xylose-rich polysaccharides from the primary walls of embryogenic cell line of Pinus caribaea.

    Science.gov (United States)

    Mollard, A; Domon, J M; David, H; Joseleau, J P

    1997-08-01

    Embryogenic cell lines of Pinus caribaea were isolated from somatic embryogenesis from zygotic embryos. Previous studies showed that the proteins and glycoproteins were characteristic of the embryogenic state. In the present work we were seeking typical feature in the polysaccharide from the cell walls of embryogenic calli at nine days of culture. Sequential extraction with water, ammonium oxalate, dimethyl sulfoxide, sodium borohydride and 4.3 M potassium hydroxide revealed that the extracted polysaccharides contained high proportions of arabinose and significant amounts of xylose. Fractionation of the hydrosoluble polymers on DEAE cellulose afforded a xylose-rich fraction (80% xylose, 24% glucose and lower properties of fucose and mannose). Methylation analysis and 13C-NMR spectra showed that the glycan backbone consisted of beta 1 --> 4 linked xylosyl residues Similar study of the fractions extracted respectively with DMSO and 4.3 M KOH showed the presence of polydisperse glycoxylans but excluded the presence of xyloglucan in significant amount. This could be a characteristic feature of embryogenic cells walls of Pinus caribaea or could be typical of cells grown as calluses. In the various fractions obtained from DEAE cellulose chromatography of the alkaline extract the infrequent occurrence of fucoxylans beside an arabinogalactan showed again the unusual nature of the cell wall polymers of this embryogenic lines, which seems to differ greatly from those found in the primary wall of cells from suspension cultures.

  17. Acid-catalysed xylose dehydration into furfural in the presence of kraft lignin.

    Science.gov (United States)

    Lamminpää, Kaisa; Ahola, Juha; Tanskanen, Juha

    2015-02-01

    In this study, the effects of kraft lignin (Indulin AT) on acid-catalysed xylose dehydration into furfural were studied in formic and sulphuric acids. The study was done using D-optimal design. Three variables in both acids were included in the design: time (20-80 min), temperature (160-180°C) and initial lignin concentration (0-20 g/l). The dependent variables were xylose conversion, furfural yield, furfural selectivity and pH change. The results showed that the xylose conversion and furfural yield decreased in sulphuric acid, while in formic acid the changes were minor. Additionally, it was showed that lignin has an acid-neutralising capacity, and the added lignin increased the pH of reactant solutions in both acids. The pH rise was considerably lower in formic acid than in sulphuric acid. However, the higher pH did not explain all the changes in conversion and yield, and thus lignin evidently inhibits the formation of furfural. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Efficient Hydrolysis of Rice Straw into Xylose and Glucose by a Two-step Process

    Directory of Open Access Journals (Sweden)

    YAN Lu-lu

    2016-07-01

    Full Text Available The hydrolysis of rice straw into xylose and glucose in dilute sulfuric acid aqueous solution was studied with a two-step process in batch autoclave reactor. The results showed that compared with the traditional one-step acid hydrolysis, both xylose and glucose could be produced in high yields from rice straw by using the two-step acid hydrolysis process. The effects of reaction temperature, reaction time, the amount of rice straw and acid concentration on the hydrolysis of rice straw were systematically studied, and showed that except initial rice straw loading amount, the other parameters had remarkable influence on the products distribution and yields. In the first-step of the hydrolysis process, a high xylose yield of 162.6 g·kg-1 was obtained at 140℃ after 120 min reaction time. When the solid residues from the first step were subjected to a second-step hydrolysis, a glucose yield as high as 216.5 g·kg-1 could be achieved at 180℃ after 120 min. This work provides a promising strategy for the efficient and value-added utilization of agricultural wastes such as rice straw.

  19. Breeding and fermentation characterization of Pachysolen Tannophilus mutant with high ethanol productivity from xylose

    International Nuclear Information System (INIS)

    Pan Lijun; Chu Kaiqing; Yang Peizhou

    2011-01-01

    Currently, few strains can utilize xylose to produce ethanol with very low productivity. By the method of mutation breeding to these strains the rate of lignocellulosic utilization could be improved. In this study, the initial Pachysolen tannophilus As 2.1585 was treated by N + ions implantation of 15 keV. The survival curve showed a saddle model. Considering the survival rate and range of positive mutation, the N + ions implantation of 12.5 × 10 14 ions/cm for mutation breeding of Pachysolen tannophilus was selected. A Pachysolen tannophilus mutant mut-54, which had perfect genetic stability of producing ethanol was screened out after continuous 7 passages. The mut-54 had a higher xylose consumption rate, biomass accumulation and ability of ethanol-resistant than the parent strain. Compared with the parent strain, the ethanol concentration fermented by the mut-54 for 72 h increased by 12.74%, which was more suitable for producing ethanol from xylose than the parent strain. (authors)

  20. Enhanced L-lactic acid production from biomass-derived xylose by a mutant Bacillus coagulans.

    Science.gov (United States)

    Zheng, Zhaojuan; Cai, Cong; Jiang, Ting; Zhao, Mingyue; Ouyang, Jia

    2014-08-01

    Xylose effective utilization is crucial for production of bulk chemicals from low-cost lignocellulosic substrates. In this study, an efficient L-lactate production process from xylose by a mutant Bacillus coagulans NL-CC-17 was demonstrated. The nutritional requirements for L-lactate production by B. coagulans NL-CC-17 were optimized statistically in shake flask fermentations. Corn steep liquor powder and yeast exact were identified as the most significant factors by the two-level Plackett-Burman design. Steepest ascent experiments were applied to approach the optimal region of the two factors, and a central composite design was employed to determine their optimal levels. The optimal medium was used to perform batch fermentation in a 3-l bioreactor. A maximum of 90.29 g l(-1)  L-lactic acid was obtained from 100 g l(-1) xylose in 120 h. When using corn stove prehydrolysates as substrates, 23.49 g l(-1)  L-lactic acid was obtained in 36 h and the yield was 83.09 %.

  1. Low acid hydrothermal fractionation of Giant Miscanthus for production of xylose-rich hydrolysate and furfural.

    Science.gov (United States)

    Kim, Tae Hyun; Ryu, Hyun Jin; Oh, Kyeong Keun

    2016-10-01

    Low acid hydrothermal (LAH) fractionation was developed for the effective recovery of hemicellulosic sugar (mainly xylose) from Miscanthus sacchariflorus Goedae-Uksae 1 (M. GU-1). The xylose yield was maximized at 74.75% when the M. GU-1 was fractionated at 180°C and 0.3wt.% of sulfuric acid for 10min. At this condition, the hemicellulose (mainly xylan) degradation was 86.41%. The difference between xylan degradation and xylose recovery yield, i.e., xylan loss, was 11.66%, as indicated by the formation of decomposed products. The furfural, the value added biochemical product, was also obtained by 0.42g/L at this condition, which was 53.82% of furfural production yield based on the xylan loss. After then, the furfural production continued to increase to a maximum concentration of 1.87g/L, at which point the xylan loss corresponded to 25.87%. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Bioprospecting and evolving alternative xylose and arabinose pathway enzymes for use in Saccharomyces cerevisiae.

    Science.gov (United States)

    Lee, Sun-Mi; Jellison, Taylor; Alper, Hal S

    2016-03-01

    Bioprospecting is an effective way to find novel enzymes from strains with desirable phenotypes. Such bioprospecting has enabled organisms such as Saccharomyces cerevisiae to utilize nonnative pentose sugars. Yet, the efficiency of this pentose catabolism (especially for the case of arabinose) remains suboptimal. Thus, further pathway optimization or identification of novel, optimal pathways is needed. Previously, we identified a novel set of xylan catabolic pathway enzymes from a superior pentose-utilizing strain of Ustilago bevomyces. These enzymes were used to successfully engineer a xylan-utilizing S. cerevisiae through a blended approach of bioprospecting and evolutionary engineering. Here, we expanded this approach to xylose and arabinose catabolic pathway engineering and demonstrated that bioprospected xylose and arabinose catabolic pathways from U. bevomyces offer alternative choices for enabling efficient pentose catabolism in S. cerevisiae. By introducing a novel set of xylose catabolic genes from U. bevomyces, growth rates were improved up to 85 % over a set of traditional Scheffersomyces stipitis pathway genes. In addition, we suggested an alternative arabinose catabolic pathway which, after directed evolution and pathway engineering, enabled S. cerevisiae to grow on arabinose as a sole carbon source in minimal medium with growth rates upwards of 0.05 h(-1). This pathway represents the most efficient growth of yeast on pure arabinose minimal medium. These pathways provide great starting points for further strain development and demonstrate the utility of bioprospecting from U. bevomyces.

  3. Candida transmission and sexual behaviors as risks for a repeat episode of Candida vulvovaginitis.

    Science.gov (United States)

    Reed, Barbara D; Zazove, Philip; Pierson, Carl L; Gorenflo, Daniel W; Horrocks, Julie

    2003-12-01

    To assess associations between female and male factors and the risk of recurring Candida vulvovaginitis. A prospective cohort study of 148 women with Candida vulvovaginitis and 78 of their male sexual partners was conducted at two primary care practices in the Ann Arbor, Michigan, area. Thirty-three of 148 women developed at least one further episode of Candida albicans vulvovaginitis within 1 year of follow-up. Cultures of Candida species from various sites of the woman (tongue, feces, vulva, and vagina) and from her partner (tongue, feces, urine, and semen) did not predict recurrences. Female factors associated with recurrence included recent masturbating with saliva (hazard ratio 2.66 [95% CI 1.17-6.06]) or cunnilingus (hazard ratio 2.94 [95% CI 1.12-7.68]) and ingestion of two or more servings of bread per day (p vulvovaginitis.

  4. Frequency of Candida albicans in Patients with Funguria.

    Science.gov (United States)

    Jamil, Sana; Jamil, Naz; Saad, Uzma; Hafiz, Saleem; Siddiqui, Sualleha

    2016-02-01

    To determine the frequency of Candida albicansin patients with funguria. Descriptive cross-sectional study. Department of Microbiology, Sindh Institute of Urology and Transplantation, from July to December 2012. Patients’ urine samples with fungus/Candida were included. Candida albicans was identified by the production of tubular structures (germ tubes) on microscopy as per standard procedure followed by inoculation on Chrom agar (Oxoid) and Corn Meal-Tween 80 agar (Oxoid). The identification of other non-albicans Candidaspecies was also done both microscopically and macroscopically as per standard procedure. Out of the 289 isolates, 204 (70.6%) were male patients and 85 (29.4%) were female patients, with 165 (57.1%) from the out-patients and 124 (42.9%) from the in-patients. Five species of Candidawere found to be prevalent including 87 (30.1%) Candida albicans, 176 (60.9%) Candida tropicalis, 14 (4.8%) Candida parapsilosis, 8 (2.8%) Candida glabrata and 4 (1.4%) Candida lusitaniae. Majority of patients with funguria were aged above 50 years (60.2%). In the present study, 30.1% patients with funguria had Candida albicans. The most frequently isolated species was Candida tropicalis(60.9%), followed by other non-albicansCandida. This study has shown the emergence of non-albicans Candidaas a major cause of candiduria.

  5. Susceptibility characterisation of Candida spp. to four essential oils

    Directory of Open Access Journals (Sweden)

    C C Rath

    2015-01-01

    Full Text Available In the present investigation, anti-Candida activity of four essential oils i.e. Black cumin (Nigella sativa, Curry leaf (Murraya koienigii, Ajwain (Trachiyspirum ammi, and Betel leaf (Piper betel were screened against four human pathogenic species of Candida viz. Candida albicans, Candida tropicalis, Candida glabrata, and Candida parapsilosis. The minimum inhibitory concentration (MIC values of the oils ranged between 15.62 and 250 μl/ml while studied through tube dilution method. The oils retained their anti-Candida activities even after heat treatment (at 45ΊC, 60ΊC, 100ΊC for 1 hour and also on autoclaving. Both Ajwain and Black Cumin leaf oils showed better anti-Candida activity against Candida albicans, resulting in an irreversible damage to the cells. The anti-Candida activity of these essential oils could be attributable to the membrane inhibition mechanism. The activity of the oils is reported to be microbicidal (Candida-cidal.

  6. Analysis of metabolisms and transports of xylitol using xylose- and xylitol-assimilating Saccharomyces cerevisiae.

    Science.gov (United States)

    Tani, Tatsunori; Taguchi, Hisataka; Akamatsu, Takashi

    2017-05-01

    To clarify the relationship between NAD(P) + /NAD(P)H redox balances and the metabolisms of xylose or xylitol as carbon sources, we analyzed aerobic and anaerobic batch cultures of recombinant Saccharomyces cerevisiae in a complex medium containing 20 g/L xylose or 20 g/L xylitol at pH 5.0 and 30°C. The TDH3p-GAL2 or gal80Δ strain completely consumed the xylose within 24 h and aerobically consumed 92-100% of the xylitol within 96 h, but anaerobically consumed only 20% of the xylitol within 96 h. Cells of both strains grew well in aerobic culture. The addition of acetaldehyde (an effective oxidizer of NADH) increased the xylitol consumption by the anaerobically cultured strain. These results indicate that in anaerobic culture, NAD + generated in the NAD(P)H-dependent xylose reductase reaction was likely needed in the NAD + -dependent xylitol dehydrogenase reaction, whereas in aerobic culture, the NAD + generated by oxidation of NADH in the mitochondria is required in the xylitol dehydrogenase reaction. The role of Gal2 and Fps1 in importing xylitol into the cytosol and exporting it from the cells was analyzed by examining the xylitol consumption in aerobic culture and the export of xylitol metabolized from xylose in anaerobic culture, respectively. The xylitol consumptions of gal80Δ gal2Δ and gal80Δ gal2Δ fps1Δ strains were reduced by 81% and 88% respectively, relative to the gal80Δ strain. The maximum xylitol concentration accumulated by the gal80Δ, gal80Δ gal2Δ, and gal80Δ gal2Δ fps1Δ strains was 7.25 g/L, 5.30 g/L, and 4.27 g/L respectively, indicating that Gal2 and Fps1 transport xylitol both inward and outward. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  7. An innovative biocatalyst for production of ethanol from xylose in a continuous bioreactor.

    Science.gov (United States)

    Silva, C R; Zangirolami, T C; Rodrigues, J P; Matugi, K; Giordano, R C; Giordano, R L C

    2012-01-05

    The use of the hemicellulose fraction of biomass may be important for the feasibility of the production of second generation bioethanol. Wild strains of Saccharomyces cerevisiae are widely used in industry for production of 1st generation ethanol, and the robustness of this yeast is an important advantage in large scale applications. Isomerization of xylose to xylulose is an essential step in this process. This reaction is catalyzed by glucose isomerase (GI). A new biocatalyst is presented here for the simultaneous isomerization and fermentation (SIF) of xylose. GI from Streptomyces rubiginosus was immobilized in chitosan, through crosslinking with glutaraldehyde, and the support containing the immobilized GI (IGI-Ch) was co-immobilized with S. cerevisiae, in calcium alginate gel. The immobilization experiments led to high immobilized protein loads (30-68 mg × g(support)(-1)), high yields (circa of 100%) and high recovered enzyme activity (>90%). The IGI-Ch derivative with maximum activity presented 1700 IU × g(catalyst)(-1), almost twice the activity of a commercial immobilized GI, GENSWEET(®) IGI-HF. At typical operational conditions for xylose SIF operation (pH 5, 30-35 °C, presence of nutrients and ethanol concentrations in the medium up to 70 L(-1)), both derivatives, IGI-Ch and GENSWEET(®) IGI-HF retained app. 90% of the initial activity after 120 h, while soluble GI was almost completely inactive at pH 5, 30 °C. The isomerization xylose/xylulose, catalyzed by IGI-Ch, reached the equilibrium in batch experiments after 4h, with 12,000 IU × L(-1) (7 g(der) × L(-1)), at pH 5 and 30 °C, in the presence of fermentation nutrients. After co-immobilization of IGI-Ch with yeast in alginate gel, this biocatalyst succeeded in producing 12 g × L(-1) of ethanol, 9.5 g × L(-1) of xylitol, 2.5 g × L(-1) of glycerol and 1.9 g × L(-1) of acetate after consumption of 50 g × L(-1) of xylose, in 48 h, using 32.5 × 10(3) IU × L(-1) and 20 g(yeast) × L(-1), at 35

  8. Decreased Killing Activity of Micafungin Against Candida guilliermondii, Candida lusitaniae, and Candida kefyr in the Presence of Human Serum.

    Science.gov (United States)

    Saleh, Qasem; Kovács, Renátó; Kardos, Gábor; Gesztelyi, Rudolf; Kardos, Tamás; Bozó, Aliz; Majoros, László

    2017-09-01

    Currently, echinocandins are first-line drugs for treatment of invasive candidiasis. However, data on how serum influences killing activity of echinocandins against uncommon Candida species are limited. Therefore, the killing activity of micafungin in RPMI-1640 and in 50% serum was compared against Candida guilliermondii, Candida lusitaniae, and Candida kefyr. Minimum inhibitory concentration (MIC) ranges in RPMI-1640 were 0.5-1, 0.12-0.25, and 0.06-0.12 mg/L, respectively. In 50% serum, MICs increased 32- to 256-fold. In RPMI-1640 ≥ 0.25, ≥4, and 32 mg/L micafungin was fungicidal against all four C. kefyr (≤4.04 hours), two of three C. lusitaniae (≤16.10 hours), and two of three C. guilliermondii (≤12.30 hours), respectively. In 50% serum, all three species grew at ≤4 mg/L. Micafungin at 16-32 mg/L was fungicidal against all C. kefyr isolates (≤3.03 hours) and at 32 mg/L was fungistatic against one of three C. lusitaniae isolates. Two C. lusitaniae isolates and all three C. guilliermondii grew at all tested concentrations. Adding human serum to susceptibility test media drew attention to loss of fungicidal or fungistatic activity of micafungin in the presence of serum proteins, which is not predicted by MICs in case of C. kefyr and C. lusitaniae in RPMI-1640. Our results strongly suggest that micafungin and probably other echinocandins should be used with caution against rare Candida species.

  9. Frequency of Candida albicans in Patients with Funguria

    International Nuclear Information System (INIS)

    Jamil, S.; Jamil, N.; Hafiz, S.; Siddiqui, S.; Saad, U.

    2016-01-01

    Objective: To determine the frequency of Candida albicans in patients with funguria. Study Design: Descriptive cross-sectional study. Place and Duration of Study: Department of Microbiology, Sindh Institute of Urology and Transplantation, from July to December 2012. Methodology: Patients urine samples with fungus/Candida were included. Candida albicans was identified by the production of tubular structures (germ tubes) on microscopy as per standard procedure followed by inoculation on Chrom agar (Oxoid) and Corn Meal-Tween 80 agar (Oxoid). The identification of other non-albicans Candida species was also done both microscopically and macroscopically as per standard procedure. Results: Out of the 289 isolates, 204 (70.6 percentage) were male patients and 85 (29.4 percentage) were female patients, with 165 (57.1 percentage) from the out-patients and 124 (42.9 percentage) from the in-patients. Five species of Candida were found to be prevalent including 87 (30.1 percentage) Candida albicans, 176 (60.9 percentage) Candida tropicalis, 14 (4.8 percentage) Candida parapsilosis, 8 (2.8 percentage) Candida glabrata and 4 (1.4 percentage) Candida lusitaniae. Majority of patients with funguria were aged above 50 years (60.2 percentage). Conclusion: In the present study, 30.1 percentage patients with funguria had Candida albicans. The most frequently isolated species was Candida tropicalis (60.9 percentage), followed by other non-albicans Candida. This study has shown the emergence of non-albicans Candida as a major cause of candiduria. (author)

  10. Conversion of hemicellulose and D-xylose into ethanol by the use of thermophilic anaerobic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Sommer, Peter

    1998-02-01

    Ethanol is a CO{sub 2} neutral liquid fuel that can substitute the use of fossil fuels in the transportation sector, thereby reducing the CO{sub 2} emission to the atmoshpere. CO{sub 2} emission is suspected to contribute significantly to the so-called greenhouse effect, the global heating. Substrates for production of ethanol must be cheap and plentiful. This can be met by the use of lignocellulosic biomass such as willow, wheat straw, hardwood and softwood. However, the complexity of these polymeric substrates and the presence of several types of carbohydrates (glucose, xylose, mannose, galactose, arabinose) require additional treatment to release the useful carbohydrates and ferment the major carbohydrates fractions. The costs related to the ethanol-production must be kept at a minimum to be price competitive compared to gasoline. Therefore all of the carbohydrates present in lignocellulose need to be converted into ethanol. Glucose can be fermented to ethanol by yeast strains such as Saccharomyces cerevisiae, which, however, is unable to ferment the other major carbohydrate fraction, D-xylose. The need for a microorganism able to ferment D-xylose is therefore apparent. Thermophilic anaerobic ethanol producing bacteria can therefore be considered for fermentation of D-xylose. Screening of 130 thermophilic anaerobic bacterial strains, from hot-springs, mesophilic and thermophilic biogas plants, paper pulp industries and brewery waste, were examined for production of ethanol from D-xylose and wet-oxidized hemicellulose hydrolysate. Several strains were isolated and one particular strain was selected for best performance during the screening test. This strain was characterized as a new species, Thermoanaerobacter mathranii. However, the ethanol yield on wet-oxidized hemicellulose hydrolysate was not satisfactory. The bacterium was adapted by isolation of mutant strains, now resistant to the inhibitory compounds present in the hydrolysate. Growth and ethanol yield

  11. Undecylenic Acid Inhibits Morphogenesis of Candida albicans

    OpenAIRE

    McLain, Nealoo; Ascanio, Rhoda; Baker, Carol; Strohaver, Robert A.; Dolan, Joseph W.

    2000-01-01

    Resilient liners are frequently used to treat denture stomatitis, a condition often associated with Candida albicans infections. Of 10 liners tested, 2 were found to inhibit the switch from the yeast form to hyphae and a third was found to stimulate this switch. The inhibitor was determined to be undecylenic acid.

  12. Undecylenic acid inhibits morphogenesis of Candida albicans.

    Science.gov (United States)

    McLain, N; Ascanio, R; Baker, C; Strohaver, R A; Dolan, J W

    2000-10-01

    Resilient liners are frequently used to treat denture stomatitis, a condition often associated with Candida albicans infections. Of 10 liners tested, 2 were found to inhibit the switch from the yeast form to hyphae and a third was found to stimulate this switch. The inhibitor was determined to be undecylenic acid.

  13. Growth-dependent secretome of Candida utilis

    NARCIS (Netherlands)

    Buerth, C.; Heilmann, C.J.; Klis, F.M.; de Koster, C.G.; Ernst, J.F.; Tielker, D.

    2011-01-01

    Recently, the food yeast Candida utilis has emerged as an excellent host for production of heterologous proteins. Since secretion of the recombinant product is advantageous for its purification, we characterized the secreted proteome of C. utilis. Cells were cultivated to the exponential or

  14. New Protocol Based on UHPLC-MS/MS for Quantitation of Metabolites in Xylose-Fermenting Yeasts

    Science.gov (United States)

    Campos, Christiane Gonçalves; Veras, Henrique César Teixeira; de Aquino Ribeiro, José Antônio; Costa, Patrícia Pinto Kalil Gonçalves; Araújo, Katiúscia Pereira; Rodrigues, Clenilson Martins; de Almeida, João Ricardo Moreira; Abdelnur, Patrícia Verardi

    2017-12-01

    Xylose fermentation is a bottleneck in second-generation ethanol production. As such, a comprehensive understanding of xylose metabolism in naturally xylose-fermenting yeasts is essential for prospection and construction of recombinant yeast strains. The objective of the current study was to establish a reliable metabolomics protocol for quantification of key metabolites of xylose catabolism pathways in yeast, and to apply this protocol to Spathaspora arborariae. Ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) was used to quantify metabolites, and afterwards, sample preparation was optimized to examine yeast intracellular metabolites. S. arborariae was cultivated using xylose as a carbon source under aerobic and oxygen-limited conditions. Ion pair chromatography (IPC) and hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) were shown to efficiently quantify 14 and 5 metabolites, respectively, in a more rapid chromatographic protocol than previously described. Thirteen and eleven metabolites were quantified in S. arborariae under aerobic and oxygen-limited conditions, respectively. This targeted metabolomics protocol is shown here to quantify a total of 19 metabolites, including sugars, phosphates, coenzymes, monosaccharides, and alcohols, from xylose catabolism pathways (glycolysis, pentose phosphate pathway, and tricarboxylic acid cycle) in yeast. Furthermore, to our knowledge, this is the first time that intracellular metabolites have been quantified in S. arborariae after xylose consumption. The results indicated that fine control of oxygen levels during fermentation is necessary to optimize ethanol production by S. arborariae. The protocol presented here may be applied to other yeast species and could support yeast genetic engineering to improve second generation ethanol production. [Figure not available: see fulltext.

  15. Proteomic analysis of the secretory response of Aspergillus niger to D-maltose and D-xylose.

    Science.gov (United States)

    de Oliveira, José Miguel P Ferreira; van Passel, Mark W J; Schaap, Peter J; de Graaff, Leo H

    2011-01-01

    Fungi utilize polysaccharide substrates through extracellular digestion catalyzed by secreted enzymes. Thus far, protein secretion by the filamentous fungus Aspergillus niger has mainly been studied at the level of individual proteins and by genome and transcriptome analyses. To extend these studies, a complementary proteomics approach was applied with the aim to investigate the changes in secretome and microsomal protein composition resulting from a shift to a high level secretion condition. During growth of A. niger on D-sorbitol, small amounts of D-maltose or D-xylose were used as inducers of the extracellular amylolytic and xylanolytic enzymes. Upon induction, protein compositions in the extracellular broth as well as in enriched secretory organelle (microsomal) fractions were analyzed using a shotgun proteomics approach. In total 102 secreted proteins and 1,126 microsomal proteins were identified in this study. Induction by D-maltose or D-xylose resulted in the increase in specific extracellular enzymes, such as glucoamylase A on D-maltose and β-xylosidase D on D-xylose, as well as of microsomal proteins. This reflects the differential expression of selected genes coding for dedicated extracellular enzymes. As expected, the addition of extra D-sorbitol had no effect on the expression of carbohydrate-active enzymes, compared to addition of D-xylose or D-maltose. Furthermore, D-maltose induction caused an increase in microsomal proteins related to translation (e.g., Rpl15) and vesicular transport (e.g., the endosomal-cargo receptor Erv14). Millimolar amounts of the inducers D-maltose and D-xylose are sufficient to cause a direct response in specific protein expression levels. Also, after induction by D-maltose or D-xylose, the induced enzymes were found in microsomes and extracellular. In agreement with our previous findings for D-xylose induction, D-maltose induction leads to recruitment of proteins involved in proteasome-mediated degradation.

  16. Proteomic analysis of the secretory response of Aspergillus niger to D-maltose and D-xylose.

    Directory of Open Access Journals (Sweden)

    José Miguel P Ferreira de Oliveira

    Full Text Available Fungi utilize polysaccharide substrates through extracellular digestion catalyzed by secreted enzymes. Thus far, protein secretion by the filamentous fungus Aspergillus niger has mainly been studied at the level of individual proteins and by genome and transcriptome analyses. To extend these studies, a complementary proteomics approach was applied with the aim to investigate the changes in secretome and microsomal protein composition resulting from a shift to a high level secretion condition. During growth of A. niger on D-sorbitol, small amounts of D-maltose or D-xylose were used as inducers of the extracellular amylolytic and xylanolytic enzymes. Upon induction, protein compositions in the extracellular broth as well as in enriched secretory organelle (microsomal fractions were analyzed using a shotgun proteomics approach. In total 102 secreted proteins and 1,126 microsomal proteins were identified in this study. Induction by D-maltose or D-xylose resulted in the increase in specific extracellular enzymes, such as glucoamylase A on D-maltose and β-xylosidase D on D-xylose, as well as of microsomal proteins. This reflects the differential expression of selected genes coding for dedicated extracellular enzymes. As expected, the addition of extra D-sorbitol had no effect on the expression of carbohydrate-active enzymes, compared to addition of D-xylose or D-maltose. Furthermore, D-maltose induction caused an increase in microsomal proteins related to translation (e.g., Rpl15 and vesicular transport (e.g., the endosomal-cargo receptor Erv14. Millimolar amounts of the inducers D-maltose and D-xylose are sufficient to cause a direct response in specific protein expression levels. Also, after induction by D-maltose or D-xylose, the induced enzymes were found in microsomes and extracellular. In agreement with our previous findings for D-xylose induction, D-maltose induction leads to recruitment of proteins involved in proteasome-mediated degradation.

  17. Dynamics of Mixed- Candida Species Biofilms in Response to Antifungals.

    Science.gov (United States)

    Vipulanandan, G; Herrera, M; Wiederhold, N P; Li, X; Mintz, J; Wickes, B L; Kadosh, D

    2018-01-01

    Oral infections caused by Candida species, the most commonly isolated human fungal pathogen, are frequently associated with biofilms. Although Candida albicans is the predominant organism found in patients with oral thrush, a biofilm infection, there is an increasing incidence of oral colonization and infections caused by non- albicans Candida species, including C. glabrata, C. dubliniensis, and C. tropicalis, which are frequently more resistant to antifungal treatment. While single-species Candida biofilms have been well studied, considerably less is known about the dynamics of mixed- Candida species biofilms and how these dynamics are altered by antifungal treatment. To address these questions, we developed a quantitative polymerase chain reaction-based approach to determine the precise species composition of mixed- Candida species biofilms formed by clinical isolates and laboratory strains in the presence and absence of clinically relevant concentrations of 3 commonly used antifungals: fluconazole, caspofungin, and amphotericin B. In monospecies biofilms, fluconazole exposure favored growth of C. glabrata and C. tropicalis, while caspofungin generally favored significant growth of all species to a varying degree. Fluconazole was not effective against preformed mixed- Candida species biofilms while amphotericin B was potent. As a general trend, in mixed- Candida species biofilms, C. albicans lost dominance in the presence of antifungals. Interestingly, presence in mixed versus monospecies biofilms reduced susceptibility to amphotericin B for C. tropicalis and C. glabrata. Overall, our data suggest that antifungal treatment favors the growth of specific non- albicans Candida species in mixed- Candida species biofilms.

  18. Synthesis of furfural from xylose, xylan, and biomass using AlCl3·6H2O in biphasic media via xylose isomerization to xylulose.

