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Sample records for kluyveromyces marxianus imb3

  1. The use of a thermotolerant fermentative Kluyveromyces marxianus IMB3 yeast strain for ethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Banat, I.M. [Univ. of the United Arab Emirates, Al-Ain (United Arab Emirates). Dept. of Biolology; Singh, D. [Haryana Agriculture Univ., Hisar (India). Dept. of Microbiology; Marchant, R. [Ulster Univ. (United Kingdom). School of Applied Biological and Chemical Sciences

    1996-12-31

    An investigation was carried out on the growth and ethanol production of a novel thermotolerant ethanol-producing Kluyveromyces marxianus IMB3 yeast strain. It grew aerobically on glucose, lactose, cellobiose, xylose and whey permeate and fermented all the above carbon sources to ethanol at 45 C. This strain was capable of growing under anaerobic chemostat fermentation conditions at 45 C and a dilution rate of 0.15 h{sup -1} and produced {<=}0.9 g/l biomass and 1.8% (v/v) ethanol. An increase in biomass (up to 10.0 g/l) and ethanol (up to 4.3% v/v at 45 C and 7.7% v/v at 40 C) were achieved by applying a continuous two-stage fermentation in sequence (one aerobic and one anerobic stage) or a two-stage anaerobic fermentation with cell recycling. Potential applications, involving alcohol production systems, for use in dairy and wood related industries, were discussed. (orig.)

  2. Ethanol production by Kluyveromyces marxianus IMB3 during growth on straw-supplemented whiskey distillery spent wash at 45 C

    Energy Technology Data Exchange (ETDEWEB)

    Barron, N.; Mulholland, H.; Boyle, M.; McHale, A.P. [Biotechnology Research Group, School of Applied Biological and Chemical Sciences, University of Ulster, Coleraine, Co. Londonderry, BT52 1SA (United Kingdom)

    1997-11-01

    The thermotolerant, ethanol-producing yeast strain, Kluyveromyces marxianus IMB3 was grown on media consisting of straw-supplemented distillery spent wash from The Old Bushmill`s Distillery Co. Ltd., Bushmills, Co Antrim, Northern Ireland. Media were supplemented with cellulase activity and fermentations were carried out at 45 C. When pulverized straw was used as substrate in this system at concentrations of 2, 4 and 6% (w/v), ethanol concentrations increased to maxima of 1.45, 2.2 and 3 g/l, respectively. Based on straw containing a maximum of 40% cellulose, these ethanol concentrations accounted for 36, 27 and 24% of the maximum theoretical yield, respectively. When the straw was pre-treated with NaOH and used in the spent wash containing system at concentrations of 2, 4 and 6% (w/v) ethanol, concentrations increased to maxima of 3, 6.2 and 10.5 g/l, respectively and these accounted for 75, 76 and 86% of the maximum theoretical yield. When these results are compared with previously published data relating to the use of straw in laboratory-based media, they suggest that whiskey distillery spent wash may provide an adequate medium for supplementation with complex carbohydrate and subsequent ethanol production in simultaneous saccharification and fermentation processes. (orig.) With 2 figs., 17 refs.

  3. Sucrose-supplemented distillery spent wash as a medium for production of ethanol at 45 C by free and alginate-immobilized preparations of Kluyveromyces marxianus IMB3

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, P.; Mulholland, H.; Barron, N.; Brady, D.; McHale, A.P. [Biotechnology Research Group, School of Applied Biological and Chemical Sciences, University of Ulster (United Kingdom)

    1998-04-01

    Ethanol production by the thermotolerant, ethanol-producing yeast strain Kluyveromyces marxianus IMB3, was compared during growth on sucrose-supplemented laboratory-based media and distillery spent wash from the Old Bushmill`s Distillery Co., Ltd., Co. Antrim, Northern Ireland. Fermentations were carried out using preparations of the free and alginate-immobilized microorganism as inocula in media supplemented with 2 and 10% (w/v) sucrose. Maximum ethanol concentrations accounted for 75-99% of the maximum theoretical yield and in all cases maximum concentrations obtained using the spent wash were similar if not slightly higher than those obtained on the sucrose-supplemented yeast growth media. In addition, the highest concentrations of ethanol were produced by the alginate-immobilized biocatalyst on both types of media. Analysis of exhausted media in the spent wash-based systems demonstrated significant decreases in the total organic carbon content following fermentation. These results confirm our earlier suggestion that ethanol production based on this microorganism in a recycle system may provide a more cost-effective means of disposing of whiskey distillery spent wash. (orig.) With 1 tab., 8 refs.

  4. Production of yeast extract from whey using Kluyveromyces marxianus

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    Revillion Jean P. de Palma

    2003-01-01

    Full Text Available The yeast Kluyveromyces marxianus CBS 6556 was grown on whey to produce nucleotide-rich yeast extracts. Thermal treatments of cells at 35 or 50ºC for 15-30h resulted in yeast extracts containing about 20 g/L protein, with only the second treatment resulting in the presence of small amounts of RNA. In contrast, autolysis in buffered solution was the unique treatment that resulted in release of high amounts of intracellular RNA, being, therefore, the better procedure to produce 5'-nucletide rich extract with K. marxianus.

  5. Kluyveromyces marxianus as a host for heterologous protein synthesis.

    Science.gov (United States)

    Gombert, Andreas K; Madeira, José Valdo; Cerdán, María-Esperanza; González-Siso, María-Isabel

    2016-07-01

    The preferentially respiring and thermotolerant yeast Kluyveromyces marxianus is an emerging host for heterologous protein synthesis, surpassing the traditional preferentially fermenting yeast Saccharomyces cerevisiae in some important aspects: K . marxianus can grow at temperatures 10 °C higher than S. cerevisiae, which may result in decreased costs for cooling bioreactors and reduced contamination risk; has ability to metabolize a wider variety of sugars, such as lactose and xylose; is the fastest growing eukaryote described so far; and does not require special cultivation techniques (such as fed-batch) to avoid fermentative metabolism. All these advantages exist together with a high secretory capacity, performance of eukaryotic post-translational modifications, and with a generally regarded as safe (GRAS) status. In the last years, replication origins from several Kluyveromyces spp. have been used for the construction of episomal vectors, and also integrative strategies have been developed based on the tendency for non-homologous recombination displayed by K. marxianus. The recessive URA3 auxotrophic marker and the dominant Kan(R) are mostly used for selection of transformed cells, but other markers have been made available. Homologous and heterologous promoters and secretion signals have been characterized, with the K. marxianus INU1 expression and secretion system being of remarkable functionality. The efficient synthesis of roughly 50 heterologous proteins has been demonstrated, including one thermophilic enzyme. In this mini-review, we summarize the physiological characteristics of K. marxianus relevant for its use in the efficient synthesis of heterologous proteins, the efforts performed hitherto in the development of a molecular toolbox for this purpose, and some successful examples.

  6. Ethanol production from paper sludge using Kluyveromyces marxianus

    International Nuclear Information System (INIS)

    Madrid, Lina Maria; Quintero Diaz, Juan Carlos

    2011-01-01

    Recycled paper sludge is a promising raw material for ethanol production. In this study, we first evaluated the effects of ethanol concentration, solids load, and cellulose crystallinity on the enzymatic hydrolysis of cellulose to produce reducing sugars. We then evaluated the production of ethanol by either saccharification and simultaneous fermentation (SSF) or separated hydrolysis and fermentation (SHF) using the yeast Kluyveromyces marxianus ATCC 36907. We found that cellulose hydrolysis decreased as ethanol concentrations increased; at 40 g/L ethanol, the reducing sugar production was decreased by 79 %. Hydrolysis also decreased as solids load increased; at 9 % of solids, the cellulose conversion was 76 % of the stoichiometric production. The ethanol yield and cellulose conversion rate were higher with SSF as opposed to SHF processes at 72 h of treatment.

  7. OPTIMIZATION OF INULINASE PRODUCTION USING COPRA WASTE BY Kluyveromyces marxianus var. marxianus

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    M. DILIPKUMAR

    2010-12-01

    Full Text Available Kluyveromyces marxianus var. marxianus was found to secrete a large amount of extracellular inulinase in to the medium. The optimization of inulinase pro¬duction using copra waste as a carbon source was performed with statistical methodology based on experimental designs. The screening of eighteen nut¬rients for their influence on inulinase production was achieved using a Plackett––Burman design. Corn steep liquor, (NH42SO4, ZnSO47H2O, K2HPO4 and urea were selected based on their positive influence on inulinase production. The selected components were optimized using response surface methodology (RSM. The optimum conditions are: corn steep liquor – 0.0560 (g/gds, (NH42SO4 – 0.0084 (g/gds, ZnSO47H2O – 0.0254 (g/gds, K2HPO4 – 0.0037 (g/gds and urea - 0.02147 (g/gds. These conditions were validated experimentally which revealed an enhanced inulinase yield of 372 U/gds.

  8. Synthesis of Fructooligosaccharides from Sucrose Using Inulinase from Kluyveromyces marxianus

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    Francisco Maugeri

    2007-01-01

    Full Text Available Fructooligosaccharides (FOS from sucrose, new alternative sweeteners with functional properties, also called soluble fibers, have a number of desirable characteristics such as low calories, no cariogenicity, and safety for diabetics and Bifidus stimulating factor. Fructooligosaccharides are also known as prebiotics, since they stimulate probiotic organisms. The production, as well as the application of food-grade fructooligosaccharides, has increased rapidly during last years. In this work, experimental factorial design has been applied to optimize the fructooligosaccharide synthesis conditions by inulinase from Kluyveromyces marxianus var. bulgaricus. The studied variables were: temperature, pH, sucrose and enzyme concentrations. According to the results, only temperature and sucrose concentrations have shown to be significant parameters. The syntheses of the fructooligosaccharides were carried out on stirred reactor and packed bed reactors, using free and immobilized enzymes, with the best conditions obtained from the experimental design. It has been shown that there is no significant difference between these processes. The final sugar concentrations can be tailor made by varying residence time in the reactor to cope with the different standard needs in food industries. A typical solution product consists of a mixture of fructose (155 g/L, glucose (155 g/L, sucrose (132 g/L and fructooligosaccharides (50 g/L. These concentrations are suitable for applications in most food industries, in products such as sweets, candies, chocolates and yogurts. Besides, the prebiotic function of fructooligosaccharides as stimulants of the beneficial intestinal flora will give the product a functional and differentiated feature.

  9. Uranium removal from acidic aqueous solutions by Saccharomyces cerevisiae, Debaryomyces hansenii, Kluyveromyces marxianus and Candida colliculosa

    International Nuclear Information System (INIS)

    Sarri, S.; Misaelides, P.; Papanikolaou, M.; Zamboulis, D.

    2009-01-01

    The sorption of uranium from acidic aqueous solutions (pH 4.5, C init = 10 to 1000 mg U/L) by Saccharomyces cerevisiae, Debaryomyces hansenii, Kluyveromyces marxianus and Candida colliculosa was investigated using a batch technique. The U-sorption onto Saccharomyces cerevisiae and Debaryomyces hansenii followed a Langmuir, while that onto Kluyveromyces marxianus and Candida colliculosa a Freundlich isotherm. The results demonstrated that all investigated biomasses could effectively remove uranium from acidic aqueous solutions. From all sorbents, Saccharomyces cerevisiae appeared to be the most effective with a maximum sorption capacity of 127.7 mg U/g dry biomass. (author)

  10. Improved ethanol production from whey Saccharomyces cerevisiae using permeabilized cells of Kluyveromyces marxianus

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, M [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology; Tomaska, M [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology; Kanuch, J [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology; Sturdik, E [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology

    1996-12-31

    Permeabilized cells of Kluyveromyces marxianus CCY eSY2 were tested as the source of lactase in the ethanol fermentation of concentrated deproteinized whey (65-70 g/l lactose) by Saccharomyces cerevisiae CCY 10-13-14. Rapid lactose hydrolysis by small amounts of permeabilized cells following the fermentation of released glucose and galactose by S. cerevisiae resulted in a twofold enhancement of the overall volumetric productivity (1.03 g/lxh), compared to the fermentation in which the lactose was directly fermented by K. marxianus. (orig.)

  11. Production of bioethanol from organic whey using Kluyveromyces marxianus

    DEFF Research Database (Denmark)

    Christensen, A.D.; Kádár, Zsófia; Oleskowicz-Popiel, Piotr

    2011-01-01

    Ethanol production by K. marxianus in whey from organic cheese production was examined in batch and continuous mode. The results showed that no pasteurization or freezing of the whey was necessary and that K. marxianus was able to compete with the lactic acid bacteria added during cheese production...... ethanol yield (~0.50 g ethanol/g lactose) at both 30°C and 40°C using low pH (4.5) or no pH control. Continuous fermentation of nonsterilized whey was performed using Ca-alginate-immobilized K. marxianus. High ethanol productivity (2.5-4.5 g/l/h) was achieved at dilution rate of 0.2/h......, and it was concluded that K. marxianus is very suitable for industrial ethanol production from whey. © 2010 Society for Industrial Microbiology....

  12. Transcriptome analysis of the thermotolerant yeast Kluyveromyces marxianus CCT 7735 under ethanol stress.

    Science.gov (United States)

    Diniz, Raphael Hermano Santos; Villada, Juan C; Alvim, Mariana Caroline Tocantins; Vidigal, Pedro Marcus Pereira; Vieira, Nívea Moreira; Lamas-Maceiras, Mónica; Cerdán, María Esperanza; González-Siso, María-Isabel; Lahtvee, Petri-Jaan; da Silveira, Wendel Batista

    2017-09-01

    The thermotolerant yeast Kluyveromyces marxianus displays a potential to be used for ethanol production from both whey and lignocellulosic biomass at elevated temperatures, which is highly alluring to reduce the cost of the bioprocess. Nevertheless, contrary to Saccharomyces cerevisiae, K. marxianus cannot tolerate high ethanol concentrations. We report the transcriptional profile alterations in K. marxianus under ethanol stress in order to gain insights about mechanisms involved with ethanol response. Time-dependent changes have been characterized under the exposure of 6% ethanol and compared with the unstressed cells prior to the ethanol addition. Our results reveal that the metabolic flow through the central metabolic pathways is impaired under the applied ethanol stress. Consistent with these results, we also observe that genes involved with ribosome biogenesis are downregulated and gene-encoding heat shock proteins are upregulated. Remarkably, the expression of some gene-encoding enzymes related to unsaturated fatty acid and ergosterol biosynthesis decreases upon ethanol exposure, and free fatty acid and ergosterol measurements demonstrate that their content in K. marxianus does not change under this stress. These results are in contrast to the increase previously reported with S. cerevisiae subjected to ethanol stress and suggest that the restructuration of K. marxianus membrane composition differs in the two yeasts which gives important clues to understand the low ethanol tolerance of K. marxianus compared to S. cerevisiae.

  13. Performance evaluation of Pichia kluyveri, Kluyveromyces marxianus and Saccharomyces cerevisiae in industrial tequila fermentation.

    Science.gov (United States)

    Amaya-Delgado, L; Herrera-López, E J; Arrizon, Javier; Arellano-Plaza, M; Gschaedler, A

    2013-05-01

    Traditionally, industrial tequila production has used spontaneous fermentation or Saccharomyces cerevisiae yeast strains. Despite the potential of non-Saccharomyces strains for alcoholic fermentation, few studies have been performed at industrial level with these yeasts. Therefore, in this work, Agave tequilana juice was fermented at an industrial level using two non-Saccharomyces yeasts (Pichia kluyveri and Kluyveromyces marxianus) with fermentation efficiency higher than 85 %. Pichia kluyveri (GRO3) was more efficient for alcohol and ethyl lactate production than S. cerevisiae (AR5), while Kluyveromyces marxianus (GRO6) produced more isobutanol and ethyl-acetate than S. cerevisiae (AR5). The level of volatile compounds at the end of fermentation was compared with the tequila standard regulation. All volatile compounds were within the allowed range except for methanol, which was higher for S. cerevisiae (AR5) and K. marxianus (GRO6). The variations in methanol may have been caused by the Agave tequilana used for the tests, since this compound is not synthesized by these yeasts.

  14. Producción de inulinasa por levaduras de Kluyveromyces marxianus

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    Augusto Castillo Calderón

    2010-01-01

    Full Text Available En este trabajo se han revisado los principales avances alcanzados en los últimos veinte años, en el estudio de la fermentación de cepas de Kluyveromyces marxianus para la producción de la enzima inulinasa a partir de inulina pura y fuentes de inulina y la determinación de las propiedades y características de la enzima. Con el propósito de recopilar y esclarecer el mayor conocimiento de ésta área, la investigación de ésta materia ha sido dividida en tres partes: sustratos fuentes de inulina; producción microbiana de inulinasa y caracterización y propiedades de la inulinasa. Se discute la información existente sobre los microorganismos capaces de producir inulinasa los que han sido publicados con datos de rendimiento y en particular las condiciones de fermentación de cepas de Klu yveromyces marxianus para la producción de inulinasa a partir de varias fuentes vegetales de inulina. Se concluye que si bien es cierto existen cepas de Kluyveromyces marxianus capaces de producir satisfactoriamente inulinasa, la investigación para una fuente vegetal de inulina económicamente interesante todavía está en curso.

  15. Opuntia ficus-indica cladodes as feedstock for ethanol production by Kluyveromyces marxianus and Saccharomyces cerevisiae.

    Science.gov (United States)

    Kuloyo, Olukayode O; du Preez, James C; García-Aparicio, Maria del Prado; Kilian, Stephanus G; Steyn, Laurinda; Görgens, Johann

    2014-12-01

    The feasibility of ethanol production using an enzymatic hydrolysate of pretreated cladodes of Opuntia ficus-indica (prickly pear cactus) as carbohydrate feedstock was investigated, including a comprehensive chemical analysis of the cladode biomass and the effects of limited aeration on the fermentation profiles and sugar utilization. The low xylose and negligible mannose content of the cladode biomass used in this study suggested that the hemicellulose structure of the O. ficus-indica cladode was atypical of hardwood or softwood hemicelluloses. Separate hydrolysis and fermentation and simultaneous saccharification and fermentation procedures using Kluyveromyces marxianus and Saccharomyces cerevisiae at 40 and 35 °C, respectively, gave similar ethanol yields under non-aerated conditions. In oxygen-limited cultures K. marxianus exhibited almost double the ethanol productivity compared to non-aerated cultures, although after sugar depletion utilization of the produced ethanol was evident. Ethanol concentrations of up to 19.5 and 20.6 g l(-1) were obtained with K. marxianus and S. cerevisiae, respectively, representing 66 and 70 % of the theoretical yield on total sugars in the hydrolysate. Because of the low xylan content of the cladode biomass, a yeast capable of xylose fermentation might not be a prerequisite for ethanol production. K. marxianus, therefore, has potential as an alternative to S. cerevisiae for bioethanol production. However, the relatively low concentration of fermentable sugars in the O. ficus-indica cladode hydrolysate presents a technical constraint for commercial exploitation.

  16. 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.

  17. 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.

  18. Effect of Sugar Concentration in Jerusalem Artichoke Extract on Kluyveromyces marxianus Growth and Ethanol Production

    OpenAIRE

    Margaritis, Argyrios; Bajpai, Pratima

    1983-01-01

    The effect of inulin sugars concentration on the growth and ethanol production by Kluyveromyces marxianus UCD (FST) 55-82 was studied. A maximum ethanol concentration of 102 g/liter was obtained from 250 g of sugars per liter initial concentration. The maximum specific growth rate varied from 0.44 h−1 at 50 g of sugar per liter to 0.13 h−1 at 300 g of sugar per liter, whereas the ethanol yield remained almost constant at 0.45 g of ethanol per g of sugars utilized.

  19. Ethanol Production from Whey by Kluyveromyces marxianus in Batch Fermentation System: Kinetics Parameters Estimation

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    Dessy Ariyanti

    2013-03-01

    Full Text Available Whey is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. In environmental point of view, whey is kind of waste which has high pollution level due to it’s contain high organic compound with BOD and COD value 50 and 80 g/L respectively. On the other side, whey also contain an amount of lactose (4.5%-5%; lactose can be used as carbon source and raw material for producing ethanol via fermentation using yeast strain Kluyveromyces marxianus. The objective of this research is to investigate the ethanol production kinetics from crude whey through fermentation using Kluyveromyces marxianus and to predict the model kinetics parameter. The yeast was able to metabolize most of the lactose within 16 h to give 8.64 g/L ethanol, 4.43 g/L biomass, and remain the 3.122 g/L residual lactose. From the results presented it also can be concluded that common kinetic model for microbial growth, substrate consumption, and product formation is a good alternative to describe an experimental batch fermentation of Kluyveromyces marxianus grown on a medium composed of whey. The model was found to be capable of reflecting all batch culture phases to a certain degree of accuracy, giving the parameter value: μmax, Ks, YX/S, α, β : 0.32, 10.52, 0.095, 1.52, and 0.11 respectively. © 2013 BCREC UNDIP. All rights reserved(Selected Paper from International Conference on Chemical and Material Engineering (ICCME 2012Received: 27th September 2012; Revised: 29th November 2012; Accepted: 7th December 2012[How to Cite: D. Ariyanti, H. Hadiyanto, (2013. Ethanol Production from Whey by Kluyveromyces marxianus in Batch Fermentation System: Kinetics Parameters Estimation. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 179-184. (doi:10.9767/bcrec.7.3.4044.179-184][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4044.179-184 ] View in  |

  20. Ploidy Variation in Kluyveromyces marxianus Separates Dairy and Non-dairy Isolates

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    Raúl A. Ortiz-Merino

    2018-03-01

    Full Text Available Kluyveromyces marxianus is traditionally associated with fermented dairy products, but can also be isolated from diverse non-dairy environments. Because of thermotolerance, rapid growth and other traits, many different strains are being developed for food and industrial applications but there is, as yet, little understanding of the genetic diversity or population genetics of this species. K. marxianus shows a high level of phenotypic variation but the only phenotype that has been clearly linked to a genetic polymorphism is lactose utilisation, which is controlled by variation in the LAC12 gene. The genomes of several strains have been sequenced in recent years and, in this study, we sequenced a further nine strains from different origins. Analysis of the Single Nucleotide Polymorphisms (SNPs in 14 strains was carried out to examine genome structure and genetic diversity. SNP diversity in K. marxianus is relatively high, with up to 3% DNA sequence divergence between alleles. It was found that the isolates include haploid, diploid, and triploid strains, as shown by both SNP analysis and flow cytometry. Diploids and triploids contain long genomic tracts showing loss of heterozygosity (LOH. All six isolates from dairy environments were diploid or triploid, whereas 6 out 7 isolates from non-dairy environment were haploid. This also correlated with the presence of functional LAC12 alleles only in dairy haplotypes. The diploids were hybrids between a non-dairy and a dairy haplotype, whereas triploids included three copies of a dairy haplotype.

  1. Respiratory capacity of the Kluyveromyces marxianus yeast isolated from the mezcal process during oxidative stress.

    Science.gov (United States)

    Arellano-Plaza, Melchor; Gschaedler-Mathis, Anne; Noriega-Cisneros, Ruth; Clemente-Guerrero, Mónica; Manzo-Ávalos, Salvador; González-Hernández, Juan Carlos; Saavedra-Molina, Alfredo

    2013-07-01

    During the mezcal fermentation process, yeasts are affected by several stresses that can affect their fermentation capability. These stresses, such as thermal shock, ethanol, osmotic and growth inhibitors are common during fermentation. Cells have improved metabolic systems and they express stress response genes in order to decrease the damage caused during the stress, but to the best of our knowledge, there are no published works exploring the effect of oxidants and prooxidants, such as H2O2 and menadione, during growth. In this article, we describe the behavior of Kluyveromyces marxianus isolated from spontaneous mezcal fermentation during oxidative stress, and compared it with that of Saccharomyces cerevisiae strains that were also obtained from mezcal, using the W303-1A strain as a reference. S. cerevisiae strains showed greater viability after oxidative stress compared with K. marxianus strains. However, when the yeast strains were grown in the presence of oxidants in the media, K. marxianus exhibited a greater ability to grow in menadione than it did in H2O2. Moreover, when K. marxianus SLP1 was grown in a minibioreactor, its behavior when exposed to menadione was different from its behavior with H2O2. The yeast maintained the ability to consume dissolved oxygen during the 4 h subsequent to the addition of menadione, and then stopped respiration. When exposed to H2O2, the yeast stopped consuming oxygen for the following 8 h, but began to consume oxygen when stressors were no longer applied. In conclusion, yeast isolated from spontaneous mezcal fermentation was able to resist oxidative stress for a long period of time.

  2. Simultaneous saccharification and fermentation of Agave tequilana fructans by Kluyveromyces marxianus yeasts for bioethanol and tequila production.

    Science.gov (United States)

    Flores, Jose-Axel; Gschaedler, Anne; Amaya-Delgado, Lorena; Herrera-López, Enrique J; Arellano, Melchor; Arrizon, Javier

    2013-10-01

    Agave tequilana fructans (ATF) constitute a substrate for bioethanol and tequila industries. As Kluyveromyces marxianus produces specific fructanases for ATF hydrolysis, as well as ethanol, it can perform simultaneous saccharification and fermentation. In this work, fifteen K. marxianus yeasts were evaluated to develop inoculums with fructanase activity on ATF. These inoculums were added to an ATF medium for simultaneous saccharification and fermentation. All the yeasts, showed exo-fructanhydrolase activity with different substrate specificities. The yeast with highest fructanase activity in the inoculums showed the lowest ethanol production level (20 g/l). Five K. marxianus strains were the most suitable for the simultaneous saccharification and fermentation of ATF. The volatile compounds composition was evaluated at the end of fermentation, and a high diversity was observed between yeasts, nevertheless all of them produced high levels of isobutyl alcohol. The simultaneous saccharification and fermentation of ATF with K. marxianus strains has potential for industrial application. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Automated UV-C mutagenesis of Kluyveromyces marxianus NRRL Y-1109 and selection for microaerophilic growth and ethanol production at elevated temperature on biomass sugars

    Science.gov (United States)

    The yeast Kluyveromyces marxianus is a potential microbial catalyst for producing ethanol from lignocellulosic substrates at elevated temperatures. To improve its growth and ethanol yield under anaerobic conditions, K. marxianus NRRL Y-1109 was irradiated with UV-C, and surviving cells were grown a...

  4. Cashew apple bagasse as a source of sugars for ethanol production by Kluyveromyces marxianus CE025.

    Science.gov (United States)

    Rocha, Maria Valderez Ponte; Rodrigues, Tigressa Helena Soares; Melo, Vania M M; Gonçalves, Luciana R B; de Macedo, Gorete Ribeiro

    2011-08-01

    The potential of cashew apple bagasse as a source of sugars for ethanol production by Kluyveromyces marxianus CE025 was evaluated in this work. This strain was preliminarily cultivated in a synthetic medium containing glucose and xylose and was able to produce ethanol and xylitol at pH 4.5. Next, cashew apple bagasse hydrolysate (CABH) was prepared by a diluted sulfuric acid pretreatment and used as fermentation media. This hydrolysate is rich in glucose, xylose, and arabinose and contains traces of formic acid and acetic acid. In batch fermentations of CABH at pH 4.5, the strain produced only ethanol. The effects of temperature on the kinetic parameters of ethanol fermentation by K. marxianus CE025 using CABH were also evaluated. Maximum specific growth rate (μ(max)), overall yields of ethanol based on glucose consumption [Formula: see text] and based on glucose + xylose consumption (Y ( P/S )), overall yield of ethanol based on biomass (Y ( P/X )), and ethanol productivity (P (E)) were determined as a function of temperature. Best results of ethanol production were achieved at 30°C, which is also quite close to the optimum temperature for the formation of biomass. The process yielded 12.36 ± 0.06 g l(-1) of ethanol with a volumetric production rate of 0.257 ± 0.002 g l(-1) h(-1) and an ethanol yield of 0.417 ± 0.003 g g(-1) glucose.

  5. 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.

  6. Improving xylitol production at elevated temperature with engineered Kluyveromyces marxianus through over-expressing transporters.

    Science.gov (United States)

    Zhang, Jia; Zhang, Biao; Wang, Dongmei; Gao, Xiaolian; Hong, Jiong

    2015-01-01

    Three transporter genes including Kluyveromyces marxianus aquaglyceroporin gene (KmFPS1), Candida intermedia glucose/xylose facilitator gene (CiGXF1) or glucose/xylose symporter gene (CiGXS1) were over-expressed in K. marxianus YZJ017 to improve xylitol production at elevated temperatures. The xylitol production of YZJ074 that harbored CiGXF1 was improved to 147.62g/L in Erlenmeyer flask at 42°C. In fermenter, 99.29 and 149.60g/L xylitol were produced from 99.55 and 151.91g/L xylose with productivity of 4.14 and 3.40g/L/h respectively at 42°C. Even at 45°C, YZJ074 could produce 101.30g/L xylitol from 101.41g/L xylose with productivity of 2.81g/L/h. Using fed-batch fermentation through repeatedly adding non-sterilized substrate directly, YZJ074 could produce 312.05g/L xylitol which is the highest yield reported to date. The engineered strains YZJ074 which can produce xylitol at elevated temperatures is an excellent foundation for xylitol bioconversion. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Acquisition of the yeast Kluyveromyces marxianus from unpasteurised milk by a kefir grain enhances kefir quality.

    Science.gov (United States)

    Gethins, Loughlin; Rea, Mary C; Stanton, Catherine; Ross, R Paul; Kilcawley, Kieran; O'Sullivan, Maurice; Crotty, Suzanne; Morrissey, John P

    2016-08-01

    Kefir is a fermented milk beverage consumed for nutritional and health tonic benefits in many parts of the world. It is produced by the fermentation of milk with a consortium of bacteria and yeast embedded within a polysaccharide matrix. This consortium is not well defined and can vary substantially between kefir grains. There are little data on the microbial stability of kefir grains, nor on interactions between microbes in the grain and in the milk. To study this, a grain was split, with one half of each stored at -20°C and the other half passaged repeatedly in whole unpasteurised milk. Grains passaged in the unpasteurised milk recovered vigour and acquired the yeast Kluyveromyces marxainus from the milk which was confirmed to be the same strain by molecular typing. Furthermore, these passaged grains produced kefir that was distinguished chemically and organoleptically from the stored grains. Some changes in ultrastructure were also observed by scanning electron microscopy. The study showed that kefir grains can acquire yeast from their environment and the final product can be influenced by these newly acquired yeasts. Kluyveromyces marxianus is considered to be responsible for some of the most important characteristics of kefir so the finding that this yeast is part of the less stable microbiota is significant. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Ethanol production using whole plant biomass of Jerusalem artichoke by Kluyveromyces marxianus CBS1555.

    Science.gov (United States)

    Kim, Seonghun; Park, Jang Min; Kim, Chul Ho

    2013-03-01

    Jerusalem artichoke is a low-requirement sugar crop containing cellulose and hemicellulose in the stalk and a high content of inulin in the tuber. However, the lignocellulosic component in Jerusalem artichoke stalk reduces the fermentability of the whole plant for efficient bioethanol production. In this study, Jerusalem artichoke stalk was pretreated sequentially with dilute acid and alkali, and then hydrolyzed enzymatically. During enzymatic hydrolysis, approximately 88 % of the glucan and xylan were converted to glucose and xylose, respectively. Batch and fed-batch simultaneous saccharification and fermentation of both pretreated stalk and tuber by Kluyveromyces marxianus CBS1555 were effectively performed, yielding 29.1 and 70.2 g/L ethanol, respectively. In fed-batch fermentation, ethanol productivity was 0.255 g ethanol per gram of dry Jerusalem artichoke biomass, or 0.361 g ethanol per gram of glucose, with a 0.924 g/L/h ethanol productivity. These results show that combining the tuber and the stalk hydrolysate is a useful strategy for whole biomass utilization in effective bioethanol fermentation from Jerusalem artichoke.

  9. Continuous ethanol production from Jerusalem artichokes stalks using immobilized cells of Kluyveromyces marxianus

    Energy Technology Data Exchange (ETDEWEB)

    Bajpai, P.; Margaritis, A.

    1986-01-01

    Continuous production of ethanol from the extract of Jerusalem artichoke stalks was investigated in a packed bed bioreactor using Kluyveromyces marxianus cells immobilized in calcium alginate gel beds. Maximum conversion of the sugars to ethanol was achieved with a yield of about 98% of the theoretical. Volumetric ethanol productivities of 102 grams of ethanol per litre per hour and 92 grams ethanol per liter per hour were obtained at 87% and 90% conversion respectively for an inlet substrate concentration of 100 gram sugars per liter. The maximum specific ethanol production rate and maximum specific total sugar uptake rate of the immobilized cells were found to be 0.96 gram ethanol per gram immobilized cells per hour and 2.06 gram sugars per gram immobilized cells per hour respectively. The immobilized cell bioreactor was run continuously at a dilution rate of 2.12 per hour for 30 days which resulted in a loss of 30% of the original activity. The half life of the bioreactor was estimated to be about 56 days.

  10. Polygalacturonase and ethanol production in Kluyveromyces marxianus: potential use of polygalacturonase in foodstuffs.

    Science.gov (United States)

    Serrat, Manuel; Bermúdez, Rosa C; Villa, Tomás G

    2004-04-01

    The coproduction of ethanol and polygalacturonase (PG) in a pilot-scale batch fermentor using yeast extract--glucose (YD)--and sugar beet molasses (SBM)-based media was implemented utilizing a new high-PG-producing strain of Kluyveromyces marxianus. A certain growth inhibition was observed in SBM medium, causing ethanol and PG production to be lower. Ethanol productivity and accumulation values of 1.94 g/(L x h) and 40 g/L, respectively, were attained in YD, whereas the best fermentation efficiency (95.1%) was achieved with SBM medium. Maximal PG synthesis occurred at the end of cell growth, with values of 1.08 and 0.46 U/(mg x h) for the YD and SBM media, respectively. When the cultures reached stationary phase, PG production stopped. The highest accumulation level (17 U/mL) occurred in YD medium, in agreement with previous laboratory-scale studies carried out for this strain. The potential applications of the crude enzyme preparations were evaluated with different fruit juices and vegetable slices. The enzyme was able to increase the filtration rate of orange, pear, and apple juices by twofold. Additionally, complete clarification of apple juice was readily accomplished, whereas cucumber, carrot, and banana tissues were macerated to a lesser extent. Copyright 2004 Humana Press Inc.

  11. Production of Bioethanol from Carrot Pomace Using the Thermotolerant Yeast Kluyveromyces marxianus

    Energy Technology Data Exchange (ETDEWEB)

    Chi-Yang Yu; Bo-Hong Jiang; Kow-Jen Duan [Tatung University, Tapei, Taiwan (China). Department of Bioengineering

    2013-03-15

    Carrot pomace, a major agricultural waste from the juice industry, was used as a feedstock for bioethanol production by fermentation with the thermotolerant yeast Kluyveromyces marxianus. Treatment of the carrot pomace with Accellerase(TM) 1000 and pectinase at 50 °C for 84 h, resulted in conversion of 42% of its mass to fermentable sugars, mainly glucose, fructose, and sucrose. Simultaneous saccharification and fermentation (SSF) at 42 °C was performed on 10% (w/v) carrot pomace; the concentration of ethanol reached 18 g/L and the yield of ethanol from carrot pomace was 0.18 g/g. The highest ethanol concentration of 37 g/L was observed with an additional charge of 10% supplemented to the original 10% of carrot pomace after 12 h; the corresponding yield was 0.185 g/g. Our results clearly demonstrated the potential of combining a SSF process with thermotolerant yeast for the production of bioethanol using carrot pomace as a feedstock.

  12. 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.

  13. Thermotolerant Kluyveromyces marxianus and Saccharomyces cerevisiae strains representing potentials for bioethanol production from Jerusalem artichoke by consolidated bioprocessing.

    Science.gov (United States)

    Hu, Nan; Yuan, Bo; Sun, Juan; Wang, Shi-An; Li, Fu-Li

    2012-09-01

    Thermotolerant inulin-utilizing yeast strains are desirable for ethanol production from Jerusalem artichoke tubers by consolidated bioprocessing (CBP). To obtain such strains, 21 naturally occurring yeast strains isolated by using an enrichment method and 65 previously isolated Saccharomyces cerevisiae strains were investigated in inulin utilization, extracellular inulinase activity, and ethanol fermentation from inulin and Jerusalem artichoke tuber flour at 40 °C. The strains Kluyveromyces marxianus PT-1 (CGMCC AS2.4515) and S. cerevisiae JZ1C (CGMCC AS2.3878) presented the highest extracellular inulinase activity and ethanol yield in this study. The highest ethanol concentration in Jerusalem artichoke tuber flour fermentation (200 g L(-1)) at 40 °C achieved by K. marxianus PT-1 and S. cerevisiae JZ1C was 73.6 and 65.2 g L(-1), which corresponded to the theoretical ethanol yield of 90.0 and 79.7 %, respectively. In the range of 30 to 40 °C, temperature did not have a significant effect on ethanol production for both strains. This study displayed the distinctive superiority of K. marxianus PT-1 and S. cerevisiae JZ1C in the thermotolerance and utilization of inulin-type oligosaccharides reserved in Jerusalem artichoke tubers. It is proposed that both K. marxianus and S. cerevisiae have considerable potential in ethanol production from Jerusalem artichoke tubers by a high temperature CBP.

  14. Ethanol fermentation with Kluyveromyces marxianus from Jerusalem artichoke grown in salina and irrigated with a mixture of seawater and freshwater.

    Science.gov (United States)

    Yuan, W J; Zhao, X Q; Ge, X M; Bai, F W

    2008-12-01

    To study fuel ethanol fermentation with Kluyveromyces marxianus ATCC8554 from Jerusalem artichoke (Helianthus tuberosus) grown in salina and irrigated with a mixture of seawater and freshwater. The growth and ethanol fermentation of K. marxianus ATCC8554 were studied using inulin as substrate. The activity of inulinase, which attributes to the hydrolysis of inulin, the main carbohydrate in Jerusalem artichoke, was monitored. The optimum temperatures were 38 degrees C for growth and inulinase production, and 35 degrees C for ethanol fermentation. Aeration was not necessary for ethanol fermentation with the K. marxianus from inulin. Then, the fresh Jerusalem artichoke tubers grown in salina and irrigated with 25% and 50% seawater were further examined for ethanol fermentation with the K. marxianus, and a higher ethanol yield was achieved for the Jerusalem artichoke tuber irrigated with 25% seawater. Furthermore, the dry meal of the Jerusalem artichoke tubers irrigated with 25% seawater was examined for ethanol fermentation at three solid concentrations of 200, 225 and 250 g l(-1), and the highest ethanol yield of 0.467, or 91.5% of the theoretical value of 0.511, was achieved for the slurry with a solid concentration of 200 g l(-1). Halophilic Jerusalem artichoke can be used for fuel ethanol production. Halophilic Jerusalem artichoke, not competing with grain crops for arable land, is a sustainable feedstock for fuel ethanol production.

  15. Thermotolerant Kluyveromyces marxianus and Saccharomyces cerevisiae strains representing potentials for bioethanol production from Jerusalem artichoke by consolidated bioprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Nan [Agricultural Univ., Qingdao, SD (China). College of Animal Science and Technology; Chinese Academy of Sciences, Qingdao, SD (China). Key Lab. of Biofuels; Yuan, Bo; Wang, Shi-An; Li, Fu-Li [Chinese Academy of Sciences, Qingdao, SD (China). Key Lab. of Biofuels; Sun, Juan [Agricultural Univ., Qingdao, SD (China). College of Animal Science and Technology

    2012-09-15

    Thermotolerant inulin-utilizing yeast strains are desirable for ethanol production from Jerusalem artichoke tubers by consolidated bioprocessing (CBP). To obtain such strains, 21 naturally occurring yeast strains isolated by using an enrichment method and 65 previously isolated Saccharomyces cerevisiae strains were investigated in inulin utilization, extracellular inulinase activity, and ethanol fermentation from inulin and Jerusalem artichoke tuber flour at 40 C. The strains Kluyveromyces marxianus PT-1 (CGMCC AS2.4515) and S. cerevisiae JZ1C (CGMCC AS2.3878) presented the highest extracellular inulinase activity and ethanol yield in this study. The highest ethanol concentration in Jerusalem artichoke tuber flour fermentation (200 g L{sup -1}) at 40 C achieved by K. marxianus PT-1 and S. cerevisiae JZ1C was 73.6 and 65.2 g L{sup -1}, which corresponded to the theoretical ethanol yield of 90.0 and 79.7 %, respectively. In the range of 30 to 40 C, temperature did not have a significant effect on ethanol production for both strains. This study displayed the distinctive superiority of K. marxianus PT-1 and S. cerevisiae JZ1C in the thermotolerance and utilization of inulin-type oligosaccharides reserved in Jerusalem artichoke tubers. It is proposed that both K. marxianus and S. cerevisiae have considerable potential in ethanol production from Jerusalem artichoke tubers by a high temperature CBP. (orig.)

  16. Influence of carbon and nitrogen source on production of volatile fragrance and flavour metabolites by the yeast Kluyveromyces marxianus.

    Science.gov (United States)

    Gethins, Loughlin; Guneser, Onur; Demirkol, Aslı; Rea, Mary C; Stanton, Catherine; Ross, R Paul; Yuceer, Yonca; Morrissey, John P

    2015-01-01

    The yeast Kluyveromyces marxianus produces a range of volatile molecules with applications as fragrances or flavours. The purpose of this study was to establish how nutritional conditions influence the production of these metabolites. Four strains were grown on synthetic media, using a variety of carbon and nitrogen sources and volatile metabolites analysed using gas chromatography-mass spectrometry (GC-MS). The nitrogen source had pronounced effects on metabolite production: levels of the fusel alcohols 2-phenylethanol and isoamyl alcohol were highest when yeast extract was the nitrogen source, and ammonium had a strong repressing effect on production of 2-phenylethyl acetate. In contrast, the nitrogen source did not affect production of isoamyl acetate or ethyl acetate, indicating that more than one alcohol acetyl transferase activity is present in K. marxianus. Production of all acetate esters was low when cells were growing on lactose (as opposed to glucose or fructose), with a lower intracellular pool of acetyl CoA being one explanation for this observation. Bioinformatic and phylogenetic analysis of the known yeast alcohol acetyl transferases ATF1 and ATF2 suggests that the ancestral protein Atf2p may not be involved in synthesis of volatile acetate esters in K. marxianus, and raises interesting questions as to what other genes encode this activity in non-Saccharomyces yeasts. Identification of all the genes involved in ester synthesis will be important for development of the K. marxianus platform for flavour and fragrance production. Copyright © 2014 John Wiley & Sons, Ltd.

  17. Production of ethanol at high temperatures in the fermentation of Jerusalem artichoke juice and a simple medium by Kluyveromyces marxianus

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, M.F.; Correia, I.S.; Novais, J.M.

    1987-01-01

    Temperatures as high as 36 degrees C and 40 degrees C did not negatively affect the ethanol productivity of Jerusalem artichoke (J.a.) juice batch fermentation and the final concentrations of ethanol were close to those produced at lower temperatures. At higher process temperatures (36-40 degrees C), ethanol toxicity in Kluyveromyces marxianus was less important during the fermentation of J.a. juice as compared with a simple medium. In simple medium, the heat-sticking of fermentation was observed and the percentage of unfermented sugars steeply increased from 28 degrees C up to 40 degrees C. (Refs. 13).

  18. Antioxidant, ACE-Inhibitory and antibacterial activities of Kluyveromyces marxianus protein hydrolysates and their peptide fractions

    Directory of Open Access Journals (Sweden)

    Mahta Mirzaeia

    2016-07-01

    Full Text Available Background: There has been evidence that proteins are potentially excellent source of antioxidants, antihypertensive and antimicrobial peptides, and that enzymatic hydrolysis is an effective method to release these peptides from protein molecules. The functional properties of protein hydrolysates depends on the protein substrate, the specificity of the enzymes, the conditions used during proteolysis, degree of hydrolysis, and the nature of peptides released including molecular weight, amino acid composition, and hydrophobicity. Context and purpose of this study: The biomass of Kluyveromyces marxianus was considered as a source of ACE inhibitory, antioxidant and antimicrobial peptides. Results: Autolysis and enzymatic hydrolysis were completed respectively, after 96 h and 5 h. Overall, trypsin (18.52% DH and chymotrypsin (21.59% DH treatments were successful in releasing antioxidant and ACE inhibitory peptides. Autolysate sample (39.51% DH demonstrated poor antioxidant and ACE inhibitory activity compared to trypsin and chymotrypsin hydrolysates. The chymotrypsin 3-5 kDa (301.6±22.81 μM TE/mg protein and trypsin < 3 kDa (280.16±39.16 μM TE/mg protein permeate peptide fractions showed the highest DPPH radical scavenging activity. The trypsin <3 kDa permeate peptide fraction showed the highest ABTS radical scavenging (1691.1±48.68 μM TE/mg protein and ACE inhibitory (IC50=0.03±0.001 mg/mL activities. The fraction (MW=5-10 kD obtained after autolysis treatment showed antibacterial activity against St. aureus and Lis. monocytogenes in well diffusion screening. The minimum inhibitory concentration (MIC value was 13.3 mg/mLagainst St. aureus and Lis. monocytogenes calculated by turbidimetric assay and it showed bactericidal activity against St. aureus at 21.3 mg/mL protein concentration. Conclusions: Altogether, the results of this study reveal that K. marxianus proteins contain specific peptides in their sequences which can be released by

  19. Hyperproduction and Thermal Characterization of a Novel Invertase from a Double Mutant Derivative of Kluyveromyces marxianus

    Directory of Open Access Journals (Sweden)

    Muhammad Ibrahim Rajoka

    2011-01-01

    Full Text Available Kinetics of intracellular invertase production employing a double mutant derivative of Kluyveromyces marxianus was optimized by varying different process variables in a 23-litre fermentor. The maximum volumetric rate (QP and invertase yield (YP/S by M15 mutant were 1222 U/(L·h and 160 U/g of substrate utilized, respectively (2-fold more than those of parental strain at 50 °C on the molasses (150 g/L of total fermentable sugars at pH=5.5. Glucose or sucrose (100, 150 or 170 g/L did not repress invertase catabolically under the optimized fermentation conditions, contrary to the previous reports on other yeasts and filamentous fungi, where catabolite repression of sugars was predominant. Invertases derived by the wild (IW and mutant (IM strains were purified employing ammonium sulphate precipitation, and then characterized by column chromatographic techniques both kinetically and thermodynamically. The acidic limb of invertases was missing and collation of pKa and the heat of ionization values indicated that carboxyl groups were involved in proton transfer during active catalysis. Ratios of Kcat/Km and vmax/Km indicated that IM was significantly more specific for sucrose hydrolysis. The IM exhibited stability in different buffers at pH=3.0–10.0 and temperature of 50–70 °C, as reflected by long half-lives. IM showed significantly lower values of enthalpy of activation (ΔH* and entropy of activation (ΔS*, while Gibbs free energy (ΔG* was significantly increased at higher temperatures, making the IM thermodynamically more thermostable. Thus IM could be used as a catabolite-resistant invertase for the production of fructose syrup or high gravity ethanol.

  20. UV-C mutagenesis of Kluyveromyces marxianus NRRL Y-1109 strain for improved anaerobic growth at elevated temperature on pentose and hexose sugars

    Science.gov (United States)

    More robust industrial yeast strains from Kluyveromyces marxianus NRRL Y-1109 and have been produced using UV-C irradiation specifically for anaerobic conversion of lignocellulosic sugar streams to fuel ethanol at elevated temperature (45°C). This type of random mutagenesis offers the possibility o...

  1. Fermentation of cacao (Theobroma cacao L.) seeds with a hybrid Kluyveromyces marxianus strain improved product quality attributes.

    Science.gov (United States)

    Leal, Gildemberg Amorim; Gomes, Luiz Humberto; Efraim, Priscilla; de Almeida Tavares, Flavio Cesar; Figueira, Antonio

    2008-08-01

    Fermentation of Theobroma cacao (cacao) seeds is an absolute requirement for the full development of chocolate flavor precursors. An adequate aeration of the fermenting cacao seed mass is a fundamental prerequisite for a satisfactory fermentation. Here, we evaluated whether a controlled inoculation of cacao seed fermentation using a Kluyveromyces marxianus hybrid yeast strain, with an increased pectinolytic activity, would improve an earlier liquid drainage ('sweatings') from the fermentation mass, developing a superior final product quality. Inoculation with K. marxianus increased by one third the volume of drained liquid and affected the microorganism population structure during fermentation, which was detectable up to the end of the process. Introduction of the hybrid yeast affected the profile of total seed protein degradation evaluated by polyacrylamide gel electrophoresis, with improved seed protein degradation, and reduction of titrable acidity. Sensorial evaluation of the chocolate obtained from beans fermented with the K. marxianus inoculation was more accepted by analysts in comparison with the one from cocoa obtained through natural fermentation. The increase in mass aeration during the first 24 h seemed to be fundamental for the improvement of fermentation quality, demonstrating the potential application of this improved hybrid yeast strain with superior exogenous pectinolytic activity.

  2. Purification and substrate specificities of a fructanase from Kluyveromyces marxianus isolated from the fermentation process of Mezcal.

    Science.gov (United States)

    Arrizon, Javier; Morel, Sandrine; Gschaedler, Anne; Monsan, Pierre

    2011-02-01

    A fructanase, produced by a Kluyveromyces marxianus strain isolated during the fermentation step of the elaboration process of "Mezcal de Guerrero" was purified and biochemically characterized. The active protein was a glycosylated dimer with a molecular weight of approximately 250 kDa. The specific enzymatic activity of the protein was determined for different substrates: sucrose, inulin, Agave tequilana fructan, levan and Actilight® and compared with the activity of Fructozyme®. The hydrolysis profile of the different substrates analyzed by HPAEC-PAD showed that the enzyme has different affinities over the substrates tested with a sucrose/inulin enzymatic activity ratio (S/I) of 125. For the hydrolysis of Agave tequilana fructans, the enzyme also showed a higher enzymatic activity and specificity than Fructozyme®, which is important for its potential application in the tequila industry. Copyright © 2010 Elsevier Ltd. All rights reserved.

  3. The influence of molasses addition on the kinetics of alcoholic fermentation of whey using Kluyveromyces marxianus yeast

    Directory of Open Access Journals (Sweden)

    Damir Stanzer

    2004-01-01

    Full Text Available Kinetics of alcoholic fermentation by yeast Kluyveromyces marxianusZIM 75 in various media based on whey and molasses were monitored. The fermentations were performed under static and semiaerobic conditions at 34°C. Deproteinized whey and molasses were mixed in various proportions to give final sugar mass concentrations of 5%, 10% and 15% in medium. The experiments conducted showed that medium with 10 % of sugar (sucrose:lactose=1:1 is optimal for alcoholic fermentations in static and semiaerobic conditions. The best ethanol yield after 24 hours of fermentation was 4.05 % (V/V in static conditions and 4.9 % (V/V in semiaerobic conditions. The biomass yield was 7.78 g d.m./L in semiaerobic conditions and 3.19 g d.m./L in static conditions.

  4. Mathematical modeling of Kluyveromyces marxianus growth in solid-state fermentation using a packed-bed bioreactor.

    Science.gov (United States)

    Mazutti, Marcio A; Zabot, Giovani; Boni, Gabriela; Skovronski, Aline; de Oliveira, Débora; Di Luccio, Marco; Rodrigues, Maria Isabel; Maugeri, Francisco; Treichel, Helen

    2010-04-01

    This work investigated the growth of Kluyveromyces marxianus NRRL Y-7571 in solid-state fermentation in a medium composed of sugarcane bagasse, molasses, corn steep liquor and soybean meal within a packed-bed bioreactor. Seven experimental runs were carried out to evaluate the effects of flow rate and inlet air temperature on the following microbial rates: cell mass production, total reducing sugar and oxygen consumption, carbon dioxide and ethanol production, metabolic heat and water generation. A mathematical model based on an artificial neural network was developed to predict the above-mentioned microbial rates as a function of the fermentation time, initial total reducing sugar concentration, inlet and outlet air temperatures. The results showed that the microbial rates were temperature dependent for the range 27-50 degrees C. The proposed model efficiently predicted the microbial rates, indicating that the neural network approach could be used to simulate the microbial growth in SSF.

  5. Ethanol fermentation by the thermotolerant yeast, Kluyveromyces marxianus TISTR5925, of extracted sap from old oil palm trunk

    Directory of Open Access Journals (Sweden)

    Yoshinori Murata

    2015-05-01

    Full Text Available Palm sap extracted from old oil palm trunks was previously found to contain sugar and nutrients (amino acids and vitamins. Some palm saps contain a low content of sugar due to differences in species or in plant physiology. Here we condensed palm sap with a low content of sugar using flat membrane filtration, then fermented the condensed palm sap at high temperature using the thermotolerant, high ethanol-producing yeast, Kluyveromyces marxianus. Ethanol production under non-optimum conditions was evaluated. Furthermore, the energy required to concentrate the palm sap, and the amount of energy that could be generated from the ethanol, was calculated. The condensation of sugar in sap from palm trunk required for economically viable ethanol production was evaluated.

  6. Production of antioxidant and ACE-inhibitory peptides from Kluyveromyces marxianus protein hydrolysates: Purification and molecular docking

    Directory of Open Access Journals (Sweden)

    Mahta Mirzaei

    2018-04-01

    Full Text Available Kluyveromyces marxianus protein hydrolysates were prepared by two different sonicated-enzymatic (trypsin and chymotrypsin hydrolysis treatments to obtain antioxidant and ACE-inhibitory peptides. Trypsin and chymotrypsin hydrolysates obtained by 5 h, exhibited the highest antioxidant and ACE-inhibitory activities. After fractionation using ultrafiltration and reverse phase high performance liquid chromatography (RP-HPLC techniques, two new peptides were identified. One fragment (LL-9, MW = 1180 Da with the amino acid sequence of Leu-Pro-Glu-Ser-Val-His-Leu-Asp-Lys showed significant ACE inhibitory activity (IC50 = 22.88 μM while another peptide fragment (VL-9, MW = 1118 Da with the amino acid sequence of Val-Leu-Ser-Thr-Ser-Phe-Pro-Pro-Lys showed the highest antioxidant and ACE inhibitory properties (IC50 = 15.20 μM, 5568 μM TE/mg protein. The molecular docking studies revealed that the ACE inhibitory activities of VL-9 is due to interaction with the S2 (His513, His353, Glu281 and S′1 (Glu162 pockets of ACE and LL-9 can fit perfectly into the S1 (Thr345 and S2 (Tyr520, Lys511, Gln281 pockets of ACE. Keywords: K. marxianus, Bioactive peptides, Antioxidant, ACE inhibitory, Protein hydrolysate

  7. Optimization of the production of extracellular α-amylase by Kluyveromyces marxianus IF0 0288 by response surface methodology

    Directory of Open Access Journals (Sweden)

    Panagiota-Yiolanda Stergiou

    2014-06-01

    Full Text Available The aim of this work was to study the production of extracellular α-amylase by Kluyveromyces marxianus IF0 0288 using optimized nutritional and cultural conditions in a complex yeast medium under aerobic batch fermentation. By applying the conventional "one-variable-at-a-time" approach and the response surface methodology, the effect of four fermentation parameters (type of carbon source, initial culture pH, temperature, and incubation time on the growth and α-amylase production was evaluated. The production of α-amylase during 60 h of fermentation increased 13-fold under optimized conditions (1% starch, pH 6.0, 30ºC in comparison to the conventional optimization method. The initial pH value of 6.13 and temperature of 30.3ºC were optimal conditions by the response surface methodology, leading to further improvement (up to 13-fold in the production of extracellular α-amylase. These results constituted first evidence that K. marxianus could be potentially used as an effective source of extracellular α-amylase.

  8. Direct ethanol production from cellulosic materials at high temperature using the thermotolerant yeast Kluyveromyces marxianus displaying cellulolytic enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Yanase, Shuhei; Yamada, Ryosuke; Ogino, Chiaki; Kondo, Akihiko [Kobe Univ. (Japan). Dept. of Chemical Science and Engineering; Hasunuma, Tomohisa; Tanaka, Tsutomu; Fukuda, Hideki [Kobe Univ. (Japan). Organization of Advanced Science and Technology

    2010-09-15

    To exploit cellulosic materials for fuel ethanol production, a microorganism capable of high temperature and simultaneous saccharification-fermentation has been required. However, a major drawback is the optimum temperature for the saccharification and fermentation. Most ethanol-fermenting microbes have an optimum temperature for ethanol fermentation ranging between 28 C and 37 C, while the activity of cellulolytic enzymes is highest at around 50 C and significantly decreases with a decrease in temperature. Therefore, in the present study, a thermotolerant yeast, Kluyveromyces marxianus, which has high growth and fermentation at elevated temperatures, was used as a producer of ethanol from cellulose. The strain was genetically engineered to display Trichoderma reesei endoglucanase and Aspergillus aculeatus {beta}-glucosidase on the cell surface, which successfully converts a cellulosic {beta}-glucan to ethanol directly at 48 C with a yield of 4.24 g/l from 10 g/l within 12 h. The yield (in grams of ethanol produced per gram of {beta}-glucan consumed) was 0.47 g/g, which corresponds to 92.2% of the theoretical yield. This indicates that high-temperature cellulose fermentation to ethanol can be efficiently accomplished using a recombinant K. marxianus strain displaying thermostable cellulolytic enzymes on the cell surface. (orig.)

  9. Influence of carbon source, pH, and temperature on the polygalacturonase activity of Kluyveromyces marxianus CCMB 322

    Directory of Open Access Journals (Sweden)

    Rodrigo de Queiroz Oliveira

    2012-09-01

    Full Text Available Microbial pectinolytic enzymes are known to play a commercially important role in a number of industrial processes. Two kinds of yeast can be discerned regarding the production of enzymes. One group includes those which can produce enzymes in the absence of an inducer, and the other group comprises the yeasts that produce enzymes in the presence of an inducer. The objective of this study was to investigate the influence of pectic substances, glucose, pH, and temperature on the polygalacturonase activity by Kluyveromyces marxianus CCMB 322. The yeast was grown in a fermentation broth containing different concentrations of glucose and pectic substances. The polygalacturonase activity was determined by the DNS method, and the pH and temperature were optimized using a central composite experimental design. The polygalacturonase secreted by K. marxianus CCMB 322 was partially constitutive showing optimum pH and temperature of 7.36 and 70 °C, respectively, and maintained approximately 93% of its original activity for 50 minutes at 50 °C. Thermal stability of the polygalacturonase enzyme was studied at different temperatures (50, 60, 70, and 80 °C and different incubation times (0, 10, 20, 30, 40, and 50 minutes. This study showed that glucose can influence the regulation of the synthesis of polygalacturonase.

  10. Consolidated bioprocessing strategy for ethanol production from Jerusalem artichoke tubers by Kluyveromyces marxianus under high gravity conditions.

    Science.gov (United States)

    Yuan, W J; Chang, B L; Ren, J G; Liu, J P; Bai, F W; Li, Y Y

    2012-01-01

    Developing an innovative process for ethanol fermentation from Jerusalem artichoke tubers under very high gravity (VHG) conditions. A consolidated bioprocessing (CBP) strategy that integrated inulinase production, saccharification of inulin contained in Jerusalem artichoke tubers and ethanol production from sugars released from inulin by the enzyme was developed with the inulinase-producing yeast Kluyveromyces marxianus Y179 and fed-batch operation. The impact of inoculum age, aeration, the supplementation of pectinase and nutrients on the ethanol fermentation performance of the CBP system was studied. Although inulinase activities increased with the extension of the seed incubation time, its contribution to ethanol production was negligible because vigorously growing yeast cells harvested earlier carried out ethanol fermentation more efficiently. Thus, the overnight incubation that has been practised in ethanol production from starch-based feedstocks is recommended. Aeration facilitated the fermentation process, but compromised ethanol yield because of the negative Crabtree effect of the species, and increases the risk of contamination under industrial conditions. Therefore, nonaeration conditions are preferred for the CBP system. Pectinase supplementation reduced viscosity of the fermentation broth and improved ethanol production performance, particularly under high gravity conditions, but the enzyme cost should be carefully balanced. Medium optimization was performed, and ethanol concentration as high as 94·2 g l(-1) was achieved when 0·15 g l(-1) K(2) HPO(4) was supplemented, which presents a significant progress in ethanol production from Jerusalem artichoke tubers. A CBP system using K. marxianus is suitable for efficient ethanol production from Jerusalem artichoke tubers under VHG conditions. Jerusalem artichoke tubers are an alternative to grain-based feedstocks for ethanol production. The high ethanol concentration achieved using K. marxianus with the

  11. Kluyveromyces marxianus and Saccharomyces boulardii induce distinct levels of dendritic cell cytokine secretion and significantly different T cell responses In Vitro

    DEFF Research Database (Denmark)

    Smith, Ida Mosbech; Baker, Adam; Christensen, Jeffrey E

    2016-01-01

    induction of a Treg response characterized by robust IL-10 secretion. In addition, we blocked relevant DC surface receptors and investigated the stimulating properties of β-glucan containing yeast cell wall extracts. K. marxianus and S. boulardii induced distinct levels of DC cytokine secretion, primarily...... driven by Dectin-1 recognition of β-glucan components in their cell walls. Upon co-incubation of yeast exposed DCs and naive T cells, S. boulardii induced a potent IFNγ response indicating TH1 mobilization. In contrast, K. marxianus induced a response dominated by Foxp3+ Treg cells, a characteristic...... of the present study was to characterize the immune modulating properties of the food-related yeast Kluyveromyces marxianus in terms of adaptive immune responses indicating inflammation versus tolerance and to explore the mechanisms behind the observed responses. Benchmarking against a Saccharomyces boulardii...

  12. Comparing cell viability and ethanol fermentation of the thermotolerant yeast Kluyveromyces marxianus and Saccharomyces cerevisiae on steam-exploded biomass treated with laccase.

