WorldWideScience

Sample records for acid producing saccharomyces

  1. Candida zemplinina can reduce acetic acid produced by Saccharomyces cerevisiae in sweet wine fermentations.

    Science.gov (United States)

    Rantsiou, Kalliopi; Dolci, Paola; Giacosa, Simone; Torchio, Fabrizio; Tofalo, Rosanna; Torriani, Sandra; Suzzi, Giovanna; Rolle, Luca; Cocolin, Luca

    2012-03-01

    In this study we investigated the possibility of using Candida zemplinina, as a partner of Saccharomyces cerevisiae, in mixed fermentations of must with a high sugar content, in order to reduce its acetic acid production. Thirty-five C. zemplinina strains, which were isolated from different geographic regions, were molecularly characterized, and their fermentation performances were determined. Five genetically different strains were selected for mixed fermentations with S. cerevisiae. Two types of inoculation were carried out: coinoculation and sequential inoculation. A balance between the two species was generally observed for the first 6 days, after which the levels of C. zemplinina started to decrease. Relevant differences were observed concerning the consumption of sugars, the ethanol and glycerol content, and acetic acid production, depending on which strain was used and which type of inoculation was performed. Sequential inoculation led to the reduction of about half of the acetic acid content compared to the pure S. cerevisiae fermentation, but the ethanol and glycerol amounts were also low. A coinoculation with selected combinations of S. cerevisiae and C. zemplinina resulted in a decrease of ~0.3 g of acetic acid/liter, while maintaining high ethanol and glycerol levels. This study demonstrates that mixed S. cerevisiae and C. zemplinina fermentation could be applied in sweet wine fermentation to reduce the production of acetic acid, connected to the S. cerevisiae osmotic stress response.

  2. Identification of a novel C22-∆4-producing docosahexaenoic acid (DHA) specific polyunsaturated fatty acid desaturase gene from Isochrysis galbana and its expression in Saccharomyces cerevisiae.

    Science.gov (United States)

    Shi, Tonglei; Yu, Aiqun; Li, Ming; Ou, Xiuyuan; Xing, Laijun; Li, Mingchun

    2012-12-01

    Isochrysis galbana, produces long chain polyunsaturated fatty acids including docosahexaenoic acid (DHA, 22:6n-3). A novel gene (IgFAD4-2), encoding a C22-∆4 polyunsaturated fatty acid specific desaturase, has been isolated and characterized from I. galbana. A full-length cDNA of 1,302 bp was cloned by LA-PCR technique. The IgFAD4-2 encoded a protein of 433 amino acids that shares 78 % identity with a previously reported ∆4-desaturase (IgFAD4-1) from I. galbana. The function of IgFAD4-2 was deduced by its heterologous expression in Saccharomyces cerevisiae, which then desaturated docosapentaenoic acid (DPA, 22:5n-3) to DHA. The conversion ratio of DPA to DHA was 34 %, which is higher than other ∆4-desaturases cloned from algae. However, IgFAD4-2 did not catalyze the desaturation or elongation reactions with other fatty acids. These results confirm that IgFAD4-2 has C22-∆4-PUFAs-specific desaturase activity.

  3. Different response to acetic acid stress in Saccharomyces cerevisiae wild-type and l-ascorbic acid-producing strains.

    Science.gov (United States)

    Martani, Francesca; Fossati, Tiziana; Posteri, Riccardo; Signori, Lorenzo; Porro, Danilo; Branduardi, Paola

    2013-09-01

    Biotechnological processes are of increasing significance for industrial production of fine and bulk chemicals, including biofuels. Unfortunately, under operative conditions microorganisms meet multiple stresses, such as non-optimal pH, temperature, oxygenation and osmotic stress. Moreover, they have to face inhibitory compounds released during the pretreatment of lignocellulosic biomasses, which constitute the preferential substrate for second-generation processes. Inhibitors include furan derivatives, phenolic compounds and weak organic acids, among which acetic acid is one of the most abundant and detrimental for cells. They impair cellular metabolism and growth, reducing the productivity of the process: therefore, the development of robust cell factories with improved production rates and resistance is of crucial importance. Here we show that a yeast strain engineered to endogenously produce vitamin C exhibits an increased tolerance compared to the parental strain when exposed to acetic acid at moderately toxic concentrations, measured as viability on plates. Starting from this evidence, we investigated more deeply: (a) the nature and levels of reactive oxygen species (ROS); (b) the activation of enzymes that act directly as detoxifiers of reactive oxygen species, such as superoxide dismutase (SOD) and catalase, in parental and engineered strains during acetic acid stress. The data indicate that the engineered strain can better recover from stress by limiting ROS accumulation, independently from SOD activation. The engineered yeast can be proposed as a model for further investigating direct and indirect mechanism(s) by which an antioxidant can rescue cells from organic acid damage; moreover, these studies will possibly provide additional targets for further strain improvements.

  4. Succinic acid in levels produced by yeast (Saccharomyces cerevisiae) during fermentation strongly impacts wheat bread dough properties.

    Science.gov (United States)

    Jayaram, Vinay B; Cuyvers, Sven; Verstrepen, Kevin J; Delcour, Jan A; Courtin, Christophe M

    2014-05-15

    Succinic acid (SA) was recently shown to be the major pH determining metabolite produced by yeast during straight-dough fermentation (Jayaram et al., 2013), reaching levels as high as 1.6 mmol/100 g of flour. Here, the impact of such levels of SA (0.8, 1.6 and 2.4 mmol/100 g flour) on yeastless dough properties was investigated. SA decreased the development time and stability of dough significantly. Uniaxial extension tests showed a consistent decrease in dough extensibility upon increasing SA addition. Upon biaxial extension in the presence of 2.4 mmol SA/100 g flour, a dough extensibility decrease of 47-65% and a dough strength increase of 25-40% were seen. While the SA solvent retention capacity of flour increased with increasing SA concentration in the solvent, gluten agglomeration decreased with gluten yield reductions of over 50%. The results suggest that SA leads to swelling and unfolding of gluten proteins, thereby increasing their interaction potential and dough strength, but simultaneously increasing intermolecular electrostatic repulsive forces. These phenomena lead to the reported changes in dough properties. Together, our results establish SA as an important yeast metabolite for dough rheology.

  5. Influence of organic acids and organochlorinated insecticides on metabolism of Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Pejin Dušanka J.

    2005-01-01

    Full Text Available Saccharomyces cerevisiae is exposed to different stress factors during the production: osmotic, temperature, oxidative. The response to these stresses is the adaptive mechanism of cells. The raw materials Saccharomyces cerevisiae is produced from, contain metabolism products of present microorganisms and protective agents used during the growth of sugar beet for example the influence of acetic and butyric acid and organochlorinated insecticides, lindan and heptachlor, on the metabolism of Saccharomyces cerevisiae was investigated and presented in this work. The mentioned compounds affect negatively the specific growth rate, yield, content of proteins, phosphorus, total ribonucleic acids. These compounds influence the increase of trechalose and glycogen content in the Saccharomyces cerevisiae cells.

  6. Overproduction of fatty acids in engineered Saccharomyces cerevisiae.

    Science.gov (United States)

    Li, Xiaowei; Guo, Daoyi; Cheng, Yongbo; Zhu, Fayin; Deng, Zixin; Liu, Tiangang

    2014-09-01

    The long hydrocarbon fatty acyl chain is energy rich, making it an ideal precursor for liquid transportation fuels and high-value oleo chemicals. As Saccharomyces cerevisiae has many advantages for industrial production compared to Escherichia coli. Here, we attempted to engineer Saccharomyces cerevisiae for overproduction of fatty acids. First, disruption of the beta-oxidation pathway, elimination of the acyl-CoA synthetases, overexpression of different thioesterases and acetyl-CoA carboxylase ACC1, and engineering the supply of precursor acetyl-CoA. The engineered strain XL122 produced more than 120 mg/L of fatty acids. In parallel, we inactivated ADH1, the dominant gene for ethanol production, to redirect the metabolic flux to fatty acids synthesis. The engineered strain DG005 produced about 140 mg/L fatty acids. Additionally, Acetyl-CoA carboxylase was identified as a critical bottleneck of fatty acids synthesis in S. cerevisiae with a cell-free system. However, overexpression of ACC1 has little effect on fatty acids biosynthesis. As it has been reported that phosphorylation of ACC1 may influent its activity, so phosphorylation sites of ACC1 were further identified. Although the regulatory mechanisms remain unclear, our results provide rationale for future studies to target this critical step. All these efforts, particularly the discovery of the limiting step are critical for developing a "cell factory" for the overproduction of fatty acids by using type I fatty acids synthase in yeast or other fungi.

  7. [Construction and fermentation control of reductive TCA pathway for malic acid production in Saccharomyces cerevisiae].

    Science.gov (United States)

    Yan, Daojiang; Wang, Caixia; Zhou, Jiemin; Liu, Yilan; Yang, Maohua; Xing, Jianmin

    2013-10-01

    Malic acid is widely used in food, and chemical industries. Through overexpressing pyruvate carboxylase and malate dehydrogenase in pdc1-deficient Saccharomyces cerevisiae, malic acid was successfully produced through the reductive TCA pathway. No malic acid was detected in wild type Saccharomyces cerevisiae, however, 45 mmol/L malic acid was produced in engineered strain, and the concentration of byproduct ethanol also reduced by 18%. The production of malic acid enhanced 6% by increasing the concentration of Ca2+. In addition, the final concentration reached 52.5 mmol/L malic acid by addition of biotin. The increasing is almost 16% higher than that of the original strain.

  8. Triacetic acid lactone production from Saccharomyces cerevisiae

    Science.gov (United States)

    Triacetic acid lactone (TAL) is a potential platform chemical produced from acetyl-CoA and malonyl-CoA by the Gerbera hybrida 2-pyrone synthase (2PS) gene. Studies are ongoing to optimize production, purification, and chemical modification of TAL, which can be used to create the commercial chemicals...

  9. Malic acid production by Saccharomyces cerevisiae: engineering of pyruvate carbosylation, oxaloacetate reduction and malate export

    NARCIS (Netherlands)

    Zelle, R.M.; Hulster, de E.; Winden, van W.A.; Waard, de P.; Dijkema, C.; Winkler, A.A.; Geertman, J.M.A.

    2008-01-01

    Malic acid is a potential biomass-derivable "building block" for chemical synthesis. Since wild-type Saccharomyces cerevisiae strains produce only low levels of malate, metabolic engineering is required to achieve efficient malate production with this yeast. A promising pathway for malate production

  10. Malic Acid Production by Saccharomyces cerevisiae: Engineering of Pyruvate Carboxylation, Oxaloacetate Reduction, and Malate Export

    NARCIS (Netherlands)

    Zelle, R.M.; De Hulster, E.; Van Winden, W.A.; De Waard, P.; Dijkema, C.; Winkler, A.A.; Geertman, J.M.; Van Dijken, J.P.; Pronk, J.T.; Van Maris, A.J.A.

    2008-01-01

    Malic acid is a potential biomass-derivable "building block" for chemical synthesis. Since wild-type Saccharomyces cerevisiae strains produce only low levels of malate, metabolic engineering is required to achieve efficient malate production with this yeast. A promising pathway for malate production

  11. Isolation of a novel C18-Δ9 polyunsaturated fatty acid specific elongase gene from DHA-producing Isochrysis galbana H29 and its use for the reconstitution of the alternative Δ8 pathway in Saccharomyces cerevisiae.

    Science.gov (United States)

    Li, Ming; Ou, Xiuyuan; Yang, Xiangdong; Guo, Dongquan; Qian, Xueyan; Xing, Laijun; Li, Mingchun

    2011-09-01

    A novel gene (IgASE2) encoding a C18-Δ9 polyunsaturated fatty acids specific (C18-Δ9-PUFAs-specific) elongase was isolated and characterized from DHA-rich microalga, Isochrysis galbana H29. The IgASE2 gene was 1,653 bp in length, contained a 786 bp ORF encoding a protein of 261 amino acids that shared 87% identity with Δ9 elongase, IgASE1, and possessed a 44 bp 5'-untranslated region (5'-UTR) and a 823 bp 3'-untranslated region (3'-UTR). IgASE2, by its heterologous expression in Saccharomyces cerevisiae, elongated linoleic acid (LA, 18:2n-6) and α-linolenic (ALA, 18:3n-3) to eicosadienoic acid (EDA, 20:2n-6) and eicosatrienoic acid (ETrA, 20:3n-3), respectively. The conversions of LA to EDA and ALA to ETrA were 57.6 and 56.1%, respectively. Co-expression of this elongase with Δ8 desaturase required for the synthesis of C20-polyunsaturated fatty acids resulted in the accumulation of dihomo-γ-linolenic acid (20:3n-6) from LA and eicosatetraenoic acid (20:4n-6) from ALA. These results demonstrated that IgASE2 exhibited C18-Δ9-PUFAs-specific elongase activity and the alternative Δ8 pathway was reconstituted.

  12. Capturing of the monoterpene olefin limonene produced in Saccharomyces cerevisiae.

    Science.gov (United States)

    Jongedijk, Esmer; Cankar, Katarina; Ranzijn, Jorn; van der Krol, Sander; Bouwmeester, Harro; Beekwilder, Jules

    2015-01-01

    Monoterpene olefins such as limonene are plant compounds with applications as flavouring and fragrance agents, as solvents and potentially also in polymer and fuel chemistry. We engineered baker's yeast Saccharomyces cerevisiae to express a (-)-limonene synthase from Perilla frutescens and a (+)-limonene synthase from Citrus limon. Both proteins were expressed either with their native plastid targeting signal or in a truncated form in which the plastidial sorting signal was removed. The yeast host strain for expression was AE9 K197G, which expresses a mutant Erg20 enzyme. This enzyme catalyses the formation of geranyl diphosphate, which is the precursor for monoterpenes. Several methods were tested to capture limonene produced by the yeast. Extraction from the culture medium by pentane, or by the addition of CaCl2 followed by solid-phase micro-extraction, did not lead to detectable limonene, indicating that limonene is rapidly lost from the culture medium. Volatile terpenes such as limonene may also be trapped in a dodecane phase added to the medium during fermentation. This method resulted in recovery of 0.028 mg/l (+)-limonene and 0.060 mg/l (-)-limonene in strains using the truncated Citrus and Perilla synthases, respectively. Trapping the headspace during culture of the limonene synthase-expressing strains resulted in higher titres, at 0.12 mg/l (+)-limonene and 0.49 mg/l (-)-limonene. These results show that the volatile properties of the olefins produced require specific methods for efficient recovery of these molecules from biotechnological production systems.

  13. Industrial Systems Biology of Saccharomyces cerevisiae Enables Novel Succinic Acid Cell Factory

    DEFF Research Database (Denmark)

    Otero, José Manuel; Cimini, Donatella; Patil, Kiran Raosaheb

    2013-01-01

    Saccharomyces cerevisiae is the most well characterized eukaryote, the preferred microbial cell factory for the largest industrial biotechnology product (bioethanol), and a robust commerically compatible scaffold to be exploitted for diverse chemical production. Succinic acid is a highly sought......-direction of carbon fluxes in S. cerevisiae, and hence show proof of concept that this is a potentially attractive cell factory for over-producing different platform chemicals....

  14. Metabolic engineering of Saccharomyces cerevisiae to improve succinic acid production based on metabolic profiling.

    Science.gov (United States)

    Ito, Yuma; Hirasawa, Takashi; Shimizu, Hiroshi

    2014-01-01

    We performed metabolic engineering on the budding yeast Saccharomyces cerevisiae for enhanced production of succinic acid. Aerobic succinic acid production in S. cerevisiae was achieved by disrupting the SDH1 and SDH2 genes, which encode the catalytic subunits of succinic acid dehydrogenase. Increased succinic acid production was achieved by eliminating the ethanol biosynthesis pathways. Metabolic profiling analysis revealed that succinic acid accumulated intracellularly following disruption of the SDH1 and SDH2 genes, which suggests that enhancing the export of intracellular succinic acid outside of cells increases succinic acid production in S. cerevisiae. The mae1 gene encoding the Schizosaccharomyces pombe malic acid transporter was introduced into S. cerevisiae, and as a result, succinic acid production was successfully improved. Metabolic profiling analysis is useful in producing chemicals for metabolic engineering of microorganisms.

  15. Genetic dissection of acetic acid tolerance in Saccharomyces cerevisiae.

    Science.gov (United States)

    Geng, Peng; Xiao, Yin; Hu, Yun; Sun, Haiye; Xue, Wei; Zhang, Liang; Shi, Gui-Yang

    2016-09-01

    Dissection of the hereditary architecture underlying Saccharomyces cerevisiae tolerance to acetic acid is essential for ethanol fermentation. In this work, a genomics approach was used to dissect hereditary variations in acetic acid tolerance between two phenotypically different strains. A total of 160 segregants derived from these two strains were obtained. Phenotypic analysis indicated that the acetic acid tolerance displayed a normal distribution in these segregants, and suggested that the acetic acid tolerant traits were controlled by multiple quantitative trait loci (QTLs). Thus, 220 SSR markers covering the whole genome were used to detect QTLs of acetic acid tolerant traits. As a result, three QTLs were located on chromosomes 9, 12, and 16, respectively, which explained 38.8-65.9 % of the range of phenotypic variation. Furthermore, twelve genes of the candidates fell into the three QTL regions by integrating the QTL analysis with candidates of acetic acid tolerant genes. These results provided a novel avenue to obtain more robust strains.

  16. ORGANIC ACIDS CONCENTRATION IN WINE STOCKS AFTER Saccharomyces cerevisiae FERMENTATION

    Directory of Open Access Journals (Sweden)

    V. N. Bayraktar

    2013-04-01

    Full Text Available The biochemical constituents in wine stocks that influence the flavor and quality of wine are investigated in the paper. The tested parameters consist of volume fraction of ethanol, residual sugar, phenolic compounds, tartaric, malic, citric, lactic, acetic acids, titratable acidity and volatile acids. The wine stocks that were received from white and red grape varieties Tairov`s selection were tested. There was a correlation between titratable acidity and volatile acids in the wine stocks from white and red grape varieties. High correlation was also found between lactic and acetic acids, between volatile acids, acetic acid and sugar. It was determined that wine stocks with a high concentration of ethanol originated from those yeast strains of Saccharomyces cerevisiae, in a fermented grape must of high speed of enzyme activity. The taste of wine stocks correlated with the ratio of tartaric to malic acid. Analysis showed significant differences between the varieties of white and red wine stocks in concentrations of organic acids, phenolic compounds, residual sugar, and volume fraction of ethanol. Positive correlation was indicated for both studied groups for volatile acids and acetic acid, tartaric, malic, lactic acids and total sugar. Prospective yeast cultures with high productivity of alcohol (ethanol were selected for winemaking biotechnology.

  17. Overexpression of ESBP6 improves lactic acid resistance and production in Saccharomyces cerevisiae.

    Science.gov (United States)

    Sugiyama, Minetaka; Akase, Shin-Pei; Nakanishi, Ryota; Kaneko, Yoshinobu; Harashima, Satoshi

    2016-10-01

    Polylactic acid plastics are receiving increasing attention for the control of atmospheric CO2 emissions. Lactic acid, the building block for polylactic acid, is produced by fermentation technology from renewable carbon sources. The yeast Saccharomyces cerevisiae, harboring the lactate dehydrogenases gene (LDH), produces lactic acid at a large scale due to its strong acid resistance, to its simple nutritional requirements and to its ease of genetic engineering. Since improvement of lactic acid resistance is correlated with an increase of lactic acid production under non-neutralizing condition, we isolated a novel gene that enhances lactic acid resistance using a multi-copy yeast genomic DNA library. In this study, we identified the ESBP6 gene, which increases lactic acid resistance when overexpressed and which encodes a protein with similarity to monocarboxylate permeases. Although ESBP6 was not induced in response to lactic acid stress, it caused weak but reproducible sensitivity to lactic acid when disrupted. Furthermore, intracellular pH in the ESBP6 overexpressing strain was higher than that in the wild-type strain under lactic acid stressed condition, suggesting that Esbp6 plays some roles in lactic acid adaptation response. The ESBP6 overexpressing strain carrying the LDH gene induced 20% increase in lactic acid production compared with the wild-type strain carrying the LDH gene under non-neutralizing conditions. These results indicate that overexpression of ESBP6 provides a novel and useful tool to improve lactic acid resistance and lactic acid production in yeast.

  18. Understanding the 3-hydroxypropionic acid tolerance mechanism in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Kildegaard, Kanchana Rueksomtawin; Juncker, Agnieszka; Hallstrom, Bjorn;

    2013-01-01

    a sustainable alternative for production of acrylic acid from renewable feedstocks. We are establishing Saccharomyces cerevisiae as an alternative host for 3HP production. However, 3HP also inhibits yeast grow th at level well below what is desired for commercial applications. Therefore, we are aiming...... to improve 3HP tolerance in S. cerevisiae by applying adaptive evolution approach. We have generated yeast strains with sign ificantly improved capacity for tolerating 3HP when compared to the wild-type. We will present physiolo gical characterization, genome re-sequencing, and transcriptome analysis...

  19. Functional expression in frog oocytes of human ρ1 receptors produced in Saccharomyces cerevisiae

    Science.gov (United States)

    Martínez-Martínez, Alejandro; Reyes-Ruiz, Jorge Mauricio; Martínez-Torres, Ataúlfo; Miledi, Ricardo

    2004-01-01

    The yeast Saccharomyces cerevisiae was engineered to express the ρ1 subunit of the human γ-aminobutyric acid ρ1 (GABAρ1) receptor. RNA that was isolated from several transformed yeast strains produced fully functional GABA receptors in Xenopus oocytes. The GABA currents elicited in the oocytes were fast, nondesensitizing chloride currents; and the order of agonist potency was GABA > β-alanine > glycine. Moreover, the receptors were resistant to bicuculline, strongly antagonized by (1,2,5,6 tetrahydropyridine-4-yl)methylphosphinic acid, and modulated by zinc and lanthanum. Thus, the GABA receptors expressed by the yeast mRNA retained all of the principal characteristics of receptors expressed by cRNA or native retina mRNAs. Western blot assays showed immunoreactivity in yeast plasma membrane preparations, and a ρ1-GFP fusion gene showed mostly intracellular distribution with a faint fluorescence toward the plasma membrane. In situ immunodetection of ρ1 in yeast demonstrated that some receptors reach the plasma membrane. Furthermore, microtransplantation of yeast plasma membranes to frog oocytes resulted in the incorporation of a small number of functional yeast ρ1 receptors into the oocyte plasma membrane. These results show that yeast may be useful to produce complete functional ionotropic receptors suitable for structural analysis. PMID:14704273

  20. Carboxylic Acids Plasma Membrane Transporters in Saccharomyces cerevisiae.

    Science.gov (United States)

    Casal, Margarida; Queirós, Odília; Talaia, Gabriel; Ribas, David; Paiva, Sandra

    2016-01-01

    This chapter covers the functionally characterized plasma membrane carboxylic acids transporters Jen1, Ady2, Fps1 and Pdr12 in the yeast Saccharomyces cerevisiae, addressing also their homologues in other microorganisms, as filamentous fungi and bacteria. Carboxylic acids can either be transported into the cells, to be used as nutrients, or extruded in response to acid stress conditions. The secondary active transporters Jen1 and Ady2 can mediate the uptake of the anionic form of these substrates by a H(+)-symport mechanism. The undissociated form of carboxylic acids is lipid-soluble, crossing the plasma membrane by simple diffusion. Furthermore, acetic acid can also be transported by facilitated diffusion via Fps1 channel. At the cytoplasmic physiological pH, the anionic form of the acid prevails and it can be exported by the Pdr12 pump. This review will highlight the mechanisms involving carboxylic acids transporters, and the way they operate according to the yeast cell response to environmental changes, as carbon source availability, extracellular pH and acid stress conditions.

  1. Engineering and Evolution of Saccharomyces cerevisiae to Produce Biofuels and Chemicals.

    Science.gov (United States)

    Turner, Timothy L; Kim, Heejin; Kong, In Iok; Liu, Jing-Jing; Zhang, Guo-Chang; Jin, Yong-Su

    2016-12-03

    To mitigate global climate change caused partly by the use of fossil fuels, the production of fuels and chemicals from renewable biomass has been attempted. The conversion of various sugars from renewable biomass into biofuels by engineered baker's yeast (Saccharomyces cerevisiae) is one major direction which has grown dramatically in recent years. As well as shifting away from fossil fuels, the production of commodity chemicals by engineered S. cerevisiae has also increased significantly. The traditional approaches of biochemical and metabolic engineering to develop economic bioconversion processes in laboratory and industrial settings have been accelerated by rapid advancements in the areas of yeast genomics, synthetic biology, and systems biology. Together, these innovations have resulted in rapid and efficient manipulation of S. cerevisiae to expand fermentable substrates and diversify value-added products. Here, we discuss recent and major advances in rational (relying on prior experimentally-derived knowledge) and combinatorial (relying on high-throughput screening and genomics) approaches to engineer S. cerevisiae for producing ethanol, butanol, 2,3-butanediol, fatty acid ethyl esters, isoprenoids, organic acids, rare sugars, antioxidants, and sugar alcohols from glucose, xylose, cellobiose, galactose, acetate, alginate, mannitol, arabinose, and lactose.

  2. Nanofiltration concentration of extracellular glutathione produced by engineered Saccharomyces cerevisiae.

    Science.gov (United States)

    Sasaki, Kengo; Hara, Kiyotaka Y; Kawaguchi, Hideo; Sazuka, Takashi; Ogino, Chiaki; Kondo, Akihiko

    2016-01-01

    This study aimed to optimize extracellular glutathione production by a Saccharomyces cerevisiae engineered strain and to concentrate the extracellular glutathione by membrane separation processes, including ultrafiltration (UF) and nanofiltration (NF). Synthetic defined (SD) medium containing 20 g L(-1) glucose was fermented for 48 h; the fermentation liquid was passed through an UF membrane to remove macromolecules. Glutathione in this permeate was concentrated for 48 h to 545.1 ± 33.6 mg L(-1) using the NF membrane; this was a significantly higher concentration than that obtained with yeast extract peptone dextrose (YPD) medium following 96 h NF concentration (217.9 ± 57.4 mg L(-1)). This higher glutathione concentration results from lower cellular growth in SD medium (final OD600 = 6.9 ± 0.1) than in YPD medium (final OD600 = 11.0 ± 0.6) and thus higher production of extracellular glutathione (16.0 ± 1.3 compared to 9.2 ± 2.1 mg L(-1) in YPD medium, respectively). Similar fermentation and membrane processing of sweet sorghum juice containing 20 g L(-1) total sugars provided 240.3 ± 60.6 mg L(-1) glutathione. Increased extracellular production of glutathione by this engineered strain in SD medium and subsequent UF permeation and NF concentration in shortend time may help realize industrial recovery of extracellular glutathione.