    Science.gov (United States)

    Yang, Yu; Hu, Chang-Wei; Abu-Omar, Mahdi M

    2012-02-13

    Furfural was prepared in high yields (75 %) from the reaction of xylose in a water-tetrahydrofuran biphasic medium containing AlCl(3)·6H2O and NaCl under microwave heating at 140 °C. The reaction profile revealed the formation of xylulose as an intermediate en route to the dehydration product (furfural). The reaction under these conditions reached completion in 45 min. The aqueous phase containing AlCl(3)·6H(2)O and NaCl could be recycled multiple times (>5) without any loss of activity or selectivity for furfural. Extension of this biphasic reaction system to include xylan as the starting material afforded furfural in 64 % yield. The use of corn stover, pinewood, switchgrass, and poplar gave furfural in 55, 38, 56, and 64 % yield, respectively, at 160 °C. Even though AlCl(3)·6H(2)O did not affect the conversion of crystalline cellulose, moderate yields of the by-product 5-hydroxymethylfurfural (HMF) were noted. The highest HMF yield of 42 % was obtained from pinewood. The coproduction of HMF and furfural from biomass was attributed to the weakening of the cellulose network in the biomass, as a result of hemicellulose hydrolysis. The multifunctional capacity of AlCl(3)·6H(2)O (hemicellulose hydrolysis, xylose isomerization, and xylulose dehydration) in combination with its ease of recyclability make it an attractive candidate/catalyst for the selective synthesis of furfural from various biomass feedstocks. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Separate hydrolysis and co-fermentation for improved xylose utilization in integrated ethanol production from wheat meal and wheat straw

    Directory of Open Access Journals (Sweden)

    Erdei Borbála

    2012-03-01

    Full Text Available Abstract Background The commercialization of second-generation bioethanol has not been realized due to several factors, including poor biomass utilization and high production cost. It is generally accepted that the most important parameters in reducing the production cost are the ethanol yield and the ethanol concentration in the fermentation broth. Agricultural residues contain large amounts of hemicellulose, and the utilization of xylose is thus a plausible way to improve the concentration and yield of ethanol during fermentation. Most naturally occurring ethanol-fermenting microorganisms do not utilize xylose, but a genetically modified yeast strain, TMB3400, has the ability to co-ferment glucose and xylose. However, the xylose uptake rate is only enhanced when the glucose concentration is low. Results Separate hydrolysis and co-fermentation of steam-pretreated wheat straw (SPWS combined with wheat-starch hydrolysate feed was performed in two separate processes. The average yield of ethanol and the xylose consumption reached 86% and 69%, respectively, when the hydrolysate of the enzymatically hydrolyzed (18.5% WIS unwashed SPWS solid fraction and wheat-starch hydrolysate were fed to the fermentor after 1 h of fermentation of the SPWS liquid fraction. In the other configuration, fermentation of the SPWS hydrolysate (7.0% WIS, resulted in an average ethanol yield of 93% from fermentation based on glucose and xylose and complete xylose consumption when wheat-starch hydrolysate was included in the feed. Increased initial cell density in the fermentation (from 5 to 20 g/L did not increase the ethanol yield, but improved and accelerated xylose consumption in both cases. Conclusions Higher ethanol yield has been achieved in co-fermentation of xylose and glucose in SPWS hydrolysate when wheat-starch hydrolysate was used as feed, then in co-fermentation of the liquid fraction of SPWS fed with the mixed hydrolysates. Integration of first-generation and

  20. PRODUCCIÓN DE XILITOL A PARTIR DE CASCARILLA DE ARROZ UTILIZANDO Candida guilliermondii XYLITOL PRODUCTION FROM RICE HUSK USING Candida guilliermondii

    Directory of Open Access Journals (Sweden)

    Marcela Villalba Cadavid

    2009-06-01

    Full Text Available En este estudio se empleó cascarilla de arroz como materia prima para la obtención de xilitol, previa hidrólisis durante 60 minutos con ácido sulfúrico al 4% p/v; a 121 ºC y 15 psig,; La xilosa producida se transformó en xilitol mediante su fermentación con Candida guilliermondii. Se estudió el efecto de las variables concentración inicial de xilosa, concentración de inóculo y relación volumen del medio/volumen del matraz, así como sus efectos combinados, sobre la producción de xilitol. Se encontró que las concentraciones iniciales de xilosa e inóculo más adecuadas, entre los valores ensayados, fueron 80 y 5,0 g/l, respectivamente. En estas condiciones, la concentración final de xilitol obtenida fue de 45,2 g/l, con una productividad volumétrica de 0,23 g/l•h y un rendimiento de 0,57 g/g.In this study was used rice husk, previosly hydrolyzed with diluted sulfuric acid at 121 ºC and 15 psig, with a residence time 60 min. The initial concentration of substrate, inoculum, and relationship between media volume/flask volume and their combined effects were studied on the production of xylitol. The initial concentrations of 80 g/l xylose and 5 g/l inoculums led the best xylitol production (45.2 g/l, productivity (0.23 g/l•h and yield (0.57 g/g.

  1. Inhibitor tolerance of a recombinant flocculating industrial Saccharomyces cerevisiae strain during glucose and xylose co-fermentation

    Directory of Open Access Journals (Sweden)

    Yun-Cheng Li

    Full Text Available ABSTRACT Lignocellulose-derived inhibitors have negative effects on the ethanol fermentation capacity of Saccharomyces cerevisiae. In this study, the effects of eight typical inhibitors, including weak acids, furans, and phenols, on glucose and xylose co-fermentation of the recombinant xylose-fermenting flocculating industrial S. cerevisiae strain NAPX37 were evaluated by batch fermentation. Inhibition on glucose fermentation, not that on xylose fermentation, correlated with delayed cell growth. The weak acids and the phenols showed additive effects. The effect of inhibitors on glucose fermentation was as follows (from strongest to weakest: vanillin > phenol > syringaldehyde > 5-HMF > furfural > levulinic acid > acetic acid > formic acid. The effect of inhibitors on xylose fermentation was as follows (from strongest to weakest: phenol > vanillin > syringaldehyde > furfural > 5-HMF > formic acid > levulinic acid > acetic acid. The NAPX37 strain showed substantial tolerance to typical inhibitors and showed good fermentation characteristics, when a medium with inhibitor cocktail or rape straw hydrolysate was used. This research provides important clues for inhibitors tolerance of recombinant industrial xylose-fermenting S. cerevisiae.

  2. Time-based comparative transcriptomics in engineered xylose-utilizing Saccharomyces cerevisiae identifies temperature-responsive genes during ethanol production.

    Science.gov (United States)

    Ismail, Ku Syahidah Ku; Sakamoto, Takatoshi; Hasunuma, Tomohisa; Kondo, Akihiko

    2013-09-01

    Agricultural residues comprising lignocellulosic materials are excellent sources of pentose sugar, which can be converted to ethanol as fuel. Ethanol production via consolidated bioprocessing requires a suitable microorganism to withstand the harsh fermentation environment of high temperature, high ethanol concentration, and exposure to inhibitors. We genetically enhanced an industrial Saccharomyces cerevisiae strain, sun049, enabling it to uptake xylose as the sole carbon source at high fermentation temperature. This strain was able to produce 13.9 g/l ethanol from 50 g/l xylose at 38 °C. To better understand the xylose consumption ability during long-term, high-temperature conditions, we compared by transcriptomics two fermentation conditions: high temperature (38 °C) and control temperature (30 °C) during the first 12 h of fermentation. This is the first long-term, time-based transcriptomics approach, and it allowed us to discover the role of heat-responsive genes when xylose is the sole carbon source. The results suggest that genes related to amino acid, cell wall, and ribosomal protein synthesis are down-regulated under heat stress. To allow cell stability and continuous xylose uptake in order to produce ethanol, hexose transporter HXT5, heat shock proteins, ubiquitin proteins, and proteolysis were all induced at high temperature. We also speculate that the strong relationship between high temperature and increased xylitol accumulation represents the cell's mechanism to protect itself from heat degradation.

  3. Fermentation of Xylose Causes Inefficient Metabolic State Due to Carbon/Energy Starvation and Reduced Glycolytic Flux in Recombinant Industrial Saccharomyces cerevisiae

    Science.gov (United States)

    Matsushika, Akinori; Nagashima, Atsushi; Goshima, Tetsuya; Hoshino, Tamotsu

    2013-01-01

    In the present study, comprehensive, quantitative metabolome analysis was carried out on the recombinant glucose/xylose-cofermenting S. cerevisiae strain MA-R4 during fermentation with different carbon sources, including glucose, xylose, or glucose/xylose mixtures. Capillary electrophoresis time-of-flight mass spectrometry was used to determine the intracellular pools of metabolites from the central carbon pathways, energy metabolism pathways, and the levels of twenty amino acids. When xylose instead of glucose was metabolized by MA-R4, glycolytic metabolites including 3- phosphoglycerate, 2- phosphoglycerate, phosphoenolpyruvate, and pyruvate were dramatically reduced, while conversely, most pentose phosphate pathway metabolites such as sedoheptulose 7- phosphate and ribulose 5-phosphate were greatly increased. These results suggest that the low metabolic activity of glycolysis and the pool of pentose phosphate pathway intermediates are potential limiting factors in xylose utilization. It was further demonstrated that during xylose fermentation, about half of the twenty amino acids declined, and the adenylate/guanylate energy charge was impacted due to markedly decreased adenosine triphosphate/adenosine monophosphate and guanosine triphosphate/guanosine monophosphate ratios, implying that the fermentation of xylose leads to an inefficient metabolic state where the biosynthetic capabilities and energy balance are severely impaired. In addition, fermentation with xylose alone drastically increased the level of citrate in the tricarboxylic acid cycle and increased the aromatic amino acids tryptophan and tyrosine, strongly supporting the view that carbon starvation was induced. Interestingly, fermentation with xylose alone also increased the synthesis of the polyamine spermidine and its precursor S-adenosylmethionine. Thus, differences in carbon substrates, including glucose and xylose in the fermentation medium, strongly influenced the dynamic metabolism of MA-R4

  4. Candida krusei and Candida glabrata reduce the filamentation of Candida albicans by downregulating expression of HWP1 gene.

    Science.gov (United States)

    de Barros, Patrícia Pimentel; Freire, Fernanda; Rossoni, Rodnei Dennis; Junqueira, Juliana Campos; Jorge, Antonio Olavo Cardoso

    2017-07-01

    Pathogenicity of Candida albicans is associated with its capacity switch from yeast-like to hyphal growth. The hyphal form is capable to penetrate the epithelial surfaces and to damage the host tissues. Therefore, many investigations have focused on mechanisms that control the morphological transitions of C. albicans. Recently, certain studies have showed that non-albicans Candida species can reduce the capacity of C. albicans to form biofilms and to develop candidiasis in animal models. Then, the objective of this study was to evaluate the effects of Candida krusei and Candida glabrata on the morphogenesis of C. albicans. Firstly, the capacity of reference and clinical strains of C. albicans in forming hyphae was tested in vitro. After that, the expression of HWP1 (hyphal wall protein 1) gene was determined by quantitative real-time PCR (polymerase chain reaction) assay. For both reference and clinical strains, a significant inhibition of the hyphae formation was observed when C. albicans was incubated in the presence of C. krusei or C. glabrata compared to the control group composed only by C. albicans. In addition, the culture mixed of C. albicans-C. krusei or C. albicans-C. glabrata reduced significantly the expression of HWP1 gene of C. albicans in relation to single cultures of this specie. In both filamentation and gene expression assays, C. krusei showed the higher inhibitory activity on the morphogenesis of C. albicans compared to C. glabrata. C. krusei and C. glabrata are capable to reduce the filamentation of C. albicans and consequently decrease the expression of the HWP1 gene.

  5. D-Xylose fermentation, xylitol production and xylanase activities by seven new species of Sugiyamaella.

    Science.gov (United States)

    Sena, Letícia M F; Morais, Camila G; Lopes, Mariana R; Santos, Renata O; Uetanabaro, Ana P T; Morais, Paula B; Vital, Marcos J S; de Morais, Marcos A; Lachance, Marc-André; Rosa, Carlos A

    2017-01-01

    Sixteen yeast isolates identified as belonging to the genus Sugiyamaella were studied in relation to D-xylose fermentation, xylitol production, and xylanase activities. The yeasts were recovered from rotting wood and sugarcane bagasse samples in different Brazilian regions. Sequence analyses of the internal transcribed spacer (ITS) region and the D1/D2 domains of large subunit rRNA gene showed that these isolates belong to seven new species. The species are described here as Sugiyamaella ayubii f.a., sp. nov. (UFMG-CM-Y607 T  = CBS 14108 T ), Sugiyamaella bahiana f.a., sp. nov. (UFMG-CM-Y304 T  = CBS 13474 T ), Sugiyamaella bonitensis f.a., sp. nov. (UFMG-CM-Y608 T  = CBS 14270 T ), Sugiyamaella carassensis f.a., sp. nov. (UFMG-CM-Y606 T  = CBS 14107 T ), Sugiyamaella ligni f.a., sp. nov. (UFMG-CM-Y295 T  = CBS 13482 T ), Sugiyamaella valenteae f.a., sp. nov. (UFMG-CM-Y609 T  = CBS 14109 T ) and Sugiyamaella xylolytica f.a., sp. nov. (UFMG-CM-Y348 T  = CBS 13493 T ). Strains of the described species S. boreocaroliniensis, S. lignohabitans, S. novakii and S. xylanicola, isolated from rotting wood of Brazilian ecosystems, were also compared for traits relevant to xylose metabolism. S. valenteae sp. nov., S. xylolytica sp. nov., S. bahiana sp. nov., S. bonitensis sp. nov., S. boreocarolinensis, S. lignohabitans and S. xylanicola were able to ferment D-xylose to ethanol. Xylitol production was observed for all Sugiyamaella species studied, except for S. ayubii sp. nov. All species studied showed xylanolytic activity, with S. xylanicola, S. lignohabitans and S. valenteae sp. nov. having the highest values. Our results suggest these Sugiyamaella species have good potential for biotechnological applications.

  6. The determination of optimal cells disintegration method of Candida albicans and Candida tropicalis fungals

    Directory of Open Access Journals (Sweden)

    M. V. Rybalkyn

    2014-08-01

    Full Text Available Candidiasis is common infectious disease that affects the mucous membranes, skin, nails, hair, and internal organs. Now Ukraine has neither domestic nor registered imported vaccine against candidiasis. The development of vaccine for prevention and treatment of candidiasis is a key issue in modern medicine and pharmacy. Similar research is actively conducted in many countries of the world: Russia, USA, Japan and others. It should be noted that researchers have not yet reached a consensus view which vaccine is most effective with candidiasis. There are several types of vaccines: live, inactivated, subunit and others. In this article, we consider getting the potential subunit vaccine from Candida albicans and Candida tropicalis fungi. Subunit vaccine is composed of fragments of antigens that can provide an adequate immune response. These vaccines can be represented by particles of microbes. It is known that the main substances in cells of genus Candida fungi, which have antigenic properties, are proteins and polysaccharides. However, the question of their localization in the layers of the cell wall and cytoplasm nowadays require more detailed studies. Many researchers to highlight cytoplasm antigens and all the other layers of the cell use the following methods: grinding cells with quartz sand, destroying them in different machine disintegrating, freezing and thawing a multi others. To obtain potential subunit vaccine fungi were rejected by methods that are based on the processing of biomass fungi chemicals (extraction, hydrolysis. The aim of this work was to study experimentally the destruction method of Candida albicans and Candida tropicalis fungi. Cells of Candida albicans fungi strain CCM 335-867 and Candida tropicalis fungi strain 20336 ATTS have been separately cultured in vitro on agar Sabouraud at 25 ± 2º C for 48 hours and then washed by 10 ml of sterile 0.9% isotonic sodium chloride solution. Cell suspension of Candida albicans and

  7. Effect of humic acids on electricity generation integrated with xylose degradation in microbial fuel cells

    DEFF Research Database (Denmark)

    Huang, Liping; Angelidaki, Irini

    2008-01-01

    Pentose and humic acids (HA) are the main components of hydrolysates, the liquid fraction produced during thermohydrolysis of lignocellulosic material. Electricity generation integrated with xylose (typical pentose) degradation as well as the effect of HA on electricity production in microbial fuel...... to controls where HAs were not added, addition of commercial HA resulted in increase of power density and coulombic efficiency, which ranged from 7.5% to 67.4% and 24% to 92.6%, respectively. Digested manure wastewater (DMW) was tested as potential mediator for power generation due to its content of natural...

  8. Breeding L(+)-lactic acid high productive mutant from xylose by nitrogen ions

    International Nuclear Information System (INIS)

    Yang Yingge; Li Wen; Liu Dan; Fan Yonghong; Wang Dongmei; Zheng Zhiming; Yu Zengliang

    2007-01-01

    In order to obtain higher L(+)-lactic acid yield strain fermentating from xylose, the original strain Rhizopus oryzae RLC41-6 was mutated by 10keV N + ion implantation. A mutant strain RQ4012 was obtained. After 72h shake-flask cultivation, the concentration of L(+)-lactic acid reached 74.37g/L, and the productivity was 1.03g/(L.h). Its lactic acid yield was 160% higher than that of the original one, and the mutant strain has high genetic stability. (authors)

  9. Effect of xylose and nutrients concentration on ethanol production by a newly isolated extreme thermophilic bacterium

    DEFF Research Database (Denmark)

    Tomás, Ana Faria; Karakashev, Dimitar Borisov; Angelidaki, Irini

    2011-01-01

    An extreme thermophilic ethanol-producing strain was isolated from an ethanol high-yielding mixed culture, originally isolated from a hydrogen producing reactor operated at 70 °C. Ethanol yields were assessed with increasing concentrations of xylose, up to 20 g/l. The ability of the strain to gro...... product under most of the conditions tested, including in media lacking vitamins, peptone and yeast extract. The results indicate that this new organism is a promising candidate for the development of a second generation bio-ethanol production process. © IWA Publishing 2011....

  10. Relationship between salivary flow rates and Candida albicans counts.

    Science.gov (United States)

    Navazesh, M; Wood, G J; Brightman, V J

    1995-09-01

    Seventy-one persons (48 women, 23 men; mean age, 51.76 years) were evaluated for salivary flow rates and Candida albicans counts. Each person was seen on three different occasions. Samples of unstimulated whole, chewing-stimulated whole, acid-stimulated parotid, and candy-stimulated parotid saliva were collected under standardized conditions. An oral rinse was also obtained and evaluated for Candida albicans counts. Unstimulated and chewing-stimulated whole flow rates were negatively and significantly (p Candida counts. Unstimulated whole saliva significantly (p Candida counts of 0 versus or = 500 count. Differences in stimulated parotid flow rates were not significant among different levels of Candida counts. The results of this study reveal that whole saliva is a better predictor than parotid saliva in identification of persons with high Candida albicans counts.

  11. Azasordarins: Susceptibility of Fluconazole-Susceptible and Fluconazole-Resistant Clinical Isolates of Candida spp. to GW 471558

    OpenAIRE

    Cuenca-Estrella, Manuel; Mellado, Emilia; Díaz-Guerra, Teresa M.; Monzón, Araceli; Rodríguez-Tudela, Juan L.

    2001-01-01

    The in vitro activity of the azasordarin GW 471558 was compared with those of amphotericin B, flucytosine, itraconazole, and ketoconazole against 177 clinical isolates of Candida spp. GW 471558 showed potent activity against Candida albicans, Candida glabrata, and Candida tropicalis, even against isolates with decreased susceptibility to azoles. Candida krusei, Candida parapsilosis, Candida lusitaniae, and Candida guilliermondii are resistant to GW 471558 in vitro (MICs, >128 μg/ml).

  12. Metabolic characterization and transformation of the non-dairy Lactococcus lactis strain KF147, for production of ethanol from xylose

    DEFF Research Database (Denmark)

    Petersen, Kia Vest; Liu, Jianming; Chen, Jun

    2017-01-01

    producing ethanol as the sole fermentation product with a high yield corresponding to 83% of the theoretical maximum. The results clearly indicate the great potential of using the more metabolically diverse non-dairy L. lactis strains for bio-production based on xylose containing feedstocks.......The non-dairy lactic acid bacterium Lactococcus lactis KF147 can utilize xylose as the sole energy source. To assess whether KF147 could serve as a platform organism for converting second generation sugars into useful chemicals, we characterized growth and product formation for KF147 when grown...... the arcA gene encoding the arginine deiminase. The fermentation product profile suggested two routes for xylose degradation, the phosphoketolase pathway and the pentose phosphate pathway. Inactivation of the phosphoketolase pathway redirected the entire flux through the pentose phosphate pathway whereas...

  13. with Candida spp. aetiology in women

    Directory of Open Access Journals (Sweden)

    Hanna Tomczak

    2014-08-01

    Full Text Available Urinary tract infections (UTIs in women are a growing clinical concern. The most frequent risk factors of UTIs with fungal aetiology in women are: antibiotic therapy (especially broad-spectrum antibiotics, immunosuppressive therapy, diabetes, malnutrition, pregnancy, and frequent intercourse. The aim of the study was to analyse urinary tract infections with Candida spp. aetiology in women hospitalised at the Clinical Hospital in Poznań, Poland, between 2009 and 2011. The investigations revealed that as many as 71% of positive urine cultures with Candida fungi came from women. The following fungi were most frequently isolated from the patients under analysis: C. albicans (47%, C. glabrata (31%, C. tropicalis (6%, C. krusei (3%. In order to diagnose a UTI the diagnosis cannot be based on a single result of a urine culture. Due to the small number of antifungal drugs and high costs of treatment, antifungal drugs should be applied with due consideration and care.

  14. Candida Biofilms: Development, Architecture, and Resistance

    Science.gov (United States)

    CHANDRA, JYOTSNA; MUKHERJEE, PRANAB K.

    2015-01-01

    Intravascular device–related infections are often associated with biofilms (microbial communities encased within a polysaccharide-rich extracellular matrix) formed by pathogens on the surfaces of these devices. Candida species are the most common fungi isolated from catheter-, denture-, and voice prosthesis–associated infections and also are commonly isolated from contact lens–related infections (e.g., fungal keratitis). These biofilms exhibit decreased susceptibility to most antimicrobial agents, which contributes to the persistence of infection. Recent technological advances have facilitated the development of novel approaches to investigate the formation of biofilms and identify specific markers for biofilms. These studies have provided extensive knowledge of the effect of different variables, including growth time, nutrients, and physiological conditions, on biofilm formation, morphology, and architecture. In this article, we will focus on fungal biofilms (mainly Candida biofilms) and provide an update on the development, architecture, and resistance mechanisms of biofilms. PMID:26350306

  15. Candida infection in oral leukoplakia: an unperceived public health problem.

    Science.gov (United States)

    Dilhari, Ayomi; Weerasekera, Manjula M; Siriwardhana, Anusha; Maheshika, Oshanthi; Gunasekara, Chinthika; Karunathilaka, Sunil; Nagahawatte, Ajith; Fernando, Neluka

    2016-10-01

    The study aimed to determine the proportion, known risk factors and etiology for Candida infection in leukoplakia lesions among patients with oral leukoplakia attending the Oral and Maxillofacial Clinic at a Tertiary Care Hospital in Sri Lanka. Eighty clinically suspected oral leukoplakia patients were included. Two oral swabs each, from leukoplakia patients: one swab from the lesion and the other one from the contralateral unaffected corresponding area (as a control) were collected. Direct microscopy and culture followed by colony count and phenotypic identification were performed to identify pathogenic Candida species. Candida infection was seen in 47% of patients with oral leukoplakia. Candida albicans (94.7%) was the most common Candida species followed by Candida tropicalis (5.3%). Majority of Candida-infected lesions were seen in the buccal mucosa region. Alteration of taste (p = 0.021), having other oral lesions (p = 0.008), angular cheilitis (p = 0.024) and periodontitis (p = 0.041) showed a significant association with Candida-associated leukoplakia. Increasing age showed a significant tendency for Candida infection (p = 0.020). Smoking (p = 0.026) and betel-quid chewing (p = 0.006) were also found to be significantly associated, although alcohol consumption alone did not show a significant association. Oral leukoplakia patients who had all three habits: alcohol consumption, smoking and betel-quid chewing had a significant association with Candida infection (p = 0.004). Patients who had a combination of risk factors: smoking, betel-quid chewing and alcohol consumption were seen to have a significant association with Candida infection. Further betel-quid chewing alone and smoking singly was also significantly associated with Candida infection in oral leukoplakia.

  16. Candida albicans importance to denture wearers. A literature review.

    Science.gov (United States)

    Gleiznys, Alvydas; Zdanavičienė, Eglė; Žilinskas, Juozas

    2015-01-01

    Opportunistic oral fungal infections have spred, especially in denture wearers. Denture stomatitis is a common inflammatory reaction, multifactorial etiology, which is usually associated with Candida species, particularly Candida albicans, due to its high virulence, ability to adhere and form biofilms on oral cavity tissues and denture surfaces. This article highlights the pathogenesis, clinical presentation, and management strategies of Candida-associated denture stomatitis commonly encountered in dental practice.

  17. Process for assembly and transformation into Saccharomyces cerevisiae of a synthetic yeast artificial chromosome containing a multigene cassette to express enzymes that enhance xylose utilization designed for an automated pla

    Science.gov (United States)

    A yeast artificial chromosome (YAC) containing a multigene cassette for expression of enzymes that enhance xylose utilization (xylose isomerase [XI] and xylulokinase [XKS]) was constructed and transformed into Saccharomyces cerevisiae to demonstrate feasibility as a stable protein expression system ...

  18. Candida famata-induced fulminating cholecystitis

    Directory of Open Access Journals (Sweden)

    Paulo Sergio Ramos de Araujo

    2013-12-01

    Full Text Available Lithiasic cholecystitis is classically associated with the presence of enterobacteria, such as Escherichia coli, Enterococcus, Klebsiella, and Enterobacter, in the gallbladder. Cholecystitis associated with fungal infections is a rare event related to underlying conditions such as diabetes mellitus, steroid use, and broad-spectrum antibiotic use for prolonged periods, as well as pancreatitis and surgery of the digestive tract. Here, we present the first reported case of a gallbladder infection caused by Candida famata.

  19. Candida parapsilosis Biofilm Identification by Raman Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Samek, Ota; Mlynariková, K.; Bernatová, Silvie; Ježek, Jan; Krzyžánek, Vladislav; Šiler, Martin; Zemánek, Pavel; Růžička, F.; Holá, Miroslava; Mahelová, M.

    2014-01-01

    Roč. 15, č. 12 (2014), s. 23924-23935 E-ISSN 1422-0067 R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01; GA ČR GAP205/11/1687 Institutional support: RVO:68081731 Keywords : Raman spectroscopy * Candida parapsilosis * biofilm Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.862, year: 2014

  20. Enzymes of Candida tropicalis yeast biodegrading phenol

    OpenAIRE

    Koubková, Zuzana

    2011-01-01

    Effluents of industrial wastewaters from oil refineries, paper mills, dyes, ceramic factories, resins, textiles and plastic contain high concentrations of aromatic compounds, which are toxic to organisms. Degradation of these compounds to tolerant limits before releasing them into the environment is an urgent requirement. Candida tropicalis yeast is an important representative of eucaryotic microorganisms that are able to utilize phenol. During the first phase of phenol biodegradation, cytopl...

  1. Formation of xylitol and xylitol-5-phosphate and its impact on growth of d-xylose-utilizing Corynebacterium glutamicum strains.

    Science.gov (United States)

    Radek, Andreas; Müller, Moritz-Fabian; Gätgens, Jochem; Eggeling, Lothar; Krumbach, Karin; Marienhagen, Jan; Noack, Stephan

    2016-08-10

    Wild-type Corynebacterium glutamicum has no endogenous metabolic activity for utilizing the lignocellulosic pentose d-xylose for cell growth. Therefore, two different engineering approaches have been pursued resulting in platform strains harbouring a functional version of either the Isomerase (ISO) or the Weimberg (WMB) pathway for d-xylose assimilation. In a previous study we found for C. glutamicum WMB by-product formation of xylitol during growth on d-xylose and speculated that the observed lower growth rates are due to the growth inhibiting effect of this compound. Based on a detailed phenotyping of the ISO, WMB and the wild-type strain of C. glutamicum, we here show that this organism has a natural capability to synthesize xylitol from d-xylose under aerobic cultivation conditions. We furthermore observed the intracellular accumulation of xylitol-5-phosphate as a result of the intracellular phosphorylation of xylitol, which was particularly pronounced in the C. glutamicum ISO strain. Interestingly, low amounts of supplemented xylitol strongly inhibit growth of this strain on d-xylose, d-glucose and d-arabitol. These findings demonstrate that xylitol is a suitable substrate of the endogenous xylulokinase (XK, encoded by xylB) and its overexpression in the ISO strain leads to a significant phosphorylation of xylitol in C. glutamicum. Therefore, in order to circumvent cytotoxicity by xylitol-5-phosphate, the WMB pathway represents an interesting alternative route for engineering C. glutamicum towards efficient d-xylose utilization. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Study on the Requirement of Nitrogen Sources by Scheffersomyces Stipitis NRRL Y-7124 to Produce Ethanol from Xylose Based-media

    DEFF Research Database (Denmark)

    Mussatto, Solange I.; Carneiro, L. M.; Roberto, I. C.

    This study aimed at evaluating the requirement of nitrogen sources by the yeast Scheffersomyces stipitis NRRL Y-7124 to produce ethanol from xylose based-media. Different nitrogen sources were evaluated, which were used to supplement a defined xylose-based medium and also the hemicellulosic hydro...

  3. Candida albicans response to spaceflight (NASA STS-115)

    Data.gov (United States)

    National Aeronautics and Space Administration — This study presents the first global transcriptional profiling and phenotypic characterization of the major human opportunistic fungal pathogen Candida albicans...

  4. Biosorption of 241Am by Candida sp

    International Nuclear Information System (INIS)

    Luo Shunzhong; Zhang Taiming; Liu Ning; Yang Yuanyou; Jin Jiannan; Hua Xinfeng

    2003-01-01

    The biosorption of radionuclide 241 Am from solutions by Candida sp., and the influences of experimental conditions on the adsorption were studied. The results showed that the adsorption equilibrium was achieved within 4h and the optimum pH=2. No significant differences on 241 Am biosorption were observed at 10-45 degree C, or challenged with Au 3+ or Ag + , even 1500 times or 4500 times over 241 Am, respectively. The adsorption rate could reach 97.8% by dry Candida sp. of 0.82 g/L in 241 Am solutions (pH=2) of 5.6-111 MBq/L (44.04-873.0 μg/L) (C 0 ), with maximum adsorption capacity (W) of 63.5 MBq/g (501.8 μg/g), implying that the removal of 241 Am by Candida sp. from solutions was feasible. The relationship between activities (C 0 ) and adsorption capacities (W) of 241 Am indicated that the biosorption process could be described by Langmuir adsorption isotherm

  5. Biosorption of americium-241 by Candida sp

    International Nuclear Information System (INIS)

    Luo Shunzhong; Zhang Taiming; Liu Ning; Yang Yuanyou; Jin Jiannan; Liao Jiali

    2003-01-01

    As an important radioisotope in nuclear industry and other fields, americium-241 is one of the most serious contamination concerns duo to its high toxicity and long half-life. In this experiment, the biosorption of 241 Am from solution by Candida sp., and the effects of various experimental conditions on the adsorption were investigated. The preliminary results showed that the adsorption of 241 Am by Candida sp. was efficient. 241 Am could be removed by Candida sp. of 0.82 g/L (dry weight) from 241 Am solutions of 5.6-111 MBq/L (44.3-877.2 μg/L)(C 0 ), with maximum adsorption rate (R) of 98% and maximum adsorption capacities (W) of 63.5 MBq/g biomass (dry weight) (501.8 μg/g). The biosorption equilibrium was achieved within 4 hour and the optimum pH was pH = 2. No significant differences on 241 Am adsorption were observed at 10 C-45 C, or in solutions containing Au 3+ or Ag + , even 1500 times or 4500 times above the 241 Am concentration, respectively. The relationship between concentrations and adsorption capacities of 241 Am indicated the biosorption process should be described by a Langmuir adsorption isotherm. (orig.)

  6. Enzymatic Xylose Release from Pretreated Corn Bran Arabinoxylan: Differential Effects of Deacetylation and Deferuloylation on Insoluble and Soluble Substrate Fractions

    DEFF Research Database (Denmark)

    Agger, Jane; Viksø-Nielsen, Ander; Meyer, Anne S.

    2010-01-01

    In the present work enzymatic hydrolysis of arabinoxylan from pretreated corn bran (190 °C, 10 min) was evaluated by measuring the release of xylose and arabinose after treatment with a designed minimal mixture of monocomponent enzymes consisting of α-l-arabinofuranosidases, an endoxylanase......, and a β-xylosidase. The pretreatment divided the corn bran material 50:50 into soluble and insoluble fractions having A:X ratios of 0.66 and 0.40, respectively. Addition of acetyl xylan esterase to the monocomponent enzyme mixture almost doubled the xylose release from the insoluble substrate fraction...

  7. Evaluation of a kinetic model for computer simulation of growth and fermentation by Scheffersomyces (Pichia) stipitis fed D-xylose.