    Science.gov (United States)

    Moreno, Antonio D; Ibarra, David; Ballesteros, Ignacio; González, Alberto; Ballesteros, Mercedes

    2013-05-01

    In this study, the thermotolerant yeast Kluyveromyces marxianus CECT 10875 was compared to the industrial strain Saccharomyces cerevisiae Ethanol Red for lignocellulosic ethanol production. For it, whole slurry from steam-exploded wheat straw was used as raw material, and two process configurations, simultaneous saccharification and fermentation (SSF) and presaccharification and simultaneous saccharification and fermentation (PSSF), were evaluated. Compared to S. cerevisiae, which was able to produce ethanol in both process configurations, K. marxianus was inhibited, and neither growth nor ethanol production occurred during the processes. However, laccase treatment of the whole slurry removed specifically lignin phenols from the overall inhibitory compounds present in the slurry and triggered the fermentation by K. marxianus, attaining final ethanol concentrations and yields comparable to those obtained by S. cerevisiae. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Influence of carbon source, pH, and temperature on the polygalacturonase activity of Kluyveromyces marxianus CCMB 322 Influência da fonte de carbono, pH e temperatura na atividade da enzima poligalacturonase de Kluyveromyces marxianus CCMB 322

    Directory of Open Access Journals (Sweden)

    Rodrigo de Queiroz Oliveira

    2012-09-01

    Full Text Available Microbial pectinolytic enzymes are known to play a commercially important role in a number of industrial processes. Two kinds of yeast can be discerned regarding the production of enzymes. One group includes those which can produce enzymes in the absence of an inducer, and the other group comprises the yeasts that produce enzymes in the presence of an inducer. The objective of this study was to investigate the influence of pectic substances, glucose, pH, and temperature on the polygalacturonase activity by Kluyveromyces marxianus CCMB 322. The yeast was grown in a fermentation broth containing different concentrations of glucose and pectic substances. The polygalacturonase activity was determined by the DNS method, and the pH and temperature were optimized using a central composite experimental design. The polygalacturonase secreted by K. marxianus CCMB 322 was partially constitutive showing optimum pH and temperature of 7.36 and 70 °C, respectively, and maintained approximately 93% of its original activity for 50 minutes at 50 °C. Thermal stability of the polygalacturonase enzyme was studied at different temperatures (50, 60, 70, and 80 °C and different incubation times (0, 10, 20, 30, 40, and 50 minutes. This study showed that glucose can influence the regulation of the synthesis of polygalacturonase.Enzimas pectinolíticas de origem microbiana são conhecidas por desempenhar um papel importante comercialmente em uma série de processos industriais. Dois tipos de levedura podem ser distinguidos para a produção dessas enzimas. Um grupo inclui aqueles que têm capacidade de produzi-las na ausência de um indutor e outro grupo compreende as leveduras que as produzem na presença de um indutor. O objetivo deste estudo foi investigar a influência de substâncias pécticas, de glicose, do pH e da temperatura na atividade da poligalacturonase de Kluyveromyces marxianus CCMB 322. O cultivo foi em caldo de fermentação contendo diferentes

  14. Estudo da produção de beta-galactosidase por fermentação de soro de queijo com Kluyveromyces marxianus Synthesis of beta-galactosidase by fermentation of cheese whey by Kluyveromyces marxianus

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    Patrícia A. Santiago

    2004-12-01

    Full Text Available A hidrólise enzimática da lactose por beta-galactosidase desempenha importante papel no processamento de produtos lácteos, como na obtenção de leite com baixo teor de lactose para consumo por indivíduos intolerantes à mesma e na prevenção da cristalização em produtos de laticínio. Neste trabalho, a enzima beta-galactosidase foi produzida pelo cultivo do microrganismo Kluyveromyces marxianus, em meio de cultura à base de soro de queijo em diferentes concentrações iniciais de lactose e extrato de levedura, de acordo com um planejamento fatorial. As fermentações foram conduzidas em incubador rotativo a 150rpm, a 30°C e pH inicial 5,5. A concentração celular inicial foi de 10(7 células/mL. Para a extração da enzima beta-galactosidase, foi realizada autólise das células utilizando como solvente o clorofórmio em tampão fosfato. No meio de cultura enriquecido com (NH42SO4, KH2PO4 e MgSO4, nas concentrações iniciais de lactose e de extrato de levedura iguais a 50g/L e 12g/L, respectivamente, obteve-se uma atividade de 28,0UGl/mL e uma concentração celular máxima de 5,3g/L.The enzymatic hydrolysis of lactose by beta-galactosidase plays an important role in the processing of milky products such as the production of lactose-hydrolyzed milk for consumption by intolerant person to lactose and the prevention of the crystallization in dairy products. In this work, the influences of nutrient concentrations in the culture medium based on cheese whey were studied with the objective of producing beta-galactosidase from Kluyveromyces marxianus. The fermentations were carried out in a shaker at 30°C and initial pH 5.5 under agitation, starting with an initial cellular concentration of 10(7 cells/mL, varying the initial concentrations of lactose and yeast extract. For extraction of the enzyme of the cells it was used autolysis with chloroform in potassium phosphate buffer. In the medium with a initial lactose concentration of 50g

  15. Identification of auxotrophic mutants of the yeast Kluyveromyces marxianus by non-homologous end joining-mediated integrative transformation with genes from Saccharomyces cerevisiae.

    Science.gov (United States)

    Yarimizu, Tohru; Nonklang, Sanom; Nakamura, Junpei; Tokuda, Shuya; Nakagawa, Takaaki; Lorreungsil, Sasithorn; Sutthikhumpha, Surasit; Pukahuta, Charida; Kitagawa, Takao; Nakamura, Mikiko; Cha-Aim, Kamonchai; Limtong, Savitree; Hoshida, Hisashi; Akada, Rinji

    2013-12-01

    The isolation and application of auxotrophic mutants for gene manipulations, such as genetic transformation, mating selection and tetrad analysis, form the basis of yeast genetics. For the development of these genetic methods in the thermotolerant fermentative yeast Kluyveromyces marxianus, we isolated a series of auxotrophic mutants with defects in amino acid or nucleic acid metabolism. To identify the mutated genes, linear DNA fragments of nutrient biosynthetic pathway genes were amplified from Saccharomyces cerevisiae chromosomal DNA and used to directly transform the K. marxianus auxotrophic mutants by random integration into chromosomes through non-homologous end joining (NHEJ). The appearance of transformant colonies indicated that the specific S. cerevisiae gene complemented the K. marxianus mutant. Using this interspecific complementation approach with linear PCR-amplified DNA, we identified auxotrophic mutations of ADE2, ADE5,7, ADE6, HIS2, HIS3, HIS4, HIS5, HIS6, HIS7, LYS1, LYS2, LYS4, LYS9, LEU1, LEU2, MET2, MET6, MET17, TRP3, TRP4 and TRP5 without the labour-intensive requirement of plasmid construction. Mating, sporulation and tetrad analysis techniques for K. marxianus were also established. With the identified auxotrophic mutant strains and S. cerevisiae genes as selective markers, NHEJ-mediated integrative transformation with PCR-amplified DNA is an attractive system for facilitating genetic analyses in the yeast K. marxianus. Copyright © 2013 John Wiley & Sons, Ltd.

  16. Lignocellulosic sugar management for xylitol and ethanol fermentation with multiple cell recycling by Kluyveromyces marxianus IIPE453.

    Science.gov (United States)

    Dasgupta, Diptarka; Ghosh, Debashish; Bandhu, Sheetal; Adhikari, Dilip K

    2017-07-01

    Optimum utilization of fermentable sugars from lignocellulosic biomass to deliver multiple products under biorefinery concept has been reported in this work. Alcohol fermentation has been carried out with multiple cell recycling of Kluyveromyces marxianus IIPE453. The yeast utilized xylose-rich fraction from acid and steam treated biomass for cell generation and xylitol production with an average yield of 0.315±0.01g/g while the entire glucose rich saccharified fraction had been fermented to ethanol with high productivity of 0.9±0.08g/L/h. A detailed insight into its genome illustrated the strain's complete set of genes associated with sugar transport and metabolism for high-temperature fermentation. A set flocculation proteins were identified that aided in high cell recovery in successive fermentation cycles to achieve alcohols with high productivity. We have brought biomass derived sugars, yeast cell biomass generation, and ethanol and xylitol fermentation in one platform and validated the overall material balance. 2kg sugarcane bagasse yielded 193.4g yeast cell, and with multiple times cell recycling generated 125.56g xylitol and 289.2g ethanol (366mL). Copyright © 2017 Elsevier GmbH. All rights reserved.

  17. Modeling of a simultaneous saccharification and fermentation process for ethanol production from lignocellulosic wastes by kluyveromyces marxianus

    Directory of Open Access Journals (Sweden)

    Juan Esteban Vásquez

    2014-01-01

    Full Text Available En este trabajo se presenta el modelado de las principales dinámicas de un proceso de Sacarificación y Fermentación Simultaneas (SFS utilizando residuos lignocelulósicos como sustrato. Experimentos de SSF llevados a cabo con la levadura Kluyveromyces marxianus como inóculo y desechos de palma de aceite como sustrato se realizaron para obtener datos de concentración de glucosa y etanol que permitieran identificar parámetros y validar el modelo. El modelo resultante predice el comportamiento general de las concentraciones de glucosa y etanol. Gracias a un análisis de sensibilidad, se definen los parámetros que más afectan el modelo, con el fin de flexibilizar el modelo para que pueda ser optimizado en casos particulares con pocos requerimientos computacionales. Esta estrategia de reoptimización muestra mejorar de manera importante la capacidad del modelo para predecir las dinámicas del proceso SSF.

  18. Effects of carbon sources, oxygenation and ethanol on the production of inulinase by Kluyveromyces marxianus YX01

    Directory of Open Access Journals (Sweden)

    JIAOQI GAO

    2012-01-01

    Full Text Available Inulinase is one of the most important factors in consolidated bioprocessing, which combines enzyme production, inulin saccharification, and ethanol fermentation into a single process. In our study, inulinase production and cell growth of Kluyveromyces marxianus YX01 under different conditions were studied. Carbon source was shown to be significant on the production of inulinase, because the activity of inulinase was higher using inulin as a carbon source compared with glucose or fructose. The concentration of the carbon source had a repressive effect on the activity of inulinase. When the concentration was increased to 60 g/L, inulinase activity was only 50% compared with carbon source concentration of 20 g/L. Enzyme activity was also strongly influenced by aeration rate. It has been shown that the activity of inulinase and cell growth under anaerobic conditions were maintained at low levels, but aeration at 1.0 vvm (air volume/broth volume minute led to higher activity. Inulinase activity per unit biomass was not significantly different under different aeration rates. Ethanol had a repressive effect on the cell growth. Cells ceased growing when the level of ethanol was greater than 9% (v/v, but ethanol did not affect the activity of secreted inulinase and the enzyme was stable at ethanol concentration up to 15%.

  19. Kinetics and Regulation Studies of the Production of β-Galactosidase from Kluyveromyces marxianus Grown on Different Substrates

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    Samia Khan

    2003-01-01

    Full Text Available Lactose-intolerance is manifested in 50 % of the world’s population. This can be remediated by removing lactose from the diet or converting it into glucose and galactose with β-galactosidase (EC 3.2.1.23. In this work, batch production of this enzyme in the presence of lactose, galactose, cellobiose, xylose, arabinose, sucrose and glucose was investigated using Kluyveromyces marxianus in shake flask culture studies. Substrate type and temperature were the independent variables that directly regulated the specific growth and β-galactosidase production rates. Lactose (2 % supported the maximum specific product yield (YP/X, followed by galactose, sucrose, cellobiose, xylose, arabinose and glucose. Its synthesis was regulated by an induction and a growth-dependent repression mechanism. The optimum temperature for the production was found to be 35–37 °C. The highest volumetric productivity of enzyme (80.0 IU/L/h occurred on lactose-corn steep liquor medium. This was significantly higher than the calculated values reported in the literature. Thermodynamic studies revealed that the cells provided a defence mechanism against thermal inactivation. The enzyme was stable at 60 °C and pH=5.0–7.0, and it may find application in commercial lactose hydrolysis.

  20. Kinetics of ethanol production by immobilized Kluyveromyces marxianus cells at varying sugar concentrations of Jerusalem artichoke juice

    Energy Technology Data Exchange (ETDEWEB)

    Bajpai, P.; Margaritis, A.

    1987-08-01

    Kinetics of ethanol fermentation at varying sugar concentrations of Jerusalem artichoke tuber extract has been studied using Kluyveromyces marxianus cells immobilized in calcium alginate gel beads. A maximum ethanol concentration of 111 g/l was achieved at an initial sugar concentration of 260 g/l in 20 hours, when the immobilized cell concentration in the calcium alginate beads was 53.3 g dry wt./l bead volume. Ethanol yield remained almost unaffected by initial sugar concentration up to 250 g/l and was found to be about 88% of the theoretical. Maximum rate of ethanol production decreased from 22.5 g ethanol/l/h to 10.5 g ethanol/l/h while the maximum rate of total sugars utilization decreased from 74.9 g sugars/l/h to 28.5 g sugars/l/h as the initial substrate concentration was increased from 100 to 300 g/l. The concentration of free cells in the fermentation broth was low.

  1. Ethanol production from sunflower meal biomass by simultaneous saccharification and fermentation (SSF) with Kluyveromyces marxianus ATCC 36907.

    Science.gov (United States)

    Camargo, Danielle; Gomes, Simone D; Sene, Luciane

    2014-11-01

    The lignocellulosic materials are considered promising renewable resources for ethanol production, but improvements in the processes should be studied to reduce operating costs. Thus, the appropriate enzyme loading for cellulose saccharification is critical for process economics. This study aimed at evaluating the concentration of cellulase and β-glucosidase in the production of bioethanol by simultaneous saccharification and fermentation (SSF) of sunflower meal biomass. The sunflower biomass was pretreated with 6% H2SO4 (w/v), at 121 °C, for 20 min, for hemicellulose removal and delignificated with 1% NaOH. SSF was performed with Kluyveromyces marxianus ATCC 36907, at 38 °C, 150 rpm, for 72 h, with different enzyme concentrations (Cellulase Complex NS22086-10, 15 and 20 FPU/gsubstrate and β-Glucosidase NS22118, with a cellulase to β-glucosidase ratio of 1.5:1; 2:1 and 3:1). The best condition for ethanol production was cellulase 20 FPU/gsubstrate and β-glucosidase 13.3 CBU/gsubstrate, resulting in 27.88 g/L ethanol, yield of 0.47 g/g and productivity of 0.38 g/L h. Under this condition the highest enzymatic conversion of cellulose to glucose was attained (87.06%).

  2. Partial purification and characterization of exoinulinase from Kluyveromyces marxianus YS-1 for preparation of high-fructose syrup.

    Science.gov (United States)

    Singh, Ram Sarup; Dhaliwal, Rajesh; Puri, Munish

    2007-05-01

    An extracellular exoinulinase (2,1-beta-D fructan fructanohydrolase, EC 3.2.1.7), which catalyzes the hydrolysis of inulin into fructose and glucose, was purified 23.5-fold by ethanol precipitation, followed by Sephadex G-100 gel permeation from a cell-free extract of Kluyveromyces marxianus YS-1. The partially purified enzyme exhibited considerable activity between pH 5 to 6, with an optimum pH of 5.5, while it remained stable (100%) for 3 h at the optimum temperature of 50 degrees C. Mn2+ and Ca2+ produced a 2.4-fold and 1.2-fold enhancement in enzyme activity, whereas Hg2+ and Ag2+ completely inhibited the inulinase. A preparation of the partially purified enzyme effectively hydrolyzed inulin, sucrose, and raffinose, yet no activity was found with starch, lactose, and maltose. The enzyme preparation was then successfully used to hydrolyze pure inulin and raw inulin from Asparagus racemosus for the preparation of a high-fructose syrup. In a batch system, the exoinulinase hydrolyzed 84.8% of the pure inulin and 86.7% of the raw Asparagus racemosus inulin, where fructose represented 43.6 mg/ml and 41.3 mg/ml, respectively.

  3. The modeling of ethanol production by Kluyveromyces marxianus using whey as substrate in continuous A-Stat bioreactors.

    Science.gov (United States)

    Gabardo, Sabrina; Pereira, Gabriela Feix; Rech, Rosane; Ayub, Marco Antônio Záchia

    2015-09-01

    We investigated the kinetics of whey bioconversion into ethanol by Kluyveromyces marxianus in continuous bioreactors using the "accelerostat technique" (A-stat). Cultivations using free and Ca-alginate immobilized cells were evaluated using two different acceleration rates (a). The kinetic profiles of these systems were modeled using four different unstructured models, differing in the expressions for the specific growth (μ) and substrate consumption rates (r s), taking into account substrate limitation and product inhibition. Experimental data showed that the dilution rate (D) directly affected cell physiology and metabolism. The specific growth rate followed the dilution rate (μ≈D) for the lowest acceleration rate (a = 0.0015 h(-2)), condition in which the highest ethanol yield (0.52 g g(-1)) was obtained. The highest acceleration rate (a = 0.00667 h(-2)) led to a lower ethanol yield (0.40 g g(-1)) in the system where free cells were used, whereas with immobilized cells ethanol yields increased by 23 % (0.49 g g(-1)). Among the evaluated models, Monod and Levenspiel combined with Ghose and Tyagi models were found to be more appropriate for describing the kinetics of whey bioconversion into ethanol. These results may be useful in scaling up the process for ethanol production from whey.

  4. The effect of gamma irradiation on alcoholic fermentation of cassava by saccharomyces cerevisiae and kluyveromyces marxianus

    International Nuclear Information System (INIS)

    Lina, M.R.; Susiana

    1986-01-01

    A study to examine the influence of gamma irradiation (Co 60 ) on the production of alcohol from cassava by two yeast cultures, S. cerevisiae and a thermotolerant K. marxianus was carried out. Irradiation doses used were 0; 0.1; 0.3; 0.5 and 7 kGy. Two enzymes thermamyl and amyloglucosidase were used for liquifaction and saccharification, respectively. A part of the cassava substrate was enriched with NH 4 H 2 PO 4 as nitrogen source. Irradiated yeast suspension ( + - 10 8 cells/ml) was inoculated to the medium to a final concentration of 5% (v/v). Incubation period was 3 days at a temperature of 30 o C for S. cerevisiae and 37 o C for K. marxianus. Results showed that gamma irradiation had a significant effect on the number of both yeast colonies. It decreased the number of yeast colonies, but not the content of ethanol produced by its fermentation. The yeast still viable after irradiation probably had an increased activity. Adding nitrogen to S. cerevisiae caused a decrease in the content of ethanol, but no significant effect was found on the number of colonies of both yeasts as affected by added nitrogen. (author). 10 refs

  5. Direct fermentation of Jerusalem artichoke tuber powder for production of l-lactic acid and d-lactic acid by metabolically engineered Kluyveromyces marxianus.

    Science.gov (United States)

    Bae, Jung-Hoon; Kim, Hyun-Jin; Kim, Mi-Jin; Sung, Bong Hyun; Jeon, Jae-Heung; Kim, Hyun-Soon; Jin, Yong-Su; Kweon, Dae-Hyuk; Sohn, Jung-Hoon

    2018-01-20

    An efficient production system for optically pure l- and d-lactic acid (LA) from Jerusalem artichoke tuber powder (JAP) was developed by metabolic engineering of Kluyveromyces marxianus. To construct LA-producing strains, the ethanol fermentation pathway of K. marxianus was redirected to LA production by disruption of KmPDC1 and expression of l- and d-lactate dehydrogenase (LDH) genes derived from Lactobacillus plantarum under the control of the K. marxianus translation elongation factor 1α promoter. To further increase the LA titer, the l-LA and d-LA consumption pathway of host strains was blocked by deletion of the oxidative LDH genes KmCYB2 and KmDLD1. The recombinant strains produced 130g/L l-LA and 122g/L d-LA by direct fermentation from 230g/L JAP containing 140g/L inulin, without pretreatment or nutrient supplementation. The conversion efficiency and optical purity were ≫>95% and ≫>99%, respectively. This system using JAP and the inulin-assimilating yeast K. marxianus could lead to a cost-effective process for the production of LA. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Effect of Organic Solvent on the Characteristics of Free and Immobilized Inulinase from Kluyveromyces marxianus ATCC 16045

    Directory of Open Access Journals (Sweden)

    Fernanda V. A. Risso

    2010-01-01

    Full Text Available The aim of this work is to evaluate the effects of the butyl acetate concentration on the characteristics of free and immobilized inulinase from Kluyveromyces marxianus ATCC 16045. The mass fractions of organic solvent (OS in sodium acetate buffer (0.1 M were studied in the range from 25 to 70 %. The characteristics of both free and immobilized enzymes were not significantly affected by the OS mass fraction. The optimal temperature for the free enzyme was 55 °C at all OS mass fractions studied, whereas for the immobilized enzyme the optimum was 55 °C at 70 % of butyl acetate, and in the range from 50 to 60 °C at 25 and 50 % of OS. The optimum pH values, at all OS mass fractions, were 4.8 and 4.4 for the free and immobilized enzymes, respectively. The immobilized enzyme showed more stability at 50 °C and pH=4.8 for the whole range of OS mass fractions, since its stability was improved about 3 times. The kinetics parameters were calculated using Lineweaver-Burk plots. For the free enzyme, the vmax values were 12.5, 58.5 and 37.6 U/mL and the Km values 17.5, 280.7 and 210.4 mM at butyl acetate mass fractions of 25, 50 and 70 %, respectively. Similarly, for the immobilized enzyme, the vmax values were 38.9, 59.5 and 72.5 U/mL and the Km values 3.1, 5.4 and 14.0 mM at the same butyl acetate mass fractions, respectively.

  7. Kluyveromyces marxianus and Saccharomyces boulardii Induce Distinct Levels of Dendritic Cell Cytokine Secretion and Significantly Different T Cell Responses In Vitro.

    Directory of Open Access Journals (Sweden)

    Ida M Smith

    Full Text Available Interactions between members of the intestinal microbiota and the mucosal immune system can significantly impact human health, and in this context, fungi and food-related yeasts are known to influence intestinal inflammation through direct interactions with specialized immune cells in vivo. The aim of the present study was to characterize the immune modulating properties of the food-related yeast Kluyveromyces marxianus in terms of adaptive immune responses indicating inflammation versus tolerance and to explore the mechanisms behind the observed responses. Benchmarking against a Saccharomyces boulardii strain with probiotic effects documented in clinical trials, we evaluated the ability of K. marxianus to modulate human dendritic cell (DC function in vitro. Further, we assessed yeast induced DC modulation of naive T cells toward effector responses dominated by secretion of IFNγ and IL-17 versus induction of a Treg response characterized by robust IL-10 secretion. In addition, we blocked relevant DC surface receptors and investigated the stimulating properties of β-glucan containing yeast cell wall extracts. K. marxianus and S. boulardii induced distinct levels of DC cytokine secretion, primarily driven by Dectin-1 recognition of β-glucan components in their cell walls. Upon co-incubation of yeast exposed DCs and naive T cells, S. boulardii induced a potent IFNγ response indicating TH1 mobilization. In contrast, K. marxianus induced a response dominated by Foxp3+ Treg cells, a characteristic that may benefit human health in conditions characterized by excessive inflammation and positions K. marxianus as a strong candidate for further development as a novel yeast probiotic.

  8. Kluyveromyces marxianus and Saccharomyces boulardii Induce Distinct Levels of Dendritic Cell Cytokine Secretion and Significantly Different T Cell Responses In Vitro.

    Science.gov (United States)

    Smith, Ida M; Baker, Adam; Christensen, Jeffrey E; Boekhout, Teun; Frøkiær, Hanne; Arneborg, Nils; Jespersen, Lene

    2016-01-01

    Interactions between members of the intestinal microbiota and the mucosal immune system can significantly impact human health, and in this context, fungi and food-related yeasts are known to influence intestinal inflammation through direct interactions with specialized immune cells in vivo. The aim of the present study was to characterize the immune modulating properties of the food-related yeast Kluyveromyces marxianus in terms of adaptive immune responses indicating inflammation versus tolerance and to explore the mechanisms behind the observed responses. Benchmarking against a Saccharomyces boulardii strain with probiotic effects documented in clinical trials, we evaluated the ability of K. marxianus to modulate human dendritic cell (DC) function in vitro. Further, we assessed yeast induced DC modulation of naive T cells toward effector responses dominated by secretion of IFNγ and IL-17 versus induction of a Treg response characterized by robust IL-10 secretion. In addition, we blocked relevant DC surface receptors and investigated the stimulating properties of β-glucan containing yeast cell wall extracts. K. marxianus and S. boulardii induced distinct levels of DC cytokine secretion, primarily driven by Dectin-1 recognition of β-glucan components in their cell walls. Upon co-incubation of yeast exposed DCs and naive T cells, S. boulardii induced a potent IFNγ response indicating TH1 mobilization. In contrast, K. marxianus induced a response dominated by Foxp3+ Treg cells, a characteristic that may benefit human health in conditions characterized by excessive inflammation and positions K. marxianus as a strong candidate for further development as a novel yeast probiotic.

  9. Otimização do processo fermentativo e análise do secretoma de Kluyveromyces marxianus UFV-3 em meios contendo lactose em diferentes condições de cultivo

    OpenAIRE

    Diniz, Raphael Hermano Santos

    2013-01-01

    Kluyveromyces marxianus UFV-3 é uma levedura que possui metabolismo respiro-fermentativo, ou seja, a fermentação e respiração coexistem, contudo a via fermentativa ou respiratória pode ser favorecida dependendo da concentração de oxigênio e carboidrato no meio de cultivo. Considerando esta característica das leveduras do gênero Kluyveromyces o objetivo deste trabalho foi otimizar a produção de etanol a partir de permeado de soro de queijo (PSQ) e caracterizar o secretoma de Kluyveromyces marx...

  10. Saccharomyces cerevisiae and Kluyveromyces marxianus Cocultures Allow Reduction of Fermentable Oligo-, Di-, and Monosaccharides and Polyols Levels in Whole Wheat Bread.

    Science.gov (United States)

    Struyf, Nore; Laurent, Jitka; Verspreet, Joran; Verstrepen, Kevin J; Courtin, Christophe M

    2017-10-04

    Fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) are small molecules that are poorly absorbed in the small intestine and rapidly fermented in the large intestine. There is evidence that a diet low in FODMAPs reduces abdominal symptoms in approximately 70% of the patients suffering from irritable bowel syndrome. Wheat contains relatively high fructan levels and is therefore a major source of FODMAPs in our diet. In this study, a yeast-based strategy was developed to reduce FODMAP levels in (whole wheat) bread. Fermentation of dough with an inulinase-secreting Kluyveromyces marxianus strain allowed to reduce fructan levels in the final product by more than 90%, while only 56%  reduction was achieved when a control Saccharomyces cerevisiae strain was used. To ensure sufficient CO 2 production, cocultures of S. cerevisiae and K. marxianus were prepared. Bread prepared with a coculture of K. marxianus and S. cerevisiae had fructan levels ≤0.2% dm, and a loaf volume comparable with that of control bread. Therefore, this approach is suitable to effectively reduce FODMAP levels in bread.

  11. VNTR fingerprinting of Kluyveromyces marxianus strains WT, 7-1, and 8-1 by using different primer types to give best results in PCR and on electrophorese gel in order to find differentiation of the DNA of the yeast strains.

    Science.gov (United States)

    Using mutagenized Kluyveromyces marxianus strains (WT, 7-1, 8-1) we wish to find out the variable numbered tandem repeats (VNTR) of each of the DNA strains from the different mutagenized K. marxianus strains. To do this we used Phusion HF Buffer Pack to try and give a clear picture of the VNTR by u...

  12. Differential RNA-seq, Multi-Network Analysis and Metabolic Regulation Analysis of Kluyveromyces marxianus Reveals a Compartmentalised Response to Xylose.

    Directory of Open Access Journals (Sweden)

    Du Toit W P Schabort

    Full Text Available We investigated the transcriptomic response of a new strain of the yeast Kluyveromyces marxianus, in glucose and xylose media using RNA-seq. The data were explored in a number of innovative ways using a variety of networks types, pathway maps, enrichment statistics, reporter metabolites and a flux simulation model, revealing different aspects of the genome-scale response in an integrative systems biology manner. The importance of the subcellular localisation in the transcriptomic response is emphasised here, revealing new insights. As was previously reported by others using a rich medium, we show that peroxisomal fatty acid catabolism was dramatically up-regulated in a defined xylose mineral medium without fatty acids, along with mechanisms to activate fatty acids and transfer products of β-oxidation to the mitochondria. Notably, we observed a strong up-regulation of the 2-methylcitrate pathway, supporting capacity for odd-chain fatty acid catabolism. Next we asked which pathways would respond to the additional requirement for NADPH for xylose utilisation, and rationalised the unexpected results using simulations with Flux Balance Analysis. On a fundamental level, we investigated the contribution of the hierarchical and metabolic regulation levels to the regulation of metabolic fluxes. Metabolic regulation analysis suggested that genetic level regulation plays a major role in regulating metabolic fluxes in adaptation to xylose, even for the high capacity reactions, which is unexpected. In addition, isozyme switching may play an important role in re-routing of metabolic fluxes in subcellular compartments in K. marxianus.

  13. Growth and ethanol fermentation ability on hexose and pentose sugars and glucose effect under various conditions in thermotolerant yeast Kluyveromyces marxianus.

    Science.gov (United States)

    Rodrussamee, Nadchanok; Lertwattanasakul, Noppon; Hirata, Katsushi; Suprayogi; Limtong, Savitree; Kosaka, Tomoyuki; Yamada, Mamoru

    2011-05-01

    Ethanol fermentation ability of the thermotolerant yeast Kluyveromyces marxianus, which is able to utilize various sugars including glucose, mannose, galactose, xylose, and arabinose, was examined under shaking and static conditions at high temperatures. The yeast was found to produce ethanol from all of these sugars except for arabinose under a shaking condition but only from hexose sugars under a static condition. Growth and sugar utilization rate under a static condition were slower than those under a shaking condition, but maximum ethanol yield was slightly higher. Even at 40°C, a level of ethanol production similar to that at 30°C was observed except for galactose under a static condition. Glucose repression on utilization of other sugars was observed, and it was more evident at elevated temperatures. Consistent results were obtained by the addition of 2-deoxyglucose. The glucose effect was further examined at a transcription level, and it was found that KmGAL1 for galactokinase and KmXYL1 for xylose reductase for galactose and xylose/arabinose utilization, respectively, were repressed by glucose at low and high temperatures, but KmHXK2 for hexokinase was not repressed. We discuss the possible mechanism of glucose repression and the potential for utilization of K. marxianus in high-temperature fermentation with mixed sugars containing glucose.

  14. Improving the Organoleptic Properties of a Craft Mezcal Beverage by Increasing Fatty Acid Ethyl Ester Contents through ATF1 Expression in an Engineered Kluyveromyces marxianus UMPe-1 Yeast.

    Science.gov (United States)

    Campos-García, Jesús; Vargas, Alejandra; Farías-Rosales, Lorena; Miranda, Ana L; Meza-Carmen, Víctor; Díaz-Pérez, Alma L

    2018-05-02

    Mezcal, a traditional beverage that originated in Mexico, is produced from species of the Agavaceae family. The esters associated with the yeasts utilized during fermentation are important for improving the organoleptic properties of the beverage. We improved the ester contents in a mezcal beverage by using the yeast Kluyveromyces marxianus, which was engineered with the ATF1 gene. ATF1 expression in the recombinant yeast significantly increased compared with that in the parental yeast, but its fermentative parameters were unchanged. Volatile-organic-compound-content analysis showed that esters had significantly increased in the mezcal produced with the engineered yeast. In a sensory-panel test, 48% of the panelists preferred the mezcal produced from the engineered yeast, 30% preferred the mezcal produced from the wild type, and 15 and 7% preferred the two mezcal types produced following the routine procedure. Correlation analysis showed that the fruitiness/sweetness description of the mezcal produced using the ATF1-engineered K. marxianus yeast correlated with the content of the esters, whose presence improved the organoleptic properties of the craft mezcal beverage.

  15. Growth and ethanol fermentation ability on hexose and pentose sugars and glucose effect under various conditions in thermotolerant yeast Kluyveromyces marxianus

    Energy Technology Data Exchange (ETDEWEB)

    Rodrussamee, Nadchanok; Hirata, Katsushi; Suprayogi [Yamaguchi Univ., Ube (Japan). Graduate School of Medicine; Lertwattanasakul, Noppon; Kosaka, Tomoyuki [Yamaguchi Univ. (Japan). Faculty of Agriculture; Limtong, Savitree [Kasetsart Univ., Bangkok (Thailand). Faculty of Science; Yamada, Mamoru [Yamaguchi Univ., Ube (Japan). Graduate School of Medicine; Yamaguchi Univ. (Japan). Faculty of Agriculture

    2011-05-15

    Ethanol fermentation ability of the thermotolerant yeast Kluyveromyces marxianus, which is able to utilize various sugars including glucose, mannose, galactose, xylose, and arabinose, was examined under shaking and static conditions at high temperatures. The yeast was found to produce ethanol from all of these sugars except for arabinose under a shaking condition but only from hexose sugars under a static condition. Growth and sugar utilization rate under a static condition were slower than those under a shaking condition, but maximum ethanol yield was slightly higher. Even at 40 C, a level of ethanol production similar to that at 30 C was observed except for galactose under a static condition. Glucose repression on utilization of other sugars was observed, and it was more evident at elevated temperatures. Consistent results were obtained by the addition of 2-deoxyglucose. The glucose effect was further examined at a transcription level, and it was found that KmGAL1 for galactokinase and KmXYL1 for xylose reductase for galactose and xylose/arabinose utilization, respectively, were repressed by glucose at low and high temperatures, but KmHXK2 for hexokinase was not repressed. We discuss the possible mechanism of glucose repression and the potential for utilization of K. marxianus in high-temperature fermentation with mixed sugars containing glucose. (orig.)

  16. Automated UV-C mutagenesis of Kluyveromyces marxianus NRRL Y-1109 and selection for microaerophilic growth and ethanol production at elevated temperature on biomass sugars.

    Science.gov (United States)

    Hughes, Stephen R; Bang, Sookie S; Cox, Elby J; Schoepke, Andrew; Ochwat, Kate; Pinkelman, Rebecca; Nelson, Danielle; Qureshi, Nasib; Gibbons, William R; Kurtzman, Cletus P; Bischoff, Kenneth M; Liu, Siqing; Cote, Gregory L; Rich, Joseph O; Jones, Marjorie A; Cedeño, David; Doran-Peterson, Joy; Riaño-Herrera, Nestor M; Rodríguez-Valencia, Nelson; López-Núñez, Juan C

    2013-08-01

    The yeast Kluyveromyces marxianus is a potential microbial catalyst for fuel ethanol production from a wide range of biomass substrates. To improve its growth and ethanol yield at elevated temperature under microaerophilic conditions, K. marxianus NRRL Y-1109 was irradiated with UV-C using automated protocols on a robotic platform for picking and spreading irradiated cultures and for processing the resulting plates. The plates were incubated under anaerobic conditions on xylose or glucose for 5 mo at 46 °C. Two K. marxianus mutant strains (designated 7-1 and 8-1) survived and were isolated from the glucose plates. Both mutant strains, but not wild type, grew aerobically on glucose at 47 °C. All strains grew anaerobically at 46 °C on glucose, galactose, galacturonic acid, and pectin; however, only 7-1 grew anaerobically on xylose at 46 °C. Saccharomyces cerevisiae NRRL Y-2403 did not grow at 46 °C on any of these substrates. With glucose as a carbon source, ethanol yield after 3 d at 46 °C was higher for 8-1 than for wild type (0.51 and 0.43 g ethanol/g glucose, respectively). With galacturonic acid as a carbon source, the ethanol yield after 7 d at 46 °C was higher for 7-1 than for wild type (0.48 and 0.34 g ethanol/g galacturonic acid, respectively). These mutant strains have potential application in fuel ethanol production at elevated temperature from sugar constituents of starch, sucrose, pectin, and cellulosic biomass.

  17. Ethanol yield and volatile compound content in fermentation of agave must by Kluyveromyces marxianus UMPe-1 comparing with Saccharomyces cerevisiae baker's yeast used in tequila production.

    Science.gov (United States)

    López-Alvarez, Arnoldo; Díaz-Pérez, Alma Laura; Sosa-Aguirre, Carlos; Macías-Rodríguez, Lourdes; Campos-García, Jesús

    2012-05-01

    In tequila production, fermentation is an important step. Fermentation determines the ethanol productivity and organoleptic properties of the beverage. In this study, a yeast isolated from native residual agave must was identified as Kluyveromyces marxianus UMPe-1 by 26S rRNA sequencing. This yeast was compared with the baker's yeast Saccharomyces cerevisiae Pan1. Our findings demonstrate that the UMPe-1 yeast was able to support the sugar content of agave must and glucose up to 22% (w/v) and tolerated 10% (v/v) ethanol concentration in the medium with 50% cells survival. Pilot and industrial fermentation of agave must tests showed that the K. marxianus UMPe-1 yeast produced ethanol with yields of 94% and 96% with respect to fermentable sugar content (glucose and fructose, constituting 98%). The S. cerevisiae Pan1 baker's yeast, however, which is commonly used in some tequila factories, showed 76% and 70% yield. At the industrial level, UMPe-1 yeast shows a maximum velocity of fermentable sugar consumption of 2.27g·L(-1)·h(-1) and ethanol production of 1.38g·L(-1)·h(-1), providing 58.78g ethanol·L(-1) at 72h fermentation, which corresponds to 96% yield. In addition, the major and minor volatile compounds in the tequila beverage obtained from UMPe-1 yeast were increased. Importantly, 29 volatile compounds were identified, while the beverage obtained from Pan1-yeast contained fewer compounds and in lower concentrations. The results suggest that the K. marxianus UMPe-1 is a suitable yeast for agave must fermentation, showing high ethanol productivity and increased volatile compound content comparing with a S. cerevisiae baker's yeast used in tequila production. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  18. Novel technology development through thermal drying of encapsulated Kluyveromyces marxianus in micro- and nano-tubular cellulose in lactose fermentation and its evaluation for food production.

    Science.gov (United States)

    Papapostolou, Harris; Servetas, Yiannis; Bosnea, Loulouda A; Kanellaki, Maria; Koutinas, Athanasios A

    2012-12-01

    A novel technology development based on the production of a low-cost starter culture for ripening of cheeses and baking is reported in the present study. The starter culture comprises thermally dried cells of Kluyveromyces marxianus encapsulated in micro- and nano-tubular cellulose. For production of a low-cost and effective biocatalyst, whey was used as raw material for biomass production and thermal drying methods (convective, conventional, and vacuum) were applied and evaluated at drying temperatures ranging from 35 to 60 °C. The effect of drying temperature of biocatalysts on fermentability of lactose and whey was evaluated. Storage stability and suitability of biocatalysts as a commercial starter cultures was also assessed and evaluated. All thermally dried biocatalysts were found to be active in lactose and whey fermentation. In all cases, there was sugar conversion ranging from 92 to 100 %, ethanol concentration of up to 1.47 % (v/v), and lactic acid concentrations ranged from 4.1 to 5.5 g/l. However, convective drying of the encapsulated cells of K. marxianus in micro- and nano-tubular cellulose was faster and a more effective drying method while drying at 42 °C appear to be the best drying temperature in terms of cell activity, ethanol, and lactic acid formation. Storage of the biocatalysts for 3 months at 4 °C proved maintenance of its activity even though fermentation times increased by 50-100 % compared with the fresh dried ones.

  19. OBTENCIÓN DE UNA BEBIDA FERMENTADA A PARTIR DE SUERO DE QUESO UTILIZANDO CÉLULAS INMOVILIZADAS DE KLUYVEROMYCES MARXIANUS

    Directory of Open Access Journals (Sweden)

    Rocío Cóndor G.

    2014-06-01

    Full Text Available El presente estudio tuvo como objetivo principal optimizar la tecnología de producción de una bebida fermentada de suero de queso, utilizando Kluyveromyces marxianus e inmovilización de células. En el biorreactor de lecho empacado, se obtuvo el mayor rendimiento (11,46±0,81 oGL con un flujo de 140-150 mL. h-1, una biomasa inmovilizada de 10% (v/v, una relación de columna de 1:12 (diámetro: longitud, tamaño de perlas de 3 mm de diámetro, adición de metabisulfito de sodio (100 pg. mL-1 y células inmovilizadas con 2% (p/v de alginato. Luego de optimizado todos los parámetros de fermentación en el biorreactor, la bebida alcohólica fue sometida a inactivación a 70 oC por 5 minutos (tratamiento térmico y clarificación con tierra de diatomeas (11 kg. M-2. Finalmente, la bebida alcohólica fue evaluada en almacenamiento por 6 meses, durante este período se le hicieron evaluaciones fisicoquímicas, microbiológicas y sensoriales. Se determinó por Escala Hedónica y Ranking que la bebida alcohólica de suero tiene aceptabilidad.

  20. Growth, ethanol production, and inulinase activity on various inulin substrates by mutant Kluyveromyces marxianus strains NRRL Y-50798 and NRRL Y-50799.

    Science.gov (United States)

    Galindo-Leva, Luz Ángela; Hughes, Stephen R; López-Núñez, Juan Carlos; Jarodsky, Joshua M; Erickson, Adam; Lindquist, Mitchell R; Cox, Elby J; Bischoff, Kenneth M; Hoecker, Eric C; Liu, Siqing; Qureshi, Nasib; Jones, Marjorie A

    2016-07-01

    Economically important plants contain large amounts of inulin. Disposal of waste resulting from their processing presents environmental issues. Finding microorganisms capable of converting inulin waste to biofuel and valuable co-products at the processing site would have significant economic and environmental impact. We evaluated the ability of two mutant strains of Kluyveromyces marxianus (Km7 and Km8) to utilize inulin for ethanol production. In glucose medium, both strains consumed all glucose and produced 0.40 g ethanol/g glucose at 24 h. In inulin medium, Km7 exhibited maximum colony forming units (CFU)/mL and produced 0.35 g ethanol/g inulin at 24 h, while Km8 showed maximum CFU/mL and produced 0.02 g ethanol/g inulin at 96 h. At 24 h in inulin + glucose medium, Km7 produced 0.40 g ethanol/g (inulin + glucose) and Km8 produced 0.20 g ethanol/g (inulin + glucose) with maximum CFU/mL for Km8 at 72 h, 40 % of that for Km7 at 36 h. Extracellular inulinase activity at 6 h for both Km7 and Km8 was 3.7 International Units (IU)/mL.

  1. 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.

  2. Purification and characterization of a novel tannase produced by Kluyveromyces marxianus using olive pomace as solid support, and its promising role in gallic acid production.

    Science.gov (United States)

    Mahmoud, Abeer E; Fathy, Shadia A; Rashad, Mona M; Ezz, Magda K; Mohammed, Amira T

    2018-02-01

    Tannase is considered one of the most important industrial enzymes that find great applications in various sectors. Production of tannases through solid state fermentation (SSF) using agro-industrial wastes is an eco-friendly and cheap technology. Tannase was produced by the yeast Kluyveromyces marxianus using olive pomace as a solid support under SSF. It was purified using ammonium sulfate fractional precipitation followed by Sephadex G-200 gel filtration resulting in 64.6% enzyme yield with 1026.12U/mg specific activity and 24.21 purification fold. Pure tannase had molecular weight of 65 KDa and 66.62 KDa by SDS-PAGE and gel filtration, respectively. It showed a maximal activity at 35°C having two different pH optima, one of which is acidic (4.5) and the other one is alkaline (8.5). The enzyme was stable in the acidic range of pH (4.0-5.5) for 30min, and thermostable within the temperature range 30-70°C. Using tannic acid, the enzyme had a Km value of 0.77mM and Vmax of 263.20μmolemin -1 ml -1 . The effect of different metal ions on enzymatic activity was evaluated. HPLC analysis data indicated that the purified enzyme could carry out 24.65% tannic acid conversion with 5.25 folds increase in gallic acid concentration within 30min only. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Novel transporters from Kluyveromyces marxianus and Pichia guilliermondii expressed in Saccharomyces cerevisiae enable growth on L-arabinose and D-xylose.

    Science.gov (United States)

    Knoshaug, Eric P; Vidgren, Virve; Magalhães, Frederico; Jarvis, Eric E; Franden, Mary Ann; Zhang, Min; Singh, Arjun

    2015-10-01

    Genes encoding L-arabinose transporters in Kluyveromyces marxianus and Pichia guilliermondii were identified by functional complementation of Saccharomyces cerevisiae whose growth on L-arabinose was dependent on a functioning L-arabinose transporter, or by screening a differential display library, respectively. These transporters also transport D-xylose and were designated KmAXT1 (arabinose-xylose transporter) and PgAXT1, respectively. Transport assays using L-arabinose showed that KmAxt1p has K(m) 263 mM and V(max) 57 nM/mg/min, and PgAxt1p has K(m) 0.13 mM and V(max) 18 nM/mg/min. Glucose, galactose and xylose significantly inhibit L-arabinose transport by both transporters. Transport assays using D-xylose showed that KmAxt1p has K(m) 27 mM and V(max) 3.8 nM/mg/min, and PgAxt1p has K(m) 65 mM and V(max) 8.7 nM/mg/min. Neither transporter is capable of recovering growth on glucose or galactose in a S. cerevisiae strain deleted for hexose and galactose transporters. Transport kinetics of S. cerevisiae Gal2p showed K(m) 371 mM and V(max) 341 nM/mg/min for L-arabinose, and K(m) 25 mM and V(max) 76 nM/mg/min for galactose. Due to the ability of Gal2p and these two newly characterized transporters to transport both L-arabinose and D-xylose, one scenario for the complete usage of biomass-derived pentose sugars would require only the low-affinity, high-throughput transporter Gal2p and one additional high-affinity general pentose transporter, rather than dedicated D-xylose or L-arabinose transporters. Additionally, alignment of these transporters with other characterized pentose transporters provides potential targets for substrate recognition engineering. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Caracterização cinética e termodinâmica de β-galactosidase de Kluyveromyces marxianus CCT 7082 fracionada com sulfato de amônio Kinetics and thermodynamic characterization of β-galactosidase from Kluyveromyces marxianus CCT 7082 fractionated with ammonium sulphate

    Directory of Open Access Journals (Sweden)

    Renata Bemvenuti Heidtmann

    2012-03-01

    Full Text Available A β-galactosidase é uma enzima importante que atua na hidrólise da lactose, podendo ser empregada na obtenção de alimentos destinados a consumidores intolerantes a esse dissacarídeo. A levedura Kluyveromyces marxianus apresenta bom rendimento de crescimento, além de ser um micro-organismo seguro em aplicações industriais, e tem sido utilizada para produção da enzima por cultivo submerso. A β-galactosidase obtida foi fracionada com sulfato de amônio e caracterizada quanto a temperatura e pH ótimos, estabilidade térmica, valores D e z, e parâmetros cinéticos e termodinâmicos. A temperatura e pH ótimos foram de 45-50 °C e 7,0, respectivamente. A energia de ativação da reação enzimática foi de 9,8 kcal.mol-1 e da reação de desativação, 64,2 kcal.mol-1. Os valores de Km e Vmax obtidos foram de 3,7 mM e 99,0 U.mL-1, respectivamente. A energia livre de Gibbs reduziu com o aumento de temperatura, sendo a enzima mais estável a 30 °C (∆G* = 106,8 kJ.mol-1. A entalpia foi de 313,04 kJ.mol-1 e a entropia 0,68 kJ.mol-1.k-1. O valor D confirmou que a enzima foi mais estável em temperaturas próximas de 30 °C (D = 11.513,0 min e o valor z foi de 5,8 °C.β-galactosidase is an important enzyme that acts on lactose hydrolysis and can be used to obtain food for consumers intolerant to this disaccharide. The yeast Kluyveromyces marxianus presents a good growth yield, is a safe microorganism for industrial applications and has been used for enzyme production using the submerged process. The β-galactosidase obtained was fractionated with ammonium sulphate and characterized with respect to its optimum temperature and pH, thermal stability and its D and z values, as well as its kinetic and thermodynamic parameters. The optimum temperature and pH were 45-50 °C and 7.0, respectively. The activation energy and the deactivation reaction of the enzymatic reaction were, respectively, 9.8 kcal.mol-1 and 64.2 kcal.mol-1. The Km and Vmax

  5. Measurement of atmospheric neutrino composition with the IMB-3 detector

    International Nuclear Information System (INIS)

    Casper, D.; Becker-Szendy, R.; Bratton, C.B.; Cady, D.R.; Claus, R.; Dye, S.T.; Gajewski, W.; Goldhaber, M.; Haines, T.J.; Halverson, P.G.; Jones, T.W.; Kielczewska, D.; Kropp, W.R.; Learned, J.G.; LoSecco, J.M.; McGrew, C.; Matsuno, S.; Matthews, J.; Mudan, M.S.; Price, L.; Reines, F.; Schultz, J.; Sinclair, D.; Sobel, H.W.; Stone, J.L.; Sulak, L.R.; Svoboda, R.; Thornton, G.; van der Velde, J.C.; The University of Michigan, Ann Arbor, Michigan 48109 Brookhaven National; Laboratory, Upton, New York 11973; Boston University, Boston, Massachusetts 02215; The University of Hawaii, Honolulu, Hawaii 96822 University College, London, WC1E F6BT, United Kingdom; Warsaw University, Warsaw, Poland; Cleveland State University, Cleveland, Ohio 44115; The University of Notre Dame, Notre Dame, Indiana 46556; Lousiana State University, Baton Rouge, Lousisiana 70803; The University of Maryland, College Park, Maryland 20742)

    1991-01-01

    The atmospheric neutrino flux is measured using a 3.4-kt yr exposure of the IMB-3 detector. Single-ring events are classified as showering or nonshowering using the geometry of the Cerenkov pattern. A simulation of neutrino interactions and three models of atmospheric neutrino production are used to predict the composition of the sample. Showering-nonshowering character is strongly correlated with the flavor of the neutrino parent. In the lepton momentum range p<1500 MeV/c, we find that nonshowering events comprise [41±3±2syst]% of the total. The fraction expected is [51±5(syst)]%

  6. Lactose hydrolysis in aqueous two-phase system by whole-cell {beta}-galactosidase of Kluyveromyces marxianus. Semicontinuous and continuous processes

    Energy Technology Data Exchange (ETDEWEB)

    Tomaska, M [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology; Stredansky, M [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology; Tomaskova, A [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology; Sturdik, E [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology

    1995-01-01

    Semicontinuous and continuous hydrolysis of lactose in aqueous two-phase systems (polyethylene glycol 20000/ dextran 40) with whole-cell {beta}-galactosidase of K. marxianus were studied. Both phase polymers had no effect on {beta}-galactosidase activity confined in cells. Good operational stability of the biocatalyst during 55 cycles of semicontinuous process was observed without appreciable decrease in product concentration. Continuous hydrolysis of lactose was performed in the stirred bioreactor, connected with the phase separator. The satisfactory degree of hydrolysis (between 82-88%) and volumetric productivity (21.6 g/l/h) were reached during 72 hours of continuous hydrolysis of 5% (w/w) lactose. (orig.)

  7. Modelación matemática del efecto de la temperatura en la actividad y la estabilidad térmica de la inulinasa de Kluyveromyces marxianus NRRL Y-7571

    Directory of Open Access Journals (Sweden)

    Jesús Diestra Balta

    2015-01-01

    Full Text Available Un modelo matemático se utilizó en este estudio para describir el efecto de la temperatura en la actividad y la estabilidad térmica (condiciones no reactivas de la inulinasa de Kluyveromyces marxianus NRRL Y-7571. El modelo se tomó de la literatura, el cual se desarrolló utilizando la ecuación de Arrhenius y los datos experimentales. Una ecuación cinética de primer orden se asumió para la inactivación enzimática. Los parámetros del modelo se determinaron por regresión lineal y no lineal, reportando los intervalos de confianza. Los datos experimentales demostraron que la actividad máxima actuando en sacarosa e inulina se alcanzó a 55 °C y que estas actividades fueron altamente sensibles a temperaturas más altas. Además, la actividad inulolítica fue más estable térmicamente que la de invertasa en el rango de 48 a 60 °C.Utilizando el modelo, la temperatura del proceso para la hidrólisis de sacarosa e inulina se determinó en la intersección de las curvas de la actividad relativa y el tiempo de vida media relativo, resultando 49 °C para ambos procesos. Aunque este modelo se utilizó con referencia a la hidrólisis de la sacarosa e inulina, el enfoque es una herramienta útil que se puede aplicar a otros procesos enzimáticos para la determinación de la temperatura de operación, la que es últimamente determinada por una evaluación económica.

  8. Modelling of a Batch Whey Cultivation of Kluyveromyces marxianus var. lactis MC 5 with Investigation of Mass Transfer Processes in the Bioreactor

    Directory of Open Access Journals (Sweden)

    Mitko Petrov

    2015-04-01

    Full Text Available This study presents a mathematical model of a batch fermentation of lactose oxidation from a natural substratum in a cultivation by the strain Kluyweromyces marxianus var. lactis MC 5. In the model of the process, the mass transfer in the bioreactor for oxygen concentration in the gas phase (GP and in the liquid phase (LP is based on the dispersion model of the GP. In addition, perfect mixing in LP is included. Nine models were investigated for specific growth rate and specific oxygen consumptions rate: Monod, Mink, Tessier, Aiba, Andrews, Haldane, Luong, Edward and Han-Levenspiel. In regard to the parameter estimation, the worst observed error was used for all experiments as an objective function. This approach is a special case of multi objective parameter estimation problems allowing the parameter estimation problem to become a min-max problem. The results obtained (values of criteria, relative error and statistics λ for the specific growth rate showed that the best fit to experimental data is achieved when applying the Mink model. In a combination a Mink, and Monod, Mink, Luong, Haldane, and Han-Levenspiel are used for specific oxygen consumptions rate. Based on the investigation, it was discovered that the best fit belonged to the models of Mink and Haldane, Mink and Luong and Mink and Han-Levenspiel. Therefore, these particular models are used for modeling the batch processes.

  9. Experimental Neutrino Physics and Astrophysics with the IMB-3 Detector

    Science.gov (United States)

    Casper, David William

    1990-01-01

    Description of the universe on the smallest (elementary particle physics) and largest (cosmology) scales has become dependent on the properties of the most weakly interacting fundamental particle known, the neutrino. The IMB experiment, designed to study nucleon decay, is also the world's largest detector of neutrinos. The experiment uses 6800 tons (3300 tons fiducial) of water as both target and detecting medium. Relativistic charges particles traversing the water radiate Cerenkov light. The distinctive ring patterns are imaged by 2048 light collectors (each a photo-multiplier tube coupled with a wavelength-shifting plate) distributed over the surfaces of the tank. This dissertation describes the IMB-3 detector, a four-fold increase in sensitivity over the original apparatus. Neutrino interactions of both atmospheric and extragalactic origin were collected during a 3.4 kiloton-year exposure. A consequence of non-zero neutrino mass could be oscillation of neutrino flavor. The energies and long flight distances of atmospheric neutrinos offer a unique opportunity to explore this possibility. To study the composition of the atmospheric neutrinos, single-ring events are classified as showering or non-showering using the geometry of the Cerenkov pattern. A simulation of neutrino interactions and a model of atmospheric neutrino production are used to predict the composition of the sample. The showering/non-showering character of an event is strongly correlated with the flavor of its neutrino parent. In the lepton momentum range p mass or "dark matter" problem result in high-energy neutrino production within the Sun. A model of dark matter capture and annihilation in the Sun predicts the resulting neutrino fluxes at Earth. No evidence of the phenomenon is observed, but for canonical values of dark matter density and velocity in the solar system, greater exposure will be required to verify or exclude the expected signal.

  10. Yeast Kluyveromyces lactis as host for expression of the bacterial lipase: cloning and adaptation of the new lipase gene from Serratia sp.

    Science.gov (United States)

    Šiekštelė, Rimantas; Veteikytė, Aušra; Tvaska, Bronius; Matijošytė, Inga

    2015-10-01

    Many microbial lipases have been successfully expressed in yeasts, but not in industrially attractive Kluyveromyces lactis, which among other benefits can be cultivated on a medium supplemented with whey--cheap and easily available industrial waste. A new bacterial lipase from Serratia sp. was isolated and for the first time expressed into the yeast Kluyveromyces lactis by heterologous protein expression system based on a strong promoter of Kluyveromyces marxianus triosephosphate isomerase gene and signal peptide of Kluyveromyces marxianus endopolygalacturonase gene. In addition, the bacterial lipase gene was synthesized de novo by taking into account a codon usage bias optimal for K. lactis and was expressed into the yeast K. lactis also. Both resulting strains were characterized by high output level of the target protein secreted extracellularly. Secreted lipases were characterized for activity and stability.

  11. Kinetics of ethanol production from Jerusalem artichoke juice with some Kluyveromyces species

    Energy Technology Data Exchange (ETDEWEB)

    Kuvnjak, Z.; Kosaric, N.; Hayes, R.D.

    1981-01-01

    The kinetics of ethanol production by Kluyveromyces marxianus ATCC 12708 and ATCC 10606, K. cicerisporus ATCC 22295 and K. fragilis 105 were studied using raw juice of the Jerusalem artichoke in which the carbohydrates were not hydrolyzed prior to fermentation. This juice contains enough nutrients and can serve as a complete medium without additional nutrients both for growth of the yeasts and for ethanol production. Both specific ethanol productivity and specific glucose uptake rates were the highest with K. marxianus ATCC 12708 (1.68 gg-1 h-1 and 3.78 gg-1h-1, respectively). This microorganism produced an ethanol yield of 87.5% of the theoretical value in 25 hours.

  12. Optimisation of Inulinase Production by Kluyveromyces bulgaricus

    Directory of Open Access Journals (Sweden)

    Darija Vranešić

    2002-01-01

    Full Text Available The present work is based on observation of the effects of pH and temperature of fermentation on the production of microbial enzyme inulinase by Kluyveromyces marxianus var. bulgaricus. Inulinase hydrolyzes inulin, a polysaccharide which can be isolated from plants such as Jerusalem artichoke, chicory or dahlia, and transformed into pure fructose or fructooligosaccharides. Fructooligosaccharides have great potential in food industry because they can be used as calorie-reduced compounds and noncariogenic sweeteners as well as soluble fibre and prebiotic compounds. Fructose formation from inulin is a single step enzymatic reaction and yields are up to 95 % the fructose. On the contrary, conventional fructose production from starch needs at least three enzymatic steps, yielding only 45 % of fructose. The process of inulinase production was optimised by using experimental design method. pH value of the cultivation medium showed to be the most significant variable and it should be maintained at optimum value of 3.6. The effect of temperature was slightly lower and optimal values were between 30 and 33 °C. At a low pH value of the cultivation medium, the microorganism was not able to producem enough enzyme and enzyme activities were low. Similar effect was caused by high temperature. The highest values of enzyme activities were achieved at optimal fermentation conditions and the values were: 100.16–124.36 IU/mL (with sucrose as substrate for determination of enzyme activity or 8.6–11.6 IU/mL (with inulin as substrate, respectively. The method of factorial design and response surface analysis makes it possible to study several factors simultaneously, to quantify the individual effect of each factor and to investigate their possible interactions. As a comparison to this method, optimisation of a physiological enzyme activity model depending on pH and temperature was also studied.

  13. A biochemically structured model for ethanol fermentation by Kluyveromyces marxianus: A batch fermentation and kinetic study

    DEFF Research Database (Denmark)

    Sansonetti, Sascha; Hobley, Timothy John; Calabrò, V.

    2011-01-01

    Anaerobic batch fermentations of ricotta cheese whey (i.e. containing lactose) were performed under different operating conditions. Ethanol concentrations of ca. 22gL−1 were found from whey containing ca. 44gL−1 lactose, which corresponded to up to 95% of the theoretical ethanol yield within 15h......, lactose, biomass and glycerol during batch fermentation could be described within a ca. 6% deviation, as could the yield coefficients for biomass and ethanol produced on lactose. The model structure confirmed that the thermodynamics considerations on the stoichiometry of the system constrain the metabolic...... coefficients within a physically meaningful range thereby providing valuable and reliable insight into fermentation processes....

  14. Efecto de Sacharomyces cerevisiae y Kluyveromices marxianus durante el tiempo de fermentación en la calidad nutritiva del nopal forrajero / Effect of Sacharomyces cerevisiae and Kluyveromices marxianus on the nutritional quality of the forage prickly pear during the time of fermentation

    Directory of Open Access Journals (Sweden)

    Esperanza Herrera-Torres

    2014-01-01

    Full Text Available Recientemente, el nopal forrajero se ha introducido en la alimentación animal. Sin embargo, una limitante del nopal es su bajo contenido de proteína cruda. Una tecnología que se puede utilizar para incrementar la calidad nutritiva del nopal es la fermentación en estado sólido (FES. Por lo tanto, el objetivo de este trabajo fue evaluar el efecto de Kluyveromyces marxianus y Saccharomyces cerevisiae en la dinámica de fermentación del nopal forrajero. Se colocaron 250 g de nopal picado con el 1 % de levadura en matraces de 500 ml, los cuales se incubaron por 24, 48, 72 y 96 h a 32 °C y 28 °C para K. marxianus y S. cerevisiae, respectivamente. A las muestras secas del nopal fermentado se les determinaron los contenidos de materia seca (MS, proteína cruda (PC, fibra detergente neutro (FDN, fibra detergente ácido (FDA, lignina (L y digestibilidad verdadera in vitro de la MS (DVIVMS. Los datos obtenidos fueron analizados con un diseño completamente al azar con arreglo factorial 2x5 con mediciones repetidas. Se observaron interacciones entre tipo de levadura x tiempo de fermentación para los contenidos de MS, PC, DVIVMS, FDN, FDA y L (P < 0.05. De acuerdo con los resultados obtenidos, las mejores características nutritivas en el nopal fermentado se obtuvieron a las 48 y 96 h de fermentación con S. cerevisiae y K. marxianus respectivamente.

  15. The properties of Kluyveromyces lactis for the production of D ...

    African Journals Online (AJOL)

    Production of D-arabitol from lactose by Kluyveromyces lactis NBRC 1903 was investigated to make a solution for utilization of whey. It turned out that initial concentration of yeast extract, working volume and initial cell mass concentration are important factors in D-arabitol production from lactose by this strain.

  16. The properties of Kluyveromyces lactis for the production of D ...

    African Journals Online (AJOL)

    USER

    2010-08-02

    Aug 2, 2010 ... Production of D-arabitol from lactose by Kluyveromyces lactis NBRC 1903 was investigated to make a solution for ... lactose and are characterized by high biological oxygen demand ... to calculate cell mass concentration (X). One unit of .... cultures, time required for the complete conversion of lactose in ...

  17. 21 CFR 184.1388 - Lactase enzyme preparation from Kluyveromyces lactis.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Lactase enzyme preparation from Kluyveromyces... GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS § 184.1388 Lactase enzyme preparation from Kluyveromyces lactis. (a) This enzyme preparation is derived from the nonpathogenic...

  18. Kluyveromyces marxianus and Saccharomyces boulardii Induce Distinct Levels of Dendritic Cell Cytokine Secretion and Significantly Different T Cell Responses In Vitro

    NARCIS (Netherlands)

    Smith, Ida M; Baker, Adam; Christensen, Jeffrey E; Boekhout, Teun; Frøkiær, Hanne; Arneborg, Nils; Jespersen, Lene

    2016-01-01

    Interactions between members of the intestinal microbiota and the mucosal immune system can significantly impact human health, and in this context, fungi and food-related yeasts are known to influence intestinal inflammation through direct interactions with specialized immune cells in vivo. The aim

  19. Melanin determination by high performance liquid chromatography (HPLC) for K. marxianus

    Science.gov (United States)

    Ultraviolet light (UV) mutated K. marxianus was found to turn dark brown during a growth assay. This brown color was hypothesized to be melanin overproduction influenced by the UV exposure. Cell cultures were oxidized and HPLC analyzed to determine melanin concentrations. The resulting melanin con...

  20. Batch cultivation of kluyveromyces fragilis in cheese whey

    Energy Technology Data Exchange (ETDEWEB)

    Beausejour, D; Leduy, A; Ramalho, R S

    1981-08-01

    Kluyveromyces fragilis was cultivated batchwise in an open pond rectangular bioreactor at 30 degrees Centigrade, 2vvm of aeration, under non-sterile conditions and uncontrolled pH. The culture medium contained 7% cheese whey powder, 0.25% KH/sub 2/PO/sub 4/, 0.5% (NH/sub 4/)/sub 2/SO/sub 4/ and was adjusted to an initial pH of 4.0 with phosphoric acid. The lactose was almost completely consumed after 16 hours and COD reduction attained 80% after 64 hours. The maximum suspended solids concentration obtained was 11.7 g/L. The cheese whey which had initially low protein and high lactose contents was converted by this system into a high protein and low lactose carbohydrate product. (Refs. 26).