  3. Cell wall dynamics modulate acetic acid-induced apoptotic cell death of Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    António Rego

    2014-08-01

    Full Text Available Acetic acid triggers apoptotic cell death in Saccharomyces cerevisiae, similar to mammalian apoptosis. To uncover novel regulators of this process, we analyzed whether impairing MAPK signaling affected acetic acid-induced apoptosis and found the mating-pheromone response and, especially, the cell wall integrity pathways were the major mediators, especially the latter, which we characterized further. Screening downstream effectors of this pathway, namely targets of the transcription factor Rlm1p, highlighted decreased cell wall remodeling as particularly important for acetic acid resistance. Modulation of cell surface dynamics therefore emerges as a powerful strategy to increase acetic acid resistance, with potential application in industrial fermentations using yeast, and in biomedicine to exploit the higher sensitivity of colorectal carcinoma cells to apoptosis induced by acetate produced by intestinal propionibacteria.

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

    Science.gov (United States)

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

    2015-10-01

    Production of lactic acid from renewable sugars has received growing attention as lactic acid can be used for making renewable and bio-based plastics. However, most prior studies have focused on production of lactic acid from glucose despite that cellulosic hydrolysates contain xylose as well as glucose. Microbial strains capable of fermenting both glucose and xylose into lactic acid are needed for sustainable and economic lactic acid production. In this study, we introduced a lactic acid-producing pathway into an engineered Saccharomyces cerevisiae capable of fermenting xylose. Specifically, ldhA from the fungi Rhizopus oryzae was overexpressed under the control of the PGK1 promoter through integration of the expression cassette in the chromosome. The resulting strain exhibited a high lactate dehydrogenase activity and produced lactic acid from glucose or xylose. Interestingly, we observed that the engineered strain exhibited substrate-dependent product formation. When the engineered yeast was cultured on glucose, the major fermentation product was ethanol while lactic acid was a minor product. In contrast, the engineered yeast produced lactic acid almost exclusively when cultured on xylose under oxygen-limited conditions. The yields of ethanol and lactic acid from glucose were 0.31 g ethanol/g glucose and 0.22 g lactic acid/g glucose, respectively. On xylose, the yields of ethanol and lactic acid were <0.01 g ethanol/g xylose and 0.69 g lactic acid/g xylose, respectively. These results demonstrate that lactic acid can be produced from xylose with a high yield by S. cerevisiae without deleting pyruvate decarboxylase, and the formation patterns of fermentations can be altered by substrates.

  5. Engineering Saccharomyces cerevisiae fatty acid composition for increased tolerance to octanoic acid.

    Science.gov (United States)

    Besada-Lombana, Pamela B; Fernandez-Moya, Ruben; Fenster, Jacob; Da Silva, Nancy A

    2017-03-14

    Biorenewable chemicals such as short and medium chain fatty acids enable functional or direct substitution of petroleum-derived building blocks, allowing reduction of anthropogenic greenhouse gases while meeting market needs of high-demand products like aliphatic alcohols and alpha olefins. However, producing these fatty acids in microorganisms can be challenging due to toxicity issues. Octanoic acid (C8) can disrupt the integrity of the cell membrane in yeast, and exogenous supplementation of oleic acid has been shown to help alleviate this. We recently engineered the Saccharomyces cerevisiae enzyme acetyl-CoA carboxylase by replacing serine residue 1157 with alanine to prevent deactivation by phosphorylation. Expression of Acc1(S1157A) in S. cerevisiae resulted in an increase in total fatty acid production, with the largest increase for oleic acid. In this study, we evaluated the effect of this modified lipid profile on C8 toxicity to the yeast. Expression of Acc1(S1157A) in S. cerevisiae BY4741 increased the percentage of oleic acid 3.1-fold and 1.6-fold in the absence and presence of octanoic acid challenge, respectively. Following exposure to 0.9 mM of C8 for 24 h, the engineered yeast had a 10-fold higher cell density relative to the baseline strain. Moreover, overexpressing Acc1(S1157A) allowed survival at C8 concentrations that were lethal for the baseline strain. This marked reduction of toxicity was shown to be due to higher membrane integrity as an 11-fold decrease in leakage of intracellular magnesium was observed. Due to the increase in oleic acid, this approach has the potential to reduce toxicity of other valuable bioproducts such as shorter chain aliphatic acids and alcohols and other membrane stressors. In an initial screen, increased resistance to n-butanol, 2-propanol and hexanoic acid was demonstrated with cell densities 3.2-fold, 1.8-fold, and 29-fold higher than the baseline strain, respectively. This article is protected by copyright. All

  6. Pathway Compartmentalization in Peroxisome of Saccharomyces cerevisiae to Produce Versatile Medium Chain Fatty Alcohols.

    Science.gov (United States)

    Sheng, Jiayuan; Stevens, Joseph; Feng, Xueyang

    2016-05-27

    Fatty alcohols are value-added chemicals and important components of a variety of industries, which have a >3 billion-dollar global market annually. Long chain fatty alcohols (>C12) are mainly used in surfactants, lubricants, detergents, pharmaceuticals and cosmetics while medium chain fatty alcohols (C6-C12) could be used as diesel-like biofuels. Microbial production of fatty alcohols from renewable feedstock stands as a promising strategy to enable sustainable supply of fatty alcohols. In this study, we report, for the first time, that medium chain fatty alcohols could be produced in yeast via targeted expression of a fatty acyl-CoA reductase (TaFAR) in the peroxisome of Saccharomyces cerevisiae. By tagging TaFAR enzyme with peroxisomal targeting signal peptides, the TaFAR could be compartmentalized into the matrix of the peroxisome to hijack the medium chain fatty acyl-CoA generated from the beta-oxidation pathway and convert them to versatile medium chain fatty alcohols (C10 &C12). The overexpression of genes encoding PEX7 and acetyl-CoA carboxylase further improved fatty alcohol production by 1.4-fold. After medium optimization in fed-batch fermentation using glucose as the sole carbon source, fatty alcohols were produced at 1.3 g/L, including 6.9% 1-decanol, 27.5% 1-dodecanol, 2.9% 1-tetradecanol and 62.7% 1-hexadecanol. This work revealed that peroxisome could be engineered as a compartmentalized organelle for producing fatty acid-derived chemicals in S. cerevisiae.

  7. Lactic acid production from cellobiose and xylose by engineered Saccharomyces cerevisiae.

    Science.gov (United States)

    Turner, Timothy L; Zhang, Guo-Chang; Oh, Eun Joong; Subramaniam, Vijay; Adiputra, Andrew; Subramaniam, Vimal; Skory, Christopher D; Jang, Ji Yeon; Yu, Byung Jo; Park, In; Jin, Yong-Su

    2016-05-01

    Efficient and rapid production of value-added chemicals from lignocellulosic biomass is an important step toward a sustainable society. Lactic acid, used for synthesizing the bioplastic polylactide, has been produced by microbial fermentation using primarily glucose. Lignocellulosic hydrolysates contain high concentrations of cellobiose and xylose. Here, we constructed a recombinant Saccharomyces cerevisiae strain capable of fermenting cellobiose and xylose into lactic acid. Specifically, genes (cdt-1, gh1-1, XYL1, XYL2, XYL3, and ldhA) coding for cellobiose transporter, β-glucosidase, xylose reductase, xylitol dehydrogenase, xylulokinase, and lactate dehydrogenase were integrated into the S. cerevisiae chromosomes. The resulting strain produced lactic acid from cellobiose or xylose with high yields. When fermenting a cellulosic sugar mixture containing 10 g/L glucose, 40 g/L xylose, and 80 g/L cellobiose, the engineered strain produced 83 g/L of lactic acid with a yield of 0.66 g lactic acid/g sugar (66% theoretical maximum). This study demonstrates initial steps toward the feasibility of sustainable production of lactic acid from lignocellulosic sugars by engineered yeast.

  8. [Advances in functional genomics studies underlying acetic acid tolerance of Saccharomyces cerevisiae].

    Science.gov (United States)

    Zhao, Xinqing; Zhang, Mingming; Xu, Guihong; Xu, Jianren; Bai, Fengwu

    2014-03-01

    Industrial microorganisms are subject to various stress conditions, including products and substrates inhibitions. Therefore, improvement of stress tolerance is of great importance for industrial microbial production. Acetic acid is one of the major inhibitors in the cellulosic hydrolysates, which affects seriously on cell growth and metabolism of Saccharomyces cerevisiae. Studies on the molecular mechanisms underlying adaptive response and tolerance of acetic acid of S. cerevisiae benefit breeding of robust strains of industrial yeast for more efficient production. In recent years, more insights into the molecular mechanisms underlying acetic acid tolerance have been revealed through analysis of global gene expression and metabolomics analysis, as well as phenomics analysis by single gene deletion libraries. Novel genes related to response to acetic acid and improvement of acetic acid tolerance have been identified, and novel strains with improved acetic acid tolerance were constructed by modifying key genes. Metal ions including potassium and zinc play important roles in acetic acid tolerance in S. cerevisiae, and the effect of zinc was first discovered in our previous studies on flocculating yeast. Genes involved in cell wall remodeling, membrane transport, energy metabolism, amino acid biosynthesis and transport, as well as global transcription regulation were discussed. Exploration and modification of the molecular mechanisms of yeast acetic acid tolerance will be done further on levels such as post-translational modifications and synthetic biology and engineering; and the knowledge obtained will pave the way for breeding robust strains for more efficient bioconversion of cellulosic materials to produce biofuels and bio-based chemicals.

  9. Metabolic engineering of Saccharomyces cerevisiae for production of fatty acid-derived biofuels and chemicals.

    Science.gov (United States)

    Runguphan, Weerawat; Keasling, Jay D

    2014-01-01

    As the serious effects of global climate change become apparent and access to fossil fuels becomes more limited, metabolic engineers and synthetic biologists are looking towards greener sources for transportation fuels. In recent years, microbial production of high-energy fuels by economically efficient bioprocesses has emerged as an attractive alternative to the traditional production of transportation fuels. Here, we engineered the budding yeast Saccharomyces cerevisiae to produce fatty acid-derived biofuels and chemicals from simple sugars. Specifically, we overexpressed all three fatty acid biosynthesis genes, namely acetyl-CoA carboxylase (ACC1), fatty acid synthase 1 (FAS1) and fatty acid synthase 2 (FAS2), in S. cerevisiae. When coupled to triacylglycerol (TAG) production, the engineered strain accumulated lipid to more than 17% of its dry cell weight, a four-fold improvement over the control strain. Understanding that TAG cannot be used directly as fuels, we also engineered S. cerevisiae to produce drop-in fuels and chemicals. Altering the terminal "converting enzyme" in the engineered strain led to the production of free fatty acids at a titer of approximately 400 mg/L, fatty alcohols at approximately 100mg/L and fatty acid ethyl esters (biodiesel) at approximately 5 mg/L directly from simple sugars. We envision that our approach will provide a scalable, controllable and economic route to this important class of chemicals.

  10. Engineering cellular redox balance in Saccharomyces cerevisiae for improved production of L-lactic acid.

    Science.gov (United States)

    Lee, Ju Young; Kang, Chang Duk; Lee, Seung Hyun; Park, Young Kyoung; Cho, Kwang Myung

    2015-04-01

    Owing to the growing market for the biodegradable and renewable polymer, polylactic acid, world demand for lactic acid is rapidly increasing. However, the very high concentrations desired for industrial production of the free lactic acid create toxicity and low pH concerns for manufacturers. Saccharomyces cerevisiae is the most well characterized eukaryote, a preferred microbial cell factory for the largest industrial biotechnology product (bioethanol), and a robust, commercially compatible workhorse to be exploited for the production of diverse chemicals. S. cerevisiae has also been explored as a host for lactic acid production because of its high acid tolerance. Here, we constructed an L-lactic acid-overproducing S. cerevisiae by redirecting cellular metabolic fluxes to the production of L-lactic acid. To this end, we deleted the S. cerevisiae genes encoding pyruvate decarboxylase 1 (PDC1), L-lactate cytochrome-c oxidoreductase (CYB2), and glycerol-3-phosphate dehydrogenase (GPD1), replacing them with a heterologous L-lactate dehydrogenase (LDH) gene. Two new target genes encoding isoenzymes of the external NADH dehydrogenase (NDE1 and NDE2), were also deleted from the genome to re-engineer the intracellular redox balance. The resulting strain was found to produce L-lactic acid more efficiently (32.6% increase in final L-lactic acid titer). When tested in a bioreactor in fed-batch mode, this engineered strain produced 117 g/L of L-lactic acid under low pH conditions. This result demonstrates that the redox balance engineering should be coupled with the metabolic engineering in the construction of L-lactic acid-overproducing S. cerevisiae.

  11. Metabolic engineering of Saccharomyces cerevisiae for production of carboxylic acids: current status and challenges.

    Science.gov (United States)

    Abbott, Derek A; Zelle, Rintze M; Pronk, Jack T; van Maris, Antonius J A

    2009-12-01

    To meet the demands of future generations for chemicals and energy and to reduce the environmental footprint of the chemical industry, alternatives for petrochemistry are required. Microbial conversion of renewable feedstocks has a huge potential for cleaner, sustainable industrial production of fuels and chemicals. Microbial production of organic acids is a promising approach for production of chemical building blocks that can replace their petrochemically derived equivalents. Although Saccharomyces cerevisiae does not naturally produce organic acids in large quantities, its robustness, pH tolerance, simple nutrient requirements and long history as an industrial workhorse make it an excellent candidate biocatalyst for such processes. Genetic engineering, along with evolution and selection, has been successfully used to divert carbon from ethanol, the natural endproduct of S. cerevisiae, to pyruvate. Further engineering, which included expression of heterologous enzymes and transporters, yielded strains capable of producing lactate and malate from pyruvate. Besides these metabolic engineering strategies, this review discusses the impact of transport and energetics as well as the tolerance towards these organic acids. In addition to recent progress in engineering S. cerevisiae for organic acid production, the key limitations and challenges are discussed in the context of sustainable industrial production of organic acids from renewable feedstocks.

  12. Effect of manganese ions on ethanol fermentation by xylose isomerase expressing Saccharomyces cerevisiae under acetic acid stress.

    Science.gov (United States)

    Ko, Ja Kyong; Um, Youngsoon; Lee, Sun-Mi

    2016-12-01

    The efficient fermentation of lignocellulosic hydrolysates in the presence of inhibitors is highly desirable for bioethanol production. Among the inhibitors, acetic acid released during the pretreatment of lignocellulose negatively affects the fermentation performance of biofuel producing organisms. In this study, we evaluated the inhibitory effects of acetic acid on glucose and xylose fermentation by a high performance engineered strain of xylose utilizing Saccharomyces cerevisiae, SXA-R2P-E, harboring a xylose isomerase based pathway. The presence of acetic acid severely decreased the xylose fermentation performance of this strain. However, the acetic acid stress was alleviated by metal ion supplementation resulting in a 52% increased ethanol production rate under 2g/L of acetic acid stress. This study shows the inhibitory effect of acetic acid on an engineered isomerase-based xylose utilizing strain and suggests a simple but effective method to improve the co-fermentation performance under acetic acid stress for efficient bioethanol production.

  13. Metabolic engineering and adaptive evolution for efficient production of D-lactic acid in Saccharomyces cerevisiae.

    Science.gov (United States)

    Baek, Seung-Ho; Kwon, Eunice Y; Kim, Yong Hwan; Hahn, Ji-Sook

    2016-03-01

    There is an increasing demand for microbial production of lactic acid (LA) as a monomer of biodegradable poly lactic acid (PLA). Both optical isomers, D-LA and L-LA, are required to produce stereocomplex PLA with improved properties. In this study, we developed Saccharomyces cerevisiae strains for efficient production of D-LA. D-LA production was achieved by expressing highly stereospecific D-lactate dehydrogenase gene (ldhA, LEUM_1756) from Leuconostoc mesenteroides subsp. mesenteroides ATCC 8293 in S. cerevisiae lacking natural LA production activity. D-LA consumption after glucose depletion was inhibited by deleting DLD1 encoding D-lactate dehydrogenase and JEN1 encoding monocarboxylate transporter. In addition, ethanol production was reduced by deleting PDC1 and ADH1 genes encoding major pyruvate decarboxylase and alcohol dehydrogenase, respectively, and glycerol production was eliminated by deleting GPD1 and GPD2 genes encoding glycerol-3-phosphate dehydrogenase. LA tolerance of the engineered D-LA-producing strain was enhanced by adaptive evolution and overexpression of HAA1 encoding a transcriptional activator involved in weak acid stress response, resulting in effective D-LA production up to 48.9 g/L without neutralization. In a flask fed-batch fermentation under neutralizing condition, our evolved strain produced 112.0 g/L D-LA with a yield of 0.80 g/g glucose and a productivity of 2.2 g/(L · h).

  14. Fermentation of xylose to produce ethanol by recombinant Saccharomyces cerevisiae strain containing XYLA and XKS1

    Institute of Scientific and Technical Information of China (English)

    LIU Xiaolin; JIANG Ning; HE Peng; LU Dajun; SHEN An

    2005-01-01

    Fermentation of the pentose sugar xylose to produce ethanol using lignocellulosic biomass would make bioethanol production economically more competitive. Saccharomyce cerevisise, an efficient ethanol producer, cannot utilize xylose because it lacks the ability to convert xylose to its isomer xylulose. In this study, XYLA gene encoding xylose isomerase (XI) from Thermoanaerobacter tengcongensis MB4T and XKS1 gene encoding xylulokinase (XK) from Pichia stipitis were cloned and functionally coexpressed in Saccharomyces cerevisiae EF-326 to construct a recombinant xylose-utilizing strain. The resulting strain S. cerevisiae EF 1014 not only grew on xylose as sole carbon source, but also produced ethanol under anaerobic conditions. Fermentations performed with different xylose concentrations at different temperatures demonstrated that the highest ethanol productivity was 0.11 g/g xylose when xylose concentration was provided at 50 g/L. Under this condition, 28.4% of xylose was consumed and 1.54 g/L xylitol was formed. An increasing fermentation temperature from 30℃ to 37℃ did not improve ethanol yield.

  15. New and efficient method using Saccharomyces cerevisiae mutants for identification of siderophores produced by microorganisms.

    Science.gov (United States)

    Park, Yong-Sung; Kim, Ji-Hyun; Chang, Hyo-Ihl; Kim, Seung-Wook; Paik, Hyun-Dong; Kang, Chang-Won; Kim, Tae-Hyoung; Sung, Ha-Chin; Yun, Cheol-Won

    2007-09-01

    The separation and identification of siderophores produced by microorganisms is a time-consuming and an expensive procedure. We have developed a new and efficient method to identify siderophores using well-established Saccharomyces cerevisiae deletion mutants. The Deltafet3,arn strains fail to sustain growth, even when specific siderophores are supplied, and mutants are siderophore-specific: Deltafet3,arn2 for triacetylfusarinine C (TAFC), Deltafet3,arn1,sit1 for ferrichrome (FC), and Deltafet3,sit1 for ferrioxamine B (FOB). The culture broth of Fusarium graminearum was separated by HPLC, and each peak was subjected to a plate assay using S. cerevisiae mutants. We have found that each peak contained specific siderophores produced by F. graminearum, and these coincided with reference siderophores. This method is quite novel because nobody tried this method to identify the siderophores. Furthermore, this method will save time and cost in the identification of siderophores produced by microorganisms.

  16. Screening of Non- Saccharomyces cerevisiae Strains for Tolerance to Formic Acid in Bioethanol Fermentation.

    Science.gov (United States)

    Oshoma, Cyprian E; Greetham, Darren; Louis, Edward J; Smart, Katherine A; Phister, Trevor G; Powell, Chris; Du, Chenyu

    2015-01-01

    Formic acid is one of the major inhibitory compounds present in hydrolysates derived from lignocellulosic materials, the presence of which can significantly hamper the efficiency of converting available sugars into bioethanol. This study investigated the potential for screening formic acid tolerance in non-Saccharomyces cerevisiae yeast strains, which could be used for the development of advanced generation bioethanol processes. Spot plate and phenotypic microarray methods were used to screen the formic acid tolerance of 7 non-Saccharomyces cerevisiae yeasts. S. kudriavzeii IFO1802 and S. arboricolus 2.3319 displayed a higher formic acid tolerance when compared to other strains in the study. Strain S. arboricolus 2.3319 was selected for further investigation due to its genetic variability among the Saccharomyces species as related to Saccharomyces cerevisiae and availability of two sibling strains: S. arboricolus 2.3317 and 2.3318 in the lab. The tolerance of S. arboricolus strains (2.3317, 2.3318 and 2.3319) to formic acid was further investigated by lab-scale fermentation analysis, and compared with S. cerevisiae NCYC2592. S. arboricolus 2.3319 demonstrated improved formic acid tolerance and a similar bioethanol synthesis capacity to S. cerevisiae NCYC2592, while S. arboricolus 2.3317 and 2.3318 exhibited an overall inferior performance. Metabolite analysis indicated that S. arboricolus strain 2.3319 accumulated comparatively high concentrations of glycerol and glycogen, which may have contributed to its ability to tolerate high levels of formic acid.

  17. Producing human ceramide-NS by metabolic engineering using yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Murakami, Suguru; Shimamoto, Toshi; Nagano, Hideaki; Tsuruno, Masahiro; Okuhara, Hiroaki; Hatanaka, Haruyo; Tojo, Hiromasa; Kodama, Yukiko; Funato, Kouichi

    2015-01-01

    Ceramide is one of the most important intercellular components responsible for the barrier and moisture retention functions of the skin. Because of the risks involved with using products of animal origin and the low productivity of plants, the availability of ceramides is currently limited. In this study, we successfully developed a system that produces sphingosine-containing human ceramide-NS in the yeast Saccharomyces cerevisiae by eliminating the genes for yeast sphingolipid hydroxylases (encoded by SUR2 and SCS7) and introducing the gene for a human sphingolipid desaturase (encoded by DES1). The inactivation of the ceramidase gene YDC1, overexpression of the inositol phosphosphingolipid phospholipase C gene ISC1, and endoplasmic reticulum localization of the DES1 gene product resulted in enhanced production of ceramide-NS. The engineered yeast strains can serve as hosts not only for providing a sustainable source of ceramide-NS but also for developing further systems to produce sphingosine-containing sphingolipids.

  18. Overproduction and secretion of free fatty acids through disrupted neutral lipid recycle in Saccharomyces cerevisiae.

    Science.gov (United States)

    Leber, Christopher; Polson, Brian; Fernandez-Moya, Ruben; Da Silva, Nancy A

    2015-03-01

    The production of fuels and chemicals from biorenewable resources is important to alleviate the environmental concerns, costs, and foreign dependency associated with the use of petroleum feedstock. Fatty acids are attractive biomolecules due to the flexibility of their iterative biosynthetic pathway, high energy content, and suitability for conversion into other secondary chemicals. Free fatty acids (FFAs) that can be secreted from the cell are particularly appealing due to their lower harvest costs and straightforward conversion into a broad range of biofuel and biochemical products. Saccharomyces cerevisiae was engineered to overproduce extracellular FFAs by targeting three native intracellular processes. β-oxidation was disrupted by gene knockouts in FAA2, PXA1 and POX1, increasing intracellular fatty acids levels up to 55%. Disruptions in the acyl-CoA synthetase genes FAA1, FAA4 and FAT1 allowed the extracellular detection of free fatty acids up to 490mg/L. Combining these two disrupted pathways, a sextuple mutant (Δfaa1 Δfaa4 Δfat1 Δfaa2 Δpxa1 Δpox1) was able to produce 1.3g/L extracellular free fatty acids. Further diversion of carbon flux into neutral lipid droplet formation was investigated by the overexpression of DGA1 or ARE1 and by the co-overexpression of a compatible lipase, TGL1, TGL3 or TGL5. The sextuple mutant overexpressing the diacylglycerol acyltransferase, DGA1, and the triacylglycerol lipase, TGL3, yielded 2.2g/L extracellular free fatty acids. This novel combination of pathway interventions led to 4.2-fold higher extracellular free fatty acid levels than previously reported for S. cerevisiae.

  19. Overexpression of acetyl-CoA synthetase in Saccharomyces cerevisiae increases acetic acid tolerance

    OpenAIRE

    Ding, Jun; Holzwarth, Garrett; Penner, Michael H.; Patton-Vogt, Jana; Bakalinsky, Alan T.

    2015-01-01

    Acetic acid-mediated inhibition of the fermentation of lignocellulose-derived sugars impedes development of plant biomass as a source of renewable ethanol. In order to overcome this inhibition, the capacity of Saccharomyces cerevisiae to synthesize acetyl-CoA from acetic acid was increased by overexpressing ACS2 encoding acetyl-coenzyme A synthetase. Overexpression of ACS2 resulted in higher resistance to acetic acid as measured by an increased growth rate and shorter lag phase relative to a ...

  20. Low acid producing solid propellants

    Science.gov (United States)

    Bennett, Robert R.

    1995-01-01

    The potential environmental effects of the exhaust products of conventional rocket propellants have been assessed by various groups. Areas of concern have included stratospheric ozone, acid rain, toxicity, air quality and global warming. Some of the studies which have been performed on this subject have concluded that while the impacts of rocket use are extremely small, there are propellant development options which have the potential to reduce those impacts even further. This paper discusses the various solid propellant options which have been proposed as being more environmentally benign than current systems by reducing HCI emissions. These options include acid neutralized, acid scavenged, and nonchlorine propellants. An assessment of the acid reducing potential and the viability of each of these options is made, based on current information. Such an assessment is needed in order to judge whether the potential improvements justify the expenditures of developing the new propellant systems.

  1. Substrate Specificity of Thiamine Pyrophosphate-Dependent 2-Oxo-Acid Decarboxylases in Saccharomyces cerevisiae

    NARCIS (Netherlands)

    Romagnoli, G.; Luttik, M.A.H.; Kötter, P.; Pronk, J.T.; Daran, J.M.