    Science.gov (United States)

    Slininger, P J; Dien, B S; Lomont, J M; Bothast, R J; Ladisch, M R; Okos, M R

    2014-08-01

    Scheffersomyces (formerly Pichia) stipitis is a potential biocatalyst for converting lignocelluloses to ethanol because the yeast natively ferments xylose. An unstructured kinetic model based upon a system of linear differential equations has been formulated that describes growth and ethanol production as functions of ethanol, oxygen, and xylose concentrations for both growth and fermentation stages. The model was validated for various growth conditions including batch, cell recycle, batch with in situ ethanol removal and fed-batch. The model provides a summary of basic physiological yeast properties and is an important tool for simulating and optimizing various culture conditions and evaluating various bioreactor designs for ethanol production. © 2014 Wiley Periodicals, Inc.

  8. Postantifungal Effect of Micafungin against the Species Complexes of Candida albicans and Candida parapsilosis.

    Directory of Open Access Journals (Sweden)

    Sandra Gil-Alonso

    Full Text Available Micafungin is an effective antifungal agent useful for the therapy of invasive candidiasis. Candida albicans is the most common cause of invasive candidiasis; however, infections due to non-C. albicans species, such as Candida parapsilosis, are rising. Killing and postantifungal effects (PAFE are important factors in both dose interval choice and infection outcome. The aim of this study was to determinate the micafungin PAFE against 7 C. albicans strains, 5 Candida dubliniensis, 2 Candida Africana, 3 C. parapsilosis, 2 Candida metapsilosis and 2 Candida orthopsilosis. For PAFE studies, cells were exposed to micafungin for 1 h at concentrations ranging from 0.12 to 8 μg/ml. Time-kill experiments (TK were conducted at the same concentrations. Samples were removed at each time point (0-48 h and viable counts determined. Micafungin (2 μg/ml was fungicidal (≥ 3 log10 reduction in TK against 5 out of 14 (36% strains of C. albicans complex. In PAFE experiments, fungicidal endpoint was achieved against 2 out of 14 strains (14%. In TK against C. parapsilosis, 8 μg/ml of micafungin turned out to be fungicidal against 4 out 7 (57% strains. Conversely, fungicidal endpoint was not achieved in PAFE studies. PAFE results for C. albicans complex (41.83 ± 2.18 h differed from C. parapsilosis complex (8.07 ± 4.2 h at the highest tested concentration of micafungin. In conclusion, micafungin showed significant differences in PAFE against C. albicans and C. parapsilosis complexes, being PAFE for the C. albicans complex longer than for the C. parapsilosis complex.

  9. Expanding xylose metabolism in yeast for plant cell wall conversion to biofuels

    Science.gov (United States)

    Li, Xin; Yu, Vivian Yaci; Lin, Yuping; Chomvong, Kulika; Estrela, Raíssa; Park, Annsea; Liang, Julie M; Znameroski, Elizabeth A; Feehan, Joanna; Kim, Soo Rin; Jin, Yong-Su; Glass, N Louise; Cate, Jamie HD

    2015-01-01

    Sustainable biofuel production from renewable biomass will require the efficient and complete use of all abundant sugars in the plant cell wall. Using the cellulolytic fungus Neurospora crassa as a model, we identified a xylodextrin transport and consumption pathway required for its growth on hemicellulose. Reconstitution of this xylodextrin utilization pathway in Saccharomyces cerevisiae revealed that fungal xylose reductases act as xylodextrin reductases, producing xylosyl-xylitol oligomers as metabolic intermediates. These xylosyl-xylitol intermediates are generated by diverse fungi and bacteria, indicating that xylodextrin reduction is widespread in nature. Xylodextrins and xylosyl-xylitol oligomers are then hydrolyzed by two hydrolases to generate intracellular xylose and xylitol. Xylodextrin consumption using a xylodextrin transporter, xylodextrin reductases and tandem intracellular hydrolases in cofermentations with sucrose and glucose greatly expands the capacity of yeast to use plant cell wall-derived sugars and has the potential to increase the efficiency of both first-generation and next-generation biofuel production. DOI: http://dx.doi.org/10.7554/eLife.05896.001 PMID:25647728

  10. Aerobic Oxidation of Xylose to Xylaric acid in Water over Pt Catalysts.

    Science.gov (United States)

    Saha, Basudeb; Sadula, Sunitha

    2018-05-02

    Energy-efficient catalytic conversion of biomass intermediates to functional chemicals can enable bio-products viable. Herein, we report an efficient and low temperature aerobic oxidation of xylose to xylaric acid, a promising bio-based chemical for the production of glutaric acid, over commercial catalysts in water. Among several heterogeneous catalysts investigated, Pt/C exhibits the best activity. Systematic variation of reaction parameters in the pH range of 2.5 to 10 suggests that the reaction is fast at higher temperatures but high C-C scission of intermediate C5-oxidized products to low carbon carboxylic acids undermines xylaric acid selectivity. The C-C cleavage is also high in basic solution. The oxidation at neutral pH and 60 C achieves the highest xylaric acid yield (64%). O2 pressure and Pt-amount have significant influence on the reactivity. Decarboxylation of short chain carboxylic acids results in formation of CO2, causing some carbon loss; however such decarboxylation is slow in the presence of xylose. The catalyst retained comparable activity, in terms of product selectivity, after five cycles with no sign of Pt leaching. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Shotgun Proteomics of Aspergillus niger Microsomes upon d-Xylose Induction▿ †

    Science.gov (United States)

    de Oliveira, José Miguel P. Ferreira; van Passel, Mark W. J.; Schaap, Peter J.; de Graaff, Leo H.

    2010-01-01

    Protein secretion plays an eminent role in cell maintenance and adaptation to the extracellular environment of microorganisms. Although protein secretion is an extremely efficient process in filamentous fungi, the mechanisms underlying protein secretion have remained largely uncharacterized in these organisms. In this study, we analyzed the effects of the d-xylose induction of cellulase and hemicellulase enzyme secretion on the protein composition of secretory organelles in Aspergillus niger. We aimed to systematically identify the components involved in the secretion of these enzymes via mass spectrometry of enriched subcellular microsomal fractions. Under each condition, fractions enriched for secretory organelles were processed for tandem mass spectrometry, resulting in the identification of peptides that originate from 1,081 proteins, 254 of which—many of them hypothetical proteins—were predicted to play direct roles in the secretory pathway. d-Xylose induction led to an increase in specific small GTPases known to be associated with polarized growth, exocytosis, and endocytosis. Moreover, the endoplasmic-reticulum-associated degradation (ERAD) components Cdc48 and all 14 of the 20S proteasomal subunits were recruited to the secretory organelles. In conclusion, induction of extracellular enzymes results in specific changes in the secretory subproteome of A. niger, and the most prominent change found in this study was the recruitment of the 20S proteasomal subunits to the secretory organelles. PMID:20453123

  12. Shotgun proteomics of Aspergillus niger microsomes upon D-xylose induction.

    Science.gov (United States)

    Ferreira de Oliveira, José Miguel P; van Passel, Mark W J; Schaap, Peter J; de Graaff, Leo H

    2010-07-01

    Protein secretion plays an eminent role in cell maintenance and adaptation to the extracellular environment of microorganisms. Although protein secretion is an extremely efficient process in filamentous fungi, the mechanisms underlying protein secretion have remained largely uncharacterized in these organisms. In this study, we analyzed the effects of the d-xylose induction of cellulase and hemicellulase enzyme secretion on the protein composition of secretory organelles in Aspergillus niger. We aimed to systematically identify the components involved in the secretion of these enzymes via mass spectrometry of enriched subcellular microsomal fractions. Under each condition, fractions enriched for secretory organelles were processed for tandem mass spectrometry, resulting in the identification of peptides that originate from 1,081 proteins, 254 of which-many of them hypothetical proteins-were predicted to play direct roles in the secretory pathway. d-Xylose induction led to an increase in specific small GTPases known to be associated with polarized growth, exocytosis, and endocytosis. Moreover, the endoplasmic-reticulum-associated degradation (ERAD) components Cdc48 and all 14 of the 20S proteasomal subunits were recruited to the secretory organelles. In conclusion, induction of extracellular enzymes results in specific changes in the secretory subproteome of A. niger, and the most prominent change found in this study was the recruitment of the 20S proteasomal subunits to the secretory organelles.

  13. Quantitative investigations of xylose and arabinose substituents in hydroxypropylated and hydroxyvinylethylated arabinoxylans.

    Science.gov (United States)

    Lorenz, Dominic; Knöpfle, Anna; Akil, Youssef; Saake, Bodo

    2017-11-01

    The chemical structures obtained by the modification of arabinoxylans with the cyclic carbonates propylene carbonate (PC) and 4-vinyl-1,3-dioxolan-2-one (VEC) with varying degrees of substitution were investigated. Therefore, a new analytical method was developed that is based on a microwave-assisted hydrolysis of the polysaccharides with trifluoroacetic acid and the reductive amination with 2-aminobenzoic acid. The peak assignment was achieved by HPLC-MS and the carbohydrate derivatives were quantified by HPLC-fluorescence. The obtained maximum molar substitution of PC-derivatized xylan (X HP ) was 1.8; the molar substitution of VEC-derivatized xylan (X HVE ) was 2.3. Investigations of xylose and arabinose based mono- and disubstituted derivatives revealed a preferred reaction of the cyclic carbonates with arabinose. Conversion rates were up to 2.4 times higher for monosubstitution and up to 3.0 times for disubstitution compared to xylose. Furthermore, the reaction with VEC was preferred due to higher reactivity of the newly introduced side chains. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. [Emerging pathogen: Candida kefyr (Kluvyeromyces marxianus)].

    Science.gov (United States)

    Çuhadar, Tuğba; Kalkancı, Ayşe

    2017-10-01

    In the central microbiology laboratory of Gazi University Hospital Candida kefyr was isolated from different clinical samples as 5.3% in 2016 and in 2017 this rate increased to 9.3% which was nearly two-fold and this has drawn our attention. The aim of this study was to evaluate the special characteristics, antifungal susceptibility and virulence properties of C.keyfr species. Germ tube, corn meal-tween 80 agar morphology and carbohydrate assimilation profiles on ID32C yeast identification system were used for the diagnosis of Candida species. In this study, DNA sequencing was performed using ITS1 and ITS4 primers amplifying fungal gene between 5.8S and 18S regions of rRNA. Antifungal susceptibility was performed using M27A microdilution method recommended by Clinical and Laboratory Standards Institute (CLSI). Minimum inhibitory concentration (MIC) values for amphotericin B, fluconazole, voriconazole and itraconazole were determined. MIC distribution, MIC50 and MIC90 values and geometric mean (GM) were detected. The existence of virulence factors caseinase, secreted aspartyl proteinase, esterase and phospholipase were investigated in vitro. A total of 865 Candida species were isolated from different clinical samples in the central microbiology laboratory of Gazi University Hospital in 2016. Among them, 46 (5.3%) were C.kefyr. In the first four months of 2017, 30 (9.3%) C.kefyr were identified among 320 Candida isolates. Ten isolates which have shown atypical morphology on corn meal agar were selected. Among these 10 isolates, nine of them were identified as C.kefyr by using ID32C system and DNA sequencing method. Amphotericin B MIC value was 2 µg/ml for one isolate, and fluconazole MIC value was 8 µg/ml for another isolate among 46 isolates. Among the 30 isolates of the year 2017, one of them presented MIC value for fluconazole as 8 µg/ml. No marked antifungal resistance was detected in our isolate group. Caseinase was positive in one C.kefyr isolate, and

  15. Influence of probiotics on Candida presence and IgA anti-Candida in the oral cavity

    Directory of Open Access Journals (Sweden)

    Agda Lima dos Santos

    2009-12-01

    Full Text Available Probiotics are defined as microorganisms that promote benefits to host health, mainly by regulating resident microbiota. Disequilibrium in microbiota can favor the growth of opportunist microorganisms and the development of pathologies, like candidosis caused by yeasts of the Candida genus. This work evaluated whether probiotics consumption was able to influence a specific immunological response to Candida and the presence of these yeasts in the oral cavity. Saliva samples were collected from healthy individuals and plated in Dextrose Saboraud Agar with chloramphenicol. Individuals presenting Candida in the oral cavity used the probiotic Yakult LBâ for 20 days, after which new collections and identifications were performed. Anti-Candida IgA analysis was conducted using the ELISA technique. Analysis of the results showed a significant reduction in Candida prevalence (46% and mean Candida CFU/mL counts (65%. The Candida species identified were C. albicans (98% and C.tropicalis (2%, before and after probiotics consumption. Immunological analysis demonstrated a significant reduction in anti-Candida IgA levels after probiotics use, probably due to less antigenic stimulation. In conclusion, in the individuals studied, probiotics use significantly reduced the amount of Candida in the oral cavity, possibly due to competition between the yeasts rather than by specific secretory immune response stimulation.

  16. Use of CHROMagar Candida for the presumptive identification of Candida species directly from clinical specimens in resource-limited settings

    Science.gov (United States)

    Nadeem, Sayyada Ghufrana; Hakim, Shazia Tabassum; Kazmi, Shahana Urooj

    2010-01-01

    Introduction Identification of yeast isolated from clinical specimens to the species level has become increasingly important. Ever-increasing numbers of immuno-suppressed patients, a widening range of recognized pathogens, and the discovery of resistance to antifungal drugs are contributing factors to this necessity. Material and methods A total of 487 yeast strains were studied for the primary isolation and presumptive identification, directly from clinical specimen. Efficacy of CHROMagar Candida has been evaluated with conventional methods including morphology on Corn meal–tween 80 agar and biochemical methods by using API 20 C AUX. Results The result of this study shows that CHROMagar Candida can easily identify three species of Candida on the basis of colonial color and morphology, and accurately differentiate between them i.e. Candida albicans, Candida tropicalis, and Candida krusei. The specificity and sensitivity of CHROMagar Candida for C. albicans calculated as 99%, for C. tropicalis calculated as 98%, and C. krusei it is 100%. Conclusion The data presented supports the use of CHROMagar Candida for the rapid identification of Candida species directly from clinical specimens in resource-limited settings, which could be very helpful in developing appropriate therapeutic strategy and management of patients. PMID:21483597

  17. Use of CHROMagar Candida for the presumptive identification of Candida species directly from clinical specimens in resource-limited settings

    Directory of Open Access Journals (Sweden)

    Sayyada Ghufrana Nadeem

    2010-02-01

    Full Text Available Introduction: Identification of yeast isolated from clinical specimens to the species level has become increasingly important. Ever-increasing numbers of immuno-suppressed patients, a widening range of recognized pathogens, and the discovery of resistance to antifungal drugs are contributing factors to this necessity. Material and methods: A total of 487 yeast strains were studied for the primary isolation and presumptive identification, directly from clinical specimen. Efficacy of CHROMagar Candida has been evaluated with conventional methods including morphology on Corn meal–tween 80 agar and biochemical methods by using API 20 C AUX. Results: The result of this study shows that CHROMagar Candida can easily identify three species of Candida on the basis of colonial color and morphology, and accurately differentiate between them i.e. Candida albicans, Candida tropicalis, and Candida krusei. The specificity and sensitivity of CHROMagar Candida for C. albicans calculated as 99%, for C. tropicalis calculated as 98%, and C. krusei it is 100%. Conclusion: The data presented supports the use of CHROMagar Candida for the rapid identification of Candida species directly from clinical specimens in resource-limited settings, which could be very helpful in developing appropriate therapeutic strategy and management of patients.

  18. Use of CHROMagar Candida for the presumptive identification of Candida species directly from clinical specimens in resource-limited settings.

    Science.gov (United States)

    Nadeem, Sayyada Ghufrana; Hakim, Shazia Tabassum; Kazmi, Shahana Urooj

    2010-02-09

    Identification of yeast isolated from clinical specimens to the species level has become increasingly important. Ever-increasing numbers of immuno-suppressed patients, a widening range of recognized pathogens, and the discovery of resistance to antifungal drugs are contributing factors to this necessity. A total of 487 yeast strains were studied for the primary isolation and presumptive identification, directly from clinical specimen. Efficacy of CHROMagar Candida has been evaluated with conventional methods including morphology on Corn meal-tween 80 agar and biochemical methods by using API 20 C AUX. The result of this study shows that CHROMagar Candida can easily identify three species of Candida on the basis of colonial color and morphology, and accurately differentiate between them i.e. Candida albicans, Candida tropicalis, and Candida krusei. The specificity and sensitivity of CHROMagar Candida for C. albicans calculated as 99%, for C. tropicalis calculated as 98%, and C. krusei it is 100%. The data presented supports the use of CHROMagar Candida for the rapid identification of Candida species directly from clinical specimens in resource-limited settings, which could be very helpful in developing appropriate therapeutic strategy and management of patients.

  19. Small intestinal malabsorption in chronic alcoholism: a retrospective study of alcoholic patients by the ¹⁴C-D-xylose breath test.

    Science.gov (United States)

    Hope, Håvar; Skar, Viggo; Sandstad, Olav; Husebye, Einar; Medhus, Asle W

    2012-04-01

    The ¹⁴C-D-xylose breath test was used at Ullevål University Hospital in the period from 1986 TO 1995 for malabsorption testing. The objective of this retrospective study was to reveal whether patients with chronic alcoholism may have intestinal malabsorption. The consecutive ¹⁴C-D-xylose breath test database was reviewed and patients with the diagnosis of chronic alcoholism were identified. ¹⁴C-D-xylose breath test results of the alcoholic patients were compared with the results of untreated celiac patients and patient and healthy controls. In the ¹⁴C-D-xylose breath test, ¹⁴C-D-xylose was dissolved in water and given orally after overnight fast. Breath samples were taken at 30-min intervals for 210 min, and ¹⁴CO₂ : ¹²CO₂ ratios were calculated for each time point, presenting a time curve for ¹⁴C-D-xylose absorption. Urine was collected after 210 min and the fraction of the total d-xylose passed was calculated (U%). ¹⁴CO₂ in breath and ¹⁴C-D-xylose in urine were analyzed using liquid scintillation. Both breath and urine analysis revealed a pattern of malabsorption in alcoholics comparable with untreated celiac patients, with significantly reduced absorption of d-xylose compared with patient and healthy controls. Alcoholic patients have a significantly reduced ¹⁴C-D-xylose absorption, comparable with untreated celiac patients. This indicates a reduced intestinal function in chronic alcoholism.

  20. Direct production of D-arabinose from D-xylose by a coupling reaction using D-xylose isomerase, D-tagatose 3-epimerase and D-arabinose isomerase.

    Science.gov (United States)

    Sultana, Ishrat; Mizanur, Rahman Md; Takeshita, Kei; Takada, Goro; Izumori, Ken

    2003-01-01

    Klebsiella pneumoniae 40bXX, a mutant strain that constitutively produces D-arabinose isomerase (D-AI), was isolated through a series of repeated subcultures from the parent strain on a mineral salt medium supplemented with L-Xylose as the sole carbon source. D-AI could be efficiently immobilized on chitopearl beads. The optimum temperature for the activity of the immobilized enzyme was 40 degrees C and the enzyme was stable up to 50 degrees C. The D-Al was active at pH 10.0 and was stable in the range of pH 6.0-11.0. The enzyme required manganese ions for maximum activity. Three immobilized enzymes, D-xylose isomerase (D-XI), D-tagatose 3-epimerase (D-TE and D-AI were used for the preparation of D-arabinose from D-xylose in a coupling reaction. After completion of the reaction, degradation of D-xylulose was carried out by Saccharomyces cerevisiae. The reaction mixture containing D-Xylose, D-ribulose and the product was then separated by ion exchange column chromatography. After crystallization, the product was checked by HPLC, IR spectroscopy, NMR spectroscopy and optical rotation measurements. Finally, 2.0 g of D-arabinose could be obtained from 5 g of the substrate.

  1. Scale‐up and intensification of (S)‐1‐(2‐chlorophenyl)ethanol bioproduction: Economic evaluation of whole cell‐catalyzed reduction of o‐Chloroacetophenone

    DEFF Research Database (Denmark)

    Eixelsberger, Thomas; Woodley, John; Nidetzky, Bernd

    2013-01-01

    Escherichia coli cells co‐expressing genes coding for Candida tenuis xylose reductase and Candida boidinii formate dehydrogenase were used for the bioreduction of o‐chloroacetophenone with in situ coenzyme recycling. The product, (S)‐1‐(2‐chlorophenyl)ethanol, is a key chiral intermediate...... in the synthesis of polo‐like kinase 1 inhibitors, a new class of chemotherapeutic drugs. Production of the alcohol in multi‐gram scale requires intensification and scale‐up of the biocatalyst production, biotransformation, and downstream processing. Cell cultivation in a 6.9‐L bioreactor led to a more than...... costs by 80% and enabled (S)‐1‐(2‐chlorophenyl)ethanol production within previously defined economic boundaries. A simple and efficient way to synthesize (S)‐1‐(2‐chlorophenyl)ethanol in an isolated amount of 20 g product per reaction batch was demonstrated. Biotechnol. Bioeng. 2013; 110: 2311...

  2. Aislamiento de Candida dubliniensis en distintos materiales clínicos: Análisis de métodos fenotípicos de diferenciación con Candida albicans Isolation of Candida dubliniensis in different clinical samples: Analysis of phenotypical methods to differenciate from Candida albicans

    Directory of Open Access Journals (Sweden)

    G. Pineda

    2008-12-01

    CHROMagar® Candida medium and produced germ tubes and chlamidoconidiae in milk-agar; so as to distinguish whether they corresponded to Candida albicans or C. dubliniensis, different phenotypical methods were utilized. It was also evaluated the usefulness of each one in order to suggest a simple, economic and reliable identification algorithm. Each isolate was subcultured in two chromogenic media and then, the following determinations were done: chlamidospores production in Staib-agar, tomato-carrot-agar and tobacco-agar, colonies macromorphology was also studied in the last medium; opacity-test in Tween 80-CaCl2 agar (lipase activity, growing capacity at 45 °C, and D-xylose assimilation. Thirteen strains (6.1% corresponded to C. dubliniensis. The difference in color between both species on chromogenic media was not so stressed as it is pointed out in some works. The more specific and sensitive tests were the ability to grow at 45 °C, D-xylose assimilation, color and macroscopic appearance in tobacco-agar. Between 11.6% and 15.1% of C. albicans strains produced chlamidoconidiae in the 3 differential media tested. The opacity halo (lipase was evident in 95.6% of C. albicans isolates but 2 out of 13 C. dubliniensis also presented precipitation halo. We consider that at least 3 different phenotypical methods should be used to distinguish properly these two species since none of the tests is absolutely sensitive or specific.

  3. Metabolic responses in Candida tropicalis to complex inhibitors during xylitol bioconversion.

    Science.gov (United States)

    Wang, Shizeng; Li, Hao; Fan, Xiaoguang; Zhang, Jingkun; Tang, Pingwah; Yuan, Qipeng

    2015-09-01

    During xylitol fermentation, Candida tropicalis is often inhibited by inhibitors in hemicellulose hydrolysate. The mechanisms involved in the metabolic responses to inhibitor stress and the resistances to inhibitors are still not clear. To understand the inhibition mechanisms and the metabolic responses to inhibitors, a GC/MS-based metabolomics approach was performed on C. tropicalis treated with and without complex inhibitors (CI, including furfural, phenol and acetic acid). Partial least squares discriminant analysis was used to determine the metabolic variability between CI-treated groups and control groups, and 25 metabolites were identified as possible entities responsible for the discrimination caused by inhibitors. We found that xylose uptake rate and xylitol oxidation rate were promoted by CI treatment. Metabolomics analysis showed that the flux from xylulose to pentose phosphate pathway increased, and tricarboxylic acid cycle was disturbed by CI. Moreover, the changes in levels of 1,3-propanediol, trehalose, saturated fatty acids and amino acids showed different mechanisms involved in metabolic responses to inhibitor stress. The increase of 1,3-propanediol was considered to be correlated with regulating redox balance and osmoregulation. The increase of trehalose might play a role in protein stabilization and cellular membranes protection. Saturated fatty acids could cause the decrease of membrane fluidity and make the plasma membrane rigid to maintain the integrity of plasma membrane. The deeper understanding of the inhibition mechanisms and the metabolic responses to inhibitors will provide us with more information on the metabolism regulation during xylitol bioconversion and the construction of industrial strains with inhibitor tolerance for better utilization of bioresource. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Culture media profoundly affect Candida albicans and Candida tropicalis growth, adhesion and biofilm development.

    Science.gov (United States)

    Weerasekera, Manjula M; Wijesinghe, Gayan K; Jayarathna, Thilini A; Gunasekara, Chinthika P; Fernando, Neluka; Kottegoda, Nilwala; Samaranayake, Lakshman P

    2016-11-01

    As there are sparse data on the impact of growth media on the phenomenon of biofilm development for Candida we evaluated the efficacy of three culture media on growth, adhesion and biofilm formation of two pathogenic yeasts, Candida albicans and Candida tropicalis. The planktonic phase yeast growth, either as monocultures or mixed cultures, in sabouraud dextrose broth (SDB), yeast nitrogen base (YNB), and RPMI 1640 was compared, and adhesion as well as biofilm formation were monitored using MTT and crystal violet (CV) assays and scanning electron microscopy. Planktonic cells of C. albicans, C. tropicalis and their 1:1 co-culture showed maximal growth in SDB. C. albicans/C. tropicalis adhesion was significantly facilitated in RPMI 1640 although the YNB elicited the maximum growth for C. tropicalis. Similarly, the biofilm growth was uniformly higher for both species in RPMI 1640, and C. tropicalis was the slower biofilm former in all three media. Scanning electron microscopy images tended to confirm the results of MTT and CV assay. Taken together, our data indicate that researchers should pay heed to the choice of laboratory culture media when comparing relative planktonic/biofilm growth of Candida. There is also a need for standardisation of biofilm development media so as to facilitate cross comparisons between laboratories.

  5. prevalence and antifungal susceptibility of candida species isolated

    African Journals Online (AJOL)

    User

    Candida species isolated from HVS specimens were Candida albicans (n=19, 48.7%), Can- dida glabrata .... C test kits. The isolates were stored ... problem that causes significant morbidity and affects the .... from both urinary and high vaginal specimens followed by ... drugs that are used in the treatment of infec- tions due ...

  6. Incidence and Speciation of Candida Species among Non-gravid ...

    African Journals Online (AJOL)

    This study investigated the incidence and speciation of Candida species among non-gravid young females, using commercially available chromogenic Candida speciation media (CHROM agar) for the identification/speciation of medically important yeast and yeastlike organisms in a routine clinical mycology laboratory.

  7. Quantification and Correlation of Oral Candida with Caries Index ...

    African Journals Online (AJOL)

    Background: Dental caries is the most common infectious disease affecting humans and is the predominant cause of tooth loss in children. Although Candida's role in dental caries has been studied extensively, limited homogenous studies have been conducted and none have been found, that associate Candida with ...

  8. Hexosomes with Undecylenic Acid Efficient against Candida albicans.

    Science.gov (United States)

    Mionić Ebersold, Marijana; Petrović, Milica; Fong, Wye-Khay; Bonvin, Debora; Hofmann, Heinrich; Milošević, Irena

    2018-02-07

    Due to the growing issues with fungal infections, especially with Candida , there is still a need to develop novel anti- Candida materials. One of the known antifungal agents is undecylenic acid (UA), which still cannot be efficiently used due to its oily nature, and thus limited solubility. By taking advantage of the properties of UA, we developed an emulsion with hexagonal phase, i.e., hexosomes, whose structure and morphology was studied by small-angle X-ray scattering and cryo-electron microscopy, respectively. The presence of UA in the hexosome was confirmed by spectroscopy. Moreover, we studied the anti- Candida effect of hexosomes and their cytotoxicity toward human cells. The minimal inhibitory concentration for the 50% and 90% Candida -growth reduction was found at 0.01 and 0.16 wt % hexosomes, respectively (i.e., 2 and 32 pg hex / C.a. cell, respectively). The percentage of metabolically active Candida was reduced by 72-96% at hexosome concentrations of 1.0-8.2 pg hex / C.a. cell as compared to untreated Candida . Furthermore, at the same concentration range the embedded filamentation test after 24 and 48 h showed the inhibition of both the filamentation and growth of Candida , while the preliminary toxicity test showed that hexosomes were nontoxic for human cells. All these render the here-developed hexosomes with UA efficient and promising anti- Candida agents.

  9. Hexosomes with Undecylenic Acid Efficient against Candida albicans

    Directory of Open Access Journals (Sweden)

    Marijana Mionić Ebersold

    2018-02-01

    Full Text Available Due to the growing issues with fungal infections, especially with Candida, there is still a need to develop novel anti-Candida materials. One of the known antifungal agents is undecylenic acid (UA, which still cannot be efficiently used due to its oily nature, and thus limited solubility. By taking advantage of the properties of UA, we developed an emulsion with hexagonal phase, i.e., hexosomes, whose structure and morphology was studied by small-angle X-ray scattering and cryo-electron microscopy, respectively. The presence of UA in the hexosome was confirmed by spectroscopy. Moreover, we studied the anti-Candida effect of hexosomes and their cytotoxicity toward human cells. The minimal inhibitory concentration for the 50% and 90% Candida-growth reduction was found at 0.01 and 0.16 wt % hexosomes, respectively (i.e., 2 and 32 pghex/C.a.cell, respectively. The percentage of metabolically active Candida was reduced by 72–96% at hexosome concentrations of 1.0–8.2 pghex/C.a.cell as compared to untreated Candida. Furthermore, at the same concentration range the embedded filamentation test after 24 and 48 h showed the inhibition of both the filamentation and growth of Candida, while the preliminary toxicity test showed that hexosomes were nontoxic for human cells. All these render the here-developed hexosomes with UA efficient and promising anti-Candida agents.

  10. Multigeneration toxicity of imidacloprid and thiacloprid to Folsomia candida

    NARCIS (Netherlands)

    van Gestel, Cornelis A.M.; de Lima e Silva, Claudia; Lam, Thao; Koekkoek, Jacco C.; Lamoree, Marja H.; Verweij, Rudo A.

    2017-01-01

    In a recent study, we showed that the springtail Folsomia candida was quite sensitive the neonicotinoid insecticides imidacloprid and thiacloprid. This study aimed at determining the toxicity of both compounds to F. candida following exposure over three generations, in natural LUFA 2.2 standard

  11. Plants’ Natural Products as Alternative Promising Anti-Candida Drugs

    Science.gov (United States)

    Soliman, Sameh; Alnajdy, Dina; El-Keblawy, Ali A.; Mosa, Kareem A.; Khoder, Ghalia; Noreddin, Ayman M.

    2017-01-01

    Candida is a serious life-threatening pathogen, particularly with immunocompromised patients. Candida infections are considered as a major cause of morbidity and mortality in a broad range of immunocompromised patients. Candida infections are common in hospitalized patients and elderly people. The difficulty to eradicate Candida infections is owing to its unique switch between yeast and hyphae forms and more likely to biofilm formations that render resistance to antifungal therapy. Plants are known sources of natural medicines. Several plants show significant anti-Candida activities and some of them have lower minimum inhibitory concentration, making them promising candidates for anti-Candida therapy. However, none of these plant products is marketed for anti-Candida therapy because of lack of sufficient information about their efficacy, toxicity, and kinetics. This review revises major plants that have been tested for anti-Candida activities with recommendations for further use of some of these plants for more investigation and in vivo testing including the use of nanostructure lipid system. PMID:28989245

  12. Candida Arthritis: Analysis of 112 Pediatric and Adult Cases

    Science.gov (United States)

    Gamaletsou, Maria N.; Rammaert, Blandine; Bueno, Marimelle A.; Sipsas, Nikolaos V.; Moriyama, Brad; Kontoyiannis, Dimitrios P.; Roilides, Emmanuel; Zeller, Valerie; Taj-Aldeen, Saad J.; Miller, Andy O.; Petraitiene, Ruta; Lortholary, Olivier; Walsh, Thomas J.