  1. Batch cultivation of kluyveromyces fragilis in cheese whey

    Energy Technology Data Exchange (ETDEWEB)

    Beausejour, D; Leduy, A; Ramalho, R S

    1981-01-01

    Kluyveromyces fragilis was cultivated batchwise in an open pond rectangular bioreactor at 30 degrees Celcius with aeration, under non-sterile conditions and uncontrolled pH. The culture medium contained 7% cheese whey powder, 0.25% KH2PO4, and 0.5% (NH4)2SO4 and was adjusted to an initial pH of 4.0 with H3PO4. The lactose was almost completely consumed after 16 hours and COD reduction attained 80% after 64 hours. The maximum suspended solids concentration obtained was 11.7 g/L. The cheese whey which had initially low protein and high lactose contents was converted by this system into a high protein and low lactose carbohydrate product.

  2. A Preliminary Study of Europium Uptake by Yeast Cells. The Case of Kluveromyces Marxianus

    International Nuclear Information System (INIS)

    Anagnostopoulos, V.; Symeopoulos, B.

    2008-01-01

    The objective of the present work is an exploration of a cost effective recovery of lanthanides, either for minimizing the industrial processes losses, or for reasons related to Radioactive Waste Management. Specifically, the uptake of europium from aqueous solutions by Kluveromyces marxianus cells was studied. Moreover, this biotechnological approach turns out to be environmental friendly, considering that cells of Kluveromyces marxianus are readily available as wastes from food fermentation industries. Europium [ 152 Eu+ 154 Eu]-labelled solutions were used providing better accuracy and reproducibility of measurements, mainly in low concentration range. The effect of pH, contact time and europium initial concentration were investigated. Adsorption data were fitted to Langmuir and Freundlich sorption models and Scatchard plots were used to reveal the existence of at least two types of binding sites

  3. Isolation of a Kluyveromyces fragilis derepressed mutant hyperproducer of inulinase for ethanol production from Jerusalem artichoke

    Energy Technology Data Exchange (ETDEWEB)

    Bourgi, J.; Guirand, J.P.; Galzy, P.

    1986-01-01

    A paritally derepressed mutant of Kluyveromyces fragilis showing hyperproduction of inulinase was isolated by means of ethylmethanesulfonate mutation followed by a 2-deoxyglucose selection. This mutant is suitable for the fermentation of inulin and Jerusalem artichoke extracts containing large amounts of inulin high polyfructosans type (early extracts).

  4. Study of the transgalactosylation activity of ß-galactosidase from a new strain Kluyveromyces lactis 3

    Directory of Open Access Journals (Sweden)

    ILIA ILIEV

    2012-01-01

    Full Text Available Beta-galactosidase (EC.3.2.1.23 is an important enzyme industrially used for the hydrolysis of lactose from milk and milk whey for several applications. Lately, the importance of this enzyme was enhanced by its galactosyltransferase activity, which is responsible for synthesis of transgalactosylated oligosaccharides that act as prebiotics with several beneficial effects on the consumers. ß-Galactosidase production by Kluyveromyces lactis 3 was studied in shake flask culture. The highest enzymatic activity was obtained at 10-th hour of the fermentation. The optimum temperature for transferase activity was 50°C. When incubated with 30% lactose in 50 mM phosphate buffer (pH 6.0 the enzyme can synthesize up to 41% galacto-oligosaccharides (GalOS. β-Galactosidase from strain Kluyveromyces lactis 3 produces mainly oligosaccharides with degree of polymerization (DP 6 at 40°C and with DP 3 at 50°C.

  5. Crystallization and preliminary X-ray crystallographic analysis of β-galactosidase from Kluyveromyces lactis

    International Nuclear Information System (INIS)

    Pereira-Rodríguez, Ángel; Fernández-Leiro, Rafael; González Siso, M. Isabel; Cerdán, M. Esperanza; Becerra, Manuel; Sanz-Aparicio, Julia

    2010-01-01

    β-Galactosidase from K. lactis has been expressed in S. cerevisiae, purified by affinity chromatography and crystallized in its native form. β-Galactosidase from Kluyveromyces lactis catalyses the hydrolysis of the β-galactosidic linkage in lactose. Owing to its many industrial applications, the biotechnological potential of this enzyme is substantial. This protein has been expressed in yeast and purified for crystallization trials. However, optimization of the best crystallization conditions yielded crystals with poor diffraction quality that precluded further structural studies. Finally, the crystal quality was improved using the streak-seeding technique and a complete diffraction data set was collected at 2.8 Å resolution

  6. Use of continuous lactose fermentation for ethanol production by Kluveromyces marxianus for verification and extension of a biochemically structured model

    DEFF Research Database (Denmark)

    Sansonetti, S.; Hobley, Timothy John; Curcio, S.

    2013-01-01

    A biochemically structured model has been developed to describe the continuous fermentation of lactose to ethanol by Kluveromyces marxianus and allowed metabolic coefficients to be determined. Anaerobic lactose-limited chemostat fermentations at different dilution rates (0.02 – 0.35 h-1) were...... performed. Species specific rates of consumption/formation, as well as yield coefficients were determined. Ethanol yield (0.655 C-mol ethanol*C-mol lactose-1) was as high as 98 % of theoretical. The modeling procedure allowed calculation of maintenance coefficients for lactose consumption and ethanol...

  7. Kluyveromyces aestuarii, a potential environmental quality indicator yeast for mangroves in the State of Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    F.V Araujo

    2011-09-01

    Full Text Available Kluyveromyces aestuarii was found in sediments from 7 of 8 mangroves in Rio de Janeiro; and absent only at one site with heavy plastic bag pollution. Its presence suggests influence in other habitats from a mangrove and its absence in a mangrove suggests some non-fecal pollution or other habitat alteration.

  8. Qualidade protéica do soro de leite fermentado pela levedura Kluyveromyces fragilis

    OpenAIRE

    Silva,Caio Abércio da; Hernan-Gomez,Raul Castro

    2000-01-01

    O soro de leite fermentado pela levedura Kluyveromyces fragilis, após secagem em spray drier, foi submetido à avaliação da qualidade protéica através de uma análise aminoacídica e de um estudo biológico pelos métodos: Relação da Eficiência Protéica (PER), Relação da Eficiência Líquida da Proteína (NPR) e Utilização Líquida da Proteína (NPU). Na análise aminoacídica, foram utilizadas como comparativo a composição de aminoácidos das proteínas padrão do ovo e da FAO. Os resultados indicaram um a...

  9. Ecosystème fromager : de l'étude du métabolisme du soufre chez Kluyveromyces lactis et Yarrowia lipolytica à l'interaction entre Kluyveromyces lactis et Brevibacterium aurantiacum

    OpenAIRE

    Hébert , Agnès

    2010-01-01

    Sulphur metabolism, which has a central role in the cell, is also important during the manufacturing of smear ripened cheeses. The cheese ecosystem degrades sulphur aminoacids, producing volatile sulphur compounds (VSCs) indispensable for the flavour of these products. We studied sulphur metabolism in two cheese-ripening microorganisms, the hemiascomycetous yeasts Kluyveromyces lactis and Yarrowia lipolytica. The in silico analysis of the phylum of hemiascomycetes gave us for the first time a...

  10. Ecosystème fromager : de l'étude du métabolisme du soufre chez Kluyveromyces lactis et Yarrowia lipolytica à l'interaction entre Kluyveromyces lactis et Brevibacterium aurantiacum

    OpenAIRE

    Hebert , Agnès

    2010-01-01

    Sulphur metabolism, which has a central role in the cell, is also important during the manufacturing of smear ripened cheeses. The cheese ecosystem degrades sulphur amino acids, producing volatile sulphur compounds (VSCs) indispensable for the flavour of these products. We studied sulphur metabolism in two cheese-ripening microorganisms, the hemiascomycetous yeasts Kluyveromyces lactis and Yarrowia lipolytica. The in silico analysis of the phylum of hemiascomycetes gave us for the first time ...

  11. The major facilitator superfamily transporter Knq1p modulates boron homeostasis in Kluyveromyces lactis.

    Science.gov (United States)

    Svrbicka, Alexandra; Toth Hervay, Nora; Gbelska, Yvetta

    2016-03-01

    Boron is an essential micronutrient for living cells, yet its excess causes toxicity. To date, the mechanisms of boron toxicity are poorly understood. Recently, the ScATR1 gene has been identified encoding the main boron efflux pump in Saccharomyces cerevisiae. In this study, we analyzed the ScATR1 ortholog in Kluyveromyces lactis--the KNQ1 gene, to understand whether it participates in boron stress tolerance. We found that the KNQ1 gene, encoding a permease belonging to the major facilitator superfamily, is required for K. lactis boron tolerance. Deletion of the KNQ1 gene led to boron sensitivity and its overexpression increased K. lactis boron tolerance. The KNQ1 expression was induced by boron and the intracellular boron concentration was controlled by Knq1p. The KNQ1 promoter contains two putative binding motifs for the AP-1-like transcription factor KlYap1p playing a central role in oxidative stress defense. Our results indicate that the induction of the KNQ1 expression requires the presence of KlYap1p and that Knq1p like its ortholog ScAtr1p in S. cerevisiae functions as a boron efflux pump providing boron resistance in K. lactis.

  12. Statistical investigation of Kluyveromyces lactis cells permeabilization with ethanol by response surface methodology.

    Science.gov (United States)

    de Faria, Janaína T; Rocha, Pollyana F; Converti, Attilio; Passos, Flávia M L; Minim, Luis A; Sampaio, Fábio C

    2013-12-01

    The aim of our study was to select the optimal operating conditions to permeabilize Kluyveromyces lactis cells using ethanol as a solvent as an alternative to cell disruption and extraction. Cell permeabilization was carried out by a non-mechanical method consisting of chemical treatment with ethanol, and the results were expressed as β-galactosidase activity. Experiments were conducted under different conditions of ethanol concentration, treatment time and temperature according to a central composite rotatable design (CCRD), and the collected results were then worked out by response surface methodology (RSM). Cell permeabilization was improved by an increase in ethanol concentration and simultaneous decreases in the incubation temperature and treatment time. Such an approach allowed us to identify an optimal range of the independent variables within which the β-galactosidase activity was optimized. A maximum permeabilization of 2,816 mmol L(-1) oNP min(-1) g(-1) was obtained by treating cells with 75.0% v/v of ethanol at 20.0 °C for 15.0 min. The proposed methodology resulted to be effective and suited for K. lactis cells permeabilization at a lab-scale and promises to be of possible interest for future applications mainly in the food industry.

  13. Synthesis of Galactosyl Mannitol Derivative Using β-Galactosidase from Kluyveromyces lactis

    Directory of Open Access Journals (Sweden)

    Klewicki Robert

    2017-03-01

    Full Text Available The purpose of the study was to identify the influence of reactive mixture concentration (23–48 g/100 mL, pH (6.5–9.0, presence of NaCl (0.05–0.25 mol/L and enzyme dose (2850–28,500 LAU/100 g of lactose on the synthesis of galactosyl mannitol derivative using β-galactosidase from Kluyveromyces lactis. The use of the enzyme dose ranging from 2850 to 11,400 LAU/100 g lactose allowed obtaining gal-mannitol at the level of 21.8% total saccharides; higher doses intensified product decomposition. An increase in the concentration of the reactive mixture had a positive impact on the quantity of gal-mannitol obtained every single time, i.e. 4.39 g were obtained from 100 mL of a 23 g/100 mL solution and over 10 g were obtained from a 48 g/100 mL solution. A relatively low increase in product quantity (by ca. 5% occurred after the pH was increased from 6.5 to 9.0. The use of NaCl rendered better results. An increase in the maximum content of gal-mannitol in the total sugar by 12.8% was observed at the concentration of 0.25 mol/L.

  14. Purification of microbial b-galactosidase from Kluyveromyces fragilis by bioaffinity partitioning Purificação de b-galactosidase de Kluyveromyces fragilis por partição por bioafinidade

    Directory of Open Access Journals (Sweden)

    Maria Estela da Silva

    1999-12-01

    Full Text Available This work investigated the partitioning of b-galactosidase from Kluyveromyces fragilis in aqueous two-phase systems (ATPS by bioaffinity. PEG 4000 was chemically activated with thresyl chloride, and the biospecific ligand p-aminophenyl 1-thio-b-D-galactopyranoside (APGP was attached to the activated PEG 4000. A new two-step method for extraction and purification of the enzyme b-galactosidase from Kluyveromyces fragilis was developed. In the first step, a system composed of 6% PEG 4000-APGP and 8% dextran 505 was used, where b-galactosidase was strongly partitioned to the top phase (K = 2,330. In the second step, a system formed of 13% PEG-APGP and 9% phosphate salt was used to revert the value of the partition coefficient of b-galactosidase (K = 2 x 10-5 in order to provide the purification and recovery of 39% of the enzyme in the bottom salt-rich phase.Foi desenvolvido um método novo de extração e purificação da ß-galactosidase de Kluyveromyces fragilis em sistema de duas fases aquosas (SDFA. PEG 4000 foi ativado quimicamente com cloreto de tresila e o ligante bioespecífico p-aminofenil-ß-D-tiogalactopiranosídeo (APGP foi acoplado ao PEG 4000 ativado. Na primeira etapa foi usado um sistema composto de 6% PEG-APGP e 8% dextrana 505, onde a partição da ß-galactosidase ocorreu na fase superior (K = 2.330. Na segunda etapa foi usado um sistema composto por 13% PEG-APGP e 9% fosfato para reverter o valor do coeficiente de partição da ß-galactosidase (K = 2,2 x 10-5, obtendo-se recuperação de 39% da enzima na fase salina.

  15. Toxicity of nalidixic acid on candida albicans, Saccharomyces cerevisiae, and Kluyveromyces lactis.

    Science.gov (United States)

    Sobieski, R J; Brewer, A R

    1976-03-01

    The antibacterial drug nalidixic acid (Nal) can suppress the growth of Candida albicans at levels of the drug normally found in urine. Growth suppression increases as drug levels are increased, and Nal also causes a similar proportional inhibition of the synthesis of all cellular macromolecules. However, growth temperature (25 versus 37 C) and the divalent cations Mg(2+) and Mn(2+) can increase C. albicans resistance to Nal. Also, nitrogen depletion of Candida shows that Nal-treated and untreated cells exhibit no difference in leucine uptake during readaptation to nitrogen. In Nal-treated, nitrogen-starved cells, ribonucleic acid and deoxyribonucleic acid (DNA) biosynthesis are less affected than in unstarved Nal-treated cells, but of the two nucleic acids DNA synthesis is the most affected. Nal-resistant strains of C. albicans exhibit a slight toxicity for macromolecular synthesis. Nal treatment of a synchronized population of Saccharomyces cerevisiae results in an increase in the culture mean doubling time of, at most, 20%, but Nal causes the loss of synchronous cell division. With a synchronized population of Kluyveromyces lactis, Nal causes an increase in the mean doubling time of upwards of 300%, with synchrony of cell division being maintained. It is known that S. cerevisiae asynchronously synthesizes mitochondrial DNA during the cell cycle, whereas with K. lactis it is synchronous. Thus, with C. albicans Nal toxicity is dependent both on the dose and the physiological state of the cell. Furthermore, Nal inhibits growth of yeast with synchronous mitochondrial DNA synthesis more adversely than yeast with asynchronous mitochondrial DNA synthesis.

  16. Immobilization of β-galactosidase from Kluyveromyces lactis onto polymeric membrane surfaces: effect of surface characteristics.

    Science.gov (United States)

    Güleç, Hacı Ali

    2013-04-01

    The aim of this study was to investigate the effects of surface characteristics of plain and plasma modified cellulose acetate (CA) membranes on the immobilization yield of β-galactosidases from Kluyveromyces lactis (KLG) and its galacto-oligosaccharide (GOS) yield, respectively. Low pressure plasma treatments involving oxygen plasma activation, plasma polymerization (PlsP) of ethylenediamine (EDA) and PlsP of 2-mercaptoethanol were used to modify plain CA membrane surfaces. KLG enzyme was immobilized onto plain and oxygen plasma treated membrane surfaces by simple adsorption. Oxygen plasma activation increased the hydrophylicity of CA membrane surfaces and it improved the immobilization yield of the enzyme by 42%. KLG enzyme was also immobilized onto CA membrane surfaces through amino groups created by PlsP of EDA via covalent binding. Plasma action at 60W plasma power and 15 min. exposure time improved the amount of membrane bounded enzyme by 3.5-fold. The enrichment of the amount of amino groups via polyethyleneimine (PEI) addition enhanced this increase from 3.5-fold to 4.5-fold. Although high enzyme loading was achived (65-83%), both of the methods dramatically decreased the enzyme activity (11-12%) and GOS yield due to probably negative effects of active amino groups. KLG enzyme was more effectively immobilized onto thiolated CA membrane surface created by PlsP of 2-mercaptoethanol with high immobilization yield (70%) and especially high enzyme activity (46%). Immobilized enzymes on the CA membranes treated by PlsP were successively reutilized for 5-8 cycles at 25°C and enzymatic derivatives retained approximately 75-80% of their initial activites at the end of the reactions. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Developing a xylanase XYNZG from Plectosphaerella cucumerina for baking by heterologously expressed in Kluyveromyces lactis.

    Science.gov (United States)

    Zhan, Fei Xiang; Wang, Qin Hong; Jiang, Si Jing; Zhou, Yu Ling; Zhang, Gui Min; Ma, Yan He

    2014-12-16

    Xylanase can replace chemical additives to improve the volume and sensory properties of bread in the baking. Suitable baking xylanase with improved yield will promote the application of xylanase in baking industry. The xylanase XYNZG from the Plectosphaerella cucumerina has been previously characterized by heterologous expression in Pichia pastoris. However, P. pastoris is not a suitable host for xylanase to be used in the baking process since P. pastoris does not have GRAS (Generally Regarded As Safe) status and requires large methanol supplement during the fermentation in most conditions, which is not allowed to be used in the food industry. Kluyveromyces lactis, as another yeast expression host, has a GRAS status, which has been successfully used in food and feed applications. No previous work has been reported concerning the heterologous expression of xylanase gene xynZG in K. lactis with an aim for application in baking. The xylanase gene xynZG from the P. cucumerina was heterologously expressed in K. lactis. The recombinant protein XYNZG in K. lactis presented an approximately 19 kDa band on SDS-PAGE and zymograms analysis. Transformant with the highest halo on the plate containing the RBB-xylan (Remazol Brilliant Blue-xylan) was selected for the flask fermentation in different media. The results indicated that the highest activity of 115 U/ml at 72 h was obtained with the YLPU medium. The mass spectrometry analysis suggested that the hydrolytic products of xylan by XYNZG were mainly xylobiose and xylotriose. The results of baking trials indicated that the addition of XYNZG could reduce the kneading time of dough, increase the volume of bread, improve the texture, and have more positive effects on the sensory properties of bread. Xylanase XYNZG is successfully expressed in K. lactis, which exhibits the highest activity among the published reports of the xylanase expression in K. lactis. The recombinant XYNZG can be used to improve the volume and sensory

  18. Secretion and properties of a hybrid Kluyveromyces lactis-Aspergillus niger β-galactosidase

    Directory of Open Access Journals (Sweden)

    Becerra Manuel

    2006-12-01

    Full Text Available Abstract Background The β-galactosidase from Kluyveromyces lactis is a protein of outstanding biotechnological interest in the food industry and milk whey reutilization. However, due to its intracellular nature, its industrial production is limited by the high cost associated to extraction and downstream processing. The yeast-system is an attractive method for producing many heterologous proteins. The addition of a secretory signal in the recombinant protein is the method of choice to sort it out of the cell, although biotechnological success is not guaranteed. The cell wall acting as a molecular sieve to large molecules, culture conditions and structural determinants present in the protein, all have a decisive role in the overall process. Protein engineering, combining domains of related proteins, is an alternative to take into account when the task is difficult. In this work, we have constructed and analyzed two hybrid proteins from the β-galactosidase of K. lactis, intracellular, and its Aspergillus niger homologue that is extracellular. In both, a heterologous signal peptide for secretion was also included at the N-terminus of the recombinant proteins. One of the hybrid proteins obtained has interesting properties for its biotechnological utilization. Results The highest levels of intracellular and extracellular β-galactosidase were obtained when the segment corresponding to the five domain of K. lactis β-galactosidase was replaced by the corresponding five domain of the A. niger β-galactosidase. Taking into account that this replacement may affect other parameters related to the activity or the stability of the hybrid protein, a thoroughly study was performed. Both pH (6.5 and temperature (40°C for optimum activity differ from values obtained with the native proteins. The stability was higher than the corresponding to the β-galactosidase of K. lactis and, unlike this, the activity of the hybrid protein was increased by the presence

  19. Ethanol fermentation from molasses at high temperature by thermotolerant yeast Kluyveromyces sp. IIPE453 and energy assessment for recovery.

    Science.gov (United States)

    Dasgupta, Diptarka; Ghosh, Prasenjit; Ghosh, Debashish; Suman, Sunil Kumar; Khan, Rashmi; Agrawal, Deepti; Adhikari, Dilip K

    2014-10-01

    High temperature ethanol fermentation from sugarcane molasses B using thermophilic Crabtree-positive yeast Kluyveromyces sp. IIPE453 was carried out in batch bioreactor system. Strain was found to have a maximum specific ethanol productivity of 0.688 g/g/h with 92 % theoretical ethanol yield. Aeration and initial sugar concentration were tuning parameters to regulate metabolic pathways of the strain for either cell mass or higher ethanol production during growth with an optimum sugar to cell ratio 33:1 requisite for fermentation. An assessment of ethanol recovery from fermentation broth via simulation study illustrated that distillation-based conventional recovery was significantly better in terms of energy efficiency and overall mass recovery in comparison to coupled solvent extraction-azeotropic distillation technique for the same.

  20. Kluyveromyces lactis β-galactosidase immobilization in calcium alginate spheres and gelatin for hydrolysis of cheese whey lactose

    Directory of Open Access Journals (Sweden)

    Ana Paula Mörschbächer

    2016-05-01

    Full Text Available ABSTRACT: One of the greatest challenges for dairy industries is the correct destination of all the whey generated during cheese making, considering its high impact, the large volume created, and its technological potential. Enzymatic hydrolysis of cheese whey lactose is a biotechnological alternative. However, one of the limiting factors of its use is the relatively high cost of the enzymes, which could be lowered with the immobilization of these biocatalysts. Considering this context, the objective of this research was to evaluate the commercial Kluyveromyces lactis β-galactosidase enzyme immobilized in calcium alginate spheres and gelatin, using glutaraldehyde and concanavalin A (ConA as modifying agents in the hydrolysis of cheese whey lactose process. Results have shown that the enzyme encapsulation complexed with ConA in alginate-gelatin spheres, without glutaraldehyde in the immobilization support, has significantly increased the hydrolysis of lactose rate, achieving a maximum conversion of 72%.

  1. Cloning, production, and functional expression of the bacteriocin enterocin A, produced by Enterococcus faecium T136, by the yeasts Pichia pastoris, Kluyveromyces lactis, Hansenula polymorpha, and Arxula adeninivorans.

    Science.gov (United States)

    Borrero, Juan; Kunze, Gotthard; Jiménez, Juan J; Böer, Erik; Gútiez, Loreto; Herranz, Carmen; Cintas, Luis M; Hernández, Pablo E

    2012-08-01

    The bacteriocin enterocin A (EntA) produced by Enterococcus faecium T136 has been successfully cloned and produced by the yeasts Pichia pastoris X-33EA, Kluyveromyces lactis GG799EA, Hansenula polymorpha KL8-1EA, and Arxula adeninivorans G1212EA. Moreover, P. pastoris X-33EA and K. lactis GG799EA produced EntA in larger amounts and with higher antimicrobial and specific antimicrobial activities than the EntA produced by E. faecium T136.

  2. Hydrolysis of lactose by β-galactosidase from Kluyveromyces fragilis: characterization of the enzyme Hidrólise da lactose pela β-galactosidase de Kluyveromyces fragilis: caracterização da enzima

    Directory of Open Access Journals (Sweden)

    Graciette Matioli

    2002-03-01

    Full Text Available The β-galactosidase enzyme from Kluyveromyces fragilis was characterized in the soluble form using lactose 5% w/v found in skimmed powdered milk as substrate. Enzyme diluted 50 times hydrolyzed the lactose in batch reactor of 50 mL capacity. Enzyme activity and its activation energy were determined as a function of temperature and pH. Temperature ranged from 20 to 55ºC and pH from 5.5 to 8.0. Activation energy was 9.50 kcal/mol. The energy of deactivation was 33.74 kcal/mol. Although the enzyme presented a high specific activity at 45ºC and pH 6.5 (3.312 U/mg protein, values indicate that the best use of the enzymatic activity occur at 40ºC or below, with half-life higher than 12 hours. The activation energy increased proportionally to pH increase. Therefore, the activation energy depends on pH and varies according to the origin of the enzyme.A enzima β-galactosidase de Kluyveromyces fragilis foi caracterizada na forma solúvel, utilizando como substrato, lactose 5% p/v presente no leite em pó desengordurado. A enzima, diluída 50 vezes, hidrolisou a lactose em reator batelada de 50 ml de capacidade. A atividade da enzima e sua energia de ativação foram determinadas em função da temperatura e pH. A faixa de temperatura analisada foi de 20 a 55ºC e de pH de 5,5 a 8,0. A energia de ativação foi de 9,50 kcal/mol. A energia de desativação foi de 33,74 kcal/mol. Embora a enzima tenha apresentado uma atividade específica alta a 45ºC e pH 6,5 (3,312 U/mg proteína, os valores obtidos indicam que o melhor aproveitamento da atividade enzimática se dá a 40ºC ou abaixo, com um tempo de meia-vida superior a 12 horas. A energia de ativação aumentou proporcionalmente com o aumento de pH. Portanto, a energia de ativação depende diretamente do pH da solução e varia com a origem da enzima.

  3. The Deletion of the Succinate Dehydrogenase Gene KlSDH1 in Kluyveromyces lactis Does Not Lead to Respiratory Deficiency

    Science.gov (United States)

    Saliola, Michele; Bartoccioni, Paola Chiara; De Maria, Ilaria; Lodi, Tiziana; Falcone, Claudio

    2004-01-01

    We have isolated a Kluyveromyces lactis mutant unable to grow on all respiratory carbon sources with the exception of lactate. Functional complementation of this mutant led to the isolation of KlSDH1, the gene encoding the flavoprotein subunit of the succinate dehydrogenase (SDH) complex, which is essential for the aerobic utilization of carbon sources. Despite the high sequence conservation of the SDH genes in Saccharomyces cerevisiae and K. lactis, they do not have the same relevance in the metabolism of the two yeasts. In fact, unlike SDH1, KlSDH1 was highly expressed under both fermentative and nonfermentative conditions. In addition to this, but in contrast with S. cerevisiae, K. lactis strains lacking KlSDH1 were still able to grow in the presence of lactate. In these mutants, oxygen consumption was one-eighth that of the wild type in the presence of lactate and was normal with glucose and ethanol, indicating that the respiratory chain was fully functional. Northern analysis suggested that alternative pathway(s), which involves pyruvate decarboxylase and the glyoxylate cycle, could overcome the absence of SDH and allow (i) lactate utilization and (ii) the accumulation of succinate instead of ethanol during growth on glucose. PMID:15189981

  4. Improved ethanol tolerance of Saccharomyces cerevisiae in mixed cultures with Kluyveromyces lactis on high-sugar fermentation.

    Science.gov (United States)

    Yamaoka, Chizuru; Kurita, Osamu; Kubo, Tomoko

    2014-12-01

    The influence of non-Saccharomyces yeast, Kluyveromyces lactis, on metabolite formation and the ethanol tolerance of Saccharomyces cerevisiae in mixed cultures was examined on synthetic minimal medium containing 20% glucose. In the late stage of fermentation after the complete death of K. lactis, S. cerevisiae in mixed cultures was more ethanol-tolerant than that in pure culture. The chronological life span of S. cerevisiae was shorter in pure culture than mixed cultures. The yeast cells of the late stationary phase both in pure and mixed cultures had a low buoyant density with no significant difference in the non-quiescence state between both cultures. In mixed cultures, the glycerol contents increased and the alanine contents decreased when compared with the pure culture of S. cerevisiae. The distinctive intracellular amino acid pool concerning its amino acid concentrations and its amino acid composition was observed in yeast cells with different ethanol tolerance in the death phase. Co-cultivation of K. lactis seems to prompt S. cerevisiae to be ethanol tolerant by forming opportune metabolites such as glycerol and alanine and/or changing the intracellular amino acid pool. Copyright © 2014 Elsevier GmbH. All rights reserved.

  5. Enzyme activity of β-galactosidase from Kluyveromyces lactis and Aspergillus oryzae on simulated conditions of human gastrointestinal system

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    Alessandra Bosso

    2015-09-01

    Full Text Available An alternative to relieve the symptoms of lactose intolerance is the intake of the enzyme β-galactosidase in pharmaceutical dosage forms. The ability of β-galactosidase produced by Kluyveromyces lactis and Aspergillus oryzae to hydrolyze lactose in simulated conditions of the human gastrointestinal tract was investigated. The experiment was carried out in the optimum temperature for each enzyme activity, 40 and 55°C, respectively, and at the normal human body temperature (37°C at concentrations of 1.5, 3.0, and 5.0 g/L (enzyme from A. oryzae or mL/L (enzyme from K. lactis. Both enzymes were completely inactivated under simulated gastric conditions (pH 2. When the enzymes were subjected to simulated small intestine conditions (pH 7.4, lactose hydrolysis has occurred, but at 37°C the percentage was lower than that under the optimal temperatures. At concentrations of 1.5, 3.0, and 5.0 mL/L the enzyme from K. lactis hydrolyzed 76.63%, 88.91% and 94.80% of lactose at 40°C, and 55.99%, 80.91% and 81.53% at 37°C, respectively. In contrast, the enzyme from A. oryzae hydrolyzed 7.11%, 16.18% and 21.29% at 55°C, and 8.4%, 11.85% and 16.43% at 37°C. It was observed that under simulated intestinal conditions, the enzyme from K. lactis was more effective on lactose hydrolysis as compared to the enzyme from A. oryzae. Considering the findings of this study, it is extremely necessary to use an enteric coating on β-galactosidase capsules so that this enzyme is released only in the small intestine, which is its site of action, thus not suffering the action of the stomach pH.Keywords: Lactase. Hydrolysis. Lactose intolerance. Gastrointestinal tract. RESUMOAtividade de β-galactosidase de Kluyveromyces lactis e Aspergillus oryzae, em condições simuladas do sistema gastrintestinal humanoUma das alternativas para amenizar os sintomas da intolerância à lactose é a ingestão de β-galactosidase em formas farmacêuticas. Neste trabalho avaliou-se a

  6. Reaction kinetics and galactooligosaccharide product profiles of the β-galactosidases from Bacillus circulans, Kluyveromyces lactis and Aspergillus oryzae.

    Science.gov (United States)

    Yin, Huifang; Bultema, Jelle B; Dijkhuizen, Lubbert; van Leeuwen, Sander S

    2017-06-15

    β-Galactosidase enzymes are used in the dairy industry to convert lactose into galactooligosaccharides (GOS) that are added to infant formula to mimic the molecular sizes and prebiotic functions of human milk oligosaccharides. Here we report a detailed analysis of the clearly different GOS profiles of the commercial β-galactosidases from Bacillus circulans, Kluyveromyces lactis and Aspergillus oryzae. Also the GOS yields of these enzymes differed, varying from 48.3% (B. circulans) to 34.9% (K. lactis), and 19.5% (A. oryzae). Their incubation with lactose plus the monosaccharides Gal or Glc resulted in altered GOS profiles. Experiments with 13 C 6 labelled Gal and Glc showed that both monosaccharides act as acceptor substrates in the transgalactosylation reactions. The data shows that the lactose isomers β-d-Galp-(1→2)-d-Glcp, β-d-Galp-(1→3)-d-Glcp and β-d-Galp-(1→6)-d-Glcp are formed from acceptor reactions with free Glc and not by rearrangement of Glc in the active site. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Síntese de galacto-oligossacarídeos a partir de lactose usando β-galactosidase comercial de Kluyveromyces lactis Synthesis of galactooligosaccharides from lactose using commercial β-galactosidase from Kluyveromyces lactis

    Directory of Open Access Journals (Sweden)

    Cristiane Reinaldo Lisboa

    2012-03-01

    Full Text Available O objetivo deste trabalho foi estudar a influência de parâmetros reacionais na obtenção via enzimática de galacto-oligossacarídeos (GOS, utilizando-se a enzima comercial β-galactosidase de Kluyveromyces lactis (Lactozym® 3000 L, tendo como substrato a lactose. Foi proposto um planejamento experimental 2³, verificando a influência da temperatura (30 a 40 °C, da concentração de lactose (200 a 400 mg.mL-1 e da concentração de enzima (5 a 10 U.mL-1 no desempenho da reação enzimática. Os ensaios foram conduzidos a 180 rpm e pH 7,0 (tampão fosfato de sódio 0,1 M. A enzima Lactozym® 3000 L apresentou atividade de transgalactosilação, tendo sido atingido rendimento do processo igual a 41,9% e concentração de GOS de 167,5 mg.mL-1 no sistema reacional composto por 400 mg.mL-1 de lactose e 5 U.mL-1 de enzima a 30 °C em 14 h de reação. Nessa condição, a conversão de lactose foi de 65,0%. Maior concentração de lactose foi favorável ao mecanismo de transgalactosilação, enquanto que, em menores concentrações, o mecanismo hidrolítico predominou.The main goal of this work was to study the influence of the reaction parameters on the enzymatic production of galactooligosaccharides (GOS using the commercial β-galactosidase from Kluyveromyces lactis (Lactozym® 3000 L and lactose as the substrate. A 2³ experimental design was proposed, verifying the influence of the temperature (30 to 40 °C, lactose concentration (200 to 400 mg.mL-1 and enzyme concentration (5 to 10 U.mL-1 on the performance of the enzymatic reaction. The assays were carried out at 180 rpm and pH 7.0 (0.1 M sodium phosphate buffer. The enzyme Lactozym® 3000 L presented transgalactosylation activity, reaching a yield of 41.9% and GOS concentration of 167.5 mg.mL-1 in a reaction system composed of 400 mg.mL-1 of lactose and 5 U.mL-1 of enzyme at 30 °C and 14 h of reaction. Under these conditions the lactose conversion was 65.0%. Higher lactose concentrations

  8. Perdeuteration and methyl-selective 1H, 13C-labeling by using a Kluyveromyces lactis expression system

    International Nuclear Information System (INIS)

    Miyazawa-Onami, Mayumi; Takeuchi, Koh; Takano, Toshiaki; Sugiki, Toshihiko; Shimada, Ichio; Takahashi, Hideo

    2013-01-01

    The production of stable isotope-labeled proteins is critical in structural analyses of large molecular weight proteins using NMR. Although prokaryotic expression systems using Escherichia coli have been widely used for this purpose, yeast strains have also been useful for the expression of functional eukaryotic proteins. Recently, we reported a cost-effective stable isotope-labeled protein expression using the hemiascomycete yeast Kluyveromyces lactis (K. lactis), which allow us to express exogenous proteins at costs comparable to prokaryotic expression systems. Here, we report the successful production of highly deuterated (>90 %) protein in the K. lactis system. We also examined the methyl-selective 1 H, 13 C-labeling of Ile, Leu, and Val residues using commonly used amino acid precursors. The efficiency of 1 H- 13 C-incorporation varied significantly based on the amino acid. Although a high level of 1 H- 13 C-incorporation was observed for the Ile δ1 position, 1 H, 13 C-labeling rates of Val and Leu methyl groups were limited due to the mitochondrial localization of enzymes involved in amino acid biosynthesis and the lack of transporters for α-ketoisovalerate in the mitochondrial membrane. In line with this notion, the co-expression with branched-chain-amino-acid aminotransferase in the cytosol significantly improved the incorporation rates of amino acid precursors. Although it would be less cost-effective, addition of 13 C-labeled valine can circumvent problems associated with precursors and achieve high level 1 H, 13 C-labeling of Val and Leu. Taken together, the K. lactis system would be a good alternative for expressing large eukaryotic proteins that need deuteration and/or the methyl-selective 1 H, 13 C-labeling for the sensitive detection of NMR resonances

  9. Deletion of the Glucose-6-Phosphate Dehydrogenase Gene KlZWF1 Affects both Fermentative and Respiratory Metabolism in Kluyveromyces lactis▿

    Science.gov (United States)

    Saliola, Michele; Scappucci, Gina; De Maria, Ilaria; Lodi, Tiziana; Mancini, Patrizia; Falcone, Claudio

    2007-01-01

    In Kluyveromyces lactis, the pentose phosphate pathway is an alternative route for the dissimilation of glucose. The first enzyme of the pathway is the glucose-6-phosphate dehydrogenase (G6PDH), encoded by KlZWF1. We isolated this gene and examined its role. Like ZWF1 of Saccharomyces cerevisiae, KlZWF1 was constitutively expressed, and its deletion led to increased sensitivity to hydrogen peroxide on glucose, but unlike the case for S. cerevisiae, the Klzwf1Δ strain had a reduced biomass yield on fermentative carbon sources as well as on lactate and glycerol. In addition, the reduced yield on glucose was associated with low ethanol production and decreased oxygen consumption, indicating that this gene is required for both fermentation and respiration. On ethanol, however, the mutant showed an increased biomass yield. Moreover, on this substrate, wild-type cells showed an additional band of activity that might correspond to a dimeric form of G6PDH. The partial dimerization of the G6PDH tetramer on ethanol suggested the production of an NADPH excess that was negative for biomass yield. PMID:17085636

  10. Molecular analysis of UAS(E), a cis element containing stress response elements responsible for ethanol induction of the KlADH4 gene of Kluyveromyces lactis.

    Science.gov (United States)

    Mazzoni, C; Santori, F; Saliola, M; Falcone, C

    2000-01-01

    KlADH4 is a gene of Kluyveromyces lactis encoding a mitochondrial alcohol dehydrogenase activity, which is specifically induced by ethanol and insensitive to glucose repression. In this work, we report the molecular analysis of UAS(E), an element of the KlADH4 promoter which is essential for the induction of KlADH4 in the presence of ethanol. UAS(E) contains five stress response elements (STREs), which have been found in many genes of Saccharomyces cerevisiae involved in the response of cells to conditions of stress. Whereas KlADH4 is not responsive to stress conditions, the STREs present in UAS(E) seem to play a key role in the induction of the gene by ethanol, a situation that has not been observed in the related yeast S. cerevisiae. Gel retardation experiments showed that STREs in the KlADH4 promoter can bind factor(s) under non-inducing conditions. Moreover, we observed that the RAP1 binding site present in UAS(E) binds KlRap1p.

  11. Oxygen-Dependent Transcriptional Regulator Hap1p Limits Glucose Uptake by Repressing the Expression of the Major Glucose Transporter Gene RAG1 in Kluyveromyces lactis▿

    Science.gov (United States)

    Bao, Wei-Guo; Guiard, Bernard; Fang, Zi-An; Donnini, Claudia; Gervais, Michel; Passos, Flavia M. Lopes; Ferrero, Iliana; Fukuhara, Hiroshi; Bolotin-Fukuhara, Monique

    2008-01-01

    The HAP1 (CYP1) gene product of Saccharomyces cerevisiae is known to regulate the transcription of many genes in response to oxygen availability. This response varies according to yeast species, probably reflecting the specific nature of their oxidative metabolism. It is suspected that a difference in the interaction of Hap1p with its target genes may explain some of the species-related variation in oxygen responses. As opposed to the fermentative S. cerevisiae, Kluyveromyces lactis is an aerobic yeast species which shows different oxygen responses. We examined the role of the HAP1-equivalent gene (KlHAP1) in K. lactis. KlHap1p showed a number of sequence features and some gene targets (such as KlCYC1) in common with its S. cerevisiae counterpart, and KlHAP1 was capable of complementing the hap1 mutation. However, the KlHAP1 disruptant showed temperature-sensitive growth on glucose, especially at low glucose concentrations. At normal temperature, 28°C, the mutant grew well, the colony size being even greater than that of the wild type. The most striking observation was that KlHap1p repressed the expression of the major glucose transporter gene RAG1 and reduced the glucose uptake rate. This suggested an involvement of KlHap1p in the regulation of glycolytic flux through the glucose transport system. The ΔKlhap1 mutant showed an increased ability to produce ethanol during aerobic growth, indicating a possible transformation of its physiological property to Crabtree positivity or partial Crabtree positivity. Dual roles of KlHap1p in activating respiration and repressing fermentation may be seen as a basis of the Crabtree-negative physiology of K. lactis. PMID:18806211

  12. Use of the KlADH3 promoter for the quantitative production of the murine PDE5A isoforms in the yeast Kluyveromyces lactis.

    Science.gov (United States)

    Cardarelli, Silvia; Giorgi, Mauro; Naro, Fabio; Malatesta, Francesco; Biagioni, Stefano; Saliola, Michele

    2017-09-22

    Phosphodiesterases (PDE) are a superfamily of enzymes that hydrolyse cyclic nucleotides (cAMP/cGMP), signal molecules in transduction pathways regulating crucial aspects of cell life. PDEs regulate the intensity and duration of the cyclic nucleotides signal modulating the downstream biological effect. Due to this critical role associated with the extensive distribution and multiplicity of isozymes, the 11 mammalian families (PDE1 to PDE11) constitute key therapeutic targets. PDE5, one of these cGMP-specific hydrolysing families, is the molecular target of several well known drugs used to treat erectile dysfunction and pulmonary hypertension. Kluyveromyces lactis, one of the few yeasts capable of utilizing lactose, is an attractive host alternative to Saccharomyces cerevisiae for heterologous protein production. Here we established K. lactis as a powerful host for the quantitative production of the murine PDE5 isoforms. Using the promoter of the highly expressed KlADH3 gene, multicopy plasmids were engineered to produce the native and recombinant Mus musculus PDE5 in K. lactis. Yeast cells produced large amounts of the purified A1, A2 and A3 isoforms displaying K m , V max and Sildenafil inhibition values similar to those of the native murine enzymes. PDE5 whose yield was nearly 1 mg/g wet weight biomass for all three isozymes (30 mg/L culture), is well tolerated by K. lactis cells without major growth deficiencies and interferences with the endogenous cAMP/cGMP signal transduction pathways. To our knowledge, this is the first time that the entire PDE5 isozymes family containing both regulatory and catalytic domains has been produced at high levels in a heterologous eukaryotic organism. K. lactis has been shown to be a very promising host platform for large scale production of mammalian PDEs for biochemical and structural studies and for the development of new specific PDE inhibitors for therapeutic applications in many pathologies.

  13. Use of synthetic genes for cloning, production and functional expression of the bacteriocins enterocin A and bacteriocin E 50-52 by Pichia pastoris and Kluyveromyces lactis.

    Science.gov (United States)

    Jiménez, Juan J; Borrero, Juan; Gútiez, Loreto; Arbulu, Sara; Herranz, Carmen; Cintas, Luis M; Hernández, Pablo E

    2014-06-01

    The use of synthetic genes may constitute a successful approach for the heterologous production and functional expression of bacterial antimicrobial peptides (bacteriocins) by recombinant yeasts. In this work, synthetic genes with adapted codon usage designed from the mature amino acid sequence of the bacteriocin enterocin A (EntA), produced by Enterococcus faecium T136, and the mature bacteriocin E 50-52 (BacE50-52), produced by E. faecium NRRL B-32746, were synthesized. The synthetic entA and bacE50-52 were cloned into the protein expression vectors pPICZαA and pKLAC2 for transformation of derived vectors into Pichia pastoris X-33 and Kluyveromyces lactis GG799, respectively. The recombinant vectors were linearized and transformed into competent cells selecting for P. pastoris X-33EAS (entA), P. pastoris X-33BE50-52S (bacE50-52), K. lactis GG799EAS (entA), and K. lactis GG799BE50-52S (bacE50-52). P. pastoris X-33EAS and K. lactis GG799EAS, but not P. pastoris X-33BE50-52S and K. lactis GG799BE50-52S, showed antimicrobial activity in their supernatants. However, purification of the supernatants of the producer yeasts permitted recovery of the bacteriocins EntA and BacE50-52. Both purified bacteriocins were active against Gram-positive bacteria such as Listeria monocytogenes but not against Gram-negative bacteria, including Campylobacter jejuni.

  14. Estabilidade operacional e cinética de hidrólise da lactose pela β-galactosidase de Kluyveromyces fragilis - DOI: 10.4025/actascihealthsci.v25i1.2244 Operational stability and kinetics of lactose hydrolysis by β-galactosidase from Kluyveromyces fragilis - DOI: 10.4025/actascihealthsci.v25i1.2244

    Directory of Open Access Journals (Sweden)

    Flávio Faria de Moraes

    2003-04-01

    Full Text Available A modelagem cinética da hidrólise da lactose e a estabilidade operacional da enzima β-galactosidase de Kluyveromyces fragilis foi determinada utilizando como substrato leite em pó desengordurado e reconstituído de modo a fornecer duas concentrações de lactose: 5% e 10% (p/v. Para a estabilidade operacional, ambas concentrações de lactose foram estudadas na presença e na ausência de tampão pH 6,5. A cada 40 minutos, foi determinada a atividade residual pelo método das velocidades iniciais. Os resultados experimentais mostraram que o tampão provoca inativação da enzima. Para soluções de lactose em água, a atividade residual decaiu apenas 15% em 6 horas e depois decresceu bruscamente. Na modelagem cinética, a reação de hidrólise foi conduzida a 40ºC/7 h, empregando-se concentrações de enzima equivalentes a 1500 e 8100 LAU/L. O modelo ajustado permitiu concluir que é necessário utilizar a quantidade de 3450 LAU/L da enzima para se obter a hidrólise de 70% a 80% da lactose do leite em duas a três horas de reação.The kinetic modeling of the lactose hydrolysis and the operational stability of the enzyme β-galactosidase of Kluyveromyces fragilis was determined using as substrate skimmed powdered milk, reconstituted in a way to supply two lactose concentrations: 5% and 10% (w/v. For the operational stability both lactose concentrations were studied in the presence and in the absence of the buffer pH 6.5. Every 40 minutes the residual activity was determined by the method of the initial velocities. The experimental results showed that the buffer leads to enzyme inactivation. However, for lactose solutions without buffer, the residual activity only declines 15% in 6 hours and later it decreases abruptly. In the kinetic modeling the hydrolysis reaction was led to 40ºC/7h, being used enzyme concentrations equivalent to 1500 and 8100 LAU/L. The adjusted model allowed us to conclude that it is necessary to use the quantity of

  15. Functional and Structural Characterization of Purine Nucleoside Phosphorylase from Kluyveromyces lactis and Its Potential Applications in Reducing Purine Content in Food.

    Science.gov (United States)

    Mahor, Durga; Priyanka, Anu; Prasad, Gandham S; Thakur, Krishan Gopal

    2016-01-01

    Consumption of foods and beverages with high purine content increases the risk of hyperuricemia, which causes gout and can lead to cardiovascular, renal, and other metabolic disorders. As patients often find dietary restrictions challenging, enzymatically lowering purine content in popular foods and beverages offers a safe and attractive strategy to control hyperuricemia. Here, we report structurally and functionally characterized purine nucleoside phosphorylase (PNP) from Kluyveromyces lactis (KlacPNP), a key enzyme involved in the purine degradation pathway. We report a 1.97 Å resolution crystal structure of homotrimeric KlacPNP with an intrinsically bound hypoxanthine in the active site. KlacPNP belongs to the nucleoside phosphorylase-I (NP-I) family, and it specifically utilizes 6-oxopurine substrates in the following order: inosine > guanosine > xanthosine, but is inactive towards adenosine. To engineer enzymes with broad substrate specificity, we created two point variants, KlacPNPN256D and KlacPNPN256E, by replacing the catalytically active Asn256 with Asp and Glu, respectively, based on structural and comparative sequence analysis. KlacPNPN256D not only displayed broad substrate specificity by utilizing both 6-oxopurines and 6-aminopurines in the order adenosine > inosine > xanthosine > guanosine, but also displayed reversal of substrate specificity. In contrast, KlacPNPN256E was highly specific to inosine and could not utilize other tested substrates. Beer consumption is associated with increased risk of developing gout, owing to its high purine content. Here, we demonstrate that KlacPNP and KlacPNPN256D could be used to catalyze a key reaction involved in lowering beer purine content. Biochemical properties of these enzymes such as activity across a wide pH range, optimum activity at about 25°C, and stability for months at about 8°C, make them suitable candidates for food and beverage industries. Since KlacPNPN256D has broad substrate specificity, a

  16. Identification and assessment of kefir yeast potential for sugar/ethanol-resistance

    Science.gov (United States)

    Miguel, M.G.C.P.; Cardoso, P.G.; Magalhães-Guedes, K.T.; Schwan, R.F.

    2013-01-01

    Biochemical and molecular analysis was used for identification of different kefir yeasts species from Brazil, Canada and the United States of America. The sugar/ethanol-resistant activity of the yeasts was evaluated. Saccharomyces cerevisiae and Kluyveromyces marxianus had the highest growth rates, suggesting biotechnological applications possible for these strains. PMID:24159292

  17. Use of starter cultures of lactic acid bacteria and yeasts as inoculum enrichment for the production of gowé, a sour beverage from Benin

    DEFF Research Database (Denmark)

    Vieira-Dalodé, G.; Madodé, Y.E.; Hounhouigan, J.

    2008-01-01

    Lactobacillus fermentum, Weissella confusa, Kluyveromyces marxianus and Pichia anomala, previously isolated during natural fermentation of traditional gowé, were tested as inoculum enrichment for controlled fermentation of gowé. The final product was subjected to chemical analysis and sensory eva...

  18. La regulación de la biosíntesis de hemo en Kluyveromyces lactis: regulación transcripcional de los genes KIHEM1, KlHEM12 y análisis comparativo de los factores reguladores Hap1p y Srb10p en levaduras.

    OpenAIRE

    Núñez-Naveira, Laura

    2011-01-01

    [Resumen] Kluyveromyces lactis es una levadura de elevado interés biotecnológico que se diferencia de la levadura tradicional de estudio Saccharomyces cerevisiae en diversos aspectos de su metabolismo. Mientras que en condiciones de aerobiosis y con glucosa como fuente de carbono K. lactis posee un metabolismo fundamentalmente respirativo, S. cervisiae lo tiene fermentativo en el mismo contexto. Estas diferencias metabólicas podrían ser el reflejo de una diferente regulación transcrip...

  19. Produção de protoplastos e lise da parede celular de leveduras utilizando β-1,3 glucanase Protoplasts production and yeast cell wall lysis using β-1,3 glucanase

    Directory of Open Access Journals (Sweden)

    Luciana Francisco Fleuri

    2010-06-01

    Full Text Available O presente trabalho visou a aplicação da β-1,3 glucanase lítica, obtida do microrganismo Cellulosimicrobium cellulans 191, na produção de protoplastos e na lise da parede celular de leveduras. A preparação bruta da enzima foi capaz de lisar as leveduras Kluyveromyces lodderi, Saccharomyces cerevisiae (Fleischmann e Itaiquara, S. cerevisiae KL-88, S. diastaticus NCYC 713, S. cerevisiae NCYC 1001, Candida glabrata NCYC 388, Kluyveromyces marxianus NCYC 587 e Hansenula mrakii NCYC 500. A β-1,3 glucanase purificada foi capaz de lisar as leveduras Saccharomyces cerevisiae KL-88, Saccharomyces capensis, Debaromyces vanriji, Pachysolen tannophillus, Kluyveromyces drosophilarum, Candida glabrata, Hansenula mrakii e Pichia membranaefaciens e formar protoplastos de Saccharomyces cerevisiae KL-88.The aim of this work was the application of lytic β-1,3 glucanase obtained from Cellulosimicrobium cellulans strain 191 in the production of protoplasts and lysis of yeast cell walls. The crude extract demonstrated lysis activity against the yeasts Kluyveromyces lodderi, Saccharomyces cerevisiae (Fleischmann and Itaiquara, S. cerevisiae KL-88, S. diastaticus NCYC 713, S. cerevisiae NCYC 1001, Candida glabrata NCYC 388, Kluyveromyces marxianus NCYC 587, and Hansenula mrakii NCYC 500. The purified β-1,3 glucanase demonstrated lysis activity against the yeasts Saccharomyces cerevisiae KL-88, Saccharomyces capensis, Debaromyces vanriji, Pachysolen tannophillus, Kluyveromyces drosophilarum, Candida glabrata, Hansenula mrakii, and Pichia membranaefaciens, and it was able to produce Saccharomyces cerevisiae KL-88 protoplasts.

  20. [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 phospholipase were positive in eight of nine isolates. As a result, the reason of increase in the incidence of this Candida species, which does not show significant resistance and presents mostly phospholipase activity as a virulence factor, should be investigated in more detail.

  1. Kinetics and Thermal Properties of Crude and Purified β-Galactosidase with Potential for the Production of Galactooligosaccharides

    Directory of Open Access Journals (Sweden)

    Anna Rafaela Cavalcante Braga

    2013-01-01

    Full Text Available β-Galactosidase is an enzyme that catalyzes the hydrolysis of lactose. It has potential importance due to various applications in the food and dairy industries, involving lactose-reduced ingredients. The properties of two β-galactosidase enzymes, crude and purified, from different sources, Kluyveromyces marxianus CCT 7082 and Kluyveromyces marxianus ATCC 16045, were analyzed. The pH and temperature optima, deactivation energy, thermal stability and kinetic and thermodynamic parameters were determined, as well as the ability to hydrolyze lactose and produce galactooligosaccharides. Purification process improved the properties of the enzymes, and the results showed that purified enzymes from both strains had a higher optimum temperature, and lower values of Km, thus showing greater affinity for o-nitrophenyl-β-D-galactopiranoside than the crude enzymes. The production of galactooligosaccharides was also greater when using purified enzymes, increasing the synthesis by more than 30 % by both strains.

  2. Effect of multiple substrates in ethanol fermentations from cheese whey

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C J; Jayanata, Y; Bajpai, R K

    1987-01-01

    Ethanol fermentations from cheese whey by Kluyveromyces marxianus CBS 397 were investigated. Cheese whey, which contains lactose as the major sugar, has been found to have small amounts of glucose and galactose, depending on the source and operating conditions. Fermentation performance was strongly influenced by the presence of glucose and galactose. However, lactose did not significantly affect the cell growth and product formation even at a high concentration. A logistical model was proposed to take into account the effect of lactose. (Refs. 6).

  3. Phytase-producing capacity of yeasts isolated from traditional African fermented food products and PHYPk gene expression of Pichia kudriavzevii strains

    DEFF Research Database (Denmark)

    Greppi, Anna; Krych, Lukasz; Costantini, Antonella

    2015-01-01

    Phytate is known as a strong chelate of minerals causing their reduced uptake by the human intestine. Ninety-three yeast isolates from traditional African fermented food products, belonging to nine species (Pichia kudriavzevii, Saccharomyces cerevisiae, Clavispora lusitaniae, Kluyveromyces...... marxianus, Millerozyma farinosa, Candida glabrata, Wickerhamomyces anomalus, Hanseniaspora guilliermondii and Debaryomyces nepalensis) were screened for phytase production on solid and liquid media. 95% were able to grow in the presence of phytate as sole phosphate source, P. kudriavzevii being the best...

  4. A new search for thermotolerant yeasts, its characterization and optimization using response surface methodology for ethanol production.

    Science.gov (United States)

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

    2015-01-01

    The progressive rise in energy crisis followed by green house gas (GHG) emissions is serving as the driving force for bioethanol production from renewable resources. Current bioethanol research focuses on lignocellulosic feedstocks as these are abundantly available, renewable, sustainable and exhibit no competition between the crops for food and fuel. However, the technologies in use have some drawbacks including incapability of pentose fermentation, reduced tolerance to products formed, costly processes, etc. Therefore, the present study was carried out with the objective of isolating hexose and pentose fermenting thermophilic/thermotolerant ethanologens with acceptable product yield. Two thermotolerant isolates, NIRE-K1 and NIRE-K3 were screened for fermenting both glucose and xylose and identified as Kluyveromyces marxianus NIRE-K1 and K. marxianus NIRE-K3. After optimization using Face-centered Central Composite Design (FCCD), the growth parameters like temperature and pH were found to be 45.17°C and 5.49, respectively for K. marxianus NIRE-K1 and 45.41°C and 5.24, respectively for K. marxianus NIRE-K3. Further, batch fermentations were carried out under optimized conditions, where K. marxianus NIRE-K3 was found to be superior over K. marxianus NIRE-K1. Ethanol yield (Y x∕s ), sugar to ethanol conversion rate (%), microbial biomass concentration (X) and volumetric product productivity (Q p ) obtained by K. marxianus NIRE-K3 were found to be 9.3, 9.55, 14.63, and 31.94% higher than that of K. marxianus NIRE-K1, respectively. This study revealed the promising potential of both the screened thermotolerant isolates for bioethanol production.

  5. A new search for thermotolerant yeasts, its characterization and optimization using response surface methodology for ethanol production

    Directory of Open Access Journals (Sweden)

    Richa eArora

    2015-09-01

    Full Text Available The progressive rise in energy crisis followed by green house gas (GHG emissions is serving as the driving force for bioethanol production from renewable resources. Current bioethanol research focuses on lignocellulosic feedstocks as these are abundantly available, renewable, sustainable and exhibit no competition between the crops for food and fuel. However, the technologies in use have some drawbacks including incapability of pentose fermentation, reduced tolerance to products formed, costly processes, etc. Therefore, the present study was carried out with the objective of isolating hexose and pentose fermenting thermophilic/ thermotolerant ethanologens with acceptable product yield. Two thermotolerant isolates, NIRE-K1 and NIRE-K3 were screened for fermenting both glucose and xylose and identified as Kluyveromyces marxianus NIRE-K1 and K. marxianus NIRE-K3. After optimization using FCCD (Face-centered Central Composite Design, the growth parameters like temperature and pH were found to be 45.17 oC and 5.49, respectively for K. marxianus NIRE-K1 and 45.41 oC and 5.24, respectively for K. marxianus NIRE-K3. Further, batch fermentations were carried out under optimized conditions, where K. marxianus NIRE-K3 was found to be superior over K. marxianus NIRE-K1. Ethanol yield (Yx/s, sugar to ethanol conversion rate (%, microbial biomass concentration (X and volumetric product productivity (Qp obtained by K. marxianus NIRE-K3 were found to be 9.3%, 9.55%, 14.63% and 31.94% higher than that of K. marxianus NIRE-K1, respectively. This study revealed the promising potential of both the screened thermotolerant isolates for bioethanol production.

  6. EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2015. Scientific Opinion on the substantiation of a health claim related to β-galactosidase from Kluyveromyces lactis in Colief® and a reduction of gastrointestinal discomfort pursuant to Article 14 of Regulation (EC

    DEFF Research Database (Denmark)

    Tetens, Inge

    2015-01-01

    provided in the publication and that supplied later by the applicant was inadequate to allow a scientific evaluation. The second study with methodological limitations showed an effect of the food on crying time in infants fed exclusively with milk. This study also provided some evidence for the proposed...... an opinion on the scientific substantiation of a health claim related to β-galactosidase from Kluyveromyces lactis in Colief® and a reduction of gastrointestinal discomfort. The Panel considers that the food is sufficiently characterised in relation to the claimed effect. A reduction of gastrointestinal...... discomfort is a beneficial physiological effect for infants and young children. The applicant provided two human intervention studies for the substantiation of the health claim. No conclusions could be drawn from one of the two studies for the scientific substantiation of the claim, as the information...

  7. Dynamics of yeast immobilized-cell fluidized-bed bioreactors systems in ethanol fermentation from lactose-hydrolyzed whey and whey permeate.

    Science.gov (United States)

    Gabardo, Sabrina; Pereira, Gabriela Feix; Klein, Manuela P; Rech, Rosane; Hertz, Plinho F; Ayub, Marco Antônio Záchia

    2016-01-01

    We studied the dynamics of ethanol production on lactose-hydrolyzed whey (LHW) and lactose-hydrolyzed whey permeate (LHWP) in batch fluidized-bed bioreactors using single and co-cultures of immobilized cells of industrial strains of Saccharomyces cerevisiae and non-industrial strains of Kluyveromyces marxianus. Although the co-culture of S. cerevisiae CAT-1 and K. marxianus CCT 4086 produced two- to fourfold the ethanol productivity of single cultures of S. cerevisiae, the single cultures of the K. marxianus CCT 4086 produced the best results in both media (Y EtOH/S = 0.47-0.49 g g(-1) and Q P = 1.39-1.68 g L(-1) h(-1), in LHW and LHWP, respectively). Ethanol production on concentrated LHWP (180 g L(-1)) reached 79.1 g L(-1), with yields of 0.46 g g(-1) for K. marxianus CCT 4086 cultures. Repeated batches of fluidized-bed bioreactor on concentrated LHWP led to increased ethanol productivity, reaching 2.8 g L(-1) h(-1).

  8. Kinetics of ethanol production from Jerusalem artichoke juice with some Klugveromyces species

    Energy Technology Data Exchange (ETDEWEB)

    Duvnjak, Z.; Kosaric, N.; Hayes, R.D.

    1981-01-01

    The kinetics of ethanol produce by Kluyveromyces marxianus ATCC 12708 and ATCC 10606, K. cicerisporus ATCC 22295, and K. fragilis 105 have been studied using raw juice of the Jerusalem artichoke in which the carbohydrates were not hydrolyzed prior to fermentation. The experiments revealed that this juice contains enough nutrients and can serve as a complete medium without additional nutrients both for growth of the yeasts and for ethanol production. It was found that both specific ethanol productivity and specific uptake rates were the highest with K. marxianus ATCC 12708 (1.68 g/g/hour and 3.78 g/g/hour respectively). This microorganism produced an ethanol yield of 87.5% of the theoretical value in 25 hours. (Refs. 15).

  9. Inulinase production in a packed bed reactor by solid state fermentation.

    Science.gov (United States)

    Dilipkumar, M; Rajamohan, N; Rajasimman, M

    2013-07-01

    In this work, production of inulinase was carried out in a packed bed reactor (PBR) under solid state fermentation. Kluyveromyces marxianus var. marxianus was used to produce the inulinase using pressmud as substrate. The parameters like air flow rate, packing density and particle size were optimized using response surface methodology (RSM) to maximize the inulinase production. The optimum conditions for the maximum inulinase production were: air flow rate - 0.82 L/min, packing density - 40 g/L and particle size - 0.0044 mm (mesh - 14/20). At these optimized conditions, the production of inulinase was found to be 300.5 unit/gram of dry substrate (U/gds). Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Non-Saccharomyces yeasts protect against epithelial cell barrier disruption induced by Salmonella enterica subsp. enterica serovar Typhimurium

    DEFF Research Database (Denmark)

    Smith, Ida Mosbech; Baker, A; Arneborg, Nils

    2015-01-01

    distinct patterns of non-Saccharomyces yeast modulation of epithelial cell barrier function. While the established probiotic yeast Saccharomyces boulardii increased TER across a Caco-2 monolayer by 30%, Kluyveromyces marxianus exhibited significantly stronger properties of TER enhancement (50% TER increase....... In addition, probiotic strains may be able to reduce epithelial barrier disruption caused by pathogenic species. The aim of this study was to explore non-Saccharomyces yeast modulation of epithelial cell barrier function in vitro. Benchmarking against established probiotic strains, we evaluated the ability......). In addition, our data demonstrate significant yeast-mediated modulation of Salmonella-induced epithelial cell barrier disruption and identify K. marxianus and Metschnikowia gruessii as two non-Saccharomyces yeasts capable of protecting human epithelial cells from pathogen invasion. SIGNIFICANCE AND IMPACT...