    2012-01-01

    Fusel alcohols are precursors and contributors to flavor and aroma compounds in fermented beverages, and some are under investigation as biofuels. The decarboxylation of 2-oxo acids is a key step in the Ehrlich pathway for fusel alcohol production. In Saccharomyces cerevisiae, five genes share seque

  2. Overexpression of acetyl-CoA synthetase in Saccharomyces cerevisiae increases acetic acid tolerance.

    Science.gov (United States)

    Ding, Jun; Holzwarth, Garrett; Penner, Michael H; Patton-Vogt, Jana; Bakalinsky, Alan T

    2015-01-01

    Acetic acid-mediated inhibition of the fermentation of lignocellulose-derived sugars impedes development of plant biomass as a source of renewable ethanol. In order to overcome this inhibition, the capacity of Saccharomyces cerevisiae to synthesize acetyl-CoA from acetic acid was increased by overexpressing ACS2 encoding acetyl-coenzyme A synthetase. Overexpression of ACS2 resulted in higher resistance to acetic acid as measured by an increased growth rate and shorter lag phase relative to a wild-type control strain, suggesting that Acs2-mediated consumption of acetic acid during fermentation contributes to acetic acid detoxification.

  3. Evaluation of emulsifier stability of biosurfactant produced by Saccharomyces lipolytica CCT-0913

    Directory of Open Access Journals (Sweden)

    Álvaro Silva Lima

    2009-04-01

    Full Text Available Surface-active compounds of biological origin are widely used for many industries (cosmetic, food, petrochemical. The Saccharomyces lipolytica CCT-0913 was able to grow and produce a biosurfactant on 5% (v/v diesel-oil at pH 5.0 and 32ºC. The cell-free broth emulsified and stabilized the oil-in-water emulsion through a first order kinetics. The results showed that the initial pH value and temperature influenced the emulsifier stability (ES, which was the time when oil was separated. The biosurfactant presented different stabilization properties for vegetable and mineral oil in water solution, despite the highest values of the ES occurring with vegetable oil. The biosurfactant presented smallest ES when compared to commercial surfactants; however, this biosurfactant was not purified.Os tensoativos de origem biológica são amplamente utilizados em diversas aplicações. O microrganismo Saccharomyces lipolytica CCT-0913 possui a habilidade de crescer em 5% (v/v óleo diesel a pH 5,0 e 32ºC e produzir biosurfactante. O caldo fermentado livre de células e produzido por S. lipolytica emulsiona e estabiliza emulsões óleo em água de acordo com uma cinética de primeira ordem. Os resultados mostram que o valor do pH inicial e a temperatura influenciam a estabilidade emulsificante (ES, que é medido pelo tempo que a quantidade de óleo. O biosurfactante apresenta diferentes valores de estabilidade emulsificante para óleos vegetais e minerais em emulsões óleo-água, os maiores valores de ES ocorrem nas emulsões utilizando óleo vegetal. O biosurfactante apresenta valores baixos de ES quando comparado com emulsificantes comerciais, entretanto sem sofrer nenhum processo de purificação.

  4. Ethanol production from D-lactic acid by lactic acid-assimilating Saccharomyces cerevisiae NAM34-4C.

    Science.gov (United States)

    Wakamatsu, Makoto; Tani, Tatsunori; Taguchi, Hisataka; Matsuoka, Masayoshi; Kida, Kenji; Akamatsu, Takashi

    2013-07-01

    The lactic acid-assimilating yeast Saccharomyces cerevisiae NAM34-4C grew rapidly in minimal D-lactate medium (pH 3.5) at 35°C, compared with minimal L-lactate medium. A laboratory strain, S. cerevisiae S288C, did not grow in either medium at pH 3.5. Strain NAM34-4C produced remarkably high levels of ethanol in YPDL medium at pH 3.5, but not at pH 5.5, when D-lactate was provided as the carbon source. Optimal cultivation conditions for ethanol production from D-lactate by strain NAM34-4C were as follows: shaking speed, 60 rpm; initial pH, 3.0; cultivation temperature, 35°C; yeast extract, 5 g/L; peptone, 10 g/L; and D-lactate, 30 g/L. Under these conditions, strain NAM34-4C produced 2.7 g/L ethanol, which is 18% of the theoretical maximal yield (0.51 3 initial D-lactate concentration).

  5. Kluyveromyces lactis and Saccharomyces cerevisiae, two potent deacidifying and volatile-sulphur-aroma-producing microorganisms of the cheese ecosystem.

    Science.gov (United States)

    Kagkli, Dafni-Maria; Tâche, Roselyne; Cogan, Timothy M; Hill, Colin; Casaregola, Serge; Bonnarme, Pascal

    2006-11-01

    Cheese flavour is the result of complex biochemical transformations attributed to bacteria and yeasts grown on the curd of smear-ripened cheeses. Volatile sulphur compounds (VSCs) are responsible for the characteristic aromatic notes of several cheeses. In the present study, we have assessed the ability of Kluyveromyces lactis, Kluyveromyces marxianus and Saccharomyces cerevisiae strains, which are frequently isolated from smear-ripened cheeses, to grow and deacidify a cheese medium and generate VSCs resulting from L-methionine degradation. The Kluyveromyces strains produced a wider variety and higher amounts of VSCs than the S. cerevisiae ones. We have shown that the pathway is likely to be proceeding differently in these two yeast genera. The VSCs are mainly generated through the degradation of 4-methylthio-oxobutyric acid in the Kluyveromyces strains, in contrast to the S. cerevisiae ones which have higher L-methionine demethiolating activity, resulting in a direct conversion of L-methionine to methanethiol. The deacidification activity which is of major importance in the early stages of cheese-ripening was also compared in S. cerevisiae and Kluyveromyces strains.

  6. Interaction of Lactobacillus vini with the ethanol-producing yeasts Dekkera bruxellensis and Saccharomyces cerevisiae.

    Science.gov (United States)

    Tiukova, Ievgeniia; Eberhard, Thomas; Passoth, Volkmar

    2014-01-01

    Lactobacillus vini was recently described as a contaminant in industrial ethanol fermentations and its co-occurrence with Dekkera bruxellensis was noted. We investigated the growth characteristics of L. vini in cocultivation together with either Saccharomyces cerevisiae or D. bruxellensis. Lower cell numbers of both the yeasts and L. vini as well as a decrease in ethanol and lactate formation in mixed batch cultures compared with pure cultures were noted. L. vini formed cell aggregates (flocs) in all cultivation media with different shapes in Man-Rogosa-Sharpe and yeast extract-peptone-dextrose media. Flocs' size and proportion of cells bound to flocs increased with increasing ethanol concentration. In coculture, formation of lactic acid bacteria-yeast cell aggregates consisting of a bacterial core with an outer layer of yeast cells was observed. L. vini-D. bruxellensis flocs had a bigger surface, due to cells protruding from the pseudomycelium. The involvement of mannose residues in the flocculation between L. vini and yeasts was tested. The presence of mannose induced deflocculation in a concentration-dependent manner. Less mannose was required for the deflocculation of D. bruxellensis as compared with S. cerevisiae.

  7. Malic acid production by Saccharomyces cerevisiae: engineering of pyruvate carboxylation, oxaloacetate reduction, and malate export.

    Science.gov (United States)

    Zelle, Rintze M; de Hulster, Erik; van Winden, Wouter A; de Waard, Pieter; Dijkema, Cor; Winkler, Aaron A; Geertman, Jan-Maarten A; van Dijken, Johannes P; Pronk, Jack T; van Maris, Antonius J A

    2008-05-01

    Malic acid is a potential biomass-derivable "building block" for chemical synthesis. Since wild-type Saccharomyces cerevisiae strains produce only low levels of malate, metabolic engineering is required to achieve efficient malate production with this yeast. A promising pathway for malate production from glucose proceeds via carboxylation of pyruvate, followed by reduction of oxaloacetate to malate. This redox- and ATP-neutral, CO(2)-fixing pathway has a theoretical maximum yield of 2 mol malate (mol glucose)(-1). A previously engineered glucose-tolerant, C(2)-independent pyruvate decarboxylase-negative S. cerevisiae strain was used as the platform to evaluate the impact of individual and combined introduction of three genetic modifications: (i) overexpression of the native pyruvate carboxylase encoded by PYC2, (ii) high-level expression of an allele of the MDH3 gene, of which the encoded malate dehydrogenase was retargeted to the cytosol by deletion of the C-terminal peroxisomal targeting sequence, and (iii) functional expression of the Schizosaccharomyces pombe malate transporter gene SpMAE1. While single or double modifications improved malate production, the highest malate yields and titers were obtained with the simultaneous introduction of all three modifications. In glucose-grown batch cultures, the resulting engineered strain produced malate at titers of up to 59 g liter(-1) at a malate yield of 0.42 mol (mol glucose)(-1). Metabolic flux analysis showed that metabolite labeling patterns observed upon nuclear magnetic resonance analyses of cultures grown on (13)C-labeled glucose were consistent with the envisaged nonoxidative, fermentative pathway for malate production. The engineered strains still produced substantial amounts of pyruvate, indicating that the pathway efficiency can be further improved.

  8. [Construction of high sulphite-producing industrial strain of Saccharomyces cerevisiae].

    Science.gov (United States)

    Qu, Na; He, Xiu-ping; Guo, Xue-na; Liu, Nan; Zhang, Bo-run

    2006-02-01

    In the process of beer storage and transportation, off-flavor can be produced for oxidation of beer. Sulphite is important for stabilizing the beer flavor because of its antioxidant activity. However, the low level of sulphite synthesized by the brewing yeast is not enough to stabilize beer flavor. Three enzymes involve sulphite biosynthesis in yeast. One of them, APS kinase (encoded by MET14) plays important role in the process of sulphite formation. In order to construct high sulphite-producing brewing yeast strain for beer production, MET14 gene was cloned and overexpressed in industrial strain of Saccharomyces cerevisiae. Primer 1 (5'-TGTGAATTCCTGTACACCAATGGCTACT-3', EcoR I) and primer 2 (5'-TATAAGCTTGATGA GGTGGATGAAGACG-3', HindIII) were designed according to the MET14 sequence in GenBank. A 1.1kb DNA fragment containing the open reading frame and terminator of MET14 gene was amplified from Saccharomyces cerevisiae YSF-5 by PCR, and inserted into YEp352 to generate recombinant plasmid pMET14. To express MET14 gene properly in S. cerevisiae, the recombinant expression plasmids pPM with URA3 gene as the selection marker and pCPM with URA3 gene and copper resistance gene as the selection marker for yeast transformation were constructed. In plasmid pPM, the PGK1 promoter from plasmid pVC727 was fused with the MET14 gene from pMET14, and the expression cassette was inserted into the plasmid YEp352. The dominant selection marker, copper-resistance gene expression cassette CUP1-MTI was inserted in plasmid pPM to result in pCPM. Restriction enzyme analysis showed that plasmids pPM and pCPM were constructed correctly. The laboratory strain of S. cerevisiae YS58 with ura3, trp1, leu2, his4 auxotroph was transformed with plasmid pPM. Yeast transformants were screened on synthetic minimal medium (SD) containing leucine, histidine and tryptophan. The sulphite production of the transformants carrying pPM was 2 fold of that in the control strain YS58, which showed that the

  9. High temperature stimulates acetic acid accumulation and enhances the growth inhibition and ethanol production by Saccharomyces cerevisiae under fermenting conditions.

    Science.gov (United States)

    Woo, Ji-Min; Yang, Kyung-Mi; Kim, Sae-Um; Blank, Lars M; Park, Jin-Byung

    2014-07-01

    Cellular responses of Saccharomyces cerevisiae to high temperatures of up to 42 °C during ethanol fermentation at a high glucose concentration (i.e., 100 g/L) were investigated. Increased temperature correlated with stimulated glucose uptake to produce not only the thermal protectant glycerol but also ethanol and acetic acid. Carbon flux into the tricarboxylic acid (TCA) cycle correlated positively with cultivation temperature. These results indicate that the increased demand for energy (in the form of ATP), most likely caused by multiple stressors, including heat, acetic acid, and ethanol, was matched by both the fermentation and respiration pathways. Notably, acetic acid production was substantially stimulated compared to that of other metabolites during growth at increased temperature. The acetic acid produced in addition to ethanol seemed to subsequently result in adverse effects, leading to increased production of reactive oxygen species. This, in turn, appeared to cause the specific growth rate, and glucose uptake rate reduced leading to a decrease of the specific ethanol production rate far before glucose depletion. These results suggest that adverse effects from heat, acetic acid, ethanol, and oxidative stressors are synergistic, resulting in a decrease of the specific growth rate and ethanol production rate and, hence, are major determinants of cell stability and ethanol fermentation performance of S. cerevisiae at high temperatures. The results are discussed in the context of possible applications.

  10. Exopolysaccharides produced by lactic acid bacteria

    NARCIS (Netherlands)

    Caggianiello, Graziano; Kleerebezem, Michiel; Spano, Giuseppe

    2016-01-01

    A wide range of lactic acid bacteria (LAB) is able to produce capsular or extracellular polysaccharides, with various chemical compositions and properties. Polysaccharides produced by LAB alter the rheological properties of the matrix in which they are dispersed, leading to typically viscous and

  11. Trehalose accumulation enhances tolerance of Saccharomyces cerevisiae to acetic acid.

    Science.gov (United States)

    Yoshiyama, Yoko; Tanaka, Koichi; Yoshiyama, Kohei; Hibi, Makoto; Ogawa, Jun; Shima, Jun

    2015-02-01

    Trehalose confers protection against various environmental stresses on yeast cells. In this study, trehalase gene deletion mutants that accumulate trehalose at high levels showed significant stress tolerance to acetic acid. The enhancement of trehalose accumulation can thus be considered a target in the breeding of acetic acid-tolerant yeast strains.

  12. Development of Bottom-Fermenting Saccharomyces Strains That Produce High SO2 Levels, Using Integrated Metabolome and Transcriptome Analysis▿

    OpenAIRE

    Yoshida, Satoshi; Imoto, Jun; Minato, Toshiko; Oouchi, Rie; Sugihara, Mao; IMAI, Takeo; Ishiguro, Tatsuji; Mizutani, Satoru; Tomita,Masaru; Soga, Tomoyoshi; Yoshimoto, Hiroyuki

    2008-01-01

    Sulfite plays an important role in beer flavor stability. Although breeding of bottom-fermenting Saccharomyces strains that produce high levels of SO2 is desirable, it is complicated by the fact that undesirable H2S is produced as an intermediate in the same pathway. Here, we report the development of a high-level SO2-producing bottom-fermenting yeast strain by integrated metabolome and transcriptome analysis. This analysis revealed that O-acetylhomoserine (OAH) is the rate-limiting factor fo...

  13. Industrial systems biology of Saccharomyces cerevisiae enables novel succinic acid cell factory.

    Directory of Open Access Journals (Sweden)

    José Manuel Otero

    Full Text Available Saccharomyces cerevisiae is the most well characterized eukaryote, the preferred microbial cell factory for the largest industrial biotechnology product (bioethanol, and a robust commerically compatible scaffold to be exploitted for diverse chemical production. Succinic acid is a highly sought after added-value chemical for which there is no native pre-disposition for production and accmulation in S. cerevisiae. The genome-scale metabolic network reconstruction of S. cerevisiae enabled in silico gene deletion predictions using an evolutionary programming method to couple biomass and succinate production. Glycine and serine, both essential amino acids required for biomass formation, are formed from both glycolytic and TCA cycle intermediates. Succinate formation results from the isocitrate lyase catalyzed conversion of isocitrate, and from the α-keto-glutarate dehydrogenase catalyzed conversion of α-keto-glutarate. Succinate is subsequently depleted by the succinate dehydrogenase complex. The metabolic engineering strategy identified included deletion of the primary succinate consuming reaction, Sdh3p, and interruption of glycolysis derived serine by deletion of 3-phosphoglycerate dehydrogenase, Ser3p/Ser33p. Pursuing these targets, a multi-gene deletion strain was constructed, and directed evolution with selection used to identify a succinate producing mutant. Physiological characterization coupled with integrated data analysis of transcriptome data in the metabolically engineered strain were used to identify 2(nd-round metabolic engineering targets. The resulting strain represents a 30-fold improvement in succinate titer, and a 43-fold improvement in succinate yield on biomass, with only a 2.8-fold decrease in the specific growth rate compared to the reference strain. Intuitive genetic targets for either over-expression or interruption of succinate producing or consuming pathways, respectively, do not lead to increased succinate. Rather, we

  14. New mechanisms that regulate Saccharomyces cerevisiae short peptide transporter achieve balanced intracellular amino acid concentrations.

    Science.gov (United States)

    Melnykov, Artem V

    2016-01-01

    The budding yeast Saccharomyces cerevisiae is able to take up large quantities of amino acids in the form of di- and tripeptides via a short peptide transporter, Ptr2p. It is known that PTR2 can be induced by certain peptides and amino acids, and the mechanisms governing this upregulation are understood at the molecular level. We describe two new opposing mechanisms of regulation that emphasize potential toxicity of amino acids: the first is upregulation of PTR2 in a population of cells, caused by amino acid secretion that accompanies peptide uptake; the second is loss of Ptr2p activity, due to transporter internalization following peptide uptake. Our findings emphasize the importance of proper amino acid balance in the cell and extend understanding of peptide import regulation in yeast.

  15. Weak-acid preservatives: pH and proton movements in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Stratford, Malcolm; Nebe-von-Caron, Gerhard; Steels, Hazel; Novodvorska, Michaela; Ueckert, Joerg; Archer, David B

    2013-02-15

    Weak-acid preservatives commonly used to prevent fungal spoilage of low pH foods include sorbic and acetic acids. The "classical weak-acid theory" proposes that weak acids inhibit spoilage organisms by diffusion of undissociated acids through the membrane, dissociation within the cell to protons and anions, and consequent acidification of the cytoplasm. Results from 25 strains of Saccharomyces cerevisiae confirmed inhibition by acetic acid at a molar concentration 42 times higher than sorbic acid, in contradiction of the weak-acid theory where all acids of equal pK(a) should inhibit at equimolar concentrations. Flow cytometry showed that the intracellular pH fell to pH 4.7 at the growth-inhibitory concentration of acetic acid, whereas at the inhibitory concentration of sorbic acid, the pH only fell to pH 6.3. The plasma membrane H⁺-ATPase proton pump (Pma1p) was strongly inhibited by sorbic acid at the growth-inhibitory concentration, but was stimulated by acetic acid. The H⁺-ATPase was also inhibited by lower sorbic acid concentrations, but later showed recovery and elevated activity if the sorbic acid was removed. Levels of PMA1 transcripts increased briefly following sorbic acid addition, but soon returned to normal levels. It was concluded that acetic acid inhibition of S. cerevisiae was due to intracellular acidification, in accord with the "classical weak-acid theory". Sorbic acid, however, appeared to be a membrane-active antimicrobial compound, with the plasma membrane H⁺-ATPase proton pump being a primary target of inhibition. Understanding the mechanism of action of sorbic acid will hopefully lead to improved methods of food preservation.

  16. Production of non-alcoholic beer using free and immobilized cells of Saccharomyces cerevisiae deficient in the tricarboxylic acid cycle.

    Science.gov (United States)

    Navrátil, Marián; Dömény, Zoltán; Sturdík, Ernest; Smogrovicová, Daniela; Gemeiner, Peter

    2002-04-01

    Production of non-alcoholic beer using Saccharomyces cerevisiae has been studied. Non-recombinant mutant strains with a defect in the synthesis of tricarboxylic-acid-cycle enzymes were used and applied in both free and pectate-immobilized form, using both batch and packed-bed continuous systems. After fermentation, basic parameters of the beer produced by five mutant strains were compared with a standard strain of brewing yeast. Results showed that the beer prepared by mutant yeast cells was characterized by lower levels of total alcohols, with ethanol concentrations between 0.07 and 0.31% (w/w). The organic acids produced, especially lactic acid, in concentrations up to 1.38 g x l(-1) had a strong protective effect on the microbial stability of the final product and thus the usual addition of lactic acid could be omitted. Application of the yeast mutants appears to be a good alternative to the classical methods for the production of non-alcoholic beer.

  17. Introduction of a bacterial acetyl-CoA synthesis pathway improves lactic acid production in Saccharomyces cerevisiae.

    Science.gov (United States)

    Song, Ji-Yoon; Park, Joon-Song; Kang, Chang Duk; Cho, Hwa-Young; Yang, Dongsik; Lee, Seunghyun; Cho, Kwang Myung

    2016-05-01

    Acid-tolerant Saccharomyces cerevisiae was engineered to produce lactic acid by expressing heterologous lactate dehydrogenase (LDH) genes, while attenuating several key pathway genes, including glycerol-3-phosphate dehydrogenase1 (GPD1) and cytochrome-c oxidoreductase2 (CYB2). In order to increase the yield of lactic acid further, the ethanol production pathway was attenuated by disrupting the pyruvate decarboxylase1 (PDC1) and alcohol dehydrogenase1 (ADH1) genes. Despite an increase in lactic acid yield, severe reduction of the growth rate and glucose consumption rate owing to the absence of ADH1 caused a considerable decrease in the overall productivity. In Δadh1 cells, the levels of acetyl-CoA, a key precursor for biologically applicable components, could be insufficient for normal cell growth. To increase the cellular supply of acetyl-CoA, we introduced bacterial acetylating acetaldehyde dehydrogenase (A-ALD) enzyme (EC 1.2.1.10) genes into the lactic acid-producing S. cerevisiae. Escherichia coli-derived A-ALD genes, mhpF and eutE, were expressed and effectively complemented the attenuated acetaldehyde dehydrogenase (ALD)/acetyl-CoA synthetase (ACS) pathway in the yeast. The engineered strain, possessing a heterologous acetyl-CoA synthetic pathway, showed an increased glucose consumption rate and higher productivity of lactic acid fermentation. The production of lactic acid was reached at 142g/L with production yield of 0.89g/g and productivity of 3.55gL(-1)h(-1) under fed-batch fermentation in bioreactor. This study demonstrates a novel approach that improves productivity of lactic acid by metabolic engineering of the acetyl-CoA biosynthetic pathway in yeast.

  18. Deletion of the Saccharomyces cerevisiae ARO8 gene, encoding an aromatic amino acid transaminase, enhances phenylethanol production from glucose.

    Science.gov (United States)

    Romagnoli, Gabriele; Knijnenburg, Theo A; Liti, Gianni; Louis, Edward J; Pronk, Jack T; Daran, Jean-Marc

    2015-01-01

    Phenylethanol has a characteristic rose-like aroma that makes it a popular ingredient in foods, beverages and cosmetics. Microbial production of phenylethanol currently relies on whole-cell bioconversion of phenylalanine with yeasts that harbour an Ehrlich pathway for phenylalanine catabolism. Complete biosynthesis of phenylethanol from a cheap carbon source, such as glucose, provides an economically attractive alternative for phenylalanine bioconversion. In this study, synthetic genetic array (SGA) screening was applied to identify genes involved in regulation of phenylethanol synthesis in Saccharomyces cerevisiae. The screen focused on transcriptional regulation of ARO10, which encodes the major decarboxylase involved in conversion of phenylpyruvate to phenylethanol. A deletion in ARO8, which encodes an aromatic amino acid transaminase, was found to underlie the transcriptional upregulation of ARO10 during growth, with ammonium sulphate as the sole nitrogen source. Physiological characterization revealed that the aro8Δ mutation led to substantial changes in the absolute and relative intracellular concentrations of amino acids. Moreover, deletion of ARO8 led to de novo production of phenylethanol during growth on a glucose synthetic medium with ammonium as the sole nitrogen source. The aro8Δ mutation also stimulated phenylethanol production when combined with other, previously documented, mutations that deregulate aromatic amino acid biosynthesis in S. cerevisiae. The resulting engineered S. cerevisiae strain produced >3 mm phenylethanol from glucose during growth on a simple synthetic medium. The strong impact of a transaminase deletion on intracellular amino acid concentrations opens new possibilities for yeast-based production of amino acid-derived products.

  19. Recovery of carboxylic acids produced by fermentation.

    Science.gov (United States)

    López-Garzón, Camilo S; Straathof, Adrie J J

    2014-01-01

    Carboxylic acids such as citric, lactic, succinic and itaconic acids are useful products and are obtained on large scale by fermentation. This review describes the options for recovering these and other fermentative carboxylic acids. After cell removal, often a primary recovery step is performed, using liquid-liquid extraction, adsorption, precipitation or conventional electrodialysis. If the carboxylate is formed rather than the carboxylic acid, the recovery process involves a step for removing the cation of the formed carboxylate. Then, bipolar electrodialysis and thermal methods for salt splitting can prevent that waste inorganic salts are co-produced. Final carboxylic acid purification requires either distillation or crystallization, usually involving evaporation of water. Process steps can often be combined synergistically. In-situ removal of carboxylic acid by extraction during fermentation is the most popular approach. Recovery of the extractant can easily lead to waste inorganic salt formation, which counteracts the advantage of the in-situ removal. For industrial production, various recovery principles and configurations are used, because the fermentation conditions and physical properties of specific carboxylic acids differ.

  20. Genomic diversity of Saccharomyces cerevisiae yeasts associated with alcoholic fermentation of bacanora produced by artisanal methods.

    Science.gov (United States)

    Álvarez-Ainza, M L; Zamora-Quiñonez, K A; Moreno-Ibarra, G M; Acedo-Félix, E

    2015-03-01

    Bacanora is a spirituous beverage elaborated with Agave angustifolia Haw in an artisanal process. Natural fermentation is mostly performed with native yeasts and bacteria. In this study, 228 strains of yeast like Saccharomyces were isolated from the natural alcoholic fermentation on the production of bacanora. Restriction analysis of the amplified region ITS1-5.8S-ITS2 of the ribosomal DNA genes (RFLPr) were used to confirm the genus, and 182 strains were identified as Saccharomyces cerevisiae. These strains displayed high genomic variability in their chromosomes profiles by karyotyping. Electrophoretic profiles of the strains evaluated showed a large number of chromosomes the size of which ranged between 225 and 2200 kpb approximately.

  1. Aroma Compounds Prevision using Artificial Neural Networks Influence of Newly Indigenous Saccharomyces SPP in White Wine Produced with Vitis Vinifera Cv Siria

    OpenAIRE

    Caldeira,A. Teresa; Martins, M. Rosário; Cabrita,Maria João; Ambrósio, Cristina; Arteiro, José; José NEVES; Vicente, Henrique

    2010-01-01

    Commercial yeasts strains of Saccharomyces cerevisae are frequently used in white wine production as starters in fermentation process, however, these strains can affect the wine characteristics. The aim of this study was to evaluate the effect of three strains of Saccharomyces spp. (var. 1, 2 and 3) on wine aroma compounds produced in microvinification assays. Microvinification assays were carried out with Vitis vinifera cv Síria grapes using the strains in study as starters. Aroma compounds ...