    2016-01-01

    Background. Candida arthritis is a debilitating form of deeply invasive candidiasis. However, its epidemiology, clinical manifestations, management, and outcome are not well understood. Methods. Cases of Candida arthritis were reviewed from 1967 through 2014. Variables included Candida spp in joint and/or adjacent bone, underlying conditions, clinical manifestations, inflammatory biomarkers, diagnostic imaging, management, and outcome. Results. Among 112 evaluable cases, 62% were males and 36% were pediatric. Median age was 40 years (range, Candida albicans constituted 63%, Candida tropicalis 14%, and Candida parapsilosis 11%. Most cases (66%) arose de novo, whereas 34% emerged during antifungal therapy. Osteolysis occurred in 42%, joint-effusion in 31%, and soft tissue extension in 21%. Amphotericin and fluconazole were the most commonly used agents. Surgical interventions included debridement in 25%, irrigation 10%, and drainage 12%. Complete or partial response was achieved in 96% and relapse in 16%. Conclusion. Candida arthritis mainly emerges as a de novo infection in usually non-immunosuppressed patients with hips and knees being most commonly infected. Localizing symptoms are frequent, and the most common etiologic agents are C albicans, C tropicalis, and C parapsilosis. Management of Candida arthritis remains challenging with a clear risk of relapse, despite antifungal therapy. PMID:26858961

  13. Speciation of Candida isolates obtained from diarrheal stool

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    Beena Uppal

    2016-01-01

    Conclusion Candida diarrhea was mostly seen in individuals younger than 12 years, most commonly caused by C. krusei. Resistance to fluconazole was high. A rising resistance to amphotericin B is alarming. Speciation of Candida is important to see the difference in antifungal susceptibility in different species.

  14. Emerging azole resistance among Candida albicans from clinical ...

    African Journals Online (AJOL)

    Candida albicans is one of the most frequently isolated yeasts in clinical laboratories and accounts for up to 80 % of the yeasts recovered from sites of infection. The study was set out to determine antifungal susceptibility of clinical isolates of Candida albicans and to establish the Minimum Inhibitory Concentrations (MIC) to ...

  15. Expression of mtc in Folsomia candida indicative of metal pollution.

    NARCIS (Netherlands)

    Nota, B.; Vooijs, H.; van Straalen, N.M.; Roelofs, D.

    2011-01-01

    The soil-living springtail Folsomia candida is frequently used in reproduction bioassays to assess soil contamination. Alternatively, the response of genes to contamination is assessed. In this study the expression of F. candida's gene encoding the deduced metallothionein-like motif containing

  16. Oral candida infection among HIV patients at Kilimanjaro Christian ...

    African Journals Online (AJOL)

    candida infection in HIV positive patients and investigate the relationship between oral manifestations ... and prescription at Child Centred Family Care Clinic at KCMC for a period of 12 months. .... et al., 2013) compared candida colonization in asymptomatic HIV patients and control. .... Journal of Dental Research, Dental.

  17. Microbial production of xylitol from xylose and L-arabinose: conversion of L-arabitol to xylitol using bacterial oxidoreductases

    Science.gov (United States)

    Microbial production of xylitol, using hemicellulosic biomass such as agricultural residues, is becoming more attractive for reducing its manufacturing cost. L-arabitol is a particular problem to xylitol production from hemicellulosic hydrolyzates that contain both xylose and L-arabinose because it...

  18. One-pot conversion of biomass-derived xylose and furfural into levulinate esters via acid catalysis.

    Science.gov (United States)

    Hu, Xun; Jiang, Shengjuan; Wu, Liping; Wang, Shuai; Li, Chun-Zhu

    2017-03-07

    Direct conversion of biomass-derived xylose and furfural into levulinic acid, a platform molecule, via acid-catalysis has been accomplished for the first time in dimethoxymethane/methanol. Dimethoxymethane acted as an electrophile to transform furfural into 5-hydroxymethylfurfural (HMF). Methanol suppressed both the polymerisation of the sugars/furans and the Aldol condensation of levulinic acid/ester.

  19. Optimised formation of blue Maillard reaction products of xylose and glycine model systems and associated antioxidant activity.

    Science.gov (United States)

    Yin, Zi; Sun, Qian; Zhang, Xi; Jing, Hao

    2014-05-01

    A blue colour can be formed in the xylose (Xyl) and glycine (Gly) Maillard reaction (MR) model system. However, there are fewer studies on the reaction conditions for the blue Maillard reaction products (MRPs). The objective of this study is to investigate characteristic colour formation and antioxidant activities in four different MR model systems and to determine the optimum reaction conditions for the blue colour formation in a Xyl-Gly MR model system, using the random centroid optimisation program. The blue colour with an absorbance peak at 630 nm appeared before browning in the Xyl-Gly MR model system, while no blue colour formation but only browning was observed in the xylose-alanine, xylose-aspartic acid and glucose-glycine MR model systems. The Xyl-Gly MR model system also showed higher antioxidant activity than the other three model systems. The optimum conditions for blue colour formation were as follows: xylose and glycine ratio 1:0.16 (M:M), 0.20 mol L⁻¹ NaHCO₃, 406.1 mL L⁻¹ ethanol, initial pH 8.63, 33.7°C for 22.06 h, which gave a much brighter blue colour and a higher peak at 630 nm. A characteristic blue colour could be formed in the Xyl-Gly MR model system and the optimum conditions for the blue colour formation were proposed and confirmed. © 2013 Society of Chemical Industry.

  20. Oral candidiasis-adhesion of non-albicans Candida species

    Directory of Open Access Journals (Sweden)

    Bokor-Bratić Marija B.

    2008-01-01

    Full Text Available Oral candidiasis is an opportunistic infection caused primarily by Candida albicans. However, in recent years, species of non-albicans Candida have been implicated more frequently in mucosal infection. Candida species usually reside as commensal organisms and are part of normal oral microflora. Determining exactly how transformation from commensal to pathogen takes place and how it can be prevented is continuous challenge for clinical doctors. Candidal adherence to mucosal surfaces is considered as a critical initial step in the pathogenesis of oral candidiasis. Acrylic dentures, acting as reservoirs, play an important role in increasing the risk from Candida colonisation. Thus, this review discusses what is currently known about the adhesion of non-albicans Candida species of oral origin to buccal epithelial cells and denture acrylics.

  1. Candida glabrata olecranon bursitis treated with bursectomy and intravenous caspofungin.

    Science.gov (United States)

    Skedros, John G; Keenan, Kendra E; Trachtenberg, Joel D

    2013-01-01

    Orthopedic surgeons are becoming more involved in the care of patients with septic arthritis and bursitis caused by yeast species. This case report involves a middle-aged immunocompromised female who developed a Candida glabrata septic olecranon bursitis that developed after she received a corticosteroid injection in the olecranon bursa for presumed aseptic bursitis. Candida (Torulopsis) glabrata is the second most frequently isolated Candida species from the bloodstream in the United States. Increased use of fluconazole and other azole antifungal agents as a prophylactic treatment for recurrent Candida albicans infections in immunocompromised individuals is one reason why there appears to be increased resistance of C. glabrata and other nonalbicans Candida (NAC) species to fluconazole. In this patient, this infection was treated with surgery (bursectomy) and intravenous caspofungin, an echinocandin. This rare infectious etiology coupled with this intravenous antifungal treatment makes this case novel among cases of olecranon bursitis caused by yeasts.

  2. Risk factors for fatal candidemia caused by Candida albicans and non-albicans Candida species

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    Tang Ran-Bin

    2005-04-01

    Full Text Available Abstract Background Invasive fungal infections, such as candidemia, caused by Candida species have been increasing. Candidemia is not only associated with a high mortality (30% to 40% but also extends the length of hospital stay and increases the costs of medical care. Sepsis caused by Candida species is clinically indistinguishable from bacterial infections. Although, the clinical presentations of the patients with candidemia caused by Candida albicans and non-albicans Candida species (NAC are indistinguishable, the susceptibilities to antifungal agents of these species are different. In this study, we attempted to identify the risk factors for candidemia caused by C. albicans and NAC in the hope that this may guide initial empiric therapy. Methods A retrospective chart review was conducted during 1996 to 1999 at the Veterans General Hospital-Taipei. Results There were 130 fatal cases of candidemia, including 68 patients with C. albicans and 62 with NAC. Candidemia was the most likely cause of death in 55 of the 130 patients (42.3 %. There was no significant difference in the distribution of Candida species between those died of candidemia and those died of underlying conditions. Patients who had one of the following conditions were more likely to have C. albicans, age ≧ 65 years, immunosuppression accounted to prior use of steroids, leukocytosis, in the intensive care unit (ICU, and intravascular and urinary catheters. Patients who had undergone cancer chemotherapy often appeared less critically ill and were more likely to have NAC. Conclusion Clinical and epidemiological differences in the risk factors between candidemia caused by C. albicans and NAC may provide helpful clues to initiate empiric therapy for patients infected with C. albicans versus NAC.

  3. Risk factors for fatal candidemia caused by Candida albicans and non-albicans Candida species

    Science.gov (United States)

    Cheng, Ming-Fang; Yang, Yun-Liang; Yao, Tzy-Jyun; Lin, Chin-Yu; Liu, Jih-Shin; Tang, Ran-Bin; Yu, Kwok-Woon; Fan, Yu-Hua; Hsieh, Kai-Sheng; Ho, Monto; Lo, Hsiu-Jung

    2005-01-01

    Background Invasive fungal infections, such as candidemia, caused by Candida species have been increasing. Candidemia is not only associated with a high mortality (30% to 40%) but also extends the length of hospital stay and increases the costs of medical care. Sepsis caused by Candida species is clinically indistinguishable from bacterial infections. Although, the clinical presentations of the patients with candidemia caused by Candida albicans and non-albicans Candida species (NAC) are indistinguishable, the susceptibilities to antifungal agents of these species are different. In this study, we attempted to identify the risk factors for candidemia caused by C. albicans and NAC in the hope that this may guide initial empiric therapy. Methods A retrospective chart review was conducted during 1996 to 1999 at the Veterans General Hospital-Taipei. Results There were 130 fatal cases of candidemia, including 68 patients with C. albicans and 62 with NAC. Candidemia was the most likely cause of death in 55 of the 130 patients (42.3 %). There was no significant difference in the distribution of Candida species between those died of candidemia and those died of underlying conditions. Patients who had one of the following conditions were more likely to have C. albicans, age ≧ 65 years, immunosuppression accounted to prior use of steroids, leukocytosis, in the intensive care unit (ICU), and intravascular and urinary catheters. Patients who had undergone cancer chemotherapy often appeared less critically ill and were more likely to have NAC. Conclusion Clinical and epidemiological differences in the risk factors between candidemia caused by C. albicans and NAC may provide helpful clues to initiate empiric therapy for patients infected with C. albicans versus NAC. PMID:15813977

  4. Protein enrichment of an Opuntia ficus-indica cladode hydrolysate by cultivation of Candida utilis and Kluyveromyces marxianus.

    Science.gov (United States)

    Akanni, Gabriel B; du Preez, James C; Steyn, Laurinda; Kilian, Stephanus G

    2015-03-30

    The cladodes of Opuntia ficus-indica (prickly pear cactus) have a low protein content; for use as a balanced feed, supplementation with other protein sources is therefore desirable. We investigated protein enrichment by cultivation of the yeasts Candida utilis and Kluyveromyces marxianus in an enzymatic hydrolysate of the cladode biomass. Dilute acid pretreatment and enzymatic hydrolysis of sun-dried cladodes resulted in a hydrolysate containing (per litre) 45.5 g glucose, 6.3 g xylose, 9.1 g galactose, 10.8 g arabinose and 9.6 g fructose. Even though K. marxianus had a much higher growth rate and utilized l-arabinose and d-galactose more completely than C. utilis, its biomass yield coefficient was lower due to ethanol and ethyl acetate production despite aerobic cultivation. Yeast cultivation more than doubled the protein content of the hydrolysate, with an essential amino acid profile superior to sorghum and millet grains. This K. marxianus strain was weakly Crabtree positive. Despite its low biomass yield, its performance compared well with C. utilis. This is the first report showing that the protein content and quality of O. ficus-indica cladode biomass could substantially be improved by yeast cultivation, including a comparative evaluation of C. utilis and K. marxianus. © 2014 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

  5. Ethanol and xylitol production by fermentation of acid hydrolysate from olive pruning with Candida tropicalis NBRC 0618.

    Science.gov (United States)

    Mateo, Soledad; Puentes, Juan G; Moya, Alberto J; Sánchez, Sebastián

    2015-08-01

    Olive tree pruning biomass has been pretreated with pressurized steam, hydrolysed with hydrochloric acid, conditioned and afterwards fermented using the non-traditional yeast Candida tropicalis NBRC 0618. The main aim of this study was to analyse the influence of acid concentration on the hydrolysis process and its effect on the subsequent fermentation to produce ethanol and xylitol. From the results, it could be deduced that both total sugars and d-glucose recovery were enhanced by increasing the acid concentration tested; almost the whole hemicellulose fraction was hydrolysed when 3.77% was used. It has been observed a sequential production first of ethanol, from d-glucose, and then xylitol from d-xylose. The overall ethanol and xylitol yields ranged from 0.27 to 0.38kgkg(-1), and 0.12 to 0.23kgkg(-1) respectively, reaching the highest values in the fermentation of the hydrolysates obtained with hydrochloric acid 2.61% and 1.11%, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Otite externe maligne à Candida Albicans

    Science.gov (United States)

    Elayoubi, Fahd; Lachkar, Azeddine; Aabach, Ahmed; Chouai, Mohamed; Ghailan, Mohamed Rachid

    2016-01-01

    L’otite externe maligne est une ostéomyélite de la base du crane. Le Pseudomonas aeruginosa est le germe le plus incriminé. Cependant l’origine fongique n’est pas rare. Patiente âgée de 80 ans avait présenté une otalgie gauche persistante depuis deux mois malgré un traitement bien conduit. L’examen otologique mettait en évidence des signes inflammatoires au niveau du pavillon, une sténose du conduit avec des granulomes, et otorrhée d’allure purulente. Le scanner montrait un comblement otomastoïdien, un processus inflammatoire extensif des tissus pré et rétro-auriculaire et une lyse du tympanal. Vu l’absence d’amélioration un examen mycologique a été réalisé et qui a révélé la présence de Candida Albicans. Les cas d’otite externe maligne à Candida Albicans sont rarement rapportés. L’origine fongique doit être suspecté devant la négativité des prélèvements bactériologiques et la non amélioration malgré un traitement antibiotique bien conduit, et confirmée par des prélèvements mycologiques parfois multiples. L’otite externe maligne à Candida Albicans est une infection rare potentiellement mortelle. PMID:28154677

  7. Detecting Candida albicans in human milk.

    Science.gov (United States)

    Morrill, Jimi Francis; Pappagianis, Demosthenes; Heinig, M Jane; Lönnerdal, Bo; Dewey, Kathryn G

    2003-01-01

    Procedures for diagnosis of mammary candidosis, including laboratory confirmation, are not well defined. Lactoferrin present in human milk can inhibit growth of Candida albicans, thereby limiting the ability to detect yeast infections. The inhibitory effect of various lactoferrin concentrations on the growth of C. albicans in whole human milk was studied. The addition of iron to the milk led to a two- to threefold increase in cell counts when milk contained 3.0 mg of lactoferrin/ml and markedly reduced the likelihood of false-negative culture results. This method may provide the necessary objective support needed for diagnosis of mammary candidosis.

  8. Clinical Patterns of Candida Infections in Bombay

    Directory of Open Access Journals (Sweden)

    J Pratiba Dalal

    1980-01-01

    Full Text Available One hundred consecutive cases of candidiasis in Bombay were studied. In each case the suspicion was confirmed by isolation typing of the Candida species. The clinical was as follows: vulvo-vaginitis 30%; intertrigo 18%; onychia and paronychia 12%; thrush 16%; generalised cutaneous candidasis 8%, enteritis 3%; bronchitis 12% and urinary tract infection 1%. When compared to a study carried out in Bombay in 1966, there was an increase in the frequency of disseminated cutaneous candidiasis and a reduction in the cases of intertrigo and onychia and paronychia.

  9. Increased accuracy of the carbon-14 D-xylose breath test in detecting small-intestinal bacterial overgrowth by correction with the gastric emptying rate

    International Nuclear Information System (INIS)

    Chang Chisen; Chen Granhum; Kao Chiahung; Wang Shyhjen; Peng Shihnen; Huang Chihkuen; Poon Sekkwong

    1995-01-01

    The aim of this study was to determine whether the accuracy of 14 C-D-xylose breath test for detecting bacterial overgrowth can be increased by correction with the gastric emptying rate of 14 C-D-xylose. Ten culture-positive patients and ten culture-negative controls were included in the study. Small-intestinal aspirates for bacteriological culture were obtained endoscopically. A liquid-phase gastric emptying study was performed simultaneously to assess the amount of 14 C-D-xylose that entered the small intestine. The results of the percentage of expired 14 CO 2 at 30 min were corrected with the amount of 14 C-D-xylose that entered the small intestine. There were six patients in the culture-positive group with a 14 CO 2 concentration above the normal limit. Three out of four patients with initially negative results using the uncorrected method proved to be positive after correction. All these three patients had prolonged gastric emptying of 14 C-D-xylose. When compared with cultures of small-intestine aspirates, the sensitivity and specificity of the uncorrected 14 C-D-xylose breath test were 60% and 90%, respectively. In contrast, the sensitivity and specificity of the corrected 14 C-D-xylose breath test improved to 90% and 100%, respectively. (orig./MG)

  10. xylA and xylB overexpression as a successful strategy for improving xylose utilization and poly-3-hydroxybutyrate production in Burkholderia sacchari.

    Science.gov (United States)

    Guamán, Linda P; Oliveira-Filho, Edmar R; Barba-Ostria, Carlos; Gomez, José G C; Taciro, Marilda K; da Silva, Luiziana Ferreira

    2018-03-01

    Despite the versatility and many advantages of polyhydroxyalkanoates as petroleum-based plastic substitutes, their higher production cost compared to petroleum-based polymers has historically limited their large-scale production. One appealing approach to reducing production costs is to employ less expensive, renewable feedstocks. Xylose, for example is an abundant and inexpensive carbon source derived from hemicellulosic residues abundant in agro-industrial waste (sugarcane bagasse hemicellulosic hydrolysates). In this work, the production of poly-3-hydroxybutyrate P(3HB) from xylose was studied to develop technologies for conversion of agro-industrial waste into high-value chemicals and biopolymers. Specifically, this work elucidates the organization of the xylose assimilation operon of Burkholderia sacchari, a non-model bacterium with high capacity for P(3HB) accumulation. Overexpression of endogenous xylose isomerase and xylulokinase genes was successfully assessed, improving both specific growth rate and P(3HB) production. Compared to control strain (harboring pBBR1MCS-2), xylose utilization in the engineered strain was substantially improved with 25% increase in specific growth rate, 34% increase in P(3HB) production, and the highest P(3HB) yield from xylose reported to date for B. sacchari (Y P3HB/Xil  = 0.35 g/g). This study highlights that xylA and xylB overexpression is an effective strategy to improve xylose utilization and P(3HB) production in B. sacchari.

  11. Optimization of CDT-1 and XYL1 Expression for Balanced Co-Production of Ethanol and Xylitol from Cellobiose and Xylose by Engineered Saccharomyces cerevisiae

    Science.gov (United States)

    Zha, Jian; Li, Bing-Zhi; Shen, Ming-Hua; Hu, Meng-Long; Song, Hao; Yuan, Ying-Jin

    2013-01-01

    Production of ethanol and xylitol from lignocellulosic hydrolysates is an alternative to the traditional production of ethanol in utilizing biomass. However, the conversion efficiency of xylose to xylitol is restricted by glucose repression, causing a low xylitol titer. To this end, we cloned genes CDT-1 (encoding a cellodextrin transporter) and gh1-1 (encoding an intracellular β-glucosidase) from Neurospora crassa and XYL1 (encoding a xylose reductase that converts xylose into xylitol) from Scheffersomyces stipitis into Saccharomyces cerevisiae, enabling simultaneous production of ethanol and xylitol from a mixture of cellobiose and xylose (main components of lignocellulosic hydrolysates). We further optimized the expression levels of CDT-1 and XYL1 by manipulating their promoters and copy-numbers, and constructed an engineered S. cerevisiae strain (carrying one copy of PGK1p-CDT1 and two copies of TDH3p-XYL1), which showed an 85.7% increase in xylitol production from the mixture of cellobiose and xylose than that from the mixture of glucose and xylose. Thus, we achieved a balanced co-fermentation of cellobiose (0.165 g/L/h) and xylose (0.162 g/L/h) at similar rates to co-produce ethanol (0.36 g/g) and xylitol (1.00 g/g). PMID:23844185

  12. Optimization of CDT-1 and XYL1 expression for balanced co-production of ethanol and xylitol from cellobiose and xylose by engineered Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Jian Zha

    Full Text Available Production of ethanol and xylitol from lignocellulosic hydrolysates is an alternative to the traditional production of ethanol in utilizing biomass. However, the conversion efficiency of xylose to xylitol is restricted by glucose repression, causing a low xylitol titer. To this end, we cloned genes CDT-1 (encoding a cellodextrin transporter and gh1-1 (encoding an intracellular β-glucosidase from Neurospora crassa and XYL1 (encoding a xylose reductase that converts xylose into xylitol from Scheffersomyces stipitis into Saccharomyces cerevisiae, enabling simultaneous production of ethanol and xylitol from a mixture of cellobiose and xylose (main components of lignocellulosic hydrolysates. We further optimized the expression levels of CDT-1 and XYL1 by manipulating their promoters and copy-numbers, and constructed an engineered S. cerevisiae strain (carrying one copy of PGK1p-CDT1 and two copies of TDH3p-XYL1, which showed an 85.7% increase in xylitol production from the mixture of cellobiose and xylose than that from the mixture of glucose and xylose. Thus, we achieved a balanced co-fermentation of cellobiose (0.165 g/L/h and xylose (0.162 g/L/h at similar rates to co-produce ethanol (0.36 g/g and xylitol (1.00 g/g.

  13. Improved ethanol production from xylose in the presence of acetic acid by the overexpression of the HAA1 gene in Saccharomyces cerevisiae.

    Science.gov (United States)

    Sakihama, Yuri; Hasunuma, Tomohisa; Kondo, Akihiko

    2015-03-01

    The hydrolysis of lignocellulosic biomass liberates sugars, primarily glucose and xylose, which are subsequently converted to ethanol by microbial fermentation. The rapid and efficient fermentation of xylose by recombinant Saccharomyces cerevisiae strains is limited by weak acids generated during biomass pretreatment processes. In particular, acetic acid negatively affects cell growth, xylose fermentation rate, and ethanol production. The ability of S. cerevisiae to efficiently utilize xylose in the presence of acetic acid is an essential requirement for the cost-effective production of ethanol from lignocellulosic hydrolysates. Here, an acetic acid-responsive transcriptional activator, HAA1, was overexpressed in a recombinant xylose-fermenting S. cerevisiae strain to yield BY4741X/HAA1. This strain exhibited improved cell growth and ethanol production from xylose under aerobic and oxygen limited conditions, respectively, in the presence of acetic acid. The HAA1p regulon enhanced transcript levels in BY4741X/HAA1. The disruption of PHO13, a p-nitrophenylphosphatase gene, in BY4741X/HAA1 led to further improvement in both yeast growth and the ability to ferment xylose, indicating that HAA1 overexpression and PHO13 deletion act by different mechanisms to enhance ethanol production. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  14. Co-fermentation of cellobiose and xylose by mixed culture of recombinant Saccharomyces cerevisiae and kinetic modeling.

    Science.gov (United States)

    Chen, Yingying; Wu, Ying; Zhu, Baotong; Zhang, Guanyu; Wei, Na

    2018-01-01

    Efficient conversion of cellulosic sugars in cellulosic hydrolysates is important for economically viable production of biofuels from lignocellulosic biomass, but the goal remains a critical challenge. The present study reports a new approach for simultaneous fermentation of cellobiose and xylose by using the co-culture consisting of recombinant Saccharomyces cerevisiae specialist strains. The co-culture system can provide competitive advantage of modularity compared to the single culture system and can be tuned to deal with fluctuations in feedstock composition to achieve robust and cost-effective biofuel production. This study characterized fermentation kinetics of the recombinant cellobiose-consuming S. cerevisiae strain EJ2, xylose-consuming S. cerevisiae strain SR8, and their co-culture. The motivation for kinetic modeling was to provide guidance and prediction of using the co-culture system for simultaneous fermentation of mixed sugars with adjustable biomass of each specialist strain under different substrate concentrations. The kinetic model for the co-culture system was developed based on the pure culture models and incorporated the effects of product inhibition, initial substrate concentration and inoculum size. The model simulations were validated by results from independent fermentation experiments under different substrate conditions, and good agreement was found between model predictions and experimental data from batch fermentation of cellobiose, xylose and their mixtures. Additionally, with the guidance of model prediction, simultaneous co-fermentation of 60 g/L cellobiose and 20 g/L xylose was achieved with the initial cell densities of 0.45 g dry cell weight /L for EJ2 and 0.9 g dry cell weight /L SR8. The results demonstrated that the kinetic modeling could be used to guide the design and optimization of yeast co-culture conditions for achieving simultaneous fermentation of cellobiose and xylose with improved ethanol productivity, which is

  15. Engineering Escherichia coli to grow constitutively on D-xylose using the carbon-efficient Weimberg pathway

    Science.gov (United States)

    Rossoni, Luca; Carr, Reuben; Baxter, Scott; Cortis, Roxann; Thorpe, Thomas; Eastham, Graham; Stephens, Gill

    2018-01-01

    Bio-production of fuels and chemicals from lignocellulosic C5 sugars usually requires the use of the pentose phosphate pathway (PPP) to produce pyruvate. Unfortunately, the oxidation of pyruvate to acetyl-coenzyme A results in the loss of 33 % of the carbon as CO2, to the detriment of sustainability and process economics. To improve atom efficiency, we engineered Escherichia coli to utilize d-xylose constitutively using the Weimberg pathway, to allow direct production of 2-oxoglutarate without CO2 loss. After confirming enzyme expression in vitro, the pathway expression was optimized in vivo using a combinatorial approach, by screening a range of constitutive promoters whilst systematically varying the gene order. A PPP-deficient (ΔxylAB), 2-oxoglutarate auxotroph (Δicd) was used as the host strain, so that growth on d-xylose depended on the expression of the Weimberg pathway, and variants expressing Caulobacter crescentus xylXAB could be selected on minimal agar plates. The strains were isolated and high-throughput measurement of the growth rates on d-xylose was used to identify the fastest growing variant. This strain contained the pL promoter, with C. crescentus xylA at the first position in the synthetic operon, and grew at 42 % of the rate on d-xylose compared to wild-type E. coli using the PPP. Remarkably, the biomass yield was improved by 53.5 % compared with the wild-type upon restoration of icd activity. Therefore, the strain grows efficiently and constitutively on d-xylose, and offers great potential for use as a new host strain to engineer carbon-efficient production of fuels and chemicals via the Weimberg pathway. PMID:29458683

  16. Improvement of Xylose Fermentation Ability under Heat and Acid Co-Stress in Saccharomyces cerevisiae Using Genome Shuffling Technique

    Directory of Open Access Journals (Sweden)

    Kentaro Inokuma

    2017-12-01

    Full Text Available Xylose-assimilating yeasts with tolerance to both fermentation inhibitors (such as weak organic acids and high temperature are required for cost-effective simultaneous saccharification and cofermentation (SSCF of lignocellulosic materials. Here, we demonstrate the construction of a novel xylose-utilizing Saccharomyces cerevisiae strain with improved fermentation ability under heat and acid co-stress using the drug resistance marker-aided genome shuffling technique. The mutagenized genome pools derived from xylose-utilizing diploid yeasts with thermotolerance or acid tolerance were shuffled by sporulation and mating. The shuffled strains were then subjected to screening under co-stress conditions of heat and acids, and the hybrid strain Hyb-8 was isolated. The hybrid strain displayed enhanced xylose fermentation ability in comparison to both parental strains under co-stress conditions of heat and acids. Hyb-8 consumed 33.1 ± 0.6 g/L xylose and produced 11.1 ± 0.4 g/L ethanol after 72 h of fermentation at 38°C with 20 mM acetic acid and 15 mM formic acid. We also performed transcriptomic analysis of the hybrid strain and its parental strains to screen for key genes for multiple stress tolerances. We found that 13 genes, including 5 associated with cellular transition metal ion homeostasis, were significantly upregulated in Hyb-8 compared to levels in both parental strains under co-stress conditions. The hybrid strain Hyb-8 has strong potential for cost-effective SSCF of lignocellulosic materials. Moreover, the transcriptome data gathered in this study will be useful for understanding the mechanisms of multiple tolerance to high temperature and acids in yeast and facilitate the development of robust yeast strains for SSCF.

  17. Fermentation performance of engineered and evolved xylose-fermenting Saccharomyces cerevisiae strains

    DEFF Research Database (Denmark)

    Sonderegger, M.; Jeppsson, M.; Larsson, C.

    2004-01-01

    Lignocellulose hydrolysate is an abundant substrate for bioethanol production. The ideal microorganism for such a fermentation process should combine rapid and efficient conversion of the available carbon sources to ethanol with high tolerance to ethanol and to inhibitory components in the hydrol......Lignocellulose hydrolysate is an abundant substrate for bioethanol production. The ideal microorganism for such a fermentation process should combine rapid and efficient conversion of the available carbon sources to ethanol with high tolerance to ethanol and to inhibitory components...... in the hydrolysate. A particular biological problem are the pentoses, which are not naturally metabolized by the main industrial ethanol producer Saccharomyces cerevisiae. Several recombinant, mutated, and evolved xylose fermenting S. cerevisiae strains have been developed recently. We compare here the fermentation...

  18. Performance testing of Zymomonas mobilis metabolically engineered for cofermentation of glucose, xylose, and arabinose.

    Science.gov (United States)

    Lawford, Hugh G; Rousseau, Joyce D

    2002-01-01

    IOGEN Corporation of Ottawa, Canada, has recently built a 40t/d biomass-to-ethanol demonstration plant adjacent to its enzyme production facility. It has partnered with the University of Toronto to test the C6/C5 cofermenta-tion performance characteristics of the National Renewable Energy Labora-tory's metabolically engineered Zymomonas mobilis using various biomass hydrolysates. IOGEN's feedstocks are primarily agricultural wastes such as corn stover and wheat straw. Integrated recombinant Z. mobilis strain AX101 grows on D-xylose and/or L-arabinose as the sole carbon/energy sources and ferments these pentose sugars to ethanol in high yield. Strain AX101 lacks the tetracycline resistance gene that was a common feature of other recombinant Zm constructs. Genomic integration provides reliable cofermentation performance in the absence of antibiotics, another characteristic making strain AX101 attractive for industrial cellulosic ethanol production. In this work, IOGEN's biomass hydrolysate was simulated by a pure sugar medium containing 6% (w/v) glucose, 3% xylose, and 0.35% arabinose. At a level of 3 g/L (dry solids), corn steep liquor with inorganic nitrogen (0.8 g/L of ammonium chloride or 1.2 g/L of diammonium phosphate) was a cost-effective nutritional supplement. In the absence of acetic acid, the maximum volumetric ethanol productivity of a continuous fermentation at pH 5.0 was 3.54 g/L x h. During prolonged continuous fermentation, the efficiency of sugar-to-ethanol conversion (based on total sugar load) was maintained at >85%. At a level of 0.25% (w/v) acetic acid, the productivity decreased to 1.17 g/L x h at pH 5.5. Unlike integrated, xylose-utilizing rec Zm strain C25, strain AX101 produces less lactic acid as byproduct, owing to the fact that the Escherichia coli arabinose genes are inserted into a region of the host chromosome tentatively assigned to the gene for D-lactic acid dehydrogenase. In pH-controlled batch fermentations with sugar mixtures, the

  19. Enhanced electrochemical performances with a copper/xylose-based carbon composite electrode

    Science.gov (United States)

    Sirisomboonchai, Suchada; Kongparakul, Suwadee; Nueangnoraj, Khanin; Zhang, Haibo; Wei, Lu; Reubroycharoen, Prasert; Guan, Guoqing; Samart, Chanatip

    2018-04-01

    Copper/carbon (Cu/C) composites were prepared through the simple and environmentally benign hydrothermal carbonization of xylose in the presence of Cu2+ ions. The morphology, specific surface area, phase structure and chemical composition were investigated. Using a three-electrode system in 0.1 M H2SO4 aqueous electrolyte, the Cu/C composite (10 wt% Cu) heat-treated at 600 °C gave the highest specific capacitance (316.2 and 350.1 F g-1 at 0.5 A g-1 and 20 mV s-1, respectively). The addition of Cu was the major factor in improving the electrochemical performance, enhancing the specific capacitance more than 30 times that of the C without Cu. Therefore, the Cu/C composite presented promising results in improving biomass-based C electrodes for supercapacitors.