  11. Optimization studies for the bioconversion of Jerusalem artichoke tubers to ethanol and microbial biomass

    Energy Technology Data Exchange (ETDEWEB)

    Margaritis, A.; Bajpai, P.; Cannell, E.

    1981-01-01

    A total of 8 yeast and other microbial cultures were grown in the extract derived from the tubers of Jerusalem artichoke (Helianthus tuberosus) and screened according to the following optimization criteria: rates and yields of ethanol production, rates and yields of biomass production, and percent of original sugars utilized during fermentation. Batch growth kinetic parameters were also determined for the cultures studied. Kluyveromyces marxianus UCD (FST) 55-82 had the highest specific growth rate, 0.41/h, with a high ethanol yield, 88% of theoretical.

  12. Productivity and fermentability of Jerusalem artichoke according to harvesting date

    Energy Technology Data Exchange (ETDEWEB)

    Chabbert, N.; Arnoux, M.; Braun, Ph.; Galzy, P.; Guiraud, J.P.

    1983-01-01

    The amount of alcohol obtained per hectare of Jerusalem artichoke culture depends on the yield of tubers, the sugar content of the tubers and the fermentability of these sugars. Under Mediterranean climate conditions, the cultivar 'Violet commun' attained its maximum tuber production by 15 November, when the stems and leaves dried up, and then remained constant through the winter. The sugar content of the tubers varied little during this period. However, the sugar composition did vary with time: the polyfructosans were depolymerized. The fermentability of sugars without prior chemical hydrolysis was quite good with Kluyveromyces marxianus which showed high inulinase activity in contrast to Saccharomyces cerevisiae.

  13. Productivity and fermentability of Jerusalem artichoke according to harvesting date

    Energy Technology Data Exchange (ETDEWEB)

    Chabbert, N.; Braun, P.; Guiraud, J.P.; Arnoux, M.; Galzy, P.

    1983-01-01

    The amount of alcohol obtained per hectare of Jerusalem artichoke culture depends on the yield of tubers, the sugar content of the tubers and the fermentability of these sugars. Under Mediterranean climate conditions, the cultivar Violet commun attained its maximum tuber production by 15 November, when the stems and leaves dried up, and then remained constant through the winter. The sugar content of the tubers varied little during this period. However, the sugar composition did vary with time: the polyfructosans were depolymerized. The fermentability of sugars without prior chemical hydrolysis was quite good with Kluyveromyces marxianus which showed high inulinase activity in contrast to Saccaromyces cerevisiae. 5 figures, 1 table.

  14. Productivity and fermentability of Jerusalem artichoke according to harvesting date

    Energy Technology Data Exchange (ETDEWEB)

    Chabbert, M.; Braunt, Ph.; Guiraud, J.P.; Arnoux, M.; Galzy, P.

    1983-01-01

    The amount of alcohol obtained per hectare of Jerusalem artichoke culture depends on the yield of tubers, the sugar content of the tubers and the fermentability of these sugars. Under Mediterranean climate conditions, the cultivar 'Violet commun' attained its maximum tuber production by 15 November, when the stems and leaves dried up, and then remained constant through the winter. The sugar content of the tubers varied little during this period. However, the sugar composition did vary with time: the polyfructosans were depolymerized. The fermentability of sugars without prior chemical hydrolysis was quite good with Kluyveromyces marxianus which showed high inulinase activity in contrast to Saccharomyces cerevisiae. (Refs. 13).

  15. Lactic acid bacteria and yeasts associated with gowé production from sorghum in Bénin

    DEFF Research Database (Denmark)

    Vieira-Dalodé, G.; Jespersen, Lene; Hounhouigan, J.

    2007-01-01

    confusa, Lactobacillus mucosae, Pediococcus acidilactici, Pediococcus pentosaceus and Weissella kimchii. DNA from 200 strains of yeasts was amplified and the D1/D2 domain of the 26S rRNA gene was sequenced for selected isolates, revealing that the yeasts species were Kluyveromyces marxianus, Pichia...... at different fermentation times. DNA amplification by internal transcribed spacer-polymerase chain reaction of 288 lactic acid bacteria (LAB) isolates and 16S rRNA gene sequencing of selected strains revealed that the dominant LAB responsible for gowé fermentation were Lactobacillus fermentum, Weissella...

  16. Evaluation of the parameters effects on the bio-ethanol production process from Ricotta Cheese Whey

    DEFF Research Database (Denmark)

    Sansonetti, Sascha; Curcio, Stefano; Calabrò, Vincenza

    2010-01-01

    composite design, constituted by 26 runs, has been carried out, and the effects of the parameters have been evaluated. Eventually, once eliminated the negligible effects, Response Surface Methodology (RSM) has been applied to optimize the four parameters values in RCW fermentation process. After......The work consists of an experimental analysis to evaluate the effects of the variables temperature (T), pH, agitation rate (K) and initial lactose concentration (L) on the batch fermentation process of Ricotta Cheese Whey (RCW) into bio-ethanol by using the yeast Kluyveromyces marxianus. A central...

  17. Glycosylation in secreted proteins from yeast Kluyveromyces lactis

    Energy Technology Data Exchange (ETDEWEB)

    Santos, A.V.; Passos, F.M.L. [Universidade Federal de Vicosa (UFV), MG (Brazil). Dept. de Microbiologia. Lab. de Fisiologia de Microrganismos; Azevedo, B.R.; Pimenta, A.M.C.; Santoro, M.M. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Bioquimica e Imunologia. Lab. de Enzimologia e Fisico-Quimica de Proteina

    2008-07-01

    Full text: The nutritional status of a cell culture affects either the expression or the traffic of a number of proteins. The identification of the physiological conditions which favor protein secretion has important biotechnological consequences in designing systems for recombinant extracellular protein industrial production. Yeast Kluyvromyces lactis has been cultured in a continuous stirring tank bioreactor (CSTR) under nitrogen limitation at growth rates (0.03 h{sup -1} and 0.09 h{sup -1}) close to either exponential or stationary batch growth phases, respectively the objective was to investigate the extracellular glycoproteins at these two level of nitrogen limitation. Proteins from free cell extracts were separated by gradient SDS-PAGE (5-15%) and two-dimensional chromatography, and were analyzed by mass spectrometry (MALDI-TOF-TOF-MS). In SDS-PAGE analysis, differences in extracellular proteome were visualized: different proteins profiles at these two growth rates. The 0.09 h-1 growth rate showed larger number of bands using colloidal Coma ssie Blue staining. Different bands were detected at these two growth rates when the PAS assay for glycoprotein detection in polyacrylamide gel was used. The two-dimensional chromatogram profiles were comparatively distinguished between the 0.03 h{sup -1} and 0.09 h{sup -1} growth rate samples. Protein peaks from the second dimension, were subjected to mass spectrometry. The mass spectrums visualized showed glycosylated proteins with N-acetylglucosamine molecules and 8, 9 or 15 hexoses molecules. Comparisons between the proteins averaged mass values with the deduced proteins masses from K. lactis secreted proteins database indicated possible post-translational modifications, such as post-translational proteolysis, acetylation, deamidation and myristoylation.

  18. Glycosylation in secreted proteins from yeast Kluyveromyces lactis

    International Nuclear Information System (INIS)

    Santos, A.V.; Passos, F.M.L.; Azevedo, B.R.; Pimenta, A.M.C.; Santoro, M.M.

    2008-01-01

    Full text: The nutritional status of a cell culture affects either the expression or the traffic of a number of proteins. The identification of the physiological conditions which favor protein secretion has important biotechnological consequences in designing systems for recombinant extracellular protein industrial production. Yeast Kluyvromyces lactis has been cultured in a continuous stirring tank bioreactor (CSTR) under nitrogen limitation at growth rates (0.03 h -1 and 0.09 h -1 ) close to either exponential or stationary batch growth phases, respectively the objective was to investigate the extracellular glycoproteins at these two level of nitrogen limitation. Proteins from free cell extracts were separated by gradient SDS-PAGE (5-15%) and two-dimensional chromatography, and were analyzed by mass spectrometry (MALDI-TOF-TOF-MS). In SDS-PAGE analysis, differences in extracellular proteome were visualized: different proteins profiles at these two growth rates. The 0.09 h-1 growth rate showed larger number of bands using colloidal Coma ssie Blue staining. Different bands were detected at these two growth rates when the PAS assay for glycoprotein detection in polyacrylamide gel was used. The two-dimensional chromatogram profiles were comparatively distinguished between the 0.03 h -1 and 0.09 h -1 growth rate samples. Protein peaks from the second dimension, were subjected to mass spectrometry. The mass spectrums visualized showed glycosylated proteins with N-acetylglucosamine molecules and 8, 9 or 15 hexoses molecules. Comparisons between the proteins averaged mass values with the deduced proteins masses from K. lactis secreted proteins database indicated possible post-translational modifications, such as post-translational proteolysis, acetylation, deamidation and myristoylation

  19. Evaluation of Galactose Adapted Yeasts for Bioethanol Fermentation from Kappaphycus alvarezii Hydrolyzates.

    Science.gov (United States)

    Nguyen, Trung Hau; Ra, Chae Hun; Sunwoo, In Yung; Jeong, Gwi-Taek; Kim, Sung-Koo

    2016-07-28

    Bioethanol was produced from Kappaphycus alvarezii seaweed biomass using separate hydrolysis and fermentation (SHF). Pretreatment was evaluated for 60 min at 121°C using 12% (w/v) biomass slurry with 364 mM H2SO4. Enzymatic saccharification was then carried out at 45°C for 48 h using Celluclast 1.5 L. Ethanol fermentation with 12% (w/v) K. alvarezii hydrolyzate was performed using the yeasts Saccharomyces cerevisiae KCTC1126, Kluyveromyces marxianus KCTC7150, and Candida lusitaniae ATCC42720 with or without prior adaptation to high concentrations of galactose. When non-adapted S. cerevisiae, K. marxianus, and C. lusitaniae were used, 11.5 g/l, 6.7 g/l, and 6.0 g/l of ethanol were produced, respectively. When adapted S. cerevisiae, K. marxianus, and C. lusitaniae were used, 15.8 g/l, 11.6 g/l, and 13.4 g/l of ethanol were obtained, respectively. The highest ethanol concentration was 15.8 g/l, with YEtOH = 0.43 and YT% = 84.3%, which was obtained using adapted S. cerevisiae.

  20. Non-Saccharomyces yeasts protect against epithelial cell barrier disruption induced by Salmonella enterica subsp. enterica serovar Typhimurium.

    Science.gov (United States)

    Smith, I M; Baker, A; Arneborg, N; Jespersen, L

    2015-11-01

    The human gastrointestinal epithelium makes up the largest barrier separating the body from the external environment. Whereas invasive pathogens cause epithelial barrier disruption, probiotic micro-organisms modulate tight junction regulation and improve epithelial barrier function. In addition, probiotic strains may be able to reduce epithelial barrier disruption caused by pathogenic species. The aim of this study was to explore non-Saccharomyces yeast modulation of epithelial cell barrier function in vitro. Benchmarking against established probiotic strains, we evaluated the ability of four nonpathogenic yeast species to modulate transepithelial electrical resistance (TER) across a monolayer of differentiated human colonocytes (Caco-2 cells). Further, we assessed yeast modulation of a Salmonella Typhimurium-induced epithelial cell barrier function insult. Our findings demonstrate distinct patterns of non-Saccharomyces yeast modulation of epithelial cell barrier function. While the established probiotic yeast Saccharomyces boulardii increased TER across a Caco-2 monolayer by 30%, Kluyveromyces marxianus exhibited significantly stronger properties of TER enhancement (50% TER increase). In addition, our data demonstrate significant yeast-mediated modulation of Salmonella-induced epithelial cell barrier disruption and identify K. marxianus and Metschnikowia gruessii as two non-Saccharomyces yeasts capable of protecting human epithelial cells from pathogen invasion. This study demonstrates distinct patterns of non-Saccharomyces yeast modulation of epithelial cell barrier function in vitro. Further, our data demonstrate significant yeast-mediated modulation of Salmonella Typhimurium-induced epithelial cell barrier disruption and identify Kluyveromyces marxianus and Metschnikowia gruessii as two non-Saccharomyces yeasts capable of protecting human epithelial cells from pathogen invasion. This study is the first to demonstrate significant non-Saccharomyces yeast

  1. VARIAÇÕES NA MICROBIOTA LEVEDURIFORME DO FERMENTO ENDÓGENO UTILIZADO NA PRODUÇÃO DO QUEIJO CANASTRA

    Directory of Open Access Journals (Sweden)

    Juliana E. Nóbrega

    2008-10-01

    Full Text Available Variações na microbiota leveduriforme presente no fermento endógeno utilizado para fabricação do queijo Canastra foram avaliadas no período das águas (PA e no período da seca (PS. O queijo Canastra é produzido na região da Serra da Canastra, Minas Gerais, de forma artesanal a partir de leite cru de vaca e utiliza como cultura iniciadora um fermento endógeno obtido após prensagem e salga do queijo. Um total de 115 estirpes foram isoladas de 16 amostras do fermento endógeno coletadas em 8 unidades produtoras nos dois períodos amostrados e identificadas pela metodologia tradicional e pelo sistema API C 20 AUX. As espécies de leveduras predominantes no PA foram Debaryomyces hansenii, Torulaspora delbruekii e Kluyveromyces lactis. No PS, predominaram as espécies Kluyveromyces lactis, Torulaspora delbruekii e Kluyveromyces marxianus. Os resultados demonstram que as espécies leveduriformes presentes no fermento endógeno da Serra da Canastra, nos dois períodos avaliados, são basicamente as mesmas, variando a freqüência com as quais ocorrem.

  2. EVALUATION OF INHIBITORY MEASURES FOR FOOD SPOILER YEAST CANDIDA KRUSEI DURING FERMENTATION PROCESS BY CHEMICAL, BIOCHEMICAL AND NANOPARTICLE APPROACHES

    Directory of Open Access Journals (Sweden)

    Indrani Bhattacharya

    2016-06-01

    Full Text Available Screening of chemical, biochemical and biomolecule-nanoparticle methods for the inhibition of Candida krusei were evaluated without hampering the growth of dairy yeast Kluyveromyces marxianus. The effective inhibition was observed with the help of H2O2, Williopsis saturnus, at specific combination of pH and temperature (pH 5.0 and 40 °C and Ag-KT4561 nanoparticles among the various methods used. However, the most efficient inhibition was observed with Ag-KT4561 nanoparticles. In general H2O2 works best at pH range 4.0 to 10.0 and at temperature 30 °C or above. H2O2 concentration of 4000 ppm at 45 °C and pH 5.5 exhibited significant inhibition of C. krusei, while K. marxianus remains unaffected. But, when used with lyophilized supernatant of W. saturnus, 2400 ppm H2O2 was effective. Further, nanoparticle with silver was synthesized to reduce the quantity of killer protein and enhance the efficiency of protein. Complete inhibition of C. krusei was observed at 350 µM of synthesized silver nano-particle (AgNPs of the killer protein from W. saturnus, with little effect on K. marxianus concentration. A stability test confirms the effect of protein silver nanoparticles on C. krusei for more than 20 weeks without any change in pH and temperature. Thus, the nanoparticles could be potentially used for inhibition of C. krusei without affecting the growth of K. marxianus and the process could be run non-aseptically.

  3. Feasibility of biohydrogen production from industrial wastes using defined microbial co-culture

    Directory of Open Access Journals (Sweden)

    Peng Chen

    2015-01-01

    Full Text Available BACKGROUND: The development of clean or novel alternative energy has become a global trend that will shape the future of energy. In the present study, 3 microbial strains with different oxygen requirements, including Clostridium acetobutylicum ATCC 824, Enterobacter cloacae ATCC 13047 and Kluyveromyces marxianus 15D, were used to construct a hydrogen production system that was composed of a mixed aerobic-facultative anaerobic-anaerobic consortium. The effects of metal ions, organic acids and carbohydrate substrates on this system were analyzed and compared using electrochemical and kinetic assays. It was then tested using small-scale experiments to evaluate its ability to convert starch in 5 L of organic wastewater into hydrogen. For the one-step biohydrogen production experiment, H1 medium (nutrient broth and potato dextrose broth was mixed directly with GAM broth to generate H2 medium (H1 medium and GAM broth. Finally, Clostridium acetobutylicum ATCC 824, Enterobacter cloacae ATCC 13047 and Kluyveromyces marxianus 15D of three species microbial co-culture to produce hydrogen under anaerobic conditions. For the two-step biohydrogen production experiment, the H1 medium, after cultured the microbial strains Enterobacter cloacae ATCC 13047 and Kluyveromyces marxianus 15D, was centrifuged to remove the microbial cells and then mixed with GAM broth (H2 medium. Afterward, the bacterial strain Clostridium acetobutylicum ATCC 824 was inoculated into the H2 medium to produce hydrogen by anaerobic fermentation. RESULTS: The experimental results demonstrated that the optimum conditions for the small-scale fermentative hydrogen production system were at pH 7.0, 35°C, a mixed medium, including H1 medium and H2 medium with 0.50 mol/L ferrous chloride, 0.50 mol/L magnesium sulfate, 0.50 mol/L potassium chloride, 1% w/v citric acid, 5% w/v fructose and 5% w/v glucose. The overall hydrogen production efficiency in the shake flask fermentation group was 33.7 m

  4. Production of fermented cheese whey-based beverage using kefir grains as starter culture: evaluation of morphological and microbial variations.

    Science.gov (United States)

    Magalhães, Karina Teixeira; Pereira, Maria Alcina; Nicolau, Ana; Dragone, Giuliano; Domingues, Lucília; Teixeira, José António; de Almeida Silva, João Batista; Schwan, Rosane Freitas

    2010-11-01

    Whey valorization concerns have led to recent interest on the production of whey beverage simulating kefir. In this study, the structure and microbiota of Brazilian kefir grains and beverages obtained from milk and whole/deproteinised whey was characterized using microscopy and molecular techniques. The aim was to evaluate its stability and possible shift of probiotic bacteria to the beverages. Fluorescence staining in combination with Confocal Laser Scanning Microscopy showed distribution of yeasts in macro-clusters among the grain's matrix essentially composed of polysaccharides (kefiran) and bacteria. Denaturing gradient gel electrophoresis displayed communities included yeast affiliated to Kluyveromyces marxianus, Saccharomyces cerevisiae, Kazachatania unispora, bacteria affiliated to Lactobacillus kefiranofaciens subsp. Kefirgranum, Lactobacillus kefiranofaciens subsp. Kefiranofaciens and an uncultured bacterium also related to the genus Lactobacillus. A steady structure and dominant microbiota, including probiotic bacteria, was detected in the analyzed kefir beverages and grains. This robustness is determinant for future implementation of whey-based kefir beverages.

  5. High-temperature fermentation. How can processes for ethanol production at high temperatures become superior to the traditional process using mesophilic yeast?

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Banat, Babiker M.A.; Hoshida, Hisashi; Nonklang, Sanom; Akada, Rinji [Yamaguchi Univ. Graduate School of Medicine, Ube (Japan). Dept. of Applied Molecular Bioscience; Ano, Akihiko [Iwata Chemical Co. Ltd. (Japan)

    2010-01-15

    The process of ethanol fermentation has a long history in the production of alcoholic drinks, but much larger scale production of ethanol is now required to enable its use as a substituent of gasoline fuels at 3%, 10%, or 85% (referred to as E3, E10, and E85, respectively). Compared with fossil fuels, the production costs are a major issue for the production of fuel ethanol. There are a number of possible approaches to delivering cost-effective fuel ethanol production from different biomass sources, but we focus in our current report on high-temperature fermentation using a newly isolated thermotolerant strain of the yeast Kluyveromyces marxianus. We demonstrate that a 5 C increase only in the fermentation temperature can greatly affect the fuel ethanol production costs. We contend that this approach may also be applicable to the other microbial fermentations systems and propose that thermotolerant mesophilic microorganisms have considerable potential for the development of future fermentation technologies. (orig.)

  6. Impact of starter cultures and fermentation techniques on the volatile aroma and sensory profile of chocolate

    DEFF Research Database (Denmark)

    Crafack, Michael; Keul, Hanna; Eskildsen, Carl Emil Aae

    2014-01-01

    cultures on the formation of flavour precursors, composition of volatile aroma compounds and sensory profile was investigated in cocoa inoculated with cultures encompassing a highly aromatic strain of Pichia kluyveri or a pectinolytic strain of Kluyveromyces marxianus, and compared to commercially...... fermented heap and tray cocoa. Although only minor differences in the concentration of free amino acids and reducing sugars was measured, identification and quantification by dynamic headspace gas chromatography-mass spectrometry (HS/GC-MS) revealed pronounced differences in the composition of volatiles...... in roasted cocoa liquors and finished chocolates. 19 of the 56 volatile compounds identified in the chocolates were found in significantly higher amounts in the tray fermented sample, whilst significantly higher amounts of 2-methoxyphenol was measured in the two inoculated chocolates. The P. kluyveri...

  7. Solid phase fermentation of Helianthus tuberosus for ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Baerwald, G.; Hamad, S.H.

    1989-01-01

    The direct fermentation of pure inulin and hammer mill crushed Helianthus tuberosus tubers (topinambur, Jerusalem artichoke) was studied using two heat-tolerant yeasts, namely Kluyveromyces marxianus and Candida kefyr. A Saccharomyces cerevisiae was included in the study so as to compare the yields of these two yeasts with that of a commercial distiller's yeast. The inulin fermentation was carried out in an 18-L bioreactor using the fed-batch and the batch-fermentation methods. The final ethanol concentration was 6.1% (L/L) which represents 82% of the theoretical yield. Commercial scale experiments with hammer mill crushed tubers gave yields lower than those found in the laboratory: 69% of the theoretical yield for direct fermentation without enzyme addition, and about 91% when cellolytic enzymes were added.

  8. Yeast dynamics during spontaneous fermentation of mawe and tchoukoutou, two traditional products from Benin

    DEFF Research Database (Denmark)

    Greppi, Anna; Rantisou, Kalliopi; Padonou, Wilfrid

    2013-01-01

    Mawe and tchoukoutou are two traditional fermented foods largely consumed in Benin, West Africa. Their preparations remain as a house art and they are the result of spontaneous fermentation processes. In this study, dynamics of the yeast populations occurring during spontaneous fermentations...... of mawe and tchoukoutou were investigated using both culture-dependent and -independent approaches. For each product, two productions were followed. Samples were taken at different fermentation times and yeasts were isolated, resulting in the collection of 177 isolates. They were identified by the PCR......-DGGE technique followed by the sequencing of the D1/D2 domain of the 26S rRNA gene. The predominant yeast species identified were typed by rep-PCR. Candida krusei was the predominant yeast species in mawe fermentation followed by Candida glabrata and Kluyveromyces marxianus. Other yeast species were detected...

  9. Screening of native yeast from Agave duranguensis fermentation for isoamyl acetate production

    Directory of Open Access Journals (Sweden)

    Gerardo Hernández-Carbajal

    2013-06-01

    Full Text Available In this work, fifty yeast strains, isolated from the spontaneous alcoholic fermentation of Agave duranguensis to produce mezcal, were tested using the double coupling system. These yeasts were from the genera Pichia, Torulaspora, Saccharomyces, Kluyveromyces, Deckera, Hanseniaspora, and Candida. P. fermentans ITD00165 was the best isoamyl acetate producer, yielding 0.38 g/L of ester after incubation for 24 h, while K. marxianus ITD00211 produced 0.32 g/L of ester. Thus P. fermentans TD00165 could be considered as an excellent choice for use in optimization studies of the culture medium and bioreactor operating conditions to develop a process for biotechnological production of isoamyl acetate.

  10. Effect of the yeast and bacteria biomass on the microbiota in the rumen.

    Science.gov (United States)

    Vamanu, E; Vamanu, A; Popa, O; Vassu, Tatiana; Ghindea, Raluca; Pelinescu, Diana; Nita, Sultana; Babeanu, Narcisa

    2008-09-15

    This study aims at obtaining a probiotic product based on viable biomass from 6 yeast strains and 2 strains of lactic bacteria used for nutrition of animals. The strains are subjected to some resistance tests, at temperature, pH, pepsin, pancreatin and biliary salts so as to make obvious their viability. Tests were done by comparison to the witness strain and respectively a protective solution based on mucin and casein. Based on the resulted viabilities 2 products are formulated. Their effect is tested by inoculating fresh rumen content and supervising the microbic balance for a period of 12 days. After the final tests, it resulted that the product Fpl (20% Saccharomyces cerevisiae 1-29, 10% Kluyveromyces marxianus R-CS, 20% Issatchenkia orientalis R-BC, 30% Lactobacillus paracasei CMGB16, 20% Enterococcus faecium GM8) was chosen because anaerobic strains were preponderant as a consequence of the tests performed with rumen.

  11. Fructanase and fructosyltransferase activity of non-Saccharomyces yeasts isolated from fermenting musts of Mezcal.

    Science.gov (United States)

    Arrizon, Javier; Morel, Sandrine; Gschaedler, Anne; Monsan, Pierre

    2012-04-01

    Fructanase and fructosyltransferase are interesting for the tequila process and prebiotics production (functional food industry). In this study, one hundred thirty non-Saccharomyces yeasts isolated from "Mezcal de Oaxaca" were screened for fructanase and fructosyltransferase activity. On solid medium, fifty isolates grew on Agave tequilana fructans (ATF), inulin or levan. In liquid media, inulin and ATF induced fructanase activities of between 0.02 and 0.27U/ml depending of yeast isolate. High fructanase activity on sucrose was observed for Kluyveromyces marxianus and Torulaspora delbrueckii, while the highest fructanase activity on inulin and ATF was observed for Issatchenkia orientalis, Cryptococcus albidus, and Candida apicola. Zygosaccharomyces bisporus and Candida boidinii had a high hydrolytic activity on levan. Sixteen yeasts belonging to K. marxianus, T. delbrueckii and C. apicola species were positive for fructosyltransferase activity. Mezcal microbiota proved to showed to be a source for new fructanase and fructosyltransferases with potential application in the tequila and food industry. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Isolation, identification and characterization of yeasts from fermented goat milk of the Yaghnob Valley in Tajikistan

    Directory of Open Access Journals (Sweden)

    Linnea Annie Qvirist

    2016-11-01

    Full Text Available The geographically isolated region of the Yaghnob Valley, Tajikistan, has allowed its inhabitants to maintain a unique culture and lifestyle. Their fermented goat milk constitutes one of the staple foods for the Yaghnob population, and is produced by backslopping, i.e. using the previous fermentation batch to inoculate the new one. This study addresses the yeast composition of the fermented milk, assessing genotypic and phenotypic properties.The 52 isolates included in this study revealed small species diversity, belonging to Kluyveromyces marxianus, Pichia fermentans, Saccharomyces cerevisiae and one Kazachstania unispora. The K. marxianus strains showed two different genotypes, one of which never described previously. The two genetically different groups also differed significantly in several phenotypic characteristics, such as tolerance towards high temperatures, low pH, and presence of acid. Microsatellite analysis of the S. cerevisiae strains from this study, compared to 350 previously described strains, attributed the Yaghnobi S. cerevisiae to two different ancestry origins, both distinct from the wine and beer strains, and similar to strains isolated from human and insects faeces, suggesting a peculiar origin of these strains, and the existence of a gut reservoir for S. cerevisiae.Our work constitutes a foundation for strain selection for future applications as starter cultures in food fermentations. This work is the first ever on yeast diversity from fermented milk of the previously unexplored area of the Yaghnob Valley.

  13. Characterization and stability of lactobacilli and yeast microbiota in kefir grains.

    Science.gov (United States)

    Vardjan, T; Mohar Lorbeg, P; Rogelj, I; Čanžek Majhenič, A

    2013-05-01

    Characterization and stability of lactobacilli and yeasts from kefir grains using culture-dependent and culture-independent methods were investigated in this study. Culture-dependent analysis, followed by sequencing of 16S ribosomal DNA for bacteria and 26S rRNA gene for yeasts, revealed 3 different species of lactobacilli and yeasts, respectively. The most frequently isolated bacterial species were Lactobacillus kefiranofaciens ssp. kefirgranum, Lb. parakefiri, and Lb. kefiri, whereas yeasts belonged to Kluyveromyces marxianus, Kazachstania exigua, and Rhodosporidium kratochvilovae. This study is the first to report on the presence of R. kratochvilovae in kefir grains. On the other hand, PCR-denaturing gradient gel electrophoresis in the culture-independent method showed that the dominant microorganisms were Lb. kefiranofaciens ssp. kefirgranum, Kl. marxianus and Ka. exigua, but did not reveal bands corresponding to Lb. parakefiri, Lb. kefiri, or R. kratochvilovae. Our results support the necessity of combining more techniques for detailed and reliable study of microbial communities in kefir grains. Another interesting finding confirmed that the detected dominant microbiota of kefir grains is very stable and did not change over experimental time. This finding is important to ensure consistent product quality. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  14. Microbiological and chemical properties of kefir manufactured by entrapped microorganisms isolated from kefir grains.

    Science.gov (United States)

    Chen, T-H; Wang, S-Y; Chen, K-N; Liu, J-R; Chen, M-J

    2009-07-01

    In this study, various yeasts (Kluyveromyces marxianus, Saccharomyces turicensis, Pichia fermentans) and lactic acid bacteria (Lactobacillus kefiranofaciens, Lactobacillus kefiri, Leuconostoc mesenteroides) were entrapped in 2 different microspheres using an entrapment ratio for the strains that was based on the distribution ratio of these organisms in kefir grains. The purpose of this study was to develop a new technique to produce kefir using immobilized starter cultures isolated from kefir grains. An increase in cell counts with fermentation cycles was observed for both the lactic acid bacteria (LAB) and yeasts, whereas the cell counts of kefir grains were very stable during cultivation. Scanning electron microscopy showed that the short-chain lactobacilli and lactococci occupied the surface of the LAB microspheres, whereas the long-chain lactobacilli were inside the microspheres. When the yeasts were analyzed, cells at a high density were entrapped in cracks on the surface and within the microspheres, where they were surrounded by the short-chain lactobacilli. The distribution of the LAB and yeast species in kefir produced from grains and microspheres showed that there was no significant difference between the kefirs produced by the 2 methods; moreover, Leu. mesenteroides and K. marxianus were the predominating microflora in both types of kefir. There was no significant difference in the ethanol and exopolysaccharide contents between the 2 kefirs, although the acidity was different.

  15. Identification of yeast and bacteria involved in the mezcal fermentation of Agave salmiana.

    Science.gov (United States)

    Escalante-Minakata, P; Blaschek, H P; Barba de la Rosa, A P; Santos, L; De León-Rodríguez, A

    2008-06-01

    To identify the yeast and bacteria present in the mezcal fermentation from Agave salmiana. The restriction and sequence analysis of the amplified region, between 18S and 28S rDNA and 16S rDNA genes, were used for the identification of yeast and bacteria, respectively. Eleven different micro-organisms were identified in the mezcal fermentation. Three of them were the following yeast: Clavispora lusitaniae, Pichia fermentans and Kluyveromyces marxianus. The bacteria found were Zymomonas mobilis subsp. mobilis and Zymomonas mobilis subsp. pomaceae, Weissella cibaria, Weissella paramesenteroides, Lactobacillus pontis, Lactobacillus kefiri, Lactobacillus plantarum and Lactobacillus farraginis. The phylogenetic analysis of 16S rDNA and ITS sequences showed that microbial diversity present in mezcal is dominated by bacteria, mainly lactic acid bacteria species and Zymomonas mobilis. Pichia fermentans and K. marxianus could be micro-organisms with high potential for the production of some volatile compounds in mezcal. We identified the community of bacteria and yeast present in mezcal fermentation from Agave salmiana.

  16. Valorization of Pectin-rich Agroindustrial Wastes by Fermentation

    Directory of Open Access Journals (Sweden)

    Manuel Serrat-Díaz

    2015-12-01

    Full Text Available The search of the biotechnological ways to the integral use of the wastes generated by the coffee and citric agroindustries, is a current problem. The biotransformation of coffee pulp and orange mesocarp during aerobic and anoxic fermentation with the pectinolític yeast Kluyveromyces marxianus CCEBI 2011 was studied in this research. It was found that coffee pulp is a better substrate to yeast growth, which was evidenced throughout a better conversion of the carbon and energy source. The yeast used in 24 h the reducing and neutral sugars from substrates efficiently, either under aerobic or oxygen-limited cultures. The excretion of the polygalacturonase enzyme by the yeast lead to the increasing in the pectic substances extraction, which reached the 225 % and 33 % for coffee pulp and orange mesocarp, respectively, compared with the amounts which were extracted during substrates sterilization. The enzyme production by the microorganism presented not significantly differences in relation to the substrate used, but the contrary occurred with respect to glucose concentration in the medium. These results point to the promissory use of the K. marxianus CCEBI 2011 yeast strain in the valorization of pectin-rich agricultural wastes by means of their conversion in potential plant elicitors and prebiotics oligogalacturonides-based.

  17. Evaluation of hardboard manufacturing process wastewater as a feedstream for ethanol production.

    Science.gov (United States)

    Groves, Stephanie; Liu, Jifei; Shonnard, David; Bagley, Susan

    2013-07-01

    Waste streams from the wood processing industry can serve as feedstream for ethanol production from biomass residues. Hardboard manufacturing process wastewater (HPW) was evaluated on the basis of monomeric sugar recovery and fermentability as a novel feedstream for ethanol production. Dilute acid hydrolysis, coupled with concentration of the wastewater resulted in a hydrolysate with 66 g/l total fermentable sugars. As xylose accounted for 53 % of the total sugars, native xylose-fermenting yeasts were evaluated for their ability to produce ethanol from the hydrolysate. The strains selected were, in decreasing order by ethanol yields from xylose (Y p/s, based on consumed sugars), Scheffersomyces stipitis ATCC 58785 (CBS 6054), Pachysolen tannophilus ATCC 60393, and Kluyveromyces marxianus ATCC 46537. The yeasts were compared on the basis of substrate utilization and ethanol yield during fermentations of the hydrolysate, measured using an HPLC. S. stipitis, P. tannophilus, and K. marxianus produced 0.34, 0.31, and 0.36 g/g, respectively. The yeasts were able to utilize between 58 and 75 % of the available substrate. S. stipitis outperformed the other yeast during the fermentation of the hydrolysate; consuming the highest concentration of available substrate and producing the highest ethanol concentration in 72 h. Due to its high sugar content and low inhibitor levels after hydrolysis, it was concluded that HPW is a suitable feedstream for ethanol production by S. stipitis.

  18. Lactic acid bacteria and yeasts associated with gowé production from sorghum in Bénin.

    Science.gov (United States)

    Vieira-Dalodé, G; Jespersen, L; Hounhouigan, J; Moller, P L; Nago, C M; Jakobsen, M

    2007-08-01

    To identify the dominant micro-organisms involved in the production of gowé, a fermented beverage, and to select the most appropriate species for starter culture development. Samples of sorghum gowé produced twice at three different production sites were taken at different fermentation times. DNA amplification by internal transcribed spacer-polymerase chain reaction of 288 lactic acid bacteria (LAB) isolates and 16S rRNA gene sequencing of selected strains revealed that the dominant LAB responsible for gowé fermentation were Lactobacillus fermentum, Weissella confusa, Lactobacillus mucosae, Pediococcus acidilactici, Pediococcus pentosaceus and Weissella kimchii. DNA from 200 strains of yeasts was amplified and the D1/D2 domain of the 26S rRNA gene was sequenced for selected isolates, revealing that the yeasts species were Kluyveromyces marxianus, Pichia anomala, Candida krusei and Candida tropicalis. Gowé processing is characterized by a mixed fermentation dominated by Lact. fermentum, W. confusa and Ped. acidilactici for the LAB and by K. marxianus, P. anomala and C. krusei for the yeasts. The diversity of the LAB and yeasts identified offers new opportunities for technology upgrading and products development in gowé production. The identified species can be used as possible starter for a controlled fermentation of gowé.

  19. Yeast communities associated with artisanal mezcal fermentations from Agave salmiana.

    Science.gov (United States)

    Verdugo Valdez, A; Segura Garcia, L; Kirchmayr, M; Ramírez Rodríguez, P; González Esquinca, A; Coria, R; Gschaedler Mathis, A

    2011-11-01

    The aims of this work were to characterize the fermentation process of mezcal from San Luis Potosi, México and identify the yeasts present in the fermentation using molecular culture-dependent methods (RFLP of the 5.8S-ITS and sequencing of the D1/D2 domain) and also by using a culture-independent method (DGGE). The alcoholic fermentations of two separate musts obtained from Agave salmiana were analyzed. Sugar, ethanol and major volatile compounds concentrations were higher in the first fermentation, which shows the importance of having a quality standard for raw materials, particularly in the concentration of fructans, in order to produce fermented Agave salmiana must with similar characteristics. One hundred ninety-two (192) different yeast colonies were identified, from those present on WL agar plates, by RFLP analysis of the ITS1-5.8S- ITS2 from the rRNA gene, with restriction endonucleases, HhaI, HaeIII and HinfI. The identified yeasts were: Saccharomyces cerevisiae, Kluyveromyces marxianus, Pichia kluyveri, Zygosaccharomyces bailii, Clavispora lusitaniae, Torulaspora delbrueckii, Candida ethanolica and Saccharomyces exiguus. These identifications were confirmed by sequencing the D1-D2 region of the 26S rRNA gene. With the PCR-DGGE method, bands corresponding to S. cerevisiae, K. marxianus and T. delbrueckii were clearly detected, confirming the results obtained with classic techniques.

  20. Enhanced enzymatic hydrolysis and ethanol production from cashew apple bagasse pretreated with alkaline hydrogen peroxide.

    Science.gov (United States)

    da Costa, Jessyca Aline; Marques, José Edvan; Gonçalves, Luciana Rocha Barros; Rocha, Maria Valderez Ponte

    2015-03-01

    The effect of combinations and ratios between different enzymes has been investigated in order to assess the optimal conditions for hydrolysis of cashew apple bagasse pretreated with alkaline hydrogen peroxide (the solids named CAB-AHP). The separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes were evaluated in the ethanol production. The enzymatic hydrolysis conducted with cellulase complex and β-glucosidase in a ratio of 0.61:0.39, enzyme loading of 30FPU/g(CAB-AHP) and 66CBU/g(CAB-AHP), respectively, using 4% cellulose from CAB-AHP, turned out to be the most effective conditions, with glucose and xylose yields of 511.68 mg/g(CAB-AHP) and 237.8 mg/g(CAB-AHP), respectively. Fermentation of the pure hydrolysate by Kluyveromyces marxianus ATCC 36907 led to an ethanol yield of 61.8kg/ton(CAB), corresponding to 15 g/L ethanol and productivity of 3.75 g/( Lh). The ethanol production obtained for SSF process using K. marxianus ATCC 36907 was 18 g/L corresponding to 80% yield and 74.2kg/ton(CAB). Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Utilization of inulin-containing waste in industrial fermentations to produce biofuels and bio-based chemicals.

    Science.gov (United States)

    Hughes, Stephen R; Qureshi, Nasib; López-Núñez, Juan Carlos; Jones, Marjorie A; Jarodsky, Joshua M; Galindo-Leva, Luz Ángela; Lindquist, Mitchell R

    2017-04-01

    Inulins are polysaccharides that belong to an important class of carbohydrates known as fructans and are used by many plants as a means of storing energy. Inulins contain 20 to several thousand fructose units joined by β-2,1 glycosidic bonds, typically with a terminal glucose unit. Plants with high concentrations of inulin include: agave, asparagus, coffee, chicory, dahlia, dandelion, garlic, globe artichoke, Jerusalem artichoke, jicama, onion, wild yam, and yacón. To utilize inulin as its carbon and energy source directly, a microorganism requires an extracellular inulinase to hydrolyze the glycosidic bonds to release fermentable monosaccharides. Inulinase is produced by many microorganisms, including species of Aspergillus, Kluyveromyces, Penicillium, and Pseudomonas. We review various inulinase-producing microorganisms and inulin feedstocks with potential for industrial application as well as biotechnological efforts underway to develop sustainable practices for the disposal of residues from processing inulin-containing crops. A multi-stage biorefinery concept is proposed to convert cellulosic and inulin-containing waste produced at crop processing operations to valuable biofuels and bioproducts using Kluyveromyces marxianus, Yarrowia lipolytica, Rhodotorula glutinis, and Saccharomyces cerevisiae as well as thermochemical treatments.

  2. Altered Fermentation Performances, Growth, and Metabolic Footprints Reveal Competition for Nutrients between Yeast Species Inoculated in Synthetic Grape Juice-Like Medium

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    Stephanie Rollero

    2018-02-01

    Full Text Available The sequential inoculation of non-Saccharomyces yeasts and Saccharomyces cerevisiae in grape juice is becoming an increasingly popular practice to diversify wine styles and/or to obtain more complex wines with a peculiar microbial footprint. One of the main interactions is competition for nutrients, especially nitrogen sources, that directly impacts not only fermentation performance but also the production of aroma compounds. In order to better understand the interactions taking place between non-Saccharomyces yeasts and S. cerevisiae during alcoholic fermentation, sequential inoculations of three yeast species (Pichia burtonii, Kluyveromyces marxianus, Zygoascus meyerae with S. cerevisiae were performed individually in a synthetic medium. Different species-dependent interactions were evidenced. Indeed, the three sequential inoculations resulted in three different behaviors in terms of growth. P. burtonii and Z. meyerae declined after the inoculation of S. cerevisiae which promptly outcompeted the other two species. However, while the presence of P. burtonii did not impact the fermentation kinetics of S. cerevisiae, that of Z. meyerae rendered the overall kinetics very slow and with no clear exponential phase. K. marxianus and S. cerevisiae both declined and became undetectable before fermentation completion. The results also demonstrated that yeasts differed in their preference for nitrogen sources. Unlike Z. meyerae and P. burtonii, K. marxianus appeared to be a competitor for S. cerevisiae (as evidenced by the uptake of ammonium and amino acids, thereby explaining the resulting stuck fermentation. Nevertheless, the results suggested that competition for other nutrients (probably vitamins occurred during the sequential inoculation of Z. meyerae with S. cerevisiae. The metabolic footprint of the non-Saccharomyces yeasts determined after 48 h of fermentation remained until the end of fermentation and combined with that of S. cerevisiae. For

  3. Altered Fermentation Performances, Growth, and Metabolic Footprints Reveal Competition for Nutrients between Yeast Species Inoculated in Synthetic Grape Juice-Like Medium

    Science.gov (United States)

    Rollero, Stephanie; Bloem, Audrey; Ortiz-Julien, Anne; Camarasa, Carole; Divol, Benoit

    2018-01-01

    The sequential inoculation of non-Saccharomyces yeasts and Saccharomyces cerevisiae in grape juice is becoming an increasingly popular practice to diversify wine styles and/or to obtain more complex wines with a peculiar microbial footprint. One of the main interactions is competition for nutrients, especially nitrogen sources, that directly impacts not only fermentation performance but also the production of aroma compounds. In order to better understand the interactions taking place between non-Saccharomyces yeasts and S. cerevisiae during alcoholic fermentation, sequential inoculations of three yeast species (Pichia burtonii, Kluyveromyces marxianus, Zygoascus meyerae) with S. cerevisiae were performed individually in a synthetic medium. Different species-dependent interactions were evidenced. Indeed, the three sequential inoculations resulted in three different behaviors in terms of growth. P. burtonii and Z. meyerae declined after the inoculation of S. cerevisiae which promptly outcompeted the other two species. However, while the presence of P. burtonii did not impact the fermentation kinetics of S. cerevisiae, that of Z. meyerae rendered the overall kinetics very slow and with no clear exponential phase. K. marxianus and S. cerevisiae both declined and became undetectable before fermentation completion. The results also demonstrated that yeasts differed in their preference for nitrogen sources. Unlike Z. meyerae and P. burtonii, K. marxianus appeared to be a competitor for S. cerevisiae (as evidenced by the uptake of ammonium and amino acids), thereby explaining the resulting stuck fermentation. Nevertheless, the results suggested that competition for other nutrients (probably vitamins) occurred during the sequential inoculation of Z. meyerae with S. cerevisiae. The metabolic footprint of the non-Saccharomyces yeasts determined after 48 h of fermentation remained until the end of fermentation and combined with that of S. cerevisiae. For instance

  4. Repeated batch production of ethanol from Jerusalem artichoke tubers using recycled immobilized cells of Kluyveromyces fragilis

    Energy Technology Data Exchange (ETDEWEB)

    Margaritis, A.; Bajpai, P.

    1981-01-01

    Recycled immobilized cells of K. fragilis ATCC 28244 were used for repeated batch production of EtOH from the inulin sugars derived from Jerusalem artichoke tubers. Using 10% initial sugar concentration, a maximum EtOH concentration of 48 g/l was achieved in 7 h when the immobilized cell concentration in the Ca alginate beads was 72 g dry weight immobilized cell/l bioreactor vol.-h. The same Ca alginate beads containing the cells were used repeatedly for 11 batch runs starting with fresh medium at the beginning of each run. The EtOH yield was almost constant at 96% of the theoretical for all 11 batch runs, while the maximum EtOH production rate during the last batch run was 70% of the original EtOH rate obtained in the 1st batch run.

  5. Effects of Germination and Fermentation on the Functionality of Whole Soy Flour

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    Livia Patrascu

    2016-11-01

    Full Text Available Nutritional quality and technological performances of grains can be modulated through germination and controlled fermentation. The aim of the work was to estimate the effect of germination (72 h at 23oC and fermentation on the fundamental rheological properties of the soy flour based suspensions and sourdoughs, and to assess the bread making potential of the whole soy flours by considering the thermo-mechanical functionality of soy in admixture with white wheat flour. Soy flour based sourdough were prepared using three different starter cultures, consisting of mixtures of lactic acid bacteria like Lactobacillus plantarum, Lb. brevis, Lb. rhamnosus, Lb. casei, Lb. acidophilus, Bifidobacterium BB12®, and Streptococcus thermophilus and/or yeast Kluyveromyces marxianus subsp. Marxianus. The rheological behaviour of the suspensions and sourdoughs was influenced by the soy germination and fermentation processes. The stress sweep tests indicated significant narrowing of the linear viscoelastic regions, as well as the decrease of the stress values required for the beginning of flow. The temperature ramp test showed more intense swelling in case of the germinated and fermented samples. Both native and germinated soy flours were used to replace 15% of the wheat flour, and the Mixolab test indicated that the germination process caused the decrease of protein weakening and dough stability. The sourdoughs addition to the wheat flour resulted in significant changes of the thermo-mechanical properties of the dough. Properties related to stability of starch gel during heating, starch gelatinization and retrogradation depended on the type of starter culture used for fermentation.

  6. Taggiasca extra virgin olive oil colonization by yeasts during the extraction process.

    Science.gov (United States)

    Ciafardini, G; Cioccia, G; Zullo, B A

    2017-04-01

    The opalescent appearance of the newly produced olive oil is due to the presence of solid particles and microdrops of vegetation water in which the microorganisms from the olives' carposphere are trapped. Present research has demonstrated that the microbiota of the fresh extracted olive oil, produced in the mills, is mainly composed of yeasts and to a lesser extent of molds. The close link between the composition of the microbiota of the olives' carposphere undergoing to processing, and that of the microbiota of the newly produced olive oil, concerns only the yeasts and molds, given that the bacterial component is by and large destroyed mainly in the kneaded paste during the malaxation process. Six physiologically homogenous yeast groups were highlighted in the wash water, kneaded paste and newly produced olive oil from the Taggiasca variety which had been collected in mills located in the Liguria region. The more predominant yeasts of each group belonged to a single species called respectively: Kluyveromyces marxianus, Candida oleophila, Candida diddensiae, Candida norvegica, Wickerhamomyces anomalus and Debaryomyces hansenii. Apart from K. marxianus, which was found only in the wash water, all the other species were found in the wash water and in the kneaded paste as well as in the newly produced olive oil, while in the six-month stored olive oil, was found only one physiologically homogeneous group of yeast represented by the W. anomalus specie. These findings in according to our previous studies carried out on other types of mono varietal olive oils, confirms that the habitat of the Taggiascas' extra virgin olive oil, had a strong selective pressure on the yeast biota, allowing only to a few member of yeast species, contaminating the fresh product, to survive and reproduce in it during storage. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. MIKROFLORA PADA TEMPOYAK The Microflora of Tempoyak

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    Hasanuddin Hasanuddin

    2012-05-01

    Full Text Available Tempoyak is a traditional Bengkulu fermented food prepared from spontaneous fermentation of durian (Durio zibethi- nus by wild microorganisms. Tempoyak is found not only in Bengkulu but also as long as Sumatera island with differ- ent names, and also in Malaysia. Tempoyak is a Melayu term meaning fermented durian. The research was conducted to identify microflora in tempoyak, and to select the species of microorganisms which were able to ferment durian ef- fectivelly. The data in this study were laboratory analysis. Samples were collected weekly in a month from productions centre of tempoyak and traditional markets, and analyzed microbiologically to determine and identify the bacteria, yeasts and molds in tempoyak. There were four specieses of lactic acid bacteria found in fermented durian namely Pediococcus acidilactici, Lactobacillus plantarum Lactobacillus curvatus and Leuconostoc mesentroides. While two specieses which were not lactic acid bacteria namely Staphylococcus saprophyticus and Micrococcus varians. One species of yeast was Kluyveromyces marxianus. The molds were identified as Rhizopus oryzae, Monilia sitophila, Mucor roxii, Aspergillus repens and Penicillium sp. Among these specieses three specieses were produced lactic acid namelly Rhizopus oryzae, Monilia sitophila,and Mucor roxii. While Aspergillus ripens and Penicillium sp did not pro- duce lactic acid so these specieses might not function in fermentation process. ABSTRAK Tempoyak adalah makanan khas Bengkulu, yang dibuat dari fermentasi spontan daging buah durian (Durio zibet- hinus oleh mikroorganisme liar. Tempoyak juga bisa dijumpai di berbagai daerah Indonesia di sepanjang pulau Sumatera dengan nama yang berbeda, bahkan sampai ke Malaysia. Istilah tempoyak berasal dari terminolgi Melayu yang artinya adalah durian fermentasi. Penelitian ini bertujuan untuk mengidentifikasi mikroorganisme yang terdapat pada tempoyak. Data dari penelitian ini adalah data primer dari analisa

  8. Proceso de sacarificación y fermentación simultáneas para la conversión de la fracción celulósica del residuo de la extracción del aceite de oliva en etanol

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    Ballesteros, M.

    2002-09-01

    Full Text Available In this work, the residue generated in the new two-step centrifugation process for olive oil extraction is assessed for the production of bioethanol. Both olive pulp and fragmented stones fractions comprised in such residue are analyzed and tested at laboratory scale for bioconversion to ethanol by a simultaneous saccharification and fermentation (SSF process. Firstly, optima conditions for the enzymatic hydrolysis step of steam-exploded pretreated sustrates were determined. Then, simultaneous saccharification and fermentation process was assayed using the thermotolerant yeast Kluyveromyces marxianus in different assay conditions. For the selected conditions, 9 kg of unpretreated pulp or 6 kg of pretreated fragmented stones (both based on dry matter would be necessary to obtain 1 liter of ethanol.En el presente trabajo se estudia la producción de etanol-combustible a partir de la celulosa contenida en las distintas fracciones (pulpa y fragmentos de huesos que componen el residuo de la extracción de aceite de oliva mediante un proceso en dos fases. El trabajo ha consistido en una caracterización de las dos fracciones y en el estudio de la producción de etanol mediante un proceso de hidrólisis enzimática y fermentación simultáneas (SFS, a escala de laboratorio. Se ha estudiado el efecto que un pretratamiento termomecánico de explosión a vapor, previo a la etapa de hidrólisis enzimática y fermentación, tiene sobre la acción del complejo celulolítico. Por último, se han determinado las condiciones óptimas de ensayo para la sacarificación y fermentación simultáneas utilizando una cepa termotolerante de Kluyveromyces marxianus. En las condiciones de ensayo óptimas, serían necesarios 9 kg. de pulpa o 6 kg. de hueso pretratado (ambos sobre peso seco, para obtener 1 litro de etanol.

  9. Fine Structure of Tibetan Kefir Grains and Their Yeast Distribution, Diversity, and Shift

    Science.gov (United States)

    Lu, Man; Wang, Xingxing; Sun, Guowei; Qin, Bing; Xiao, Jinzhou; Yan, Shuling; Pan, Yingjie; Wang, Yongjie

    2014-01-01

    Tibetan kefir grains (TKGs), a kind of natural starter for fermented milk in Tibet, China, host various microorganisms of lactic acid bacteria, yeasts, and occasionally acetic acid bacteria in a polysaccharide/protein matrix. In the present study, the fine structure of TKGs was studied to shed light on this unusual symbiosis with stereomicroscopy and thin sections. The results reveal that TKGs consist of numerous small grain units, which are characterized by a hollow globular structure with a diameter between 2.0 and 9.0 mm and a wall thickness of approximately 200 µm. A polyhedron-like net structure, formed mainly by the bacteria, was observed in the wall of the grain units, which has not been reported previously to our knowledge. Towards the inside of the grain unit, the polyhedron-like net structures became gradually larger in diameter and fewer in number. Such fine structures may play a crucial role in the stability of the grains. Subsequently, the distribution, diversity, and shift of yeasts in TKGs were investigated based on thin section, scanning electron microscopy, cloning and sequencing of D1/D2 of the 26S rRNA gene, real-time quantitative PCR, and in situ hybridization with specific fluorescence-labeled oligonucleotide probes. These show that (i) yeasts appear to localize on the outer surface of the grains and grow normally together to form colonies embedded in the bacterial community; (ii) the diversity of yeasts is relatively low on genus level with three dominant species – Saccharomyces cerevisiae, Kluyveromyces marxianus, and Yarrowia lipolytica; (iii) S. cerevisiae is the stable predominant yeast species, while the composition of Kluyveromyces and Yarrowia are subject to change over time. Our results indicate that TKGs are relatively stable in structure, and culture conditions to some extent shape the microbial community and interaction in kefir grains. These findings pave the way for further study of the specific symbiotic associations between S

  10. Fine structure of Tibetan kefir grains and their yeast distribution, diversity, and shift.

    Directory of Open Access Journals (Sweden)

    Man Lu

    Full Text Available Tibetan kefir grains (TKGs, a kind of natural starter for fermented milk in Tibet, China, host various microorganisms of lactic acid bacteria, yeasts, and occasionally acetic acid bacteria in a polysaccharide/protein matrix. In the present study, the fine structure of TKGs was studied to shed light on this unusual symbiosis with stereomicroscopy and thin sections. The results reveal that TKGs consist of numerous small grain units, which are characterized by a hollow globular structure with a diameter between 2.0 and 9.0 mm and a wall thickness of approximately 200 µm. A polyhedron-like net structure, formed mainly by the bacteria, was observed in the wall of the grain units, which has not been reported previously to our knowledge. Towards the inside of the grain unit, the polyhedron-like net structures became gradually larger in diameter and fewer in number. Such fine structures may play a crucial role in the stability of the grains. Subsequently, the distribution, diversity, and shift of yeasts in TKGs were investigated based on thin section, scanning electron microscopy, cloning and sequencing of D1/D2 of the 26S rRNA gene, real-time quantitative PCR, and in situ hybridization with specific fluorescence-labeled oligonucleotide probes. These show that (i yeasts appear to localize on the outer surface of the grains and grow normally together to form colonies embedded in the bacterial community; (ii the diversity of yeasts is relatively low on genus level with three dominant species--Saccharomyces cerevisiae, Kluyveromyces marxianus, and Yarrowia lipolytica; (iii S. cerevisiae is the stable predominant yeast species, while the composition of Kluyveromyces and Yarrowia are subject to change over time. Our results indicate that TKGs are relatively stable in structure, and culture conditions to some extent shape the microbial community and interaction in kefir grains. These findings pave the way for further study of the specific symbiotic

  11. A Multiple-objective Optimization of Whey Fermentation in Stirred Tank Bioreactors

    Directory of Open Access Journals (Sweden)

    Mitko Petrov

    2006-12-01

    Full Text Available A multiple-objective optimization is applied to find an optimal policy of a fed-batch fermentation process for lactose oxidation from a natural substratum of the strain Kluyveromyces marxianus var. lactis MC5. The optimal policy is consisted of feed flow rate, agitation speed, and gas flow rate. The multiple-objective problem includes: the total price of the biomass production, the second objective functions are the separation cost in downstream processing and the third objective function corresponds to the oxygen mass-transfer in the bioreactor. The multiple-objective optimization are transforming to standard problem for optimization with single-objective function. Local criteria are defined utility function with different weight for single-type vector task. A fuzzy sets method is applied to be solved the maximizing decision problem. A simple combined algorithm guideline to find a satisfactory solution to the general multiple-objective optimization problem. The obtained optimal control results have shown an increase of the process productiveness and a decrease of the residual substrate concentration.

  12. Application of agave subproducts for production of microbial inulinases

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    Huerta Alcocer, S.A.

    2014-07-01

    Full Text Available Mexico is the center of origin of the genus Agave spp. with 159 endemic species, 75 % of all known species. The main use of these plants is in the production of alcoholic beverages, mainly tequila, which is obtained from the “pines” of A. tequilana Weber var. Azul. During tequila production, a huge amount of waste is produced, including leaves that are not used. Main compounds found in these subproducts are polysaccharides, specifically inulin. Current review focuses on the use of these agricultural wastes to obtain inulinase production, and in the production of high fructose syrup using these enzymes in these wastes. Currently, high fructose syrups, especially oligosaccharides, have prompted much interest for their benefits to health due to its low glycemic index and their function as prebiotic in the intestinal flora. The main microorganisms involved with inulinases production belong to the genera Aspergillus and Kluyveromyces. The latter is preferred in the industry due to its high growth rate, high temperature tolerance (52 °C and by having the GRAS (Generally Recognized As Safe status. This review emphasizes on the advances achieved in the production of inulinases by yeast K. marxianus.

  13. Genome and metabolic engineering in non-conventional yeasts: Current advances and applications

    Directory of Open Access Journals (Sweden)

    Ann-Kathrin Löbs

    2017-09-01

    Full Text Available Microbial production of chemicals and proteins from biomass-derived and waste sugar streams is a rapidly growing area of research and development. While the model yeast Saccharomyces cerevisiae is an excellent host for the conversion of glucose to ethanol, production of other chemicals from alternative substrates often requires extensive strain engineering. To avoid complex and intensive engineering of S. cerevisiae, other yeasts are often selected as hosts for bioprocessing based on their natural capacity to produce a desired product: for example, the efficient production and secretion of proteins, lipids, and primary metabolites that have value as commodity chemicals. Even when using yeasts with beneficial native phenotypes, metabolic engineering to increase yield, titer, and production rate is essential. The non-conventional yeasts Kluyveromyces lactis, K. marxianus, Scheffersomyces stipitis, Yarrowia lipolytica, Hansenula polymorpha and Pichia pastoris have been developed as eukaryotic hosts because of their desirable phenotypes, including thermotolerance, assimilation of diverse carbon sources, and high protein secretion. However, advanced metabolic engineering in these yeasts has been limited. This review outlines the challenges of using non-conventional yeasts for strain and pathway engineering, and discusses the developed solutions to these problems and the resulting applications in industrial biotechnology.

  14. Genome and metabolic engineering in non-conventional yeasts: Current advances and applications.

    Science.gov (United States)

    Löbs, Ann-Kathrin; Schwartz, Cory; Wheeldon, Ian

    2017-09-01

    Microbial production of chemicals and proteins from biomass-derived and waste sugar streams is a rapidly growing area of research and development. While the model yeast Saccharomyces cerevisia e is an excellent host for the conversion of glucose to ethanol, production of other chemicals from alternative substrates often requires extensive strain engineering. To avoid complex and intensive engineering of S. cerevisiae, other yeasts are often selected as hosts for bioprocessing based on their natural capacity to produce a desired product: for example, the efficient production and secretion of proteins, lipids, and primary metabolites that have value as commodity chemicals. Even when using yeasts with beneficial native phenotypes, metabolic engineering to increase yield, titer, and production rate is essential. The non-conventional yeasts Kluyveromyces lactis, K. marxianus, Scheffersomyces stipitis, Yarrowia lipolytica, Hansenula polymorpha and Pichia pastoris have been developed as eukaryotic hosts because of their desirable phenotypes, including thermotolerance, assimilation of diverse carbon sources, and high protein secretion. However, advanced metabolic engineering in these yeasts has been limited. This review outlines the challenges of using non-conventional yeasts for strain and pathway engineering, and discusses the developed solutions to these problems and the resulting applications in industrial biotechnology.

  15. Identification and Characterization of Oleaginous Yeast Isolated from Kefir and Its Ability to Accumulate Intracellular Fats in Deproteinated Potato Wastewater with Different Carbon Sources

    Science.gov (United States)

    Kieliszek, Marek; Jermacz, Karolina; Błażejak, Stanisław

    2017-01-01

    The search for efficient oleaginous microorganisms, which can be an alternative to fossil fuels and biofuels obtained from oilseed crops, has been going on for many years. The suitability of microorganisms in this regard is determined by their ability to biosynthesize lipids with preferred fatty acid profile along with the concurrent utilization of energy-rich industrial waste. In this study, we isolated, characterized, and identified kefir yeast strains using molecular biology techniques. The yeast isolates identified were Candida inconspicua, Debaryomyces hansenii, Kluyveromyces marxianus, Kazachstania unispora, and Zygotorulaspora florentina. We showed that deproteinated potato wastewater, a starch processing industry waste, supplemented with various carbon sources, including lactose and glycerol, is a suitable medium for the growth of yeast, which allows an accumulation of over 20% of lipid substances in its cells. Fatty acid composition primarily depended on the yeast strain and the carbon source used, and, based on our results, most of the strains met the criteria required for the production of biodiesel. In particular, this concerns a significant share of saturated fatty acids, such as C16:0 and C18:0, and unsaturated fatty acids, such as C18:1 and C18:2. The highest efficiency in lipid biosynthesis exceeded 6.3 g L−1. Kazachstania unispora was able to accumulate the high amount of palmitoleic acid. PMID:29098157

  16. Elucidation of new condition-dependent roles for fructose-1,6-bisphosphatase linked to cofactor balances.

    Directory of Open Access Journals (Sweden)

    Du Toit W P Schabort

    Full Text Available The cofactor balances in metabolism is of paramount importance in the design of a metabolic engineering strategy and understanding the regulation of metabolism in general. ATP, NAD+ and NADP+ balances are central players linking the various fluxes in central metabolism as well as biomass formation. NADP+ is especially important in the metabolic engineering of yeasts for xylose fermentation, since NADPH is required by most yeasts in the initial step of xylose utilisation, including the fast-growing Kluyveromyces marxianus. In this simulation study of yeast metabolism, the complex interplay between these cofactors was investigated; in particular, how they may affect the possible roles of fructose-1,6-bisphosphatase, the pentose phosphate pathway, glycerol production and the pyruvate dehydrogenase bypass. Using flux balance analysis, it was found that the potential role of fructose-1,6-bisphosphatase was highly dependent on the cofactor specificity of the oxidative pentose phosphate pathway and on the carbon source. Additionally, the excessive production of ATP under certain conditions might be involved in some of the phenomena observed, which may have been overlooked to date. Based on these findings, a strategy is proposed for the metabolic engineering of a future xylose-fermenting yeast for biofuel production.