  2. Production of tranilast [N-(3',4'-dimethoxycinnamoyl)-anthranilic acid] and its analogs in yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Eudes, Aymerick; Baidoo, Edward E K; Yang, Fan; Burd, Helcio; Hadi, Masood Z; Collins, F William; Keasling, Jay D; Loqué, Dominique

    2011-02-01

    Biological synthesis of therapeutic drugs beneficial for human health using microbes offers an alternative production strategy to the methods that are commonly employed such as direct extraction from source organisms or chemical synthesis. In this study, we evaluated the potential for yeast (Saccharomyces cerevisiae) to be used as a catalyst for the synthesis of tranilast and various tranilast analogs (cinnamoyl anthranilates). Several studies have demonstrated that these phenolic amides have antioxidant properties and potential therapeutic benefits including antiinflammatory, antiproliferative, and antigenotoxic effects. The few cinnamoyl anthranilates naturally produced in plants such as oats and carnations result from the coupling of various hydroxycinnamoyl-CoAs to anthranilic acid. In order to achieve the microbial production of tranilast and several of its analogs, we engineered a yeast strain to co-express a 4-coumarate/CoA ligase (4CL, EC 6.2.1.12) from Arabidopsis thaliana and a hydroxycinnamoyl/benzoyl-CoA/anthranilate N-hydroxycinnamoyl/benzoyltransferase (HCBT, EC 2.3.1.144) from Dianthus caryophyllus. This modified yeast strain allowed us to produce tranilast and 26 different cinnamoyl anthranilate molecules within a few hours after exogenous supply of various combinations of cinnamic acids and anthranilate derivatives. Our data demonstrate the feasibility of rapidly producing a wide range of defined cinnamoyl anthranilates in yeast and underline a potential for the biological designed synthesis of naturally and non-naturally occurring molecules.

  3. Molecular mechanisms of Saccharomyces cerevisiae stress adaptation and programmed cell death in response to acetic acid

    Directory of Open Access Journals (Sweden)

    Sergio eGiannattasio

    2013-02-01

    Full Text Available Beyond its classical biotechnological applications such as food and beverage production or as a cell factory, the yeast Saccharomyces cerevisiae is a valuable model organism to study fundamental mechanisms of cell response to stressful environmental changes. Acetic acid is a physiological product of yeast fermentation and it is a well-known food preservative due to its antimicrobial action. Acetic acid has recently been shown to cause yeast cell death and aging. Here we shall focus on the molecular mechanisms of S. cerevisiae stress adaptation and programmed cell death in response to acetic acid. We shall elaborate on the intracellular signaling pathways involved in the cross-talk of pro-survival and pro-death pathways underlying the importance of understanding fundamental aspects of yeast cell homeostasis to improve the performance of a given yeast strain in biotechnological applications.

  4. Zinc, magnesium, and calcium ion supplementation confers tolerance to acetic acid stress in industrial Saccharomyces cerevisiae utilizing xylose.

    Science.gov (United States)

    Ismail, Ku Syahidah Ku; Sakamoto, Takatoshi; Hasunuma, Tomohisa; Zhao, Xin-Qing; Kondo, Akihiko

    2014-12-01

    Lignocellulosic biomass is a potential substrate for ethanol production. However, pretreatment of lignocellulosic materials produces inhibitory compounds such as acetic acid, which negatively affect ethanol production by Saccharomyces cerevisiae. Supplementation of the medium with three metal ions (Zn(2+) , Mg(2+) , and Ca(2+) ) increased the tolerance of S. cerevisiae toward acetic acid compared to the absence of the ions. Ethanol production from xylose was most improved (by 34%) when the medium was supplemented with 2 mM Ca(2+) , followed by supplementation with 3.5 mM Mg(2+) (29% improvement), and 180 μM Zn(2+) (26% improvement). Higher ethanol production was linked to high cell viability in the presence of metal ions. Comparative transcriptomics between the supplemented cultures and the control suggested that improved cell viability resulted from the induction of genes controlling the cell wall and membrane. Only one gene, FIT2, was found to be up-regulated in common between the three metal ions. Also up-regulation of HXT1 and TKL1 might enhance xylose consumption in the presence of acetic acid. Thus, the addition of ionic nutrients is a simple and cost-effective method to improve the acetic acid tolerance of S. cerevisiae.

  5. Synthesis of FAEEs from glycerol in engineered Saccharomyces cerevisiae using endogenously produced ethanol by heterologous expression of an unspecific bacterial acyltransferase.

    Science.gov (United States)

    Yu, Kyung Ok; Jung, Ju; Kim, Seung Wook; Park, Chul Hwan; Han, Sung Ok

    2012-01-01

    The high price of petroleum-based diesel fuel has led to the development of alternative fuels, such as ethanol. Saccharomyces cerevisiae was metabolically engineered to utilize glycerol as a substrate for ethanol production. For the synthesis of fatty acid ethyl esters (FAEEs) by engineered S. cerevisiae that utilize glycerol as substrate, heterologous expression of an unspecific acyltransferase from Acinetobacter baylyi with glycerol utilizing genes was established. As a result, the engineered YPH499 (pGcyaDak, pGupWs-DgaTCas) strain produced 0.24 g/L FAEEs using endogenous ethanol produced from glycerol. And this study also demonstrated the possibility of increasing FAEE production by enhancing ethanol production by minimizing the synthesis of glycerol. The overall FAEE production in strain YPH499 fps1Δ gpd2Δ (pGcyaDak, pGupWs-DgaTCas) was 2.1-fold more than in YPH499 (pGcyaDak, pGupWs-DgaTCas), with approximately 0.52 g/L FAEEs produced, while nearly 17 g/L of glycerol was consumed. These results clearly indicated that FAEEs were synthesized in engineered S. cerevisiae by esterifying exogenous fatty acids with endogenously produced ethanol from glycerol. This microbial system acts as a platform in applying metabolic engineering that allows the production of FAEEs from cheap and abundant substrates specifically glycerol through the use of endogenous bioethanol.

  6. Transcription activator-like effector nucleases mediated metabolic engineering for enhanced fatty acids production in Saccharomyces cerevisiae

    KAUST Repository

    Aouida, Mustapha

    2015-04-01

    Targeted engineering of microbial genomes holds much promise for diverse biotechnological applications. Transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats/Cas9 systems are capable of efficiently editing microbial genomes, including that of Saccharomyces cerevisiae. Here, we demonstrate the use of TALENs to edit the genome of S.cerevisiae with the aim of inducing the overproduction of fatty acids. Heterodimeric TALENs were designed to simultaneously edit the FAA1 and FAA4 genes encoding acyl-CoA synthetases in S.cerevisiae. Functional yeast double knockouts generated using these TALENs over-produce large amounts of free fatty acids into the cell. This study demonstrates the use of TALENs for targeted engineering of yeast and demonstrates that this technology can be used to stimulate the enhanced production of free fatty acids, which are potential substrates for biofuel production. This proof-of-principle study extends the utility of TALENs as excellent genome editing tools and highlights their potential use for metabolic engineering of yeast and other organisms, such as microalgae and plants, for biofuel production. © 2015 The Society for Biotechnology, Japan.

  7. Transcription activator-like effector nucleases mediated metabolic engineering for enhanced fatty acids production in Saccharomyces cerevisiae.

    Science.gov (United States)

    Aouida, Mustapha; Li, Lixin; Mahjoub, Ali; Alshareef, Sahar; Ali, Zahir; Piatek, Agnieszka; Mahfouz, Magdy M

    2015-10-01

    Targeted engineering of microbial genomes holds much promise for diverse biotechnological applications. Transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats/Cas9 systems are capable of efficiently editing microbial genomes, including that of Saccharomyces cerevisiae. Here, we demonstrate the use of TALENs to edit the genome of S. cerevisiae with the aim of inducing the overproduction of fatty acids. Heterodimeric TALENs were designed to simultaneously edit the FAA1 and FAA4 genes encoding acyl-CoA synthetases in S. cerevisiae. Functional yeast double knockouts generated using these TALENs over-produce large amounts of free fatty acids into the cell. This study demonstrates the use of TALENs for targeted engineering of yeast and demonstrates that this technology can be used to stimulate the enhanced production of free fatty acids, which are potential substrates for biofuel production. This proof-of-principle study extends the utility of TALENs as excellent genome editing tools and highlights their potential use for metabolic engineering of yeast and other organisms, such as microalgae and plants, for biofuel production.

  8. [Bacteriocins produced by lactic acid bacteria].

    Science.gov (United States)

    Bilková, Andrea; Sepova, Hana Kinová; Bilka, Frantisek; Balázová, Andrea

    2011-04-01

    Lactic acid bacteria comprise several genera of gram-positive bacteria that are known for the production of structurally different antimicrobial substances. Among them, bacteriocins are nowadays in the centre of scientific interest. Bacteriocins, proteinaceous antimicrobial substances, are produced ribosomally and have usually a narrow spectrum of bacterial growth inhibition. According to their structure and the target of their activity, they are divided into four classes, although there are some suggestions for a renewed classification. The most interesting and usable class are lantibiotics. They comprise the most widely commercially used and well examined bacteriocin, nisin. The non-pathogenic character of lactic acid bacteria is advantageous for using their bacteriocins in food preservation as well as in feed supplements or in veterinary medicine.

  9. Production of D-lactic acid in a continuous membrane integrated fermentation reactor by genetically modified Saccharomyces cerevisiae: enhancement in D-lactic acid carbon yield.

    Science.gov (United States)

    Mimitsuka, Takashi; Sawai, Kenji; Kobayashi, Koji; Tsukada, Takeshi; Takeuchi, Norihiro; Yamada, Katsushige; Ogino, Hiroyasu; Yonehara, Tetsu

    2015-01-01

    Poly d-lactic acid is an important polymer because it improves the thermostability of poly l-lactic acid by stereo complex formation. To demonstrate potency of continuous fermentation using a membrane-integrated fermentation reactor (MFR) system, continuous fermentation using genetically modified Saccharomyces cerevisiae which produces d-lactic acid was performed at the low pH and microaerobic conditions. d-Lactic acid continuous fermentation using the MFR system by genetically modified yeast increased production rate by 11-fold compared with batch fermentation. In addition, the carbon yield of d-lactic acid in continuous fermentation was improved to 74.6 ± 2.3% compared to 39.0 ± 1.7% with batch fermentation. This dramatic improvement in carbon yield could not be explained by a reduction in carbon consumption to form cells compared to batch fermentation. Further detailed analysis at batch fermentation revealed that the carbon yield increased to 76.8% at late stationary phase. S. cerevisiae, which exhibits the Crabtree-positive effect, demonstrated significant changes in metabolic activities at low sugar concentrations (Rossignol et al., Yeast, 20, 1369-1385, 2003). Moreover, lactate-producing S. cerevisiae requires ATP supplied not only from the glycolytic pathway but also from the TCA cycle (van Maris et al., Appl. Environ. Microbiol., 70, 2898-2905, 2004). Our finding was revealed that continuous fermentation, which can maintain the conditions of both a low sugar concentration and air supply, results in Crabtree-positive and lactate-producing S. cerevisiae for suitable conditions of d-lactic acid production with respect to redox balance and ATP generation because of releasing the yeast from the Crabtree effect.

  10. Integrated phospholipidomics and transcriptomics analysis of Saccharomyces cerevisiae with enhanced tolerance to a mixture of acetic acid, furfural, and phenol

    Science.gov (United States)

    A mixture of acetic acid, furfural and phenol (AFP), three representative lignocellulose derived inhibitors, significantly inhibited the growth and bioethanol production of Saccharomyces cerevisiae. In order to uncover mechanisms behind the enhanced tolerance of an inhibitor-tolerant S.cerevisiae s...

  11. The sequence diversity and expression among genes of the folic acid biosynthesis pathway in industrial Saccharomyces strains.

    Science.gov (United States)

    Goncerzewicz, Anna; Misiewicz, Anna

    2015-01-01

    Folic acid is an important vitamin in human nutrition and its deficiency in pregnant women's diets results in neural tube defects and other neurological damage to the fetus. Additionally, DNA synthesis, cell division and intestinal absorption are inhibited in case of adults. Since this discovery, governments and health organizations worldwide have made recommendations concerning folic acid supplementation of food for women planning to become pregnant. In many countries this has led to the introduction of fortifications, where synthetic folic acid is added to flour. It is known that Saccharomyces strains (brewing and bakers' yeast) are one of the main producers of folic acid and they can be used as a natural source of this vitamin. Proper selection of the most efficient strains may enhance the folate content in bread, fermented vegetables, dairy products and beer by 100% and may be used in the food industry. The objective of this study was to select the optimal producing yeast strain by determining the differences in nucleotide sequences in the FOL2, FOL3 and DFR1 genes of folic acid biosynthesis pathway. The Multitemperature Single Strand Conformation Polymorphism (MSSCP) method and further nucleotide sequencing for selected strains were applied to indicate SNPs in selected gene fragments. The RT qPCR technique was also applied to examine relative expression of the FOL3 gene. Furthermore, this is the first time ever that industrial yeast strains were analysed regarding genes of the folic acid biosynthesis pathway. It was observed that a correlation exists between the folic acid amount produced by industrial yeast strains and changes in the nucleotide sequence of adequate genes. The most significant changes occur in the DFR1 gene, mostly in the first part, which causes major protein structure modifications in KKP 232, KKP 222 and KKP 277 strains. Our study shows that the large amount of SNP contributes to impairment of the selected enzymes and S. cerevisiae and S

  12. Terminal acidic shock inhibits sour beer bottle conditioning by Saccharomyces cerevisiae.

    Science.gov (United States)

    Rogers, Cody M; Veatch, Devon; Covey, Adam; Staton, Caleb; Bochman, Matthew L

    2016-08-01

    During beer fermentation, the brewer's yeast Saccharomyces cerevisiae experiences a variety of shifting growth conditions, culminating in a low-oxygen, low-nutrient, high-ethanol, acidic environment. In beers that are bottle conditioned (i.e., carbonated in the bottle by supplying yeast with a small amount of sugar to metabolize into CO2), the S. cerevisiae cells must overcome these stressors to perform the ultimate act in beer production. However, medium shock caused by any of these variables can slow, stall, or even kill the yeast, resulting in production delays and economic losses. Here, we describe a medium shock caused by high lactic acid levels in an American sour beer, which we refer to as "terminal acidic shock". Yeast exposed to this shock failed to bottle condition the beer, though they remained viable. The effects of low pH/high [lactic acid] conditions on the growth of six different brewing strains of S. cerevisiae were characterized, and we developed a method to adapt the yeast to growth in acidic beer, enabling proper bottle conditioning. Our findings will aid in the production of sour-style beers, a trending category in the American craft beer scene.

  13. Comparative proteomic analysis of engineered Saccharomyces cerevisiae with enhanced free fatty acid accumulation.

    Science.gov (United States)

    Chen, Liwei; Lee, Jaslyn Jie Lin; Zhang, Jianhua; Chen, Wei Ning

    2016-02-01

    The engineered Saccharomyces cerevisiae strain △faa1△faa4 [Acot5s] was demonstrated to accumulate more free fatty acids (FFA) previously. Here, comparative proteomic analysis was performed to get a global overview of metabolic regulation in the strain. Over 500 proteins were identified, and 82 of those proteins were found to change significantly in the engineered strains. Proteins involved in glycolysis, acetate metabolism, fatty acid synthesis, TCA cycle, glyoxylate cycle, the pentose phosphate pathway, respiration, transportation, and stress response were found to be upregulated in △faa1△faa4 [Acot5s] as compared to the wild type. On the other hand, proteins involved in glycerol, ethanol, ergosterol, and cell wall synthesis were downregulated. Taken together with our metabolite analysis, our results showed that the disruption of Faa1 and Faa4 and expression of Acot5s in the engineered strain △faa1△faa4 [Acot5s] not only relieved the feedback inhibition of fatty acyl-CoAs on fatty acid synthesis, but also caused a major metabolic rearrangement. The rearrangement redirected carbon flux toward the pathways which generate the essential substrates and cofactors for fatty acid synthesis, such as acetyl-CoA, ATP, and NADPH. Therefore, our results help shed light on the mechanism for the increased production of fatty acids in the engineered strains, which is useful in providing information for future studies in biofuel production.

  14. Redundant Systems of Phosphatidic Acid Biosynthesis via Acylation of Glycerol-3-Phosphate or Dihydroxyacetone Phosphate in the Yeast Saccharomyces cerevisiae

    OpenAIRE

    Athenstaedt, Karin; Weys, Sabine; Paltauf, Fritz; Daum, Günther

    1999-01-01

    In the yeast Saccharomyces cerevisiae lipid particles harbor two acyltransferases, Gat1p and Slc1p, which catalyze subsequent steps of acylation required for the formation of phosphatidic acid. Both enzymes are also components of the endoplasmic reticulum, but this compartment contains additional acyltransferase(s) involved in the biosynthesis of phosphatidic acid (K. Athenstaedt and G. Daum, J. Bacteriol. 179:7611–7616, 1997). Using the gat1 mutant strain TTA1, we show here that Gat1p presen...

  15. IMMOBILIZATION OF Saccharomyces Cerevisiae USING POLY(ACRYLAMIDE) GEL FOR ASYMMETRIC SYNTHESIS OF R(-)-MANDELIC ACID

    Institute of Scientific and Technical Information of China (English)

    LI Zhongqin; GUO Daiping; HUANG Xinghua; YANG Kai; XU Xiaoping

    2006-01-01

    In this paper, the poly(acrylamide) hydrogel used to immobilize saccharomyces cerevisiae for asymmetric synthesis of R(-)-mandelic acid was prepared with free radical ploymerization in deionized water at room temperature under nitrogen atmosphere. The influence of the composition of hydrogel, loading amount of cells and culture conditions on the asymmetric synthesis was investigated. Results show that PAAm hydrogel is a feasible carrier for immobilization of cells which is a potential alternative method to prepare enantiomerically pure R(-)-mandelic acid.

  16. Scale-down of continuous protein producing Saccharomyces cerevisiae cultivations using a two compartment system

    DEFF Research Database (Denmark)

    Wright, Naia Risager; Rønnest, Nanna Petersen; Thykær, Jette

    2016-01-01

    In the biotechnological industry, economic decisions in investment are typically based on laboratory scale experiments. Scale-down as a tool is therefore of high industrial importance in order to transfer the processes into larger production scale without loss in performance. In this study large ....... Based on these results, it is argued that introduction of variations in substrate concentration can be beneficial for industrial continuous cultivations....... scale prolonged continuous cultivations with a heterologous protein producing Saccharomyces cerevisiae strain have been scaled-down to a two compartment scale-down reactor system. The effects of glucose, pH, and oxygen concentration gradients have been investigated by comparison with corresponding 300...... ml standard continuous cultivations. It was found that substrate gradients within a limited range result in increased productivity of the heterologous protein under regulation of the glycolytic TPI promoter and delay the decrease of protein and trehalose production during continuous cultivation...

  17. Development of bottom-fermenting saccharomyces strains that produce high SO2 levels, using integrated metabolome and transcriptome analysis.

    Science.gov (United States)

    Yoshida, Satoshi; Imoto, Jun; Minato, Toshiko; Oouchi, Rie; Sugihara, Mao; Imai, Takeo; Ishiguro, Tatsuji; Mizutani, Satoru; Tomita, Masaru; Soga, Tomoyoshi; Yoshimoto, Hiroyuki

    2008-05-01

    Sulfite plays an important role in beer flavor stability. Although breeding of bottom-fermenting Saccharomyces strains that produce high levels of SO(2) is desirable, it is complicated by the fact that undesirable H(2)S is produced as an intermediate in the same pathway. Here, we report the development of a high-level SO(2)-producing bottom-fermenting yeast strain by integrated metabolome and transcriptome analysis. This analysis revealed that O-acetylhomoserine (OAH) is the rate-limiting factor for the production of SO(2) and H(2)S. Appropriate genetic modifications were then introduced into a prototype strain to increase metabolic fluxes from aspartate to OAH and from sulfate to SO(2), resulting in high SO(2) and low H(2)S production. Spontaneous mutants of an industrial strain that were resistant to both methionine and threonine analogs were then analyzed for similar metabolic fluxes. One promising mutant produced much higher levels of SO(2) than the parent but produced parental levels of H(2)S.

  18. Identification of a Δ12 fatty acid desaturase from oil palm (Elaeis guineensis Jacq.) involved in the biosynthesis of linoleic acid by heterologous expression in Saccharomyces cerevisiae.

    Science.gov (United States)

    Sun, Ruhao; Gao, Lingchao; Yu, Xiaoping; Zheng, Yusheng; Li, Dongdong; Wang, Xinguang

    2016-10-10

    Oil palm (Elaeis guineensis Jacq.) is one of the highest oil-yield crops in the world. A Δ12-desaturases associated with the primary steps of long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis were successfully cloned from oil palm and their functions identified. The open reading frames (ORFs) of egFAD2 (GenBank accession: KT023602) consisted of 1176bp and code for 391 amino acids. Their deduced polypeptides showed 75-93% identity to microsomal Δ12-desaturases from other higher plants, and each contained the three histidine clusters typical of the catalytic domains of such enzymes. RT-PCR experiment indicated that the egFAD2 gene exhibited the highest accumulation in the mesocarp of fruits at 120-140 DAP (i.e. the fourth period of fruit development) and, despite having different expression levels, the other four stages were at significantly lower levels compared with the fourth stage. Plasmid pYES2-egFAD2 was transformed into Saccharomyces cerevisiae strain INVSc1 using lithium acetate method for expression under the induction of galactose. Yeast cells transformed with plasmid constructs containing egFAD12 produced an appreciable amount of linoleic acids (18:2(Δ9,)(12)), not normally present in wild-type yeast cells, indicating that the genes encoded functional Δ12-desaturase enzymes.

  19. Engineering of a Nepetalactol-Producing Platform Strain of Saccharomyces cerevisiae for the Production of Plant Seco-Iridoids.

    Science.gov (United States)

    Campbell, Alex; Bauchart, Philippe; Gold, Nicholas D; Zhu, Yun; De Luca, Vincenzo; Martin, Vincent J J

    2016-05-20

    The monoterpene indole alkaloids (MIAs) are a valuable family of chemicals that include the anticancer drugs vinblastine and vincristine. These compounds are of global significance-appearing on the World Health Organization's list of model essential medicines-but remain exorbitantly priced due to low in planta levels. Chemical synthesis and genetic manipulation of MIA producing plants such as Catharanthus roseus have so far failed to find a solution to this problem. Synthetic biology holds a potential answer, by building the pathway into more tractable organisms such as Saccharomyces cerevisiae. Recent work has taken the first steps in this direction by producing small amounts of the intermediate strictosidine in yeast. In order to help improve on these titers, we aimed to optimize the early biosynthetic steps of the MIA pathway to the metabolite nepetalactol. We combined a number of strategies to create a base strain producing 11.4 mg/L of the precursor geraniol. We also show production of the critical intermediate 10-hydroxygeraniol and demonstrate nepetalactol production in vitro. Lastly we demonstrate that activity of the iridoid synthase toward the intermediates geraniol and 10-hydroxygeraniol results in the synthesis of the nonproductive intermediates citronellol and 10-hydroxycitronellol. This discovery has serious implications for the reconstruction of the MIA in heterologous organisms.

  20. Inhibitory effects of gallic acid ester derivatives on Saccharomyces cerevisiae multidrug resistance protein Pdr5p.

    Science.gov (United States)

    Pereira Rangel, Luciana; Fritzen, Márcio; Yunes, Rosendo Augusto; Leal, Paulo César; Creczynski-Pasa, Tânia Beatriz; Ferreira-Pereira, Antônio

    2010-05-01

    Overexpression of the Saccharomyces cerevisiae ABC transporter Pdr5p confers resistance to a range of structurally unrelated xenobiotics. This property allows Pdr5p to be used as a target for novel multidrug resistance reversal reagents or chemosensitizers. Herein, we report the effects of gallic acid derivatives with substitutions either on the ester moiety or in the benzene ring on the activity of Pdr5p. Compounds with a longer side chain (8-16 carbons) resulted in greater inhibition of Pdr5p ATPase. Derivatives with side chains of 8-12 carbons that retained hydroxyl groups on the benzene ring extensively inhibited Pdr5p ATPase activity. These compounds almost completely inhibited the efflux of the Pdr5p fluorescent substrate Rhodamine 6G and at 25 muM chemosensitized the Pdr5p-overexpressing strain AD124567 to fluconazole (0.4 mg mL(-1)). Gallic acid derivatives may be a new class of Pdr5p inhibitors.

  1. Promoter strength of folic acid synthesis genes affects sulfa drug resistance in Saccharomyces cerevisiae.

    Science.gov (United States)

    Iliades, Peter; Berglez, Janette; Meshnick, Steven; Macreadie, Ian

    2003-01-01

    The enzyme dihydropteroate synthase (DHPS) is an important target for sulfa drugs in both prokaryotic and eukaryotic microbes. However, the understanding of DHPS function and the action of antifolates in eukaryotes has been limited due to technical difficulties and the complexity of DHPS being a part of a bifunctional or trifunctional protein that comprises the upstream enzymes involved in folic acid synthesis (FAS). Here, yeast strains have been constructed to study the effects of FOL1 expression on growth and sulfa drug resistance. A DHPS knockout yeast strain was complemented by yeast vectors expressing the FOL1 gene under the control of promoters of different strengths. An inverse relationship was observed between the growth rate of the strains and FOL1 expression levels. The use of stronger promoters to drive FOL1 expression led to increased sulfamethoxazole resistance when para-aminobenzoic acid (pABA) levels were elevated. However, high FOL1 expression levels resulted in increased susceptibility to sulfamethoxazole in pABA free media. These data suggest that up-regulation of FOL1 expression can lead to sulfa drug resistance in Saccharomyces cerevisiae.