  20. Furfural Synthesis from d-Xylose in the Presence of Sodium Chloride: Microwave versus Conventional Heating.

    Science.gov (United States)

    Xiouras, Christos; Radacsi, Norbert; Sturm, Guido; Stefanidis, Georgios D

    2016-08-23

    We investigate the existence of specific/nonthermal microwave effects for the dehydration reaction of xylose to furfural in the presence of NaCl. Such effects are reported for sugars dehydration reactions in several literature reports. To this end, we adopted three approaches that compare microwave-assisted experiments with a) conventional heating experiments from the literature; b) simulated conventional heating experiments using microwave-irradiated silicon carbide (SiC) vials; and at c) different power levels but the same temperature by using forced cooling. No significant differences in the reaction kinetics are observed using any of these methods. However, microwave heating still proves advantageous as it requires 30 % less forward power compared to conventional heating (SiC vial) to achieve the same furfural yield at a laboratory scale. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Cell growth and hydrogen production on the mixture of xylose and glucose using a novel strain of Clostridium sp. HR-1 isolated from cow dung compost

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ji-Fei; Ren, Nan-Qi; Wang, Ai-Jie; Qiu, Jie; Zhao, Qing-Liang; Feng, Yu-Jie; Liu, Bing-Feng [State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090 (China)

    2010-12-15

    A novel mesophilic hydrogen-producing bacterium was isolated from cow dung compost and designated as Clostridium sp. HR-1 by 16S rRNA gene sequence. The optimum condition for hydrogen production by strain HR-1 was pH of 6.5, temperature of 37 C and yeast extract as nitrogen sources. The strain HR-1 has the ability to utilize kinds of hexose and pentose as carbon sources for growth and H{sub 2} production. Cell growth and hydrogen productivity were investigated for batch fermentation on media containing different ratios of xylose and glucose. Glucose was the preferred substrate in the glucose and xylose mixtures. The high glucose fraction had higher cell biomass production rate. The rate of glucose consumption was higher than xylose consumption, and remained essentially constant independent of xylose content of the mixture. The rate of xylose utilization was decreased with increasing of the glucose fraction. The average H{sub 2} yield and specific H{sub 2} production rates with xylose and glucose are 1.63 mol-H{sub 2}/mol xylose and 11.14-H{sub 2} mmol/h g-cdw, and 2.02 mol-H{sub 2}/mol-glucose and 9.37 mmol-H{sub 2}/h g-cdw, respectively. Using the same initial substrate concentration, the maximum average H{sub 2} yield and specific H{sub 2} production rates with the mixtures of 9 g/l xylose and 3 g/l glucose was 2.01 mol-H{sub 2}/mol-mixed sugar and 12.56 mmol-H{sub 2}/h g-cdw, respectively. During the fermentation, the main soluble microbial products were ethanol and acetate which showed trends with the different ratios of xylose and glucose. (author)

  2. Production of xylose, furfural, fermentable sugars and ethanol from agricultural residues

    Energy Technology Data Exchange (ETDEWEB)

    Singh, A.; Das, K.; Sharma, D.K.

    1984-02-01

    With the developing shortage of petroleum, reliance on biomass as a source of chemicals and fuels will increase. In the present work, bagasse and rice husk were subjected to dilute acid (H2SO4) hydrolysis using pressurised water to obtain furfural and fermentable sugars. Various process conditions such as particle size, solid-liquid ratio, acid concentration, reaction time and temperature have been studied to optimise yields of furfural, xylose and other fermentable sugars. The use of particle sizes smaller than 495 mu m did not further increase the yield of reducing sugars. A solid-liquid ratio of 1:15 was found to be the most suitable for production of reducing sugars. Hydrolysis using 0.4% H2SO4 at 453 K resulted in selective yields (g per 100 g of dried agricultural residues) of xylose from bagasse (22.5%) and rice husk (21.5%). A maximum yield of furfural was obtained using 0.4% H2SO4 at 473 K from bagasse (11.5%) and rice husk (10.9%). It was also found that hydrolysis using 1% H2SO4 at 493 K resulted in maximum yields of total reducing sugar from bagasse (53.5%) and rice husk (50%). The reducing sugars obtained were fermented to ethanol after removal of furfural. The effect of furfural on the fermentation of sugars to ethanol was also studied. Based on these studies, an integrated two-step process for the production of furfural and fermentable sugars could be envisaged. In the first step, using 0.4% H2SO4 at 473 K, furfural could be obtained, while in the second step, the use of 1% H2SO4 at 493 K should result in the production of fermentable sugars. (Refs. 22).

  3. Isolation of xylose isomerases by sequence- and function-based screening from a soil metagenomic library

    Directory of Open Access Journals (Sweden)

    Parachin Nádia

    2011-05-01

    Full Text Available Abstract Background Xylose isomerase (XI catalyses the isomerisation of xylose to xylulose in bacteria and some fungi. Currently, only a limited number of XI genes have been functionally expressed in Saccharomyces cerevisiae, the microorganism of choice for lignocellulosic ethanol production. The objective of the present study was to search for novel XI genes in the vastly diverse microbial habitat present in soil. As the exploitation of microbial diversity is impaired by the ability to cultivate soil microorganisms under standard laboratory conditions, a metagenomic approach, consisting of total DNA extraction from a given environment followed by cloning of DNA into suitable vectors, was undertaken. Results A soil metagenomic library was constructed and two screening methods based on protein sequence similarity and enzyme activity were investigated to isolate novel XI encoding genes. These two screening approaches identified the xym1 and xym2 genes, respectively. Sequence and phylogenetic analyses revealed that the genes shared 67% similarity and belonged to different bacterial groups. When xym1 and xym2 were overexpressed in a xylA-deficient Escherichia coli strain, similar growth rates to those in which the Piromyces XI gene was expressed were obtained. However, expression in S. cerevisiae resulted in only one-fourth the growth rate of that obtained for the strain expressing the Piromyces XI gene. Conclusions For the first time, the screening of a soil metagenomic library in E. coli resulted in the successful isolation of two active XIs. However, the discrepancy between XI enzyme performance in E. coli and S. cerevisiae suggests that future screening for XI activity from soil should be pursued directly using yeast as a host.

  4. Dehydration of D-xylose over SiO2-Al2O3 catalyst: Perspective on the pathways for condensed products

    International Nuclear Information System (INIS)

    You, Su Jin; Park, Eun Duck; Park, Myung-June

    2016-01-01

    This work addresses the kinetic mechanism for the dehydration of D-xylose over the SiO 2 -Al 2 O 3 solid catalyst, where the formation of condensed products is included in addition to the production of furfural and its decomposition. The kinetic modeling and parametric sensitivity show that the isomerization of D-xylose takes place in the early stages of the reaction, followed by the dehydration of isomers. Accordingly, the homogeneous polymerization of isomers is found to be dominant. The developed model is used to evaluate the effects of operating conditions on the catalytic performance; high temperature and D-xylose concentration guarantee high furfural yield.

  5. Mechanisms of Candida biofilm drug resistance

    Science.gov (United States)

    Taff, Heather T; Mitchell, Kaitlin F; Edward, Jessica A; Andes, David R

    2013-01-01

    Candida commonly adheres to implanted medical devices, growing as a resilient biofilm capable of withstanding extraordinarily high antifungal concentrations. As currently available antifungals have minimal activity against biofilms, new drugs to treat these recalcitrant infections are urgently needed. Recent investigations have begun to shed light on the mechanisms behind the profound resistance associated with the biofilm mode of growth. This resistance appears to be multifactorial, involving both mechanisms similar to conventional, planktonic antifungal resistance, such as increased efflux pump activity, as well as mechanisms specific to the biofilm lifestyle. A unique biofilm property is the production of an extracellular matrix. Two components of this material, β-glucan and extracellular DNA, promote biofilm resistance to multiple antifungals. Biofilm formation also engages several stress response pathways that impair the activity of azole drugs. Resistance within a biofilm is often heterogeneous, with the development of a subpopulation of resistant persister cells. In this article we review the molecular mechanisms underlying Candida biofilm antifungal resistance and their relative contributions during various growth phases. PMID:24059922

  6. Activity of Polyphenolic Compounds against Candida glabrata

    Directory of Open Access Journals (Sweden)

    Ricardo Salazar-Aranda

    2015-09-01

    Full Text Available Opportunistic mycoses increase the morbidity and mortality of immuno-compromised patients. Five Candida species have been shown to be responsible for 97% of worldwide cases of invasive candidiasis. Resistance of C. glabrata and C. krusei to azoles has been reported, and new, improved antifungal agents are needed. The current study was designed to evaluatethe activity of various polyphenolic compounds against Candida species. Antifungal activity was evaluated following the M27-A3 protocol of the Clinical and Laboratory Standards Institute, and antioxidant activity was determined using the DPPH assay. Myricetin and baicalein inhibited the growth of all species tested. This effect was strongest against C. glabrata, for which the minimum inhibitory concentration (MIC value was lower than that of fluconazole. The MIC values against C. glabrata for myricitrin, luteolin, quercetin, 3-hydroxyflavone, and fisetin were similar to that of fluconazole. The antioxidant activity of all compounds was confirmed, and polyphenolic compounds with antioxidant activity had the greatest activity against C. glabrata. The structure and position of their hydroxyl groups appear to influence their activity against C. glabrata.

  7. Combinatorial stresses kill pathogenic Candida species

    Science.gov (United States)

    Kaloriti, Despoina; Tillmann, Anna; Cook, Emily; Jacobsen, Mette; You, Tao; Lenardon, Megan; Ames, Lauren; Barahona, Mauricio; Chandrasekaran, Komelapriya; Coghill, George; Goodman, Daniel; Gow, Neil A. R.; Grebogi, Celso; Ho, Hsueh-Lui; Ingram, Piers; McDonagh, Andrew; De Moura, Alessandro P. S.; Pang, Wei; Puttnam, Melanie; Radmaneshfar, Elahe; Romano, Maria Carmen; Silk, Daniel; Stark, Jaroslav; Stumpf, Michael; Thiel, Marco; Thorne, Thomas; Usher, Jane; Yin, Zhikang; Haynes, Ken; Brown, Alistair J. P.

    2012-01-01

    Pathogenic microbes exist in dynamic niches and have evolved robust adaptive responses to promote survival in their hosts. The major fungal pathogens of humans, Candida albicans and Candida glabrata, are exposed to a range of environmental stresses in their hosts including osmotic, oxidative and nitrosative stresses. Significant efforts have been devoted to the characterization of the adaptive responses to each of these stresses. In the wild, cells are frequently exposed simultaneously to combinations of these stresses and yet the effects of such combinatorial stresses have not been explored. We have developed a common experimental platform to facilitate the comparison of combinatorial stress responses in C. glabrata and C. albicans. This platform is based on the growth of cells in buffered rich medium at 30°C, and was used to define relatively low, medium and high doses of osmotic (NaCl), oxidative (H 2O2) and nitrosative stresses (e.g., dipropylenetriamine (DPTA)-NONOate). The effects of combinatorial stresses were compared with the corresponding individual stresses under these growth conditions. We show for the first time that certain combinations of combinatorial stress are especially potent in terms of their ability to kill C. albicans and C. glabrata and/or inhibit their growth. This was the case for combinations of osmotic plus oxidative stress and for oxidative plus nitrosative stress. We predict that combinatorial stresses may be highly signif cant in host defences against these pathogenic yeasts. PMID:22463109

  8. Candida Parapsilosis Arthritis Involving the Ankle in a Diabetes Patient: A Case Report

    International Nuclear Information System (INIS)

    Sung, Jin Kyeong; Chun, Kyung Ah

    2011-01-01

    Candida parapsilosis is a rare opportunistic fungal pathogen of the musculoskeletal region. Immune function of almost all patients is severely disturbed. Most reported cases of septic arthritis of joints by Candida involve the knee, especially Candida parapsilosis. To our knowledge, there has been only one case report of Candida parapsilosis involving the ankle presented on only plain radiography. We report a case of Candida parapsilosis arthritis involving the ankle in a diabetes patient which was shown on MR imaging.

  9. Candida Parapsilosis Arthritis Involving the Ankle in a Diabetes Patient: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Jin Kyeong; Chun, Kyung Ah [Dept. of Radiology, The Catholic University of Korea Uijeongbu St. Mary' s Hospital, Uijeongbu (Korea, Republic of)

    2011-06-15

    Candida parapsilosis is a rare opportunistic fungal pathogen of the musculoskeletal region. Immune function of almost all patients is severely disturbed. Most reported cases of septic arthritis of joints by Candida involve the knee, especially Candida parapsilosis. To our knowledge, there has been only one case report of Candida parapsilosis involving the ankle presented on only plain radiography. We report a case of Candida parapsilosis arthritis involving the ankle in a diabetes patient which was shown on MR imaging.

  10. ISOLASI SPESIES CANDIDA DARI TINJA PENDERITA HIV/AIDS

    Directory of Open Access Journals (Sweden)

    Pudji K Sjarifuddin

    2002-12-01

    Full Text Available Candida is a saprophyte in the human respiratory tract, gastro intestinal tract and also in the debris under the nail. Inpatients with compromised immunity such as HIV-AIDS, Candida is able to cause infection, in this case oral candidosisor esophagitis. In this study fungi were isolated from the stools of HIV/AIDS patients. Samples consisting of 95diarrheic stools from HIV/AIDS patients were investigated for the yeast especially Candida spp. The stools were inoculated onto Sabouraud dextrose agar then the fungi were identified using morphological methods and Chromagarmedium. Yeast colonies were found in 71 (74,74% out of 95 samples from which Candida was 42 44,21%, Geotrichum 24 (25,26%, and mixed of Candida and Geotrichum 3 (3,16%, Rhodotorula and Trichosporon 1(1,05% each. Species of Candida were identified as C. albicans, C. tropicalis, C. krusei, C. guilliermondii, C. glabrata, C. lusitaniae and C. kefyr. Although Candida could be isolated from the diarrheic stools of HIV/AIDS patients but its role on the cause of diarrhea is still questionable.

  11. Clinicopathologic assessment of Candida colonization of oral leukoplakia

    Directory of Open Access Journals (Sweden)

    Reena Sarkar

    2014-01-01

    Full Text Available Background: Leukoplakia is the most common premalignant lesion of the oral mucosa. We studied the colonization of Candida in oral leukoplakia using direct microscopy, culture and histopathology to determine if there is a statistical correlation between Candida invasion and the clinical appearance and presence of epithelial dysplasia in leukoplakia. Methods: Samples were collected from 40 patients with oral leukoplakia and 21 controls. The swabs collected were used to inoculate Sabouraud′s dextrose agar slant and for direct microscopy with Gram′s stain. Culture growths were subjected to germ tube and corn meal agar tests to differentiate between Candida albicans and non-albicans groups. Biopsies were also done in all patients for histopathological confirmation; Gomori′s methanamine silver stain was used to identify fungal invasion of lesional epithelium. Results and Conclusions: Nineteen cases of leukoplakia showed Candida on direct smears, compared to 3 controls. Eighteen cases and one control showed growth of Candida on culture. Non-homogenous leukoplakia showed a higher positivity rate on microscopy and culture than homogenous lesions. All these correlations were statistically significant. Forty percent of leukoplakia cases were simultaneously positive for Candida on direct microscopy, culture and histopathologic evaluation. No significant difference was found between non-dysplastic and distinctly dysplastic lesions with respect to Candida detection on microscopy or culture.

  12. Clinicopathologic assessment of Candida colonization of oral leukoplakia.

    Science.gov (United States)

    Sarkar, Reena; Rathod, G P

    2014-01-01

    Leukoplakia is the most common premalignant lesion of the oral mucosa. We studied the colonization of Candida in oral leukoplakia using direct microscopy, culture and histopathology to determine if there is a statistical correlation between Candida invasion and the clinical appearance and presence of epithelial dysplasia in leukoplakia. Samples were collected from 40 patients with oral leukoplakia and 21 controls. The swabs collected were used to inoculate Sabouraud's dextrose agar slant and for direct microscopy with Gram's stain. Culture growths were subjected to germ tube and corn meal agar tests to differentiate between Candida albicans and non-albicans groups. Biopsies were also done in all patients for histopathological confirmation; Gomori's methanamine silver stain was used to identify fungal invasion of lesional epithelium. Nineteen cases of leukoplakia showed Candida on direct smears, compared to 3 controls. Eighteen cases and one control showed growth of Candida on culture. Non-homogenous leukoplakia showed a higher positivity rate on microscopy and culture than homogenous lesions. All these correlations were statistically significant. Forty percent of leukoplakia cases were simultaneously positive for Candida on direct microscopy, culture and histopathologic evaluation. No significant difference was found between non-dysplastic and distinctly dysplastic lesions with respect to Candida detection on microscopy or culture.

  13. Prevalence of Candida Species in Erosive Oral Lichen Planus

    Directory of Open Access Journals (Sweden)

    Masoumeh Mehdipour

    2010-03-01

    Full Text Available Background and aims. The clinical management of oral lichen planus poses considerable difficulties to the clinician. In recent years, researchers have focused on the presence of pathogenic microorganisms such as Candida albicans in the patients with refractory lichen planus. The aim of the present study was to investigate the prevalence of candida species in the erosive oral lichen planus lesions. Materials and methods. Twenty-one patients with erosive oral lichen planus and twenty-one healthy individuals aged 18-60 were randomly selected; samples were taken from the tongue, saliva and buccal mucosa with swab friction. Theses samples were sent to the laboratory for determining the presence of candida species in cultures and direct examination method. Results. No significant difference was found between healthy individuals and patients with erosive lichen planus regarding presence of candida species. The type of candida in the evaluated samples was Candida albicans in both healthy and patient groups. Conclusion. According to the results, candida was not confirmed as an etiologic factor for erosive lichen planus lesions.

  14. Fluconazole resistance in Candida species: a current perspective

    Directory of Open Access Journals (Sweden)

    Berkow EL

    2017-07-01

    Full Text Available Elizabeth L Berkow, Shawn R Lockhart Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA Abstract: Candida albicans and the emerging non-albicans Candida spp. have significant clinical relevance among many patient populations. Current treatment guidelines include fluconazole as a primary therapeutic option for the treatment of these infections, but it is only fungistatic against Candida spp. and both inherent and acquired resistance to fluconazole have been reported. Such mechanisms of resistance include increased drug efflux, alteration or increase in the drug target, and development of compensatory pathways for producing the target sterol, ergosterol. While many mechanisms of resistance observed in C. albicans are also found in the non-albicans species, there are also important and unexpected differences between species. Furthermore, mechanisms of fluconazole resistance in emerging Candida spp., including the global health threat Candida auris, are largely unknown. In order to preserve the utility of one of our fundamental antifungal drugs, fluconazole, it is essential that we fully appreciate the manner by which Candida spp. manifest resistance to it. Keywords: Candida, fluconazole resistance, ERG11, drug efflux, ergosterol

  15. Rapid identification of drug resistant Candida species causing recurrent vulvovaginal candidiasis.

    Science.gov (United States)

    Diba, Kambiz; Namaki, Atefeh; Ayatolahi, Haleh; Hanifian, Haleh

    2012-01-01

    Some yeast agents including Candida albicans, Candida tropicalis and Candida glabrata have a role in recurrent vulvovaginal candidiasis. We studied the frequency of both common and recurrent vulvovaginal candidiasis in symptomatic cases which were referred to Urmia Medical Sciences University related gynecology clinics using morphologic and molecular methods. The aim of this study was the identification of Candida species isolated from recurrent vulvovaginal candidiasis cases using a rapid and reliable molecular method. Vaginal swabs obtained from each case, were cultured on differential media including cornmeal agar and CHROM agar Candida. After 48 hours at 37℃, the cultures were studied for growth characteristics and color production respectively. All isolates were identified using the molecular method of PCR - restriction fragment length polymorphism. Among all clinical specimens, we detected 19 ( 16 % ) non fungal agents, 87 ( 82.1 % ) yeasts and 2 ( 1.9 % ) multiple infections. The yeast isolates identified morphologically included Candida albicans ( n = 62 ), Candida glabrata ( n = 9 ), Candida tropicalis ( n = 8 ), Candida parapsilosis ( n = 8 ) and Candida guilliermondii and Candida krusei ( n = 1 each ). We also obtained very similar results for Candida albicans, Candida glabrata and Candida tropicalis as the most common clinical isolates, by using PCR - Restriction Fragment Length Polymorphism. Use of two differential methods, morphologic and molecular, enabled us to identify most medically important Candida species which particularly cause recurrent vulvovaginal candidiasis.

  16. Candida albicans versus Candida dubliniensis: Why Is C. albicans More Pathogenic?

    LENUS (Irish Health Repository)

    Moran, Gary P

    2012-01-01

    Candida albicans and Candida dubliniensis are highly related pathogenic yeast species. However, C. albicans is far more prevalent in human infection and has been shown to be more pathogenic in a wide range of infection models. Comparison of the genomes of the two species has revealed that they are very similar although there are some significant differences, largely due to the expansion of virulence-related gene families (e.g., ALS and SAP) in C. albicans, and increased levels of pseudogenisation in C. dubliniensis. Comparative global gene expression analyses have also been used to investigate differences in the ability of the two species to tolerate environmental stress and to produce hyphae, two traits that are likely to play a role in the lower virulence of C. dubliniensis. Taken together, these data suggest that C. dubliniensis is in the process of undergoing reductive evolution and may have become adapted for growth in a specialized anatomic niche.

  17. [Fungal (Candida) infections in the immunocompromised pediatric patient].

    Science.gov (United States)

    Bruce Diemond, J; Lopez, C; Huerta Romano, F; Montiel Castillo, C

    2008-11-01

    Today, mycotic infections in immunocompromised patients are mainly caused by Candida spp. and Aspergillus spp. The patients most sensitive to these infections are those with some kind of cell-mediated immunity quantitative or qualitative alteration (i.e., blood-related cancer, primary or secondary neutropenia, immunosuppressive disease or therapy, etc.). Candida infection in the immunosupressed patient comprises a wide range of serious diseases such as candidemia, chronic disseminated candididasis, endocarditis, meningitis and endophthalmitis. Therefore, infection by Candida spp. is considered secondary to the technological and medical advances which extend the life of patients with chronic diseases. Copyright 2008 Prous Science, S.A.U. or its licensors. All rights reserved.

  18. Miltefosine inhibits Candida albicans and non-albicans Candida spp. biofilms and impairs the dispersion of infectious cells.

    Science.gov (United States)

    Vila, Taissa; Ishida, Kelly; Seabra, Sergio Henrique; Rozental, Sonia

    2016-11-01

    Candida spp. can adhere to and form biofilms over different surfaces, becoming less susceptible to antifungal treatment. Resistance of biofilms to antifungal agents is multifactorial and the extracellular matrix (ECM) appears to play an important role. Among the few available antifungals for treatment of candidaemia, only the lipid formulations of amphotericin B (AmB) and the echinocandins are effective against biofilms. Our group has previously demonstrated that miltefosine has an important effect against Candida albicans biofilms. Thus, the aim of this work was to expand the analyses of the in vitro antibiofilm activity of miltefosine to non-albicans Candida spp. Miltefosine had significant antifungal activity against planktonic cells and the development of biofilms of C. albicans, Candida parapsilosis, Candida tropicalis and Candida glabrata. The activity profile in biofilms was superior to fluconazole and was similar to that of AmB and caspofungin. Biofilm-derived cells with their ECM extracted became as susceptible to miltefosine as planktonic cells, confirming the importance of the ECM in the biofilm resistant behaviour. Miltefosine also inhibited biofilm dispersion of cells at the same concentration needed to inhibit planktonic cell growth. The data obtained in this work reinforce the potent inhibitory activity of miltefosine on biofilms of the four most pathogenic Candida spp. and encourage further studies for the utilisation of this drug and/or structural analogues on biofilm-related infections. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  19. Performance of chromogenic media for Candida in rapid presumptive identification of Candida species from clinical materials

    OpenAIRE

    Pravin Charles, M. V.; Kali, Arunava; Joseph, Noyal Mariya

    2015-01-01

    Background: In perspective of the worldwide increase in a number of immunocompromised patients, the need for identification of Candida species has become a major concern. The development of chromogenic differential media, introduced recently, facilitate rapid speciation. However, it can be employed for routine mycology workup only after an exhaustive evaluation of its benefit and cost effectiveness. This study was undertaken to evaluate the benefit and cost effectiveness of chromogenic media ...

  20. Differentiation between Candida albicans and Candida dubliniensis using hypertonic Sabouraud broth and tobacco agar

    Directory of Open Access Journals (Sweden)

    Fabíola Silveira-Gomes

    2011-08-01

    Full Text Available INTRODUCTION: Opportunistic fungal infections in immunocompromised hosts are caused by Candida species, and the majority of such infections are due to Candida albicans. However, the emerging pathogen Candida dubliniensis demonstrates several phenotypic characteristics in common with C. albicans, such as production of germ tubes and chlamydospores, calling attention to the development of stable resistance to fluconazole in vitro. The aim of this study was to evaluate the performance of biochemistry identification in the differentiating between C. albicans and C. dubliniensis, by phenotyping of yeast identified as C. albicans. METHODS: Seventy-nine isolates identified as C. albicans by the API system ID 32C were grown on Sabouraud dextrose agar at 30°C for 24-48h and then inoculated on hypertonic Sabouraud broth and tobacco agar. RESULTS: Our results showed that 17 (21.5% isolates were growth-inhibited on hypertonic Sabouraud broth, a phenotypic trait inconsistent with C. albicans in this medium. However, the results observed on tobacco agar showed that only 9 (11.4% of the growth-inhibited isolates produced characteristic colonies of C. dubliniensis (rough colonies, yellowish-brown with abundant fragments of hyphae and chlamydospores. CONCLUSIONS: The results suggest that this method is a simple tool for screening C. albicans and non-albicans yeast and for verification of automated identification.

  1. Differentiation between Candida albicans and Candida dubliniensis using hypertonic Sabouraud broth and tobacco agar.

    Science.gov (United States)

    Silveira-Gomes, Fabíola; Sarmento, Dayse Nogueira; Espírito-Santo, Elaine Patrícia Tavares do; Souza, Nádia de Oliveira; Pinto, Thifany Mendes; Marques-da-Silva, Silvia Helena

    2011-01-01

    Opportunistic fungal infections in immunocompromised hosts are caused by Candida species, and the majority of such infections are due to Candida albicans. However, the emerging pathogen Candida dubliniensis demonstrates several phenotypic characteristics in common with C. albicans, such as production of germ tubes and chlamydospores, calling attention to the development of stable resistance to fluconazole in vitro. The aim of this study was to evaluate the performance of biochemistry identification in the differentiating between C. albicans and C. dubliniensis, by phenotyping of yeast identified as C. albicans. Seventy-nine isolates identified as C. albicans by the API system ID 32C were grown on Sabouraud dextrose agar at 30°C for 24-48h and then inoculated on hypertonic Sabouraud broth and tobacco agar. Our results showed that 17 (21.5%) isolates were growth-inhibited on hypertonic Sabouraud broth, a phenotypic trait inconsistent with C. albicans in this medium. However, the results observed on tobacco agar showed that only 9 (11.4%) of the growth-inhibited isolates produced characteristic colonies of C. dubliniensis (rough colonies, yellowish-brown with abundant fragments of hyphae and chlamydospores). The results suggest that this method is a simple tool for screening C. albicans and non-albicans yeast and for verification of automated identification.

  2. Purification and germination of Candida albicans and Candida dubliniensis chlamydospores cultured in liquid media.

    LENUS (Irish Health Repository)

    Citiulo, Francesco

    2009-10-01

    Candida albicans and Candida dubliniensis are the only Candida sp. that have been observed to produce chlamydospores. The function of these large, thick-walled cells is currently unknown. In this report, we describe the production and purification of chlamydospores from these species in defined liquid media. Staining with the fluorescent dye FUN-1 indicated that chlamydospores are metabolically active cells, but that metabolic activity is undetectable in chlamydospores that are >30 days old. However, 5-15-day-old chlamydospores could be induced to produce daughter chlamydospores, blastospores, pseudohyphae and true hyphae depending on the incubation conditions used. Chlamydospores that were preinduced to germinate were also observed to escape from murine macrophages following phagocytosis, suggesting that these structures may be viable in vivo. Mycelium-attached and purified chlamydospores rapidly lost their viability in water and when subjected to dry stress, suggesting that they are unlikely to act as long-term storage structures. Instead, our data suggest that chlamydospores represent an alternative specialized form of growth by C. albicans and C. dubliniensis.

  3. Biophysical Effects of a Polymeric Biosurfactant in Candida krusei and Candida albicans Cells.

    Science.gov (United States)

    Ferreira, Gabriella Freitas; Dos Santos Pinto, Bruna Lorrana; Souza, Eliene Batista; Viana, José Lima; Zagmignan, Adrielle; Dos Santos, Julliana Ribeiro Alves; Santos, Áquila Rodrigues Costa; Tavares, Priscila Batista; Denadai, Ângelo Márcio Leite; Monteiro, Andrea Souza

    2016-12-01

    This study evaluated the effects of a polymeric biosurfactant produced by Trichosporon montevideense CLOA72 in the adhesion of Candida albicans and Candida krusei cells to human buccal epithelial cells and its interference in biofilm formation by these strains. The biofilm inhibition by biosurfactant (25 mg/mL) in C. krusei and C. albicans in polystyrene was reduced up to 79.5 and 85 %, respectively. In addition, the zeta potential and hydrodynamic diameter of the yeasts altered as a function of the biosurfactant concentration added to the cell suspension. The changes in the cell surface characteristics and the interface modification can contribute to the inhibition of the initial adherence of yeasts cells to the surface. In addition, the analyses of the biofilm matrix and planktonic cell surfaces demonstrated differences in carbohydrate and protein concentrations for the two studied strains, which may contribute to the modulation of cell adhesion or consolidation of biofilms, especially in C. krusei. This study suggests a possible application of the of CLOA72 biosurfactant in inhibiting the adhesion and formation of biofilms on biological surfaces by yeasts of the Candida genus.

  4. Silver colloidal nanoparticles: antifungal effect against adhered cells and biofilms of Candida albicans and Candida glabrata.