  17. Modeling of an integrated fermentation/membrane extraction process for the production of 2-phenylethanol and 2-phenylethylacetate.

    Science.gov (United States)

    Adler, Philipp; Hugen, Thorsten; Wiewiora, Marzena; Kunz, Benno

    2011-03-07

    An unstructured model for an integrated fermentation/membrane extraction process for the production of the aroma compounds 2-phenylethanol and 2-phenylethylacetate by Kluyveromyces marxianus CBS 600 was developed. The extent to which this model, based only on data from the conventional fermentation and separation processes, provided an estimation of the integrated process was evaluated. The effect of product inhibition on specific growth rate and on biomass yield by both aroma compounds was approximated by multivariate regression. Simulations of the respective submodels for fermentation and the separation process matched well with experimental results. With respect to the in situ product removal (ISPR) process, the effect of reduced product inhibition due to product removal on specific growth rate and biomass yield was predicted adequately by the model simulations. Overall product yields were increased considerably in this process (4.0 g/L 2-PE+2-PEA vs. 1.4 g/L in conventional fermentation) and were even higher than predicted by the model. To describe the effect of product concentration on product formation itself, the model was extended using results from the conventional and the ISPR process, thus agreement between model and experimental data improved notably. Therefore, this model can be a useful tool for the development and optimization of an efficient integrated bioprocess. Copyright © 2010 Elsevier Inc. All rights reserved.

  18. Immobilization of yeast inulinase on chitosan beads for the hydrolysis of inulin in a batch system.

    Science.gov (United States)

    Singh, R S; Singh, R P; Kennedy, J F

    2017-02-01

    An extracellular inulinase was partially purified by ethanol precipitation and gel exclusion chromatography from a cell free extract of Kluyveromyces marxianus. Partially purified inulinase exhibited 420 IU/mg specific activity and it was immobilized on chitosan beads. Activity yield of immobilized inulinase was optimized with glutaraldehyde concentration (1-5%), glutaraldehyde treatment time (30-240min), enzyme coupling-time (2-16h) and enzyme loading (5-30 IU) as functions. Under the optimized conditions maximum yield 65.5% of immobilized inulinase was obtained. Maximum hydrolysis of inulin 84.5% and 78.2% was observed at 125rpm after 4h by immobilized and free enzyme, respectively. A retention-time of 4h and 5h was found optimal for the hydrolysis of inulin under agitation (125rpm) by free and immobilized enzyme, respectively. The recycling of the developed immobilized biocatalyst was carried out after 5h of inulin hydrolysis in a batch system. The developed immobilized biocatalyst was successfully used for the hydrolysis of inulin for 14 batches. This is the first report on the immobilization of yeast inulinase on chitosan beads for the hydrolysis of inulin in a batch system. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. The evaluation of kefir pure culture starter: Liquid-core capsule entrapping microorganisms isolated from kefir grains.

    Science.gov (United States)

    Wang, Liang; Zhong, Hao; Liu, Keying; Guo, Aizhen; Qi, Xianghui; Cai, Meihong

    2016-10-01

    The main purpose of this study was to develop a pure culture starter for producing kefir. In order to accomplish starter recycling, yeasts (Kluyveromyces marxianus strain, Pichia kudriavzevii clone), lactic acid bacteria (Lactobacillus kefiri strain F4Aa, Lactobacillus kefiri strain NM131-7, Lactobacillus kefiri strain NM132-3, Lactobacillus kefiri strain NM180-3, respectively), and acetic acid bacteria (Acetobacter lovaniensis strain) were entrapped in liquid core capsules based on the distribution ratio in kefir grains. The microbiological, antimicrobial, and chemical properties of kefir made with capsules (M) and kefir grains (K) were measured and compared. According to the results of plate counts in different selective medium, the number of yeasts and bacteria in the liquid core capsules gradually increased and stabilized after eight fermentation cycles. The results of gas chromatography-mass spectrometry showed that almost all the aroma components existed in the two type of kefir, except the ethyl lactate. There was no significant difference in alcohol content, protein content, and fat content, except the acidity and sugar content. Water holding capacity of kefir K was higher than kefir M. There were 14 same free amino acids in kefir M and kefir K, and the content of most free amino acids was similar. In antimicrobial test, there was no significant difference in both kefirs. © The Author(s) 2016.

  20. Identification and Characterization of Oleaginous Yeast Isolated from Kefir and Its Ability to Accumulate Intracellular Fats in Deproteinated Potato Wastewater with Different Carbon Sources

    Directory of Open Access Journals (Sweden)

    Iwona Gientka

    2017-01-01

    Full Text Available The search for efficient oleaginous microorganisms, which can be an alternative to fossil fuels and biofuels obtained from oilseed crops, has been going on for many years. The suitability of microorganisms in this regard is determined by their ability to biosynthesize lipids with preferred fatty acid profile along with the concurrent utilization of energy-rich industrial waste. In this study, we isolated, characterized, and identified kefir yeast strains using molecular biology techniques. The yeast isolates identified were Candida inconspicua, Debaryomyces hansenii, Kluyveromyces marxianus, Kazachstania unispora, and Zygotorulaspora florentina. We showed that deproteinated potato wastewater, a starch processing industry waste, supplemented with various carbon sources, including lactose and glycerol, is a suitable medium for the growth of yeast, which allows an accumulation of over 20% of lipid substances in its cells. Fatty acid composition primarily depended on the yeast strain and the carbon source used, and, based on our results, most of the strains met the criteria required for the production of biodiesel. In particular, this concerns a significant share of saturated fatty acids, such as C16:0 and C18:0, and unsaturated fatty acids, such as C18:1 and C18:2. The highest efficiency in lipid biosynthesis exceeded 6.3 g L−1. Kazachstania unispora was able to accumulate the high amount of palmitoleic acid.

  1. Identification and Characterization of Oleaginous Yeast Isolated from Kefir and Its Ability to Accumulate Intracellular Fats in Deproteinated Potato Wastewater with Different Carbon Sources.

    Science.gov (United States)

    Gientka, Iwona; Kieliszek, Marek; Jermacz, Karolina; Błażejak, Stanisław

    2017-01-01

    The search for efficient oleaginous microorganisms, which can be an alternative to fossil fuels and biofuels obtained from oilseed crops, has been going on for many years. The suitability of microorganisms in this regard is determined by their ability to biosynthesize lipids with preferred fatty acid profile along with the concurrent utilization of energy-rich industrial waste. In this study, we isolated, characterized, and identified kefir yeast strains using molecular biology techniques. The yeast isolates identified were Candida inconspicua , Debaryomyces hansenii , Kluyveromyces marxianus , Kazachstania unispora , and Zygotorulaspora florentina . We showed that deproteinated potato wastewater, a starch processing industry waste, supplemented with various carbon sources, including lactose and glycerol, is a suitable medium for the growth of yeast, which allows an accumulation of over 20% of lipid substances in its cells. Fatty acid composition primarily depended on the yeast strain and the carbon source used, and, based on our results, most of the strains met the criteria required for the production of biodiesel. In particular, this concerns a significant share of saturated fatty acids, such as C16:0 and C18:0, and unsaturated fatty acids, such as C18:1 and C18:2. The highest efficiency in lipid biosynthesis exceeded 6.3 g L -1 . Kazachstania unispora was able to accumulate the high amount of palmitoleic acid.

  2. Steam explosion treatment for ethanol production from branches pruned from pear trees by simultaneous saccharification and fermentation.

    Science.gov (United States)

    Sasaki, Chizuru; Okumura, Ryosuke; Asada, Chikako; Nakamura, Yoshitoshi

    2014-01-01

    This study investigated the production of ethanol from unutilized branches pruned from pear trees by steam explosion pretreatment. Steam pressures of 25, 35, and 45 atm were applied for 5 min, followed by enzymatic saccharification of the extracted residues with cellulase (Cellic CTec2). High glucose recoveries, of 93.3, 99.7, and 87.1%, of the total sugar derived from the cellulose were obtained from water- and methanol-extracted residues after steam explosion at 25, 35, and 45 tm, respectively. These values corresponded to 34.9, 34.3, and 27.1 g of glucose per 100 g of dry steam-exploded branches. Simultaneous saccharification and fermentation experiments were done on water-extracted residues and water- and methanol-extracted residues by Kluyveromyces marxianus NBRC 1777. An overall highest theoretical ethanol yield of 76% of the total sugar derived from cellulose was achieved when 100 g/L of water- and methanol-washed residues from 35 atm-exploded pear branches was used as substrate.

  3. Screening of Jerusalem artichoke varieties for bio-ethanol production in Portugal

    Energy Technology Data Exchange (ETDEWEB)

    Passarinho, P.C.; Oliveira, A.C.; Rosa, M.F. [INETI, Departamento de Energias Renovaveis, Estrada do Paco do Lumiar, Ed. G, 1649-038, Lisboa (Portugal)

    2008-07-01

    The aim of this work was the evaluation of the potential of 9 Jerusalem artichoke varieties for the sustainable production of bio-ethanol in Portugal. The tubers, which are the part of the plant with higher sugar content, were harvested at different stages of development (29 to 55 weeks), and crashed for juice extraction. The two phases obtained were characterized in terms of total sugars, protein, ash and dry matter. The ethanol productivity of the different J. artichoke varieties was then evaluated fermenting juice or mixtures of juice and pulp aqueous extract with a strain of Kluyveromyces marxianus, a yeast able to hydrolyze and ferment inulin polymers. The chamical characteristic more dependable on the harvest period was the amount of total sugars in the tubers. Juices, obtained until 48 weeks development, contained 173 - 235 g/L of total sugars while juices from the last harvest presented markedly lower sugar contents, indicating crop degradation or sugar migration to the soil. Regarding the fermentative process, ethanol yields ranged from 0.3 to 0.5 g/g. The main conclusion of this work indicates C13 variety as the best. Although bearing a lower sugar concentration in tubers, the substantially higher agricultural productivities (kg/m2) after 8 months growing allowed to estimate productions higher than 10 000 L/ha.

  4. Yeast derived from lignocellulosic biomass as a sustainable feed resource for use in aquaculture.

    Science.gov (United States)

    Øverland, Margareth; Skrede, Anders

    2017-02-01

    The global expansion in aquaculture production implies an emerging need of suitable and sustainable protein sources. Currently, the fish feed industry is dependent on high-quality protein sources of marine and plant origin. Yeast derived from processing of low-value and non-food lignocellulosic biomass is a potential sustainable source of protein in fish diets. Following enzymatic hydrolysis, the hexose and pentose sugars of lignocellulosic substrates and supplementary nutrients can be converted into protein-rich yeast biomass by fermentation. Studies have shown that yeasts such as Saccharomyces cerevisiae, Candida utilis and Kluyveromyces marxianus have favourable amino acid composition and excellent properties as protein sources in diets for fish, including carnivorous species such as Atlantic salmon and rainbow trout. Suitable downstream processing of the biomass to disrupt cell walls is required to secure high nutrient digestibility. A number of studies have shown various immunological and health benefits from feeding fish low levels of yeast and yeast-derived cell wall fractions. This review summarises current literature on the potential of yeast from lignocellulosic biomass as an alternative protein source for the aquaculture industry. It is concluded that further research and development within yeast production can be important to secure the future sustainability and economic viability of intensive aquaculture. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  5. Evaluation of hyper thermal acid hydrolysis of Kappaphycus alvarezii for enhanced bioethanol production.

    Science.gov (United States)

    Ra, Chae Hun; Nguyen, Trung Hau; Jeong, Gwi-Taek; Kim, Sung-Koo

    2016-06-01

    Hyper thermal (HT) acid hydrolysis of Kappaphycus alvarezii, a red seaweed, was optimized to 12% (w/v) seaweed slurry content, 180mM H2SO4 at 140°C for 5min. The maximum monosaccharide concentration of 38.3g/L and 66.7% conversion from total fermentable monosaccharides of 57.6g/L with 120gdw/L K. alvarezii slurry were obtained from HT acid hydrolysis and enzymatic saccharification. HT acid hydrolysis at a severity factor of 0.78 efficiently converted the carbohydrates of seaweed to monosaccharides and produced a low concentration of inhibitory compounds. The levels of ethanol production by separate hydrolysis and fermentation with non-adapted and adapted Kluyveromyces marxianus to high concentration of galactose were 6.1g/L with ethanol yield (YEtOH) of 0.19 at 84h and 16.0g/L with YEtOH of 0.42 at 72h, respectively. Development of the HT acid hydrolysis process and adapted yeast could enhance the overall ethanol fermentation yields of K. alvarezii seaweed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Contribution to interpretation of metal uptake dependence upon the growth phase of microorganisms. The case of uranium (VI) uptake by common yeasts, cultivated at different temperatures, with or without aeration

    International Nuclear Information System (INIS)

    Anagnostopoulos, V.A.; Symeopoulos, B.D.; Argyro Bekatorou

    2011-01-01

    The dependence of U(VI) uptake on the temperature of cell culture, the air flow during the cultivation process and the age of cells were studied. Saccharomyces cerevisiae, Kluyveromyces marxianus and Debaromyces hansenii were chosen as typical yeasts, which are widely used, in food industries. Our results revealed that the highest metal uptake was obtained from exponential phase cells, which had been cultivated at the optimum temperature of growth, while the air flow during the cultivation process, exhibited no significant effect on the metal uptake. A qualitative interpretation of bibliographic data, concerning the metal uptake on the age of cells is proposed, assuming that qualitative changes in the cell wall structure take place, as the cells pass from exponential to stationary phase, in addition to quantitative modifications, which have been reported in the literature. According to our interpretation, the relative abundances among quantitative and qualitative alterations of cell wall, determine which cells (exponential or stationary) exhibit the higher metal capacity. One type of the suggested qualitative modifications of surface constituent of cell wall, may have been caused by a shortening of a carboxylic acid carbon chain. This type of modification implies, as prerequisite, the decrease of pK a values of cell wall carboxyl groups, with the age of cells. An evidence, supporting our approach, may be the fact that the decrease of pK a values mentioned above, has been observed by other authors. (author)

  7. Transgalactosylation/Hydrolysis Ratios of Various β-Galactosidases Catalyzing Alkyl-β-Galactoside Synthesis in Single-Phased Alcohol Media

    Directory of Open Access Journals (Sweden)

    Eleonora Winkelhausen

    2008-01-01

    Full Text Available Three microbial galactosidases, Aspergillus oryzae, Escherichia coli and Kluyveromyces marxianus β-galactosidase, were used as catalysts for transgalactosylation synthesis of alkyl-β-galactosides in single-phased alcohol media. Their selectivity towards different alcohol nucleophiles was quantified by determining the transgalactosylation/hydrolysis ratio in the water/alcohol mixtures containing water in concentrations below the level of saturation. p-Nitrophenyl-β-galactoside was used as a glycosyl donor at a concentration of 10 mM. Both the total reaction rate (transgalactosylation+hydrolysis and the ratio between the transgalactosylation (alcoholysis and hydrolysis increased with the increase of water activity. Although the A. oryzae β-galactosidase showed relatively low total activity (3.13 μmol/(min·mg protein, it exhibited the highest selectivity towards the hexanol nucleophile among the examined enzymes (0.65. The selectivity values in all the examined cases were below one, which implies that the hydrolysis, and not the synthesis, was the dominating reaction. The total reaction rate (transgalactosylation+hydrolysis was strongly affected by the water activity, and for the specific water activity in the different alcohols, it increased in the following order: n-octanol, n-hexanol, n-butanol.

  8. Bio-ethanol production by fermentation of ricotta cheese whey as an effective alternative non-vegetable source

    Energy Technology Data Exchange (ETDEWEB)

    Sansonetti, Sascha; Curcio, Stefano; Calabro, Vincenza; Iorio, Gabriele [Department of Engineering Modeling, University of Calabria, Ponte P. Bucci, Cubo 42/A, 87036 Rende, Cosenza (Italy)

    2009-12-15

    The aim of the present paper is to investigate the feasibility of bio-ethanol production by batch fermentation of ricotta cheese whey (''Scotta''), a dairy industry waste characterized by lactose concentration ranging from 4.5% to 5.0% (w/w) and, with respect to traditional (raw) whey, by much lower protein content. Scotta, therefore, could represent an effective non-vegetable source for renewable energy production. The microrganism used to carry out the fermentation processes was the yeast Kluyveromyces marxianus. Preliminary experiments, performed in aerobic conditions on different volumes of scotta, have shown the actual growth of the yeast. The subsequent fermentation experiments were carried out, in anaerobic conditions, on three different substrates: scotta, raw cheese whey and deproteinized whey. The experimental data have demonstrated the process feasibility: scotta is an excellent substrate for fermentation and exhibits better performance with respect to both raw cheese whey and deproteinized whey. Complete lactose consumption, indeed, was observed in the shortest time (13 h) and with the highest ethanol yield (97% of the theoretical value). (author)

  9. Occurrence of mycotoxins and yeasts and moulds identification in corn silages in tropical climate.

    Science.gov (United States)

    Carvalho, B F; Ávila, C L S; Krempser, P M; Batista, L R; Pereira, M N; Schwan, R F

    2016-05-01

    This study was aimed to identify yeasts and moulds as well as to detect mycotoxin in corn silages in southern Minas Gerais, Brazil. Corn silages from 36 farms were sampled to analyse dry matter, crude protein, ether extract, ash, neutral detergent fibre, nonfibre carbohydrates and mycotoxins contents, yeasts and moulds population, pH and temperature values. The mycotoxins found in high frequency were aflatoxin in 77·7% of analysed samples, ochratoxin (33·3%) and zearalenone (22·2%). There was no significant correlation between the mycotoxin concentration and the presence of moulds. The pH was negatively correlated with ochratoxin concentration. Aspergillus fumigatus was identified in all silages that presented growth of moulds. Ten different yeast species were identified using the culture-dependent method: Candida diversa, Candida ethanolica, Candida rugosa, Issatchenkia orientalis, Kluyveromyces marxianus, Pichia manshurica, Pichia membranifaciens, Saccharomyces cerevisiae, Trichosporon asahii and Trichosporon japonicum. Another six different yeast species were identified using the culture-independent method. A high mycotoxin contamination rate (91·6% of the analysed silages) was observed. The results indicated that conventional culturing and PCR-DGGE should be combined to optimally describe the microbiota associated with corn silage. This study provides information about the corn silage fermentation dynamics and our findings are relevant to optimization of this silage fermentation. © 2016 The Society for Applied Microbiology.

  10. Production of yeast biomass using waste Chinese cabbage

    Energy Technology Data Exchange (ETDEWEB)

    Min Ho Choi; Yun Hee Park [Ajou Univ., Suwon (Korea). Dept. of Molecular Science and Technology

    2003-08-01

    The possibility of using waste Chinese cabbage as a substrate for microbial biomass production was investigated. Cell mass and the protein content of four species of yeast, Candida utilis, Pichia stipitis, Kluyveromyces marxianus, and Saccharomyces cerevisiae, were determined when cultured in juice extracted from cabbage waste. Compared to YM broth containing the same level of sugar, all the strains except C. utilis showed higher total protein production in cabbage juice medium (CJM). Cell mass production was lower for all four strains in heat-treated CJM than in membrane-filtered medium, and this adverse effect was pronounced when the CJM was autoclaved at 121{sup o}C for 15 min. As a source of inorganic nitrogen, only ammonium sulfate added at a concentration of 0.5 g nitrogen per liter of CJM increased cell growth. Of the seven organic nitrogen sources tested, only corn steep powder was effective in increasing cell mass (by about 11%). As a micronutrient, the addition of 0.5 mM zinc increased cell mass. The results suggest that juice from waste Chinese cabbages can be used to produce microbial biomass protein without substantial modification, after preliminary heat treatment at temperatures below those required for sterilization. (Author)

  11. Bioethanol production from Scenedesmus obliquus sugars. The influence of photobioreactors and culture conditions on biomass production

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, J.R.; Passarinho, P.C.; Gouveia, L. [Laboratorio Nacional de Energia e Geologia (LNEG), Lisbon (Portugal). Unidade de Bioenergia

    2012-10-15

    A closed-loop vertical tubular photobioreactor (PBR), specially designed to operate under conditions of scarce flat land availability and irregular solar irradiance conditions, was used to study the potential of Scenedesmus obliquus biomass/sugar production. The results obtained were compared to those from an open-raceway pond and a closed-bubble column. The influence of the type of light source and the regime (natural vs artificial and continuous vs light/dark cycles) on the growth of the microalga and the extent of the sugar accumulation was studied in both PBRs. The best type of reactor studied was a closed-loop PBR illuminated with natural light/dark cycles. In all the cases, the relationship between the nitrate depletion and the sugar accumulation was observed. The microalga Scenedesmus was cultivated for 53 days in a raceway pond (4,500 L) and accumulated a maximum sugar content of 29 % g/g. It was pre-treated for carrying out ethanol fermentation assays, and the highest ethanol concentration obtained in the hydrolysate fermented by Kluyveromyces marxianus was 11.7 g/L. (orig.)

  12. Maximization of beta-galactosidase production: a simultaneous investigation of agitation and aeration effects.

    Science.gov (United States)

    Alves, Fernanda Germano; Filho, Francisco Maugeri; de Medeiros Burkert, Janaína Fernandes; Kalil, Susana Juliano

    2010-03-01

    In this work, the agitation and aeration effects in the maximization of the beta-galactosidase production from Kluyveromyces marxianus CCT 7082 were investigated simultaneously, in relation to the volumetric enzyme activity and the productivity, as well as the analysis of the lactose consumption and production of glucose, and galactose of this process. Agitation and aeration effects were studied in a 2 L batch stirred reactor. A central composite design (2(2) trials plus three central points) was carried out. Agitation speed varied from 200 to 500 rpm and aeration rate from 0.5 to 1.5 vvm. It has been shown in this study that the volumetric enzyme production was strongly influenced by mixing conditions, while aeration was shown to be less significant. Linear models for activity and productivity due to agitation and aeration were obtained. The favorable condition was 500 rpm and 1.5 vvm, which lead to the best production of 17 U mL(-1) for enzymatic activity, 1.2 U mL(-1) h(-1) for productivity in 14 h of process, a cellular concentration of 11 mg mL(-1), and a 167.2 h(-1) volumetric oxygen transfer coefficient.

  13. The occurrence and growth of yeasts in Camembert and blue-veined cheeses.

    Science.gov (United States)

    Roostita, R; Fleet, G H

    1996-01-01

    Yeast populations greater than 10(6) cfu/g were found in approximately 54% and 36%, respectively in surface samples of retail Camembert (85 samples) and Blue-veined (45 samples) cheeses. The most predominant species isolated were Debaryomyces hansenii, Candida catenulata, C. lipolytica, C. kefyr, C. intermedia, Saccharomyces cerevisiae, Cryptococcus albidus and Kluyveromyces marxianus. The salt concentration of the surface samples of the cheeses varied between 2.5-5.5% (w/w) (Camembert) and 7.5-8.3 (Blue-veined), depending upon brand, and influenced the yeast ecology, especially the presence of S. cerevisiae. Yeasts grew to populations of 10(6)-10(8) cfu/g when cheeses were stored at either 25 degrees C or 10 degrees C. These populations decreased on continued storage at 25 degrees C, but such decreases were not so evident on storage at 10 degrees C. The properties of yeasts influencing their occurrence and growth in cheese were: fermentation/assimilation of lactose; production of extracellular lipolytic and proteolytic enzymes, utilisation of lactic and citric acids; and growth at 10 degrees C.

  14. Continuous production of pectinase by immobilized yeast cells on spent grains.

    Science.gov (United States)

    Almeida, Catarina; Brányik, Tomás; Moradas-Ferreira, Pedro; Teixeira, José

    2003-01-01

    A yeast strain secreting endopolygalacturonase was used in this work to study the possibility of continuous production of this enzyme. It is a feasible and interesting alternative to fungal batch production essentially due to the specificity of the type of pectinase excreted by Kluyveromyces marxianus CCT 3172, to the lower broth viscosity and to the easier downstream operations. In order to increase the reactors' productivity, a cellulosic carrier obtained from barley spent grains was tested as an immobilization support. Two types of reactors were studied for pectinase production using glucose as a carbon and energy source--a continuous stirred tank reactor (CSTR) and a packed bed reactor (PBR) with recycled flow. The highest value for pectinase volumetric productivity (P(V)=0.98 U ml(-1) h(-1)) was achieved in the PBR for D=0.40 h(-1), a glucose concentration on the inlet of S(in)=20 g l(-1), and a biomass load in the support of X(i)=0.225 g g(-1). The results demonstrate the attractiveness of the packed bed system for pectinase production.

  15. Bioethanol production from Scenedesmus obliquus sugars: the influence of photobioreactors and culture conditions on biomass production.

    Science.gov (United States)

    Miranda, J R; Passarinho, P C; Gouveia, L

    2012-10-01

    A closed-loop vertical tubular photobioreactor (PBR), specially designed to operate under conditions of scarce flat land availability and irregular solar irradiance conditions, was used to study the potential of Scenedesmus obliquus biomass/sugar production. The results obtained were compared to those from an open-raceway pond and a closed-bubble column. The influence of the type of light source and the regime (natural vs artificial and continuous vs light/dark cycles) on the growth of the microalga and the extent of the sugar accumulation was studied in both PBRs. The best type of reactor studied was a closed-loop PBR illuminated with natural light/dark cycles. In all the cases, the relationship between the nitrate depletion and the sugar accumulation was observed. The microalga Scenedesmus was cultivated for 53 days in a raceway pond (4,500 L) and accumulated a maximum sugar content of 29 % g/g. It was pre-treated for carrying out ethanol fermentation assays, and the highest ethanol concentration obtained in the hydrolysate fermented by Kluyveromyces marxianus was 11.7 g/L.

  16. Yeast Biomass Production in Brewery's Spent Grains Hemicellulosic Hydrolyzate

    Science.gov (United States)

    Duarte, Luís C.; Carvalheiro, Florbela; Lopes, Sónia; Neves, Ines; Gírio, Francisco M.

    Yeast single-cell protein and yeast extract, in particular, are two products which have many feed, food, pharmaceutical, and biotechnological applications. However, many of these applications are limited by their market price. Specifically, the yeast extract requirements for culture media are one of the major technical hurdles to be overcome for the development of low-cost fermentation routes for several top value chemicals in a biorefinery framework. A potential biotechnical solution is the production of yeast biomass from the hemicellulosic fraction stream. The growth of three pentose-assimilating yeast cell factories, Debaryomyces hansenii, Kluyveromyces marxianus, and Pichia stipitis was compared using non-detoxified brewery's spent grains hemicellulosic hydrolyzate supplemented with mineral nutrients. The yeasts exhibited different specific growth rates, biomass productivities, and yields being D. hansenii as the yeast species that presented the best performance, assimilating all sugars and noteworthy consuming most of the hydrolyzate inhibitors. Under optimized conditions, D. hansenii displayed a maximum specific growth rate, biomass yield, and productivity of 0.34 h-1, 0.61 g g-1, and 0.56 g 1-1 h-1, respectively. The nutritional profile of D. hansenii was thoroughly evaluated, and it compares favorably to others reported in literature. It contains considerable amounts of some essential amino acids and a high ratio of unsaturated over saturated fatty acids.

  17. Phytase-producing capacity of yeasts isolated from traditional African fermented food products and PHYPk gene expression of Pichia kudriavzevii strains.

    Science.gov (United States)

    Greppi, Anna; Krych, Łukasz; Costantini, Antonella; Rantsiou, Kalliopi; Hounhouigan, D Joseph; Arneborg, Nils; Cocolin, Luca; Jespersen, Lene

    2015-07-16

    Phytate is known as a strong chelate of minerals causing their reduced uptake by the human intestine. Ninety-three yeast isolates from traditional African fermented food products, belonging to nine species (Pichia kudriavzevii, Saccharomyces cerevisiae, Clavispora lusitaniae, Kluyveromyces marxianus, Millerozyma farinosa, Candida glabrata, Wickerhamomyces anomalus, Hanseniaspora guilliermondii and Debaryomyces nepalensis) were screened for phytase production on solid and liquid media. 95% were able to grow in the presence of phytate as sole phosphate source, P. kudriavzevii being the best growing species. A phytase coding gene of P. kudriavzevii (PHYPk) was identified and its expression was studied during growth by RT-qPCR. The expression level of PHYPk was significantly higher in phytate-medium, compared to phosphate-medium. In phytate-medium expression was seen in the lag phase. Significant differences in gene expression were detected among the strains as well as between the media. A correlation was found between the PHYPk expression and phytase extracellular activity. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Hydrolysis of whey by whole cells of Kluyveromyces bulgaricus immobilized in calcium alginate gels in hen egg white

    Energy Technology Data Exchange (ETDEWEB)

    Decleire, M; Huynh, N van; Motte, J C; Cat, W de

    1985-10-01

    Whey hydrolysis was compared in column reactors containing whole yeast cells immobilized in Ca-alginate or in hen egg white in relation to cell US -galactosidase activity, flow rates, temperature and time. With cells of 1.3 U/mg dry weight (ONPG method) immobilized in Ca-alignate, 80% hydrolysis was obtained at 4 and 20C with, respectively 0.50 and 1.65 bed volume/H; the values were 0.2 and 0.74 with cells entrapped in hen egg white. When the flow rate was expressed as ml/H/g wet yeast, no significant difference was observed between both matrices and 80% hydrolysis was reached with a flow rate 1.7 and 5 according to the temperature. The best performance was achieved by the yeast egg white reactor. At 4C, hydrolysis deccreased by 10% after 13 days; by 20% after 17 days. The presence of lactose transport inhibitors in whey did not significantly influence lactose hydrolysis. (orig.).

  19. Saccharomyces cerevisiae Bat1 and Bat2 aminotransferases have functionally diverged from the ancestral-like Kluyveromyces lactis orthologous enzyme.

    Directory of Open Access Journals (Sweden)

    Maritrini Colón

    Full Text Available BACKGROUND: Gene duplication is a key evolutionary mechanism providing material for the generation of genes with new or modified functions. The fate of duplicated gene copies has been amply discussed and several models have been put forward to account for duplicate conservation. The specialization model considers that duplication of a bifunctional ancestral gene could result in the preservation of both copies through subfunctionalization, resulting in the distribution of the two ancestral functions between the gene duplicates. Here we investigate whether the presumed bifunctional character displayed by the single branched chain amino acid aminotransferase present in K. lactis has been distributed in the two paralogous genes present in S. cerevisiae, and whether this conservation has impacted S. cerevisiae metabolism. PRINCIPAL FINDINGS: Our results show that the KlBat1 orthologous BCAT is a bifunctional enzyme, which participates in the biosynthesis and catabolism of branched chain aminoacids (BCAAs. This dual role has been distributed in S. cerevisiae Bat1 and Bat2 paralogous proteins, supporting the specialization model posed to explain the evolution of gene duplications. BAT1 is highly expressed under biosynthetic conditions, while BAT2 expression is highest under catabolic conditions. Bat1 and Bat2 differential relocalization has favored their physiological function, since biosynthetic precursors are generated in the mitochondria (Bat1, while catabolic substrates are accumulated in the cytosol (Bat2. Under respiratory conditions, in the presence of ammonium and BCAAs the bat1Δ bat2Δ double mutant shows impaired growth, indicating that Bat1 and Bat2 could play redundant roles. In K. lactis wild type growth is independent of BCAA degradation, since a Klbat1Δ mutant grows under this condition. CONCLUSIONS: Our study shows that BAT1 and BAT2 differential expression and subcellular relocalization has resulted in the distribution of the biosynthetic and catabolic roles of the ancestral BCAT in two isozymes improving BCAAs metabolism and constituting an adaptation to facultative metabolism.

  20. Reaction kinetics and galactooligosaccharide product profiles of the β-galactosidases from Bacillus circulans, Kluyveromyces lactis and Aspergillus oryzae

    NARCIS (Netherlands)

    Yin, Huifang; Bultema, Jelle B; Dijkhuizen, Lubbert; van Leeuwen, Sander S

    2017-01-01

    β-Galactosidase enzymes are used in the dairy industry to convert lactose into galactooligosaccharides (GOS) that are added to infant formula to mimic the molecular sizes and prebiotic functions of human milk oligosaccharides. Here we report a detailed analysis of the clearly different GOS profiles

  1. β-1,3 Glucanases e quitinases: aplicação na lise de leveduras e inibição de fungos β-1,3 glucanases and chitinases: application in the yeast cell lysis and fungi inhibition

    Directory of Open Access Journals (Sweden)

    Luciana Francisco Fleuri

    2008-08-01

    Full Text Available Objetivou-se, no presente trabalho, a aplicação de β-1,3 glucanases e quitinases da linhagem Cellulosimicrobium cellulans 191 na lise de leveduras e inibição de fungos, respectivamente. O delineamento experimental mostrou que as melhores condições para a lise de Saccharomyces cerevisiae KL-88 pela β-1,3 glucanase foi pH 6,5 e 35ºC. As células de leveduras incubadas por 10 h em frascos sem agitação mostraram-se mais susceptíveis à lise pela ação da enzima. Foi obtido maior lise da levedura quando a suspensão de células foi submetida ao tratamento com β-1,3 glucanase e cisteína 1mM. A enzima invertase intracelular ou ligada à célula de S. cerevisiae KL-88 e K. marxianus NCYC 587 foi extraída após tratamento da suspensão celular com β-1,3 glucanase, sendo que o tratamento prévio das leveduras com a enzima aumentou a susceptibilidade das células à lise com ultra-som. A preparação de quitinase foi capaz de formar halos de inibição de alguns fungos.The aim of this work was the application of β-1,3 glucanases and chitinases by Cellulosimicrobium cellulans 191 strain on yeast cell lysis and fungi inhibition, respectively. The experimental design study showed that the best conditions to Saccharomyces cerevisiae KL-88 lysis by β-1,3 glucanase extract were pH 6,5 and 35ºC. This study also demonstrated that the yeast cells were more susceptible to lysis after 10 h of cultivation in flasks without agitation. Lysis activity was increased when S. cerevisiae KL-88 cell suspension was treated with β-1,3 glucanase and cystein 1mM. The enzyme invertase of S. cerevisiae KL-88 and Kluyveromyces marxianus NCYC 587 was extracted after treatment of cell suspension with β-1,3 glucanase and the previous treatment of yeasts with the enzyme, increased the susceptibility to lysis when ultrasonic treatment was used. The chitinase presented growth inhibition halos for some of the fungi.

  2. Implementación de una línea de evaluación para subproductos agroindustriales como sustrato para la producción de bioetanol. Presacarificación-sacarificación/fermentación simultánea

    Directory of Open Access Journals (Sweden)

    Mary Lopretti

    2011-05-01

    Full Text Available El estudio de vías alternativas con mayores rendimientos y bajos costos es en estos días el foco de estudio en el tema Bioetanol, por tal motivo, en el presente trabajo se utilizaron dos cepas de hongos filamentosos; Trichoderma harzianum y Pleurotus ostreatus, actuando en diferentes sustratos residuales; orujo de uva, aserrín y torta de girasol provenientes de diferentes industrias nacionales, con el fin de establecer un sistema de evaluación de procesos conjuntos para la producción de alcohol a partir de microorganismos lignocelulósicos. En el diseño de estudio se contemplan la realización de una Presacarificación, con el objetivo de predigerir los sustratos, de forma de homogeneizar los diferentes sustratos acortando de esta forma las etapas posteriores; una Sacarificación enzimática utilizando el extracto de celulasas fúngicas obtenidas por Fermentación semi sólida en el proceso de Presacarificación; y un proceso de Fermentación, el cual involucra un microorganismo termoestable; Kluyveromyces marxianus (NRRL Y-665, de tal forma que permita reunir los procesos de Sacarificación y Fermentación en forma simultánea.De acuerdo a los resultados obtenidos podemos establecer que el sistema empleado de FSS previa presacarificación es un buen sistema para la producción de azúcares fermentables y alcohol. Los estudios comparativos realizados con diferentes sustratos demuestran que cuando el soporte es orujo de uva o torta de girasol, se utiliza un mayor porcentaje de los azúcares fermentables disponibles, aproximadamente un 50%. Los productos de degradación, resultado de la presacarificación, pueden afectar al microorganismo y actuar como potenciales inhibidores de la fermentación, por lo que es crítico realizar estudios que determinen estos productos de degradación y los mecanismos para su reducción. Podemos concluir que el sistema utilizado es efectivo para el almacenamiento de la biomasa en forma estable en el mismo

  3. Maitrise de la fermentation alcoolique sous stress éthanolique, thermique et osmotique de la souche Saccharomyces cerevisiae YS-DN1 en vue de la préparation du vinaigre de fruits

    Directory of Open Access Journals (Sweden)

    Majid MOUNIR

    2016-07-01

    Full Text Available The purpose of the present study is to isolate, identify and characterize new yeast species of industrial interest. A total of 54 strains were isolated and identified from agricultural raw products and from by-products of the food industry. Among these, four strains were selected, purified and tested for their ability to perform efficient fermentation on Bouslikhène date juice. After the sequencing of the 18S gene of the ribosomal DNA, the two strains YS-DN1 and YS-M isolated respectively from dates and molasses have been identified belonging to Saccharomyces cerevisiae species. In addition, the other two strains, YS-OMP and YS-G isolated from olives and grapes belonged to Kluyveromyces marxianus (78% homology and Candida utilis (89% homology species, respectively. In addition, YS-DN1 strain showed the highest performance in terms of ethanol production in comparison with two other industrial reference strains. YS-DN1 strain was the only one that was able to grow at a temperature ranged from 35 to 40°C in the presence of a high alcoholic concentration and aggressive osmotic pressure condition. Finally, production of the cellular biomass of YS-DN1 strain was improved by optimization of temperature, Brix and pH fixed respectively at 29.75°C, 15.7% and 4.15. These values allowed to obtain a maximum of cells of about 8.4x10 8 UFC/ml. It was concluded that this strain is well suited for fruit vinegar production at a large-scale.

  4. Sustainable conversion of coffee and other crop wastes to biofuels and bioproducts using coupled biochemical and thermochemical processes in a multi-stage biorefinery concept.

    Science.gov (United States)

    Hughes, Stephen R; López-Núñez, Juan Carlos; Jones, Marjorie A; Moser, Bryan R; Cox, Elby J; Lindquist, Mitch; Galindo-Leva, Luz Angela; Riaño-Herrera, Néstor M; Rodriguez-Valencia, Nelson; Gast, Fernando; Cedeño, David L; Tasaki, Ken; Brown, Robert C; Darzins, Al; Brunner, Lane

    2014-10-01

    The environmental impact of agricultural waste from the processing of food and feed crops is an increasing concern worldwide. Concerted efforts are underway to develop sustainable practices for the disposal of residues from the processing of such crops as coffee, sugarcane, or corn. Coffee is crucial to the economies of many countries because its cultivation, processing, trading, and marketing provide employment for millions of people. In coffee-producing countries, improved technology for treatment of the significant amounts of coffee waste is critical to prevent ecological damage. This mini-review discusses a multi-stage biorefinery concept with the potential to convert waste produced at crop processing operations, such as coffee pulping stations, to valuable biofuels and bioproducts using biochemical and thermochemical conversion technologies. The initial bioconversion stage uses a mutant Kluyveromyces marxianus yeast strain to produce bioethanol from sugars. The resulting sugar-depleted solids (mostly protein) can be used in a second stage by the oleaginous yeast Yarrowia lipolytica to produce bio-based ammonia for fertilizer and are further degraded by Y. lipolytica proteases to peptides and free amino acids for animal feed. The lignocellulosic fraction can be ground and treated to release sugars for fermentation in a third stage by a recombinant cellulosic Saccharomyces cerevisiae, which can also be engineered to express valuable peptide products. The residual protein and lignin solids can be jet cooked and passed to a fourth-stage fermenter where Rhodotorula glutinis converts methane into isoprenoid intermediates. The residues can be combined and transferred into pyrocracking and hydroformylation reactions to convert ammonia, protein, isoprenes, lignins, and oils into renewable gas. Any remaining waste can be thermoconverted to biochar as a humus soil enhancer. The integration of multiple technologies for treatment of coffee waste has the potential to

  5. A functional food: a traditional Tarhana fermentation

    Directory of Open Access Journals (Sweden)

    Merih KIVANÇ

    Full Text Available Abstract White wheat flour, concentrated full fat yoghurt, tomato paste, onion, red and green paprika, and mint and salt are used in the preparation of Tarhana. During the 7-day Tarhana fermentation period, the acidity increased from 1.10% to 3.25%, the pH decreased from 5.22 to 4.13, and the moisture decreased from 70.12% to 26.15%. The chemical composition of the Tarhana at the end of fermentation was determined as: moisture 9.55%, protein 12.05%, total ash 5.65%, salt 5.65%, and fat 4.88%. During the fermentation, the lactic acid bacteria count of increased from 1.32 X 102 to 4.20 X 104 CFU/g, the total mesophilic aerobe bacteria count increased from 1.75 X 101 to 2.28 X 102 CFU/g, the yeast count increased from 3.45 X 10 1 to 2.40 X 105 CFU/g, the mould count from 1.55 X 10 1 to 2.45 X 104 CFU/g, in the content of Tarhana dough. It was observed that Lactococcus lactis spp. lactis, Leuconostoc mesenteroides, Lactobacillus acidophilus, Enterococcus durans, Pediococcus spp., Lactobacillus delbrueckii ssp. lactis and Lactobacillus paracasei bacteria played a role during the fermentation of Tarhana dough. Kluyveromyces marxianus, Yarrowia lipolytica, Pichia membranaefaciens, Pichia mexicana, Pichia angusta, Debaryomyces hansenii, Candida sorboxylosa, Candida fluviatilis, Saccharomyces cerevisiae were identified during the Tarhana fermentation.

  6. Enhanced exo-inulinase activity and stability by fusion of an inulin-binding module.

    Science.gov (United States)

    Zhou, Shun-Hua; Liu, Yuan; Zhao, Yu-Juan; Chi, Zhe; Chi, Zhen-Ming; Liu, Guang-Lei

    2016-09-01

    In this study, an inulin-binding module from Bacillus macerans was successfully fused to an exo-inulinase from Kluyveromyces marxianus, creating a hybrid functional enzyme. The recombinant exo-inulinase (rINU), the hybrid enzyme (rINUIBM), and the recombinant inulin-binding module (rIBM) were, respectively, heterologously expressed and biochemically characterized. It was found that both the inulinase activity and the catalytic efficiency (k cat/K m(app)) of the rINUIBM were considerably higher than those of rINU. Though the rINU and the rINUIBM shared the same optimum pH of 4.5, the optimum temperature of the rINUIBM (60 °C) was 5 °C higher than that of the rINU. Notably, the fused IBM significantly enhanced both the pH stability and the thermostability of the rINUIBM, suggesting that the rINUIBM obtained would have more extensive potential applications. Furthermore, the fusion of the IBM could substantially improve the inulin-binding capability of the rINUIBM, which was consistent with the determination of the K m(app). This meant that the fused IBM could play a critical role in the recognition of polysaccharides and enhanced the hydrolase activity of the associated inulinase by increasing enzyme-substrate proximity. Besides, the extra supplement of the independent non-catalytic rIBM could also improve the inulinase activity of the rINU. However, this improvement was much better in case of the fusion. Consequently, the IBM could be designated as a multifunctional domain that was responsible for the activity enhancement, the stabilization, and the substrate binding of the rINUIBM. All these features obtained in this study make the rINUIBM become an attractive candidate for an efficient inulin hydrolysis.

  7. The effect of lactic acid bacteria on cocoa bean fermentation.

    Science.gov (United States)

    Ho, Van Thi Thuy; Zhao, Jian; Fleet, Graham

    2015-07-16

    Cocoa beans (Theobroma cacao L.) are the raw material for chocolate production. Fermentation of cocoa pulp by microorganisms is crucial for developing chocolate flavor precursors. Yeasts conduct an alcoholic fermentation within the bean pulp that is essential for the production of good quality beans, giving typical chocolate characters. However, the roles of bacteria such as lactic acid bacteria and acetic acid bacteria in contributing to the quality of cocoa bean and chocolate are not fully understood. Using controlled laboratory fermentations, this study investigated the contribution of lactic acid bacteria to cocoa bean fermentation. Cocoa beans were fermented under conditions where the growth of lactic acid bacteria was restricted by the use of nisin and lysozyme. The resultant microbial ecology, chemistry and chocolate quality of beans from these fermentations were compared with those of indigenous (control) fermentations. The yeasts Hanseniaspora guilliermondii, Pichia kudriavzevii, Kluyveromyces marxianus and Saccharomyces cerevisiae, the lactic acid bacteria Lactobacillus plantarum, Lactobacillus pentosus and Lactobacillus fermentum and the acetic acid bacteria Acetobacter pasteurianus and Gluconobacter frateurii were the major species found in control fermentations. In fermentations with the presence of nisin and lysozyme, the same species of yeasts and acetic acid bacteria grew but the growth of lactic acid bacteria was prevented or restricted. These beans underwent characteristic alcoholic fermentation where the utilization of sugars and the production of ethanol, organic acids and volatile compounds in the bean pulp and nibs were similar for beans fermented in the presence of lactic acid bacteria. Lactic acid was produced during both fermentations but more so when lactic acid bacteria grew. Beans fermented in the presence or absence of lactic acid bacteria were fully fermented, had similar shell weights and gave acceptable chocolates with no differences

  8. Yeasts are essential for cocoa bean fermentation.

    Science.gov (United States)

    Ho, Van Thi Thuy; Zhao, Jian; Fleet, Graham

    2014-03-17

    Cocoa beans (Theobroma cacao) are the major raw material for chocolate production and fermentation of the beans is essential for the development of chocolate flavor precursors. In this study, a novel approach was used to determine the role of yeasts in cocoa fermentation and their contribution to chocolate quality. Cocoa bean fermentations were conducted with the addition of 200ppm Natamycin to inhibit the growth of yeasts, and the resultant microbial ecology and metabolism, bean chemistry and chocolate quality were compared with those of normal (control) fermentations. The yeasts Hanseniaspora guilliermondii, Pichia kudriavzevii and Kluyveromyces marxianus, the lactic acid bacteria Lactobacillus plantarum and Lactobacillus fermentum and the acetic acid bacteria Acetobacter pasteurianus and Gluconobacter frateurii were the major species found in the control fermentation. In fermentations with the presence of Natamycin, the same bacterial species grew but yeast growth was inhibited. Physical and chemical analyses showed that beans fermented without yeasts had increased shell content, lower production of ethanol, higher alcohols and esters throughout fermentation and lesser presence of pyrazines in the roasted product. Quality tests revealed that beans fermented without yeasts were purplish-violet in color and not fully brown, and chocolate prepared from these beans tasted more acid and lacked characteristic chocolate flavor. Beans fermented with yeast growth were fully brown in color and gave chocolate with typical characters which were clearly preferred by sensory panels. Our findings demonstrate that yeast growth and activity were essential for cocoa bean fermentation and the development of chocolate characteristics. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

  9. Candida utilis and Chlorella vulgaris counteract intestinal inflammation in Atlantic salmon (Salmo salar L..

    Directory of Open Access Journals (Sweden)

    Fabian Grammes

    Full Text Available Intestinal inflammation, caused by impaired intestinal homeostasis, is a serious condition in both animals and humans. The use of conventional extracted soybean meal (SBM in diets for Atlantic salmon and several other fish species is known to induce enteropathy in the distal intestine, a condition often referred to as SBM induced enteropathy (SBMIE. In the present study, we investigated the potential of different microbial ingredients to alleviate SBMIE in Atlantic salmon, as a model of feed-induced inflammation. The dietary treatments consisted of a negative control based on fish meal (FM, a positive control based on 20% SBM, and four experimental diets combining 20% SBM with either one of the three yeasts Candida utilis (CU, Kluyveromyces marxianus (KM, Saccharomyces cerevisiae (SC or the microalgae Chlorella vulgaris (CV. Histopathological examination of the distal intestine showed that all fish fed the SC or SBM diets developed characteristic signs of SBMIE, while those fed the FM, CV or CU diets showed a healthy intestine. Fish fed the KM diet showed intermediate signs of SBMIE. Corroborating results were obtained when measuring the relative length of PCNA positive cells in the crypts of the distal intestine. Gene set enrichment analysis revealed decreased expression of amino acid, fat and drug metabolism pathways as well as increased expression of the pathways for NOD-like receptor signalling and chemokine signalling in both the SC and SBM groups while CV and CU were similar to FM and KM was intermediate. Gene expression of antimicrobial peptides was reduced in the groups showing SBMIE. The characterisation of microbial communities using PCR-DGGE showed a relative increased abundance of Firmicutes bacteria in fish fed the SC or SBM diets. Overall, our results show that both CU and CV were highly effective to counteract SBMIE, while KM had less effect and SC had no functional effects.

  10. Sustainable utilization of ressources. Production of ethanol from dairy waste streams; Nachhaltige Verwertung von Wertstoffstroemen. Gewinnung von Ethanol aus einem Reststoff der Molkeverarbeitung

    Energy Technology Data Exchange (ETDEWEB)

    Benecke, Christian

    2011-07-01

    The worldwide increasing demand for cheese and dairy products leads to a steady increase of whey production. Today, whey is no more considered as waste, but serves as source for materials like lactose and proteins. At the end of this process a whey concentrate is released, which contains still a significant content of lactose. This lactose could not be obtained in the desired quality. This thesis describes a method to increase added value from the utilization-process of whey. To achieve this intent, methods where evaluated, to use the remaining lactose as a substrate for the fermentation to ethanol. Yeasts of the strain Kluyveromyces marxianus were evaluated for the use in this process. The degradation rate of the substrate and a maximized conversion were the main objectives. For the growth of the yeast cells, a method was developed, which uses only whey concentrate as substrate and avoids the usage of other materials for nutrition. The method was optimized in consideration of initial substrate concentration and degradation rate. The high content of salts in the whey concentrate leads to the further investigations of inhabitating or proliferating effects of different anions and cations on the used yeast cells. It becomes obvious, that a desalting or dilution of the used whey concentrate is mandatory. For that purpose, the nanofiltration was applied successfully to this process. The usage of not desalted whey concentrate is also possible. With an adequate dilution of the whey concentrate, relative yields of ca. 90% could be achieved. With a significant increase of the initial biomass, the duration of the fermentation process could be halved to ca. 25 h. (orig.)

  11. Electron transport chain in a thermotolerant yeast.

    Science.gov (United States)

    Mejía-Barajas, Jorge A; Martínez-Mora, José A; Salgado-Garciglia, Rafael; Noriega-Cisneros, Ruth; Ortiz-Avila, Omar; Cortés-Rojo, Christian; Saavedra-Molina, Alfredo

    2017-04-01

    Yeasts capable of growing and surviving at high temperatures are regarded as thermotolerant. For appropriate functioning of cellular processes and cell survival, the maintenance of an optimal redox state is critical of reducing and oxidizing species. We studied mitochondrial functions of the thermotolerant Kluyveromyces marxianus SLP1 and the mesophilic OFF1 yeasts, through the evaluation of its mitochondrial membrane potential (ΔΨ m ), ATPase activity, electron transport chain (ETC) activities, alternative oxidase activity, lipid peroxidation. Mitochondrial membrane potential and the cytoplasmic free Ca 2+ ions (Ca 2+ cyt) increased in the SLP1 yeast when exposed to high temperature, compared with the mesophilic yeast OFF1. ATPase activity in the mesophilic yeast diminished 80% when exposed to 40° while the thermotolerant SLP1 showed no change, despite an increase in the mitochondrial lipid peroxidation. The SLP1 thermotolerant yeast exposed to high temperature showed a diminution of 33% of the oxygen consumption in state 4. The uncoupled state 3 of oxygen consumption did not change in the mesophilic yeast when it had an increase of temperature, whereas in the thermotolerant SLP1 yeast resulted in an increase of 2.5 times when yeast were grown at 30 o , while a decrease of 51% was observed when it was exposed to high temperature. The activities of the ETC complexes were diminished in the SLP1 when exposed to high temperature, but also it was distinguished an alternative oxidase activity. Our results suggest that the mitochondria state, particularly ETC state, is an important characteristic of the thermotolerance of the SLP1 yeast strain.

  12. Thermotolerant and mesophylic fungi from sugarcane bagasse and their prospection for biomass-degrading enzyme production

    Directory of Open Access Journals (Sweden)

    Bruna Silveira Lamanes dos Santos

    2015-09-01

    Full Text Available Nineteen fungi and seven yeast strains were isolated from sugarcane bagasse piles from an alcohol plant located at Brazilian Cerrado and identified up to species level on the basis of the gene sequencing of 5.8S-ITS and 26S ribosomal DNA regions. Four species were identified: Kluyveromyces marxianus, Aspergillus niger, Aspergillus sydowii and Aspergillus fumigatus, and the isolates were screened for the production of key enzymes in the saccharification of lignocellulosic material. Among them, three strains were selected as good producers of hemicellulolitic enzymes: A. niger (SBCM3, A. sydowii (SBCM7 and A. fumigatus (SBC4. The best β-xylosidase producer was A. niger SBCM3 strain. This crude enzyme presented optimal activity at pH 3.5 and 55 °C (141 U/g. For β-glucosidase and xylanase the best producer was A. fumigatus SBC4 strain, whose enzymes presented maximum activity at 60 °C and pH 3.5 (54 U/g and 4.0 (573 U/g, respectively. All these crude enzymes presented stability around pH 3.0–8.0 and up to 60 °C, which can be very useful in industrial processes that work at high temperatures and low pHs. These enzymes also exhibited moderate tolerance to ethanol and the sugars glucose and xylose. These similar characteristics among these fungal crude enzymes suggest that they can be used synergistically in cocktails in future studies of biomass conversion with potential application in several biotechnological sectors.

  13. Manufacture of a beverage from cheese whey using a "tea fungus" fermentation.

    Science.gov (United States)

    Belloso-Morales, Genette; Hernández-Sánchez, Humberto

    2003-01-01

    Kombucha is a sour beverage reported to have potential health effects prepared from the fermentation of black tea and sugar with a "tea fungus", a symbiotic culture of acetic acid bacteria and yeasts. Although black tea is the preferred substrate for Kombucha fermentation, other beverages have also been tested as substrates with fair results. Cheese whey is a by-product with a good amount of fermentable lactose that has been used before in the production of beverages, so the objective of this study was to test three types of whey (fresh sweet, fresh acid and reconstituted sweet) in the elaboration of a fermented beverage using a kombucha culture as inoculum. The isolation and identification of bacteria and yeasts from the fermented tea and wheys was done along with the study of the rates of change in sugar consumption, acid production and pH decrease. Several species of acetic acid bacteria (Acetobacter aceti subsp. aceti, Gluconobacter oxydans subsp. industrius, subsp. oxydans and Gluconoacetobacter xylinus) were isolated from the different kombuchas along with the yeasts Saccharomyces cerevisiae, Kluyveromyces marxianus, and Brettanomyces bruxelensis. The main metabolic products in the fermented wheys included ethanol, lactic and acetic acids. A good growth was obtained in both sweet wheys in which a pH of 3.3 and a total acid content (mainly lactic and acetic acids) of 0.07 mol/l was reached after 96 h. The sweet whey fermented beverages contained a relatively low lactose concentration (< 12 g/l). The final ethanol content was low (5 g/l) in all the fermented wheys. The whey products were strongly sour and salty non sparkling beverages.

  14. Proteoma extracelular de Kluyveromyces lactis em cultura contínua sob limitação de nitrogênio

    OpenAIRE

    Santos, Agenor Valadares

    2008-01-01

    A identificação de proteínas extracelulares de leveduras em cultura contínua pode oferecer informações sobre a influência do status nutricional na via de captura de nutrientes alternativos. Essa análise auxilia a otimização das condições necessárias para a produção dessas proteínas com o máximo rendimento, além de oferecer uma estratégia de construção de um sistema de expressão e secreção de proteínas em leveduras. Neste trabalho, mostra-se o perfil das proteínas extracelulares de culturas de...

  15. Temperature and relative humidity influence the microbial and physicochemical characteristics of Camembert-type cheese ripening.

    Science.gov (United States)

    Leclercq-Perlat, M-N; Sicard, M; Trelea, I C; Picque, D; Corrieu, G

    2012-08-01

    To evaluate the effects of temperature and relative humidity (RH) on microbial and biochemical ripening kinetics, Camembert-type cheeses were prepared from pasteurized milk seeded with Kluyveromyces marxianus, Geotrichum candidum, Penicillium camemberti, and Brevibacterium aurantiacum. Microorganism growth and biochemical changes were studied under different ripening temperatures (8, 12, and 16°C) and RH (88, 92, and 98%). The central point runs (12°C, 92% RH) were both reproducible and repeatable, and for each microbial and biochemical parameter, 2 kinetic descriptors were defined. Temperature had significant effects on the growth of both K. marxianus and G. candidum, whereas RH did not affect it. Regardless of the temperature, at 98% RH the specific growth rate of P. camemberti spores was significantly higher [between 2 (8°C) and 106 times (16°C) higher]. However, at 16°C, the appearance of the rind was no longer suitable because mycelia were damaged. Brevibacterium aurantiacum growth depended on both temperature and RH. At 8°C under 88% RH, its growth was restricted (1.3 × 10(7) cfu/g), whereas at 16°C and 98% RH, its growth was favored, reaching 7.9 × 10(9) cfu/g, but the rind had a dark brown color after d 20. Temperature had a significant effect on carbon substrate consumption rates in the core as well as in the rind. In the rind, when temperature was 16°C rather than 8°C, the lactate consumption rate was approximately 2.9 times higher under 88% RH. Whatever the RH, temperature significantly affected the increase in rind pH (from 4.6 to 7.7 ± 0.2). At 8°C, an increase in rind pH was observed between d 6 and 9, whereas at 16°C, it was between d 2 and 3. Temperature and RH affected the increasing rate of the underrind thickness: at 16°C, half of the cheese thickness appeared ripened on d 14 (wrapping day). However, at 98% RH, the underrind was runny. In conclusion, some descriptors, such as yeast growth and the pH in the rind, depended solely on

  16. Short communication: Evaluation of the microbiota of kefir samples using metagenetic analysis targeting the 16S and 26S ribosomal DNA fragments.

    Science.gov (United States)

    Korsak, N; Taminiau, B; Leclercq, M; Nezer, C; Crevecoeur, S; Ferauche, C; Detry, E; Delcenserie, V; Daube, G

    2015-06-01

    in sample D. In relation to 26S pyrosequencing, our study revealed the presence of 3 main yeast species: Naumovozyma spp., Kluyveromyces marxianus, and Kazachastania khefir. For Naumovozyma, further studies are needed to assess the isolation of new species. In conclusion, this study has proved that it is possible to establish the patterns of bacterial and yeast composition of kefir and kefir grain. This was only achieved with the use of high-throughput sequencing techniques. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  17. Kefir-isolated bacteria and yeasts inhibit Shigella flexneri invasion and modulate pro-inflammatory response on intestinal epithelial cells.

    Science.gov (United States)

    Bolla, P A; Abraham, A G; Pérez, P F; de Los Angeles Serradell, M

    2016-02-01

    The aim of this work was to evaluate the ability of a kefir-isolated microbial mixture containing three bacterial and two yeast strains (MM) to protect intestinal epithelial cells against Shigella flexneri invasion, as well as to analyse the effect on pro-inflammatory response elicited by this pathogen. A significant decrease in S. flexneri strain 72 invasion was observed on both HT-29 and Caco-2 cells pre-incubated with MM. Pre-incubation with the individual strains Saccharomyces cerevisiae CIDCA 8112 or Lactococcus lactis subsp. lactis CIDCA 8221 also reduced the internalisation of S. flexneri into HT-29 cells although in a lesser extent than MM. Interestingly, Lactobacillus plantarum CIDCA 83114 exerted a protective effect on the invasion of Caco-2 and HT-29 cells by S. flexneri. Regarding the pro-inflammatory response on HT-29 cells, S. flexneri infection induced a significant activation of the expression of interleukin 8 (IL-8), chemokine (C-C motif) ligand 20 (CCL20) and tumour necrosis factor alpha (TNF-α) encoding genes (P<0.05), whereas incubation of cells with MM did not induce the expression of any of the mediators assessed. Interestingly, pre-incubation of HT-29 monolayer with MM produced an inhibition of S. flexneri-induced IL-8, CCL20 and TNF-α mRNA expression. In order to gain insight on the effect of MM (or the individual strains) on this pro-inflammatory response, a series of experiments using a HT-29-NF-κB-hrGFP reporter system were performed. Pre-incubation of HT-29-NF-κB-hrGFP cells with MM significantly dampened Shigella-induced activation. Our results showed that the contribution of yeast strain Kluyveromyces marxianus CIDCA 8154 seems to be crucial in the observed effect. In conclusion, results presented in this study demonstrate that pre-treatment with a microbial mixture containing bacteria and yeasts isolated from kefir, resulted in inhibition of S. flexneri internalisation into human intestinal epithelial cells, along with the

  18. Identification of uncommon oral yeasts from cancer patients by MALDI-TOF mass spectrometry.

    Science.gov (United States)

    Aslani, Narges; Janbabaei, Ghasem; Abastabar, Mahdi; Meis, Jacques F; Babaeian, Mahasti; Khodavaisy, Sadegh; Boekhout, Teun; Badali, Hamid

    2018-01-08

    Opportunistic infections due to Candida species occur frequently in cancer patients because of their inherent immunosuppression. The aim of the present study was to investigate the epidemiology of yeast species from the oral cavity of patients during treatment for oncological and haematological malignancies. MALDI-TOF was performed to identify yeasts isolated from the oral cavity of 350 cancer patients. Moreover, antifungal susceptibility testing was performed in according to CLSI guidelines (M27-A3). Among 162 yeasts and yeast-like fungi isolated from the oral cavity of cancer patients, Candida albicans was the most common species (50.6%), followed by Candida glabrata (24.7%), Pichia kudriavzevii (Candida krusei (9.9%)), Candida tropicalis (4.3%), Candida dubliniensis (3.7%), Kluyveromyces marxianus (Candida kefyr (3.7%)) and Candida parapsilosis (1%). In addition, uncommon yeast species i.e., Saprochaete capitata, Saccharomyces cerevisiae, Clavispora lusitaniae (C. lusitaniae) and Pichia kluyveri (C. eremophila) were recovered from oral lesions. Oral colonization by C. albicans, non-albicans Candida species and uncommon yeasts were as follow; 55%, 44% and 1%, whereas oral infection due to C. albicans was 33.3%, non-albicans Candida species 60.6%, and uncommon yeasts 6.1%. Poor oral hygiene and xerostomia were identified as independent risk factors associated with oral yeast colonization. The overall resistance to fluconazole was 11.7% (19/162). Low MIC values were observed for anidulafungin for all Candida and uncommon yeast species. This current study provides insight into the prevalence and susceptibility profiles of Candida species, including emerging Candida species and uncommon yeasts, isolated from the oral cavity of Iranian cancer patients. The incidence of oral candidiasis was higher amongst patients with hematological malignancies. The majority of oral infections were caused by non-albicans Candida species which were often more resistant to anti

  19. Microbial and chemical transformation studies of the bioactive marine sesquiterpenes (S)-(+)-curcuphenol and -curcudiol isolated from a deep reef collection of the Jamaican sponge Didiscus oxeata.