  2. Effect of Propanoic Acid on Ethanol Fermentation by Saccharomyces cerevisiae in an Ethanol-Methane Coupled Fermentation Process

    Institute of Scientific and Technical Information of China (English)

    张成明; 杜风光; 王欣; 毛忠贵; 孙沛勇; 唐蕾; 张建军

    2012-01-01

    Propanoic acid accumulated in an ethanol-methane coupled fermentation process affects the ethanol fermentation by Saccharomyces cerevisiae. The effects of propanoic acid on ethanol production were examined in cassava mash under different pH conditions. Final ethanol concentrations increased when undissociated propanoic acid was 〈30.0 mmol·L-1 . Propanoic acid, however, stimulated ethanol production, as much as 7.6% under proper conditions, but ethanol fermentation was completely inhibited when undissociated acid was 〉53.2 mmol·L-1 . Therefore, the potential inhibitory effect of propanoic acid on ethanol fermentation may be avoided by controlling the undissociated acid concentrations through elevated medium pH. Biomass and glycerol production decreased with propanoic acid in the medium, partly contributing to increased ethanol concentration.

  3. Potent L-lactic acid assimilation of the fermentative and heterothallic haploid yeast Saccharomyces cerevisiae NAM34-4C.

    Science.gov (United States)

    Tomitaka, Masataka; Taguchi, Hisataka; Matsuoka, Masayoshi; Morimura, Shigeru; Kida, Kenji; Akamatsu, Takashi

    2014-01-01

    We screened an industrial thermotolerant Saccharomyces cerevisiae strain, KF7, as a potent lactic-acid-assimilating yeast. Heterothallic haploid strains KF7-5C and KF7-4B were obtained from the tetrads of the homothallic yeast strain KF7. The inefficient sporulation and poor spore viability of the haploid strains were improved by two strategies. The first strategy was as follows: (i) the KF7-5C was crossed with the laboratory strain SH6710; (ii) the progenies were backcrossed with KF7-5C three times; and (iii) the progenies were inbred three times to maintain a genetic background close to that of KF7. The NAM12 diploid between the cross of the resultant two strains, NAM11-9C and NAM11-13A, showed efficient sporulation and exhibited excellent growth in YPD medium (pH 3.5) at 35°C with 1.4-h generation time, indicating thermotolerance and acid tolerance. The second strategy was successive intrastrain crosses. The resultant two strains, KFG4-6B and KFG4-4B, showed excellent mating capacity. A spontaneous mutant of KFG4-6B, KFG4-6BD, showed a high growth rate with a generation time of 1.1 h in YPD medium (pH 3.0) at 35°C. The KFG4-6BD strain produced ascospores, which were crossed with NAM11-2C and its progeny to produce tetrads. These tetrads were crossed with KFG4-4B to produce NAM26-14A and NAM26-15A. The latter strain had a generation time of 1.6 h at 35°C in pH 2.5, thus exhibiting further thermotolerance and acid tolerance. A progeny from a cross of NAM26-14A and NAM26-15A yielded the strain NAM34-4C, which showed potent lactic acid assimilation and high transformation efficiency, better than those of a standard laboratory strain.

  4. Lactic acid production from Cellobiose and xylose by engineered Saccharomyces cerevisiae

    Science.gov (United States)

    Efficient and rapid production of value-added chemicals from lignocellulosic biomass is an important step towards a sustainable society. Lactic acid, used for synthesizing the bioplastic polylactide, has been produced by microbial fermentation using primarily glucose. Lignocellulosic hydrolysates co...

  5. Optimizing promoters and secretory signal sequences for producing ethanol from inulin by recombinant Saccharomyces cerevisiae carrying Kluyveromyces marxianus inulinase.

    Science.gov (United States)

    Hong, Soo-Jeong; Kim, Hyo Jin; Kim, Jin-Woo; Lee, Dae-Hee; Seo, Jin-Ho

    2015-02-01

    Inulin is a polyfructan that is abundant in plants such as Jerusalem artichoke, chicory and dahlia. Inulinase can easily hydrolyze inulin to fructose, which is consumed by microorganisms. Generally, Saccharomyces cerevisiae, an industrial workhorse strain for bioethanol production, is known for not having inulinase activity. The inulinase gene from Kluyveromyces marxianus (KmINU), with the ability of converting inulin to fructose, was introduced into S. cerevisiae D452-2. The inulinase gene was fused to three different types of promoter (GPD, PGK1, truncated HXT7) and secretory signal sequence (KmINU, MFα1, SUC2) to generate nine expression cassettes. The inulin fermentation performance of the nine transformants containing different promoter and signal sequence combinations for inulinase production were compared to select an optimized expression system for efficient inulin fermentation. Among the nine inulinase-producing transformants, the S. cerevisiae carrying the PGK1 promoter and MFα1 signal sequence (S. cerevisiae D452-2/p426PM) showed not only the highest specific KmINU activity, but also the best inulin fermentation capability. Finally, a batch fermentation of the selected S. cerevisiae D452-2/p426PM in a bioreactor with 188.2 g/L inulin was performed to produce 80.2 g/L ethanol with 0.43 g ethanol/g inulin of ethanol yield and 1.22 g/L h of ethanol productivity.

  6. Evaluation of Brachypodium distachyon L-Tyrosine Decarboxylase Using L-Tyrosine Over-Producing Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Shuhei Noda

    Full Text Available To demonstrate that herbaceous biomass is a versatile gene resource, we focused on the model plant Brachypodium distachyon, and screened the B. distachyon for homologs of tyrosine decarboxylase (TDC, which is involved in the modification of aromatic compounds. A total of 5 candidate genes were identified in cDNA libraries of B. distachyon and were introduced into Saccharomyces cerevisiae to evaluate TDC expression and tyramine production. It is suggested that two TDCs encoded in the transcripts Bradi2g51120.1 and Bradi2g51170.1 have L-tyrosine decarboxylation activity. Bradi2g51170.1 was introduced into the L-tyrosine over-producing strain of S. cerevisiae that was constructed by the introduction of mutant genes that promote deregulated feedback inhibition. The amount of tyramine produced by the resulting transformant was 6.6-fold higher (approximately 200 mg/L than the control strain, indicating that B. distachyon TDC effectively converts L-tyrosine to tyramine. Our results suggest that B. distachyon possesses enzymes that are capable of modifying aromatic residues, and that S. cerevisiae is a suitable host for the production of L-tyrosine derivatives.

  7. Influence of thermally processed carbohydrate/amino acid mixtures on the fermentation by Saccharomyces cerevisiae.

    Science.gov (United States)

    Tauer, Andreas; Elss, Sandra; Frischmann, Matthias; Tellez, Patricia; Pischetsrieder, Monika

    2004-04-07

    The production of alcoholic beverages such as Tequila, Mezcal, whiskey, or beer includes the fermentation of a mash containing Maillard reaction products. Because excessive heating of the mash can lead to complications during the following fermentation step, the impact of Maillard products on the metabolism of Saccharomyces cerevisiae was investigated. For this purpose, fermentation was carried out in a model system in the presence and absence of Maillard reaction products and formation of ethanol served as a marker for the progression of fermentation. We found that increasing amounts of Maillard products reduced the formation of ethanol up to 80%. This effect was dependent on the pH value during the Maillard reaction, reaction time, as well as the carbohydrate and amino acid component used for the generation of Maillard reaction products. Another important factor is the pH value during fermentation: The inhibitory effect of Maillard products was not detectable at a pH of 4 and increased with higher pH-values. These findings might be of relevance for the production of above-mentioned beverages.

  8. Metabolic engineering of Saccharomyces cerevisiae for the overproduction of short branched-chain fatty acids.

    Science.gov (United States)

    Yu, Ai-Qun; Juwono, Nina Kurniasih Pratomo; Foo, Jee Loon; Leong, Susanna Su Jan; Chang, Matthew Wook

    2016-03-01

    Short branched-chain fatty acids (SBCFAs, C4-6) are versatile platform intermediates for the production of value-added products in the chemical industry. Currently, SBCFAs are mainly synthesized chemically, which can be costly and may cause environmental pollution. In order to develop an economical and environmentally friendly route for SBCFA production, we engineered Saccharomyces cerevisiae, a model eukaryotic microorganism of industrial significance, for the overproduction of SBCFAs. In particular, we employed a combinatorial metabolic engineering approach to optimize the native Ehrlich pathway in S. cerevisiae. First, chromosome-based combinatorial gene overexpression led to a 28.7-fold increase in the titer of SBCFAs. Second, deletion of key genes in competing pathways improved the production of SBCFAs to 387.4 mg/L, a 31.2-fold increase compared to the wild-type. Third, overexpression of the ATP-binding cassette (ABC) transporter PDR12 increased the secretion of SBCFAs. Taken together, we demonstrated that the combinatorial metabolic engineering approach used in this study effectively improved SBCFA biosynthesis in S. cerevisiae through the incorporation of a chromosome-based combinatorial gene overexpression strategy, elimination of genes in competitive pathways and overexpression of a native transporter. We envision that this strategy could also be applied to the production of other chemicals in S. cerevisiae and may be extended to other microbes for strain improvement.

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

    Directory of Open Access Journals (Sweden)

    Kanchana R. Kildegaard

    2015-12-01

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

  10. Valproic acid- and lithium-sensitivity in prs mutants of Saccharomyces cerevisiae.

    Science.gov (United States)

    Kleineidam, Anna; Vavassori, Stefano; Wang, Ke; Schweizer, Lilian M; Griac, Peter; Schweizer, Michael

    2009-10-01

    Prs [PRPP (phosphoribosyl pyrophosphate) synthetase] catalyses the transfer of pyrophosphate from ATP to ribose 5-phosphate, thereby activating the pentose sugar for incorporation into purine and pyrimidine nucleotides. The Saccharomyces cerevisiae genome contains five genes, PRS1-PRS5, whose products display characteristic PRPP and bivalent-cation-binding sites of Prs polypeptides. Deletion of one or more of the five PRS genes has far-reaching and unexpected consequences, e.g. impaired cell integrity, temperature-sensitivity and sensitivity to VPA (valproic acid) and LiCl. CTP pools in prs1Delta and prs3Delta are reduced to 12 and 31% of the wild-type respectively, resulting in an imbalance in phospholipid metabolism which may have an impact on the intracellular inositol pool which is affected by the administration of either VPA or LiCl. Overexpression of CTP synthetase in prs1Delta prs3Delta strains partially reverses the VPA-sensitive phenotype. Yeast two-hybrid screening revealed that Prs3 and the yeast orthologue of GSK3 (glycogen synthase kinase 3), Rim11, a serine/threonine kinase involved in several signalling pathways, interact with each other. Furthermore, Prs5, an essential partner of Prs3, which also interacts with GSK3 contains three neighbouring phosphorylation sites, typical of GSK3 activation. These studies on yeast PRPP synthetases bring together and expand the current theories for the mood-stabilizing effects of VPA and LiCl in bipolar disorder.

  11. Identification of Genes in Saccharomyces cerevisiae that Are Haploinsufficient for Overcoming Amino Acid Starvation

    Directory of Open Access Journals (Sweden)

    Nancy S. Bae

    2017-04-01

    Full Text Available The yeast Saccharomyces cerevisiae responds to amino acid deprivation by activating a pathway conserved in eukaryotes to overcome the starvation stress. We have screened the entire yeast heterozygous deletion collection to identify strains haploinsufficient for growth in the presence of sulfometuron methyl, which causes starvation for isoleucine and valine. We have discovered that cells devoid of MET15 are sensitive to sulfometuron methyl, and loss of heterozygosity at the MET15 locus can complicate screening the heterozygous deletion collection. We identified 138 cases of loss of heterozygosity in this screen. After eliminating the issues of the MET15 loss of heterozygosity, strains isolated from the collection were retested on sulfometuron methyl. To determine the general effect of the mutations for a starvation response, SMM-sensitive strains were tested for the ability to grow in the presence of canavanine, which induces arginine starvation, and strains that were MET15 were also tested for growth in the presence of ethionine, which causes methionine starvation. Many of the genes identified in our study were not previously identified as starvation-responsive genes, including a number of essential genes that are not easily screened in a systematic way. The genes identified span a broad range of biological functions, including many involved in some level of gene expression. Several unnamed proteins have also been identified, giving a clue as to possible functions of the encoded proteins.

  12. Metabolic Engineering of Yeast to Produce Fatty Acid-derived Biofuels: Bottlenecks and Solutions

    Directory of Open Access Journals (Sweden)

    Jiayuan eSheng

    2015-06-01

    Full Text Available Fatty acid-derived biofuels can be a better solution than bioethanol to replace petroleum fuel, since they have similar energy content and combustion properties as current transportation fuels. The environmentally friendly microbial fermentation process has been used to synthesize advanced biofuels from renewable feedstock. Due to their robustness as well as the high tolerance to fermentation inhibitors and phage contamination, yeast strains such as Saccharomyces cerevisiae and Yarrowia lipolytica have attracted tremendous attention in recent studies regarding the production of fatty acid-derived biofuels, including fatty acids, fatty acid ethyl esters, fatty alcohols, and fatty alkanes. However, the native yeast strains cannot produce fatty acids and fatty acid-derived biofuels in large quantities. To this end, we have summarized recent publications in this review on metabolic engineering of yeast strains to improve the production of fatty acid-derived biofuels, identified the bottlenecks that limit the productivity of biofuels, and categorized the appropriate approaches to overcome these obstacles.

  13. Development of Saccharomyces cerevisiae producing higher levels of sulfur dioxide and glutathione to improve beer flavor stability.

    Science.gov (United States)

    Chen, Yefu; Yang, Xu; Zhang, Shijie; Wang, Xiaoqiong; Guo, Changhui; Guo, Xuewu; Xiao, Dongguang

    2012-01-01

    Sulfur compounds, such as sulfite (SO(2)), hydrogen sulfide (H(2)S), and glutathione (GSH), play different roles in beer flavor stability. SO(2) and GSH have antiaging effects which are helpful to improve the flavor stability of beer, whereas H(2)S is undesirable to beer flavor because of its unpleasant aroma. Here, we report the development of Saccharomyces cerevisiae which produces higher levels of SO(2) and GSH but lower level of H(2)S to improve beer flavor stability by nongenetic engineering approaches. After two rounds of UV mutagenesis coupled with specific plate screening methods, one promising mutant named MV16 was obtained. Compared with the original strain, the SO(2) and GSH production of MV16 in fermenting liquor increased by 31% and 30.2%, respectively, while H(2)S content decreased by 74.9%, and the DPPH radical clearance and the resistance staling value of beer fermented by MV16 increased by 24.6% and 33.0%, respectively. The antioxidizability of the mutant was improved significantly. The strategy adopted in our study could be used to obtain S. cerevisiae of improved antiaging properties, and the mutant would be safe for public use.

  14. Metabolic engineering of Saccharomyces cerevisiae microbial cell factories for succinic acid production

    DEFF Research Database (Denmark)

    Otero, José Manuel; Olsson, Lisbeth; Nielsen, Jens

    2007-01-01

    products is 18, 14, 54, and 9 C-mol/C-mol-glucose, respectively, with acids, encompassing fumaric, malic, and succinic acid. Succinic acid is a key building block molecule...... for further conversion to precursor molecules such as tetrahydrofuran, 1,4-butanediol, and butyrolactone. Succinic acid has the potential to become a commodity chemical, with world-wide annual demand exceeding $2 billion USD and over 160 million kg currently produced from petrochemical conversion of maleic...... anhydride. There are several biomass platforms, all prokaryotic, for succinic acid production; however, overproduction of succinic acid in S. cerevisiae offers distinct process advantages. For example, S. cerevisiae has been awarded GRAS status for use in human consumables, grows well at low p...

  15. Improved Acetic Acid Resistance in Saccharomyces cerevisiae by Overexpression of the WHI2 Gene Identified through Inverse Metabolic Engineering.

    Science.gov (United States)

    Chen, Yingying; Stabryla, Lisa; Wei, Na

    2016-01-29

    Development of acetic acid-resistant Saccharomyces cerevisiae is important for economically viable production of biofuels from lignocellulosic biomass, but the goal remains a critical challenge due to limited information on effective genetic perturbation targets for improving acetic acid resistance in the yeast. This study employed a genomic-library-based inverse metabolic engineering approach to successfully identify a novel gene target, WHI2 (encoding a cytoplasmatic globular scaffold protein), which elicited improved acetic acid resistance in S. cerevisiae. Overexpression of WHI2 significantly improved glucose and/or xylose fermentation under acetic acid stress in engineered yeast. The WHI2-overexpressing strain had 5-times-higher specific ethanol productivity than the control in glucose fermentation with acetic acid. Analysis of the expression of WHI2 gene products (including protein and transcript) determined that acetic acid induced endogenous expression of Whi2 in S. cerevisiae. Meanwhile, the whi2Δ mutant strain had substantially higher susceptibility to acetic acid than the wild type, suggesting the important role of Whi2 in the acetic acid response in S. cerevisiae. Additionally, overexpression of WHI2 and of a cognate phosphatase gene, PSR1, had a synergistic effect in improving acetic acid resistance, suggesting that Whi2 might function in combination with Psr1 to elicit the acetic acid resistance mechanism. These results improve our understanding of the yeast response to acetic acid stress and provide a new strategy to breed acetic acid-resistant yeast strains for renewable biofuel production.

  16. Plasma membrane proteins Yro2 and Mrh1 are required for acetic acid tolerance in Saccharomyces cerevisiae.

    Science.gov (United States)

    Takabatake, Akiko; Kawazoe, Nozomi; Izawa, Shingo

    2015-03-01

    Yro2 and its paralogous protein Mrh1 of Saccharomyces cerevisiae have seven predicted transmembrane domains and predominantly localize to the plasma membrane. Their physiological functions and regulation of gene expression have not yet been elucidated in detail. We herein demonstrated that MRH1 was constitutively expressed, whereas the expression of YRO2 was induced by acetic acid stress and entering the stationary phase. Fluorescence microscopic analysis revealed that Mrh1 and Yro2 were distributed as small foci in the plasma membrane under acetic acid stress conditions. The null mutants of these genes (mrh1∆, yro2∆, and mrh1∆yro2∆) showed delayed growth and a decrease in the productivity of ethanol in the presence of acetic acid, indicating that Yro2 and Mrh1 are involved in tolerance to acetic acid stress.

  17. Biologically produced succinic acid: A new route to chemical intermediates

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-09-01

    The national laboratory consortium has undertaken an R&D project with the Michigan Biotechnology Institute (MBI) to demonstrate the feasibility of producing a chemical intermediate, succinic acid, and various derivatives, from renewable agricultural resources. The projects near-term goal is to demonstrate an economically competetive process for producing 1,4-butanediol and other derivatives from biologically produced succinic acid without generating a major salt waste. The competitiveness to the petrochemical process must be demonstrated.

  18. Batch and continuous culture-based selection strategies for acetic acid tolerance in xylose-fermenting Saccharomyces cerevisiae.

    Science.gov (United States)

    Wright, Jeremiah; Bellissimi, Eleonora; de Hulster, Erik; Wagner, Andreas; Pronk, Jack T; van Maris, Antonius J A

    2011-05-01

    Acetic acid tolerance of Saccharomyces cerevisiae is crucial for the production of bioethanol and other bulk chemicals from lignocellulosic plant-biomass hydrolysates, especially at a low pH. This study explores two evolutionary engineering strategies for the improvement of acetic acid tolerance of the xylose-fermenting S. cerevisiae RWB218, whose anaerobic growth on xylose at pH 4 is inhibited at acetic acid concentrations >1 g L(-1) : (1) sequential anaerobic, batch cultivation (pH 4) at increasing acetic acid concentrations and (2) prolonged anaerobic continuous cultivation without pH control, in which acidification by ammonium assimilation generates selective pressure for acetic acid tolerance. After c. 400 generations, the sequential-batch and continuous selection cultures grew on xylose at pH≤4 with 6 and 5 g L(-1) acetic acid, respectively. In the continuous cultures, the specific xylose-consumption rate had increased by 75% to 1.7 g xylose g(-1) biomass h(-1) . After storage of samples from both selection experiments at -80 °C and cultivation without acetic acid, they failed to grow on xylose at pH 4 in the presence of 5 g L(-1) acetic acid. Characterization in chemostat cultures with linear acetic acid gradients demonstrated an acetate-inducible acetic acid tolerance in samples from the continuous selection protocol.

  19. Involvement of vacuolar sequestration and active transport in tolerance of Saccharomyces cerevisiae to hop iso-alpha-acids.

    Science.gov (United States)

    Hazelwood, Lucie A; Walsh, Michael C; Pronk, Jack T; Daran, Jean-Marc

    2010-01-01

    The hop plant, Humulus lupulus L., has an exceptionally high content of secondary metabolites, the hop alpha-acids, which possess a range of beneficial properties, including antiseptic action. Studies performed on the mode of action of hop iso-alpha-acids have hitherto been restricted to lactic acid bacteria. The present study investigated molecular mechanisms of hop iso-alpha-acid resistance in the model eukaryote Saccharomyces cerevisiae. Growth inhibition occurred at concentrations of hop iso-alpha-acids that were an order of magnitude higher than those found with hop-tolerant prokaryotes. Chemostat-based transcriptome analysis and phenotype screening of the S. cerevisiae haploid gene deletion collection were used as complementary methods to screen for genes involved in hop iso-alpha-acid detoxification and tolerance. This screening and further analysis of deletion mutants confirmed that yeast tolerance to hop iso-alpha-acids involves three major processes, active proton pumping into the vacuole by the vacuolar-type ATPase to enable vacuolar sequestration of iso-alpha-acids and alteration of cell wall structure and, to a lesser extent, active export of iso-alpha-acids across the plasma membrane. Furthermore, iso-alpha-acids were shown to affect cellular metal homeostasis by acting as strong zinc and iron chelators.

  20. Disruption of the Saccharomyces cerevisiae homologue to the murine fatty acid transport protein impairs uptake and growth on long-chain fatty acids

    DEFF Research Database (Denmark)

    Færgeman, Nils J.; DiRusso, C C; Elberger, A;

    1997-01-01

    described in 3T3-L1 adipocytes (Schaffer and Lodish (1994) Cell 79, 427-436), suggesting a similar function. Disruption of FAT1 results in 1) an impaired growth in YPD medium containing 25 microM cerulenin and 500 microM fatty acid (myristate (C14:0), palmitate (C16:0), or oleate (C18:1)); 2) a marked......The yeast Saccharomyces cerevisiae is able to utilize exogenous fatty acids for a variety of cellular processes including beta-oxidation, phospholipid biosynthesis, and protein modification. The molecular mechanisms that govern the uptake of these compounds in S. cerevisiae have not been described....... We report the characterization of FAT1, a gene that encodes a putative membrane-bound long-chain fatty acid transport protein (Fat1p). Fat1p contains 623 amino acid residues that are 33% identical and 54% with similar chemical properties as compared with the fatty acid transport protein FATP...

  1. Effects of acetic acid on the kinetics of xylose fermentation by an engineered, xylose-isomerase-based Saccharomyces cerevisiae strain.

    Science.gov (United States)

    Bellissimi, Eleonora; van Dijken, Johannes P; Pronk, Jack T; van Maris, Antonius J A

    2009-05-01

    Acetic acid, an inhibitor released during hydrolysis of lignocellulosic feedstocks, has previously been shown to negatively affect the kinetics and stoichiometry of sugar fermentation by (engineered) Saccharomyces cerevisiae strains. This study investigates the effects of acetic acid on S. cerevisiae RWB 218, an engineered xylose-fermenting strain based on the Piromyces XylA (xylose isomerase) gene. Anaerobic batch cultures on synthetic medium supplemented with glucose-xylose mixtures were grown at pH 5 and 3.5, with and without addition of 3 g L(-1) acetic acid. In these cultures, consumption of the sugar mixtures followed a diauxic pattern. At pH 5, acetic acid addition caused increased glucose consumption rates, whereas specific xylose consumption rates were not significantly affected. In contrast, at pH 3.5 acetic acid had a strong and specific negative impact on xylose consumption rates, which, after glucose depletion, slowed down dramatically, leaving 50% of the xylose unused after 48 h of fermentation. Xylitol production was absent (fermentation in acetic -acid-stressed cultures at pH 3.5 could be restored by applying a continuous, limiting glucose feed, consistent with a key role of ATP regeneration in acetic acid tolerance.

  2. Establishing a synthetic pathway for high-level production of 3-hydroxypropionic acid in Saccharomyces cerevisiae via β-alanine

    DEFF Research Database (Denmark)

    Borodina, Irina; Kildegaard, Kanchana Rueksomtawin; Jensen, Niels Bjerg

    2015-01-01

    Microbial fermentation of renewable feedstocks into plastic monomers can decrease our fossil dependence and reduce global CO2 emissions. 3-Hydroxypropionic acid (3HP) is a potential chemical building block for sustainable production of superabsorbent polymers and acrylic plastics. With the object......Microbial fermentation of renewable feedstocks into plastic monomers can decrease our fossil dependence and reduce global CO2 emissions. 3-Hydroxypropionic acid (3HP) is a potential chemical building block for sustainable production of superabsorbent polymers and acrylic plastics....... With the objective of developing Saccharomyces cerevisiae as an efficient cell factory for highlevel production of 3HP, we identified the ß-alanine biosynthetic route as the most economically attractive according to the metabolic modeling. We engineered and optimized a synthetic pathway for de novo biosynthesis of ß...

  3. Candida albicans and Saccharomyces cerevisiae induce interleukin-8 production from intestinal epithelial-like Caco-2 cells in the presence of butyric acid.

    Science.gov (United States)

    Saegusa, Shizue; Totsuka, Mamoru; Kaminogawa, Shuichi; Hosoi, Tomohiro

    2004-07-01

    Intestinal epithelial cells (IEC) are important in initiation and regulation of immune responses against numerous foreign substances including food, microorganisms and their metabolites in the intestine. Since the responses of IEC against yeasts have not yet been well understood, we investigated the effects of Candida albicans, Saccharomyces cerevisiae, and their cell wall components on interleukin-8 (IL-8) secretion by the IEC-like Caco-2 cells. Live cells of both yeast species stimulated Caco-2 cells to produce IL-8 only in the presence of butyric acid, which is a metabolite produced by intestinal bacteria. S. cerevisiae zymosan and glucan also enhanced IL-8 secretion. Treatment of Caco-2 cells with butyric acid increased the expression of mRNAs coding for Toll-like receptor 1 (TLR1), TLR6 and dectin-1, which recognize zymosan. C. albicans induced more IL-8 secretion and also decreased transepithelial electrical resistance more rapidly than S. cerevisiae. These results suggest that both yeasts in the intestine stimulate the host's mucosal immune systems by interacting with IEC.