    Science.gov (United States)

    Monteiro, D R; Gorup, L F; Silva, S; Negri, M; de Camargo, E R; Oliveira, R; Barbosa, D B; Henriques, M

    2011-08-01

    The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n = 2) and C. glabrata (n = 2) grown in suspension following the Clinical Laboratory Standards Institute microbroth dilution method. SN were applied to adhered cells (2 h) or biofilms (48 h) and after 24 h of contact their effect was assessed by enumeration of colony forming units (CFUs) and quantification of total biomass (by crystal violet staining). The MIC results showed that SN were fungicidal against all strains tested at very low concentrations (0.4-3.3 μg ml(-1)). Furthermore, SN were more effective in reducing biofilm biomass when applied to adhered cells (2 h) than to pre-formed biofilms (48 h), with the exception of C. glabrata ATCC, which in both cases showed a reduction ∼90%. Regarding cell viability, SN were highly effective on adhered C. glabrata and respective biofilms. On C. albicans the effect was not so evident but there was also a reduction in the number of viable biofilm cells. In summary, SN may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.

  5. Global Transcriptome Sequencing Identifies Chlamydospore Specific Markers in Candida albicans and Candida dubliniensis

    LENUS (Irish Health Repository)

    Palige, Katja

    2013-04-15

    Candida albicans and Candida dubliniensis are pathogenic fungi that are highly related but differ in virulence and in some phenotypic traits. During in vitro growth on certain nutrient-poor media, C. albicans and C. dubliniensis are the only yeast species which are able to produce chlamydospores, large thick-walled cells of unknown function. Interestingly, only C. dubliniensis forms pseudohyphae with abundant chlamydospores when grown on Staib medium, while C. albicans grows exclusively as a budding yeast. In order to further our understanding of chlamydospore development and assembly, we compared the global transcriptional profile of both species during growth in liquid Staib medium by RNA sequencing. We also included a C. albicans mutant in our study which lacks the morphogenetic transcriptional repressor Nrg1. This strain, which is characterized by its constitutive pseudohyphal growth, specifically produces masses of chlamydospores in Staib medium, similar to C. dubliniensis. This comparative approach identified a set of putatively chlamydospore-related genes. Two of the homologous C. albicans and C. dubliniensis genes (CSP1 and CSP2) which were most strongly upregulated during chlamydospore development were analysed in more detail. By use of the green fluorescent protein as a reporter, the encoded putative cell wall related proteins were found to exclusively localize to C. albicans and C. dubliniensis chlamydospores. Our findings uncover the first chlamydospore specific markers in Candida species and provide novel insights in the complex morphogenetic development of these important fungal pathogens.

  6. Adaptation of the xylose fermenting yeast Saccharomyces cerevisiae F12 for improving ethanol production in different fed-batch SSF processes.

    Science.gov (United States)

    Tomás-Pejó, E; Ballesteros, M; Oliva, J M; Olsson, L

    2010-11-01

    An efficient fermenting microorganism for bioethanol production from lignocellulose is highly tolerant to the inhibitors released during pretreatment and is able to ferment efficiently both glucose and xylose. In this study, directed evolution was employed to improve the xylose fermenting Saccharomyces cerevisiae F12 strain for bioethanol production at high substrate loading. Adapted and parental strains were compared with respect to xylose consumption and ethanol production. Adaptation led to an evolved strain more tolerant to the toxic compounds present in the medium. When using concentrated prehydrolysate from steam-pretreated wheat straw with high inhibitor concentration, an improvement of 65 and 20% in xylose consumption and final ethanol concentration, respectively, were achieved using the adapted strain. To address the need of high substrate loadings, fed-batch SSF experiments were performed and an ethanol concentration as high as 27.4 g/l (61% of the theoretical) was obtained with 11.25% (w/w) of water insoluble solids (WIS).

  7. Overexpression of pyruvate decarboxylase in the yeast Hansenula polymorpha results in increased ethanol yield in high-temperature fermentation of xylose.

    Science.gov (United States)

    Ishchuk, Olena P; Voronovsky, Andriy Y; Stasyk, Oleh V; Gayda, Galina Z; Gonchar, Mykhailo V; Abbas, Charles A; Sibirny, Andriy A

    2008-11-01

    Improvement of xylose fermentation is of great importance to the fuel ethanol industry. The nonconventional thermotolerant yeast Hansenula polymorpha naturally ferments xylose to ethanol at high temperatures (48-50 degrees C). Introduction of a mutation that impairs ethanol reutilization in H. polymorpha led to an increase in ethanol yield from xylose. The native and heterologous (Kluyveromyces lactis) PDC1 genes coding for pyruvate decarboxylase were expressed at high levels in H. polymorpha under the control of the strong constitutive promoter of the glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH). This resulted in increased pyruvate decarboxylase activity and improved ethanol production from xylose. The introduction of multiple copies of the H. polymorpha PDC1 gene driven by the strong constitutive promoter led to a 20-fold increase in pyruvate decarboxylase activity and up to a threefold elevation of ethanol production.

  8. Relative Abundances of Candida albicans and Candida glabrata in In Vitro Coculture Biofilms Impact Biofilm Structure and Formation.

    Science.gov (United States)

    Olson, Michelle L; Jayaraman, Arul; Kao, Katy C

    2018-04-15

    Candida is a member of the normal human microbiota and often resides on mucosal surfaces such as the oral cavity or the gastrointestinal tract. In addition to their commensality, Candida species can opportunistically become pathogenic if the host microbiota is disrupted or if the host immune system becomes compromised. An important factor for Candida pathogenesis is its ability to form biofilm communities. The two most medically important species- Candida albicans and Candida glabrata -are often coisolated from infection sites, suggesting the importance of Candida coculture biofilms. In this work, we report that biofilm formation of the coculture population depends on the relative ratio of starting cell concentrations of C. albicans and C. glabrata When using a starting ratio of C. albicans to C. glabrata of 1:3, ∼6.5- and ∼2.5-fold increases in biofilm biomass were observed relative to those of a C. albicans monoculture and a C. albicans / C. glabrata ratio of 1:1, respectively. Confocal microscopy analysis revealed the heterogeneity and complex structures composed of long C. albicans hyphae and C. glabrata cell clusters in the coculture biofilms, and reverse transcription-quantitative PCR (qRT-PCR) studies showed increases in the relative expression of the HWP1 and ALS3 adhesion genes in the C. albicans / C. glabrata 1:3 biofilm compared to that in the C. albicans monoculture biofilm. Additionally, only the 1:3 C. albicans / C. glabrata biofilm demonstrated an increased resistance to the antifungal drug caspofungin. Overall, the results suggest that interspecific interactions between these two fungal pathogens increase biofilm formation and virulence-related gene expression in a coculture composition-dependent manner. IMPORTANCE Candida albicans and Candida glabrata are often coisolated during infection, and the occurrence of coisolation increases with increasing inflammation, suggesting possible synergistic interactions between the two Candida species in

  9. Data for rapid ethanol production at elevated temperatures by engineered thermotolerant Kluyveromyces marxianus via the NADP(H-preferring xylose reductase–xylitol dehydrogenase pathway

    Directory of Open Access Journals (Sweden)

    Biao Zhang

    2015-12-01

    Full Text Available A thermo-tolerant NADP(H-preferring xylose pathway was constructed in Kluyveromyces marxianus for ethanol production with xylose at elevated temperatures (Zhang et al., 2015 [25]. Ethanol production yield and efficiency was enhanced by pathway engineering in the engineered strains. The constructed strain, YZJ088, has the ability to co-ferment glucose and xylose for ethanol and xylitol production, which is a critical step toward enabling economic biofuel production from lignocellulosic biomass. This study contains the fermentation results of strains using the metabolic pathway engineering procedure. The ethanol-producing abilities of various yeast strains under various conditions were compared, and strain YZJ088 showed the highest production and fastest productivity at elevated temperatures. The YZJ088 xylose fermentation results indicate that it fermented well with xylose at either low or high inoculum size. When fermented with an initial cell concentration of OD600=15 at 37 °C, YZJ088 consumed 200 g/L xylose and produced 60.07 g/L ethanol; when the initial cell concentration was OD600=1 at 37 °C, YZJ088 consumed 98.96 g/L xylose and produced 33.55 g/L ethanol with a productivity of 0.47 g/L/h. When fermented with 100 g/L xylose at 42 °C, YZJ088 produced 30.99 g/L ethanol with a productivity of 0.65 g/L/h, which was higher than that produced at 37 °C.

  10. Silencing ß1,2-xylosyltransferase in transgenic tomato fruits reveals xylose as constitutive component of IgE binding epitopes

    Directory of Open Access Journals (Sweden)

    Kathrin Elisabeth Paulus

    2011-08-01

    Full Text Available Complex plant N-glycans containing β1,2-xylose and core α1,3-fucose are regarded as the major class of the so-called ‘carbohydrate cross-reactive determinants’ reactive with IgE antibodies in sera of many allergic patients, but their clinical relevance is still under debate. Plant glycosyltransferases, β1,2-xylosyltransferase (XylT and core α1,3-fucosyltransferase (FucT are responsible for the transfer of β1,2-linked xylose and core α1,3-linked fucose residues to N-glycans of glycoproteins, respectively. To test the clinical relevance of ß 1,2-xylose containing epitopes, expression of the tomato β1,2-xylosyltransferase was down-regulated by RNA interference (RNAi in transgenic plants. Fruits harvested from these transgenic plants were analysed for accumulation of XylT mRNA, abundance of ß1,2-xylose epitopes and their allergenic potential. Based on qPCR analysis XylT mRNA levels were reduced up to 10-fold in independent transgenic lines as compared to untransformed control, whereas no xylosylated N-glycans could be revealed by MS analysis. Immunoblotting using anti-xylose-specific IgG antibodies revealed a strong reduction of ß1,2-xylose containing epitopes. Incubating protein extracts from untransformed controls and XylT_RNAi plants with sera from tomato allergic patients showed a patient-specific reduction in IgE binding, indicating a reduced allergenic potential of XylT_RNAi tomato fruits, in vitro. To elucidate the clinical relevance of ß1,2-xylose containing complex N-glycans skin prick tests were performed demonstrating a reduced responsiveness of tomato allergic patients, in vivo. This study provides strong evidence for the clinical relevance of ß1,2-xylose containing epitopes in vivo.

  11. Isolation of a variant of Candida albicans.

    Science.gov (United States)

    Buckley, H R; Price, M R; Daneo-Moore, L

    1982-01-01

    During the course of Candida albicans antigen production, a variant of this organism was encountered which did not produce hyphae at 37 degrees C. Presented here are some of the characteristics of this variant. It produces hyphae at 25 degrees C on cornmeal agar and synthetic medium plus N-acetylglucosamine and Tween 80. At 37 degrees C, it does not produce hyphae on these media, although C. albicans normally does produce hyphae under these circumstances. In liquid synthetic medium, this variant does not produce hyphae at 37 degrees C. The variant strain was analyzed for DNA, RNA, protein content, and particle size. After 50 to 70 h in balanced exponential-phase growth, particle size distribution was narrow, and there were no differences in the DNA, RNA, or protein content per particle in the two strains. When balanced exponential-phase cultures were brought into stationary phase, both strains contained the same amount of DNA per cell. Images PMID:6752021

  12. Isolation of a variant of Candida albicans.

    Science.gov (United States)

    Buckley, H R; Price, M R; Daneo-Moore, L

    1982-09-01

    During the course of Candida albicans antigen production, a variant of this organism was encountered which did not produce hyphae at 37 degrees C. Presented here are some of the characteristics of this variant. It produces hyphae at 25 degrees C on cornmeal agar and synthetic medium plus N-acetylglucosamine and Tween 80. At 37 degrees C, it does not produce hyphae on these media, although C. albicans normally does produce hyphae under these circumstances. In liquid synthetic medium, this variant does not produce hyphae at 37 degrees C. The variant strain was analyzed for DNA, RNA, protein content, and particle size. After 50 to 70 h in balanced exponential-phase growth, particle size distribution was narrow, and there were no differences in the DNA, RNA, or protein content per particle in the two strains. When balanced exponential-phase cultures were brought into stationary phase, both strains contained the same amount of DNA per cell.

  13. Development of Candida-Specific Real-Time PCR Assays for the Detection and Identification of Eight Medically Important Candida Species.

    Science.gov (United States)

    Zhang, Jing; Hung, Guo-Chiuan; Nagamine, Kenjiro; Li, Bingjie; Tsai, Shien; Lo, Shyh-Ching

    2016-01-01

    Culture-based identification methods have been the gold standard for the diagnosis of fungal infection. Currently, molecular technologies such as real-time PCR assays with short turnaround time can provide desirable alternatives for the rapid detection of Candida microbes. However, most of the published PCR primer sets are not Candida specific and likely to amplify DNA from common environmental contaminants, such as Aspergillus microbes. In this study, we designed pan-Candida primer sets based on the ribosomal DNA-coding regions conserved within Candida but distinct from those of Aspergillus and Penicillium. We demonstrate that the final two selected pan-Candida primer sets would not amplify Aspergillus DNA and could be used to differentiate eight medically important Candida pathogens in real-time PCR assays based on their melting profiles, with a sensitivity of detection as low as 10 fg of Candida genomic DNA. Moreover, we further evaluated and selected species-specific primer sets covering Candida albicans, Candida glabrata, Candida tropicalis, and Candida dubliniensis and show that they had high sensitivity and specificity. These real-time PCR primer sets could potentially be assembled into a single PCR array for the rapid detection of Candida species in various clinical settings, such as corneal transplantation.

  14. Catechol biodegradation kinetics using Candida parapsilopsis

    Directory of Open Access Journals (Sweden)

    Maurício Rigo

    2010-04-01

    Full Text Available This study evaluated the biodegradation of catechol by a yeast strain of Candida parapsilopsis in standard medium in Erlenmeyer flasks. Results shown that the highest concentration of catechol caused the longer lag period, demonstrating that acclimatized cultures could completely degrade an initial catechol concentration of 910 mg/L within 48 h. Haldane's model validated the experimental data adequately for growth kinetics over the studied catechol concentration ranges of 36 to 910 mg/L. The constants obtained for this model were µmax = 0.246 h-1, Ks = 16.95 mg/L and Ki = 604.85 mg/L.Neste trabalho foi estudada a biodegradação de catecol em frascos de Erlenmeyers em água residuária sintética pela levedura Candida parapsilopsis. As respostas dos ensaios cinéticos mostraram que altas concentrações de catecol ocasionaram uma fase lag longa para a levedura. Portanto, a aclimatização da cultura de levedura empregada para biodegradação de catecol é de fundamental importância, sendo possível reduzir toda a concentração inicial de catecol da água residuária sintética de 910 mg/L em 48 horas. Os dados experimentais da cinética de biodegradação do catecol foram ajustados pelo modelo de Haldane adequadamente, sobre a faixa de concentração de catecol investigada de 36 a 910 mg/L. Os parâmetros cinéticos obtidos do modelo de Haldane foram: µmax = 0,246 h-1, Ks = 16,95 mg/L e Ki = 604,85 mg/L.

  15. Effects of acid impregnated steam explosion process on xylose recovery and enzymatic conversion of cellulose in corncob.

    Science.gov (United States)

    Fan, Xiaoguang; Cheng, Gang; Zhang, Hongjia; Li, Menghua; Wang, Shizeng; Yuan, Qipeng

    2014-12-19

    Corncob residue is a cellulose-rich byproduct obtained from industrial xylose production via dilute acid hydrolysis processes. Enzymatic hydrolysis of cellulose in acid hydrolysis residue of corncob (AHRC) is often less efficient without further pretreatment. In this work, the process characteristics of acid impregnated steam explosion were studied in conjunction with a dilute acid process, and their effects on physiochemical changes and enzymatic saccharification of corncob residue were compared. With the acid impregnated steam explosion process, both higher xylose recovery and higher cellulose conversion were obtained. The maximum conversion of cellulose in acid impregnated steam explosion residue of corncob (ASERC) reached 85.3%, which was 1.6 times higher than that of AHRC. Biomass compositional analysis showed similar cellulose and lignin content in ASERC and AHRC. XRD analysis demonstrated comparable crystallinity of ASERC and AHRC. The improved enzymatic hydrolysis efficiency was attributed to higher porosity in ASERC, measured by mercury porosimetry. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. The intra- and extracellular proteome of Aspergillus niger growing on defined medium with xylose or maltose as carbon substrate

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    Wissing Josef

    2010-04-01

    Full Text Available Abstract Background The filamentous fungus Aspergillus niger is well-known as a producer of primary metabolites and extracellular proteins. For example, glucoamylase is the most efficiently secreted protein of Aspergillus niger, thus the homologous glucoamylase (glaA promoter as well as the glaA signal sequence are widely used for heterologous protein production. Xylose is known to strongly repress glaA expression while maltose is a potent inducer of glaA promoter controlled genes. For a more profound understanding of A. niger physiology, a comprehensive analysis of the intra- and extracellular proteome of Aspergillus niger AB1.13 growing on defined medium with xylose or maltose as carbon substrate was carried out using 2-D gel electrophoresis/Maldi-ToF and nano-HPLC MS/MS. Results The intracellular proteome of A. niger growing either on xylose or maltose in well-aerated controlled bioreactor cultures revealed striking similarities. In both cultures the most abundant intracellular protein was the TCA cycle enzyme malate-dehydrogenase. Moreover, the glycolytic enzymes fructose-bis-phosphate aldolase and glyceraldehyde-3-phosphate-dehydrogenase and the flavohemoglobin FhbA were identified as major proteins in both cultures. On the other hand, enzymes involved in the removal of reactive oxygen species, such as superoxide dismutase and peroxiredoxin, were present at elevated levels in the culture growing on maltose but only in minor amounts in the xylose culture. The composition of the extracellular proteome differed considerably depending on the carbon substrate. In the secretome of the xylose-grown culture, a variety of plant cell wall degrading enzymes were identified, mostly under the control of the xylanolytic transcriptional activator XlnR, with xylanase B and ferulic acid esterase as the most abundant ones. The secretome of the maltose-grown culture did not contain xylanolytic enzymes, instead high levels of catalases were found and

  17. The intra- and extracellular proteome of Aspergillus niger growing on defined medium with xylose or maltose as carbon substrate.

    Science.gov (United States)

    Lu, Xin; Sun, Jibin; Nimtz, Manfred; Wissing, Josef; Zeng, An-Ping; Rinas, Ursula

    2010-04-20

    The filamentous fungus Aspergillus niger is well-known as a producer of primary metabolites and extracellular proteins. For example, glucoamylase is the most efficiently secreted protein of Aspergillus niger, thus the homologous glucoamylase (glaA) promoter as well as the glaA signal sequence are widely used for heterologous protein production. Xylose is known to strongly repress glaA expression while maltose is a potent inducer of glaA promoter controlled genes. For a more profound understanding of A. niger physiology, a comprehensive analysis of the intra- and extracellular proteome of Aspergillus niger AB1.13 growing on defined medium with xylose or maltose as carbon substrate was carried out using 2-D gel electrophoresis/Maldi-ToF and nano-HPLC MS/MS. The intracellular proteome of A. niger growing either on xylose or maltose in well-aerated controlled bioreactor cultures revealed striking similarities. In both cultures the most abundant intracellular protein was the TCA cycle enzyme malate-dehydrogenase. Moreover, the glycolytic enzymes fructose-bis-phosphate aldolase and glyceraldehyde-3-phosphate-dehydrogenase and the flavohemoglobin FhbA were identified as major proteins in both cultures. On the other hand, enzymes involved in the removal of reactive oxygen species, such as superoxide dismutase and peroxiredoxin, were present at elevated levels in the culture growing on maltose but only in minor amounts in the xylose culture. The composition of the extracellular proteome differed considerably depending on the carbon substrate. In the secretome of the xylose-grown culture, a variety of plant cell wall degrading enzymes were identified, mostly under the control of the xylanolytic transcriptional activator XlnR, with xylanase B and ferulic acid esterase as the most abundant ones. The secretome of the maltose-grown culture did not contain xylanolytic enzymes, instead high levels of catalases were found and glucoamylase (multiple spots) was identified as the most

  18. Goodbye warts, hello vitiligo: Candida antigen-induced depigmentation.

    Science.gov (United States)

    Wilmer, Erin N; Burkhart, Craig N; Morrell, Dean S

    2013-01-01

    Depigmentation after the use of topical immune modulators is a rare but reported event. Herein we present what is to our knowledge the first case of vitiligo at a site of Candida antigen injection. © 2012 Wiley Periodicals, Inc.

  19. Recurrent Candida albicans Ventriculitis Treated with Intraventricular Liposomal Amphotericin B

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    Demet Toprak

    2015-01-01

    Full Text Available Central nervous system (CNS infection with Candida is rare but significant because of its high morbidity and mortality. When present, it is commonly seen among immunocompromised and hospitalized patients. Herein, we describe a case of a four-year-old boy with acute lymphoblastic leukemia (ALL who experienced recurrent Candida albicans meningitis. The patient was treated successfully with intravenous liposomal amphotericin B at first attack, but 25 days after discharge he was readmitted to hospital with symptoms of meningitis. Candida albicans was grown in CFS culture again and cranial magnetic resonance imaging (MRI showed ventriculitis. We administered liposomal amphotericin B both intravenously and intraventricularly and favorable result was achieved without any adverse effects. Intraventricular amphotericin B may be considered for the treatment of recurrent CNS Candida infections in addition to intravenous administration.

  20. In vitro synergism of simvastatin and fluconazole against Candida species

    Directory of Open Access Journals (Sweden)

    Everardo Albuquerque Menezes

    2012-08-01

    Full Text Available Systemic fungal infections are responsible for high mortality rates. Several species of fungi may be involved, but Candida spp. is the most prevalent. Simvastatin is used to lower cholesterol and also exhibits antifungal action. The aim of this study was to evaluate the synergistic action of simvastatin with fluconazole against strains of Candida spp. Susceptibility testing was performed according to protocol M27-A3, by broth microdilution method and the synergistic effect of simvastatin and fluconazole was calculated based on FICI (Fractional Inhibitory Concentration Index. Eleven strains were evaluated, and simvastatin showed a synergistic effect with fluconazole against 10 (91% of the Candida spp. strains tested. Simvastatin may be a valuable drug in the treatment of systemic infections caused by Candida spp.

  1. Budding off: bringing functional genomics to Candida albicans

    Science.gov (United States)

    Anderson, Matthew Z.

    2016-01-01

    Candida species are the most prevalent human fungal pathogens, with Candida albicans being the most clinically relevant species. Candida albicans resides as a commensal of the human gastrointestinal tract but is a frequent cause of opportunistic mucosal and systemic infections. Investigation of C. albicans virulence has traditionally relied on candidate gene approaches, but recent advances in functional genomics have now facilitated global, unbiased studies of gene function. Such studies include comparative genomics (both between and within Candida species), analysis of total RNA expression, and regulation and delineation of protein–DNA interactions. Additionally, large collections of mutant strains have begun to aid systematic screening of clinically relevant phenotypes. Here, we will highlight the development of functional genomics in C. albicans and discuss the use of these approaches to addressing both commensalism and pathogenesis in this species. PMID:26424829

  2. Coutilization of D-Glucose, D-Xylose, and L-Arabinose in Saccharomyces cerevisiae by Coexpressing the Metabolic Pathways and Evolutionary Engineering

    Directory of Open Access Journals (Sweden)

    Chengqiang Wang

    2017-01-01

    Full Text Available Efficient and cost-effective fuel ethanol production from lignocellulosic materials requires simultaneous cofermentation of all hydrolyzed sugars, mainly including D-glucose, D-xylose, and L-arabinose. Saccharomyces cerevisiae is a traditional D-glucose fermenting strain and could utilize D-xylose and L-arabinose after introducing the initial metabolic pathways. The efficiency and simultaneous coutilization of the two pentoses and D-glucose for ethanol production in S. cerevisiae still need to be optimized. Previously, we constructed an L-arabinose-utilizing S. cerevisiae BSW3AP. In this study, we further introduced the XI and XR-XDH metabolic pathways of D-xylose into BSW3AP to obtain D-glucose, D-xylose, and L-arabinose cofermenting strain. Benefits of evolutionary engineering: the resulting strain BSW4XA3 displayed a simultaneous coutilization of D-xylose and L-arabinose with similar consumption rates, and the D-glucose metabolic capacity was not decreased. After 120 h of fermentation on mixed D-glucose, D-xylose, and L-arabinose, BSW4XA3 consumed 24% more amounts of pentoses and the ethanol yield of mixed sugars was increased by 30% than that of BSW3AP. The resulting strain BSW4XA3 was a useful chassis for further enhancing the coutilization efficiency of mixed sugars for bioethanol production.

  3. Dynamic flux balance modeling of microbial co-cultures for efficient batch fermentation of glucose and xylose mixtures.

    Science.gov (United States)

    Hanly, Timothy J; Henson, Michael A

    2011-02-01

    Sequential uptake of pentose and hexose sugars that compose lignocellulosic biomass limits the ability of pure microbial cultures to efficiently produce value-added bioproducts. In this work, we used dynamic flux balance modeling to examine the capability of mixed cultures of substrate-selective microbes to improve the utilization of glucose/xylose mixtures and to convert these mixed substrates into products. Co-culture simulations of Escherichia coli strains ALS1008 and ZSC113, engineered for glucose and xylose only uptake respectively, indicated that improvements in batch substrate consumption observed in previous experimental studies resulted primarily from an increase in ZSC113 xylose uptake relative to wild-type E. coli. The E. coli strain ZSC113 engineered for the elimination of glucose uptake was computationally co-cultured with wild-type Saccharomyces cerevisiae, which can only metabolize glucose, to determine if the co-culture was capable of enhanced ethanol production compared to pure cultures of wild-type E. coli and the S. cerevisiae strain RWB218 engineered for combined glucose and xylose uptake. Under the simplifying assumption that both microbes grow optimally under common environmental conditions, optimization of the strain inoculum and the aerobic to anaerobic switching time produced an almost twofold increase in ethanol productivity over the pure cultures. To examine the effect of reduced strain growth rates at non-optimal pH and temperature values, a break even analysis was performed to determine possible reductions in individual strain substrate uptake rates that resulted in the same predicted ethanol productivity as the best pure culture. © 2010 Wiley Periodicals, Inc.

  4. A novel method to prepare L-Arabinose from xylose mother liquor by yeast-mediated biopurification

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    Lin Shuangjun

    2011-06-01

    Full Text Available Abstract Background L-arabinose is an important intermediate for anti-virus drug synthesis and has also been used in food additives for diets-controlling in recent years. Commercial production of L-arabinose is a complex progress consisting of acid hydrolysis of gum arabic, followed by multiple procedures of purification, thus making high production cost. Therefore, there is a biotechnological and commercial interest in the development of new cost-effective and high-performance methods for obtaining high purity grade L-arabinose. Results An alternative, economical method for purifying L-arabinose from xylose mother liquor was developed in this study. After screening 306 yeast strains, a strain of Pichia anomala Y161 was selected as it could effectively metabolize other sugars but not L-arabinose. Fermentation in a medium containing xylose mother liquor permitted enrichment of L-arabinose by a significant depletion of other sugars. Biochemical analysis of this yeast strain confirmed that its poor capacity for utilizing L-arabinose was due to low activities of the enzymes required for the metabolism of this sugar. Response surface methodology was employed for optimization the fermentation conditions in shake flask cultures. The optimum conditions were: 75 h fermentation time, at 32.5°C, in a medium containing 21% (v/v xylose mother liquor. Under these conditions, the highest purity of L-arabinose reached was 86.1% of total sugar, facilitating recovery of white crystalline L-arabinose from the fermentation medium by simple methods. Conclusion Yeast-mediated biopurification provides a dynamic method to prepare high purity of L-arabinose from the feedstock solution xylose mother liqour, with cost-effective and high-performance properties.

  5. Analysis of gene evolution and metabolic pathways using the Candida Gene Order Browser

    LENUS (Irish Health Repository)

    Fitzpatrick, David A

    2010-05-10

    Abstract Background Candida species are the most common cause of opportunistic fungal infection worldwide. Recent sequencing efforts have provided a wealth of Candida genomic data. We have developed the Candida Gene Order Browser (CGOB), an online tool that aids comparative syntenic analyses of Candida species. CGOB incorporates all available Candida clade genome sequences including two Candida albicans isolates (SC5314 and WO-1) and 8 closely related species (Candida dubliniensis, Candida tropicalis, Candida parapsilosis, Lodderomyces elongisporus, Debaryomyces hansenii, Pichia stipitis, Candida guilliermondii and Candida lusitaniae). Saccharomyces cerevisiae is also included as a reference genome. Results CGOB assignments of homology were manually curated based on sequence similarity and synteny. In total CGOB includes 65617 genes arranged into 13625 homology columns. We have also generated improved Candida gene sets by merging\\/removing partial genes in each genome. Interrogation of CGOB revealed that the majority of tandemly duplicated genes are under strong purifying selection in all Candida species. We identified clusters of adjacent genes involved in the same metabolic pathways (such as catabolism of biotin, galactose and N-acetyl glucosamine) and we showed that some clusters are species or lineage-specific. We also identified one example of intron gain in C. albicans. Conclusions Our analysis provides an important resource that is now available for the Candida community. CGOB is available at http:\\/\\/cgob.ucd.ie.

  6. Candida parapsilosis meningitis associated with Gliadel (BCNU) wafer implants.

    LENUS (Irish Health Repository)

    O'Brien, Deirdre

    2012-02-01

    A 58-year old male presented with meningitis associated with subgaleal and subdural collections 6 weeks following a temporal craniotomy for resection of recurrent glioblastoma multiforme and Gliadel wafer implantation. Candida parapsilosis was cultured from cerebrospinal fluid (CSF) and Gliadel wafers removed during surgical debridement. He was successfully treated with liposomal amphotericin B. To our knowledge, this is the first reported case of Candida parapsilosis meningitis secondary to Gliadel wafer placement.

  7. Candida parapsilosis meningitis associated with Gliadel (BCNU) wafer implants.

    LENUS (Irish Health Repository)

    O'brien, Deirdre

    2010-12-15

    A 58-year old male presented with meningitis associated with subgaleal and subdural collections 6 weeks following a temporal craniotomy for resection of recurrent glioblastoma multiforme and Gliadel wafer implantation. Candida parapsilosis was cultured from cerebrospinal fluid (CSF) and Gliadel wafers removed during surgical debridement. He was successfully treated with liposomal amphotericin B. To our knowledge, this is the first reported case of Candida parapsilosis meningitis secondary to Gliadel wafer placement.

  8. Otomastoiditis caused by Candida auris: Case report and literature review.

    Science.gov (United States)

    Choi, Hyoung Il; An, Jin; Hwang, Jae Joon; Moon, Soo-Youn; Son, Jun Seong

    2017-08-01

    Fungal otomastoiditis is a rare disease, but can be fatal for immunocompromised patients. Recently, there have been increasing cases of otologic infection caused by Candida auris. Candida auris can be easily misdiagnosed for other species and treatment is difficult due to multidrug resistance. Clinician should be aware of this rare pathogen, and it should be treated with appropriate antifungal agent with surgical debridement. © 2017 Blackwell Verlag GmbH.

  9. The first cases of Candida auris candidaemia in Oman.

    Science.gov (United States)

    Mohsin, Jalila; Hagen, Ferry; Al-Balushi, Zainab A M; de Hoog, G Sybren; Chowdhary, Anuradha; Meis, Jacques F; Al-Hatmi, Abdullah M S

    2017-09-01

    Candida auris has been recognised as a problematic healthcare-associated emerging yeast which is often misidentified as Candida haemulonii by commercial systems. Correct early identification of C. auris is important for appropriate antifungal treatment and implementing effective infection control measures. Here we report emergence of the first C. auris cases in Oman, initially misidentified as C. haemulonii. © 2017 Blackwell Verlag GmbH.

  10. Candida na saliva de pacientes hemofílicos brasileiros

    OpenAIRE

    Pereira, Claudio Maranhão; Pires, Fábio Ramôa; Corrêa, Maria Elvira Pizzigatti; di Hipólito Júnior, Osvaldo; Almeida, Oslei Paes de

    2004-01-01

    Hemophilia is a common hereditary hemorrhagic disorder, however little is known about the oral microflora of hemophilic patients. The aim of this study was to quantify the Candida and identify its species in non-stimulated saliva of hemophilic patients, and consider its relationship with clinical factors influencing Candida carriage. This study comprised evaluation of 86 hemophilic patients of the Hematology Center/UNICAMP and 43 healthy subjects as controls. All patients were submitted to an...