    Science.gov (United States)

    El Sayed, Khalid A; Yousaf, Muhammad; Hamann, Mark T; Avery, Mitchell A; Kelly, Michelle; Wipf, Peter

    2002-11-01

    Microbial and chemical transformation studies of the marine sesquiterpene phenols (S)-(+)-curcuphenol (1) and (S)-(+)-curcudiol (2), isolated from the Jamaican sponge Didiscus oxeata, were accomplished. Preparative-scale fermentation of 1 with Kluyveromyces marxianus var. lactis (ATCC 2628) has resulted in the isolation of six new metabolites: (S)-(+)-15-hydroxycurcuphenol (3), (S)-(+)-12-hydroxycurcuphenol (4), (S)-(+)-12,15-dihydroxycurcuphenol (5), (S)-(+)-15-hydroxycurcuphenol-12-al (6), (S)-(+)-12-carboxy-10,11-dihydrocurcuphenol (7), and (S)-(+)-12-hydroxy-10,11-dihydrocurcuphenol (8). Fourteen-days incubation of 1 with Aspergillus alliaceus (NRRL 315) afforded the new compounds (S)-(+)-10beta-hydroxycurcudiol (9), (S)-(+)-curcudiol-10-one (10), and (S)-(+)-4-[1-(2-hydroxy-4-methyl)phenyl)]pentanoic acid (11). Rhizopus arrhizus (ATCC 11145) and Rhodotorula glutinus (ATCC 15125) afforded (S)-curcuphenol-1alpha-D-glucopyranoside (12) and (S)-curcudiol-1alpha-D-glucopyranoside (13) when incubated for 6 and 8 days with 1 and 2, respectively. The absolute configuration of C(10) and C(11) of metabolites 7-9 was established by optical rotation computations. Reaction of 1 with NaNO(2) and HCl afforded (S)-(+)-4-nitrocurcuphenol (14) and (S)-(+)-2-nitrocurcuphenol (15) in a 2:1 ratio. Acylation of 1 and 2 with isonicotinoyl chloride afforded the expected esters (S)-(+)-curcuphenol-1-O-isonicotinate (16) and (S)-(+)-curcudiol-1-O-isonicotinate (17), respectively. Curcuphenol (1) shows potent antimicrobial activity against Candida albicans, Cryptococcus neoformans, methicillin-resistant Staphylococcus aureus, and S. aureus with MIC and MFC/MBC ranges of 7.5-25 and 12.5-50 microg/mL, respectively. Compounds 1 and 3 also display in vitro antimalarial activity against Palsmodium falciparium (D6 clone) with MIC values of 3600 and 3800 ng/mL, respectively (selectivity index >1.3). Both compounds were also active against P. falciparium (W2 clone) with MIC values of 1800 (S

  20. Yeasts associated with fresh and frozen pulps of Brazilian tropical fruits.

    Science.gov (United States)

    Trindade, Rita C; Resende, Maria Aparecida; Silva, Claudia M; Rosa, Carlos A

    2002-08-01

    The occurrence of yeasts on ripe fruits and frozen pulps of pitanga (Eugenia uniflora L), mangaba (Hancornia speciosa Gom.), umbu (Spondias tuberosa Avr. Cam.), and acerola (Malpighia glaba L) was verified. The incidence of proteolytic, pectinolytic, and mycocinogenic yeasts on these communities was also determined. A total of 480 colonies was isolated and grouped in 405 different strains. These corresponded to 42 ascomycetous and 28 basidiomycetous species. Candida sorbosivorans, Pseudozyma antarctica, C. spandovensis-like, C. spandovensis, Kloeckera apis, C. parapsilosis, Rhodotorula graminis, Kluyveromyces marxianus, Cryptococcus laurentii, Metchnikowia sp (isolated only from pitanga ripe fruits), Issatchenkia occidentalis and C. krusei (isolated only from mangaba frozen pulps), were the most frequent species. The yeast communities from pitanga ripe fruits exhibited the highest frequency of species, followed by communities from acerola ripe fruits and mangaba frozen pulps. Yeast communities from frozen pulp and ripe fruits of umbu had the lowest number of species. Except the yeasts from pitanga, yeast communities from frozen pulp exhibited higher number of yeasts than ripe fruit communities. Mycocinogenic yeasts were found in all of the substrates studied except in communities from umbu ripe fruits and pitanga frozen pulps. Most of the yeasts found to produce mycocins were basidiomycetes and included P. antarctica, Cryptococcus albidus, C. bhutanensis-like, R. graminis and R. mucilaginosa-like from pitanga ripe fruits as well as black yeasts from pitanga and acerola ripe fruits. The umbu frozen pulps community had the highest frequency of proteolytic species. Yeasts able to hydrolyse casein at pH 5.0 represented 38.5% of the species isolated. Thirty-seven percent of yeast isolates were able to hydrolyse casein at pH 7.0. Pectinolytic yeasts were found in all of the communities studied, excepted for those of umbu frozen pulps. The highest frequency of

  1. Construction of lactose-consuming Saccharomyces cerevisiae for lactose fermentation into ethanol fuel.

    Science.gov (United States)

    Zou, Jing; Guo, Xuewu; Shen, Tong; Dong, Jian; Zhang, Cuiying; Xiao, Dongguang

    2013-04-01

    Two lactose-consuming diploid Saccharomyces cerevisiae strains, AY-51024A and AY-51024M, were constructed by expressing the LAC4 and LAC12 genes of Kluyveromyces marxianus in the host strain AY-5. In AY-51024A, both genes were targeted to the ATH1 and NTH1 gene-encoding regions to abolish the activity of acid/neutral trehalase. In AY-51024M, both genes were respectively integrated into the MIG1 and NTH1 gene-encoding regions to relieve glucose repression. Physiologic studies of the two transformants under anaerobic cultivations in glucose and galactose media indicated that the expression of both LAC genes did not physiologically burden the cells, except for AY-51024A in glucose medium. Galactose consumption was initiated at higher glucose concentrations in the MIG1 deletion strain AY-51024M than in the corresponding wild-type strain and AY-51024A, wherein galactose was consumed until glucose was completely depleted in the mixture. In lactose medium, the Sp. growth rates of AY-51024A and AY-51024M under anaerobic shake-flasks were 0.025 and 0.067 h(-1), respectively. The specific lactose uptake rate and ethanol production of AY-51024M were 2.50 g lactose g CDW(-1) h(-1) and 23.4 g l(-1), respectively, whereas those of AY-51024A were 0.98 g lactose g CDW(-1) h(-1) and 24.3 g lactose g CDW(-1) h(-1), respectively. In concentrated cheese whey powder solutions, AY-51024M produced 63.3 g l(-1) ethanol from approximately 150 g l(-1) initial lactose in 120 h, conversely, AY-51024A consumed 63.7 % of the initial lactose and produced 35.9 g l(-1) ethanol. Therefore, relieving glucose repression is an effective strategy for constructing lactose-consuming S. cerevisiae.

  2. EXTRACCIÓN Y CUANTIFICACIÓN DE LOS POLÍSACARIDOS DE LA PARED CELULAR DE LAS LEVADURAS

    Directory of Open Access Journals (Sweden)

    Elba M. Alcázar V

    2016-01-01

    Full Text Available Los polisacáridos de la pared celular de las levaduras, se dividen en: 1,3 B - gluc anos, 1,6 B - glucanos, manoproteínas y quitina. Estos componentes representan una fuente potencial de aplicaciones en la industria alimentaria y farmacéutica. Por lo tanto, p ara su extracción existen d iferentes protocolos, en donde para lograr la separación de los componentes de la pared se basan en su solubilidad en soluciones alcalinas y/o e n ácidos inorgánicos, que posteriormente son hidrolizados y usualmente cuantificado por técnicas espectrofotométricas con reactivos de fenol - ácido sulfúrico y/o con el reactivo de antrona . Algunas metodologías sólo extraen los componentes celulares en una fracción total, limitando su cuantificación y análisis para el desarrollo de nuevas aplicaciones en las industrias alimentaría y farmacéutica, mientras que otros método s dividen a la pared celular en sus tres componentes. No obstante, para su cuantificación y análisis utilizan metodologías extensas y complicadas . El objetivo del presente traba jo fue proponer un a metodología de extracción de la pared celular de dos cepas de levadura ( Saccharomyces cerevisiae y Kluyveromyces marxianus a través de una extracción alcalina , dividiendo en tres fracciones los componentes de la pared celular para su posterior cuantifica ción a partir de cromatografía de líquidos. Se encontró que las cepas de levadura empleadas presentan diferencias estadísticas significativas en la concentración de 1,3 B - glucanos, y que los rendimientos obtenidos en la extracción de la pared celular de am bas cepas de levadura son similares a los reportados en estudios previos. Por lo tanto, podemos concluir que la extracción de la pared celular empleando esta metodología es confiable.

  3. Diversidad de levaduras asociadas a chichas tradicionales de Colombia

    Directory of Open Access Journals (Sweden)

    William Andrés López-Arboleda

    2010-07-01

    Full Text Available Título en inglés: Yeast diversity associated to Colombian traditional “chichas” Resumen En Colombia el conocimiento de la comunidad levaduriforme ha sido limitado, ya que los estudios se han enfocado principalmente en especies de interés clínico. Las fermentaciones espontáneas a partir de diversos sustratos representan hábitats de gran importancia para el estudio de la dinámica de las poblaciones de levaduras nativas, por esta razón, en el presente estudio se aislaron e identificaron las levaduras asociadas a las chichas de maíz, piña y arracacha, que son bebidas fermentadas de manera artesanal en Colombia. Se realizó el aislamiento de las levaduras más representativas de la chicha durante sus tres fases de fermentación: inicial, tumultuosa y final. Inicialmente, se hizo una caracterización parcial de los aislados, que incluyó pruebas fisiológicas, y medición de su capacidad para producir filamentos y esporas. Sin embargo, debido a que estas técnicas no fueron suficientes para identificar los aislados hasta el nivel taxonómico de género o de especie, se complementó el estudio de cada aislado empleando técnicas moleculares basadas en el análisis de restricción del gen rRNA 5.8S y los espaciadores transcritos internos (ITS1 e ITS2. Cuando el empleo de esta técnica no permitió obtener resultados definitivos y para confirmar las asignaciones realizadas usando PCR-RFLPs, se secuenció el dominio D1/D2 del gen 26S rRNA de los aislados más representativos. Mediante estas técnicas se lograron identificar las especies más representativas de los tres tipos de chicha: Candida tropicalis, Pichia kluyveri, Pichia guilliermondii, Hanseniapora guilliermondii, Pichia fermentans, Saccharomyces cerevisiae, Candida maltosa, Rhodotorula glutinis, Torulaspora delbrueckii, Hanseniaspora uvarum, Kazachstania exigua, Kluyveromyces marxianus, Yarrowia lypolitica, Candida parapsilosis, Debaromyces hansenii, Cryptococcus arboriformis

  4. Diversidad de levaduras asociadas a chichas tradicionales de Colombia

    Directory of Open Access Journals (Sweden)

    William Andrés López-Arboleda

    2011-01-01

    Full Text Available Título en inglés: Yeast diversity associated to Colombian traditional “chichas” Resumen En Colombia el conocimiento de la comunidad levaduriforme ha sido limitado, ya que los estudios se han enfocado principalmente en especies de interés clínico. Las fermentaciones espontáneas a partir de diversos sustratos representan hábitats de gran importancia para el estudio de la dinámica de las poblaciones de levaduras nativas, por esta razón, en el presente estudio se aislaron e identificaron las levaduras asociadas a las chichas de maíz, piña y arracacha, que son bebidas fermentadas de manera artesanal en Colombia. Se realizó el aislamiento de las levaduras más representativas de la chicha durante sus tres fases de fermentación: inicial, tumultuosa y final. Inicialmente, se hizo una caracterización parcial de los aislados, que incluyó pruebas fisiológicas, y medición de su capacidad para producir filamentos y esporas. Sin embargo, debido a que estas técnicas no fueron suficientes para identificar los aislados hasta el nivel taxonómico de género o de especie, se complementó el estudio de cada aislado empleando técnicas moleculares basadas en el análisis de restricción del gen rRNA 5.8S y los espaciadores transcritos internos (ITS1 e ITS2. Cuando el empleo de esta técnica no permitió obtener resultados definitivos y para confirmar las asignaciones realizadas usando PCR-RFLPs, se secuenció el dominio D1/D2 del gen 26S rRNA de los aislados más representativos. Mediante estas técnicas se lograron identificar las especies más representativas de los tres tipos de chicha: Candida tropicalis, Pichia kluyveri, Pichia guilliermondii, Hanseniapora guilliermondii, Pichia fermentans, Saccharomyces cerevisiae, Candida maltosa, Rhodotorula glutinis, Torulaspora delbrueckii, Hanseniaspora uvarum, Kazachstania exigua, Kluyveromyces marxianus, Yarrowia lypolitica, Candida parapsilosis, Debaromyces hansenii, Cryptococcus arboriformis

  5. Condições fisiológicas que favorecem a síntese de ácido L-ascórbico (vitamina C) por culturas de Kluyveromyces lactis metabolicamente engenheirada

    OpenAIRE

    Alvim, Mariana Caroline Tocantins

    2014-01-01

    O ácido L-ascórbico (ALA) é produzido naturalmente por plantas a partir de D-glicose. Leveduras sintetizam um metabólito semelhante, o ácido D-eritroascórbico (ADEA). Embora este composto não mostre atividade contra o escorbuto, ele contém uma função antioxidante, mas é produzido pelo micro-organismo em baixas concentrações. Recentemente, com a finalidade de fazer as leveduras serem capazes de converter o componente D-galactose da D-lactose do soro de queijo em ALA, a linhagem selvagem de Klu...

  6. [Research in high energy physics

    International Nuclear Information System (INIS)

    LoSecco, J.

    1989-01-01

    We review the efforts of the Notre Dame non accelerator high energy physics group. Our major effort has been directed toward the IMB deep underground detector. Since the departure of the Michigan group our responsibilities to the group have grown. We are also very active in pursuing physics with the IMB 3 detector. Currently we are studying proton decay, point neutrino sources and neutrino oscillations with the contained event sample

  7. Dregs of our forgotten ancestors: fermentative microorganisms in the prehistory of Europe, the steppes and Indo-Iranian Asia, and their contemporary use in traditional and probiotic beverages

    Science.gov (United States)

    Fermentative microorganisms in the yeast genera Debaryomyces, Hyphopichia, Kluyveromyces, Lachancea, Saccharomyces, and Wickerhamomyces (and in the bacterial genus Lactobacillus) have been isolated from a variety of fermented beverages. These same microorganisms were very likely unknowingly utilized...

  8. Alcohol production from whey

    Energy Technology Data Exchange (ETDEWEB)

    Reesen, L

    1978-01-01

    The continuous production of ethanol from whey permeate, by fermentation of its lactose with Kluyveromyces fragilis, is described. From whey containing 4.4% lactose, production costs were very competitive with those for alcohol from molasses.

  9. Installation Restoration Program. Phase 2. Confirmation/Quantification. Stage 1 for Pease Air Force Base, New Hampshire. Volume 2. Appendices.

    Science.gov (United States)

    1987-08-01

    san Agency Judgment on an amn pces that are more sensitive The .vlaldt’a . acca ~ble" siskieavel. . that those tested. Mortality to early life...METHOD -30 c 7P~4- 1]I07- .ps cC4 Zw /5(,ov 12򒵃 /I04dOSIT/ - RIEP PIIS Bi,0614 L 1 111 16" AL F6 t 7 9 2349, -* ,* I- ~CL */1.CIIIT C-CL).1- LI tNT I...LWpCL MAILSE ORIGINALD (.. .I hla REPRT 7e__ _ __ _ __ _ 1" -L 5.um.Iwf TOr4 c0opy 131210421, ( ^i F6 .,Ol+,3uicj.Imb3 COPYS 2L0 _______COLLCTEDB_____

  10. A serach for moderate- and high-energy neturino emission correlated with gamma-ray bursts

    Science.gov (United States)

    Becker-Szendy, R.; Bratton, C. B.; Breault, J.; Casper, D.; Dye, S. T.; Gajewski, W.; Goldhaber, M.; Haines, T. J.; Halverson, P. G.; Kielczewska, D.

    1995-01-01

    A temporal correlation analysis between moderate- (60 Mev less than or equal to E(sub nu)greater than or equal to 2500 MeV) and high-energy (E(sub nu) greater than or equal to 2000 MeV) neutrino interactions consist of two types: the moderate-energy interactions that are contained within the volume of IMB-3 and the upward-going muons produced by high-energy nu(sub mu) interactions in the rock around the detector. No evidence is found for moderate- or high-energy neutrino emission from GRBs nor for any neutrino/neutrino correlation. The nonobservation of nu/GRB correlations allows upper limits to be placed on the neutrino flux associated with GRBs.

  11. Magnetically responsive yeast cells: methods of preparation and applications

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Maděrová, Zdeňka; Pospišková, K.; Horská, Kateřina; Šafaříková, Miroslava

    2015-01-01

    Roč. 32, č. 1 (2015), s. 227-237 ISSN 0749-503X R&D Projects: GA MŠk(CZ) LD13023; GA MŠk(CZ) LD13021 Institutional support: RVO:67179843 Keywords : yeast cells * Saccharomyces * Kluyveromyces * Rhodotorula * Yarrowia * magnetic modification Subject RIV: CE - Biochemistry Impact factor: 2.259, year: 2015

  12. A vertical ball mill as a new reactor design for biomass hydrolysis and fermentation process

    DEFF Research Database (Denmark)

    de Assis Castro, Rafael Cunha; Mussatto, Solange I.; Conceicao Roberto, Inês

    2017-01-01

    A vertical ball mill (VBM) reactor was evaluated for use in biomass conversion processes. The effects of agitation speed (100–200 rpm), number of glass spheres (0–30 units) and temperature (40–46 °C) on enzymatic hydrolysis of rice straw and on glucose fermentation by a thermotolerant Kluyveromyces...

  13. PROTEIN ENRICHMENT OF SPENT SORGHUM RESIDUE USING ...

    African Journals Online (AJOL)

    BSN

    The optimum concentration of spent sorghum for protein enrichment with S. cerevisiae was 7.Sg/100 ml. Th.: protein ... production of single sell protein using Candida utilis and cassava starch effluem as substrate. ... wastes as substrates, Kluyveromyces fragilis and milk whey coconut water as substrate (Rahmat et al.,. 1995 ...

  14. Endo-xylogalacturonan hydrolase

    NARCIS (Netherlands)

    Herweijer, M.A.; Vincken, J.P.; Meeuwsen, P.J.A.; Vlugt-Bergmans, van der C.J.B.; Beldman, G.; Ooyen, van A.J.J.; Voragen, A.G.J.

    2003-01-01

    A cDNA library of Aspergillus tubingensis was constructed in the yeast Kluyveromyces lactis, using a carbon source rich in xylogalacturonan. The library was screened using a hairy regions preparation from apple, and xylogalacturonan prepared from gum tragacanth as substrates. A novel

  15. Effect of diffusion on enzyme activity in a microreactor

    NARCIS (Netherlands)

    Swarts, J.W.; Kolfschoten, R.C.; Jansen, M.C.A.A.; Janssen, A.E.M.; Boom, R.M.

    2010-01-01

    To establish general rules for setting up an enzyme microreactor system, we studied the effect of diffusion on enzyme activity in a microreactor. As a model system we used the hydrolysis of ortho-nitrophenyl-ß-d-galactopyranoside by ß-galactosidase from Kluyveromyces lactis. We found that the

  16. Molecular and biochemical studies of some yeast strains

    African Journals Online (AJOL)

    user

    2011-02-21

    Feb 21, 2011 ... Kluyveromyces lactis (Y.9) and Pichia jadinii (Y.10) contained almost double the amount of total amino ... Differences between ... biochemical analysis (total protein profile and total amino acids) were used as tools to select the best yeast strains in Saudi Arabia and Egypt as a rich source of animal protein.

  17. Selection of yeast strains for the production of alcohol from lactoserum

    Energy Technology Data Exchange (ETDEWEB)

    Laham-Guillaume, M; Moulin, G; Galzy, P

    1979-01-01

    Five of 11 yeast strains tested fermented 85 g lactose/L to approximately 5% EtOH. Four of these strains, Candida pseudotropicalis CBS 19384 and IP 513, and Kluyveromyces fragilis CBS 397, and CBS 5795, anaerobically fermented deproteinized whey to EtOH.

  18. Secretory expression of Rhizopus oryzae α-amylase in ...

    African Journals Online (AJOL)

    Kluyveromyces lactis is a non-conventional yeast species extensively used in the expression of heterologous genes. In this study, a genetically modified K. lactis with high-level expression of α- amylase from Rhizopus oryzae was obtained, which could successfully hydrolyze and use starch for growth very well. Shake flask ...

  19. Ability for anaerobic growth is not sufficient for development of the petite phenotype in Saccharomyces kluyveri

    DEFF Research Database (Denmark)

    Møller, Kasper; Olsson, Lisbeth; Piskur, Jure

    2001-01-01

    Saccharomyces cerevisiae is a petite-phenotype-positive ("petite-positive") yeast, which can successfully grow in the absence of oxygen. On the other hand, Kluyveromyces lactis as well as many other yeasts are petite negative and cannot grow anaerobically. In this paper, we show that Saccharomyces...... kluyveri can grow under anaerobic conditions, but while it can generate respiration-deficient mutants, it cannot generate true petite mutants. From a phylogenetic point of view, S. kluyveri is apparently more closely related to S. cerevisiae than to K. lactis. These observations suggest that the progenitor...... of the modern Saccharomyces and Kluyveromyces yeasts, as well as other related genera, was a petite-negative and aerobic yeast. Upon separation of the K. lactis and S. kluyveri-S. cerevisiae lineages, the latter developed the ability to grow anaerobically. However, while the S. kluyveri lineage has remained...

  20. AcEST: DK953938 [AcEST

    Lifescience Database Archive (English)

    Full Text Available on tr|A3TZ18|A3TZ18_9RHOB ATP-dependent metalloprotease FtsH OS=Oceanicola batsensis HTCC2597 Align length 7...0E06711p OS=Kluyveromyces lactis GN=K... 33 9.8 >tr|A3TZ18|A3TZ18_9RHOB ATP-dependent metalloprotease FtsH OS=Oceanicola bats

  1. Yeast Interspecies Comparative Proteomics Reveals Divergence in Expression Profiles and Provides Insights into Proteome Resource Allocation and Evolutionary Roles of Gene Duplication*

    Science.gov (United States)

    Kito, Keiji; Ito, Haruka; Nohara, Takehiro; Ohnishi, Mihoko; Ishibashi, Yuko; Takeda, Daisuke

    2016-01-01

    Omics analysis is a versatile approach for understanding the conservation and diversity of molecular systems across multiple taxa. In this study, we compared the proteome expression profiles of four yeast species (Saccharomyces cerevisiae, Saccharomyces mikatae, Kluyveromyces waltii, and Kluyveromyces lactis) grown on glucose- or glycerol-containing media. Conserved expression changes across all species were observed only for a small proportion of all proteins differentially expressed between the two growth conditions. Two Kluyveromyces species, both of which exhibited a high growth rate on glycerol, a nonfermentative carbon source, showed distinct species-specific expression profiles. In K. waltii grown on glycerol, proteins involved in the glyoxylate cycle and gluconeogenesis were expressed in high abundance. In K. lactis grown on glycerol, the expression of glycolytic and ethanol metabolic enzymes was unexpectedly low, whereas proteins involved in cytoplasmic translation, including ribosomal proteins and elongation factors, were highly expressed. These marked differences in the types of predominantly expressed proteins suggest that K. lactis optimizes the balance of proteome resource allocation between metabolism and protein synthesis giving priority to cellular growth. In S. cerevisiae, about 450 duplicate gene pairs were retained after whole-genome duplication. Intriguingly, we found that in the case of duplicates with conserved sequences, the total abundance of proteins encoded by a duplicate pair in S. cerevisiae was similar to that of protein encoded by nonduplicated ortholog in Kluyveromyces yeast. Given the frequency of haploinsufficiency, this observation suggests that conserved duplicate genes, even though minor cases of retained duplicates, do not exhibit a dosage effect in yeast, except for ribosomal proteins. Thus, comparative proteomic analyses across multiple species may reveal not only species-specific characteristics of metabolic processes under

  2. Respiration-Dependent Utilization of Sugars in Yeasts: a Determinant Role for Sugar Transporters

    OpenAIRE

    Goffrini, Paola; Ferrero, Iliana; Donnini, Claudia

    2002-01-01

    In many yeast species, including Kluyveromyces lactis, growth on certain sugars (such as galactose, raffinose, and maltose) occurs only under respiratory conditions. If respiration is blocked by inhibitors, mutation, or anaerobiosis, growth does not take place. This apparent dependence on respiration for the utilization of certain sugars has often been suspected to be associated with the mechanism of the sugar uptake step. We hypothesized that in many yeast species, the permease activities fo...

  3. Evolutionary divergence in the fungal response to fluconazole revealed by soft clustering

    KAUST Repository

    Kuo, Dwight; Tan, Kai; Zinman, Guy; Ravasi, Timothy; Bar-Joseph, Ziv; Ideker, Trey

    2010-01-01

    Background: Fungal infections are an emerging health risk, especially those involving yeast that are resistant to antifungal agents. To understand the range of mechanisms by which yeasts can respond to anti-fungals, we compared gene expression patterns across three evolutionarily distant species - Saccharomyces cerevisiae, Candida glabrata and Kluyveromyces lactis - over time following fluconazole exposure. Results: Conserved and diverged expression patterns were identified using a novel soft clustering algorithm that concurrently clusters data from all species while incorporating sequence orthology. The analysis suggests complementary strategies for coping with ergosterol depletion by azoles - Saccharomyces imports exogenous ergosterol, Candida exports fluconazole, while Kluyveromyces does neither, leading to extreme sensitivity. In support of this hypothesis we find that only Saccharomyces becomes more azole resistant in ergosterol-supplemented media; that this depends on sterol importers Aus1 and Pdr11; and that transgenic expression of sterol importers in Kluyveromyces alleviates its drug sensitivity. Conclusions: We have compared the dynamic transcriptional responses of three diverse yeast species to fluconazole treatment using a novel clustering algorithm. This approach revealed significant divergence among regulatory programs associated with fluconazole sensitivity. In future, such approaches might be used to survey a wider range of species, drug concentrations and stimuli to reveal conserved and divergent molecular response pathways.

  4. Evolutionary divergence in the fungal response to fluconazole revealed by soft clustering

    KAUST Repository

    Kuo, Dwight

    2010-07-23

    Background: Fungal infections are an emerging health risk, especially those involving yeast that are resistant to antifungal agents. To understand the range of mechanisms by which yeasts can respond to anti-fungals, we compared gene expression patterns across three evolutionarily distant species - Saccharomyces cerevisiae, Candida glabrata and Kluyveromyces lactis - over time following fluconazole exposure. Results: Conserved and diverged expression patterns were identified using a novel soft clustering algorithm that concurrently clusters data from all species while incorporating sequence orthology. The analysis suggests complementary strategies for coping with ergosterol depletion by azoles - Saccharomyces imports exogenous ergosterol, Candida exports fluconazole, while Kluyveromyces does neither, leading to extreme sensitivity. In support of this hypothesis we find that only Saccharomyces becomes more azole resistant in ergosterol-supplemented media; that this depends on sterol importers Aus1 and Pdr11; and that transgenic expression of sterol importers in Kluyveromyces alleviates its drug sensitivity. Conclusions: We have compared the dynamic transcriptional responses of three diverse yeast species to fluconazole treatment using a novel clustering algorithm. This approach revealed significant divergence among regulatory programs associated with fluconazole sensitivity. In future, such approaches might be used to survey a wider range of species, drug concentrations and stimuli to reveal conserved and divergent molecular response pathways.

  5. Study of atmospheric neutrino interactions and search for nucleon decay in Soudan 2

    Energy Technology Data Exchange (ETDEWEB)

    Leeson, William R. [Tufts Univ., Medford, MA (United States)

    1995-12-14

    Contained event samples, including 30 single-track muon-like events, 35 single-shower electron-like events, and 34 multiprong events, have been obtained from a 1.0 kiloton-year exposure of the Soudan 2 detector. A sample of 15 multiprong events which are partially contained has also been isolated. Properties of these events are used to examine the verity of the atmospheric neutrino flavor ratio anomaly as reported by the Kamiokande and IMB-3 water Cherenkov experiments. The compatibility of the Soudan data with each of two `new physics` explanations for the anomaly, namely proton decay and neutrino oscillations, is investigated. We examine background processes which have not been explicitly treated by the water Cherenkov detectors. Chapters discuss underground non-accelerator particle physics, the atmospheric neutrino anomaly and its interpretation, the Soudan 2 detector and event selection, reconstruction of neutrino events, rock event contamination in Soudan `quasi-elastic` samples, contained multiprong events in Soudan 2, neutrino flavor composition of the multiprong sample, partially contained events in Soudan 2, nucleon decay in Soudan 2, and a summary and discussion.

  6. Study of atmospheric neutrino interactions and search for nucleon decay in Soudan 2

    International Nuclear Information System (INIS)

    Leeson, W.R.

    1995-01-01

    Contained event samples, including 30 single-track muon-like events, 35 single-shower electron-like events, and 34 multiprong events, have been obtained from a 1.0 kiloton-year exposure of the Soudan 2 detector. A sample of 15 multiprong events which are partially contained has also been isolated. Properties of these events are used to examine the verity of the atmospheric neutrino flavor ratio anomaly as reported by the Kamiokande and IMB-3 water Cherenkov experiments. The compatibility of the Soudan data with each of two 'new physics' explanations for the anomaly, namely proton decay and neutrino oscillations, is investigated. We examine background processes which have not been explicitly treated by the water Cherenkov detectors. Chapters discuss underground non-accelerator particle physics, the atmospheric neutrino anomaly and its interpretation, the Soudan 2 detector and event selection, reconstruction of neutrino events, rock event contamination in Soudan 'quasi-elastic' samples, contained multiprong events in Soudan 2, neutrino flavor composition of the multiprong sample, partially contained events in Soudan 2, nucleon decay in Soudan 2, and a summary and discussion. 12 refs., 124 figs., 28 tabs., 7 appendices

  7. b-GALACTOSIDASE IMMOBILIZATION ON CONTROLLED PORE SILICA

    Directory of Open Access Journals (Sweden)

    H. C. Trevisan

    1997-12-01

    Full Text Available The immobilization of b -galactosidase from Kluyveromyces fragilis on controlled pore silica was investigated. Immobilization was performed on amino silica activated with glutaraldehyde and the product was applied to the hydrolysis of lactose of whey. The behaviors of the soluble and immobilized enzyme were compared by using whey and a lactose solution as the substrate. With the aim of optimizing the method, parameters such as the amount of glutaraldehyde and the size of the particles were evaluated by comparing activities and stabilities on batch and continuously fluidized bed reactors

  8. Beta-galactosidase catalyzed selective galactosylation of aromatic compounds.

    Science.gov (United States)

    Bridiau, Nicolas; Taboubi, Selma; Marzouki, Nejib; Legoy, Marie Dominique; Maugard, Thierry

    2006-01-01

    A new approach to galacto-oligosaccharides and galacto-conjugates synthesis performed by the beta-galactosidase from Kluyveromyces lactis is reported. The enzymatic galactosylation of eight kinds of adsorbed aromatic primary alcohols, in particular the two drugs guaifenesin and chlorphenesin, gave the corresponding beta-D-galacto-pyranosides in yields ranging between approximately 10% and 96%. For the first time, we have showed that the adsorption of acceptor substrates onto solid supports such as silica gel influences the yield and the selectivity of galacto-conjugates synthesis. In particular, we observed that adsorption of acceptor favored the synthesis of digalactosylated compounds.

  9. Pyruvate decarboxylases from the petite-negative yeast Saccharomyces kluyveri

    DEFF Research Database (Denmark)

    Møller, Kasper; Langkjær, Rikke Breinhold; Nielsen, Jens

    2004-01-01

    was controlled by variations in the amount of mRNA. The mRNA level and the pyruvate decarboxylase activity responded to anaerobiosis and growth on different carbon sources in essentially the same fashion as in S. cerevisiae. This indicates that the difference in ethanol formation between these two yeasts...... is not due to differences in the regulation of pyruvate decarboxylase(s), but rather to differences in the regulation of the TCA cycle and the respiratory machinery. However, the PDC genes of Saccharomyces/Kluyveromyces yeasts differ in their genetic organization and phylogenetic origin. While S. cerevisiae...

  10. Milk utilization. Part 5. Advances in the production of wine and ethanol from milk

    Energy Technology Data Exchange (ETDEWEB)

    Sienkiewicz, T; Riedel, C L

    1979-01-01

    After defatting, deproteinization, and possible desalting (electrodialysis), the fermentation of sweet and cottage wheys (whole whey, condensed whey, permeate) leads to EtOH and wine and a decrease in sewage loading. The fermentation of whole lactose with Kluyveromyces fragilis occurred after adaption of yeast in 1 L of 100% EtOH from 42 L permeate. The byproduct is a heating gas (methane, CO/sub 2/). After the addition of glucose or sucrose or enzymic cleavage of lactose with beta-galactosidase and fermentation with Saccharomyces cerevisiae a sweet clear wine is produced (10.5% EtOH).

  11. Preparation of D-[U-14C]galactose and α-D-[U-14C]galactose-1-phosphate

    International Nuclear Information System (INIS)

    Kolina, J.; Hromadkova, B.

    1989-01-01

    Optically pure D-[U- 14 C]galactose was prepared on a preparatory scale using the galactokinase enzyme. The suggested procedure allows to also prepare a α-D-[U- 14 C]galactose-1-phosphate and L-[U- 14 ]galactose giving good yield. The experiments proved that the raw fraction isolated from yeast of the Kluyveromyces fragilis strain or the Kluyveromyces lactis strain shows sufficient activity. Phosphorylation of D-[U- 14 C]galactose practically terminates after 30 mins of incubation. DL-[U- 14 C]galactose isolated using preparatory paper chromatography from the acid hydrolyzate of [U- 14 C] polysaccharide is a satisfactory radioactive precursor. The developed preparation procedure theoretically contributed towards the further elucidation of the problem of the proportional representation of galactose stereo-isomers in extracellular polysaccharide isolated from red algae. In this respect data in the literature differ and some sources state a significantly higher propertion of L-galactose. The experiments showed that [U- 14 C] polysaccharide isolated from the red algae Porphyridium cruentum prevalently contains D-[U- 14 C]galactose, which confirms the process of enzyme reaction. (author). 1 tab., 4 refs

  12. Role of killer factors in the inhibitory activity of bio-control yeasts against Penicillium expansum and Aspergillus ochraceus

    Directory of Open Access Journals (Sweden)

    Ciro da Silva Portes

    2013-08-01

    Full Text Available This work evaluated the antagonism of killer positive yeast strains (isolated from 11 samples of different frozen fruit pulps against the strains of Penicillium expansum and Aspergillus ochraceus. Of the total 41 killer yeasts tested in YM agar, 19 showed antibiosis against P. expansum and A. ochraceus, with inhibition zone ranging from 10 to 18 mm and 10 to 19 mm, respectively. In the following step, the extracellular activity of Kluyveromyces sp. FP4(13 was tested performing the assay in YM broth. The antifungal activity of Kluyveromyces sp. FP4(13 cell-free culture supernatant (25ºC/96 h was more effective against the conidia germination, showing inhibition rates of 93.33 and 86.44% for P. expansum and A. ochraceus, respectively. The micelial growth inhibition was 28.45 and 21.0%, respectively. The antagonism showed by the selected yeasts could be used as a promising alternative tool to reduce and control the postharvest fungal spoilage of the fruits. However, further studies should be carried out in order to better elucidate the role of innocuous characters in antagonistic microorganisms, as well as the purification and characterization of new killer toxins.

  13. Production of Palmitoleic and Linoleic Acid in Oleaginous and Nonoleaginous Yeast Biomass

    Directory of Open Access Journals (Sweden)

    Irena Kolouchová

    2016-01-01

    Full Text Available We investigated the possibility of utilizing both oleaginous yeast species accumulating large amounts of lipids (Yarrowia lipolytica, Rhodotorula glutinis, Trichosporon cutaneum, and Candida sp. and traditional biotechnological nonoleaginous ones (Kluyveromyces polysporus, Torulaspora delbrueckii, and Saccharomyces cerevisiae as potential producers of dietetically important major fatty acids. The main objective was to examine the cultivation conditions that would induce a high ratio of dietary fatty acids and biomass. Though genus-dependent, the type of nitrogen source had a higher influence on biomass yield than the C/N ratio. The nitrogen source leading to the highest lipid accumulation was potassium nitrate, followed by ammonium sulfate, which is an ideal nitrogen source supporting, in both oleaginous and nonoleaginous species, sufficient biomass growth with concomitantly increased lipid accumulation. All yeast strains displayed high (70–90% content of unsaturated fatty acids in total cell lipids. The content of dietary fatty acids of interest, namely, palmitoleic acid and linoleic acid, reached in Kluyveromyces and Trichosporon strains over 50% of total fatty acids and the highest yield, over 280 mg per g of dry cell weight of these fatty acids, was observed in Trichosporon with ammonium sulfate as nitrogen source at C/N ratio 70.

  14. Antimicrobial Activity of Six Pomegranate (Punica granatum L. Varieties and Their Relation to Some of Their Pomological and Phytonutrient Characteristics

    Directory of Open Access Journals (Sweden)

    Nurcan Erbil

    2009-05-01

    Full Text Available Arils from six pomegranate (Punica granatum L. varieties grown in the Mediterranean region of Turkey were tested for their antimicrobial properties by the agar diffusion and minimum inhibitory concentration (MIC methods against seven bacteria: (Bacillus megaterium DSM 32, Pseudomonas aeruginosa DSM 9027, Staphylococcus aureus Cowan 1, Corynebacterium xerosis UC 9165, Escherichia coli DM, Enterococcus faecalis A10, Micrococcus luteus LA 2971, and threefungi (Kluvyeromyces marxianus A230, Rhodotorula rubra MC12, Candida albicans ATCC 1023. It has been observed that the pomegranate aril extracts had antimicrobial effect on all microorganisms, giving inhibition zones ranging in size from 13 to 26 mm. The MIC values for active pomegranate extracts ranged between 30 and >90 µg/mL. The results obtained appeared to confirm the antimicrobial potential of the Punica granatum varieties.

  15. Ensiling – Wet-storage method for lignocellulosic biomass for bioethanol production

    DEFF Research Database (Denmark)

    Oleskowicz-Popiel, Piotr; Thomsen, Anne Belinda; Schmidt, Jens Ejbye

    2011-01-01

    , and consequently by lowing pH, inhibiting other microbes to degrade the polysaccharides. Following silage treatment, enzymatic convertibility tests showed that 51.5%, 36.5%, and 41.9% of the cellulose was converted by cellulytic enzymes in ensiled maize, rye, and clover grass, respectively. In addition, tests......Ensiling of humid biomass samples wrapped in plastic bales has been investigated as a wet-storage for bioethanol production from three lignocellulosic biomass samples i.e. maize, rye, and clover grass. During the silage process, lactic acid bacteria fermented free sugars to lactic acid.......5% (by S. cerevisiae); the yields significantly increased after hydrothermal pretreatment: 77.7%, 72.8%, 79.5% (by K. marxianus) and 72.0%, 80.7%, 75.7% (by S. cerevisiae) of the theoretical based on the C6 sugar contents in maize, rye, and clover grass, respectively....

  16. Steady-state and transient-state analyses of aerobic fermentation in Saccharomyces kluyveri

    DEFF Research Database (Denmark)

    Møller, Kasper; Bro, Christoffer; Piskur, Jure

    2002-01-01

    Some yeasts, such as Saccharomyces cerevisiae, produce ethanol at fully aerobic conditions, whereas other yeasts, such as Kluyveromyces lactis, do not. In this study we investigated the occurrence of aerobic alcoholic fermentation in the petite-negative yeast Saccharomyces kluyveri that is only...... distantly related to S. cerevisiae. In aerobic glucose-limited continuous cultures of S. kluyveri, two growth regimens were observed: at dilution rates below 0.5 h(-1) the metabolism was purely respiratory, and at dilution rates above 0.5 h-1 the metabolism was respiro-fermentative. The dilution rate...... a delay of 20-50 min (depending on culture conditions prior to the pulse), which is in contrast to S. cerevisiae that ferments immediately after glucose addition....

  17. Selection of yeast able to produce ethanol from glucose at 40/sup 0/C

    Energy Technology Data Exchange (ETDEWEB)

    Hacking, A J; Taylor, I W.F.; Hanas, C M

    1984-05-01

    A total of 55 yeast strains selected from 7 genera known to ferment carbohydrates to ethanol were screened for their ability to ferment glucose to ethanol in shaken flask culture at 37/sup 0/, 40/sup 0/ and 45/sup 0/C. Yields of more than 50% of the theoretical maximum were obtained with 28 strains at 37/sup 0/C, but only 12 at 40/sup 0/C. Only 6 could grow at 45/sup 0/C, but they produced poor yields. In general Kluyveromyces strains were more thermotolerant than Saccharomyces and Candida strains, but Saccharomyces strains produced higher ethanol yields. The 8 strains with the highest yields at 40/sup 0/C were evaluated in batch fermentations. Three of these, two Saccharomyces and one Candida, were able to meet minimum commercial targets set at 8% (v/v) ethanol from 14% (w/v) glucose at 40/sup 0/C.

  18. PMAA-stabilized ferrofluid/chitosan/yeast composite for bioapplications

    International Nuclear Information System (INIS)

    Baldikova, Eva; Prochazkova, Jitka; Stepanek, Miroslav; Hajduova, Jana; Pospiskova, Kristyna; Safarikova, Mirka; Safarik, Ivo

    2017-01-01

    A simple, one-pot process for the preparation of magnetically responsive yeast-based biocatalysts was developed. Saccharomyces cerevisiae, Candida utilis and Kluyveromyces lactis cells were successfully incorporated into chitosan gel magnetically modified with poly(methacrylic acid)-stabilized magnetic fluid (PMAA-FF) during its formation. Magnetic PMAA-FF/chitosan/yeast composites were efficiently employed for invert sugar production. The dependence of invertase activity on used yeast, amount of magnetic biocatalyst, agitation time and after reuse was studied in detail. The tested magnetic biocatalysts retained at least 69% of their initial activity after 8 reuse cycles. - Highlights: • New types of magnetically responsive yeast biocomposites were prepared. • Recently developed PMAA-stabilized magnetic fluid was used. • Three yeast species were entrapped into magnetic chitosan gel during its formation. • All biocatalysts were efficiently employed for invert sugar formation.

  19. A phylogenetic analysis of the sugar porters in hemiascomycetous yeasts.

    Science.gov (United States)

    Palma, Margarida; Goffeau, André; Spencer-Martins, Isabel; Baret, Philippe V

    2007-01-01

    A total of 214 members of the sugar porter (SP) family (TC 2.A.1.1) from eight hemiascomycetous yeasts: Saccharomyces cerevisiae, Candida glabrata, Kluyveromyces lactis, Ashbya (Eremothecium) gossypii, Debaryomyces hansenii, Yarrowia lipolytica, Candida albicans and Pichia stipitis, were identified. The yeast SPs were classified in 13 different phylogenetic clusters. Specific sugar substrates could be allocated to nine phylogenetic clusters, including two novel TC clusters that are specific to fungi, i.e. the glycerol:H(+) symporter (2.A.1.1.38) and the high-affinity glucose transporter (2.A.1.1.39). Four phylogenetic clusters are identified by the preliminary fifth number Z23, Z24, Z25 and Z26 and the substrates of their members remain undetermined. The amplification of the SP clusters across the Hemiascomycetes reflects adaptation to specific carbon and energy sources available in the habitat of each yeast species. (c) 2007 S. Karger AG, Basel.

  20. NUMERICAL SOLUTION OF STEADY STATE DISPERSION FLOW MODEL FOR LACTOSE-LACTASE HYDROLYSIS WITH DIFFERENT KINETICS IN FIXED BED

    Directory of Open Access Journals (Sweden)

    OLAOSEBIKAN ABIDOYE OLAFADEHAN

    2010-06-01

    Full Text Available A detailed computational procedure for evaluating lactose hydrolysis with immobilized enzyme in a packed bed tubular reactor under dispersion flow conditions is presented. The dispersion flow model for lactose hydrolysis using different kinetics, taking cognizance of external mass transfer resistances, was solved by the method of orthogonal collocation. The reliability of model simulations was tested using experimental data from a laboratory packed bed column, where the -galactosidase of Kluyveromyces fragilis was immobilized on spherical chitosan beads. Comparison of the simulated results with experimental exit conversion shows that the dispersion flow model and using Michaelis-Menten kinetics with competitive product (galactose inhibition are appropriate to interpret the experimental results and simulate the process of lactose hydrolysis in a fixed bed.

  1. Glucose-free fructose production from Jerusalem artichoke using a recombinant inulinase-secreting Saccharomyces cerevisiae strain.

    Science.gov (United States)

    Yu, Jing; Jiang, Jiaxi; Ji, Wangming; Li, Yuyang; Liu, Jianping

    2011-01-01

    Using inulin (polyfructose) obtained from Jerusalen artichokes, we have produced fructose free of residual glucose using a recombinant inulinase-secreting strain of Saccharomyces cerevisiae in a one-step fermentation of Jerusalem artichoke tubers. For producing fructose from inulin, a recombinant inulinase-producing Saccharomyce cerevisiae strain was constructed with a deficiency in fructose uptake by disruption of two hexokinase genes hxk1 and hxk2. The inulinase gene introduced into S. cerevisiae was cloned from Kluyveromyces cicerisporus. Extracellular inulinase activity of the recombinant hxk-mutated S. cerevisiae strain reached 31 U ml(-1) after 96 h growth. When grown in a medium containing Jerusalem artichoke tubers as the sole component without any additives, the recombinant yeast accumulated fructose up to 9.2% (w/v) in the fermentation broth with only 0.1% (w/v) glucose left after 24 h.

  2. Dicty_cDB: Contig-U11295-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 382126 |pid:none) Kluyveromyces lactis strain NRRL... 120 1e-25 BC122690_1( BC122690 |pid:none) Bos taurus transcription term...ns RNA polymerase II ter... 119 2e-25 (Q9UNY4) RecName: Full=Transcription termination factor 2; ... 119 ...345( CU633901 |pid:none) Podospora anserina genomic DNA c... 116 2e-24 (Q5NC05) RecName: Full=Transcription term...|pid:none) Mus musculus transcription termina... 115 2e-24 AL596125_1( AL596125 |pid:none) Mouse DNA sequenc...se (hZF... 115 4e-24 ( P34739 ) RecName: Full=Transcription termination factor 2;

  3. Microbial terroir and food innovation: The case of yeast biodiversity in wine.

    Science.gov (United States)

    Capozzi, Vittorio; Garofalo, Carmela; Chiriatti, Maria Assunta; Grieco, Francesco; Spano, Giuseppe

    2015-12-01

    Saccharomyces and non-Saccharomyces represents a heterogeneous class in the grape/must/wine environments including several yeast genera (e.g., Saccharomyces, Hanseniaspora, Pichia, Candida, Metschnikowia, Kluyveromyces, Zygosaccharomyces, Torulaspora, Dekkera and Schizosaccharomyces) and species. Since, each species may differently contribute to the improvement/depreciation of wine qualities, it appears clear the reason why species belong to non-Saccharomyces are also considered a biotechnological resource in wine fermentation. Here, we briefly review the oenological significance of this specific part of microbiota associated with grapes/musts/wine. Moreover, the diversity of cultivable non-Saccharomyces genera and their contribute to typical wines fermentations will be discussed. Copyright © 2015 Elsevier GmbH. All rights reserved.

  4. PMAA-stabilized ferrofluid/chitosan/yeast composite for bioapplications

    Energy Technology Data Exchange (ETDEWEB)

    Baldikova, Eva, E-mail: baldie@email.cz [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Department of Applied Chemistry, Faculty of Agriculture, University of South Bohemia, Branisovska 1457, 370 05 Ceske Budejovice (Czech Republic); Prochazkova, Jitka [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Stepanek, Miroslav; Hajduova, Jana [Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague 2 (Czech Republic); Pospiskova, Kristyna [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 27, 783 71 Olomouc (Czech Republic); Safarikova, Mirka [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Department of Nanobiotechnology, Biology Centre, CAS, ISB, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Safarik, Ivo [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 27, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Biology Centre, CAS, ISB, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

    2017-04-01

    A simple, one-pot process for the preparation of magnetically responsive yeast-based biocatalysts was developed. Saccharomyces cerevisiae, Candida utilis and Kluyveromyces lactis cells were successfully incorporated into chitosan gel magnetically modified with poly(methacrylic acid)-stabilized magnetic fluid (PMAA-FF) during its formation. Magnetic PMAA-FF/chitosan/yeast composites were efficiently employed for invert sugar production. The dependence of invertase activity on used yeast, amount of magnetic biocatalyst, agitation time and after reuse was studied in detail. The tested magnetic biocatalysts retained at least 69% of their initial activity after 8 reuse cycles. - Highlights: • New types of magnetically responsive yeast biocomposites were prepared. • Recently developed PMAA-stabilized magnetic fluid was used. • Three yeast species were entrapped into magnetic chitosan gel during its formation. • All biocatalysts were efficiently employed for invert sugar formation.

  5. Genome and transcriptome analysis of the food-yeast Candida utilis.

    Directory of Open Access Journals (Sweden)

    Yasuyuki Tomita

    Full Text Available The industrially important food-yeast Candida utilis is a Crabtree effect-negative yeast used to produce valuable chemicals and recombinant proteins. In the present study, we conducted whole genome sequencing and phylogenetic analysis of C. utilis, which showed that this yeast diverged long before the formation of the CUG and Saccharomyces/Kluyveromyces clades. In addition, we performed comparative genome and transcriptome analyses using next-generation sequencing, which resulted in the identification of genes important for characteristic phenotypes of C. utilis such as those involved in nitrate assimilation, in addition to the gene encoding the functional hexose transporter. We also found that an antisense transcript of the alcohol dehydrogenase gene, which in silico analysis did not predict to be a functional gene, was transcribed in the stationary-phase, suggesting a novel system of repression of ethanol production. These findings should facilitate the development of more sophisticated systems for the production of useful reagents using C. utilis.

  6. Modelling of the process yields of a whey fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Blakebrough, N; Moresi, M

    1981-09-01

    The biomass yields (y) and COD reduction efficiencies (eta) of a whey fermentation by Kluyveromyces fragilis were studied in a 100-l fermenter at various stirrer speeds and lactose concentrations, and compared to those obtained in 10-l and 15-l fermenters at constant values of the oxygen transfer coefficient (ksub(L)a) and air velocity. The empirical models previously constructed by using the 15-l fermenter data could be used to predict the yields on the other scales by calculating for each run the 15-l fermenter which would provide the same oxygen transfer coefficient measured by the sulphite method on each fermenter under study. To make this model independent of stirrer speeds used in each generic fermenter, the effect of aeration and mixing was incorporated into an overall parameter (ksub(L)a) and the values of y and eta were correlated only with temperature, lactose level and ksub(L)a since these variables were approximately orthogonal.

  7. Chemical oxygen demand reduction in a whey fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Moresi, M; Colicchio, A; Sansovini, F; Sebastiani, E

    1980-01-01

    The efficiency of COD reduction in the fermentation of whey by Kluyveromyces fragilis IMAT 1872 was studied at various temperatures, lactose concentrations, air dilution ratios, and stirring speeds. Two different optimal sets of these variables were found according to whether the objective was the production of cell mass or the reduction of COD. The 2 sets were then compared to establish a strategy for the industrial development of this fermentation process. The experimental efficiencies of COD removal were submitted to analysis in a composite design. Only the O2 transfer coefficient factor and the stripping factor were significant. Therefore, the observations were fitted with a quadratic expression by using only these factors: the mean std. error was <6%. The yield of cells varied in this fermentation, but this parameter may be particularly useful for analyzing and optimizing any fermentation process when the culture medium is a mixture of carbohydrates or the main substrate is fully utilized during the initial stages of fermentation.

  8. 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.

  9. Microbiological and biochemical aspects of Camembert-type cheeses depend on atmospheric composition in the ripening chamber.

    Science.gov (United States)

    Leclercq-Perlat, M-N; Picque, D; Riahi, H; Corrieu, G

    2006-08-01

    Camembert-type cheeses were prepared from pasteurized milk seeded with Kluyveromyces lactis, Geotrichum candidum, Penicillium camemberti, and Brevibacterium aurantiacum. Microorganism growth and biochemical dynamics were studied in relation to ripening chamber CO(2) atmospheric composition using 31 descriptors based on kinetic data. The chamber ripening was carried out under 5 different controlled atmospheres: continuously renewed atmosphere, periodically renewed atmosphere, no renewed atmosphere, and 2 for which CO(2) was either 2% or 6%. All microorganism dynamics depended on CO(2) level. Kluyveromyces lactis was not sensitive to CO(2) during its growth phases, but its death did depend on it. An increase of CO(2) led to a significant improvement in G. candidum. Penicillium camemberti mycelium development was enhanced by 2% CO(2). The equilibrium between P. camemberti and G. candidum populations was disrupted in favor of the yeast when CO(2) was higher than 4%. Growth of B. aurantiacum depended more on O(2) than on CO(2). Two ripening progressions were observed in relation to the presence of CO(2) at the beginning of ripening: in the presence of CO(2), the ripening was fast-slow, and in the absence of CO(2), it was slow-fast. The underrind was too runny if CO(2) was equal to or higher than 6%. The nitrogen substrate progressions were slightly related to ripening chamber CO(2) and O(2) levels. During chamber ripening, the best atmospheric condition to produce an optimum between microorganism growth, biochemical dynamics, and cheese appearance was a constant CO(2) level close to 2%.

  10. On the biotechnology of plants with fructosan content

    Energy Technology Data Exchange (ETDEWEB)

    Klaushofer, H.

    1986-03-01

    Inulin, as to its chemical nature, is a polyfructosane. Fructosanes (fructanes) are hardly less abundant in nature than starch. However, there are only few plants with sufficient fructosane content for technological utilization. The most important of them are Jerusalem artichoke and chicory. At first this paper deals with inulin and the homologous series of fructosanes. The importance of Jerusalem artichoke and chicory as agricultural crops and their respective peculiarities are pointed out as far as they are relevant for their use as technical source materials. Inulin containing plants are of interest with respect to the production of fructose and fructose syrup and as energy plants (production of ethanol). Chicory is particularly suitable as source material for fructose-(syrup-)production, Jerusalem artichoke mainly for the production of ethanol, although principally both product groups can be obtained from chicory roots and from topinambur bulbs. If inulin containing raw materials are used for ethanol production, it's of interest that yeast invertase splits polyfructosanes of higher molecular mass considerably more slowly than inulinase and yields are less satisfactory with S. cerevisiae and increasing inulin content in the mash. If yeast types are used containing inulinase and invertase, e.g. Kl. fragilis and marxianus, satisfactory fermentation can be obtained even with these types of mashes.

  11. Antimicrobial Activity of Essential Oils Extracted from Gamma Irradiated and Stored Anise (Pimenella Anisum) and Black Cumin (Negilla Sativa) Seeds

    International Nuclear Information System (INIS)

    Mohamed, G.A.

    2011-01-01

    Anise and black cumin seeds were gamma irradiated to doses of 5, 10, 20 and 40 kGy then these seeds were stored to periods of 0, 4, 8 and 12 months. In all treatments, essential oils were extracted at concentrations 500, 1000, 2000, 4000 and 6000 ppm. The inhibitory effect of the different oil concentrations was tested against some microorganism which included bacteria (E. coli and B. cereus), fungi (A. niger and P. citrinum) and yeast (S. lypoytica and K. marxianus). Each of the extracted oil showed different magnitudes to inhibit the growth of the tested microorganisms. However, exposing the aromatic seeds to gamma irradiation before oil extraction was resulted in stimulation in the biological activity of the produced oil. Maximum stimulation was exerted at irradiation dose of 20 kGy. However, the antimicrobial activity of the tested oils was relatively declined when seeds were stored up to 12 months but this decrease was counteracted when seeds were irradiated before storage, thus, gamma radiation showed a beneficial impact to maintain the biological activity of the essential oils during seeds storage.

  12. Novel high-performance metagenome β-galactosidases for lactose hydrolysis in the dairy industry.

    Science.gov (United States)

    Erich, Sarah; Kuschel, Beatrice; Schwarz, Thilo; Ewert, Jacob; Böhmer, Nico; Niehaus, Frank; Eck, Jürgen; Lutz-Wahl, Sabine; Stressler, Timo; Fischer, Lutz

    2015-09-20

    The industrially utilised β-galactosidases from Kluyveromyces spp. and Aspergillus spp. feature undesirable kinetic properties in praxis, such as an unsatisfactory lactose affinity (KM) and product inhibition (KI) by galactose. In this study, a metagenome library of about 1.3 million clones was investigated with a three-step activity-based screening strategy in order to find new β-galactosidases with more favourable kinetic properties. Six novel metagenome β-galactosidases (M1-M6) were found with an improved lactose hydrolysis performance in original milk when directly compared to the commercial β-galactosidase from Kluyveromyces lactis (GODO-YNL2). The best metagenome candidate, called "M1", was recombinantly produced in Escherichia coli BL21(DE3) in a bioreactor (volume 35 L), resulting in a total β-galactosidase M1 activity of about 1100 μkatoNPGal,37 °C L(-1). Since milk is a sensitive and complex medium, it has to be processed at 5-10 °C in the dairy industry. Therefore, the β-galactosidase M1 was tested at 8 °C in milk and possessed a good stability (t1/2=21.8 d), a desirably low apparent KM,lactose,8 °C value of 3.8±0.7 mM and a high apparent KI,galactose,8 °C value of 196.6±55.5 mM. A lactose hydrolysis process (milk, 40 nkatlactose mLmilk,8 °C(-1)) was conducted at a scale of 0.5L to compare the performance of M1 with the commercial β-galactosidase from K. lactis (GODO-YNL2). Lactose was completely (>99.99%) hydrolysed by M1 and to 99.6% (w/v) by K. lactis β-galactosidase after 25 h process time. Thus, M1 was able to achieve the limit of lactose per litre milk, which is recommended for dairy products labelled as "lactose-free". Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  13. Identification and enzymatic characterization of the yeasts isolated from Erzincan tulum cheese

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    S. Karasu-Yalcin

    2012-03-01

    Full Text Available In this study, 146 yeast isolates were obtained from 45 Erzincan tulum cheese samples. By using API ID 32C test system and some complementary morphological, physiological and biochemica tests, 121 of the isolates could be identified at species level, while 12 of them were identified at genus level. The identified yeast isolates belonged to six different genera which were Candida, Geotrichum, Kluyveromyces, Pichia, Saccharomyces and Zygosaccharomyces. The most aboundant species was C. lambica, followed by C. zeylanoides, C. famata var. famata, G. candidum and C. kefyr. Enzymatic characterization of the strains was determined by using API-ZYM test system. All of the isolates had leucin arylamidase activity. Eight strains belonging to S. cerevisiae, Z. mellis, G. candidum and P. fermentans were found to have high leucin arylamidase activities. Most of the isolates had β-galactosidase, acid phosphatase and esterase lipase (C8 activities. Eight investigated C. lambica strains had high acid phosphatase activities. Such enzymatic properties of investigated yeast isolates could be fundamental factor for their application as starter culture candidates in production of Erzincan tulum cheese. It was demonstrated that the strain C. lambica T103 had superior enzymatic characteristics with the potential to be used in further technological investigations as an adjunct starter.

  14. Encapsulation of Platelet in Kefiran Polymer and Detection of Bioavailability of Immobilized Platelet in Probiotic Kefiran as A New Drug for Surface Bleeding

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    Anahita Jenab

    2015-11-01

    Full Text Available Background : Kefir contains lactic acid bacteria (Lactobacillus, Lactococcus, Leuconostoc, Acetobacter and Streptococcus and yeasts (Kluyveromyces, Torula, Candida, Saccharomyces .Kefiran is the polysaccharide produced by lactic acid bacteria in kefir.Methods : Kefiran was prepared from milk containing 0.5% fat and 10 grams kefir grains and was separated from kefir by ethanol (0.02 gram following entrapping the platelets to this polymer. Ligand of the platelet-polysaccharide was studied by FTIR.Results : FTIR results showed that the bands of C-O and C-O-C connections were formed and the polysaccharides had been attached to the receptors of the platelet glycoproteins (GP Ib,GPIIb / IIIa. Stability and encapsulation of the platelet and kefiran were assessed by Coulter Counter. Encapsulation of the platelets by polysaccharide at the beginning caused to reduce the number of platelets following by releasing of 50% of the platelets after 3 hours.Conclusion : The platelets were encapsulated in kefiran polymer and detected for bioavailability as new drug for surface bleeding. Also, kefiran has antimicrobial and antifungal properties. On the other hand, the existence of nisin in kefiran could be useful as an antibacterial lantibiotic. 

  15. Changes in volatile profile of soybean residue (okara) upon solid-state fermentation by yeasts.

    Science.gov (United States)

    Vong, Weng Chan; Liu, Shao-Quan

    2017-01-01

    Soybean residue (okara), a by-product of soymilk, is produced in large volumes by the soy food industry and is often discarded due to its undesirable flavour. As it contains a considerable amount of protein and fats, biotransformation of okara to improve its flavour presents an opportunity for alternative utilisation. This paper evaluated 10 yeasts in the solid-state fermentation of okara based on their volatile profiles as analysed with HS-SPME GC-MS/FID. Four 'dairy yeasts' (Geotrichum candidum, Yarrowia lipolytica, Debaryomyces hansenii and Kluyveromyces lactis) and six 'wine yeasts' (Saccharomyces cerevisiae, Lachancea thermotolerans, Metschnikowia pulcherrima, Pichia kluyveri, Torulaspora delbrueckii, and Williopsis saturnus) were studied. The main off-odourants in okara, hexanal and trans-2-hexenal, significantly decreased after fermentation due to their bioconversion into methyl ketones and/or esters. The okara fermented by dairy yeasts contained greater proportions of methyl ketones, while that by wine yeasts contained more ethyl and acetyl esters. Notably, the okara fermented by W. saturnus contained 13 esters and the total GC-FID peak area of esters was about 380 times that in fresh okara, leading to a perceptible fruity note. Okara can be exploited as an inexpensive substrate for bioflavour extraction and/or a more pleasant food ingredient via yeast fermentation. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  16. Genetic, genomic, and molecular tools for studying the protoploid yeast, L. waltii.

    Science.gov (United States)

    Di Rienzi, Sara C; Lindstrom, Kimberly C; Lancaster, Ragina; Rolczynski, Lisa; Raghuraman, M K; Brewer, Bonita J

    2011-02-01

    Sequencing of the yeast Kluyveromyces waltii (recently renamed Lachancea waltii) provided evidence of a whole genome duplication event in the lineage leading to the well-studied Saccharomyces cerevisiae. While comparative genomic analyses of these yeasts have proven to be extremely instructive in modeling the loss or maintenance of gene duplicates, experimental tests of the ramifications following such genome alterations remain difficult. To transform L. waltii from an organism of the computational comparative genomic literature into an organism of the functional comparative genomic literature, we have developed genetic, molecular and genomic tools for working with L. waltii. In particular, we have characterized basic properties of L. waltii (growth, ploidy, molecular karyotype, mating type and the sexual cycle), developed transformation, cell cycle arrest and synchronization protocols, and have created centromeric and non-centromeric vectors as well as a genome browser for L. waltii. We hope that these tools will be used by the community to follow up on the ideas generated by sequence data and lead to a greater understanding of eukaryotic biology and genome evolution. 2010 John Wiley & Sons, Ltd.