  4. Lipidomic profiling of Saccharomyces cerevisiae and Zygosaccharomyces bailii reveals critical changes in lipid composition in response to acetic acid stress.

    Science.gov (United States)

    Lindberg, Lina; Santos, Aline Xs; Riezman, Howard; Olsson, Lisbeth; Bettiga, Maurizio

    2013-01-01

    When using microorganisms as cell factories in the production of bio-based fuels or chemicals from lignocellulosic hydrolysate, inhibitory concentrations of acetic acid, released from the biomass, reduce the production rate. The undissociated form of acetic acid enters the cell by passive diffusion across the lipid bilayer, mediating toxic effects inside the cell. In order to elucidate a possible link between lipid composition and acetic acid stress, the present study presents detailed lipidomic profiling of the major lipid species found in the plasma membrane, including glycerophospholipids, sphingolipids and sterols, in Saccharomyces cerevisiae (CEN.PK 113_7D) and Zygosaccharomyces bailii (CBS7555) cultured with acetic acid. Detailed physiological characterization of the response of the two yeasts to acetic acid has also been performed in aerobic batch cultivations using bioreactors. Physiological characterization revealed, as expected, that Z. bailii is more tolerant to acetic acid than S. cerevisiae. Z. bailii grew at acetic acid concentrations above 24 g L(-1), while limited growth of S. cerevisiae was observed after 11 h when cultured with only 12 g L(-1) acetic acid. Detailed lipidomic profiling using electrospray ionization, multiple-reaction-monitoring mass spectrometry (ESI-MRM-MS) showed remarkable changes in the glycerophospholipid composition of Z. bailii, including an increase in saturated glycerophospholipids and considerable increases in complex sphingolipids in both S. cerevisiae (IPC 6.2×, MIPC 9.1×, M(IP)2C 2.2×) and Z. bailii (IPC 4.9×, MIPC 2.7×, M(IP)2C 2.7×), when cultured with acetic acid. In addition, the basal level of complex sphingolipids was significantly higher in Z. bailii than in S. cerevisiae, further emphasizing the proposed link between lipid saturation, high sphingolipid levels and acetic acid tolerance. The results also suggest that acetic acid tolerance is associated with the ability of a given strain to generate large

  5. Lipidomic profiling of Saccharomyces cerevisiae and Zygosaccharomyces bailii reveals critical changes in lipid composition in response to acetic acid stress.

    Directory of Open Access Journals (Sweden)

    Lina Lindberg

    Full Text Available When using microorganisms as cell factories in the production of bio-based fuels or chemicals from lignocellulosic hydrolysate, inhibitory concentrations of acetic acid, released from the biomass, reduce the production rate. The undissociated form of acetic acid enters the cell by passive diffusion across the lipid bilayer, mediating toxic effects inside the cell. In order to elucidate a possible link between lipid composition and acetic acid stress, the present study presents detailed lipidomic profiling of the major lipid species found in the plasma membrane, including glycerophospholipids, sphingolipids and sterols, in Saccharomyces cerevisiae (CEN.PK 113_7D and Zygosaccharomyces bailii (CBS7555 cultured with acetic acid. Detailed physiological characterization of the response of the two yeasts to acetic acid has also been performed in aerobic batch cultivations using bioreactors. Physiological characterization revealed, as expected, that Z. bailii is more tolerant to acetic acid than S. cerevisiae. Z. bailii grew at acetic acid concentrations above 24 g L(-1, while limited growth of S. cerevisiae was observed after 11 h when cultured with only 12 g L(-1 acetic acid. Detailed lipidomic profiling using electrospray ionization, multiple-reaction-monitoring mass spectrometry (ESI-MRM-MS showed remarkable changes in the glycerophospholipid composition of Z. bailii, including an increase in saturated glycerophospholipids and considerable increases in complex sphingolipids in both S. cerevisiae (IPC 6.2×, MIPC 9.1×, M(IP2C 2.2× and Z. bailii (IPC 4.9×, MIPC 2.7×, M(IP2C 2.7×, when cultured with acetic acid. In addition, the basal level of complex sphingolipids was significantly higher in Z. bailii than in S. cerevisiae, further emphasizing the proposed link between lipid saturation, high sphingolipid levels and acetic acid tolerance. The results also suggest that acetic acid tolerance is associated with the ability of a given strain to

  6. Effect of fermentation with Saccharomyces cerevisiae strain PJ69-4 on the phytic acid, raffinose, and stachyose contents of soybean meal

    Science.gov (United States)

    Three experiments were conducted to determine the impact of submerged fermentation procedures using Saccharomyces cerevisiae baker’s yeast strain PJ69-4a on degradation of phytic acid and the raffinosaccharides, raffinose, and stachyose, in soybean meal. The goal of the research was to identify a n...

  7. Growth of catalase A and catalase T deficient mutant strains of Saccharomyces cerevisiae on ethanol and oleic acid : Growth profiles and catalase activities in relation to microbody proliferation

    NARCIS (Netherlands)

    Klei, Ida J. van der; Rytka, Joanna; Kunau, Wolf H.; Veenhuis, Marten

    1990-01-01

    The parental strain (A+T+) of Saccharomyces cerevisiae and mutants, deficient in catalase T (A+T-), catalase A (A-T+) or both catalases (A-T-), grew on ethanol and oleic acid with comparable doubling times. Specific activities of catalase were low in glucose- and ethanol-grown cells. In the two olei

  8. Amino acid residues important for substrate specificity of the amino acid permeases Can I p and Gnp I p in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Regenberg, Birgitte; Kielland-Brandt, M.C.

    2001-01-01

    Deletion of the general amino acid permease gene GAP1 abolishes uptake of L-citrulline in Saccharomyces cerevisiae, resulting in the inability to grow on L-citrulline as sole nitrogen source. Selection for suppressor mutants that restored growth on L-citrulline led to isolation of 21 mutations...... in the arginine permease gene CAN1. One similar mutation was found in the glutamine-asparagine permease gene GNP1. L-[C-14]citrulline uptake measurements confirmed that suppressor mutations in CAN1 conferred uptake of this amino acid, while none of the mutant permeases had lost the ability to transport L-[C-14......]arginine. Substrate specificity seemed to remain narrow in most cases, and broad substrate specificity was only observed in the cases where mutations affect two proline residues (P148 and P313) that are both conserved in the amino acid-polyamine-choline (APC) transporter superfamily. We found mutations...

  9. PEP3 overexpression shortens lag phase but does not alter growth rate in Saccharomyces cerevisiae exposed to acetic acid stress.

    Science.gov (United States)

    Ding, Jun; Holzwarth, Garrett; Bradford, C Samuel; Cooley, Ben; Yoshinaga, Allen S; Patton-Vogt, Jana; Abeliovich, Hagai; Penner, Michael H; Bakalinsky, Alan T

    2015-10-01

    In fungi, two recognized mechanisms contribute to pH homeostasis: the plasma membrane proton-pumping ATPase that exports excess protons and the vacuolar proton-pumping ATPase (V-ATPase) that mediates vacuolar proton uptake. Here, we report that overexpression of PEP3 which encodes a component of the HOPS and CORVET complexes involved in vacuolar biogenesis, shortened lag phase in Saccharomyces cerevisiae exposed to acetic acid stress. By confocal microscopy, PEP3-overexpressing cells stained with the vacuolar membrane-specific dye, FM4-64 had more fragmented vacuoles than the wild-type control. The stained overexpression mutant was also found to exhibit about 3.6-fold more FM4-64 fluorescence than the wild-type control as determined by flow cytometry. While the vacuolar pH of the wild-type strain grown in the presence of 80 mM acetic acid was significantly higher than in the absence of added acid, no significant difference was observed in vacuolar pH of the overexpression strain grown either in the presence or absence of 80 mM acetic acid. Based on an indirect growth assay, the PEP3-overexpression strain exhibited higher V-ATPase activity. We hypothesize that PEP3 overexpression provides protection from acid stress by increasing vacuolar surface area and V-ATPase activity and, hence, proton-sequestering capacity.

  10. Absence of Rtt109p, a fungal-specific histone acetyltransferase, results in improved acetic acid tolerance of Saccharomyces cerevisiae.

    Science.gov (United States)

    Cheng, Cheng; Zhao, Xinqing; Zhang, Mingming; Bai, Fengwu

    2016-03-01

    RTT109 is a histone acetyltransferase for the acetylation of histone H3. It is still not clear whether RTT109 plays a role in regulation of gene expression under environmental stresses. In this study, the involvement of RTT109 in acetic acid stress tolerance of Saccharomyces cerevisiae was investigated. It was revealed that the absence of RTT109 enhanced resistance to 5.5 g L(-1) acetic acid, which was indicated by improved growth of RTT109Δ mutant compared with that of the wild-type BY4741 strain. Meanwhile, the lag phase was shortened for 48 h and glucose consumption completed 36 h in advance for RTT109Δ mutant compared to the wild-type strain, with ethanol production rate increased from 0.39 to 0.60 g L(-1) h(-1). Significantly, elevated transcription levels of HSP12, CTT1 and GSH1, as well as increased activities of antioxidant enzymes were observed in RTT109Δ under acetic acid stress. Improved flocculation of RTT109Δ compared to that of the control strain BY4741 under the acetic acid stress was also observed. These results suggest that the absence of RTT109 not only activates transcription of stress responsive genes, but also improves resistance to oxidative stress, which ultimately contributes to improved acetic acid tolerance in S. cerevisiae.

  11. Availability of Amino Acids Extends Chronological Lifespan by Suppressing Hyper-Acidification of the Environment in Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Yo Maruyama

    Full Text Available The chronological lifespan of Saccharomyces cerevisiae represents the duration of cell survival in the postdiauxic and stationary phases. Using a prototrophic strain derived from the standard auxotrophic laboratory strain BY4742, we showed that supplementation of non-essential amino acids to a synthetic defined (SD medium increases maximal cell growth and extends the chronological lifespan. The positive effects of amino acids can be reproduced by modulating the medium pH, indicating that amino acids contribute to chronological longevity in a cell-extrinsic manner by alleviating medium acidification. In addition, we showed that the amino acid-mediated effects on extension of chronological longevity are independent of those achieved through a reduction in the TORC1 pathway, which is mediated in a cell-intrinsic manner. Since previous studies showed that extracellular acidification causes mitochondrial dysfunction and leads to cell death, our results provide a path to premature chronological aging caused by differences in available nitrogen sources. Moreover, acidification of culture medium is generally associated with culture duration and cell density; thus, further studies are required on cell physiology of auxotrophic yeast strains during the stationary phase because an insufficient supply of essential amino acids may cause alterations in environmental conditions.

  12. Aceitação e perfil sensorial das cachaças produzidas com Kefir e Saccharomyces cerevisae Acceptance and sensory profile of cachaça produced using Kefir and Saccharomyces cerevisae

    Directory of Open Access Journals (Sweden)

    Anita Saraiva Dornelles

    2009-09-01

    Full Text Available A levedura Saccharomyces cerevisae é o microrganismo mais utilizado industrialmente nas destilarias, mas outros microrganismos também são capazes de produzir etanol utilizando matérias-primas açucaradas como substrato. O objetivo deste trabalho foi determinar o perfil sensorial e a aceitação da aguardente de cana produzida através da fermentação alcoólica com grânulos de Kefir, comparando-a ao produto obtido tradicionalmente. Pelo método de ADQ, 8 provadores treinados avaliaram os seguintes descritores: aroma alcoólico e de cachaça, sabor alcoólico e de cachaça, gosto amargo e ardência. O teste de aceitação foi realizado por 57 consumidores de aguardente, utilizando-se uma escala hedônica estruturada de nove pontos para avaliar a aceitação do aroma e a aceitação global. A cachaça com Kefir apresentou maior intensidade de aroma alcoólico e gosto amargo, obtendo menor aceitação global que a cachaça de levedura. Dessa forma, o produto foi considerado de grande potencial visto que apresentou satisfatório percentual de aprovação entre os consumidores.Saccharomyces cerevisae is the main industrially used yeast to produce sugar cane spirits (cachaça. However, other microorganisms are able to produce ethanol using sugar as substrate. This work aimed at determining the sensory profile of cachaça produced through the alcoholic fermentation with Kefir's granules and its acceptance. The acceptance analysis was performed by 57 consumers using a 9 point structured hedonic scale to evaluate the aroma and the general acceptance of the product. The QDA method, with 8 trained tasters, was used to evaluate the following product descriptors: alcoholic aroma, alcoholic flavor, and burning and bitter taste. The evaluated samples did not presented statistical differences (p < 0.05 among each other regarding the aroma acceptance. However, the cachaça produced using bakery yeast presented higher acceptance scores. On the other hand

  13. Metabollic Engineering of Saccharomyces Cereviae a,omi acid metabolism for production of products of industrial interest

    DEFF Research Database (Denmark)

    Chen, Xiao

    Saccharomyces cerevisiae is widely used in microbial production of chemicals, metabolites and proteins, mainly because genetic manipulation of S. cerevisiae is relatively easy and experiences from its wide application in the existing industrial fermentations directly benefit new S. cerevisiae-based...... processes. This study has focused on metabolic engineering of the amino acid metabolism in S. cerevisiae for production of two types of chemicals of industrial interest. The first chemical is δ-(L-α-aminoadipyl)–L-cysteinyl–D-valine (LLD-ACV). ACV belongs to non-ribosomal peptides (NRPs), which......, by simultaneous overexpression of biosynthetic genes ILV2, ILV3, and ILV5 in valine metabolism in S. cerevisiae, the isobutanol yield was improved from 0.16 to 0.97 mg per g glucose in anaerobic fermentation in mineral medium. Isobutanol yield was further improved by two times by the additional overexpression...

  14. High ethanol fermentation performance of the dry dilute acid pretreated corn stover by an evolutionarily adapted Saccharomyces cerevisiae strain.

    Science.gov (United States)

    Qureshi, Abdul Sattar; Zhang, Jian; Bao, Jie

    2015-01-01

    Ethanol fermentation was investigated at the high solids content of the dry dilute sulfuric acid pretreated corn stover feedstock using an evolutionary adapted Saccharomyces cerevisiae DQ1 strain. The evolutionary adaptation was conducted by successively transferring the S. cerevisiae DQ1 cells into the inhibitors containing corn stover hydrolysate every 12h and finally a stable yeast strain was obtained after 65 days' continuous adaptation. The ethanol fermentation performance using the adapted strain was significantly improved with the high ethanol titer of 71.40 g/L and the high yield of 80.34% in the simultaneous saccharification and fermentation (SSF) at 30% solids content. No wastewater was generated from pretreatment to fermentation steps. The results were compared with the published cellulosic ethanol fermentation cases, and the obvious advantages of the present work were demonstrated not only at the high ethanol titer and yield, but also the significant reduction of wastewater generation and potential cost reduction.

  15. Cytokinin producing bacteria stimulate amino acid deposition by wheat roots.

    Science.gov (United States)

    Kudoyarova, Guzel R; Melentiev, Alexander I; Martynenko, Elena V; Timergalina, Leila N; Arkhipova, Tatiana N; Shendel, Galina V; Kuz'mina, Ludmila Yu; Dodd, Ian C; Veselov, Stanislav Yu

    2014-10-01

    Phytohormone production is one mechanism by which rhizobacteria can stimulate plant growth, but it is not clear whether the bacteria gain from this mechanism. The hypothesis that microbial-derived cytokinin phytohormones stimulate root exudation of amino acids was tested. The rhizosphere of wheat plants was drenched with the synthetic cytokinin trans-zeatin or inoculated with Bacillus subtilis IB-22 (which produces zeatin type cytokinins) or B. subtilis IB-21 (which failed to accumulate cytokinins). Growing plants in a split root system allowed spatial separation of zeatin application or rhizobacterial inoculation to one compartment and analyses of amino acid release from roots (rhizodeposition) into the other compartment (without either microbial inoculation or treatment with exogenous hormone). Supplying B. subtilis IB-22 or zeatin to either the whole root system or half of the roots increased concentrations of amino acids in the soil solution although the magnitude of the increase was greater when whole roots were treated. There was some similarity in amino acid concentrations induced by either bacterial or zeatin treatment. Thus B. subtilis IB-22 increased amino acid rhizodeposition, likely due to its ability to produce cytokinins. Furthermore, B. subtilis strain IB-21, which failed to accumulate cytokinins in culture media, did not significantly affect amino acid concentrations in the wheat rhizosphere. The ability of rhizobacteria to produce cytokinins and thereby stimulate rhizodeposition may be important in enhancing rhizobacterial colonization of the rhizoplane.

  16. Acetic acid inhibits nutrient uptake in Saccharomyces cerevisiae: auxotrophy confounds the use of yeast deletion libraries for strain improvement.

    Science.gov (United States)

    Ding, Jun; Bierma, Jan; Smith, Mark R; Poliner, Eric; Wolfe, Carole; Hadduck, Alex N; Zara, Severino; Jirikovic, Mallori; van Zee, Kari; Penner, Michael H; Patton-Vogt, Jana; Bakalinsky, Alan T

    2013-08-01

    Acetic acid inhibition of yeast fermentation has a negative impact in several industrial processes. As an initial step in the construction of a Saccharomyces cerevisiae strain with increased tolerance for acetic acid, mutations conferring resistance were identified by screening a library of deletion mutants in a multiply auxotrophic genetic background. Of the 23 identified mutations, 11 were then introduced into a prototrophic laboratory strain for further evaluation. Because none of the 11 mutations was found to increase resistance in the prototrophic strain, potential interference by the auxotrophic mutations themselves was investigated. Mutants carrying single auxotrophic mutations were constructed and found to be more sensitive to growth inhibition by acetic acid than an otherwise isogenic prototrophic strain. At a concentration of 80 mM acetic acid at pH 4.8, the initial uptake of uracil, leucine, lysine, histidine, tryptophan, phosphate, and glucose was lower in the prototrophic strain than in a non-acetic acid-treated control. These findings are consistent with two mechanisms by which nutrient uptake may be inhibited. Intracellular adenosine triphosphate (ATP) levels were severely decreased upon acetic acid treatment, which likely slowed ATP-dependent proton symport, the major form of transport in yeast for nutrients other than glucose. In addition, the expression of genes encoding some nutrient transporters was repressed by acetic acid, including HXT1 and HXT3 that encode glucose transporters that operate by facilitated diffusion. These results illustrate how commonly used genetic markers in yeast deletion libraries complicate the effort to isolate strains with increased acetic acid resistance.

  17. Improvement of acetic acid tolerance and fermentation performance of Saccharomyces cerevisiae by disruption of the FPS1 aquaglyceroporin gene.

    Science.gov (United States)

    Zhang, Jun-Guo; Liu, Xiu-Ying; He, Xiu-Ping; Guo, Xue-Na; Lu, Ying; Zhang, Bo-Run

    2011-02-01

    The FPS1 gene coding for the Fps1p aquaglyceroporin protein of an industrial strain of Saccharomyces cerevisiae was disrupted by inserting CUP1 gene. Wild-type strain, CE25, could only grow on YPD medium containing less than 0.45% (v/v) acetic acid, while recombinant strain T12 with FPS1 disruption could grow on YPD medium with 0.6% (v/v) acetic acid. Under 0.4% (v/v) acetic acid stress (pH 4.26), ethanol production and cell growth rates of T12 were 1.7 ± 0.1 and 0.061 ± 0.003 g/l h, while those of CE25 were 1.2 ± 0.1 and 0.048 ± 0.003 g/l h, respectively. FPS1 gene disruption in an industrial ethanologenic yeast thus increases cell growth and ethanol yield under acetic acid stress, which suggests the potential utility of FPS1 gene disruption for bioethanol production from renewable resources such as lignocelluloses.

  18. A glutamic acid-producing lactic acid bacteria isolated from Malaysian fermented foods.

    Science.gov (United States)

    Zareian, Mohsen; Ebrahimpour, Afshin; Bakar, Fatimah Abu; Mohamed, Abdul Karim Sabo; Forghani, Bita; Ab-Kadir, Mohd Safuan B; Saari, Nazamid

    2012-01-01

    l-glutamaic acid is the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism. In the present study, lactic acid bacteria (218) were isolated from six different fermented foods as potent sources of glutamic acid producers. The presumptive bacteria were tested for their ability to synthesize glutamic acid. Out of the 35 strains showing this capability, strain MNZ was determined as the highest glutamic-acid producer. Identification tests including 16S rRNA gene sequencing and sugar assimilation ability identified the strain MNZ as Lactobacillus plantarum. The characteristics of this microorganism related to its glutamic acid-producing ability, growth rate, glucose consumption and pH profile were studied. Results revealed that glutamic acid was formed inside the cell and excreted into the extracellular medium. Glutamic acid production was found to be growth-associated and glucose significantly enhanced glutamic acid production (1.032 mmol/L) compared to other carbon sources. A concentration of 0.7% ammonium nitrate as a nitrogen source effectively enhanced glutamic acid production. To the best of our knowledge this is the first report of glutamic acid production by lactic acid bacteria. The results of this study can be further applied for developing functional foods enriched in glutamic acid and subsequently γ-amino butyric acid (GABA) as a bioactive compound.

  19. New fermentation processes for producing itaconic acid and citric acid for industrial uses

    Science.gov (United States)

    Itaconic acid is an important industrial chemical that we have produced by fermentation of simple sugars using the yeast Pseudozyma antarctica. Itaconic acid is priced at ~$4 per kg and has an annual market volume of about 15,000 metric tons. Itaconic acid is used in the polymer industry and for m...

  20. Variations in mitochondrial membrane potential correlate with malic acid production by natural isolates of Saccharomyces cerevisiae sake strains.

    Science.gov (United States)

    Oba, Takahiro; Kusumoto, Kenichi; Kichise, Yuki; Izumoto, Eiji; Nakayama, Shunichi; Tashiro, Kosuke; Kuhara, Satoru; Kitagaki, Hiroshi

    2014-08-01

    Research on the relationship between mitochondrial membrane potential and fermentation profile is being intensely pursued because of the potential for developing advanced fermentation technologies. In the present study, we isolated naturally occurring strains of yeast from sake mash that produce high levels of malic acid and demonstrate that variations in mitochondrial membrane potential correlate with malic acid production. To define the underlying biochemical mechanism, we determined the activities of enzymes required for malic acid synthesis and found that pyruvate carboxylase and malate dehydrogenase activities in strains that produce high levels of malic acid were elevated compared with the standard sake strain K901. These results inspired us to hypothesize that decreased mitochondrial membrane potential was responsible for increased malic acid synthesis, and we present data supporting this hypothesis. Thus, the mitochondrial membrane potential of high malic acid producers was lower compared with standard strains. We conclude that mitochondrial membrane potential correlates with malic acid production.

  1. Lachancea thermotolerans and Saccharomyces cerevisiae in simultaneous and sequential co-fermentation: a strategy to enhance acidity and improve the overall quality of wine.

    Science.gov (United States)

    Gobbi, Mirko; Comitini, Francesca; Domizio, Paola; Romani, Cristina; Lencioni, Livio; Mannazzu, Ilaria; Ciani, Maurizio

    2013-04-01

    In the last few years there is an increasing interest on the use of mixed fermentation of Saccharomyces and non-Saccharomyces wine yeasts for inoculation of wine fermentations to enhance the quality and improve complexity of wines. In the present work Lachancea (Kluyveromyces) thermotolerans and Saccharomyces cerevisiae were evaluated in simultaneous and sequential fermentation with the aim to enhance acidity and improve the quality of wine. In this specific pairing of yeast strains in mixed fermentations (S. cerevisiae EC1118 and L. thermotolerans 101), this non-Saccharomyces yeast showed a high level of competitiveness. Nevertheless the S. cerevisiae strain dominated the fermentation over the spontaneous S. cerevisiae strains also under the industrial fermentation conditions. The different condition tested (modalities of inoculum, temperature of fermentation, different grape juice) influenced the specific interactions and the fermentation behaviour of the co-culture of S. cerevisiae and L. thermotolerans. However, some metabolic behaviours such as pH reduction and enhancement of 2-phenylethanol and glycerol, were shown here under all of the conditions tested. The specific chemical profiles of these wines were confirmed by the sensory analysis test, which expressed these results at the tasting level as significant increases in the spicy notes and in terms of total acidity increases.

  2. Improvement of acetic acid tolerance of Saccharomyces cerevisiae using a zinc-finger-based artificial transcription factor and identification of novel genes involved in acetic acid tolerance.

    Science.gov (United States)

    Ma, Cui; Wei, Xiaowen; Sun, Cuihuan; Zhang, Fei; Xu, Jianren; Zhao, Xinqing; Bai, Fengwu

    2015-03-01

    Acetic acid is present in cellulosic hydrolysate as a potent inhibitor, and the superior acetic acid tolerance of Saccharomyces cerevisiae ensures good cell viability and efficient ethanol production when cellulosic raw materials are used as substrates. In this study, a mutant strain of S. cerevisiae ATCC4126 (Sc4126-M01) with improved acetic acid tolerance was obtained through screening strains transformed with an artificial zinc finger protein transcription factor (ZFP-TF) library. Further analysis indicated that improved acetic acid tolerance was associated with improved catalase (CAT) activity. The ZFP coding sequence associated with the improved phenotype was identified, and real-time RT-PCR analysis revealed that three of the possible genes involved in the enhanced acetic acid tolerance regulated by this ZFP-TF, namely YFL040W, QDR3, and IKS1, showed decreased transcription levels in Sc4126-M01 in the presence of acetic acid, compared to those in the control strain. Sc4126-M01 mutants having QDR3 and IKS1 deletion (ΔQDR3 and ΔIKS1) exhibited higher acetic acid tolerance than the wild-type strain under acetic acid treatment. Glucose consumption rate and ethanol productivity in the presence of 5 g/L acetic acid were improved in the ΔQDR3 mutant compared to the wild-type strain. Our studies demonstrated that the synthetic ZFP-TF library can be used to improve acetic acid tolerance of S. cerevisiae and that the employment of an artificial transcription factor can facilitate the exploration of novel functional genes involved in stress tolerance of S. cerevisiae.