  11. Effects of Inhibitors on the Transcriptional Profiling of Gluconobater oxydans NL71 Genes after Biooxidation of Xylose into Xylonate

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    Yong Xu

    2017-04-01

    Full Text Available D-Xylonic acid belongs to the top 30 biomass-based platform chemicals and represents a promising application of xylose. Until today, Gluconobacter oxydans NL71 is the most efficient microbe capable of fermenting xylose into xylonate. However, its growth is seriously inhibited when concentrated lignocellulosic hydrolysates are used as substrates due to the presence of various degraded compounds formed during biomass pretreatment. Three critical lignocellulosic inhibitors were thereby identified, i.e., formic acid, furfural, and 4-hydroxybenzaldehyde. As microbe fermentation is mostly regulated at the genome level, four groups of cell transcriptomes were obtained for a comparative investigation by RNA sequencing of a control sample with samples treated separately with the above-mentioned inhibitors. The digital gene expression profiles screened 572, 714 genes, and 408 DEGs was obtained by the comparisons among four transcriptomes. A number of genes related to the different functional groups showed characteristic expression patterns induced by three inhibitors, in which 19 genes were further tested and confirmed by qRT-PCR. We extrapolated many differentially expressed genes that could explain the cellular responses to the inhibitory effects. We provide results that enable the scientific community to better define the molecular processes involved in the microbes' responses to lignocellulosic inhibitors during the cellular biooxidation of xylose into xylonic acid.

  12. Ethanol fermentation by xylose-assimilating Saccharomyces cerevisiae using sugars in a rice straw liquid hydrolysate concentrated by nanofiltration.

    Science.gov (United States)

    Sasaki, Kengo; Sasaki, Daisuke; Sakihama, Yuri; Teramura, Hiroshi; Yamada, Ryosuke; Hasunuma, Tomohisa; Ogino, Chiaki; Kondo, Akihiko

    2013-11-01

    Concentrating sugars using membrane separation, followed by ethanol fermentation by recombinant xylose-assimilating Saccharomyces cerevisiae, is an attractive technology. Three nanofiltration membranes (NTR-729HF, NTR-7250, and ESNA3) were effective in concentrating glucose, fructose, and sucrose from dilute molasses solution and no permeation of sucrose. The separation factors of acetate, formate, furfural, and 5-hydroxymethyl furfural, which were produced by dilute acid pretreatment of rice straw, over glucose after passage through these three membranes were 3.37-11.22, 4.71-20.27, 4.32-16.45, and 4.05-16.84, respectively, at pH 5.0, an applied pressure of 1.5 or 2.0 MPa, and 25 °C. The separation factors of these fermentation inhibitors over xylose were infinite, as there was no permeation of xylose. Ethanol production from approximately two-times concentrated liquid hydrolysate using recombinant S. cerevisiae was double (5.34-6.44 g L(-1)) that compared with fermentation of liquid hydrolysate before membrane separation (2.75 g L(-1)). Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Catalytic conversion of xylose and corn stalk into furfural over carbon solid acid catalyst in γ-valerolactone.

    Science.gov (United States)

    Zhang, Tingwei; Li, Wenzhi; Xu, Zhiping; Liu, Qiyu; Ma, Qiaozhi; Jameel, Hasan; Chang, Hou-min; Ma, Longlong

    2016-06-01

    A novel carbon solid acid catalyst was synthesized by the sulfonation of carbonaceous material which was prepared by carbonization of sucrose using 4-BDS as a sulfonating agent. TEM, N2 adsorption-desorption, elemental analysis, XPS and FT-IR were used to characterize the catalyst. Then, the catalyst was applied for the conversion of xylose and corn stalk into furfural in GVL. The influence of the reaction time, temperature and dosage of catalyst on xylose dehydration were also investigated. The Brønsted acid catalyst exhibited high activity in the dehydration of xylose, with a high furfural yield of 78.5% at 170°C in 30min. What's more, a 60.6% furfural yield from corn stalk was achieved in 100min at 200°C. The recyclability of the sulfonated carbon catalyst was perfect, and it could be reused for 5times without the loss of furfural yields. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Highly efficient production of L-lactic acid from xylose by newly isolated Bacillus coagulans C106.

    Science.gov (United States)

    Ye, Lidan; Zhou, Xingding; Hudari, Mohammad Sufian Bin; Li, Zhi; Wu, Jin Chuan

    2013-03-01

    Cost-effective production of optically pure lactic acid from lignocellulose sugars is commercially attractive but challenging. Bacillus coagulans C106 was isolated from environment and used to produce l-lactic acid from xylose at 50°C and pH 6.0 in mineral salts medium containing 1-2% (w/v) of yeast extract without sterilizing the medium before fermentation. In batch fermentation with 85g/L of xylose, lactic acid titer and productivity reached 83.6g/L and 7.5g/Lh, respectively. When fed-batch (120+80+60g/L) fermentation was applied, they reached 215.7g/L and 4.0g/Lh, respectively. In both cases, the lactic acid yield and optical purity reached 95% and 99.6%, respectively. The lactic acid titer and productivity on xylose are the highest among those ever reported. Ca(OH)2 was found to be a better neutralizing agent than NaOH in terms of its giving higher lactic acid titer (1.2-fold) and productivity (1.8-fold) under the same conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Gene expression cross-profiling in genetically modified industrial Saccharomyces cerevisiae strains during high-temperature ethanol production from xylose.

    Science.gov (United States)

    Ismail, Ku Syahidah Ku; Sakamoto, Takatoshi; Hatanaka, Haruyo; Hasunuma, Tomohisa; Kondo, Akihiko

    2013-01-10

    Production of ethanol from xylose at high temperature would be an economical approach since it reduces risk of contamination and allows both the saccharification and fermentation steps in SSF to be running at elevated temperature. Eight recombinant xylose-utilizing Saccharomyces cerevisiae strains developed from industrial strains were constructed and subjected to high-temperature fermentation at 38 °C. The best performing strain was sun049T, which produced up to 15.2 g/L ethanol (63% of the theoretical production), followed by sun048T and sun588T, both with 14.1 g/L ethanol produced. Via transcriptomic analysis, expression profiling of the top three best ethanol producing strains compared to a negative control strain, sun473T, led to the discovery of genes in common that were regulated in the same direction. Identification of the 20 most highly up-regulated and the 20 most highly down-regulated genes indicated that the cells regulate their central metabolism and maintain the integrity of the cell walls in response to high temperature. We also speculate that cross-protection in the cells occurs, allowing them to maintain ethanol production at higher concentration under heat stress than the negative controls. This report provides further transcriptomics information in the interest of producing a robust microorganism for high-temperature ethanol production utilizing xylose. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Multidrug-Resistant Candida: Epidemiology, Molecular Mechanisms, and Treatment.

    Science.gov (United States)

    Arendrup, Maiken Cavling; Patterson, Thomas F

    2017-08-15

    Invasive Candida infections remain an important cause of morbidity and mortality, especially in hospitalized and immunocompromised or critically ill patients. A limited number of antifungal agents from only a few drug classes are available to treat patients with these serious infections. Resistance can be either intrinsic or acquired. Resistance mechanisms are not exchanged between Candida; thus, acquired resistance either emerges in response to an antifungal selection pressure in the individual patient or, more rarely, occur due to horizontal transmission of resistant strains between patients. Although multidrug resistance is uncommon, increasing reports of multidrug resistance to the azoles, echinocandins, and polyenes have occurred in several Candida species, most notably Candida glabrata and more recently Candida auris. Drivers are overall antifungal use, subtherapeutic drug levels at sites of infection/colonization, drug sequestration in the biofilm matrix, and, in the setting of outbreaks, suboptimal infection control. Moreover, recent research suggests that DNA mismatch repair gene mutations may facilitate acquisition of resistance mutations in C. glabrata specifically. Diagnosis of antifungal-resistant Candida infections is critical to the successful management of patients with these infections. Reduction of unnecessary use of antifungals via antifungal stewardship is critical to limit multidrug resistance emergence. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

  17. [The relevance of Candida spp. in chronic periodontal disease].

    Science.gov (United States)

    Razina, I N; Chesnokova, M G; Nedoseko, V B

    The aim of the study was to assess the correlation of Candida spp. incidence in periodontal tissues with various clinical manifestations of chronic periodontal disease (CPD). Ninety patients with CPD were included in the study in which Candida spp. was evaluated in periodontal pockets content and gingival biopsy material. In severe CPD more Candida spp. were seen in gingival biopsy than in periodontal pockets (p=0.0006). Candida spp. incidence and quantity correlated directly with the disease grade showing incidence increase from 40 to 73.3% and quantity increase from 0.8±0.18 до 3.6±0.49 lg CFU/ml in light and severe CPD, correspondingly Candida spp. had statistically significant association with cyanotic gingival color (p=0.0018), tongue plaque and swelling (р=0.0042), lip exfoliation (р=0.0030), periodontal pockets depth >5 mm (р=0.0030), oral mucosa hyperemia (р=0.0157), alveolar bone destruction >1/2 of root length (р=0.0157). These data prove the relevance of Candida spp. and mycological assessment of gingival biopsy in CPD patients.

  18. Cellulolytic enzyme expression and simultaneous conversion of lignocellulosic sugars into ethanol and xylitol by a new Candida tropicalis strain.

    Science.gov (United States)

    Mattam, Anu Jose; Kuila, Arindam; Suralikerimath, Niranjan; Choudary, Nettem; Rao, Peddy V C; Velankar, Harshad Ravindra

    2016-01-01

    Lignocellulosic ethanol production involves major steps such as thermochemical pretreatment of biomass, enzymatic hydrolysis of pre-treated biomass and the fermentation of released sugars into ethanol. At least two different organisms are conventionally utilized for producing cellulolytic enzymes and for ethanol production through fermentation, whereas in the present study a single yeast isolate with the capacity to simultaneously produce cellulases and xylanases and ferment the released sugars into ethanol and xylitol has been described. A yeast strain isolated from soil samples and identified as Candida tropicalis MTCC 25057 expressed cellulases and xylanases over a wide range of temperatures (32 and 42 °C) and in the presence of different cellulosic substrates [carboxymethylcellulose and wheat straw (WS)]. The studies indicated that the cultivation of yeast at 42 °C in pre-treated hydrolysate containing 0.5 % WS resulted in proportional expression of cellulases (exoglucanases and endoglucanases) at concentrations of 114.1 and 97.8 U g(-1) ds, respectively. A high xylanase activity (689.3 U g(-1) ds) was also exhibited by the yeast under similar growth conditions. Maximum expression of cellulolytic enzymes by the yeast occurred within 24 h of incubation. Of the sugars released from biomass after pretreatment, 49 g L(-1) xylose was aerobically converted into 15.8 g L(-1) of xylitol. In addition, 25.4 g L(-1) glucose released after the enzymatic hydrolysis of biomass was fermented by the same yeast to obtain an ethanol titer of 7.3 g L(-1). During the present study, a new strain of C. tropicalis was isolated and found to have potential for consolidated bioprocessing (CBP) applications. The strain could grow in a wide range of process conditions (temperature, pH) and in the presence of lignocellulosic inhibitors such as furfural, HMF and acetic acid. The new yeast produced cellulolytic enzymes over a wide temperature range and in the presence of

  19. The importance of genus Candida in human samples

    Directory of Open Access Journals (Sweden)

    Bojić-Miličević Gordana M.

    2008-01-01

    Full Text Available Microbiology is a rapidly changing field. As new researches and experiences broaden our knowledge, changes in the approach to diagnosis and therapy have become necessary and appropriate. Recommended dosage of drugs, method and duration of administration, as well as contraindications to use, evolve over time all drugs. Over the last 2 decades, Candida species have emerged as causes of substantial morbidity and mortality in hospitalized individuals. Isolation of Candida from blood or other sterile sites, excluding the urinary tract, defines invasive candidiasis. Candida species are currently the fourth most common cause of bloodstream infections (that is, candidemia in U.S. hospitals and occur primarily in the intensive care unit (ICU, where candidemia is recognized in up to 1% of patients and where deep-seated Candida infections are recognized in an additional 1 to 2% of patients. Despite the introduction of newer anti-Candida agents, invasive candidiasis continues to have an attributable mortality rate of 40 to 49%; excess ICU and hospital stays of 12.7 days and 15.5 days, respectively, and increased care costs. Postmortem studies suggest that death rates related to invasive candidiasis might, in fact, be higher than those described because of undiagnosed and therefore untreated infection. The diagnosis of invasive candidiasis remains challenging for both clinicians and microbiologists. Reasons for missed diagnoses include nonspecific risk factors and clinical manifestations, low sensitivity of microbiological culture techniques, and unavailability of deep tissue cultures because of risks associated with the invasive procedures used to obtain them. Thus, a substantial proportion of invasive candidiasis in patients in the ICU is assumed to be undiagnosed and untreated. Yet even when invasive candidiasis is diagnosed, culture diagnosis delays treatment for 2 to 3 days, which contributes to mortality. Interventions that do not rely on a specific

  20. Biobutanol production by Clostridium acetobutylicum using xylose recovered from birch Kraft black liquor.

    Science.gov (United States)

    Kudahettige-Nilsson, Rasika L; Helmerius, Jonas; Nilsson, Robert T; Sjöblom, Magnus; Hodge, David B; Rova, Ulrika

    2015-01-01

    Acetone-butanol-ethanol (ABE) fermentation was studied using acid-hydrolyzed xylan recovered from hardwood Kraft black liquor by CO2 acidification as the only carbon source. Detoxification of hydrolyzate using activated carbon was conducted to evaluate the impact of inhibitor removal and fermentation. Xylose hydrolysis yields as high as 18.4% were demonstrated at the highest severity hydrolysis condition. Detoxification using active carbon was effective for removal of both phenolics (76-81%) and HMF (38-52%). Batch fermentation of the hydrolyzate and semi-defined P2 media resulted in a total solvent yield of 0.12-0.13g/g and 0.34g/g, corresponding to a butanol concentration of 1.8-2.1g/L and 7.3g/L respectively. This work is the first study of a process for the production of a biologically-derived biofuel from hemicelluloses solubilized during Kraft pulping and demonstrates the feasibility of utilizing xylan recovered directly from industrial Kraft pulping liquors as a feedstock for biological production of biofuels such as butanol. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Resistencia de levaduras del género Candida al fluconazol Candida yeast´s resistance to fluconazol

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    Carlos Hernando Gómez Quintero

    2010-12-01

    Full Text Available Las infecciones por levaduras del género Candida sp. son cada vez más prevalentes en pacientes hospitalizados, especialmente en grupos de mayor riesgo como pueden ser pacientes con neoplasia hematológica bajo tratamiento de quimioterapia y en cuidados intensivos. La resistencia de Candida sp. representa un reto terapéutico que deja un menor número de posibilidades para el tratamiento de estas infecciones que se caracterizan, a su vez, por una alta morbimortalidad. Esta revisión describe los mecanismos de resistencia de Candida sp. a fluconazol y los factores de riesgo para la adquisición de éstos.Yeast infections of the genus Candida sp are becoming more prevalent in hospitalized patients, especially in high risk groups such as patients with hematologic malignancy undergoing chemotherapy and in intensive care units. Candida sp's resistance represents a therapeutic challenge that leaves fewer opportunities for the treatment of these infections which are characterized by high morbidity and mortality. This review describes Candida sp's resistance mechanisms to fluconazole and the risk factors for their acquisition.

  2. Candida guilliermondii as the aetiology of candidosis Candida guilliermondii como agente de candidose

    Directory of Open Access Journals (Sweden)

    Alessandro Comarú Pasqualotto

    2006-06-01

    Full Text Available Candida guilliermondii is one of the components of human microbiota. This yeast has been infrequently associated with human infections, which may be related to its low pathogenicity. The aim of this study was to provide clinical and epidemiological data for patients infected with C. guilliermondii at Santa Casa Complexo Hospitalar, Brazil. From October 1997 to October 2003, C. guilliermondii was isolated from clinical samples from 11 patients. Three patients were excluded because the isolation of the yeast represented colonisation. Specimens from the eight patients included in the study corresponded to blood (n = 5, ascitis fluid (n = 2, and oesophagus biopsy (n = 1. Three patients (37.5% had major immunosuppressed conditions, including solid organ transplantation, AIDS, and leukaemia. Previous use of antibiotics occurred in 87.5%. Main invasive medical procedures were central venous catheter (50.0%, abdominal surgery (25.0%, and peritoneal dialysis (50.0%. No susceptibility data was obtained. Although risk factors for candidaemia were similar amongst patients infected by with C. guilliermondii or other Candida species, mortality associated with C. guilliermondii was significantly lower.Candida guilliermondii é um dos componentes da microbiota humana e infecções associadas com esta levedura têm sido incomuns, o que pode ser atribuído a sua baixa patogenicidade. O objetivo deste trabalho foi documentar aspectos clínico-epidemiológicos em pacientes que tiveram C. guilliermondii isolada a partir de amostras biológicas. O estudo foi conduzido na Santa Casa Complexo Hospitalar, Brasil. Durante outubro de 1997 e outubro de 2003, C. guilliermondii foi isolada de 11 pacientes, três dos quais foram excluídos por se apresentarem apenas colonizados. Espécimes clínicos corresponderam a sangue (n = 5, líquido de ascite (n = 2 e biópsia de esôfago (n = 1. Três pacientes eram imunodeprimidos, incluindo transplante de órgãos sólidos, SIDA e

  3. Production of medium-chain-length polyhydroxyalkanoates by sequential feeding of xylose and octanoic acid in engineered Pseudomonas putida KT2440

    Directory of Open Access Journals (Sweden)

    Le Meur Sylvaine

    2012-08-01

    Full Text Available Abstract Background Pseudomonas putida KT2440 is able to synthesize large amounts of medium-chain-length polyhydroxyalkanoates (mcl-PHAs. To reduce the substrate cost, which represents nearly 50% of the total PHA production cost, xylose, a hemicellulose derivate, was tested as the growth carbon source in an engineered P. putida KT2440 strain. Results The genes encoding xylose isomerase (XylA and xylulokinase (XylB from Escherichia coli W3110 were introduced into P. putida KT2440. The recombinant KT2440 exhibited a XylA activity of 1.47 U and a XylB activity of 0.97 U when grown on a defined medium supplemented with xylose. The cells reached a maximum specific growth rate of 0.24 h-1 and a final cell dry weight (CDW of 2.5 g L-1 with a maximal yield of 0.5 g CDW g-1 xylose. Since no mcl-PHA was accumulated from xylose, mcl-PHA production can be controlled by the addition of fatty acids leading to tailor-made PHA compositions. Sequential feeding strategy was applied using xylose as the growth substrate and octanoic acid as the precursor for mcl-PHA production. In this way, up to 20% w w-1 of mcl-PHA was obtained. A yield of 0.37 g mcl-PHA per g octanoic acid was achieved under the employed conditions. Conclusions Sequential feeding of relatively cheap carbohydrates and expensive fatty acids is a practical way to achieve more cost-effective mcl-PHA production. This study is the first reported attempt to produce mcl-PHA by using xylose as the growth substrate. Further process optimizations to achieve higher cell density and higher productivity of mcl-PHA should be investigated. These scientific exercises will undoubtedly contribute to the economic feasibility of mcl-PHA production from renewable feedstock.

  4. Rutas de glicosilación en Candida albicans: circuitos reguladores y efectos sobre virulencia

    OpenAIRE

    Domínguez Cantero, María del Pilar

    2011-01-01

    [ES]Esta tesis trata sobre las rutas de glicosilación en Candida albicans: circuitos reguladores y efectos sobre virulencia. [EN]This thesis is about glycosylation pathways in Candida albicans: regulatory circuits and effects on virulence.

  5. Value of Candida serum markers in patients with invasive candidiasis after myeloablative chemotherapy.

    NARCIS (Netherlands)

    Lunel, F.M.; Mennink-Kersten, M.A.S.H.; Ruegebrink, D.; Lee, H.A.L. van der; Donnelly, J.P.; Blijlevens, N.M.A.; Verweij, P.E.

    2009-01-01

    Invasive Candida infections are associated with a significant morbidity and mortality. Detection of circulating biomarkers has been shown to precede conventional diagnostic methods, which is important in improving outcome. We investigated the performance of multiple biomarkers using Candida antigen

  6. Value of Candida serum markers in patients with invasive candidiasis after myeloablative chemotherapy

    NARCIS (Netherlands)

    Lunel, Frans M. Verduyn; Mennink-Kersten, Monique A. S. H.; Ruegebrink, Dorien; van der Lee, Henrich A. L.; Donnelly, J. Peter; Blijlevens, Nicole M. A.; Verweij, Paul E.

    Invasive Candida infections are associated with a significant morbidity and mortality. Detection of circulating biomarkers has been shown to precede conventional diagnostic methods, which is important in improving outcome. We investigated the performance of multiple biomarkers using Candida antigen

  7. Molecular identification of candida species isolated from women with vulvovaginal candidiasis: brief report

    Directory of Open Access Journals (Sweden)

    Maryam Khanmohamadi

    2017-10-01

    Conclusion: Regarding to the results of this study, C. albicans was the most common Candida species, isolated from patients with vulvovaginal candidiasis and approximately 30% of this infection causing by non-albicans species of Candida.

  8. Assimilation of NAD(+) precursors in Candida glabrata.

    Science.gov (United States)

    Ma, Biao; Pan, Shih-Jung; Zupancic, Margaret L; Cormack, Brendan P

    2007-10-01

    The yeast pathogen Candida glabrata is a nicotinamide adenine dinucleotide (NAD(+)) auxotroph and its growth depends on the environmental supply of vitamin precursors of NAD(+). C. glabrata salvage pathways defined in this article allow NAD(+) to be synthesized from three compounds - nicotinic acid (NA), nicotinamide (NAM) and nicotinamide riboside (NR). NA is salvaged through a functional Preiss-Handler pathway. NAM is first converted to NA by nicotinamidase and then salvaged by the Preiss-Handler pathway. Salvage of NR in C. glabrata occurs via two routes. The first, in which NR is phosphorylated by the NR kinase Nrk1, is independent of the Preiss-Handler pathway. The second is a novel pathway in which NR is degraded by the nucleosidases Pnp1 and Urh1, with a minor role for Meu1, and ultimately converted to NAD(+) via the nicotinamidase Pnc1 and the Preiss-Handler pathway. Using C. glabrata mutants whose growth depends exclusively on the external NA or NR supply, we also show that C. glabrata utilizes NR and to a lesser extent NA as NAD(+) sources during disseminated infection.

  9. Triclosan antagonizes fluconazole activity against Candida albicans.

    LENUS (Irish Health Repository)

    Higgins, J

    2012-01-01

    Triclosan is a broad-spectrum antimicrobial compound commonly used in oral hygiene products. Investigation of its activity against Candida albicans showed that triclosan was fungicidal at concentrations of 16 mg\\/L. However, at subinhibitory concentrations (0.5-2 mg\\/L), triclosan antagonized the activity of fluconazole. Although triclosan induced CDR1 expression in C. albicans, antagonism was still observed in cdr1Δ and cdr2Δ strains. Triclosan did not affect fluconazole uptake or alter total membrane sterol content, but did induce the expression of FAS1 and FAS2, indicating that its mode of action may involve inhibition of fatty acid synthesis, as it does in prokaryotes. However, FAS2 mutants did not exhibit increased susceptibility to triclosan, and overexpression of both FAS1 and FAS2 alleles did not alter triclosan susceptibility. Unexpectedly, the antagonistic effect was specific for C. albicans under hypha-inducing conditions and was absent in the non-filamentous efg1Δ strain. This antagonism may be due to the membranotropic activity of triclosan and the unique composition of hyphal membranes.

  10. Candida glabrata Binding to Candida albicans Hyphae Enables Its Development in Oropharyngeal Candidiasis.

    Science.gov (United States)

    Tati, Swetha; Davidow, Peter; McCall, Andrew; Hwang-Wong, Elizabeth; Rojas, Isolde G; Cormack, Brendan; Edgerton, Mira

    2016-03-01

    Pathogenic mechanisms of Candida glabrata in oral candidiasis, especially because of its inability to form hyphae, are understudied. Since both Candida albicans and C. glabrata are frequently co-isolated in oropharyngeal candidiasis (OPC), we examined their co-adhesion in vitro and observed adhesion of C. glabrata only to C. albicans hyphae microscopically. Mice were infected sublingually with C. albicans or C. glabrata individually, or with both species concurrently, to study their ability to cause OPC. Infection with C. glabrata alone resulted in negligible infection of tongues; however, colonization by C. glabrata was increased by co-infection or a pre-established infection with C. albicans. Furthermore, C. glabrata required C. albicans for colonization of tongues, since decreasing C. albicans burden with fluconazole also reduced C. glabrata. C. albicans hyphal wall adhesins Als1 and Als3 were important for in vitro adhesion of C. glabrata and to establish OPC. C. glabrata cell wall protein coding genes EPA8, EPA19, AWP2, AWP7, and CAGL0F00181 were implicated in mediating adhesion to C. albicans hyphae and remarkably, their expression was induced by incubation with germinated C. albicans. Thus, we found a near essential requirement for the presence of C. albicans for both initial colonization and establishment of OPC infection by C. glabrata.

  11. Comparative genomics of the fungal pathogens Candida dubliniensis and Candida albicans.

    LENUS (Irish Health Repository)

    Jackson, Andrew P

    2009-12-01

    Candida dubliniensis is the closest known relative of Candida albicans, the most pathogenic yeast species in humans. However, despite both species sharing many phenotypic characteristics, including the ability to form true hyphae, C. dubliniensis is a significantly less virulent and less versatile pathogen. Therefore, to identify C. albicans-specific genes that may be responsible for an increased capacity to cause disease, we have sequenced the C. dubliniensis genome and compared it with the known C. albicans genome sequence. Although the two genome sequences are highly similar and synteny is conserved throughout, 168 species-specific genes are identified, including some encoding known hyphal-specific virulence factors, such as the aspartyl proteinases Sap4 and Sap5 and the proposed invasin Als3. Among the 115 pseudogenes confirmed in C. dubliniensis are orthologs of several filamentous growth regulator (FGR) genes that also have suspected roles in pathogenesis. However, the principal differences in genomic repertoire concern expansion of the TLO gene family of putative transcription factors and the IFA family of putative transmembrane proteins in C. albicans, which represent novel candidate virulence-associated factors. The results suggest that the recent evolutionary histories of C. albicans and C. dubliniensis are quite different. While gene families instrumental in pathogenesis have been elaborated in C. albicans, C. dubliniensis has lost genomic capacity and key pathogenic functions. This could explain why C. albicans is a more potent pathogen in humans than C. dubliniensis.

  12. Candida spp. in oral cancer and oral precancerous lesions.

    Science.gov (United States)

    Gall, Francesca; Colella, Giuseppe; Di Onofrio, Valeria; Rossiello, Raffaele; Angelillo, Italo Francesco; Liguori, Giorgio

    2013-07-01

    To assess the presence of Candida spp. in lesions of the oral cavity in a sample of patients with precancer or cancer of the mouth and evaluate the limitations and advantages of microbiological and histological methods, 103 subjects with precancerous or cancerous lesions and not treated were observed between 2007 and 2009. The presence of Candida in the lesions was analyzed by microbiological and histological methods. Cohen's k statistic was used to assess the agreement between culture method and staining techniques. Forty-eight (47%) patients had cancer and 55 (53%) patients had precancerous lesions. Candida spp. were isolated from 31 (30%) patients with cancerous lesions and 33 (32%) with precancerous lesions. C. albicans was the most frequent species isolated in the lesions. The k value showed a fair overall agreement for comparisons between culture method and PAS (0.2825) or GMS (0.3112). This study supports the frequent presence of Candida spp. in cancer and precancerous lesions of the oral cavity. Both microbiological investigations and histological techniques were reliable for detection of Candida spp. It would be desirable for the two techniques to be considered complementary in the detection of yeast infections in these types of lesions.

  13. Evaluation of Urinary Tract Infections Due to Candida Species

    Directory of Open Access Journals (Sweden)

    Yeser Karaca Derici

    2016-02-01

    Full Text Available Aim: Although urinary tract infections often caused by bacteria, fungal etiology is detected in a significant number of infections in which Candida is the leading cause. In this study we aimed to evaluate the distribution of Candida strains isolated from urine samples in our hospital. Material and Method: Candida species were identified based on germ tube test, colony morphology on chrom agar Candida (Biomerieux, France and API ID32C AUX (Biomerieux, France commercial kit. Data were analyzed with SPSS 15.0 software for data analysis. Results: During March 2011-March 2014 a total of 109662 urine cultures were evaluated and 24364 samples revealed significant growth. Of the significant growth detected 24364 (22% samples 1096 (4.5% were defined as yeasts. The isolates most frequently detected in this study were C. albicans (50.5%, C. tropicalis (15.9%, C. glabrata (12.7%, C. parapsilosis (7.2%, C. kefyr (5.8%, C. krusei (5.5%. The highest yeast growth was observed in anesthesia intensive care unit. Discussion: In our study, the most frequently isolated species of yeast in the urine was C. albicans. Determination of Candida species and their clinical distributions in hospitals is very important in terms of giving direction to the treatment and measures to be taken.

  14. Inhibitory effect of farnesol on biofilm formation by Candida tropicalis

    Directory of Open Access Journals (Sweden)

    E Zibafar

    2009-03-01

    Full Text Available ABSTRACT Background: Candidiasis associated with indwelling medical devices is especially problematic since they can act as substrates for biofilm growth which are highly resistant to antifungal drugs. Farnesol is a quorum-sensing molecule that inhibits filamentation and biofilm formation in Candida albicans. Since in recent years Candida tropicalis have been reported as an important and common non-albicans Candida species with high drug resistance pattern, the inhibitory effect of farnesol on biofilm formation by Candida tropicalis was evaluated. Methods: Five Candida tropicalis strains were treated with different concentration of farnesol (0, 30 and 300 µM after 0, 1 and 4 hrs of adherence and then they were maintained under biofilm formation condition in polystyrene, 96-well microtiter plates at 37°C for 48 hrs. Biofilm formation was measured by a semiquantitative colorimetric technique based on reduction assay of 2,3- bis  -2H-tetrazolium- 5- carboxanilide (XTT. Results: The results indicated that the initial adherence time had no effect on biofilm formation and low concentration of farnesol (30 µM could not inhibit biofilm formation. However the presence of non-adherent cells increased biofilm formation significantly and the high concentration of farnesol (300 µM could inhibit biofilm formation. Conclusion: Results of this study showed that the high concentration of farnesol could inhibit biofilm formation and may be used as an adjuvant in prevention and in therapeutic strategies with antifungal drugs.

  15. Signs of chronic stress in women with recurrent candida vulvovaginitis.

    Science.gov (United States)

    Ehrström, Sophia M; Kornfeld, Dan; Thuresson, Jessica; Rylander, Eva

    2005-10-01

    The purpose of this study was to determine whether there is an association between recurrent vulvovaginal candida and chronic stress. Chronic stress affects the hypothalamus-pituitary-adrenal axis, which influences the immune function. Recurrent candida vulvovaginitis is increasing. Women with recurrent vulvovaginal candida (n = 35) and age-matched healthy control subjects (n = 35) collected saliva for the analysis of cortisol. Hormone analyses of blood samples and vulvovaginal examinations were performed. A questionnaire was completed. Morning rise cortisol level was significantly blunted among patients compared with control subjects (P vulvovaginal candida, compared with control subjects. More patients than control subjects reported a history of condyloma, bacterial vaginosis, and herpes genitalis. No differences were seen between patients and control subjects regarding sexual hormone binding globulin, dihydroepiandrosterone, testosterone or Hemoglobin A1c. Morning rise salivary cortisol level is blunted in women with recurrent vulvovaginal candida, which indicates signs of chronic stress. The higher incidence of vulvovaginal infections in these women compared with control subjects may reflect impaired immunity, which may be due to chronic stress.