  17. Fragile genomic sites are associated with origins of replication.

    Science.gov (United States)

    Di Rienzi, Sara C; Collingwood, David; Raghuraman, M K; Brewer, Bonita J

    2009-09-09

    Genome rearrangements are mediators of evolution and disease. Such rearrangements are frequently bounded by transfer RNAs (tRNAs), transposable elements, and other repeated elements, suggesting a functional role for these elements in creating or repairing breakpoints. Though not well explored, there is evidence that origins of replication also colocalize with breakpoints. To investigate a potential correlation between breakpoints and origins, we analyzed evolutionary breakpoints defined between Saccharomyces cerevisiae and Kluyveromyces waltii and S. cerevisiae and a hypothetical ancestor of both yeasts, as well as breakpoints reported in the experimental literature. We find that origins correlate strongly with both evolutionary breakpoints and those described in the literature. Specifically, we find that origins firing earlier in S phase are more strongly correlated with breakpoints than are later-firing origins. Despite origins being located in genomic regions also bearing tRNAs and Ty elements, the correlation we observe between origins and breakpoints appears to be independent of these genomic features. This study lays the groundwork for understanding the mechanisms by which origins of replication may impact genome architecture and disease.

  18. Brazilian kefir: structure, microbial communities and chemical composition

    Science.gov (United States)

    Magalhães, Karina Teixeira; de Melo Pereira, Gilberto Vinícius; Campos, Cássia Roberta; Dragone, Giuliano; Schwan, Rosane Freitas

    2011-01-01

    Microbial ecology and chemical composition of Brazilian kefir beverage was performed. The microorganisms associated with Brazilian kefir were investigated using a combination of phenotypic and genotypic methods. A total of 359 microbial isolates were identified. Lactic acid bacteria (60.5%) were the major isolated group identified, followed by yeasts (30.6%) and acetic acid bacteria (8.9%). Lactobacillus paracasei (89 isolates), Lactobacillus parabuchneri (41 isolates), Lactobacillus casei (32 isolates), Lactobacillus kefiri (31 isolates), Lactococcus lactis (24 isolates), Acetobacter lovaniensis (32 isolates), Kluyveromyces lactis (31 isolates), Kazachstania aerobia (23 isolates), Saccharomyces cerevisiae (41 isolates) and Lachancea meyersii (15 isolates) were the microbial species isolated. Scanning electron microscopy showed that the microbiota was dominated by bacilli (short and curved long) cells growing in close association with lemon-shaped yeasts cells. During the 24 h of fermentation, the protein content increased, while lactose and fat content decreased. The concentration of lactic acid ranged from 1.4 to 17.4 mg/ml, and that of acetic acid increased from 2.1 to 2.73 mg/ml. The production of ethanol was limited, reaching a final mean value of 0.5 mg/ml. PMID:24031681

  19. The use of controlled microbial cenoses in producers' link to increase steady functioning of artificial ecosystems

    Science.gov (United States)

    Somova, Lydia; Mikheeva, Galina; Somova, Lydia

    The life support systems (LSS) for long-term missions are to use cycling-recycling systems, including biological recycling. Simple ecosystems include 3 links: producers (plants), consumers (man, animals) and reducers (microorganisms). Microorganisms are substantial component of every link of LSS. Higher plants are the traditional regenerator of air and producer of food. They should be used in many successive generations of their reproduction in LSS. Controlled microbiocenoses can increase productivity of producer's link and protect plants from infections. The goal of this work was development of methodological bases of formation of stable, controlled microbiocenoses, intended for increase of productivity of plants and for obtaining ecologically pure production of plants. Main results of our investigations: 1. Experimental microbiocenoses, has been produced in view of the developed methodology on the basis of natural association of microorganisms by long cultivation on specially developed medium. Dominating groups are bacteria of genera: Lactobacillus, Streptococcus, Leuconostoc, Bifidobacterium, Rhodopseudomonas and yeast of genera: Kluyveromyces, Saccharomyces, Torulopsis. 2. Optimal parameters of microbiocenosis cultivation (t, pH, light exposure, biogenic elements concentrations) were experimentally established. Conditions of cultivation on which domination of different groups of microbiocenosis have been found. 3. It was shown, that processing of seeds of wheat, oats, bulbs and plants Allium cepa L. (an onions) with microbial association raised energy of germination of seeds and bulbs and promoted the increase (on 20-30 %) of growth green biomass and root system of plants in comparison with the control. This work is supported by grant, Yenissey , 07-04-96806

  20. Potential benefits of the application of yeast starters in table olive processing.

    Science.gov (United States)

    Arroyo-López, Francisco N; Romero-Gil, Verónica; Bautista-Gallego, Joaquín; Rodríguez-Gómez, Francisco; Jiménez-Díaz, Rufino; García-García, Pedro; Querol, Amparo; Garrido-Fernández, Antonio

    2012-01-01

    Yeasts play an important role in the food and beverage industry, especially in products such as bread, wine, and beer, among many others. However, their use as a starter in table olive processing has not yet been studied in detail. The candidate yeast strains should be able to dominate fermentation, together with lactic acid bacteria, but should also provide a number of beneficial advantages. Technologically, yeasts should resist low pH and high salt concentrations, produce desirable aromas, improve lactic acid bacteria growth, and inhibit spoilage microorganisms. Nowadays, they are being considered as probiotic agents because many species are able to resist the passage through the gastrointestinal tract and show favorable effects on the host. In this way, yeasts may improve the health of consumers by means of the degradation of non-assimilated compounds (such as phytate complexes), a decrease in cholesterol levels, the production of vitamins and antioxidants, the inhibition of pathogens, an adhesion to intestinal cell line Caco-2, and the maintenance of epithelial barrier integrity. Many yeast species, usually found in table olive processing (Wickerhamomyces anomalus, Saccharomyces cerevisiae, Pichia membranifaciens, and Kluyveromyces lactis, among others), have exhibited some of these properties. Thus, the selection of the most appropriate strains to be used as starters in this fermented vegetable, alone or in combination with lactic acid bacteria, is a promising research line to develop in the near future.

  1. Potential benefits of the application of yeast starters in table olive processing

    Science.gov (United States)

    Arroyo-López, Francisco N.; Romero-Gil, Verónica; Bautista-Gallego, Joaquín; Rodríguez-Gómez, Francisco; Jiménez-Díaz, Rufino; García-García, Pedro; Querol, Amparo; Garrido-Fernández, Antonio

    2012-01-01

    Yeasts play an important role in the food and beverage industry, especially in products such as bread, wine, and beer, among many others. However, their use as a starter in table olive processing has not yet been studied in detail. The candidate yeast strains should be able to dominate fermentation, together with lactic acid bacteria, but should also provide a number of beneficial advantages. Technologically, yeasts should resist low pH and high salt concentrations, produce desirable aromas, improve lactic acid bacteria growth, and inhibit spoilage microorganisms. Nowadays, they are being considered as probiotic agents because many species are able to resist the passage through the gastrointestinal tract and show favorable effects on the host. In this way, yeasts may improve the health of consumers by means of the degradation of non-assimilated compounds (such as phytate complexes), a decrease in cholesterol levels, the production of vitamins and antioxidants, the inhibition of pathogens, an adhesion to intestinal cell line Caco-2, and the maintenance of epithelial barrier integrity. Many yeast species, usually found in table olive processing (Wickerhamomyces anomalus, Saccharomyces cerevisiae, Pichia membranifaciens, and Kluyveromyces lactis, among others), have exhibited some of these properties. Thus, the selection of the most appropriate strains to be used as starters in this fermented vegetable, alone or in combination with lactic acid bacteria, is a promising research line to develop in the near future.

  2. Utilization of whey powder as substrate for low-cost preparation of β-galactosidase as main product, and ethanol as by-product, by a litre-scale integrated process.

    Science.gov (United States)

    You, Shengping; Chang, Hongxing; Yin, Qingdian; Qi, Wei; Wang, Mengfan; Su, Rongxin; He, Zhimin

    2017-12-01

    Whey powder, a by-product of dairy industry, is an attractive raw material for value-added products. In this study, utilization of whey powder as substrate for low-cost preparation of β-galactosidase as main product and ethanol as by-product were investigated by a litre-scale integrated strategy, encompassing fermentation, isolation, permeabilization and spray drying. Firstly, through development of low-cost industrial culture and fed-batch strategies by Kluyveromyces lactis, 119.30U/mL β-galactosidase activity and 16.96mg/mL by-product ethanol were achieved. Afterward, an up-dated mathematic model for the recycling permeabilization was established successfully and 30.4g cells sediment isolated from 5L fermentation broth were permeabilized completely by distilled ethanol from broth supernatant. Then β-galactosidase product with 5.15U/mg from protection of gum acacia by spray drying was obtained. Furthermore, by-product ethanol with 31.08% (v/v) was achieved after permeabilization. Therefore, the integrated strategy using whey powder as substrate is a feasible candidate for industrial-scale implementation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Structure-function insights into direct lipid transfer between membranes by Mmm1-Mdm12 of ERMES.

    Science.gov (United States)

    Kawano, Shin; Tamura, Yasushi; Kojima, Rieko; Bala, Siqin; Asai, Eri; Michel, Agnès H; Kornmann, Benoît; Riezman, Isabelle; Riezman, Howard; Sakae, Yoshitake; Okamoto, Yuko; Endo, Toshiya

    2018-03-05

    The endoplasmic reticulum (ER)-mitochondrial encounter structure (ERMES) physically links the membranes of the ER and mitochondria in yeast. Although the ER and mitochondria cooperate to synthesize glycerophospholipids, whether ERMES directly facilitates the lipid exchange between the two organelles remains controversial. Here, we compared the x-ray structures of an ERMES subunit Mdm12 from Kluyveromyces lactis with that of Mdm12 from Saccharomyces cerevisiae and found that both Mdm12 proteins possess a hydrophobic pocket for phospholipid binding. However in vitro lipid transfer assays showed that Mdm12 alone or an Mmm1 (another ERMES subunit) fusion protein exhibited only a weak lipid transfer activity between liposomes. In contrast, Mdm12 in a complex with Mmm1 mediated efficient lipid transfer between liposomes. Mutations in Mmm1 or Mdm12 impaired the lipid transfer activities of the Mdm12-Mmm1 complex and furthermore caused defective phosphatidylserine transport from the ER to mitochondrial membranes via ERMES in vitro. Therefore, the Mmm1-Mdm12 complex functions as a minimal unit that mediates lipid transfer between membranes. © 2018 Kawano et al.

  4. NATURAL MICROFLORA OF WINE GRAPE BERRIES

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    Attila Kántor

    2015-02-01

    Full Text Available The diversity of yeasts and bacterial species on grapes has been investigated in vineyards worldwide. For winemaking are very important three groups of microorganisms. First two includes acetic acid and lactic acid bacteria; they live and grow normally on grape surface. The third group includes more than 20 detectable genera of yeasts. There are three principal genera found on grapes Hanseniaspora uvarum (Kloeckera apiculata, Metschnikowia pulcherrima (Candida pulcherrima, and Candida stellata or new descripted Candida zemplinina. Aim of this study was investigate of number of three major groups of microorganisms which are important for grapes and winemaking. The number of bacteria on Acetobacter agar (AA ranged from 1.76 log CFU/mL to 2.80 log CFU/mL. Lactic acid bacteria were counted on MRS agar and the number of detectable colonies ranged from 0.48 log CFU/mL to 2.06 log CFU/mL. Sabouraud dextrose agar (SDA was used for cultivation of yeast and the number of yeasts ranged from 2.47 log CFU/mL to 2.76 log CFU/mL. For identification of yeast species were used different types of agar media with acid base indicator bromocresol green. Identified 10 yeasts species includes to genus: Candida, Metschnikowia, Pichia, Kluyveromyces, Hanseniaspora, Hansenula, Candida, Debaromyces, Rhodotorula and Saccharomyces. We identified only few bacterial species includes to genus Lactobacillus, Pediococcus, Gluconobacter and Acetobacter.

  5. Spectroscopic studies, antimicrobial activities and crystal structures of N-(2-hydroxy-3-methoxybenzalidene)1-aminonaphthalene

    Science.gov (United States)

    Ünver, Hüseyin; Yıldız, Mustafa; Dülger, Başaran; Özgen, Özen; Kendi, Engin; Durlu, Tahsin Nuri

    2005-03-01

    Schiff base N-(2-hydroxy-3-methoxybenzalidene)1-aminonaphthalene has been synthesized from the reaction of 2-hydroxy-3-methoxybenzaldehyde with 1-aminonaphthalene. The compound were characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR and UV-visible techniques. The UV-visible spectra of the Schiff base were studied in polar and nonpolar solvents in acidic and basic media. The structure of the compound has been examined cyrstallographically. There are two independent molecules in the asymmetric unit. It crystallizes in the monoclinic space group P21/c, with unit cell parameters: a=14, 602(2), b=5,800(1), c=16, 899(1) Å, V=1394.4(2) Å 3, Dx=1.321 g cm -3 and Z=4. The crystal structure was solved by direct methods and refined by full-matrix least squares to a find R=0.041 of for 1179 observed reflections. The title compound's antimicrobial activities also have been studied. The antimicrobial activities of the ligand has been screened in vitro against the organisms Escherichia coli ATCC 11230, Staphylococcus aureus ATCC 6538, Klebsiella pneumoniae UC57, Micrococcus luteus La 2971, Proteus vulgaris ATCC 8427, Pseudomonas aeruginosa ATCC 27853, Mycobacterium smegmatis CCM 2067, Bacillus cereus ATCC 7064 and Listeria monocytogenes ATCC 15313, the yeast cultures Candida albicans ATCC 10231, Kluyveromyces fragilis NRRL 2415, Rhodotorula rubra DSM 70403, Debaryomyces hansenii DSM 70238 and Hanseniaspora guilliermondii DSM 3432.

  6. Yeast "make-accumulate-consume" life strategy evolved as a multi-step process that predates the whole genome duplication.

    Science.gov (United States)

    Hagman, Arne; Säll, Torbjörn; Compagno, Concetta; Piskur, Jure

    2013-01-01

    When fruits ripen, microbial communities start a fierce competition for the freely available fruit sugars. Three yeast lineages, including baker's yeast Saccharomyces cerevisiae, have independently developed the metabolic activity to convert simple sugars into ethanol even under fully aerobic conditions. This fermentation capacity, named Crabtree effect, reduces the cell-biomass production but provides in nature a tool to out-compete other microorganisms. Here, we analyzed over forty Saccharomycetaceae yeasts, covering over 200 million years of the evolutionary history, for their carbon metabolism. The experiments were done under strictly controlled and uniform conditions, which has not been done before. We show that the origin of Crabtree effect in Saccharomycetaceae predates the whole genome duplication and became a settled metabolic trait after the split of the S. cerevisiae and Kluyveromyces lineages, and coincided with the origin of modern fruit bearing plants. Our results suggest that ethanol fermentation evolved progressively, involving several successive molecular events that have gradually remodeled the yeast carbon metabolism. While some of the final evolutionary events, like gene duplications of glucose transporters and glycolytic enzymes, have been deduced, the earliest molecular events initiating Crabtree effect are still to be determined.

  7. Synthetic biology and molecular genetics in non-conventional yeasts: Current tools and future advances.

    Science.gov (United States)

    Wagner, James M; Alper, Hal S

    2016-04-01

    Coupling the tools of synthetic biology with traditional molecular genetic techniques can enable the rapid prototyping and optimization of yeast strains. While the era of yeast synthetic biology began in the well-characterized model organism Saccharomyces cerevisiae, it is swiftly expanding to include non-conventional yeast production systems such as Hansenula polymorpha, Kluyveromyces lactis, Pichia pastoris, and Yarrowia lipolytica. These yeasts already have roles in the manufacture of vaccines, therapeutic proteins, food additives, and biorenewable chemicals, but recent synthetic biology advances have the potential to greatly expand and diversify their impact on biotechnology. In this review, we summarize the development of synthetic biological tools (including promoters and terminators) and enabling molecular genetics approaches that have been applied in these four promising alternative biomanufacturing platforms. An emphasis is placed on synthetic parts and genome editing tools. Finally, we discuss examples of synthetic tools developed in other organisms that can be adapted or optimized for these hosts in the near future. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Recent advances in the genome-wide study of DNA replication origins in yeast

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    Chong ePeng

    2015-02-01

    Full Text Available DNA replication, one of the central events in the cell cycle, is the basis of biological inheritance. In order to be duplicated, a DNA double helix must be opened at defined sites, which are called DNA replication origins (ORIs. Unlike in bacteria, where replication initiates from a single replication origin, multiple origins are utilized in the eukaryotic genome. Among them, the ORIs in budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe have been best characterized. In recent years, advances in DNA microarray and next-generation sequencing technologies have increased the number of yeast species involved in ORIs research dramatically. The ORIs in some nonconventional yeast species such as Kluyveromyces lactis and Pichia pastoris have also been genome-widely identified. Relevant databases of replication origins in yeast were constructed, then the comparative genomic analysis can be carried out. Here, we review several experimental approaches that have been used to map replication origins in yeast and some of the available web resources related to yeast ORIs. We also discuss the sequence characteristics and chromosome structures of ORIs in the four yeast species, which can be utilized to improve the replication origins prediction.

  9. Identification by PCR and evaluation of probiotic potential in yeast strains found in kefir samples in the city of Santa Maria, RS, Brazil

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    Daniela CASSANEGO

    2017-10-01

    Full Text Available Abstract Kefir is a product elaborated from the symbiotic fermentation of different microorganisms. The Kluyveromyces and Saccharomyces genera are the major representatives of the yeasts found in kefir microbiota. The only pobiotic yeast commercialized as an oral medication, is the Saccharomyces boulardii. The present work involved the microbiological quality examination of six kefir samples in the city of Santa Maria/RS, the yeasts isolation present in the samples and the identification of them by PCR (Polymerase chain reaction. Then, their probiotic potential was evaluated by in vitro technique. After that, microbiological analysis confirmed that kefir samples were suitable for consumption once the microbiological quality was established. Nineteen yeast strains were isolated from six different kefir samples; it was identified, by PCR analysis, but only three species were identified from these microorganisms in the present article: Saccharomyces cerevisiae, Hanseniospora uvarum and Kazachstania unispora. Nevertheless, by simulating the passage of isolated strains through the gastrointestinal environment, it was observed that they could not be considered probiotics. The results indicate that, in an isolated way, the yeast presents in kefir samples, in the city of Santa Maria, RS, can´t be considered probiotics according to the tests performed.

  10. Brazilian kefir: structure, microbial communities and chemical composition

    Directory of Open Access Journals (Sweden)

    Karina Teixeira Magalhães

    2011-06-01

    Full Text Available Microbial ecology and chemical composition of Brazilian kefir beverage was performed. The microorganisms associated with Brazilian kefir were investigated using a combination of phenotypic and genotypic methods. A total of 359 microbial isolates were identified. Lactic acid bacteria (60.5% were the major isolated group identified, followed by yeasts (30.6% and acetic acid bacteria (8.9%. Lactobacillus paracasei (89 isolates, Lactobacillus parabuchneri (41 isolates, Lactobacillus casei (32 isolates, Lactobacillus kefiri (31 isolates, Lactococcus lactis (24 isolates, Acetobacter lovaniensis (32 isolates, Kluyveromyces lactis (31 isolates, Kazachstania aerobia (23 isolates, Saccharomyces cerevisiae (41 isolates and Lachancea meyersii (15 isolates were the microbial species isolated. Scanning electron microscopy showed that the microbiota was dominated by bacilli (short and curved long cells growing in close association with lemon-shaped yeasts cells. During the 24 h of fermentation, the protein content increased, while lactose and fat content decreased. The concentration of lactic acid ranged from 1.4 to 17.4 mg/ml, and that of acetic acid increased from 2.1 to 2.73 mg/ml. The production of ethanol was limited, reaching a final mean value of 0.5 mg/ml.

  11. Microbiological, biochemical, and functional aspects of sugary kefir fermentation - A review.

    Science.gov (United States)

    Fiorda, Fernanda Assumpção; de Melo Pereira, Gilberto Vinicius; Thomaz-Soccol, Vanete; Rakshit, Sudip Kumar; Pagnoncelli, Maria Giovana Binder; Vandenberghe, Luciana Porto de Souza; Soccol, Carlos Ricardo

    2017-09-01

    Sugary kefir beverage is produce by fermenting raw sugar solution with kefir grains, the latter consisting of polysaccharide and microorganisms. This beverage, with great consumption in countries such as USA, Japan, France, and Brazil, represents a promising market to functional cultured drinks. This paper reviews the microbial diversity and interaction, kinetics, safety, and bioactivities of sugary kefir fermentation. The literature reviewed here demonstrates that sugary kefir possesses a similar microbial association relative to traditional milk kefir fermentation, especially among lactic acid bacteria and yeast species, such as Lactobacillus, Leuconostoc, Kluyveromyces, Pichia, and Saccharomyces. However, a selective pressure at species level is generally observed, as, for example, the stimulation of Saccharomyces species metabolism, leading to a high content of alcohol in the final product. This also seems to stimulate the growth of acetic acid bacteria that benefit of increased ethanol production to acetic acid metabolism. Existing reports have suggested important bioactivities associated with sugary kefir beverage consumption, such as antimicrobial, antiedematogenic, anti-inflammatory, antioxidant, cicatrizing, and healing activities. Other alternative non-dairy substrates, such as fruits, vegetables, and molasses, have also been tested for adaptation of kefir grains and production of functional beverages with distinct sensory characteristics. This diversification is of crucial importance for the production of new probiotic products to provide people with special needs (lactose intolerance) and vegan consumers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Synthetic Biology and Metabolic Engineering Approaches and Its Impact on Non-Conventional Yeast and Biofuel Production

    Energy Technology Data Exchange (ETDEWEB)

    Madhavan, Aravind [Biotechnology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Trivandrum (India); Rajiv Gandhi Centre for Biotechnology, Trivandrum (India); Jose, Anju Alphonsa; Binod, Parameswaran; Sindhu, Raveendran, E-mail: sindhurgcb@gmail.com; Sukumaran, Rajeev K. [Biotechnology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Trivandrum (India); Pandey, Ashok [Biotechnology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Trivandrum (India); Center for Innovative and Applied Bioprocessing, Mohali, Punjab (India); Castro, Galliano Eulogio [Dpt. Ingeniería Química, Ambiental y de los Materiales Edificio, Universidad de Jaén, Jaén (Spain)

    2017-04-25

    The increasing fossil fuel scarcity has led to an urgent need to develop alternative fuels. Currently microorganisms have been extensively used for the production of first-generation biofuels from lignocellulosic biomass. Yeast is the efficient producer of bioethanol among all existing biofuels option. Tools of synthetic biology have revolutionized the field of microbial cell factories especially in the case of ethanol and fatty acid production. Most of the synthetic biology tools have been developed for the industrial workhorse Saccharomyces cerevisiae. The non-conventional yeast systems have several beneficial traits like ethanol tolerance, thermotolerance, inhibitor tolerance, genetic diversity, etc., and synthetic biology have the power to expand these traits. Currently, synthetic biology is slowly widening to the non-conventional yeasts like Hansenula polymorpha, Kluyveromyces lactis, Pichia pastoris, and Yarrowia lipolytica. Herein, we review the basic synthetic biology tools that can apply to non-conventional yeasts. Furthermore, we discuss the recent advances employed to develop efficient biofuel-producing non-conventional yeast strains by metabolic engineering and synthetic biology with recent examples. Looking forward, future synthetic engineering tools’ development and application should focus on unexplored non-conventional yeast species.

  13. Vicilin-like peptides from Capsicum baccatum L. seeds are α-amylase inhibitors and exhibit antifungal activity against important yeasts in medical mycology.

    Science.gov (United States)

    Vieira Bard, Gabriela C; Nascimento, Viviane V; Oliveira, Antônia Elenir A; Rodrigues, Rosana; Da Cunha, Maura; Dias, Germana B; Vasconcelos, Ilka M; Carvalho, Andre O; Gomes, Valdirene M

    2014-07-01

    The objective of this study was to isolate antimicrobial peptides from Capsicum baccatum seeds and evaluate their antimicrobial activity and inhibitory effects against α-amylase. Initially, proteins from the flour of C. baccatum seeds were extracted in sodium phosphate buffer, pH 5.4, and precipitated with ammonium sulfate at 90% saturation. The D1 and D2 fractions were subjected to antifungal tests against the yeasts Saccharomyces cerevisiae, Candida albicans, Candida tropicalis, and Kluyveromyces marxiannus, and tested against α-amylases from Callosobruchus maculates and human saliva. The D2 fraction presented higher antimicrobial activity and was subjected to further purification and seven new different fractions (H1-H7) were obtained. Peptides in the H4 fraction were sequenced and the N-terminal sequences revealed homology with previously reported storage vicilins from seeds. The H4 fraction exhibited strong antifungal activity and also promoted morphological changes in yeast, including pseudohyphae formation. All fractions, including H4, inhibited mammalian α-amylase activity but only the H4 fraction was able to inhibit C. maculatus α-amylase activity. These results suggest that the fractions isolated from the seeds of C. baccatum can act directly in plant defenses against pathogens and insects. © 2014 Wiley Periodicals, Inc.

  14. Alcohol production by selected yeast strains in lactase-hydrolyzed acid whey

    Energy Technology Data Exchange (ETDEWEB)

    O' Leary, V S; Green, R; Sullivan, B C; Holsinger, V H

    1977-07-01

    Ethanol production by Kluyveromyces fragilis and Saccharomyces cerevisiae was studied using cottage cheese whey in which 80 to 90 percent of the lactose present had been prehydrolyzed to glucose and galactose. Complete fermentation of the sugar by K. fragilis required 120 hr at 30/sup 0/C in lactase-hydrolyzed whey compared to 72 hr in nonhydrolyzed whey. This effect was due to a diauxic fermentation pattern in lactase-hydrolyzed whey with glucose being fermented before galactose. Ethanol yields of about 2 percent were obtained in both types of whey when K. fragilis was the organism used for fermentation. Saccharomyces cerevisiae produced alcohol from glucose more rapidly than K. fragilis, but galactose was fermented only when S. cerevisiae was pregrown on galactose. Slightly lower alcohol yields were obtained with S. cerevisiae, owing to the presence of some lactose in the whey which was not fermented by this organism. Although prehydrolysis of lactose in whey and whey fractions is advantageous in that microbial species unable to ferment lactose may be utilized, diauxic and galactose utilization problems must be considered.

  15. Enzymatic hydrolysis of lactose of whey permeate

    Directory of Open Access Journals (Sweden)

    Karina Nascimento de Almeida

    2015-09-01

    Full Text Available The whey permeate is the residual of the concentration process of the whey proteins by ultrafiltration method. It contains important nutrients such as lactose, minerals and some proteins and lipids. It is without an ending industrial waste that causes serious damage to the environment. For its full use the lactose must be hydrolyzed to enable its consumption by intolerant people. The enzymatic hydrolysis by lactase (β-galactosidase of Kluyveromyces lactis yeast is a safe method that does not compromise the integrity of other nutrients, enabling further use of the permeate as a raw material. This study aimed to perform tests of enzymatic hydrolysis of lactose in whey permeate formulations in a concentration of 0.2%, 0.7% and 1% at 30, 60 and 90 minutes with pH 6.3 medium and 37 °C. The reactions were monitored by high performance liquid chromatography which showed that the enzyme concentration of 0.7% at time 30 minutes formulations became safe for consumption by lactose intolerant people, according to minimum levels established by law.

  16. Lactose Hydrolysis in Milk and Dairy Whey Using Microbial β-Galactosidases

    Directory of Open Access Journals (Sweden)

    Michele Dutra Rosolen

    2015-01-01

    Full Text Available This work aimed at evaluating the influence of enzyme concentration, temperature, and reaction time in the lactose hydrolysis process in milk, cheese whey, and whey permeate, using two commercial β-galactosidases of microbial origins. We used Aspergillus oryzae (at temperatures of 10 and 55°C and Kluyveromyces lactis (at temperatures of 10 and 37°C β-galactosidases, both in 3, 6, and 9 U/mL concentrations. In the temperature of 10°C, the K. lactis β-galactosidase enzyme is more efficient in the milk, cheese whey, and whey permeate lactose hydrolysis when compared to A. oryzae. However, in the enzyme reaction time and concentration conditions evaluated, 100% lactose hydrolysis was not reached using the K. lactis β-galactosidase. The total lactose hydrolysis in whey and permeate was obtained with the A. oryzae enzyme, when using its optimum temperature (55°C, at the end of a 12 h reaction, regardless of the enzyme concentration used. For the lactose present in milk, this result occurred in the concentrations of 6 and 9 U/mL, with the same time and temperature conditions. The studied parameters in the lactose enzymatic hydrolysis are critical for enabling the application of β-galactosidases in the food industry.

  17. Influence of lactose hydrolysis and solids concentration on alcohol production by yeast in acid whey ultrafiltrate

    Energy Technology Data Exchange (ETDEWEB)

    O' leary, V S; Sutton, C; Bencivengo, M; Sullivan, B; Holsinger, V H

    1977-11-01

    Alcohol yields of 6.5 percent were obtained with Saccharomyces cerevisiae in lactase-hydrolyzed acid whey permeate containing 30 to 35 percent total solids. Maximum alcohol yields obtained with Kluyveromyces fragilis were 4.5 percent in lactase-hydrolyzed acid whey permeate at a solids concentration of 20 percent and 3.7 percent in normal permeate at a solids concentration of 10 percent. Saccharomyces cerevisiae efficiently converted the glucose present in lactase-hydrolyzed whey permeates containing 5 to 30 percent total solids (2 to 13 percent glucose) to alcohol. However, the galactose, which comprised about half the available carbohydrate in lactase-hydrolyzed whey, was not utilized by S. cerevisiae, so that even though alcohol yields were higher when this organism was used, the process was wasteful in that a substantial proportion of the substrate was not fermented. For the process to become commercially feasible, an efficient means of rapidly converting both the galactose and glucose to alcohol must be found.

  18. An Effective Big Data Supervised Imbalanced Classification Approach for Ortholog Detection in Related Yeast Species

    Directory of Open Access Journals (Sweden)

    Deborah Galpert

    2015-01-01

    Full Text Available Orthology detection requires more effective scaling algorithms. In this paper, a set of gene pair features based on similarity measures (alignment scores, sequence length, gene membership to conserved regions, and physicochemical profiles are combined in a supervised pairwise ortholog detection approach to improve effectiveness considering low ortholog ratios in relation to the possible pairwise comparison between two genomes. In this scenario, big data supervised classifiers managing imbalance between ortholog and nonortholog pair classes allow for an effective scaling solution built from two genomes and extended to other genome pairs. The supervised approach was compared with RBH, RSD, and OMA algorithms by using the following yeast genome pairs: Saccharomyces cerevisiae-Kluyveromyces lactis, Saccharomyces cerevisiae-Candida glabrata, and Saccharomyces cerevisiae-Schizosaccharomyces pombe as benchmark datasets. Because of the large amount of imbalanced data, the building and testing of the supervised model were only possible by using big data supervised classifiers managing imbalance. Evaluation metrics taking low ortholog ratios into account were applied. From the effectiveness perspective, MapReduce Random Oversampling combined with Spark SVM outperformed RBH, RSD, and OMA, probably because of the consideration of gene pair features beyond alignment similarities combined with the advances in big data supervised classification.

  19. Hydrolysis of inulin from Jerusalem artichoke by inulinase immobilized on aminoethylcellulose

    Energy Technology Data Exchange (ETDEWEB)

    Kim, W.Y.; Byun, S.M.; Uhm, T.B.

    1982-01-01

    Purified inulinase (I, EC 3.2.1.7) of Kluyveromyces fragilis was immobilized on 2-aminoethylcellulose by treatment with 2% glutaraldehyde in 0.05M phosphate buffer, pH 7.0, for 2 hours at room temperature. The immobilized enzyme preparation had 39.3 units I activity/dried matrix, with 53.4% recovery yield of activity, and showed good operational stability in the presence of substrate, inulin or the tuber extract of Jerusalem artichoke. Optimum pH and temperature were 5.5 and 45 degrees, respectively. In a batch reactor, the conversion was 90% (D-fructose/D-glucose = 76/24) and 34 mg D-fructose/mL was produced from the artichoke tuber extract by the immobilized I in 20 hours. In column reactor packed with 28 mL immobilized I, the following conditions were optimal: height/diameter ratio of column 10.3 space time 3.8 hours temperature 40 degrees. Operation under these conditions gave 90% conversion of a 7% inulin solution and the productivity was 102 mmol/L/h.

  20. Replisome stall events have shaped the distribution of replication origins in the genomes of yeasts

    Science.gov (United States)

    Newman, Timothy J.; Mamun, Mohammed A.; Nieduszynski, Conrad A.; Blow, J. Julian

    2013-01-01

    During S phase, the entire genome must be precisely duplicated, with no sections of DNA left unreplicated. Here, we develop a simple mathematical model to describe the probability of replication failing due to the irreversible stalling of replication forks. We show that the probability of complete genome replication is maximized if replication origins are evenly spaced, the largest inter-origin distances are minimized, and the end-most origins are positioned close to chromosome ends. We show that origin positions in the yeast Saccharomyces cerevisiae genome conform to all three predictions thereby maximizing the probability of complete replication if replication forks stall. Origin positions in four other yeasts—Kluyveromyces lactis, Lachancea kluyveri, Lachancea waltii and Schizosaccharomyces pombe—also conform to these predictions. Equating failure rates at chromosome ends with those in chromosome interiors gives a mean per nucleotide fork stall rate of ∼5 × 10−8, which is consistent with experimental estimates. Using this value in our theoretical predictions gives replication failure rates that are consistent with data from replication origin knockout experiments. Our theory also predicts that significantly larger genomes, such as those of mammals, will experience a much greater probability of replication failure genome-wide, and therefore will likely require additional compensatory mechanisms. PMID:23963700

  1. Recent advances in the genome-wide study of DNA replication origins in yeast

    Science.gov (United States)

    Peng, Chong; Luo, Hao; Zhang, Xi; Gao, Feng

    2015-01-01

    DNA replication, one of the central events in the cell cycle, is the basis of biological inheritance. In order to be duplicated, a DNA double helix must be opened at defined sites, which are called DNA replication origins (ORIs). Unlike in bacteria, where replication initiates from a single replication origin, multiple origins are utilized in the eukaryotic genomes. Among them, the ORIs in budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe have been best characterized. In recent years, advances in DNA microarray and next-generation sequencing technologies have increased the number of yeast species involved in ORIs research dramatically. The ORIs in some non-conventional yeast species such as Kluyveromyces lactis and Pichia pastoris have also been genome-widely identified. Relevant databases of replication origins in yeast were constructed, then the comparative genomic analysis can be carried out. Here, we review several experimental approaches that have been used to map replication origins in yeast and some of the available web resources related to yeast ORIs. We also discuss the sequence characteristics and chromosome structures of ORIs in the four yeast species, which can be utilized to improve yeast replication origins prediction. PMID:25745419

  2. Structure-based nuclear import mechanism of histones H3 and H4 mediated by Kap123

    Energy Technology Data Exchange (ETDEWEB)

    An, Sojin [Department of Biological Chemistry, University of Michigan Medical School, Michigan, United States; Yoon, Jungmin [Structural Biology Laboratory of Epigenetics, Department of Biological Sciences, Graduate school of Nanoscience and Technology (World Class University), KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, South Korea; Kim, Hanseong [Department of Biological Chemistry, University of Michigan Medical School, Michigan, United States; Song, Ji-Joon [Structural Biology Laboratory of Epigenetics, Department of Biological Sciences, Graduate school of Nanoscience and Technology (World Class University), KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon, South Korea; Cho, Uhn-soo [Department of Biological Chemistry, University of Michigan Medical School, Michigan, United States

    2017-10-16

    Kap123, a major karyopherin protein of budding yeast, recognizes the nuclear localization signals (NLSs) of cytoplasmic histones H3 and H4 and translocates them into the nucleus during DNA replication. Mechanistic questions include H3- and H4-NLS redundancy toward Kap123 and the role of the conserved diacetylation of cytoplasmic H4 (K5ac and K12ac) in Kap123-mediated histone nuclear translocation. Here, we report crystal structures of full-length Kluyveromyces lactis Kap123 alone and in complex with H3- and H4-NLSs. Structures reveal the unique feature of Kap123 that possesses two discrete lysine-binding pockets for NLS recognition. Structural comparison illustrates that H3- and H4-NLSs share at least one of two lysine-binding pockets, suggesting that H3- and H4-NLSs are mutually exclusive. Additionally, acetylation of key lysine residues at NLS, particularly H4-NLS diacetylation, weakens the interaction with Kap123. These data support that cytoplasmic histone H4 diacetylation weakens the Kap123-H4-NLS interaction thereby facilitating histone Kap123-H3-dependent H3:H4/Asf1 complex nuclear translocation.

  3. A differential medium for the enumeration of the spoilage yeast Zygosaccharomyces bailii in wine.

    Science.gov (United States)

    Schuller, D; Côrte-Real, M; Leão, C

    2000-11-01

    A collection of yeasts, isolated mostly from spoiled wines, was used in order to develop a differential medium for Zygosaccharomyces bailii. The 118 selected strains of 21 species differed in their origin and resistance to preservatives and belonged to the genera Pichia, Torulaspora, Dekkera, Debaryomyces, Saccharomycodes, Issatchenkia, Kluyveromyces, Kloeckera, Lodderomyces, Schizosaccharomyces, Rhodotorula, Saccharomyces, and Zygosaccharomyces. The design of the culture medium was based on the different ability of the various yeast species to grow in a mineral medium with glucose and formic acid (mixed-substrate medium) as the only carbon and energy sources and supplemented with an acid-base indicator. By manipulating the concentration of the acid and the sugar it was possible to select conditions where only Z. bailii strains gave rise to alkalinization, associated with a color change of the medium (positive response). The final composition of the mixed medium was adjusted as a compromise between the percentage of recovery and selectivity for Z. bailii. This was accomplished by the use of pure or mixed cultures of the yeast strains and applying the membrane filtration methodology. The microbiological analysis of two samples of contaminated Vinho Verde showed that the new medium can be considered as a differential medium to distinguish Z. bailii from other contaminating yeasts, having potential application in the microbiological control of wines and probably other beverages and foods.

  4. The binary response of the GAL/MEL genetic switch of Saccharomyces cerevisiae is critically dependent on Gal80p-Gal4p interaction.

    Science.gov (United States)

    Das Adhikari, Akshay Kumar; Bhat, Paike Jayadeva

    2016-09-01

    Studies on the Saccharomyces cerevisiae GAL/MEL genetic switch have revealed that its bistability is dependent on ultrasensitivity that can be altered or abolished by disabling different combinations of nested feedback loops. In contrast, we have previously demonstrated that weakening of the interaction between Gal80p and Gal4p alone is sufficient to abolish the ultrasensitivity (Das Adhikari et al. 2014). Here, we demonstrate that altering the epistatic interaction between Gal80p and Gal4p also abolishes the bistability, and the switch response to galactose becomes graded instead of binary. However, the GAL/MEL switch of wild-type and epistatically altered strains responded in a graded fashion to melibiose. The properties of the epistatically altered strain resemble Kluyveromyces lactis, which separated from the Saccharomyces lineage 100 mya before whole-genome duplication (WGD). Based on the results reported here, we propose that epistatic interactions played a crucial role in the evolution of the fine regulation of S. cerevisiae GAL/MEL switch following WGD. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Kamboçya Çayından İzole Edilen Mayaların Antimikrobiyal Aktivitelerinin İncelenmesi

    Directory of Open Access Journals (Sweden)

    Sibel Şafak

    2015-02-01

    Full Text Available Bu araştırmada, Kombucha çayından 15 adet maya izole edilmiştir. İdentifikasyon sonuçlan bunların Saccharomyces cerevisiae (8, Candida krusei (2, Kloeckera apiculata (2 ve Kluyveromyces africanus (1 olduğunu göstermiştir. Mayaların genel inhibisyon etkileri bazı kontaminant ve patojen bakteriler (Escherichia coli, Staphylococcus aureus, Pseudomonas aeroginosa ve Yersinia enterocolitica üzerinde ağar diffüzyon yöntemi ile belirlenmiştir. Araştırma sonuçları, mayaların S. aureus üzerinde değişik oranlarda inhibisyon etkilerinin olduğunu göstermiştir. Mayaların diğer test bakteriler üzerinde antimikrobiyal etki göstermedikleri tespit edilmiştir.

  6. Production of fuel ethanol from molasses by thermotolerant yeast

    International Nuclear Information System (INIS)

    Hamad, S. H.

    2009-01-01

    A thermotolerant strain of the yeast Kluyveromyces marxians, isolated from Kenana sugar factory in the Sudan, was used for the production of ethanol from molasses. Fermentations were carried out in a bioreactor with 10-litre working volume at three temperatures and three sugar concentrations in batch and at one temperature and three feeding rates in fed-batch processes. In the batch fermentations, the best results were obtained at 40 o C and 20% sugar, where a maximum of 9.2% (w/v) ethanol concentration was produced in 30 hours with a yield of 90% of the theoretical and a maximum ethanol specific productivity of 0.65 g per gramme yeast and hour. In the fed-batch process at 40 o C , the best results were obtained at 0.5 1/h feeding rate of a substrate with 400 g/1 sugar. Under such conditions, the yeast produced up to 9.34% (w/v) ethanol with 91.6% of the theoretical yield in 14 hours of fermentation and a maximum specific ethanol productivity of 0.9 g per gramme yeast and hour. (Author)

  7. Determination of antioxidant and antimicrobial properties of Eremurus spectabilis Bieb.

    Directory of Open Access Journals (Sweden)

    Burak Bircan

    2015-11-01

    Full Text Available In this study, in vitro antioxidant and antimicrobial activities of the E. spectabilis Bieb., which is consumed as a vegetable among people, was investigated and Kluyveromyces lactis’s antioxidant activies in anaerobic cultural environment is researched. This purpose; 2,2-diphenyl-1-picrylhydrazyl (DPPH radical scavenging activity, flavonoid, resveratrol, sugar contents, lipid peroxidation (LPO levels, fatty acid level, lipophilic vitamin values, protein and glutathione amounts were measured. In the FeCl group in which FeCl2+ H2O2 is applied, when compared with LPO level control group (K, it was observed that it increase in high amount (p<0.05. LPO level decreases in certain proportions in treatment groups. It is suggested that the lowering effect of the LPO of E. spectabilis extracts are arise from phytochemical like flavonoids that it includes. As a result of the antibacterial activity studies, it was observed that E. spectabilis have different proportional antimicrobial activities against E. coli, S. aureus, Epidermophyton spp. and C. albicans.

  8. Synthetic Biology and Metabolic Engineering Approaches and Its Impact on Non-Conventional Yeast and Biofuel Production

    Directory of Open Access Journals (Sweden)

    Raveendran Sindhu

    2017-04-01

    Full Text Available The increasing fossil fuel scarcity has led to an urgent need to develop alternative fuels. Currently microorganisms have been extensively used for the production of first-generation biofuels from lignocellulosic biomass. Yeast is the efficient producer of bioethanol among all existing biofuels option. Tools of synthetic biology have revolutionized the field of microbial cell factories especially in the case of ethanol and fatty acid production. Most of the synthetic biology tools have been developed for the industrial workhorse Saccharomyces cerevisiae. The non-conventional yeast systems have several beneficial traits like ethanol tolerance, thermotolerance, inhibitor tolerance, genetic diversity, etc., and synthetic biology have the power to expand these traits. Currently, synthetic biology is slowly widening to the non-conventional yeasts like Hansenula polymorpha, Kluyveromyces lactis, Pichia pastoris, and Yarrowia lipolytica. Herein, we review the basic synthetic biology tools that can apply to non-conventional yeasts. Furthermore, we discuss the recent advances employed to develop efficient biofuel-producing non-conventional yeast strains by metabolic engineering and synthetic biology with recent examples. Looking forward, future synthetic engineering tools’ development and application should focus on unexplored non-conventional yeast species.

  9. Phenylpropanoid Glycoside Analogues: Enzymatic Synthesis, Antioxidant Activity and Theoretical Study of Their Free Radical Scavenger Mechanism

    Science.gov (United States)

    López-Munguía, Agustín; Hernández-Romero, Yanet; Pedraza-Chaverri, José; Miranda-Molina, Alfonso; Regla, Ignacio; Martínez, Ana; Castillo, Edmundo

    2011-01-01

    Phenylpropanoid glycosides (PPGs) are natural compounds present in several medicinal plants that have high antioxidant power and diverse biological activities. Because of their low content in plants (less than 5% w/w), several chemical synthetic routes to produce PPGs have been developed, but their synthesis is a time consuming process and the achieved yields are often low. In this study, an alternative and efficient two-step biosynthetic route to obtain natural PPG analogues is reported for the first time. Two galactosides were initially synthesized from vanillyl alcohol and homovanillyl alcohol by a transgalactosylation reaction catalyzed by Kluyveromyces lactis β-galactosidase in saturated lactose solutions with a 30%–35% yield. To synthesize PPGs, the galactoconjugates were esterified with saturated and unsaturated hydroxycinnamic acid derivatives using Candida antarctica Lipase B (CaL-B) as a biocatalyst with 40%–60% yields. The scavenging ability of the phenolic raw materials, intermediates and PPGs was evaluated by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) method. It was found that the biosynthesized PPGs had higher scavenging abilities when compared to ascorbic acid, the reference compound, while their antioxidant activities were found similar to that of natural PPGs. Moreover, density functional theory (DFT) calculations were used to determine that the PPGs antioxidant mechanism proceeds through a sequential proton loss single electron transfer (SPLET). The enzymatic process reported in this study is an efficient and versatile route to obtain PPGs from different phenylpropanoid acids, sugars and phenolic alcohols. PMID:21674039

  10. Autoselection of cytoplasmic yeast virus like elements encoding toxin/antitoxin systems involves a nuclear barrier for immunity gene expression.

    Science.gov (United States)

    Kast, Alene; Voges, Raphael; Schroth, Michael; Schaffrath, Raffael; Klassen, Roland; Meinhardt, Friedhelm

    2015-05-01

    Cytoplasmic virus like elements (VLEs) from Kluyveromyces lactis (Kl), Pichia acaciae (Pa) and Debaryomyces robertsiae (Dr) are extremely A/T-rich (>75%) and encode toxic anticodon nucleases (ACNases) along with specific immunity proteins. Here we show that nuclear, not cytoplasmic expression of either immunity gene (PaORF4, KlORF3 or DrORF5) results in transcript fragmentation and is insufficient to establish immunity to the cognate ACNase. Since rapid amplification of 3' ends (RACE) as well as linker ligation of immunity transcripts expressed in the nucleus revealed polyadenylation to occur along with fragmentation, ORF-internal poly(A) site cleavage due to the high A/T content is likely to prevent functional expression of the immunity genes. Consistently, lowering the A/T content of PaORF4 to 55% and KlORF3 to 46% by gene synthesis entirely prevented transcript cleavage and permitted functional nuclear expression leading to full immunity against the respective ACNase toxin. Consistent with a specific adaptation of the immunity proteins to the cognate ACNases, cross-immunity to non-cognate ACNases is neither conferred by PaOrf4 nor KlOrf3. Thus, the high A/T content of cytoplasmic VLEs minimizes the potential of functional nuclear recruitment of VLE encoded genes, in particular those involved in autoselection of the VLEs via a toxin/antitoxin principle.

  11. Autoselection of cytoplasmic yeast virus like elements encoding toxin/antitoxin systems involves a nuclear barrier for immunity gene expression.

    Directory of Open Access Journals (Sweden)

    Alene Kast

    2015-05-01

    Full Text Available Cytoplasmic virus like elements (VLEs from Kluyveromyces lactis (Kl, Pichia acaciae (Pa and Debaryomyces robertsiae (Dr are extremely A/T-rich (>75% and encode toxic anticodon nucleases (ACNases along with specific immunity proteins. Here we show that nuclear, not cytoplasmic expression of either immunity gene (PaORF4, KlORF3 or DrORF5 results in transcript fragmentation and is insufficient to establish immunity to the cognate ACNase. Since rapid amplification of 3' ends (RACE as well as linker ligation of immunity transcripts expressed in the nucleus revealed polyadenylation to occur along with fragmentation, ORF-internal poly(A site cleavage due to the high A/T content is likely to prevent functional expression of the immunity genes. Consistently, lowering the A/T content of PaORF4 to 55% and KlORF3 to 46% by gene synthesis entirely prevented transcript cleavage and permitted functional nuclear expression leading to full immunity against the respective ACNase toxin. Consistent with a specific adaptation of the immunity proteins to the cognate ACNases, cross-immunity to non-cognate ACNases is neither conferred by PaOrf4 nor KlOrf3. Thus, the high A/T content of cytoplasmic VLEs minimizes the potential of functional nuclear recruitment of VLE encoded genes, in particular those involved in autoselection of the VLEs via a toxin/antitoxin principle.

  12. Controlled production of camembert-type cheeses: part III role of the ripening microflora on free fatty acid concentrations.

    Science.gov (United States)

    Leclercq-Perlat, Marie-Noëlle; Corrieu, Georges; Spinnler, Henry-Eric

    2007-05-01

    Phenomena generating FFAs, important flavour precursors, are significant in cheese ripening. In Camembert-like cheeses, it was intended to establish the relationships between the dynamics of FFA concentrations changes and the succession of ripening microflora during ripening. Experimental Camembert-type cheeses were prepared in duplicate from pasteurised milk inoculated with Kluyveromyces lactis, Geotrichum candidum, Penicillium camemberti, and Brevibacterium aurantiacum under aseptic conditions. For each cheese and each cheesy medium, concentrations of FFAs with odd-numbered carbons, except for 9:0 and 13:0, did not change over time. For long-chain FFAs, concentrations varied with the given cheese part (rind or core). K. lactis produced only short or medium-chain FFAs during its growth and had a minor influence on caproic, caprylic, capric, and lauric acids in comparison with G. candidum, the most lipolytic of the strains used here. It generated all short or medium-chain FFAs (4:0-12:0) during its exponential and slowdown growth periods and only long-chain ones (14:0-18:0) during its stationary phase. Pen. camemberti produced more long-chain FFAs (14:0-18:0) during its sporulation. Brev. aurantiacum did not generate any FFAs. The evidence of links between specific FFAs and the growth of a given microorganism is shown.

  13. The composition of Camembert cheese-ripening cultures modulates both mycelial growth and appearance.

    Science.gov (United States)

    Lessard, Marie-Hélène; Bélanger, Gaétan; St-Gelais, Daniel; Labrie, Steve

    2012-03-01

    The fungal microbiota of bloomy-rind cheeses, such as Camembert, forms a complex ecosystem that has not been well studied, and its monitoring during the ripening period remains a challenge. One limitation of enumerating yeasts and molds on traditional agar media is that hyphae are multicellular structures, and colonies on a petri dish rarely develop from single cells. In addition, fungi tend to rapidly invade agar surfaces, covering small yeast colonies and resulting in an underestimation of their number. In this study, we developed a real-time quantitative PCR (qPCR) method using TaqMan probes to quantify a mixed fungal community containing the most common dairy yeasts and molds: Penicillium camemberti, Geotrichum candidum, Debaryomyces hansenii, and Kluyveromyces lactis on soft-cheese model curds (SCMC). The qPCR method was optimized and validated on pure cultures and used to evaluate the growth dynamics of a ripening culture containing P. camemberti, G. candidum, and K. lactis on the surface of the SCMC during a 31-day ripening period. The results showed that P. camemberti and G. candidum quickly dominated the ecosystem, while K. lactis remained less abundant. When added to this ecosystem, D. hansenii completely inhibited the growth of K. lactis in addition to reducing the growth of the other fungi. This result was confirmed by the decrease in the mycelium biomass on SCMC. This study compares culture-dependent and qPCR methods to successfully quantify complex fungal microbiota on a model curd simulating Camembert-type cheese.

  14. Selection of non-Saccharomyces yeast strains for reducing alcohol levels in wine by sugar respiration.

    Science.gov (United States)

    Quirós, Manuel; Rojas, Virginia; Gonzalez, Ramon; Morales, Pilar

    2014-07-02

    Respiration of sugars by non-Saccharomyces yeasts has been recently proposed for lowering alcohol levels in wine. Development of industrial fermentation processes based on such an approach requires, amongst other steps, the identification of yeast strains which are able to grow and respire under the relatively harsh conditions found in grape must. This work describes the characterization of a collection of non-Saccharomyces yeast strains in order to identify candidate yeast strains for this specific application. It involved the estimation of respiratory quotient (RQ) values under aerated conditions, at low pH and high sugar concentrations, calculation of yields of ethanol and other relevant metabolites, and characterization of growth responses to the main stress factors found during the first stages of alcoholic fermentation. Physiological features of some strains of Metschnikowia pulcherrima or two species of Kluyveromyces, suggest they are suitable for lowering ethanol yields by respiration. The unsuitability of Saccharomyces cerevisiae strains for this purpose was not due to ethanol yields (under aerated conditions they are low enough for a significant reduction in final ethanol content), but to the high acetic acid yields under these growth conditions. According to results from controlled aeration fermentations with one strain of M. pulcherrima, design of an aeration regime allowing for lowering ethanol yields though preserving grape must components from excessive oxidation, would be conceivable. Copyright © 2014. Published by Elsevier B.V.

  15. Respiration-dependent utilization of sugars in yeasts: a determinant role for sugar transporters.

    Science.gov (United States)

    Goffrini, Paola; Ferrero, Iliana; Donnini, Claudia

    2002-01-01

    In many yeast species, including Kluyveromyces lactis, growth on certain sugars (such as galactose, raffinose, and maltose) occurs only under respiratory conditions. If respiration is blocked by inhibitors, mutation, or anaerobiosis, growth does not take place. This apparent dependence on respiration for the utilization of certain sugars has often been suspected to be associated with the mechanism of the sugar uptake step. We hypothesized that in many yeast species, the permease activities for these sugars are not sufficient to ensure the high substrate flow that is necessary for fermentative growth. By introducing additional sugar permease genes, we have obtained K. lactis strains that were capable of growing on galactose and raffinose in the absence of respiration. High dosages of both the permease and maltase genes were indeed necessary for K. lactis cells to grow on maltose in the absence of respiration. These results strongly suggest that the sugar uptake step is the major bottleneck in the fermentative assimilation of certain sugars in K. lactis and probably in many other yeasts.

  16. Potential benefits of the application of yeast starters in table olive processing

    Directory of Open Access Journals (Sweden)

    Francisco Noé eArroyo López

    2012-04-01

    Full Text Available Yeasts play an important role in the food and beverage industry, especially in products such as bread, wine, and beer, among many others. However, their use as a starter in table olive processing has not yet been studied in detail. The candidate yeast strains should be able to dominate fermentation, together with lactic acid bacteria, but should also provide a number of beneficial advantages. Technologically, yeasts should resist low pH and high salt concentrations, produce desirable aromas, improve lactic acid bacteria growth and inhibit spoilage microorganisms. Nowadays, they are being considered as probiotic agents because many species are able to resist the passage through the gastrointestinal tract and show favourable effects on the host. In this way, yeasts may improve the health of consumers by means of the degradation of non assimilated compounds (such as phytate complexes, a decrease in cholesterol levels, the production of vitamins and antioxidants, the inhibition of pathogens, an adhesion to intestinal cell line Caco-2 and the maintenance of epithelial barrier integrity. Many yeast species, usually found in table olive processing (Wicherhamomyces anomalus, Saccharomyces cerevisiae, Pichia membranifaciens, Kluyveromyces lactis, among others, have exhibited some of these properties. Thus, the selection of the most appropriate strains to be used as starters in this fermented vegetable, alone or in combination with lactic acid bacteria, is a promising research line to develop in the near future.

  17. The evolution of Lachancea thermotolerans is driven by geographical determination, anthropisation and flux between different ecosystems.

    Directory of Open Access Journals (Sweden)

    Ana Hranilovic

    Full Text Available The yeast Lachancea thermotolerans (formerly Kluyveromyces thermotolerans is a species with remarkable, yet underexplored, biotechnological potential. This ubiquist occupies a range of natural and anthropic habitats covering a wide geographic span. To gain an insight into L. thermotolerans population diversity and structure, 172 isolates sourced from diverse habitats worldwide were analysed using a set of 14 microsatellite markers. The resultant clustering revealed that the evolution of L. thermotolerans has been driven by the geography and ecological niche of the isolation sources. Isolates originating from anthropic environments, in particular grapes and wine, were genetically close, thus suggesting domestication events within the species. The observed clustering was further validated by several means including, population structure analysis, F-statistics, Mantel's test and the analysis of molecular variance (AMOVA. Phenotypic performance of isolates was tested using several growth substrates and physicochemical conditions, providing added support for the clustering. Altogether, this study sheds light on the genotypic and phenotypic diversity of L. thermotolerans, contributing to a better understanding of the population structure, ecology and evolution of this non-Saccharomyces yeast.

  18. Synthetic Biology and Metabolic Engineering Approaches and Its Impact on Non-Conventional Yeast and Biofuel Production

    International Nuclear Information System (INIS)

    Madhavan, Aravind; Jose, Anju Alphonsa; Binod, Parameswaran; Sindhu, Raveendran; Sukumaran, Rajeev K.; Pandey, Ashok; Castro, Galliano Eulogio

    2017-01-01

    The increasing fossil fuel scarcity has led to an urgent need to develop alternative fuels. Currently microorganisms have been extensively used for the production of first-generation biofuels from lignocellulosic biomass. Yeast is the efficient producer of bioethanol among all existing biofuels option. Tools of synthetic biology have revolutionized the field of microbial cell factories especially in the case of ethanol and fatty acid production. Most of the synthetic biology tools have been developed for the industrial workhorse Saccharomyces cerevisiae. The non-conventional yeast systems have several beneficial traits like ethanol tolerance, thermotolerance, inhibitor tolerance, genetic diversity, etc., and synthetic biology have the power to expand these traits. Currently, synthetic biology is slowly widening to the non-conventional yeasts like Hansenula polymorpha, Kluyveromyces lactis, Pichia pastoris, and Yarrowia lipolytica. Herein, we review the basic synthetic biology tools that can apply to non-conventional yeasts. Furthermore, we discuss the recent advances employed to develop efficient biofuel-producing non-conventional yeast strains by metabolic engineering and synthetic biology with recent examples. Looking forward, future synthetic engineering tools’ development and application should focus on unexplored non-conventional yeast species.

  19. Modelling of the process yields of a whey fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Blakebrough, N; Moresi, M

    1981-01-01

    The biomass yields (y) and COD reduction efficiencies (eta) of a whey fermentation by Kluyveromyces fragilis were studied in a 100-l fermenter at various stirrer speeds and lactose concentrations, and compared to those obtained in 10-l and 15-l fermenters at constant values of the oxygen transfer coefficient (kla) and air velocity. The empirical models previously constructed by using the 15-l fermenter data could be used to predict the yields on the other scales by calculating for each run the 15-l fermenter which would provide the same oxygen transfer coefficient measured by the sulfite method on each fermenter under study. To make this model independent of stirrer speeds used in each generic fermenter, the effect of aeration and mixing was incorporated into an overall parameter (kla) and the values of y and eta were correlated only with temperature, lactose level and kla, since these variables were approximately orthogonal. The validity of this model was finally checked against the yields reported by Wasserman et al. (1961) in a 6-cubic metre fermenter, thus confirming the capability of the model to provide a reliable basis for further scale-up on the production scale. (Refs. 17).

  20. Complete utilization of whey for alcohol and methane production

    Energy Technology Data Exchange (ETDEWEB)

    Reesen, L; Strube, R

    1978-01-01

    The quality of the rectified alcohol obtained by 2-stage fermentation of whey permeate with Kluyveromyces fragilis followed by distillation was similar to that of rectified alcohol from molasses, though composition in terms of fusel oils, aldehydes, and diacetyls was varied. A contact process of anaerobic biological treatment reduced the COD of the effluent from 7000 to 350 and 1000 mg/L in laboratory and full-scale plant experiments respectively. The gas drawn off from this process contained 63% CH/sub 4/ and was almost odorless because of the low S content in the whey permeate; it had an energy value of 1.8 kg fuel oil/m/sup 3/ permeate and was able to replace 17 to 20% of the fuel oil used at the plant. The alcohol yield was 80% of the theoretical yield, and corresponded to the use of 42 L of whey permeate containing 4.4% lactose for production of 1 L of 100% alcohol and the total energy gain was 30%.

  1. Potential applicaton of β-galactosidase in food science and nutrition

    Directory of Open Access Journals (Sweden)

    Nika ŽIBRAT

    2017-10-01

    Full Text Available β-galactosidase is an enzyme with hydrolytic and transgalactosylation activity. The origin of the enzyme dictates the balance between both activities. Industrially used β-galactosidases are obtained with recombinant production from filamentus funghi Aspergillus sp. and yeasts Kluyveromyces sp. Recently thermostabile β-galactosidases have been subject of many research. The enzyme can be industrially used in free or immobilized form. Immobilization often provides better stability, reusability and lower expenses. Application of β-galactosidase is most common in food processing and nutrition, it is also used in medicine and ecology. Hydrolytic activity of the enzyme has long been used for reducing lactose content in milk, while transgalactosylitic activity is used for synthesis of products such as galactooligosaccharides, lactosucrose and others. The latter have a great potential in food industry for obtaining products with reduced lactose content and increasing of nutritional value by adding dietetic fibers such as galactooligosaccharides. Despite the potential it is vital that reaction mechanisms become better understood and optimization is in place in order to reach the usability of this enzyme at industrial level.

  2. Sorption of strontium by magnetically modified yeast cells

    International Nuclear Information System (INIS)

    Hu Yantao; Ji Yanqin; Tian Qing; Shao Xianzhang; Shi Jianhe; Ivo Safarik; Zhang Shengdong; Li Jinying

    2008-01-01

    Magnetically modified fodder's yeast (Kluyveromyces fragilis) cells using water based magnetic fluid, were characterized by scanning electron microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The sorption-desorption properties of Sr 2+ by these yeast cells from nitrate salt of Sr 2+ were studied. The results demonstrated that the Sr 2+ sorption volume by these cells enhanced with increasing pH and reached a plateau between pH 4.0 and 7.0. A minor effect by temperature was observed. The sorption volumes are 19.5 mg/g and 53.5 mg/g from 10 ppm and 40 ppm Sr 2+ solution respectively within 20 min. The sorption of Sr 2+ in these cells can be desorbed under 0.1 mol/L HNO 3 solution. The maximum Sr 2+ sorption volume is 96.7 mg/g at 20℃. The sorption characteristic fits Langmuir model well with 140.8 mg/g calculated maximum sorption volume by these yeast cells. (authors)

  3. Microbial diversity in raw milk and traditional fermented dairy products (Hurood cheese and Jueke) from Inner Mongolia, China.