  3. Metabolic engineering of Pichia pastoris to produce ricinoleic acid, a hydroxy fatty acid of industrial importance.

    Science.gov (United States)

    Meesapyodsuk, Dauenpen; Chen, Yan; Ng, Siew Hon; Chen, Jianan; Qiu, Xiao

    2015-11-01

    Ricinoleic acid (12-hydroxyoctadec-cis-9-enoic acid) has many specialized uses in bioproduct industries, while castor bean is currently the only commercial source for the fatty acid. This report describes metabolic engineering of a microbial system (Pichia pastoris) to produce ricinoleic acid using a "push" (synthesis) and "pull" (assembly) strategy. CpFAH, a fatty acid hydroxylase from Claviceps purpurea, was used for synthesis of ricinoleic acid, and CpDGAT1, a diacylglycerol acyl transferase for the triacylglycerol synthesis from the same species, was used for assembly of the fatty acid. Coexpression of CpFAH and CpDGAT1 produced higher lipid contents and ricinoleic acid levels than expression of CpFAH alone. Coexpression in a mutant haploid strain defective in the Δ12 desaturase activity resulted in a higher level of ricinoleic acid than that in the diploid strain. Intriguingly, the ricinoleic acid produced was mainly distributed in the neutral lipid fractions, particularly the free fatty acid form, but with little in the polar lipids. This work demonstrates the effectiveness of the metabolic engineering strategy and excellent capacity of the microbial system for production of ricinoleic acid as an alternative to plant sources for industrial uses.

  4. KINETIKA FERMENTASI ASAM ASETAT (VINEGAR) OLEH BAKTERI Acetobacter aceti B 127 DARI ETANOL HASIL FERMENTASI LIMBAH CAIR PULP KAKAO [Kinetics of Acetic Acid (Vinegar) Fermentation By Acetobacter aceti B127 from Ethanol Produced by Fermentation of Liquid Waste of Cacao Pulp

    OpenAIRE

    M. Supli Effendi

    2002-01-01

    Acetic acid concentration is one of vinegar’s quality parameter. Acetic acid concentration in vinegar is influenced by the activity of acetic acid bacteria. This research studied the kinetics of anaerobic fermentation of liquid waste of cacao pulp by Saccharomyces cerevisiae R60 to produce ethanol and the kinetics of acetic acid fermentation from ethanol by Acetobacter aceti B127. The kinetics of acetic acid fermentation from ethanol by Acetobacter aceti B127 can be used as a basic of biopro...

  5. Biomass pretreatment affects Ustilago maydis in producing itaconic acid

    Directory of Open Access Journals (Sweden)

    Klement Tobias

    2012-04-01

    Full Text Available Abstract Background In the last years, the biotechnological production of platform chemicals for fuel components has become a major focus of interest. Although ligno-cellulosic material is considered as suitable feedstock, the almost inevitable pretreatment of this recalcitrant material may interfere with the subsequent fermentation steps. In this study, the fungus Ustilago maydis was used to produce itaconic acid as platform chemical for the synthesis of potential biofuels such as 3-methyltetrahydrofuran. No studies, however, have investigated how pretreatment of ligno-cellulosic biomass precisely influences the subsequent fermentation by U. maydis. Thus, this current study aims to first characterize U. maydis in shake flasks and then to evaluate the influence of three exemplary pretreatment methods on the cultivation and itaconic acid production of this fungus. Cellulose enzymatically hydrolysed in seawater and salt-assisted organic-acid catalysed cellulose were investigated as substrates. Lastly, hydrolysed hemicellulose from fractionated beech wood was applied as substrate. Results U. maydis was characterized on shake flask level regarding its itaconic acid production on glucose. Nitrogen limitation was shown to be a crucial condition for the production of itaconic acid. For itaconic acid concentrations above 25 g/L, a significant product inhibition was observed. Performing experiments that simulated influences of possible pretreatment methods, U. maydis was only slightly affected by high osmolarities up to 3.5 osmol/L as well as of 0.1 M oxalic acid. The production of itaconic acid was achieved on pretreated cellulose in seawater and on the hydrolysed hemicellulosic fraction of pretreated beech wood. Conclusion The fungus U. maydis is a promising producer of itaconic acid, since it grows as single cells (yeast-like in submerged cultivations and it is extremely robust in high osmotic media and real seawater. Moreover, U. maydis can grow on

  6. Dietary Saccharomyces cerevisiae Cell Wall Extract Supplementation Alleviates Oxidative Stress and Modulates Serum Amino Acids Profiles in Weaned Piglets

    Science.gov (United States)

    Yu, Lei; Martínez, Yordan

    2017-01-01

    This research aims to evaluate the effects of dietary supplementation with Saccharomyces cerevisiae cell wall extract (SCCWE) on growth performance, oxidative stress, intestinal morphology, and serum amino acid concentration in weaned piglets. Utilizing a completely randomized design, 40 healthy piglets weaned at 21 d were grouped into 4 experimental treatments with 10 pigs per treatment group. Treatments consisted of a basal diet (T0), a basal diet with a 0.05% SCCWE (T1), a basal diet with a 0.10% SCCWE (T2), and a basal diet with a 0.15% SCCWE (T3). SCCWE supplementation increased the average daily gain and final body weight compared with T0 (P < 0.05). SCCWE in T2 and T3 improved the average daily feed intake and decreased the feed/gain ratio compared with T1 and T2 (P < 0.05). SCCWE decreased serum malondialdehyde (MDA) and increased activities of catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD) significantly compared to T0 (P < 0.05). SCCWE increased the concentration of Ile compared to T0 (P < 0.05). Moreover, the concentrations of Leu, Phe, and Arg were higher in T2 and T3 (P < 0.05). These findings indicate beneficial effects of SCCWE supplementation on growth performance, the concentration of some essential amino acids, and alleviation of oxidative stress in weaned piglets.

  7. Multiple GCD genes required for repression of GCN4, a transcriptional activator of amino acid biosynthetic genes in Saccharomyces cerevisiae.

    Science.gov (United States)

    Harashima, S; Hinnebusch, A G

    1986-11-01

    GCN4 encodes a positive regulator of multiple unlinked genes encoding amino acid biosynthetic enzymes in Saccharomyces cerevisiae. Expression of GCN4 is coupled to amino acid availability by a control mechanism involving GCD1 as a negative effector and GCN1, GCN2, and GCN3 as positive effectors of GCN4 expression. We used reversion of a gcn2 gcn3 double mutation to isolate new alleles of GCD1 and mutations in four additional GCD genes which we designate GCD10, GCD11, GCD12, and GCD13. All of the mutations lead to constitutive derepression of HIS4 transcription in the absence of the GCN2+ and GCN3+ alleles. By contrast, the gcd mutations require the wild-type GCN4 allele for their derepressing effect, suggesting that each acts by influencing the level of GCN4 activity in the cell. Consistent with this interpretation, mutations in each GCD gene lead to constitutive derepression of a GCN4::lacZ gene fusion. Thus, at least five gene products are required to maintain the normal repressed level of GCN4 expression in nonstarvation conditions. Interestingly, the gcd mutations are pleiotropic and also affect growth rate in nonstarvation conditions. In addition, certain alleles lead to a loss of M double-stranded RNA required for the killer phenotype. This pleiotropy suggests that the GCD gene products contribute to an essential cellular function, in addition to, or in conjunction with, their role in GCN4 regulation.

  8. Transport and metabolism of fumaric acid in Saccharomyces cerevisiae in aerobic glucose-limited chemostat culture

    NARCIS (Netherlands)

    Shah, Mihir V.; Mastrigt, van Oscar; Heijnen, Joseph J.; Gulik, van Walter M.

    2016-01-01

    Currently, research is being focused on the industrial-scale production of fumaric acid and other relevant organic acids from renewable feedstocks via fermentation, preferably at low pH for better product recovery. However, at low pH a large fraction of the extracellular acid is present in the un

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

    Science.gov (United States)

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

  10. Alternative reactions at the interface of glycolysis and citric acid cycle in Saccharomyces cerevisiae.

    Science.gov (United States)

    van Rossum, Harmen M; Kozak, Barbara U; Niemeijer, Matthijs S; Duine, Hendrik J; Luttik, Marijke A H; Boer, Viktor M; Kötter, Peter; Daran, Jean-Marc G; van Maris, Antonius J A; Pronk, Jack T

    2016-05-01

    Pyruvate and acetyl-coenzyme A, located at the interface between glycolysis and TCA cycle, are important intermediates in yeast metabolism and key precursors for industrially relevant products. Rational engineering of their supply requires knowledge of compensatory reactions that replace predominant pathways when these are inactivated. This study investigates effects of individual and combined mutations that inactivate the mitochondrial pyruvate-dehydrogenase (PDH) complex, extramitochondrial citrate synthase (Cit2) and mitochondrial CoA-transferase (Ach1) in Saccharomyces cerevisiae. Additionally, strains with a constitutively expressed carnitine shuttle were constructed and analyzed. A predominant role of the PDH complex in linking glycolysis and TCA cycle in glucose-grown batch cultures could be functionally replaced by the combined activity of the cytosolic PDH bypass and Cit2. Strongly impaired growth and a high incidence of respiratory deficiency in pda1Δ ach1Δ strains showed that synthesis of intramitochondrial acetyl-CoA as a metabolic precursor requires activity of either the PDH complex or Ach1. Constitutive overexpression of AGP2, HNM1, YAT2, YAT1, CRC1 and CAT2 enabled the carnitine shuttle to efficiently link glycolysis and TCA cycle in l-carnitine-supplemented, glucose-grown batch cultures. Strains in which all known reactions at the glycolysis-TCA cycle interface were inactivated still grew slowly on glucose, indicating additional flexibility at this key metabolic junction.

  11. Organic acid-tolerant microorganisms and uses thereof for producing organic acids

    Science.gov (United States)

    Pfleger, Brian Frederick; Begemann, Matthew Brett

    2014-05-06

    Organic acid-tolerant microorganisms and methods of using same. The organic acid-tolerant microorganisms comprise modifications that reduce or ablate AcsA activity or AcsA homolog activity. The modifications increase tolerance of the microorganisms to such organic acids as 3-hydroxypropionic acid (3HP), acrylic acid, and propionic acid. Further modifications to the microorganisms such as increasing expression of malonyl-CoA reductase and/or acetyl-CoA carboxylase provide or increase the ability of the microorganisms to produce 3HP. Methods of generating an organic acid with the modified microorganisms are provided. Methods of using acsA or homologs thereof as counter-selectable markers include replacing acsA or homologs thereof in cells with genes of interest and selecting for the cells comprising the genes of interest with amounts of organic acids effective to inhibit growth of cells harboring acsA or the homologs.

  12. Improved production of fatty acids by Saccharomyces cerevisiae through screening a cDNA library from the oleaginous yeast Yarrowia lipolytica

    DEFF Research Database (Denmark)

    Shi, Shuobo; Ji, Haichuan; Siewers, Verena;

    2016-01-01

    for screening a cDNA library from the oleaginous yeast Yarrowia lipolytica for identification of genes/enzymes that were able to enhance free FA accumulation in Saccharomyces cerevisiae. Several novel enzymes resulting in increasing FA accumulation were discovered. These targets include a GPI anchor protein...... method for high-throughput evaluation of the content of free FAs, but also give new insight into how enzymes from Y. lipolytica may increase the production of fatty acids in S. cerevisiae....

  13. The fraction of cells that resume growth after acetic acid addition is a strain-dependent parameter of acetic acid tolerance in Saccharomyces cerevisiae.

    Science.gov (United States)

    Swinnen, Steve; Fernández-Niño, Miguel; González-Ramos, Daniel; van Maris, Antonius J A; Nevoigt, Elke

    2014-06-01

    High acetic acid tolerance of Saccharomyces cerevisiae is a relevant phenotype in industrial biotechnology when using lignocellulosic hydrolysates as feedstock. A screening of 38 S. cerevisiae strains for tolerance to acetic acid revealed considerable differences, particularly with regard to the duration of the latency phase. To understand how this phenotype is quantitatively manifested, four strains exhibiting significant differences were studied in more detail. Our data show that the duration of the latency phase is primarily determined by the fraction of cells within the population that resume growth. Only this fraction contributed to the exponential growth observed after the latency phase, while all other cells persisted in a viable but non-proliferating state. A remarkable variation in the size of the fraction was observed among the tested strains differing by several orders of magnitude. In fact, only 11 out of 10(7)  cells of the industrial bioethanol production strain Ethanol Red resumed growth after exposure to 157 mM acetic acid at pH 4.5, while this fraction was 3.6 × 10(6) (out of 10(7)  cells) in the highly acetic acid tolerant isolate ATCC 96581. These strain-specific differences are genetically determined and represent a valuable starting point to identify genetic targets for future strain improvement.

  14. Antimicrobial peptides (AMPs) produced by Saccharomyces cerevisiae induce alterations in the intracellular pH, membrane permeability and culturability of Hanseniaspora guilliermondii cells

    DEFF Research Database (Denmark)

    Branco, Patrícia; Monteiro Lomba Viana, Tiago; Albergaria, Helena

    2015-01-01

    Saccharomyces cerevisiae produces antimicrobial peptides (AMPs) during alcoholic fermentation that are active against several wine-related yeasts (e.g. Hanseniaspora guilliermondii) and bacteria (e.g. Oenococcus oeni). In the present study, the physiological changes induced by those AMPs...

  15. Transport and metabolic effects of alpha-aminoisobutyric acid in Saccharomyces cerevisiae.

    Science.gov (United States)

    Kim, K W; Roon, R J

    1982-11-24

    alpha-Aminoisobutyric acid is actively transported into yeast cells by the general amino acid transport system. The system exhibits a Km for alpha-aminoisobutyric acid of 270 microM, a Vmax of 24 nmol/min per mg cells (dry weight), and a pH optimum of 4.1-4.3. alpha-Aminoisobutyric acid is also transported by a minor system(s) with a Vmax of 1.7 nmol/min per mg cells. Transport occurs against a concentration gradient with the concentration ratio reaching over 1000:1 (in/out). The alpha-aminoisobutyric acid is not significantly metabolized or incorporated into protein after an 18 h incubation. alpha-Aminoisobutyric acid inhibits cell growth when a poor nitrogen source such as proline is provided but not with good nitrogen sources such as NH+4. During nitrogen starvation alpha-aminoisobutyric acid strongly inhibits the synthesis of the nitrogen catabolite repression sensitive enzyme, asparaginase II. Studies with a mutant yeast strain (GDH-CR) suggest that alpha-aminoisobutyric acid inhibition of asparaginase II synthesis occurs because alpha-aminoisobutyric acid is an effective inhibitor of protein synthesis in nitrogen starved cells.

  16. Harnessing biodiesel-producing microbes: from genetic engineering of lipase to metabolic engineering of fatty acid biosynthetic pathway.

    Science.gov (United States)

    Yan, Jinyong; Yan, Yunjun; Madzak, Catherine; Han, Bingnan

    2017-02-01

    Microbial production routes, notably whole-cell lipase-mediated biotransformation and fatty-acids-derived biosynthesis, offer new opportunities for synthesizing biodiesel. They compare favorably to immobilized lipase and chemically catalyzed processes. Genetically modified whole-cell lipase-mediated in vitro route, together with in vivo and ex vivo microbial biosynthesis routes, constitutes emerging and rapidly developing research areas for effective production of biodiesel. This review presents recent advances in customizing microorganisms for producing biodiesel, via genetic engineering of lipases and metabolic engineering (including system regulation) of fatty-acids-derived pathways. Microbial hosts used include Escherichia coli, Saccharomyces cerevisiae, Pichia pastoris and Aspergillus oryzae. These microbial cells can be genetically modified to produce lipases under different forms: intracellularly expressed, secreted or surface-displayed. They can be metabolically redesigned and systematically regulated to obtain balanced biodiesel-producing cells, as highlighted in this study. Such genetically or metabolically modified microbial cells can support not only in vitro biotransformation of various common oil feedstocks to biodiesel, but also de novo biosynthesis of biodiesel from glucose, glycerol or even cellulosic biomass. We believe that the genetically tractable oleaginous yeast Yarrowia lipolytica could be developed to an effective biodiesel-producing microbial cell factory. For this purpose, we propose several engineered pathways, based on lipase and wax ester synthase, in this promising oleaginous host.

  17. Methods of refining and producing isomerized fatty acid esters and fatty acids from natural oil feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Snead, Thomas E.; Cohen, Steven A.; Gildon, Demond L.; Beltran, Leslie V.; Kunz, Linda A.; Pals, Tessa M.; Quinn, Jordan R; Behrends, Jr., Raymond T.; Bernhardt, Randal J.

    2016-07-05

    Methods are provided for refining natural oil feedstocks and producing isomerized esters and acids. The methods comprise providing a C4-C18 unsaturated fatty ester or acid, and isomerizing the fatty acid ester or acid in the presence of heat or an isomerization catalyst to form an isomerized fatty ester or acid. In some embodiments, the methods comprise forming a dibasic ester or dibasic acid prior to the isomerizing step. In certain embodiments, the methods further comprise hydrolyzing the dibasic ester to form a dibasic acid. In certain embodiments, the olefin is formed by reacting the feedstock in the presence of a metathesis catalyst under conditions sufficient to form a metathesized product comprising olefins and esters, separating the olefins from the esters in the metathesized product, and transesterifying the esters in the presence of an alcohol to form a transesterified product having unsaturated esters.

  18. Electrochemical evaluation of the inhibitory effects of acetic acid on Saccharomyces cerevisiae

    Institute of Scientific and Technical Information of China (English)

    Yuan Zhenhong; Zhao Jinsheng; Yan Yongjie; Yang Zhengyu

    2006-01-01

    A mediated electrochemical method was proposed for toxic evaluation of acetic acid on S. cerevisiae AS.380, and menadione/ferricyanide was chosen as the mediator system. The variance in electrochemical response in the absence and presence of increasing concentrations of acetic acid were used to indicate the inhibitory effects of weak acid on the yeast. The inhibitory effects of acetic acid on glucose consumption during menadione mediated reduction of ferricyanide were also measured for comparison purpose. The relative limiting current and the glucose consumption were reduced by 64.5 % and 61%, respectively, in the presence of 4g/L acetic acid at pH 4.0. The results showed that the electrochemical method can provide us with an appropriate and convenient tool for cytotoxic evaluation.

  19. Selective recovery of copper, nickel and zinc from ashes produced from Saccharomyces cerevisiae contaminated biomass used in the treatment of real electroplating effluents.

    Science.gov (United States)

    Machado, Manuela D; Soares, Eduardo V; Soares, Helena M V M

    2010-12-15

    The aim of this work was to seek an environmentally friendly process for recycling metals from biomass-sludges generated in the treatment of industrial wastewaters. This work proposes a hybrid process for selective recovery of copper, nickel and zinc from contaminated biomass of Saccharomyces cerevisiae, used in the bioremediation of electroplating effluents. The developed separation scheme comprised five consecutive steps: (1) incineration of the contaminated biomass; (2) microwave acid (HCl) digestion of the ashes; (3) recovery of copper from the acid solution by electrolysis at controlled potential; (4) recycle of nickel, as nickel hydroxide, by alcalinization of the previous solution at pH 14; (5) recovery of zinc, as zinc hydroxide, by adjusting the pH of the previous solution at 10. This integrated approach allowed recovering each metal with high yielder (>99% for all metals) and purity (99.9%, 92% and 99.4% for copper, nickel and zinc, respectively). The purity of the metals recovered allows selling them in the market or being recycled in the electroplating process without waste generation.

  20. Characterization of fatty acid delta-6 desaturase gene in Nile tilapia and heterogenous expression in Saccharomyces cerevisiae.

    Science.gov (United States)

    Tanomman, Supamas; Ketudat-Cairns, Mariena; Jangprai, Araya; Boonanuntanasarn, Surintorn

    2013-10-01

    Fatty acid delta-6 desaturase (fads2)-like gene from Nile tilapia (Oreochromis niloticus) was characterized and designated as oni-fads2. The Oni-FADS2 showed the typical structure of microsomal FADS2. The presence of oni-fads2 transcripts in unfertilized eggs demonstrated the maternal role of Nile tilapia in providing the oni-fads2 transcript in their eggs. In addition, the expression of oni-fads2 was detectable in embryos throughout the hatching stage. Real-time reverse transcription-PCR revealed that oni-fads2 was expressed at a high level in all the brain regions, liver, and testis. Recombinant yeast (RY) was generated by transformation of Saccharomyces cerevisiae with the plasmid containing oni-fads2 driven by the Gal1 promoter (pYoni-fads2). The conspicuous expression of RY was detectable by RT-PCR after induction with galactose for 24h. When RY was induced with galactose, it exhibited 39% and 7% of delta-6 desaturase (∆6) activity toward C18:2n6 and C18:3n3, respectively. Additionally, it displayed 4% of delta-5 desaturase (∆5) activity toward C20:3n6, indicating that Oni-FADS2 had ∆5 and ∆6 bifunction.

  1. Cell membrane fatty acid changes and desaturase expression of Saccharomyces bayanus exposed to high pressure homogenization in relation to the supplementation of exogenous unsaturated fatty acids

    Science.gov (United States)

    Serrazanetti, Diana I.; Patrignani, Francesca; Russo, Alessandra; Vannini, Lucia; Siroli, Lorenzo; Gardini, Fausto; Lanciotti, Rosalba

    2015-01-01

    Aims: The aim of this work was to study the responses of Saccharomyces bayanus cells exposed to sub-lethal high-pressure homogenization (HPH) and determine whether the plasmatic membrane can sense HPH in the presence, or absence, of exogenous unsaturated fatty acids (UFAs) in the growth medium. Methods and Results: High-pressure homogenization damaged and caused the collapse of cell walls and membranes of a portion of cells; however, HPH did not significantly affect S. bayanus cell viability (less than 0.3 Log CFU ml-1). HPH strongly affected the membrane fatty acid (FA) composition by increasing the percentage of total UFA when compared with saturated fatty acids. The gene expression showed that the transcription of OLE1, ERG3, and ERG11 increased after HPH. The presence of exogenous UFA abolished HPH-induced effects on the OLE1 and ERG3 genes, increased the percentage of membrane lipids and decreased the expression of OLE1 and ERG3 within 30 min of treatment. Conclusion: The results suggest a key role for UFA in the microbial cell response to sub-lethal stress. In addition, these data provide insight into the molecular basis of the response of S. bayanus to this innovative technology. Significance and Impact of the Study: Elucidation of the mechanism of action for sub-lethal HPH will enable the utilization of this technology to modulate the starter performance at the industrial scale. PMID:26528258

  2. Point mutation of H3/H4 histones affects acetic acid tolerance in Saccharomyces cerevisiae.

    Science.gov (United States)

    Liu, Xiangyong; Zhang, Xiaohua; Zhang, Zhaojie

    2014-10-10

    The molecular mechanism of acetic acid tolerance in yeast remains unclear despite of its importance for efficient cellulosic ethanol production. In this study, we examined the effects of histone H3/H4 point mutations on yeast acetic acid tolerance by comprehensively screening a histone H3/H4 mutant library. A total of 24 histone H3/H4 mutants (six acetic acid resistant and 18 sensitive) were identified. Compared to the wild-type strain, the histone acetic acid-resistant mutants exhibited improved ethanol fermentation performance under acetic acid stress. Genome-wide transcriptome analysis revealed that changes in the gene expression in the acetic acid-resistant mutants H3 K37A and H4 K16Q were mainly related to energy production, antioxidative stress. Our results provide novel insights into yeast acetic acid tolerance on the basis of histone, and suggest a novel approach to improve ethanol production by altering the histone H3/H4 sequences.

  3. Bacteriocins produced by lactic acid bacteria: A review

    Directory of Open Access Journals (Sweden)

    Vesković-Moračanin Slavica M.

    2014-01-01

    Full Text Available Lactic acid bacteria (LAB have an essential role in the production of fermented products. With their metabolic activity, they influence the ripening processes - leading to desired sensory qualities while at the same time inhibiting the growth of undesired microorganisms. Because of their dominant role during fermentation and because of a long tradition of utilization, Lhave been designated as “safe microbiota”. Biological protection of LAB, as a naturally present and/or selected and intentionally added microflora, is realized through the production of non-specific (lactic acid, acetic acid and other volatile organic acids, hydrogen peroxide, diacetyl, etc and specific metabolites, bacteriocins. Bacteriocins are extracellularly released proteins or peptides which possess certain antibacterial activity towards certain types of microorganisms, usually related to the producing bacteria. Today, bacteriocins represent a very interesting potential for their application in the food industry. Their application can reduce the use of synthetic preservatives and/or the intensity of thermal treatment during food production consumer’s need for safe, fresh and minimally-processed food. With the intention of realizing this potential to the fullest, it is necessary to understand the nature of bacteriocins, their production mechanisms, regulations and actions, as well as the influence of external factors on the their antimicrobial activity. The composition of food, i.e. its characteristics (pH, temperature, ingredients and additives, types and quantities of epiphytic microbiota and the actual technological process used in production, can all influence the stability and activity of the added bacteriocins. The future research in this field should also aim to clarify this unknown aspect of the application of bacteriocins, to provide the necessary knowledge about the optimization of the external conditions and open up the possibility of discovering their new

  4. Biologically produced succinic acid: A new route to chemical intermediates

    Energy Technology Data Exchange (ETDEWEB)

    1995-01-01

    The US Department of Energy (DOE) Alternative Feedstocks (AF) program is forging new links between the agricultural community and the chemicals industry through support of research and development (R & D) that uses `green` feedstocks to produce chemicals. The program promotes cost-effective industrial use of renewable biomass as feedstocks to manufacture high-volume chemical building blocks. Industrial commercialization of such processes would stimulate the agricultural sector by increasing the demand of agricultural and forestry commodities. New alternatives for American industry may lie in the nation`s forests and fields. The national laboratory consortium has undertaken a joint R&D project with the Michigan Biotechnology Institute to demonstrate the feasibility of producing a chemical intermediate, succinic acid, and various derivatives, from renewable agricultural resources.

  5. Global mapping of protein phosphorylation events identifies Ste20, Sch9 and the cell-cycle regulatory kinases Cdc28/Pho85 as mediators of fatty acid starvation responses in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Pultz, Dennis; Bennetzen, Martin V; Rødkær, Steven Vestergaard;

    2012-01-01

    Synthesis, degradation, and metabolism of fatty acids are strictly coordinated to meet the nutritional and energetic needs of cells and organisms. In the absence of exogenous fatty acids, proliferation and growth of the yeast Saccharomyces cerevisiae depends on endogenous synthesis of fatty acids...