  16. The immune response against Candida spp. and Sporothrix schenckii.

    Science.gov (United States)

    Martínez-Álvarez, José A; Pérez-García, Luis A; Flores-Carreón, Arturo; Mora-Montes, Héctor M

    2014-01-01

    Candida albicans is the main causative agent of systemic candidiasis, a condition with high mortality rates. The study of the interaction between C. albicans and immune system components has been thoroughly studied and nowadays there is a model for the anti-C. albicans immune response; however, little is known about the sensing of other pathogenic species of the Candida genus. Sporothrix schenckii is the causative agent of sporotrichosis, a subcutaneous mycosis, and thus far there is limited information about its interaction with the immune system. In this paper, we review the most recent information about the immune sensing of species from genus Candida and S. schenckii. Thoroughly searches in scientific journal databases were performed, looking for papers addressing either Candida- or Sporothrix-immune system interactions. There is a significant advance in the knowledge of non-C. albicans species of Candida and Sporothrix immune sensing; however, there are still relevant points to address, such as the specific contribution of pathogen-associated molecular patterns (PAMPs) for sensing by different immune cells and the immune receptors involved in such interactions. This manuscript is part of the series of works presented at the "V International Workshop: Molecular genetic approaches to the study of human pathogenic fungi" (Oaxaca, Mexico, 2012). Copyright © 2013 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.

  17. Phospholipase and proteinase activities of Candida spp. isolates from vulvovaginitis in Iran.

    Science.gov (United States)

    Shirkhani, S; Sepahvand, A; Mirzaee, M; Anbari, K

    2016-09-01

    This study aims to characterize phospholipase and proteinase activities of Candida isolates from 82 vulvovaginal candidiasis (VVC) and to study the relationship of these activities with vulvovaginitis. Totally 82 Candida isolates from vagina samples of VVC patients were randomly collected over the period between September and December 2014 from hospitalized patients at the general hospitals of Lorestan province, Iran. Isolates were previously identified by conventional mycological methods. The phospholipase and proteinase activities were evaluated by Egg yolk agar, Tween 80 opacity medium and agar plate methods. The most common Candida species was identified Candida albicans (n=34, 41.5%), followed by Candida famata (n=13, 15.8%), Candida tropicalis (n=11, 13.4%), and Candida parapsilosis (n=9, 11%). The most phospholipase activity was observed in Candida colliculosa (40%), followed by C. famata (38.5%), and Candida krusei (33.3%). The findings revealed that the correlation between phospholipase production by Candida spp. and the presence of VVC was not found to be statistically significant (P=0.91). All Candida spp. exhibited considerable proteinase activity; so that 100% of C. colliculosa, C. parapsilosis, Candida kefyr, and Candida intermedia isolates produced high proteinase activity with Pz 4+ scores. There was a significant correlation between proteinase production by Candida spp. and the presence of VVC (P=0.009). The obtained findings revealed that Candida spp. isolates may produce both virulence factors, phospholipase and proteinase. Although the phospholipase production was only observed in <40% of the isolates; however there was a significant association between proteinase production by Candida spp. and VVC. Copyright © 2016. Published by Elsevier Masson SAS.

  18. Candida species isolated from different body sites and their antifungal susceptibility pattern: Cross-analysis of Candida albicans and Candida glabrata biofilms.

    Science.gov (United States)

    Cataldi, Valentina; Di Campli, Emanuela; Fazii, Paolo; Traini, Tonino; Cellini, Luigina; Di Giulio, Mara

    2017-08-01

    Candida species are regular commensal in humans, but-especially in immunocompromised patients-they represent opportunistic pathogens giving rise to systemic infection. The aim of the present work was to isolate and characterize for their antifungal profile Candida species from different body sites and to analyze the biofilms produced by C. albicans and C. glabrata isolates. Eighty-one strains of Candida species from 77 patients were identified. Epidemiological study showed that the most isolated species were C. albicans (44), C. glabrata (13) and C. parapsilosis (13) mainly from Hematology, Infectious Diseases, Medicine, Neonatology and Oncology Divisions, the majority of the biological samples were swabs (44) and blood cultures (16). The analysis of the biofilm formation was performed at 24 and 48-hours comparing resistant and susceptible strains of C. albicans to resistant and susceptible strains of C. glabrata. Candida albicans has a greater ability to form biofilm compared to C. glabrata, both in the susceptible and resistant strains reaching maturity after 24 hours with a complex structure composed of blastospores, pseudohyphae, and hyphae embedded in a matrix. On the contrary, C. glabrata biofilm was composed exclusively of blastospores that in the resistant strain, after 24 hours, were organized in a compact multilayer different to the discontinuous structure observed in the susceptible analyzed strains. In conclusion, the increasing of the incidence of Candida species infection together with their emerging drug resistance also related to the biofilm forming capability underline the need to monitor their distribution and susceptibility patterns for improving the surveillance and for a correct management of the infection. © The Author 2016. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  19. Prevalence of Candida albicans and carriage of Candida non-albicans in the saliva of preschool children, according to their caries status.

    Science.gov (United States)

    Lozano Moraga, Carla Paola; Rodríguez Martínez, Gonzalo Andrés; Lefimil Puente, Claudia Andrea; Morales Bozo, Irene Cecilia; Urzúa Orellana, Blanca Regina

    2017-01-01

    This study was conducted to establish associations among the Candida carriage rate, the diversity of Candida species carried and the different caries status of preschool children. Sixty-one children between 2 and 5 years of age were examined by a single expert examiner and were divided into three groups, the caries-free, moderate caries and severe caries groups, according to the criteria of the International Caries Detection and Assessment System II (ICDAS). Saliva samples were obtained from the members of each group and were plated on Sabouraud agar plates to assess the Candida carriage rates. CHROMagar Candida medium was used for the preliminary screening. Biochemical testing or PCR/sequencing was conducted to identify the different Candida species in the samples. The differences observed were considered significant if the p value was Candida carriage rate and the number of species of this fungus carried were higher in the group with the highest level of caries severity (p Candida albicans was the most predominant Candida species in the saliva of all of the children, C. dubliniensis was identified only in the most caries-affected group in addition to other rare species of Candida non-albicans. A high salivary Candida carriage rate and the presence of specific species of this fungus (such as C. albicans and C. dubliniensis) appear to be related to the severity of caries experienced by preschool children.

  20. 40 CFR 180.1289 - Candida oleophila Strain O; exemption from the requirement of a tolerance.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Candida oleophila Strain O; exemption... FOOD Exemptions From Tolerances § 180.1289 Candida oleophila Strain O; exemption from the requirement... the microbial pesticide, Candida oleophila Strain O, on apples and pears when applied/used as a post...

  1. In Vitro Antifungal Susceptibility of Oral Candida Isolates from Patients Suffering from Caries and Chronic Periodontitis.

    Science.gov (United States)

    De-la-Torre, Janire; Ortiz-Samperio, María Esther; Marcos-Arias, Cristina; Marichalar-Mendia, Xabier; Eraso, Elena; Echebarria-Goicouria, María Ángeles; Aguirre-Urizar, José Manuel; Quindós, Guillermo

    2017-06-01

    Caries and chronic periodontitis are common oral diseases where a higher Candida colonization is reported. Antifungal agents could be adjuvant drugs for the therapy of both clinical conditions. The aim of the current study has been to evaluate the in vitro activities of conventional and new antifungal drugs against oral Candida isolates from patients suffering from caries and/or chronic periodontitis. In vitro activities of amphotericin B, fluconazole, itraconazole, miconazole, nystatin, posaconazole and voriconazole against 126 oral Candida isolates (75 Candida albicans, 18 Candida parapsilosis, 11 Candida dubliniensis, six Candida guilliermondii, five Candida lipolytica, five Candida glabrata, four Candida tropicalis and two Candida krusei) from 61 patients were tested by the CLSI M27-A3 method. Most antifungal drugs were highly active, and resistance was observed in less than 5% of tested isolates. Miconazole was the most active antifungal drug, being more than 98% of isolates susceptible. Fluconazole, itraconazole, and the new triazoles, posaconazole and voriconazole, were also very active. Miconazole, fluconazole and voriconazole have excellent in vitro activities against all Candida isolates and could represent suitable treatment for a hypothetically adjunctive therapy of caries and chronic periodontitis.

  2. Candida in saliva of Brazilian hemophilic patients Candida na saliva de pacientes hemofílicos brasileiros

    Directory of Open Access Journals (Sweden)

    Claudio Maranhão Pereira

    2004-12-01

    Full Text Available Hemophilia is a common hereditary hemorrhagic disorder, however little is known about the oral microflora of hemophilic patients. The aim of this study was to quantify the Candida and identify its species in non-stimulated saliva of hemophilic patients, and consider its relationship with clinical factors influencing Candida carriage. This study comprised evaluation of 86 hemophilic patients of the Hematology Center/UNICAMP and 43 healthy subjects as controls. All patients were submitted to anamnesis, intraoral examination and unstimulated saliva collection. Candida counts and species identification were performed in salivary samples. Candida was present in 64% of the hemophilic patients and in 44% of the healthy controls. C. albicans represented 65% and 68% of the isolated species, in hemophiliacs and control group respectively, and C. tropicalis was the second most common species in both groups. These results indicate that hemophilic patients carry Candida more frequently and in higher counts than healthy controls, independently of oral clinical parameter considered, as viral infections, complete dentures, transfusions of hemoderivatives, and salivary flow.Hemofilia é uma alteração hemorrágica hereditária comum, entretanto pouco se sabe a respeito da microbiota oral destes indivíduos. O objetivo deste estudo foi quantificar a presença de Candida e identificar as suas espécies na saliva de hemofílicos, correlacionando os resultados com fatores clínicos que possam influenciar a presença deste fungo. Foram avaliados 86 hemofílicos do Hemocentro/UNICAMP e 43 indivíduos saudáveis. Todos os pacientes foram submetidos a anamnese, exame clínico intra-oral e coleta de saliva de forma não estimulada. A quantificação e identificação das espécies de Candida foram realizadas nas amostras de saliva. Candida estava presente em 64% dos hemofílicos e em 44% dos indivíduos saudáveis. C. albicans representou 65% e 68% das esp

  3. Prevalence of candida and non-candida yeasts isolated from patients with yeast fungal infections in Tehran labs

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    Hashemi SJ

    2011-04-01

    Full Text Available "n 800x600 Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} Background: Infections caused by opportunistic yeasts such as Candida species, Trichosporon, Rhodotorula and Saccharomyces have increased in immunocompromis-ed patients and their identification is crucial as intrinsic and acquired resistance of some yeast species to antifungal agents are on the rise. The aim of this study was to identify the organisms to the species level in order to suggest accurate and effective antifungal therapies."n"nMethods: In this study that carried out in Tehran, Iran in 2009, 200 patients with yeast infection were medically examined and clinical specimens were prepared for direct examination and culture on Sabouraud dextrose agar. Subsequently, the isolated yeast colonies were identified using various tests including culture on Corn Meal agar with Tween 80, CHROMagar Candida and casein agar. For the definite identification of organisms some biochemical tests were done based on carbohydrate assimilation by RapID Yeast Plus System kit, and, finally, a molecular method, PCR-RFLP, using Hpa II enzyme, was performed for the remaining unknown yeast species."n"nResults: A total of 211 yeast isolates were identified in 200 patients with yeast infections. The most frequent isolated yeasts were Candida albicans, 124 (58.77%, followed by Candida parapsilosis, 36 (17.06%, Candida tropicalis, 17 (8.06%, Candida glabrata, 13 (6.16%, Candida krusei, 8 (3.79%, Candida guilliermondii, 2 (0.96%, Trichosporon, 3 (1.14%, Rhodotorula, 1 (0.47%, Saccaromyces cerevisiae, 1 (0.47% and other

  4. A case of Candida mediastinitis after dental extraction.

    Science.gov (United States)

    Badiee, Parisa; Alborzi, Abdolvahab; Farhoudi, Farimah

    2011-02-01

    Acute mediastinitis is a serious infection involving the connective mediastinal tissue in the interpleural spaces and other thoracic structures. Candida albicans mediastinitis is a rare clinical entity associated with high mortality and morbidity. We present a rare case of a previously healthy and immunocompetent man with Candida mediastinitis due to retropharyngeal abscess after dental extraction, who presented with odynophagia and fever. Antibiotics were prescribed and surgical drainage was performed after diagnosis of mediastinitis by CT scan; however, the patient remained febrile.  The second culture obtained during irrigation of the mediastinum was positive for Candida albicans and the patient was responsive to antifungal therapy and survived. This case illustrates the need to consider a fungal cause in immunocompetent patients with mediastinitis who are not responsive to broad spectrum antibiotics and surgical drainage.

  5. Vaginal Candida spp. genomes from women with vulvovaginal candidiasis.

    Science.gov (United States)

    Bradford, L Latéy; Chibucos, Marcus C; Ma, Bing; Bruno, Vincent; Ravel, Jacques

    2017-08-31

    Candida albicans is the predominant cause of vulvovaginal candidiasis (VVC). Little is known regarding the genetic diversity of Candida spp. in the vagina or the microvariations in strains over time that may contribute to the development of VVC. This study reports the draft genome sequences of four C. albicans and one C. glabrata strains isolated from women with VVC. An SNP-based whole-genome phylogeny indicates that these isolates are closely related; however, phylogenetic distances between them suggest that there may be genetic adaptations driven by unique host environments. These sequences will facilitate further comparative analyses and ultimately improve our understanding of genetic variation in isolates of Candida spp. that are associated with VVC. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Candida glabrata Biofilms: How Far Have We Come?

    Science.gov (United States)

    Rodrigues, Célia F.; Rodrigues, Maria Elisa; Silva, Sónia; Henriques, Mariana

    2017-01-01

    Infections caused by Candida species have been increasing in the last decades and can result in local or systemic infections, with high morbidity and mortality. After Candida albicans, Candida glabrata is one of the most prevalent pathogenic fungi in humans. In addition to the high antifungal drugs resistance and inability to form hyphae or secret hydrolases, C. glabrata retain many virulence factors that contribute to its extreme aggressiveness and result in a low therapeutic response and serious recurrent candidiasis, particularly biofilm formation ability. For their extraordinary organization, especially regarding the complex structure of the matrix, biofilms are very resistant to antifungal treatments. Thus, new approaches to the treatment of C. glabrata’s biofilms are emerging. In this article, the knowledge available on C. glabrata’s resistance will be highlighted, with a special focus on biofilms, as well as new therapeutic alternatives to control them. PMID:29371530

  7. Candida glabrata Biofilms: How Far Have We Come?

    Directory of Open Access Journals (Sweden)

    Célia F. Rodrigues

    2017-03-01

    Full Text Available Infections caused by Candida species have been increasing in the last decades and can result in local or systemic infections, with high morbidity and mortality. After Candida albicans, Candida glabrata is one of the most prevalent pathogenic fungi in humans. In addition to the high antifungal drugs resistance and inability to form hyphae or secret hydrolases, C. glabrata retain many virulence factors that contribute to its extreme aggressiveness and result in a low therapeutic response and serious recurrent candidiasis, particularly biofilm formation ability. For their extraordinary organization, especially regarding the complex structure of the matrix, biofilms are very resistant to antifungal treatments. Thus, new approaches to the treatment of C. glabrata’s biofilms are emerging. In this article, the knowledge available on C. glabrata’s resistance will be highlighted, with a special focus on biofilms, as well as new therapeutic alternatives to control them.

  8. Mechanisms of antifungal drug resistance in Candida dubliniensis.

    LENUS (Irish Health Repository)

    Coleman, David C

    2010-06-01

    Candida dubliniensis was first described in 1995 and is the most closely related species to the predominant human fungal pathogen Candida albicans. C. dubliniensis is significantly less prevalent and less pathogenic than C. albicans and is primarily associated with infections in HIV-infected individuals and other immunocompromised cohorts. The population structure of C. dubliniensis consists of three well-defined major clades and is significantly less diverse than C. albicans. The majority of C. dubliniensis isolates are susceptible to antifungal drugs commonly used to treat Candida infections. To date only two major patterns of antifungal drug resistance have been identified and the molecular mechanisms of these are very similar to the resistance mechanisms that have been described previously in C. albicans. However, significant differences are evident in the predominant antifungal drug mechanisms employed by C. dubliniensis, differences that reflect its more clonal nature, its lower prevalence and characteristics of its genome, the complete sequence of which has only recently been determined.

  9. Inhibition of d-xylose isomerase by polyols: atomic details by joint X-ray/neutron crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Kovalevsky, Andrey, E-mail: ayk@lanl.gov [Los Alamos National Laboratory, PO Box 1663, MS M888, Los Alamos, NM 87545 (United States); Hanson, B. Leif [University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606 (United States); Mason, Sax A. [Institut Laue–Langevin, 6 Rue Jules Horowitz, 38042 Grenoble (France); Forsyth, V. Trevor [Institut Laue–Langevin, 6 Rue Jules Horowitz, 38042 Grenoble (France); Keele University, Staffordshire (United Kingdom); Fisher, Zoe [Los Alamos National Laboratory, PO Box 1663, MS M888, Los Alamos, NM 87545 (United States); Mustyakimov, Marat [Los Alamos National Laboratory, PO Box 1663, MS M888, Los Alamos, NM 87545 (United States); Oak Ridge National Laboratory, PO Box 2008, MS 6475, Oak Ridge, TN 37831 (United States); Blakeley, Matthew P. [Institut Laue–Langevin, 6 Rue Jules Horowitz, 38042 Grenoble (France); Keen, David A. [Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX (United Kingdom); Langan, Paul [Oak Ridge National Laboratory, PO Box 2008, MS 6475, Oak Ridge, TN 37831 (United States); Los Alamos National Laboratory, PO Box 1663, MS M888, Los Alamos, NM 87545 (United States)

    2012-09-01

    A joint X-ray/neutron structure of d-xylose isomerase in complex with the inhibitor sorbitol was determined at room temperature at an acidic pH of 5.9. Protonation of the O5 O atom of the sugar was directly observed in the nuclear density maps. Under acidic conditions sorbitol gains a water-mediated interaction with the enzyme active site, which may explain the increased potency of the inhibitor at low pH. d-Xylose isomerase (XI) converts the aldo-sugars xylose and glucose to their keto analogs xylulose and fructose, but is strongly inhibited by the polyols xylitol and sorbitol, especially at acidic pH. In order to understand the atomic details of polyol binding to the XI active site, a 2.0 Å resolution room-temperature joint X-ray/neutron structure of XI in complex with Ni{sup 2+} cofactors and sorbitol inhibitor at pH 5.9 and a room-temperature X-ray structure of XI containing Mg{sup 2+} ions and xylitol at the physiological pH of 7.7 were obtained. The protonation of oxygen O5 of the inhibitor, which was found to be deprotonated and negatively charged in previous structures of XI complexed with linear glucose and xylulose, was directly observed. The Ni{sup 2+} ions occupying the catalytic metal site (M2) were found at two locations, while Mg{sup 2+} in M2 is very mobile and has a high B factor. Under acidic conditions sorbitol gains a water-mediated interaction that connects its O1 hydroxyl to Asp257. This contact is not found in structures at basic pH. The new interaction that is formed may improve the binding of the inhibitor, providing an explanation for the increased affinity of the polyols for XI at low pH.

  10. Comparative genomic and transcriptomic analysis revealed genetic characteristics related to solvent formation and xylose utilization in Clostridium acetobutylicum EA 2018

    Directory of Open Access Journals (Sweden)

    Wang Shengyue

    2011-02-01

    Full Text Available Abstract Background Clostridium acetobutylicum, a gram-positive and spore-forming anaerobe, is a major strain for the fermentative production of acetone, butanol and ethanol. But a previously isolated hyper-butanol producing strain C. acetobutylicum EA 2018 does not produce spores and has greater capability of solvent production, especially for butanol, than the type strain C. acetobutylicum ATCC 824. Results Complete genome of C. acetobutylicum EA 2018 was sequenced using Roche 454 pyrosequencing. Genomic comparison with ATCC 824 identified many variations which may contribute to the hyper-butanol producing characteristics in the EA 2018 strain, including a total of 46 deletion sites and 26 insertion sites. In addition, transcriptomic profiling of gene expression in EA 2018 relative to that of ATCC824 revealed expression-level changes of several key genes related to solvent formation. For example, spo0A and adhEII have higher expression level, and most of the acid formation related genes have lower expression level in EA 2018. Interestingly, the results also showed that the variation in CEA_G2622 (CAC2613 in ATCC 824, a putative transcriptional regulator involved in xylose utilization, might accelerate utilization of substrate xylose. Conclusions Comparative analysis of C. acetobutylicum hyper-butanol producing strain EA 2018 and type strain ATCC 824 at both genomic and transcriptomic levels, for the first time, provides molecular-level understanding of non-sporulation, higher solvent production and enhanced xylose utilization in the mutant EA 2018. The information could be valuable for further genetic modification of C. acetobutylicum for more effective butanol production.

  11. Ecdysteroids in Sida tuberculata R.E. Fries (Malvaceae): chemical composition by LC-ESI-MS and selective anti-Candida krusei activity.

    Science.gov (United States)

    da Rosa, Hemerson Silva; de Camargo, Vanessa Brum; Camargo, Graziela; Garcia, Cássia V; Fuentefria, Alexandre M; Mendez, Andreas S L

    2015-09-01

    Sida tuberculata is found in a region of South America and has traditionally been consumed as an infusion or tea. The chemical composition and antifungal activity of aqueous infusions from leaves and roots were investigated. LC-ESI-MS mass spectra were successfully obtained and used to identify four ecdysteroids: 20-hydroxyecdysone-3-O-β-D-glycopyranoside, 20-hydroxyecdysone, 20-hydroxyecdysone-3-O-β-D-xylose and a hydroxyecdysterone derivative. The in vitro antifungal activity was studied, and the minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) were established against Candida krusei isolates. The antibiofilm activity was evaluated by the determination of the biofilm removal efficiency in contaminated central venous catheter (CVC) coupons. The preparations exhibited antifungal activity against the species tested, with MICs ranging from 3.90 to 62.50 μg/ml. The infusion removed the C. krusei biofilm after 90 min of exposure. The observed bioactivity and composition of ecdysteroids will contribute to the future development of antifungal substances for clinical use or as food additives. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Reclassification of Candida guilliermondii FTI 20037 as Candida tropicalis based on molecular phylogenetic analysis Reclassificação de Candida guilliermondii FTI 20037 como Candida tropicalis baseada na análise filogenética molecular

    Directory of Open Access Journals (Sweden)

    Luanne Helena Augusto Lima

    2003-11-01

    Full Text Available Yeasts of the genus Candida are of clinical importance and also have many industrial applications, mainly in the food industry. The yeast Candida guilliermondii FTI 20037 has been extensively studied in order to establish a biotechnological process for the production of xylitol. The goal of this study was to verify the taxonomic classification of this strain based on the analysis of rDNA sequences and the xyl1 gene. DNA fragments from these sequences were amplified by PCR and BLAST analysis revealed strong identity with the corresponding sequences from Candida tropicalis. Based on these results, we propose that C. guilliermondii FTI 20037 must be reclassified as C. tropicalis.As leveduras do gênero Candida possuem tanto importância clínica como diversas aplicações industriais, principalmente na indústria de alimentos. A levedura Candida guilliermondii FTI 20037 tem sido exaustivamente estudada pois pretende-se utilizá-la no estabelecimento de um processo biotecnológico para a produção de xilitol. O objetivo deste trabalho foi verificar a classificação taxonômica desta levedura por análise de sequências do rDNA e do gene xyl1. Fragmentos correspondentes a estas regiões foram amplificados por PCR e a análise destas sequências por BLAST revelou alta identidade com sequências correspondentes de Candida tropicalis. Estes resultados nos levam a propor que C. guilliermondii FTI 20037 deva ser reclassificada como C. tropicalis.

  13. SAXS-WAXS studies of the low-resolution structure in solution of xylose/glucose isomerase from Streptomyces rubiginosus

    Science.gov (United States)

    Kozak, Maciej; Taube, Michał

    2009-10-01

    The structure and conformation of molecule of xylose/glucose isomerase from Streptomyces rubiginosus in solution (at pH 6 and 7.6; with and without the substrate) has been studied by small- and wide-angle scattering of synchrotron radiation (SAXS-WAXS). On the basis of the SAXS-WAXS data, the low-resolution structure in solution has been reconstructed using ab inito methods. A comparison of the models of glucose isomerase shows only small differences between the model in solution and the crystal structure.

  14. Pretreatments and enzymatic hydrolysis of sugarcane bagasse aiming at the enhancement of the yield of glucose and xylose

    Directory of Open Access Journals (Sweden)

    A. de A. Guilherme

    Full Text Available ABSTRACT This work studied the enzymatic hydrolysis of sugarcane bagasse aiming at the production of glucose and xylose. The bagasse was subjected to two different pretreatments: combined acid and alkalinepretreatment and hydrogen peroxidepretreatment. The enzymatic hydrolysis was optimized and a kinetic study was carried out in a stirred tank reactor (STR in batch mode. Optimal conditions were obtained by subjecting the bagasse to the hydrogen peroxide pretreatment followed by enzymatic hydrolysis. The addition of xylanases to the enzymatic mixture improved the production of fermentable sugars by 48%.

  15. Impact of zinc supplementation on the improved fructose/xylose utilization and butanol production during acetone-butanol-ethanol fermentation.

    Science.gov (United States)

    Wu, You-Duo; Xue, Chuang; Chen, Li-Jie; Bai, Feng-Wu

    2016-01-01

    Lignocellulosic biomass and dedicated energy crops such as Jerusalem artichoke are promising alternatives for biobutanol production by solventogenic clostridia. However, fermentable sugars such as fructose or xylose released from the hydrolysis of these feedstocks were subjected to the incomplete utilization by the strains, leading to relatively low butanol production and productivity. When 0.001 g/L ZnSO4·7H2O was supplemented into the medium containing fructose as sole carbon source, 12.8 g/L of butanol was achieved with butanol productivity of 0.089 g/L/h compared to only 4.5 g/L of butanol produced with butanol productivity of 0.028 g/L/h in the control without zinc supplementation. Micronutrient zinc also led to the improved butanol production up to 8.3 g/L derived from 45.2 g/L xylose as sole carbon source with increasing butanol productivity by 31.7%. Moreover, the decreased acids production was observed under the zinc supplementation condition, resulting in the increased butanol yields of 0.202 g/g-fructose and 0.184 g/g-xylose, respectively. Similar improvements were also observed with increasing butanol production by 130.2 % and 8.5 %, butanol productivity by 203.4% and 18.4%, respectively, in acetone-butanol-ethanol fermentations from sugar mixtures of fructose/glucose (4:1) and xylose/glucose (1:2) simulating the hydrolysates of Jerusalem artichoke tubers and corn stover. The results obtained from transcriptional analysis revealed that zinc may have regulatory mechanisms for the sugar transport and metabolism of Clostridium acetobutylicum L7. Therefore, micronutrient zinc supplementation could be an effective way for economic development of butanol production derived from these low-cost agricultural feedstocks. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  16. Separation of xylose and glucose using an integrated membrane system for enzymatic cofactor regeneration and downstream purification

    DEFF Research Database (Denmark)

    Morthensen, Sofie Thage; Sigurdardóttir, Sigyn Björk; Meyer, Anne S.

    2017-01-01

    Mixtures of xylose, glucose and pyruvate were fed to a membrane bioreactor equipped with a charged NF membrane (NTR 7450). Value-added products were obtained in the reactor via enzymatic cofactor-dependent catalysis of glucose to gluconic acid and pyruvate to lactic acid, respectively. The initial...... cofactor (NADH) concentration could be decreased to 10% of the stoichiometric value (relative to glucose) without compromising process time and substrate conversion via i) efficient cofactor regeneration and ii) high retention of cofactor (R=0.98) in the membrane bioreactor. Furthermore, accumulation...

  17. Candida parapsilosis in domestic laundry machines.

    Science.gov (United States)

    Dögen, Aylin; Sav, Hafize; Gonca, Serpil; Kaplan, Engin; Ilkit, Macit; Novak Babic, Monika; Gunde-Cimerman, Nina; de Hoog, G Sybren

    2017-11-01

    Candida parapsilosis, although a human commensal, acts as an opportunistic pathogen associated with nosocomial infections, with a rising incidence worldwide. Its ecological characteristics are poorly understood. Human-made environments within dwellings, such as dishwashers and water distribution systems, represent major sources of fungi such as C. parapsilosis. Here, we investigated the presence of members of the C. parapsilosis complex in 99 washing machines in various dwellings in the city of Mersin, Turkey. We sampled three sites in each washing machine: (i) the washing powder drawers, (ii) fabric softener drawers, and (iii) rubber seals around the washing machine doors. Additionally, we recorded the type of cleanser used by each customer. Of note, 25.3% of sampled washing machines harbored C. parapsilosis strains, later identified as the members of the C. parapsilosis sensu stricto via internal transcribed spacer (ITS) sequencing. Out of the 29 isolates obtained, biofilm-forming ability and proteinase and esterase activities were recorded in 14, 11, and 4 of the isolates, respectively. Our results suggest that the washing machines investigated abundantly harbored C. parapsilosis sensu stricto; however, no single preferred isolation site or association with cleanser type was observed (P > .05). Furthermore, C. parapsilosis isolates grew at temperatures ranging from 10°C to 37°C, at pH values ranging from 4 to 10, and were found to tolerate 5-10% NaCl. Domestic laundry appliances as a potential source of C. parapsilosis infections are discussed. © The Author 2017. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Candida glabrata um patogénio emergente?

    OpenAIRE

    Matilde, Filipa Alexandra Veiga

    2014-01-01

    Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz Nas últimas décadas as infecções fúngicas têm aumentado exponencialmente. Apesar de Candida albicans (C. albicans) continuar a ser a espécie isolada com maior frequência, as espécies não albicans tem vindo a proliferar rapidamente. Candida glabrata (C. glabrata) é uma das espécies emergentes como patogénio oportunista humano, sendo responsável maioritariamente por candidoses invasivas em pacie...

  19. Sucessfull management of bilateral presumed Candida endogenous endophtalmitis following pancreatitis

    Directory of Open Access Journals (Sweden)

    Ricardo Evangelista Marrocos de Aragão

    2016-06-01

    Full Text Available ABSTRACT Endogenous endophthalmitis is a rare, and frequently devastating, ophthalmic disease. It occurs mostly in immunocompromised patients, or those with diabetes mellitus, cancer or intravenous drugs users. Candida infection is the most common cause of endogenous endophthalmitis. Ocular candidiasis develops within days to weeks of fungemia. The association of treatment for pancreatitis with endophthalmitis is unusual. Treatment with broad-spectrum antibiotics and total parenteral nutrition may explain endogenous endophthalmitis. We report the case of a patient with pancreatitis treated with broad-spectrum antibiotics and total parenteral nutrition who developed bilateral presumed Candida endogenous endophthalmitis that was successfully treated with vitrectomy and intravitreal amphotericin B.

  20. Hexosomes with Undecylenic Acid Efficient against Candida albicans

    OpenAIRE

    Marijana Mionić Ebersold; Milica Petrović; Wye-Khay Fong; Debora Bonvin; Heinrich Hofmann; Irena Milošević

    2018-01-01

    Due to the growing issues with fungal infections, especially with Candida, there is still a need to develop novel anti-Candida materials. One of the known antifungal agents is undecylenic acid (UA), which still cannot be efficiently used due to its oily nature, and thus limited solubility. By taking advantage of the properties of UA, we developed an emulsion with hexagonal phase, i.e., hexosomes, whose structure and morphology was studied by small-angle X-ray scattering and cryo-electron micr...