    Science.gov (United States)

    Gao, M L; Hou, H M; Teng, X X; Zhu, Y L; Hao, H S; Zhang, G L

    2017-03-08

    Hurood cheese (HC) and Jueke (Jk) are 2 traditional fermented dairy products produced from raw milk (RM) in the Inner Mongolia region of China. They have a long history of production and consumption. The microbial compositions of RM, HC, and Jk vary greatly, and are influenced by their geographical origins and unique processing methods. In this study, 2 batches of RM, HC, and Jk samples were collected (April and August 2015) from the Zhenglan Banner, a region located in the southern part of Inner Mongolian belonging to the Xilingol league prefecture. The bacterial and fungal diversities of the samples were determined by 16S rRNA and 18S rRNA gene sequence analysis, respectively. A total of 112 bacterial and 30 fungal sequences were identified, with Firmicutes and Ascomycota being the predominant phyla for bacteria and fungi, respectively. Lactococcus and Lactobacillus were identified as the main bacterial genera, whereas Kluyveromyces was the predominant fungus identified in the 3 dairy products. Different bacterial and fungal compositions were observed in RM, HC, and Jk samples collected at different times. These results suggested that time of production may be an important factor influencing the microbial diversity present in RM, HC, and Jk.

  4. Use of a Yeast tRNase Killer Toxin to Diagnose Kti12 Motifs Required for tRNA Modification by Elongator.

    Science.gov (United States)

    Mehlgarten, Constance; Prochaska, Heike; Hammermeister, Alexander; Abdel-Fattah, Wael; Wagner, Melanie; Krutyhołowa, Rościsław; Jun, Sang Eun; Kim, Gyung-Tae; Glatt, Sebastian; Breunig, Karin D; Stark, Michael J R; Schaffrath, Raffael

    2017-09-05

    Saccharomyces cerevisiae cells are killed by zymocin, a tRNase ribotoxin complex from Kluyveromyces lactis , which cleaves anticodons and inhibits protein synthesis. Zymocin's action requires specific chemical modification of uridine bases in the anticodon wobble position (U34) by the Elongator complex (Elp1-Elp6). Hence, loss of anticodon modification in mutants lacking Elongator or related KTI ( K. lactis Toxin Insensitive) genes protects against tRNA cleavage and confers resistance to the toxin. Here, we show that zymocin can be used as a tool to genetically analyse KTI12 , a gene previously shown to code for an Elongator partner protein. From a kti12 mutant pool of zymocin survivors, we identify motifs in Kti12 that are functionally directly coupled to Elongator activity. In addition, shared requirement of U34 modifications for nonsense and missense tRNA suppression ( SUP4 ; SOE1 ) strongly suggests that Kti12 and Elongator cooperate to assure proper tRNA functioning. We show that the Kti12 motifs are conserved in plant ortholog DRL1/ELO4 from Arabidopsis thaliana and seem to be involved in binding of cofactors (e.g., nucleotides, calmodulin). Elongator interaction defects triggered by mutations in these motifs correlate with phenotypes typical for loss of U34 modification. Thus, tRNA modification by Elongator appears to require physical contact with Kti12, and our preliminary data suggest that metabolic signals may affect proper communication between them.

  5. Simultaneous enzymatic hydrolysis and lactic fermentation to obtain a yogurt with low lactose content Hidrólise enzimática e fermentação lática simultâneas na obtenção de um iogurte com baixo teor de lactose

    Directory of Open Access Journals (Sweden)

    André Rosa Martins

    2012-10-01

    Full Text Available In a single-stage process with the simultaneous addition of β-galactosidase and lactic culture, the lactose conversion, the processing time, viscosity and syneresis were evaluated. Fermentation was promoted by lactic culture containing two probiotic microorganisms, Bifidobacterium animalis and Lactobacillus acidophilus, associated with the typical microorganisms of yogurt. An enzymatic preparation containing β-galactosidases from Kluyveromyces lactis and Aspergillus niger was used. A central composite design (2³ trials plus three central points was proposed in order to evaluate the effects of initial lactose concentration, enzyme concentration and the time of addition of the enzyme. The following conditions were established: initial lactose concentration of 91 g L-1, enzyme concentration of 0.5 g L-1 and enzyme addition at the beginning of fermentation. In these conditions, a decrease in processing time (from 4.55 to 3.68 h and an increase in lactose conversion (from 15.2 to 97.9% were observed in relation to the fermentation without enzyme addition, and no detrimental changes in some physical properties of yogurt (viscosity, and syneresis.No processo em um único estágio com a adição simultânea de β-galactosidase e de cultura lática, foram avaliadas a conversão da lactose, o tempo de processamento, a viscosidade e a sinérese. A fermentação foi promovida por cultura láctica, contendo dois micro-organismos probióticos, Bifidobacterium animalis e Lactobacillus acidophilus, associados aos micro-organismos característicos do iogurte. Foi utilizado um preparado enzimático contendoβ-galactosidases obtidas de Kluyveromyces lactis e de Aspergillus niger. Os efeitos da concentração inicial de lactose, concentração de enzima e tempo de adição da enzima foram avaliados por meio de um planejamento experimental (2³ ensaios mais três pontos centrais. As seguintes condições foram estabelecidas: concentração inicial de lactose de

  6. Systematic discovery of unannotated genes in 11 yeast species using a database of orthologous genomic segments

    LENUS (Irish Health Repository)

    OhEigeartaigh, Sean S

    2011-07-26

    Abstract Background In standard BLAST searches, no information other than the sequences of the query and the database entries is considered. However, in situations where two genes from different species have only borderline similarity in a BLAST search, the discovery that the genes are located within a region of conserved gene order (synteny) can provide additional evidence that they are orthologs. Thus, for interpreting borderline search results, it would be useful to know whether the syntenic context of a database hit is similar to that of the query. This principle has often been used in investigations of particular genes or genomic regions, but to our knowledge it has never been implemented systematically. Results We made use of the synteny information contained in the Yeast Gene Order Browser database for 11 yeast species to carry out a systematic search for protein-coding genes that were overlooked in the original annotations of one or more yeast genomes but which are syntenic with their orthologs. Such genes tend to have been overlooked because they are short, highly divergent, or contain introns. The key features of our software - called SearchDOGS - are that the database entries are classified into sets of genomic segments that are already known to be orthologous, and that very weak BLAST hits are retained for further analysis if their genomic location is similar to that of the query. Using SearchDOGS we identified 595 additional protein-coding genes among the 11 yeast species, including two new genes in Saccharomyces cerevisiae. We found additional genes for the mating pheromone a-factor in six species including Kluyveromyces lactis. Conclusions SearchDOGS has proven highly successful for identifying overlooked genes in the yeast genomes. We anticipate that our approach can be adapted for study of further groups of species, such as bacterial genomes. More generally, the concept of doing sequence similarity searches against databases to which external

  7. Use of non-saccharomyces Torulaspora delbrueckii yeast strains in winemaking and brewing

    Directory of Open Access Journals (Sweden)

    Tataridis Panagiotis

    2013-01-01

    Full Text Available Selected Saccharomyces yeast strains have been used for more than 150 years in brewing and for several decades in winemaking. They are necessary in brewing because of the boiling of the wort, which results in the death of all yeast cells, with the exception of some Belgian style beers (ex. Lambic, where the wort is left to be colonized by indigenous yeast and bacteria from the environment and ferment naturally. In winemaking their use is also pertinent because they provide regular and timely fermentations, inhibit the growth of indigenous spoilage microorganisms and contribute to the desired sensory characters. Even though the use of selected Saccharomyces strains provides better quality assurance in winemaking in comparison to the unknown microbial consortia in the must, it has been debated for a long time now whether the use of selected industrial Saccharomyces strains results in wines with less sensory complexity and “terroir” character. In previous decades, non-Saccharomyces yeasts were mainly considered as spoilage/problematic yeast, since they exhibited low fermentation ability and other negative traits. In the last decades experiments have shown that there are some non-Saccharomyces strains (Candida, Pichia, Kluyveromyces, Torulaspora, etc which, even though they are not able to complete the fermentation they can still be used in sequential inoculation-fermentation with Saccharomyces to increase sensory complexity of the wines. Through fermentation in a laboratory scale, we have observed that the overall effects of selected Torulaspora delbrueckii yeast strains, is highly positive, leading to products with pronounced sensory complexity and floral/fruity aroma in winemaking and brewing.

  8. Sequencing-Based Analysis of the Bacterial and Fungal Composition of Kefir Grains and Milks from Multiple Sources

    Science.gov (United States)

    Marsh, Alan J.; O’Sullivan, Orla; Hill, Colin; Ross, R. Paul; Cotter, Paul D.

    2013-01-01

    Kefir is a fermented milk-based beverage to which a number of health-promoting properties have been attributed. The microbes responsible for the fermentation of milk to produce kefir consist of a complex association of bacteria and yeasts, bound within a polysaccharide matrix, known as the kefir grain. The consistency of this microbial population, and that present in the resultant beverage, has been the subject of a number of previous, almost exclusively culture-based, studies which have indicated differences depending on geographical location and culture conditions. However, culture-based identification studies are limited by virtue of only detecting species with the ability to grow on the specific medium used and thus culture-independent, molecular-based techniques offer the potential for a more comprehensive analysis of such communities. Here we describe a detailed investigation of the microbial population, both bacterial and fungal, of kefir, using high-throughput sequencing to analyse 25 kefir milks and associated grains sourced from 8 geographically distinct regions. This is the first occasion that this technology has been employed to investigate the fungal component of these populations or to reveal the microbial composition of such an extensive number of kefir grains or milks. As a result several genera and species not previously identified in kefir were revealed. Our analysis shows that the bacterial populations in kefir are dominated by 2 phyla, the Firmicutes and the Proteobacteria. It was also established that the fungal populations of kefir were dominated by the genera Kazachstania, Kluyveromyces and Naumovozyma, but that a variable sub-dominant population also exists. PMID:23894461

  9. Oral microflora and their relation to risk factors in HIV+ patients with oropharyngeal candidiasis.

    Science.gov (United States)

    Sharifzadeh, A; Khosravi, A R; Shokri, H; Asadi Jamnani, F; Hajiabdolbaghi, M; Ashrafi Tamami, I

    2013-06-01

    The purpose of this study was to determine the prevalence of oral microflora and association of oral candidiasis and multiple risk factors in HIV(+) patients. The present study included 100 HIV-infected patients participated in Imam Khomeini Hospital, Tehran, Iran for Oropharyngeal candidiasis (OPC) and HIV. We assessed the presence or absence of OPC, and samples were obtained from the oral cavity and direct microscopic examination, gram staining and culture on standard microbiological media were performed in all patients. CD4(+) cell count/CD4(+) percentage were also calculated. The demographic characteristics showed that the patients had a mean age of 32.3 years old, 78% male and 22% female. Patients belonging to 'O(+)' blood group (27%) were more prone to develop OPC. A total of 460 bacterial colonies were obtained and Streptococcus mutans (15.4%) was the most frequently isolated species in the HIV(+) patients, followed by Staphylococcus epidermidis (12.8%) and Corynebacterium (8.7%). In addition, 254 yeasts (from four different genera) were isolated from the patient under study. Candida species (94.4%) were the most frequently obtained genera, followed by Saccharomyces (2.4%), Kluyveromyces and Cryptococcus (1.6% for both) species. Candida albicans (37.2%) was the most common species isolated from HIV(+) patients with OPC and its frequency was significantly higher than that of other Candida species (Poral cavity of HIV(+) patients and there was no significant difference of the variables CD4(+) cell count and yeast counts. The findings of this study would be helpful in any further study, which, if done prospectively on a large cohort, can be confirmatory. Copyright © 2013. Published by Elsevier SAS.

  10. Presence and distribution of yeasts in the reproductive tract in healthy female horses.

    Science.gov (United States)

    Azarvandi, A; Khosravi, A R; Shokri, H; Talebkhan Garoussi, M; Gharahgouzlou, F; Vahedi, G; Sharifzadeh, A

    2017-09-01

    Yeasts are commensal organisms found in the reproductive and gastrointestinal tracts, and on the skin and other mucosa in mammals. The purpose of this study was to isolate and identify yeast flora in the caudal reproductive tract in healthy female horses. Longitudinal study. A total of 453 samples were collected using double-guarded swabs from the vestibule, clitoral fossa and vagina in 151 horses. All samples were cultured on Sabouraud 4% dextrose agar and incubated at 35°C for 7-10 days. Isolates were identified according to their morphological characteristics and biochemical profiles. Yeast colonies were isolated from 60 (39.7%) of the 151 horses. The isolated yeasts belonged to nine genera, and included Candida spp. (53.2%), Cryptococcus spp. (12.2%), Saccharomyces spp. (10.5%), Geotrichum spp. (8.0%), Rhodotorula spp. (7.1%), Malassezia spp. (3.7%), Trichosporon spp. (2.6%), Kluyveromyces spp. (2.6%) and Sporothrix spp. (0.2%). Candida krusei (43.1%) was the most frequent Candida species isolated. There was a significant difference in prevalence between C. krusei and other Candida species (Pyeast isolates (48.0%) than the vagina (18.3%). The isolation of yeast colonies from multiparous females (76.8%) was significantly higher than from maiden mares (P<0.05). The study was limited by the difficulty of distinguishing between normal flora and potential pathogens. Candida spp., in particular C. krusei, represent important flora resident in the caudal reproductive tract in healthy female horses. This is particularly important in contexts that require the initiation of empirical treatment prior to the completion of culture results. © 2016 EVJ Ltd.

  11. Synthesis of the Galactosyl Derivative of Gluconic Acid With the Transglycosylation Activity of β-Galactosidase

    Directory of Open Access Journals (Sweden)

    Aleksandra Wojciechowska

    2017-01-01

    Full Text Available Bionic acids are bioactive compounds demonstrating numerous interesting properties. They are widely produced by chemical or enzymatic oxidation of disaccharides. This paper focuses on the galactosyl derivative of gluconic acid as a result of a new method of bionic acid synthesis which utilises the transglycosylation properties of β-galactosidase and introduces lactose as a substrate. Products obtained in such a process are characterised by different structures (and, potentially, properties than those resulting from traditional oxidation of disaccharides. The aim of this study is to determine the effect of selected parameters (concentration and ratio of substrates, dose of the enzyme, time, pH, presence of salts on the course of the reaction carried out with the enzymatic preparation Lactozym, containing β-galactosidase from Kluyveromyces lactis. Research has shown that increased dry matter content in the baseline solution (up to 50 %, by mass per volume and an addition of NaCl contribute to higher yield. On the other hand, reduced content of the derivative is a result of increased pH from 7.0 to 9.0 and an addition of magnesium and manganese salts. Moreover, exceeding the β-galactosidase dose over approx. 35 000 U per 100 g of lactose also leads to reduced yield of the process. The most favourable molar ratio of sodium gluconate to lactose is 2.225:0.675. Depending on the conditions of the synthesis, the product concentration ranged between 17.3 and 118.3 g/L of the reaction mixture, which corresponded to the mass fraction of 6.64–23.7 % of dry matter. The data obtained as a result of the present study may be useful for designing an industrial process.

  12. Spectroscopic study, antimicrobial activity and crystal structures of N-(2-hydroxy-5-nitrobenzalidene)4-aminomorpholine and N-(2-hydroxy-1-naphthylidene)4-aminomorpholine

    Science.gov (United States)

    Yıldız, Mustafa; Ünver, Hüseyin; Dülger, Başaran; Erdener, Diğdem; Ocak, Nazan; Erdönmez, Ahmet; Durlu, Tahsin Nuri

    2005-03-01

    Schiff bases N-(2-hydroxy-3-nitrobenzalidene)4-aminomorpholine ( 1) and N-(2-hydroxy-1-naphthylidene)4-aminomorpholine ( 2) were synthesized from the reaction of 4-aminomorpholine with 2-hydroxy-5-nitrobenzaldehyde and 2-hydroxy-1-naphthaldehyde. Compounds 1 and 2 were characterized by elemental analysis, IR, 1H NMR, 13C NMR and UV-Visible techniques. The UV-Visible spectra of the Schiff bases with OH group in ortho position to the imino group were studied in polar and nonpolar solvents in acidic and basic media. The structures of compounds 1 and 2 have been examined cyrstallographically, for two compounds exist as dominant form of enol-imines in both the solutions and solid state. The title compounds 1 and 2 crystallize in the monoclinic space group P2 1/ c and P2 1/ n with unit cell parameters: a=8.410(1) and 11.911(3), b=6.350(9) and 4.860(9), c=21.728(3) and 22.381(6) Å, β=90.190(1) and 95.6(2)°, V=1160.6(3) and 1289.5(5) Å 3, Dx=1.438 and 1.320 g cm -3, respectively. The crystal structures were solved by direct methods and refined by full-matrix least squares. The antimicrobial activities of compounds 1 and 2 have also been studied. The antimicrobial activities of the ligands have been screened in vitro against the organisms Escherichia coli ATCC 11230, Staphylococcus aureus ATCC 6538, Klebsiella pneumoniae UC57, Micrococcus luteus La 2971, Proteus vulgaris ATCC 8427, Pseudomonas aeruginosa ATCC 27853, Mycobacterium smegmatis CCM 2067, Bacillus cereus ATCC 7064, Listeria monocytogenes ATCC 15313, Candida albicans ATCC 10231, Kluyveromyces fragilis NRRL 2415, Rhodotorula rubra DSM 70403, Debaryomyces hansenii DSM 70238 and Hanseniaspora guilliermondii DSM 3432.

  13. The Croft Nursing Home, 2 Goldenbridge Walk, Inchicore, Dublin 8.

    LENUS (Irish Health Repository)

    OhEigeartaigh, Sean S

    2011-07-26

    Abstract Background In standard BLAST searches, no information other than the sequences of the query and the database entries is considered. However, in situations where two genes from different species have only borderline similarity in a BLAST search, the discovery that the genes are located within a region of conserved gene order (synteny) can provide additional evidence that they are orthologs. Thus, for interpreting borderline search results, it would be useful to know whether the syntenic context of a database hit is similar to that of the query. This principle has often been used in investigations of particular genes or genomic regions, but to our knowledge it has never been implemented systematically. Results We made use of the synteny information contained in the Yeast Gene Order Browser database for 11 yeast species to carry out a systematic search for protein-coding genes that were overlooked in the original annotations of one or more yeast genomes but which are syntenic with their orthologs. Such genes tend to have been overlooked because they are short, highly divergent, or contain introns. The key features of our software - called SearchDOGS - are that the database entries are classified into sets of genomic segments that are already known to be orthologous, and that very weak BLAST hits are retained for further analysis if their genomic location is similar to that of the query. Using SearchDOGS we identified 595 additional protein-coding genes among the 11 yeast species, including two new genes in Saccharomyces cerevisiae. We found additional genes for the mating pheromone a-factor in six species including Kluyveromyces lactis. Conclusions SearchDOGS has proven highly successful for identifying overlooked genes in the yeast genomes. We anticipate that our approach can be adapted for study of further groups of species, such as bacterial genomes. More generally, the concept of doing sequence similarity searches against databases to which external

  14. Sequencing-based analysis of the bacterial and fungal composition of kefir grains and milks from multiple sources.

    Directory of Open Access Journals (Sweden)

    Alan J Marsh

    Full Text Available Kefir is a fermented milk-based beverage to which a number of health-promoting properties have been attributed. The microbes responsible for the fermentation of milk to produce kefir consist of a complex association of bacteria and yeasts, bound within a polysaccharide matrix, known as the kefir grain. The consistency of this microbial population, and that present in the resultant beverage, has been the subject of a number of previous, almost exclusively culture-based, studies which have indicated differences depending on geographical location and culture conditions. However, culture-based identification studies are limited by virtue of only detecting species with the ability to grow on the specific medium used and thus culture-independent, molecular-based techniques offer the potential for a more comprehensive analysis of such communities. Here we describe a detailed investigation of the microbial population, both bacterial and fungal, of kefir, using high-throughput sequencing to analyse 25 kefir milks and associated grains sourced from 8 geographically distinct regions. This is the first occasion that this technology has been employed to investigate the fungal component of these populations or to reveal the microbial composition of such an extensive number of kefir grains or milks. As a result several genera and species not previously identified in kefir were revealed. Our analysis shows that the bacterial populations in kefir are dominated by 2 phyla, the Firmicutes and the Proteobacteria. It was also established that the fungal populations of kefir were dominated by the genera Kazachstania, Kluyveromyces and Naumovozyma, but that a variable sub-dominant population also exists.

  15. Characterization of hexose transporters in Yarrowia lipolytica reveals new groups of Sugar Porters involved in yeast growth.

    Science.gov (United States)

    Lazar, Zbigniew; Neuvéglise, Cécile; Rossignol, Tristan; Devillers, Hugo; Morin, Nicolas; Robak, Małgorzata; Nicaud, Jean-Marc; Crutz-Le Coq, Anne-Marie

    2017-03-01

    Sugar assimilation has been intensively studied in the model yeast S. cerevisiae, and for two decades, it has been clear that the homologous HXT genes, which encode a set of hexose transporters, play a central role in this process. However, in the yeast Yarrowia lipolytica, which is well-known for its biotechnological applications, sugar assimilation is only poorly understood, even though this yeast exhibits peculiar intra-strain differences in fructose uptake: some strains (e.g., W29) are known to be slow-growing in fructose while others (e.g., H222) grow rapidly under the same conditions. Here, we retrieved 24 proteins of the Sugar Porter family from these two strains, and determined that at least six of these proteins can function as hexose transporters in the heterologous host Saccharomyces cerevisiae EBY.VW4000. Transcriptional studies and deletion analysis in Y. lipolytica indicated that two genes, YHT1 and YHT4, are probably the main players in both strains, with a similar role in the uptake of glucose, fructose, and mannose at various concentrations. The other four genes appear to constitute a set of 'reservoir' hexose transporters with an as-yet unclear physiological role. Furthermore, through examining Sugar Porters of the entire Yarrowia clade, we show that they constitute a dynamic family, within which hexose transport genes have been duplicated and lost several times. Our phylogenetic analyses support the existence of at least three distinct evolutionary groups of transporters which allow yeasts to grow on hexoses. In addition to the well-known and widespread Hxt-type transporters (which are not essential in Y. lipolytica), we highlight a second group of transporters, represented by Yht1, which are phylogenetically related to sensors that play a regulatory role in S. cerevisiae, and a third group, represented by Yht4, previously thought to contain only high-affinity glucose transporters related to Hgt1of Kluyveromyces lactis. Copyright © 2017

  16. Intracellular β-Glucosidases CEL1a and CEL1b Are Essential for Cellulase Induction on Lactose in Trichoderma reesei

    Science.gov (United States)

    Xu, Jintao; Zhao, Guolei; Kou, Yanbo; Zhang, Weixin; Zhou, Qingxin; Chen, Guanjun

    2014-01-01

    Lactose (1,4-O-β-d-galacto-pyranosyl-d-glucose) induces cellulolytic enzymes in Trichoderma reesei and is in fact one of the most important soluble carbon sources used to produce cellulases on an industrial level. The mechanism underlying the induction is, however, not fully understood. In this study, we investigated the cellular functions of the intracellular β-glucosidases CEL1a and CEL1b in the induction of cellulase genes by lactose in T. reesei. We demonstrated that while CEL1a and CEL1b were functionally equivalent in mediating the induction, the simultaneous absence of these intracellular β-glucosidases abolished cbh1 gene expression on lactose. d-Galactose restored the efficient cellulase gene induction in the Δcel1a strain independently of its reductive metabolism, but not in the Δcel1a Δcel1b strain. A further comparison of the transcriptional responses of the Δcel1a Δcel1b strain complemented with wild-type CEL1a or a catalytically inactive CEL1a version and the Δcel1a strain constitutively expressing CEL1a or the Kluyveromyces lactis β-galactosidase LAC4 showed that both the CEL1a protein and its glycoside hydrolytic activity were indispensable for cellulase induction by lactose. We also present evidence that intracellular β-glucosidase-mediated lactose induction is further conveyed to XYR1 to ensure the efficiently induced expression of cellulase genes. PMID:24879125

  17. Lactose hydrolysis potential and thermal stability of commercial β-galactosidase in UHT and skimmed milk

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    Alessandra BOSSO

    2016-03-01

    Full Text Available Abstract The commercial enzyme (E.C. = 3.2.1.23 from Kluyveromyces lactis (liquid and Aspergillus oryzae(lyophilized was investigated for its hydrolysis potential in lactose substrate, UHT milk, and skimmed milk at different concentrations (0.7; 1.0 and 1.5%, pH values (5.0; 6.0; 6.5 and 7.0, and temperature (30; 35; 40 and 55 ºC. High hydrolysis rates were observed for the enzyme from K. lactis at pH 7.0 and 40 ºC, and from A. oryzae at pH 5.0 and 55 ºC. The enzyme from K. lactis showed significantly higher hydrolysis rates when compared to A. oryzae. The effect of temperature and β-galactosidase concentration on the lactose hydrolysis in UHT milk was higher than in skimmed milk, for all temperatures tested. With respect to the thermal stability, a decrease in hydrolysis rate was observed at pH 6.0 at 35 ºC for K. lactisenzyme, and at pH 6.0 at 55 ºC for the enzyme from A. oryzae. This study investigate the hydrolysis of β-galactosidase in UHT and skimmed milk. The knowledge about the characteristics of the β-galactosidase fromK. lactis and A. oryzae enables to use it most efficiently to control the enzyme concentration, temperature, and pH in many industrial processes and product formulations.

  18. Occurrence, horizontal transfer and degeneration of VDE intein family in Saccharomycete yeasts.

    Science.gov (United States)

    Okuda, Yoshihiro; Sasaki, Daisuke; Nogami, Satoru; Kaneko, Yoshinobu; Ohya, Yoshikazu; Anraku, Yasuhiro

    2003-05-01

    VDE is a homing endonuclease gene originally discovered as an intervening element in VMA1s of Saccharomyces cerevisiae. There have been two independent subfamilies of VDE, one from S. cerevisiae strain X2180-1A and the other from Saccharomyces sp. DH1-1A in the host VMA1 gene, and they share the identity of 96.3%. In order to search the occurrence, intra/interspecies transfer and molecular degeneration of VDE, complete sequences of VMA1 in 10 strains of S. cerevisiae, eight species of saccharomycete yeasts, Candida glabrata and Kluyveromyces lactis were determined. We found that six of 10 S. cerevisiae strains contain VDEs 99.7-100% identical to that of the strain X2180-1A, one has no VDE, whereas the other three harbour VDEs 100% identical to that of the strain DH1-1A. S. carlsbergensis has two VMA1s, one being 99.8% identical to that of the strain X2180-1A with VDE 100% identical to that of the strain DH1-1A and the other containing the same VMA1 in S. pastorianus with no VDE. This and other evidence indicates that intra/interspecies transmissions of VDEs have occurred among saccharomycete yeasts. Phylogenetic analyses of VMA1 and VDE suggest that the S. cerevisiae VDEs had branched earlier than other VDEs from an ancestral VDE and had invaded into the host loci as relatively late events. The two VDEs seemed to degenerate in individual host loci, retaining their splicing capacity intact. The degeneration of the endonuclease domains was distinct and, if compared, its apparent rate was much faster than that of the protein-splicing domains. Copyright 2003 John Wiley & Sons, Ltd.

  19. Molecular Characterization of Yeast Strains Isolated from Different Sources by Restriction Fragment Length Polymorphism

    International Nuclear Information System (INIS)

    Ali, M. S.; Latif, Z.

    2016-01-01

    Various molecular techniques like analysis of the amplified rDNA internal transcribed spacers (ITS), intragenic spacers and total ITS region analysis by restriction fragment length polymorphism (RFLP) has been introduced for yeast identification but there are limited databases to identify yeast species on the basis of 5.8S rDNA. In this study, twenty nine yeast strains from various sources including spoiled fruits, vegetables, foodstuffs, and concentrated juices were characterized by PCR-RFLP. PCR-RFLP has been used to characterize yeasts present in different spoiled food samples after isolation of the yeasts. By using this technique, the isolated yeast strains were characterized by direct 5.8S-ITS rDNA region amplification. RFLP analysis was applied to each of the amplification products (varied from 400bp to 800bp) detected, and the corresponding yeast identifications were made according to each specific restriction patterns obtained after treatment with two endonucleases TaqI and HaeIII which yielded a specific banding pattern for each species. For further confirmation amplified products of eleven selected isolates were sequenced and blast on NCBI. Both RFLP and sequence analyses of the strains with accession nos. KF472163, KF472164, KF472165, KF472166, KF472167, KF472168, KF472169, KF472170, KF472171, KF472172, KF472173 gave significantly similar results. The isolates were found to belong five different yeast species including; Candida spp., Pichia spp., Kluyveromyces spp., Clavispora spp. and Hanseniaspora spp. This method provides a fast, easy, reliable and authentic way for determining yeast population present in different type of samples, as compared to traditional characterization technique. (author)

  20. Long telomeres produced by telomerase-resistant recombination are established from a single source and are subject to extreme sequence scrambling.

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    Jianing Xu

    Full Text Available Considerable evidence now supports the idea that the moderate telomere lengthening produced by recombinational telomere elongation (RTE in a Kluyveromyces lactis telomerase deletion mutant occurs through a roll-and-spread mechanism. However, it is unclear whether this mechanism can account for other forms of RTE that produce much longer telomeres such as are seen in human alternative lengthening of telomere (ALT cells or in the telomerase-resistant type IIR "runaway" RTE such as occurs in the K. lactis stn1-M1 mutant. In this study we have used mutationally tagged telomeres to examine the mechanism of RTE in an stn1-M1 mutant both with and without telomerase. Our results suggest that the establishment stage of the mutant state in newly generated stn1-M1 ter1-Δ mutants surprisingly involves a first stage of sudden telomere shortening. Our data also show that, as predicted by the roll-and-spread mechanism, all lengthened telomeres in a newly established mutant cell commonly emerge from a single telomere source. However, in sharp contrast to the RTE of telomerase deletion survivors, we show that the RTE of stn1-M1 ter1-Δ cells produces telomeres whose sequences undergo continuous intense scrambling via recombination. While telomerase was not necessary for the long telomeres in stn1-M1 cells, its presence during their establishment was seen to interfere with the amplification of repeats via recombination, a result consistent with telomerase retaining its ability to add repeats during active RTE. Finally, we observed that the presence of active mismatch repair or telomerase had important influences on telomeric amplification and/or instability.

  1. Controlled production of Camembert-type cheeses. Part II. Changes in the concentration of the more volatile compounds.

    Science.gov (United States)

    Leclercq-Perlat, Marie-Noëlle; Latrille, Eric; Corrieu, Georges; Spinnler, Henry-Eric

    2004-08-01

    Flavour generation in cheese is a major aspect of ripening. In order to enhance aromatic qualities it is necessary to better understand the chemical and microbiological changes. Experimental Camembert-type cheeses were prepared in duplicate from pasteurized milk inoculated with Kluyveromyces lactis, Geotrichum candidum, Penicillium camemberti and Brevibacterium linens under aseptic conditions. Two replicates performed under controlled conditions of temperature (12 degrees C), relative humidity (95 +/- 2%), and atmosphere showed similar ripening characteristics. The evolutions of metabolite concentrations were studied during ripening. The volatile components were extracted by dynamic headspace extraction, separated and quantified by gas chromatography and identified by mass spectrometry. For each cheese the volatile concentrations varied with the part considered (rind or core). Except for ethyl acetate and 2-pentanone, the volatile quantities observed were higher than their perception thresholds. The flavour component production was best correlated with the starter strains. During the first 10 days the ester formations (ethyl, butyl and isoamyl acetates) were associated with the concentrations of K. lactis and G. candidum. The rind quantity of esters was lower than that observed in core probably due to (1) a diffusion from the core to the surface and (2) evaporation from the surface to the chamber atmosphere. G. candidum and Brev. linens association produced 3 methyl butanol and methyl 3-butanal from leucine, respectively. DMDS came from the methionine catabolism due to Brev. linens. Styrene production was attributed to Pen. camemberti. 2-Pentanone evolution was associated with Pen. camemberti spores and G. candidum. 2-Heptanone changes were not directly related to flora activities while 2-octanone production was essentially due to G. candidum. This study also demonstrates the determining role of volatile component diffusion.

  2. Sequencing-based analysis of the bacterial and fungal composition of kefir grains and milks from multiple sources.

    Science.gov (United States)

    Marsh, Alan J; O'Sullivan, Orla; Hill, Colin; Ross, R Paul; Cotter, Paul D

    2013-01-01

    Kefir is a fermented milk-based beverage to which a number of health-promoting properties have been attributed. The microbes responsible for the fermentation of milk to produce kefir consist of a complex association of bacteria and yeasts, bound within a polysaccharide matrix, known as the kefir grain. The consistency of this microbial population, and that present in the resultant beverage, has been the subject of a number of previous, almost exclusively culture-based, studies which have indicated differences depending on geographical location and culture conditions. However, culture-based identification studies are limited by virtue of only detecting species with the ability to grow on the specific medium used and thus culture-independent, molecular-based techniques offer the potential for a more comprehensive analysis of such communities. Here we describe a detailed investigation of the microbial population, both bacterial and fungal, of kefir, using high-throughput sequencing to analyse 25 kefir milks and associated grains sourced from 8 geographically distinct regions. This is the first occasion that this technology has been employed to investigate the fungal component of these populations or to reveal the microbial composition of such an extensive number of kefir grains or milks. As a result several genera and species not previously identified in kefir were revealed. Our analysis shows that the bacterial populations in kefir are dominated by 2 phyla, the Firmicutes and the Proteobacteria. It was also established that the fungal populations of kefir were dominated by the genera Kazachstania, Kluyveromyces and Naumovozyma, but that a variable sub-dominant population also exists.

  3. Industrial alcohol production via whey and grain fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Friend, B A; Cunningham, M L; Shahani, K M

    1982-01-01

    Six strains of a trained lactose fermenting Kluyveromyces yeast were examined for their ability to utilise lactose in sweet-whey permeate. All strains of K. fragilis tested reduced the concentration of the 5.1% lactose, initially present in whey permeate, to 0.1-0.2% within 48h. Periodic adjustment to maintain the pH during fermentation did not alter the lactose utilisation. The fermentation efficiency of K. fragilis was then compared with that of a mixture of K. fragilis and the classical alcohol fermenter Saccharomyces cerevisiae to verify that no unfavourable interactions occurred in the mixed culture. There were no differences in lactose utilisation or ethanol production between the two groups; both produced approximately 2% ethanol within 24h. This represented approximately 80% of the alcohol which theoretically could be produced from the 5.1% lactose present in the permeate. Whey permeate was also incorporated into the classical grain fermentation by substitution for one-half the water normally added to produce the mash. Fermentation was nearly complete by 36h and alcohol levels ranged from 9.7% for the mixed culture to 9.4% for the K. fragilis and 9.3% for the S. cerevisiae. Since the whey provided significant levels of fermentable sugars, studies were also conducted in which undiluted whey permeate was substituted for all of the water in the mash and the amount of grain was reduced by 20%. At the end of 36h K. fragilis produced 10.9% alcohol and at 60 h of fermentation the level had reached 12.2%. When whole sweet-whey was used, similar levels of alcohol were produced. (Refs. 20).

  4. Comparison of the effectivities of two-phase and single-phase anaerobic sequencing batch reactors during dairy wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Goebloes, Sz.; Portoero, P.; Bordas, D.; Kalman, M.; Kiss, I. [Institute for Biotechnology, Bay Zoltan Foundation for Applied Research, H-6726 Szeged (Hungary)

    2008-05-15

    The performances of anaerobic sequencing batch reactors fed with two different substrates were studied. The substrates were raw acid whey and acid whey fermented with Kluyveromyces lactis in order to investigate the suitability of ethanol for biogas production. The organic loading rates (OLRs) during the experiment ranged from 1.6 to 12.8 g COD dm{sup -3} d{sup -1} and the corresponding decreasing hydraulic retention times from 40 to 5 days for both reactor systems. The efficiency of each system depended on the OLR: the highest COD removal rate was observed at the lowest OLR applied (about 100% in both systems), and at maximum OLR the COD removal efficiency was 68% for the reactors fed with the raw whey and 80% for those fed with the pre-fermented whey. Under the same high OLR conditions the methane yield was 0.122 dm{sup -3} CH{sub 4} g{sup -1} COD{sub degraded} for the anaerobic digesters fed with the untreated whey, and 0.197 dm{sup -3} CH{sub 4} g{sup -1} COD{sub degraded} for those fed with the pre-fermented whey. The digesters functioned without pH control. At the maximum OLR the pH in the reactors fed with the raw acid whey was 5.1, while in those fed with the pre-fermented whey it was 7.15. The results demonstrate that the use of the pre-fermented acid whey as substrate for anaerobic digestion without pH control is feasible, especially at high OLR levels. This substrate is preferable to the raw acid whey, because of the ethanol formed as a non-acidic fermentation product of the yeast. (author)

  5. Combined phylogeny and neighborhood analysis of the evolution of the ABC transporters conferring multiple drug resistance in hemiascomycete yeasts

    Directory of Open Access Journals (Sweden)

    Goffeau André

    2009-10-01

    Full Text Available Abstract Background Pleiotropic Drug Resistant transporters (PDR are members of the ATP-Binding Cassette (ABC subfamily which export antifungals and other xenobiotics in fungi and plants. This subfamily of transmembrane transporters has nine known members in Saccharomyces cerevisiae. We have analyzed the complex evolution of the pleiotropic drug resistance proteins (Pdrp subfamily where gene duplications and deletions occur independently in individual genomes. This study was carried out on 62 Pdrp from nine hemiascomycetous species, seven of which span 6 of the 14 clades of the Saccharomyces complex while the two others species, Debaryomyces hansenii and Yarrowia lipolytica, are further apart from an evolutive point of view. Results Combined phylogenetic and neighborhood analyses enabled us to identify five Pdrp clusters in the Saccharomyces complex. Three of them comprise orthologs of the Pdrp sensu stricto, Pdr5p, Pdr10p, Pdr12p, Pdr15p, Snq2p and YNR070wp. The evolutive pathway of the orthologs of Snq2 and YNR070w is particularly complex due to a tandem gene array in Eremothecium gossypii, Kluyveromyces lactis and Saccharomyces (Lachancea kluyveri. This pathway and different cases of duplications and deletions were clarified by using a neighborhood analysis based on synteny. For the two distant species, Yarrowia lipolytica and Debaryomyces hansenii, no neighborhood evidence is available for these clusters and many homologs of Pdr5 and Pdr15 are phylogenetically assigned to species-based clusters. Two other clusters comprise the orthologs of the sensu lato Pdrp, Aus1p/Pdr11p and YOL075cp respectively. The evolutionary pathway of these clusters is simpler. Nevertheless, orthologs of these genes are missing in some species. Conclusion Numerous duplications were traced among the Hemiascomycetous Pdrp studied. The role of the Whole Genome Duplication (WGD is sorted out and our analyses confirm the common ancestrality of Pdr5p and Pdr15p. A tandem

  6. Combined phylogeny and neighborhood analysis of the evolution of the ABC transporters conferring multiple drug resistance in hemiascomycete yeasts.

    Science.gov (United States)

    Seret, Marie-Line; Diffels, Julie F; Goffeau, André; Baret, Philippe V

    2009-10-01

    Pleiotropic Drug Resistant transporters (PDR) are members of the ATP-Binding Cassette (ABC) subfamily which export antifungals and other xenobiotics in fungi and plants. This subfamily of transmembrane transporters has nine known members in Saccharomyces cerevisiae. We have analyzed the complex evolution of the pleiotropic drug resistance proteins (Pdrp) subfamily where gene duplications and deletions occur independently in individual genomes. This study was carried out on 62 Pdrp from nine hemiascomycetous species, seven of which span 6 of the 14 clades of the Saccharomyces complex while the two others species, Debaryomyces hansenii and Yarrowia lipolytica, are further apart from an evolutive point of view. Combined phylogenetic and neighborhood analyses enabled us to identify five Pdrp clusters in the Saccharomyces complex. Three of them comprise orthologs of the Pdrp sensu stricto, Pdr5p, Pdr10p, Pdr12p, Pdr15p, Snq2p and YNR070wp. The evolutive pathway of the orthologs of Snq2 and YNR070w is particularly complex due to a tandem gene array in Eremothecium gossypii, Kluyveromyces lactis and Saccharomyces (Lachancea) kluyveri. This pathway and different cases of duplications and deletions were clarified by using a neighborhood analysis based on synteny. For the two distant species, Yarrowia lipolytica and Debaryomyces hansenii, no neighborhood evidence is available for these clusters and many homologs of Pdr5 and Pdr15 are phylogenetically assigned to species-based clusters. Two other clusters comprise the orthologs of the sensu lato Pdrp, Aus1p/Pdr11p and YOL075cp respectively. The evolutionary pathway of these clusters is simpler. Nevertheless, orthologs of these genes are missing in some species. Numerous duplications were traced among the Hemiascomycetous Pdrp studied. The role of the Whole Genome Duplication (WGD) is sorted out and our analyses confirm the common ancestrality of Pdr5p and Pdr15p. A tandem gene array is observed in Eremothecium gossypii. One

  7. Elaboration of a bioprepared with probiotic effect from a mixed culture of lactic bacteria and yeasts

    Directory of Open Access Journals (Sweden)

    Miranda Yuquilema J.E.

    2017-02-01

    Full Text Available El uso de microorganismos benéficos adicionados en la alimentación viene desarrollándose desde los años 1900. El presente trabajo tiene el objetivo de elaborar un biopreparado a partir de un cultivo mixto de bacterias lácticas y levaduras. El sustrato del biopreparado contenía 57,5% vinaza de naranja y 30% melaza de caña de azúcar. Las cepas L acidophillus, L bulgaricus, S thermophillus, Kluyveromyces fragilis L-4uclv y Saccharomyces cerevisiae se cultivó en leche esterilizada. Posteriormente se inoculó el 12,5% en el sustrato melaza-vinaza. Finalmente se incubó a 37ºC por 24 h. Los resultados del biopreparado fue 18% Materia seca, 3,3% Ceniza, 19% Proteína cruda, 12% Proteína verdadera y 3,2% Extracto etéreo. La concentración microbiana 9x109 UFC/mL, 0,75% ácido láctico y 95% viabilidad. Color mediante CIELab* System: L*31,85; a*11,48; b*24,52; C*27,08 y H64,91 y similar al código HTML # 61382B. El pH inicial del biopreparado fue 4.4, transcurrido 72 h se estabilizó en 3,86 manteniendo ese valor hasta 90 días pos elaborado a 12 ±2ºC. No hubo diferencia en las características físicas, pero si se mostraron diferencias (P<0,05 en los parámetros bromatológicos y microbiológicos. Los resultados mostraron que los subproductos agroindustriales como la vinaza y la melaza son buenos y económicos para desarrollar biopreparado y obtener un probiótico aceptable para la alimentación animal

  8. Separable Crossover-Promoting and Crossover-Constraining Aspects of Zip1 Activity during Budding Yeast Meiosis.

    Directory of Open Access Journals (Sweden)

    Karen Voelkel-Meiman

    2015-06-01

    Full Text Available Accurate chromosome segregation during meiosis relies on the presence of crossover events distributed among all chromosomes. MutSγ and MutLγ homologs (Msh4/5 and Mlh1/3 facilitate the formation of a prominent group of meiotic crossovers that mature within the context of an elaborate chromosomal structure called the synaptonemal complex (SC. SC proteins are required for intermediate steps in the formation of MutSγ-MutLγ crossovers, but whether the assembled SC structure per se is required for MutSγ-MutLγ-dependent crossover recombination events is unknown. Here we describe an interspecies complementation experiment that reveals that the mature SC is dispensable for the formation of Mlh3-dependent crossovers in budding yeast. Zip1 forms a major structural component of the budding yeast SC, and is also required for MutSγ and MutLγ-dependent crossover formation. Kluyveromyces lactis ZIP1 expressed in place of Saccharomyces cerevisiae ZIP1 in S. cerevisiae cells fails to support SC assembly (synapsis but promotes wild-type crossover levels in those nuclei that progress to form spores. While stable, full-length SC does not assemble in S. cerevisiae cells expressing K. lactis ZIP1, aggregates of K. lactis Zip1 displayed by S. cerevisiae meiotic nuclei are decorated with SC-associated proteins, and K. lactis Zip1 promotes the SUMOylation of the SC central element protein Ecm11, suggesting that K. lactis Zip1 functionally interfaces with components of the S. cerevisiae synapsis machinery. Moreover, K. lactis Zip1-mediated crossovers rely on S. cerevisiae synapsis initiation proteins Zip3, Zip4, Spo16, as well as the Mlh3 protein, as do the crossovers mediated by S. cerevisiae Zip1. Surprisingly, however, K. lactis Zip1-mediated crossovers are largely Msh4/Msh5 (MutSγ-independent. This separation-of-function version of Zip1 thus reveals that neither assembled SC nor MutSγ is required for Mlh3-dependent crossover formation per se in budding yeast

  9. Yarrowia lipolytica vesicle-mediated protein transport pathways

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    Beckerich Jean-Marie

    2007-11-01

    Full Text Available Abstract Background Protein secretion is a universal cellular process involving vesicles which bud and fuse between organelles to bring proteins to their final destination. Vesicle budding is mediated by protein coats; vesicle targeting and fusion depend on Rab GTPase, tethering factors and SNARE complexes. The Génolevures II sequencing project made available entire genome sequences of four hemiascomycetous yeasts, Yarrowia lipolytica, Debaryomyces hansenii, Kluyveromyces lactis and Candida glabrata. Y. lipolytica is a dimorphic yeast and has good capacities to secrete proteins. The translocation of nascent protein through the endoplasmic reticulum membrane was well studied in Y. lipolytica and is largely co-translational as in the mammalian protein secretion pathway. Results We identified S. cerevisiae proteins involved in vesicular secretion and these protein sequences were used for the BLAST searches against Génolevures protein database (Y. lipolytica, C. glabrata, K. lactis and D. hansenii. These proteins are well conserved between these yeasts and Saccharomyces cerevisiae. We note several specificities of Y. lipolytica which may be related to its good protein secretion capacities and to its dimorphic aspect. An expansion of the Y. lipolytica Rab protein family was observed with autoBLAST and the Rab2- and Rab4-related members were identified with BLAST against NCBI protein database. An expansion of this family is also found in filamentous fungi and may reflect the greater complexity of the Y. lipolytica secretion pathway. The Rab4p-related protein may play a role in membrane recycling as rab4 deleted strain shows a modification of colony morphology, dimorphic transition and permeability. Similarly, we find three copies of the gene (SSO encoding the plasma membrane SNARE protein. Quantification of the percentages of proteins with the greatest homology between S. cerevisiae, Y. lipolytica and animal homologues involved in vesicular

  10. Yeast Biodiversity from DOQ Priorat Uninoculated Fermentations.

    Science.gov (United States)

    Padilla, Beatriz; García-Fernández, David; González, Beatriz; Izidoro, Iara; Esteve-Zarzoso, Braulio; Beltran, Gemma; Mas, Albert

    2016-01-01

    Climate, soil, and grape varieties are the primary characteristics of terroir and lead to the definition of various appellations of origin. However, the microbiota associated with grapes are also affected by these conditions and can leave a footprint in a wine that will be part of the characteristics of terroir. Thus, a description of the yeast microbiota within a vineyard is of interest not only to provide a better understanding of the winemaking process, but also to understand the source of microorganisms that maintain a microbial footprint in wine from the examined vineyard. In this study, two typical grape varieties, Grenache and Carignan, have been sampled from four different vineyards in the DOQ Priorat winegrowing region. Afterward, eight spontaneous alcoholic fermentations containing only grapes from one sampling point and of one variety were conducted at laboratory scale. The fermentation kinetics and yeast population dynamics within each fermentation experiment were evaluated. Yeast identification was performed by RFLP-PCR of the 5.8S-ITS region and by sequencing D1/D2 of the 26S rRNA gene of the isolates. The fermentation kinetics did not indicate clear differences between the two varieties of grapes or among vineyards. Approximately 1,400 isolates were identified, exhibiting high species richness in some fermentations. Of all the isolates studied, approximately 60% belong to the genus Hanseniaspora, 16% to Saccharomyces, and 11% to Candida. Other minor genera, such as Hansenula, Issatchenkia, Kluyveromyces, Saccharomycodes, and Zygosaccharomyces, were also found. The distribution of the identified yeast throughout the fermentation process was studied, and Saccharomyces cerevisiae was found to be present mainly at the end of the fermentation process, while Aureobasidium pullulans was isolated primarily during the first days of fermentation in three of the eight spontaneous fermentations. This work highlights the complexity and diversity of the vineyard

  11. Chemical signaling and insect attraction is a conserved trait in yeasts.

    Science.gov (United States)

    Becher, Paul G; Hagman, Arne; Verschut, Vasiliki; Chakraborty, Amrita; Rozpędowska, Elżbieta; Lebreton, Sébastien; Bengtsson, Marie; Flick, Gerhard; Witzgall, Peter; Piškur, Jure

    2018-03-01

    Yeast volatiles attract insects, which apparently is of mutual benefit, for both yeasts and insects. However, it is unknown whether biosynthesis of metabolites that attract insects is a basic and general trait, or if it is specific for yeasts that live in close association with insects. Our goal was to study chemical insect attractants produced by yeasts that span more than 250 million years of evolutionary history and vastly differ in their metabolism and lifestyle. We bioassayed attraction of the vinegar fly Drosophila melanogaster to odors of phylogenetically and ecologically distinct yeasts grown under controlled conditions. Baker's yeast Saccharomyces cerevisiae , the insect-associated species Candida californica , Pichia kluyveri and Metschnikowia andauensis , wine yeast Dekkera bruxellensis , milk yeast Kluyveromyces lactis , the vertebrate pathogens Candida albicans and Candida glabrata , and oleophilic Yarrowia lipolytica were screened for fly attraction in a wind tunnel. Yeast headspace was chemically analyzed, and co-occurrence of insect attractants in yeasts and flowering plants was investigated through a database search. In yeasts with known genomes, we investigated the occurrence of genes involved in the synthesis of key aroma compounds. Flies were attracted to all nine yeasts studied. The behavioral response to baker's yeast was independent of its growth stage. In addition to Drosophila , we tested the basal hexapod Folsomia candida (Collembola) in a Y-tube assay to the most ancient yeast, Y. lipolytica, which proved that early yeast signals also function on clades older than neopteran insects. Behavioral and chemical data and a search for selected genes of volatile metabolites underline that biosynthesis of chemical signals is found throughout the yeast clade and has been conserved during the evolution of yeast lifestyles. Literature and database reviews corroborate that yeast signals mediate mutualistic interactions between insects and yeasts

  12. Controlled production of Camembert-type cheeses. Part I: Microbiological and physicochemical evolutions.

    Science.gov (United States)

    Leclercq-Perlat, Marie-Noëlle; Buono, Frédéric; Lambert, Denis; Latrille, Eric; Spinnler, Henry-Eric; Corrieu, Georges

    2004-08-01

    A holistic approach of a mould cheese ripening is presented. The objective was to establish relationships between the different microbiological and biochemical changes during cheese ripening. Model cheeses were prepared from pasteurized milk inoculated with Kluyveromyces lactis, Geotrichum candidum, Penicillium camemberti and Brevibacterium linens under aseptic conditions. Two cheese-making trials with efficient control of environmental parameters were carried out and showed similar ripening characteristics. K. lactis grew rapidly between days 1 and 6 (generation time around 48 h). G. candidum grew exponentially between days 4 and 10 (generation time around 4.6 d). Brevi. linens also grew exponentially but after day 6 when Pen. camemberti mycelium began developing and the pH of the rind was close to 7. Its exponential growth presented 3 phases in relation to carbon and nitrogen substrate availability. Concentrations of Pen. camemberti mycelium were not followed by viable cell count but they were evaluated visually. The viable microorganism concentrations were well correlated with the carbon substrate concentrations in the core and in the rind. The lactose concentrations were negligible after 10 d ripening, and changes in lactate quantities were correlated with fungi flora. The pH of the inner part depended on NH3. Surface pH was significantly related to NH3 concentration and to fungi growth. The acid-soluble nitrogen (ASN) and non-protein nitrogen (NPN) indexes and NH3 concentrations of the rind were low until day 6, and then increased rapidly to follow the fungi concentrations until day 45. The ASN and NPN indexes and NH3 concentrations in the core were lower than in the rind and they showed the same evolution. G. candidum and Pen. camemberti populations have a major effect on proteolysis; nevertheless, K. lactis and Brevi. linens cell lysis also had an impact on proteolysis. Viable cell counts of K. lactis, G. candidum, Pen. camemberti and Brevi. linens were

  13. Divergent Evolution of the Transcriptional Network Controlled by Snf1-Interacting Protein Sip4 in Budding Yeasts.

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    Constance Mehlgarten

    Full Text Available Cellular responses to starvation are of ancient origin since nutrient limitation has always been a common challenge to the stability of living systems. Hence, signaling molecules involved in sensing or transducing information about limiting metabolites are highly conserved, whereas transcription factors and the genes they regulate have diverged. In eukaryotes the AMP-activated protein kinase (AMPK functions as a central regulator of cellular energy homeostasis. The yeast AMPK ortholog SNF1 controls the transcriptional network that counteracts carbon starvation conditions by regulating a set of transcription factors. Among those Cat8 and Sip4 have overlapping DNA-binding specificity for so-called carbon source responsive elements and induce target genes upon SNF1 activation. To analyze the evolution of the Cat8-Sip4 controlled transcriptional network we have compared the response to carbon limitation of Saccharomyces cerevisiae to that of Kluyveromyces lactis. In high glucose, S. cerevisiae displays tumor cell-like aerobic fermentation and repression of respiration (Crabtree-positive while K. lactis has a respiratory-fermentative life-style, respiration being regulated by oxygen availability (Crabtree-negative, which is typical for many yeasts and for differentiated higher cells. We demonstrate divergent evolution of the Cat8-Sip4 network and present evidence that a role of Sip4 in controlling anabolic metabolism has been lost in the Saccharomyces lineage. We find that in K. lactis, but not in S. cerevisiae, the Sip4 protein plays an essential role in C2 carbon assimilation including induction of the glyoxylate cycle and the carnitine shuttle genes. Induction of KlSIP4 gene expression by KlCat8 is essential under these growth conditions and a primary function of KlCat8. Both KlCat8 and KlSip4 are involved in the regulation of lactose metabolism in K. lactis. In chromatin-immunoprecipitation experiments we demonstrate binding of both, KlSip4 and

  14. Microbial production of lactase

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, M; Ishizuka, S; Fujino, S

    1978-03-06

    A novel lactase (1) is produced by aerobic culture of Kluyveromyces lactis 013-2 (FERMiP 3513). Thus, the microbe was aerobically cultured at 30/sup 0/ for 24 h on a liquid medium (pH 5.5) containing corn steep liquor 7 and lactose 2%. The cells (1.5 kg) were washed with water, mixed with toluol 80 mL and 0.05 M phosphate buffer (pH 7.0) 1.5 L, and autolyzed at 30/sup 0/ for 15 h. The autolyzate was centrifuged, the supernatant (2.5 L) was mixed with an equal volume of cold Me/sub 2/CO, the resulting precipitate was dissolved in 600 mL water, and the solution was mixed with protamine and the resulting precipitate was removed to yield 500 mL enzymes solution of 2000 units/mL. The enzyme solution was dialyzed against 0.01 M phosphate buffer (pH 7.0) 1.5 L, and autolyzed at 30/sup 0/ for 15 h. The autolyzate was centrifuged, the supernatant (2.5 L) was mixed with an equal volume of cold Me/sub 2/CO, the resulting precipitate was dissolved in 600 mL water, and the solution was mixed with protamine and the resulting precipitate was removed to yield 500 mL enzymes solution of 2000 units/mL. The enzyme solution was dialyzed against 0.01 M phosphate buffer (pH 7.9) containing 0.0001 M MnSO/sub 4/, and subjected to column chromatography on DEAE-Cellulose to separate 1-A 3.6 and 1-B 1.6 g, respectively. The enzyme had optimum pH and temperature at pH 6.0 to 6.5 and 40 to 50/sup 0/, respectively. It was stable at pH 6 to 8 and was inactivated at 55/sup 0/. It was inhibited with heavy metal salts, p-chloromercuribenzoate, and EDTA and activated with Mn/sup 2 +/, Mg/sup 2 +/, CO/sup 2 +/, Ni/sup 2 +/, K/sup +/ and Na/sup +/.

  15. Evolutionary Diversification of Alanine Transaminases in Yeast: Catabolic Specialization and Biosynthetic Redundancy

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    Ximena Escalera-Fanjul

    2017-06-01

    Full Text Available Gene duplication is one of the major evolutionary mechanisms providing raw material for the generation of genes with new or modified functions. The yeast Saccharomyces cerevisiae originated after an allopolyploidization event, which involved mating between two different ancestral yeast species. ScALT1 and ScALT2 codify proteins with 65% identity, which were proposed to be paralogous alanine transaminases. Further analysis of their physiological role showed that while ScALT1 encodes an alanine transaminase which constitutes the main pathway for alanine biosynthesis and the sole pathway for alanine catabolism, ScAlt2 does not display alanine transaminase activity and is not involved in alanine metabolism. Moreover, phylogenetic studies have suggested that ScALT1 and ScALT2 come from each one of the two parental strains which gave rise to the ancestral hybrid. The present work has been aimed to the understanding of the properties of the ancestral type Lacchancea kluyveri LkALT1 and Kluyveromyces lactis KlALT1, alanine transaminases in order to better understand the ScALT1 and ScALT2 evolutionary history. These ancestral -type species were chosen since they harbor ALT1 genes, which are related to ScALT2. Presented results show that, although LkALT1 and KlALT1 constitute ScALT1 orthologous genes, encoding alanine transaminases, both yeasts display LkAlt1 and KlAlt1 independent alanine transaminase activity and additional unidentified alanine biosynthetic and catabolic pathway(s. Furthermore, phenotypic analysis of null mutants uncovered the fact that KlAlt1 and LkAlt1 have an additional role, not related to alanine metabolism but is necessary to achieve wild type growth rate. Our study shows that the ancestral alanine transaminase function has been retained by the ScALT1 encoded enzyme, which has specialized its catabolic character, while losing the alanine independent role observed in the ancestral type enzymes. The fact that ScAlt2 conserves 64

  16. A novel cold-active β-D-galactosidase from the Paracoccus sp. 32d - gene cloning, purification and characterization

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    Wierzbicka-Woś Anna

    2011-12-01

    Full Text Available Abstract Background β-D-Galactosidases (EC 3.2.1.23 catalyze the hydrolysis of terminal non-reducing β-D-galactose residues in β-D-galactosides. Cold-active β-D-galactosidases have recently become a focus of attention of researchers and dairy product manufactures owing to theirs ability to: (i eliminate of lactose from refrigerated milk for people afflicted with lactose intolerance, (ii convert lactose to glucose and galactose which increase the sweetness of milk and decreases its hydroscopicity, and (iii eliminate lactose from dairy industry pollutants associated with environmental problems. Moreover, in contrast to commercially available mesophilic β-D-galactosidase from Kluyveromyces lactis the cold-active counterparts could make it possible both to reduce the risk of mesophiles contamination and save energy during the industrial process connected with lactose hydrolysis. Results A genomic DNA library was constructed from soil bacterium Paracoccus sp. 32d. Through screening of the genomic DNA library on LB agar plates supplemented with X-Gal, a novel gene encoding a cold-active β-D-galactosidase was isolated. The in silico analysis of the enzyme amino acid sequence revealed that the β-D-galactosidase Paracoccus sp. 32d is a novel member of Glycoside Hydrolase Family 2. However, owing to the lack of a BGal_small_N domain, the domain characteristic for the LacZ enzymes of the GH2 family, it was decided to call the enzyme under study 'BgaL'. The bgaL gene was cloned and expressed in Escherichia coli using the pBAD Expression System. The purified recombinant BgaL consists of two identical subunits with a combined molecular weight of about 160 kDa. The BgaL was optimally active at 40°C and pH 7.5. Moreover, BgaL was able to hydrolyze both lactose and o-nitrophenyl-β-D-galactopyranoside at 10°C with Km values of 2.94 and 1.17 mM and kcat values 43.23 and 71.81 s-1, respectively. One U of the recombinant BgaL would thus be capable

  17. Biochemical conversions of lignocellulosic biomass for sustainable fuel-ethanol production in the upper Midwest

    Science.gov (United States)

    Brodeur-Campbell, Michael J.

    species results. Chapter 4 is an evaluation of the potential for producing Trichoderma reesei cellulose hydrolases in the Kluyveromyces lactis yeast expression system. The exoglucanases Cel6A and Cel7A, and the endoglucanase Cel7B were inserted separately into the K. lactis and the enzymes were analyzed for activity on various substrates. Recombinant Cel7B was found to be active on carboxymethyl cellulose and Avicel powdered cellulose substrates. Recombinant Cel6A was also found to be active on Avicel. Recombinant Cel7A was produced, but no enzymatic activity was detected on any substrate. Chapter 5 presents a new method for enzyme improvement studies using enzyme co-expression and yeast growth rate measurements as a potential high-throughput expression and screening system in K. lactis yeast. Two different K. lactis strains were evaluated for their usefulness in growth screening studies, one wild-type strain and one strain which has had the main galactose metabolic pathway disabled. Sequential transformation and co-expression of the exoglucanase Cel6A and endoglucanase Cel7B was performed, and improved hydrolysis rates on Avicel were detectable in the cell culture supernatant. Future work should focus on hydrolysis of natural substrates, developing the growth screening method, and utilizing the K. lactis expression system for directed evolution of enzymes.

  18. Catabolism of biomass-derived sugars in fungi and metabolic engineering as a tool for organic acid production

    Energy Technology Data Exchange (ETDEWEB)

    Koivistoinen, O.

    2013-11-01

    gene ladB was identified and the deletion of the gene resulted in growth arrest on galactitol indicating that the enzyme is an essential part of the oxido-reductive galactose pathway in fungi. The last step of this pathway converts D-sorbitol to D-fructose by sorbitol dehydrogenase encoded by sdhA gene. Sorbitol dehydrogenase was found to be a medium chain dehydrogenase and transcription analysis suggested that the enzyme is involved in D-galactose and D-sorbitol catabolism. The thesis also demonstrates how the understanding of cell metabolism can be used to engineer yeast to produce glycolic acid. Glycolic acid is a chemical, which can be used for example in the cosmetic industry and as a precursor for biopolymers. Currently, glycolic acid is produced by chemical synthesis in a process requiring toxic formaldehyde and fossil fuels. Thus, a biochemical production route would be preferable from a sustainability point of view. Yeasts do not produce glycolic acid under normal conditions but it is a desired production host for acid production because of its natural tolerance to low pH conditions. As a proof of concept, pure model substrates, e.g. D-xylose and ethanol, were used as starting materials for glycolic acid production but the knowledge can be further applied to an expanded substrate range such as biomass derived sugars. Already the introduction of a heterologous glyoxylate reductase gene resulted in glycolic acid production in the yeasts S. cerevisiae and Kluyveromyces lactis. Further modifications of the glyoxylate cycle increased the production of glycolic acid and it was successfully produced in bioreactor cultivation. The challenge of biotechnology is to produce high value products from cheap raw materials in an economically feasible way. This thesis gives more basic understanding to the topic in the form of new information regarding L-rhamnose and D-galactose metabolism in eukaryotic microbes as well as provides an example on how cell metabolism can be