  6. Short-term adaptation improves the fermentation performance of Saccharomyces cerevisiae in the presence of acetic acid at low pH

    OpenAIRE

    Sànchez i Nogué, Violeta; Narayanan, Venkatachalam; Gorwa-Grauslund, Marie F

    2013-01-01

    The release of acetic acid due to deacetylation of the hemicellulose fraction during the treatment of lignocellulosic biomass contributes to the inhibitory character of the generated hydrolysates. In the present study, we identified a strain-independent adaptation protocol consisting of pre-cultivating the strain at pH 5.0 in the presence of at least 4 g L−1 acetic acid that enabled aerobic growth and improved fermentation performance of Saccharomyces cerevisiae cells at low pH (3.7) and in t...

  7. Saccharomyces boulardii

    Science.gov (United States)

    ... bowel syndrome. Some people use Saccharomyces boulardii for lactose intolerance, urinary tract infections (UTIs), vaginal yeast infections, high ... cholesterol. Lyme disease. Hives. Fever blisters. Canker sores. Lactose intolerance. Other conditions. More evidence is needed to rate ...

  8. Fatty acid-derived biofuels and chemicals production in Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Yongjin J. Zhou

    2014-09-01

    Full Text Available Volatile energy costs and environmental concerns have spurred interest in the development of alternative, renewable, sustainable and cost-effective energy resources. Advanced biofuels have potential to replace fossil fuels in supporting high-power demanding machinery such as aircrafts and trucks. Microbial biosynthesis is generally considered as an environmental friendly refinery process, and fatty acid biosynthesis is an attractive route to synthesize chemicals and especially drop-in biofuels due to the high degree of reduction of fatty acids. The robustness and excellent accessibility to molecular genetics make the yeast S. cerevisiae a suitable host for the production of biofuels, chemicals and pharmaceuticals, and recent advances in metabolic engineering as well as systems and synthetic biology allow us to engineer the yeast fatty acid metabolism and modification pathways for production of advanced biofuels and chemicals.

  9. Hyper- and hyporesponsive mutant forms of the Saccharomyces cerevisiae Ssy1 amino acid sensor

    DEFF Research Database (Denmark)

    Poulsen, Peter; Gaber, Richard F.; Kielland-Brandt, Morten

    2008-01-01

    T639I) turned out to be hyporesponsive, i.e., it signals only at high inducer concentration. In accordance with a transporter-like mechanism for Ssy1p function we suggest that the hyper- and hyporesponsive mutant forms differ from the wild-type sensor by being more and less inclined, respectively...... related to amino acid permeases, but unable to transport amino acids. We isolated SSY1 mutants that constitutively activate a target promoter. Dose-response analysis showed that the mutants are hyperresponsive, requiring less inducer to give strong signaling than does the wild type. Another mutant (Ssy1p......, to adopt an outward-facing, signaling conformation. Coordinate conformational dynamics of the sensor complex was supported by additive effects of combinations of constitutive SSY1, PTR3 and SSY5 alleles. Assuming structural similarity of Ssy1p to the distantly related bacterial leucine transporter Leu...

  10. Isolation, identification and optimization of ethanol producing bacteria from Saccharomyces-based fermentation process of alcohol industries in Iran

    Directory of Open Access Journals (Sweden)

    Hoda Ebrahimi

    2013-01-01

    Full Text Available Introduction: Due to the vast growth of world population, consumption of a lot of energy, limited energy supply and rising prices of fuel oil in the future, other alternative energy source is essential. Ethanol is renewable and a safe fuel and it is mainly based on microbial fermentation. The purpose of this study was isolation of high ethanol producing bacteria from the fermentation process of alcohol industries and optimization of growth conditions to be introduced to the industries. Materials and methods: The samples that were collected from fermentation tanks of alcohol industries were enriched in ZSM medium. To isolate the ethanol producing bacteria, the enriched culture was transferred on RMA agar. Bacterial growth conditions and their effects on ethanol production were optimized based on pH, growth temperature, agitation, fermentation time, initial substrate concentration and carbon and nitrogen sources. In addition, the morphological, physiological and molecular characterizations were investigated for identification of the isolates.Results: Three bacterial isolates ZYM7, ZYM8 and ZYM9 were isolated from fermentation tank. All isolates were able to produce ethanol 5.00, 7.60 and 4.00 gL-1 after 48 hours, respectively. The results demonstrated that all isolates were able to consume most sugars sources specially pentose carbon xylose. The isolate ZYM7 produced 13.00 gL-1 ethanol by consumption of xylose. The results of morphological and physiological characteristics showed that ZYM7 belonged to Lactobacillus sp. and ZYM8 and ZYM9 belonged to Acetobacter sp. Moreover, 16S rRNA sequencing and phylogenetic analyses exhibited that ZYM7 was similar to Lactobacillus rhamnosus with 99% homology and ZYM8 and ZYM9 were similar to Acetobacter pasteurianus with 99 and 98% homology, respectively.Discussion and conclusion: The results showed that that the isolated bacteria were suitable candidates to produce ethanol from raw material enriched with

  11. Isolation, identification and optimization of ethanol producing bacteria from Saccharomyces-based fermentation process of alcohol industries in Iran

    OpenAIRE

    Hoda Ebrahimi; Mojtaba Mohseni

    2013-01-01

    Introduction: Due to the vast growth of world population, consumption of a lot of energy, limited energy supply and rising prices of fuel oil in the future, other alternative energy source is essential. Ethanol is renewable and a safe fuel and it is mainly based on microbial fermentation. The purpose of this study was isolation of high ethanol producing bacteria from the fermentation process of alcohol industries and optimization of growth conditions to be introduced to the industries. Materi...

  12. Metabolic engineering of Saccharomyces cerevisiae for production of eicosapentaenoic acid, using a novel δ5-desaturase from Paramecium tetraurelia

    DEFF Research Database (Denmark)

    de Andrade Pereira Tavares, Sabina; Grotkjær, Thomas; Obsen, Thomas;

    2011-01-01

    protozoan Paramecium tetraurelia and from the microalgae Ostreococcus tauri and Ostreococcus lucimarinus were identified via a BLAST search, and their substrate preferences and desaturation efficiencies were assayed in a yeast strain producing the ω6 and ω3 fatty acid substrates for Δ5-desaturation. The Δ5...

  13. Changes of cellular fatty acids of soil Actinobacteria producing antibiotics

    OpenAIRE

    LIPENSKÁ, Ivana

    2010-01-01

    Changes of cellular fatty acids in membrane of Actinobacteria. Changes of fatty acids are significant biomarkers of changing conditions of surroundings. This can also indicate production of antibiotics along with production of atypical fatty acids.

  14. New insights into {gamma}-aminobutyric acid catabolism: Evidence for {gamma}-hydroxybutyric acid and polyhydroxybutyrate synthesis in Saccharomyces cerevisiae.

    Science.gov (United States)

    Bach, Benoît; Meudec, Emmanuelle; Lepoutre, Jean-Paul; Rossignol, Tristan; Blondin, Bruno; Dequin, Sylvie; Camarasa, Carole

    2009-07-01

    The gamma-aminobutyrate (GABA) shunt, an alternative route for the conversion of alpha-ketoglutarate to succinate, involves the glutamate decarboxylase Gad1p, the GABA transaminase Uga1p and the succinate semialdehyde dehydrogenase Uga2p. This pathway has been extensively described in plants and animals, but its function in yeast remains unclear. We show that the flux through Gad1p is insignificant during fermentation in rich sugar-containing medium, excluding a role for this pathway in redox homeostasis under anaerobic conditions or sugar stress. However, we found that up to 4 g of exogenous GABA/liter was efficiently consumed by yeast. We studied the fate of this consumed GABA. Most was converted into succinate, with a reaction yield of 0.7 mol/mol. We also showed that a large proportion of GABA was stored within cells, indicating a possible role for this molecule in stress tolerance mechanisms or nitrogen storage. Furthermore, based on enzymatic and metabolic evidence, we identified an alternative route for GABA catabolism, involving the reduction of succinate-semialdehyde into gamma-hydroxybutyric acid and the polymerization of gamma-hydroxybutyric acid to form poly-(3-hydroxybutyric acid-co-4-hydroxybutyric acid). This study provides the first demonstration of a native route for the formation of this polymer in yeast. Our findings shed new light on the GABA pathway and open up new opportunities for industrial applications.

  15. Metabolic engineering of Saccharomyces cerevisiae for optimizing 3HP production

    DEFF Research Database (Denmark)

    Jensen, Niels Bjerg; Maury, Jerome; Oberg, Fredrik;

    2012-01-01

    and the market for acrylate products exceeds USD 100 billion. As an alternative to oil and gas derived acrylic acid, 3-hydroxypropionic (3HP) acid produced from renewable sources is highly desired, because 3HP can easily be converted into acrylic acid. We are setting out to produce 3HP in yeast Saccharomyces...... cerevisiae. One main reason for selecting Baker's yeast as host organism is that yeast has a high tolerance towards low pH in comparison to bacteria, e.g. E. coli. Hence, it lowers the consumption of base for neutralization of growth media when compared to bacteria. The preferred engineered pathway towards 3...

  16. Oleanolic acid alters bile acid metabolism and produces cholestatic liver injury in mice

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie, E-mail: JLiu@kumc.edu [University of Kansas Medical Center, Kansas City, KS 66160 (United States); Zunyi Medical College, Zunyi 563003 (China); Lu, Yuan-Fu [University of Kansas Medical Center, Kansas City, KS 66160 (United States); Zunyi Medical College, Zunyi 563003 (China); Zhang, Youcai; Wu, Kai Connie [University of Kansas Medical Center, Kansas City, KS 66160 (United States); Fan, Fang [Cytopathology, University of Kansas Medical Center, Kansas City, KS 66160 (United States); Klaassen, Curtis D. [University of Kansas Medical Center, Kansas City, KS 66160 (United States)

    2013-11-01

    Oleanolic acid (OA) is a triterpenoids that exists widely in plants. OA is effective in protecting against hepatotoxicants. Whereas a low dose of OA is hepatoprotective, higher doses and longer-term use of OA produce liver injury. This study characterized OA-induced liver injury in mice. Adult C57BL/6 mice were given OA at doses of 0, 22.5, 45, 90, and 135 mg/kg, s.c., daily for 5 days, and liver injury was observed at doses of 90 mg/kg and above, as evidenced by increases in serum activities of alanine aminotransferase and alkaline phosphatase, increases in serum total bilirubin, as well as by liver histopathology. OA-induced cholestatic liver injury was further evidenced by marked increases of both unconjugated and conjugated bile acids (BAs) in serum. Gene and protein expression analysis suggested that livers of OA-treated mice had adaptive responses to prevent BA accumulation by suppressing BA biosynthetic enzyme genes (Cyp7a1, 8b1, 27a1, and 7b1); lowering BA uptake transporters (Ntcp and Oatp1b2); and increasing a BA efflux transporter (Ostβ). OA increased the expression of Nrf2 and its target gene, Nqo1, but decreased the expression of AhR, CAR and PPARα along with their target genes, Cyp1a2, Cyp2b10 and Cyp4a10. OA had minimal effects on PXR and Cyp3a11. Taken together, the present study characterized OA-induced liver injury, which is associated with altered BA homeostasis, and alerts its toxicity potential. - Highlights: • Oleanolic acid at higher doses and long-term use may produce liver injury. • Oleanolic acid increased serum ALT, ALP, bilirubin and bile acid concentrations. • OA produced feathery degeneration, inflammation and cell death in the liver. • OA altered bile acid homeostasis, affecting bile acid synthesis and transport.

  17. Ethanol at levels produced by Saccharomyces cerevisiae during wheat dough fermentation has a strong impact on dough properties.

    Science.gov (United States)

    Jayaram, Vinay B; Rezaei, Mohammad N; Cuyvers, Sven; Verstrepen, Kevin J; Delcour, Jan A; Courtin, Christophe M

    2014-09-24

    Yeast's role in bread making is primarily the fermentative production of carbon dioxide to leaven the dough. Fermentation also impacts dough matrix rheology, thereby affecting the quality of the end product. Surprisingly, the role of ethanol, the other yeast primary metabolite, has been ill studied in this context. Therefore, this study aims to assess the potential impact of ethanol on yeastless dough extensibility and spread and gluten agglomeration at concentrations at which it is produced in fermenting dough, i.e., up to 60 mmol per 100 g of flour. Reduced dough extensibility and dough spread were observed upon incorporation of ethanol in the dough formula, and were more pronounced for a weak than for a strong flour. Uniaxial and biaxial extension tests showed up to 50% decrease in dough extensibility and a dough strength increase of up to 18% for 60 mmol of ethanol/100 g of flour. Ethanol enhanced gluten agglomeration of a weak flour. Sequential extraction of flour in increasing ethanol concentrations showed that better gluten-solvent interaction is a possible explanation for the changed dough behavior.

  18. Impact of oxygenation on the performance of three non-Saccharomyces yeasts in co-fermentation with Saccharomyces cerevisiae.

    Science.gov (United States)

    Shekhawat, Kirti; Bauer, Florian F; Setati, Mathabatha E

    2017-03-01

    The sequential or co-inoculation of grape must with non-Saccharomyces yeast species and Saccharomyces cerevisiae wine yeast strains has recently become a common practice in winemaking. The procedure intends to enhance unique aroma and flavor profiles of wine. The extent of the impact of non-Saccharomyces strains depends on their ability to produce biomass and to remain metabolically active for a sufficiently long period. However, mixed-culture wine fermentations tend to become rapidly dominated by S. cerevisiae, reducing or eliminating the non-Saccharomyces yeast contribution. For an efficient application of these yeasts, it is therefore essential to understand the environmental factors that modulate the population dynamics of such ecosystems. Several environmental parameters have been shown to influence population dynamics, but their specific effect remains largely uncharacterized. In this study, the population dynamics in co-fermentations of S. cerevisiae and three non-Saccharomyces yeast species: Torulaspora delbrueckii, Lachancea thermotolerans, and Metschnikowia pulcherrima, was investigated as a function of oxygen availability. In all cases, oxygen availability strongly influenced population dynamics, but clear species-dependent differences were observed. Our data show that L. thermotolerans required the least oxygen, followed by T. delbrueckii and M. pulcherrima. Distinct species-specific chemical volatile profiles correlated in all cases with increased persistence of non-Saccharomyces yeasts, in particular increases in some higher alcohols and medium chain fatty acids. The results highlight the role of oxygen in regulating the succession of yeasts during wine fermentations and suggests that more stringent aeration strategies would be necessary to support the persistence of non-Saccharomyces yeasts in real must fermentations.

  19. Oxalic acid production by citric acid-producing Aspergillus niger overexpressing the oxaloacetate hydrolase gene oahA.

    Science.gov (United States)

    Kobayashi, Keiichi; Hattori, Takasumi; Honda, Yuki; Kirimura, Kohtaro

    2014-05-01

    The filamentous fungus Aspergillus niger is used worldwide in the industrial production of citric acid. However, under specific cultivation conditions, citric acid-producing strains of A. niger accumulate oxalic acid as a by-product. Oxalic acid is used as a chelator, detergent, or tanning agent. Here, we sought to develop oxalic acid hyperproducers using A. niger as a host. To generate oxalic acid hyperproducers by metabolic engineering, transformants overexpressing the oahA gene, encoding oxaloacetate hydrolase (OAH; EC 3.7.1.1), were constructed in citric acid-producing A. niger WU-2223L as a host. The oxalic acid production capacity of this strain was examined by cultivation of EOAH-1 under conditions appropriate for oxalic acid production with 30 g/l glucose as a carbon source. Under all the cultivation conditions tested, the amount of oxalic acid produced by EOAH-1, a representative oahA-overexpressing transformant, exceeded that produced by A. niger WU-2223L. A. niger WU-2223L and EOAH-1 produced 15.6 and 28.9 g/l oxalic acid, respectively, during the 12-day cultivation period. The yield of oxalic acid for EOAH-1 was 64.2 % of the maximum theoretical yield. Our method for oxalic acid production gave the highest yield of any study reported to date. Therefore, we succeeded in generating oxalic acid hyperproducers by overexpressing a single gene, i.e., oahA, in citric acid-producing A. niger as a host.

  20. Short-term adaptation improves the fermentation performance of Saccharomyces cerevisiae in the presence of acetic acid at low pH.

    Science.gov (United States)

    Sànchez i Nogué, Violeta; Narayanan, Venkatachalam; Gorwa-Grauslund, Marie F

    2013-08-01

    The release of acetic acid due to deacetylation of the hemicellulose fraction during the treatment of lignocellulosic biomass contributes to the inhibitory character of the generated hydrolysates. In the present study, we identified a strain-independent adaptation protocol consisting of pre-cultivating the strain at pH 5.0 in the presence of at least 4 g L⁻¹ acetic acid that enabled aerobic growth and improved fermentation performance of Saccharomyces cerevisiae cells at low pH (3.7) and in the presence of inhibitory levels of acetic acid (6 g L⁻¹). During anaerobic cultivation with adapted cells of strain TMB3500, the specific ethanol production rate was increased, reducing the fermentation time to 48 %.

  1. Vectorial acylation in Saccharomyces cerevisiae. Fat1p and fatty acyl-CoA synthetase are interacting components of a fatty acid import complex

    DEFF Research Database (Denmark)

    Zou, Zhiying; Tong, Fumin; Færgeman, Nils J.

    2003-01-01

    In Saccharomyces cerevisiae Fat1p and fatty acyl-CoA synthetase (FACS) are hypothesized to couple import and activation of exogenous fatty acids by a process called vectorial acylation. Molecular genetic and biochemical studies were used to define further the functional and physical interactions...... and Fat1p play distinct roles in the fatty acid import process. When expressed from a 2-mu plasmid, Fat1p contributes significant oleoyl-CoA synthetase activity, which indicates vectorial esterification and metabolic trapping are the driving forces behind import. Evidence of a physical interaction between...... as trap were active when tested using the yeast two-hybrid system. Third, co-expressed, differentially tagged Fat1p and Faa1p or Faa4p were co-immunoprecipitated. Collectively, these data support the hypothesis that fatty acid import by vectorial acylation in yeast requires a multiprotein complex, which...

  2. Method of producing an oil including docosahexaenoic acid

    NARCIS (Netherlands)

    Ratledge, C.; Anderson, A.J.; Kanagachandran, K.; Grantham, D.J.; Stephenson, J.C.; Swaaf, de M.E.; Sijtsma, L.

    2005-01-01

    C. cohnii is cultured in a suitable growth medium with acetic acid/acetate as the main carbon source. The acetate is provided, and replenished, by adding acetic acid to the growth medium in response to an increase in pH resulting from the utilisation of acetic acid/acetate by C. cohnii. The C. cohni

  3. Mapping of Saccharomyces cerevisiae metabolites in fermenting wheat straight-dough reveals succinic acid as pH-determining factor.

    Science.gov (United States)

    Jayaram, Vinay B; Cuyvers, Sven; Lagrain, Bert; Verstrepen, Kevin J; Delcour, Jan A; Courtin, Christophe M

    2013-01-15

    Fermenting yeast does not merely cause dough leavening, but also contributes to the bread aroma and might alter dough rheology. Here, the yeast carbon metabolism was mapped during bread straight-dough fermentation. The concentration of most metabolites changed quasi linearly as a function of fermentation time. Ethanol and carbon dioxide concentrations reached up to 60 mmol/100g flour. Interestingly, high levels of glycerol (up to 10 mmol/100g flour) and succinic acid (up to 1.6 mmol/100g flour) were produced during dough fermentation. Further tests showed that, contrary to current belief, the pH decrease in fermenting dough is primarily caused by the production of succinic acid by the yeast instead of carbon dioxide dissolution or bacterial organic acids. Together, our results provide a comprehensive overview of metabolite production during dough fermentation and yield insight into the importance of some of these metabolites for dough properties.

  4. Characterization of a recombinant flocculent Saccharomyces cerevisiae strain that co-ferments glucose and xylose: II. influence of pH and acetic acid on ethanol production.

    Science.gov (United States)

    Matsushika, Akinori; Sawayama, Shigeki

    2012-12-01

    The inhibitory effects of pH and acetic acid on the co-fermentation of glucose and xylose in complex medium by recombinant flocculent Saccharomyces cerevisiae MA-R4 were evaluated. In the absence of acetic acid, the fermentation performance of strain MA-R4 was similar between pH 4.0-6.0, but was negatively affected at pH 2.5. The addition of acetic acid to batch cultures resulted in negligible inhibition of several fermentation parameters at pH 6.0, whereas the interactive inhibition of pH and acetic acid on the maximum cell and ethanol concentrations, and rates of sugar consumption and ethanol production were observed at pH levels below 5.4. The inhibitory effect of acetic acid was particularly marked for the consumption rate of xylose, as compared with that of glucose. With increasing initial acetic acid concentration, the ethanol yield slightly increased at pH 5.4 and 6.0, but decreased at pH values lower than 4.7. Notably, ethanol production was nearly completely inhibited under low pH (4.0) and high acetic acid (150-200 mM) conditions. Together, these results indicate that the inhibitory effects of acetic acid and pH on ethanol fermentation by MA-R4 are highly synergistic, although the inhibition can be reduced by increasing the medium pH.

  5. Cloning and functional analysis of putative malonyl-CoA:acyl-carrier protein transacylase gene from the docosahexaenoic acid-producer Schizochytrium sp. TIO1101.

    Science.gov (United States)

    Cheng, Rubin; Ge, Yuqing; Yang, Bo; Zhong, Xiaoming; Lin, Xiangzhi; Huang, Zhen

    2013-06-01

    Malonyl-CoA:acyl-carrier protein transacylase (MCAT), which transfers the malonyl group from malonyl-CoA to holo-acyl carrier protein (ACP), is a key enzyme in fatty acid biosynthesis. Schizochytrium sp. TIO1101 is a marine protist with high levels of docosahexaenoic acid accumulation. In this study, the putative fabD gene coding MCAT was isolated from Schizochytrium sp. TIO1101. The Schizochytrium MCAT gene (ScTIOfabD) contained an 1176 bp open reading frame encoding a protein of 391 amino acids. The ScTIOfabD gene exhibited high novelty in nucleotide and amino acid sequence. The highest amino acid identity was only 35 % between ScTIOMCAT and the reported MCATs. Further studies demonstrated that ScTIOMCAT could bind malonyl-CoA directly and transfer malonyl group from malonyl-CoA to the ACP domain in vitro. Phylogenetic analysis suggested that ScTIOMCAT was relative close to MCATs of yeast strains. Overexpression of ScTIOMCAT in Saccharomyces cereviseae significantly increased the MCAT activity, without negative effects on the growth rate of the host strain. In addition, ScTIOMCAT generated 16.8 and 62 % increase in biomass and fatty acid accumulation, respectively, and did not alter the profile of fatty acid. Our results indicated that the novel MCAT gene from Schizochytrium sp. TIO1101 was crucial for fatty acid synthesis and had potential applications for genetic modifications of oil-producing species.

  6. Pyromellitic acid produced from coal. Kwas piromelitowy z wegla

    Energy Technology Data Exchange (ETDEWEB)

    Salbut, P.D.; Kutkiewicz, K.; Berlozecki, S.

    1986-01-01

    A procedure for pyromellitic acid production from coal in a two-stage process of oxidation and decarboxylation has been presented. As a result of controlled coal oxidation in an alkaline medium, a mixture of sodium or potassium salts of polycarboxylic acids has been obtained. In the second stage of the process, the mixture of these salts has been selectively decarboxylated in a medium of sulphuric acid and sodium or potassium bisulphate. As a result of decarboxylation of mellitic and pentacarboxylic acids occurring among the coal oxidation products, pyromellitic acid and a mixture of benzenedi-, tri- and tetracarboxylic acids have been obtained. The kinetics of the decarboxylation process have been examined. More favourable reaction course has been found in the case of reaction medium containing potassium bisulphate. 1 fig., 6 tabs.

  7. Repeated-batch fermentation of lignocellulosic hydrolysate to ethanol using a hybrid Saccharomyces cerevisiae strain metabolically engineered for tolerance to acetic and formic acids.

    Science.gov (United States)

    Sanda, Tomoya; Hasunuma, Tomohisa; Matsuda, Fumio; Kondo, Akihiko

    2011-09-01

    A major challenge associated with the fermentation of lignocellulose-derived hydrolysates is improved ethanol production in the presence of fermentation inhibitors, such as acetic and formic acids. Enhancement of transaldolase (TAL) and formate dehydrogenase (FDH) activities through metabolic engineering successfully conferred resistance to weak acids in a recombinant xylose-fermenting Saccharomyces cerevisiae strain. Moreover, hybridization of the metabolically engineered yeast strain improved ethanol production from xylose in the presence of both 30 mM acetate and 20mM formate. Batch fermentation of lignocellulosic hydrolysate containing a mixture of glucose, fructose and xylose as carbon sources, as well as the fermentation inhibitors, acetate and formate, was performed for five cycles without any loss of fermentation capacity. Long-term stability of ethanol production in the fermentation phase was not only attributed to the coexpression of TAL and FDH genes, but also the hybridization of haploid strains.

  8. Novel Lactate Transporters from Carboxylic Acid-Producing Rhizopus

    Science.gov (United States)

    The fungus Rhizopus is frequently used for fermentative production of lactic acid, but little is known about the mechanisms or proteins for transporting this carboxylic acid. Since transport of the lactate anion across the plasma membrane is critical to prevent acidification of the cytoplasm, we ev...

  9. Rapid detection method for fusaric acid-producing species of Fusarium by PCR

    Science.gov (United States)

    Fusaric acid is a mycotoxin produced by species of the fungus Fusarium and can act synergistically with other Fusarium toxins. In order to develop a specific detection method for fusaric acid-producing fungus, PCR prim¬ers were designed to amplify FUB10, a transcription factor gene in fusaric acid ...

  10. [Improvement of acetic acid tolerance and fermentation performance of industrial Saccharomyces cerevisiae by overexpression of flocculent gene FLO1 and FLO1c].

    Science.gov (United States)

    Du, Zhaoli; Cheng, Yanfei; Zhu, Hui; He, Xiuping; Zhang, Borun

    2015-02-01

    Flocculent gene FLO1 and its truncated form FLO1c with complete deletion of repeat unit C were expressed in a non-flocculent industrial strain Saccharomyces cerevisiae CE6 to generate recombinant flocculent strains 6-AF1 and 6-AF1c respectively. Both strains of 6-AF1 and 6-AF1c displayed strong flocculation and better cell growth than the control strain CE6-V carrying the empty vector under acetic acid stress. Moreover, the flocculent strains converted glucose to ethanol at much higher rates than the control strain CE6-V under acetic acid stress. In the presence of 0.6% (V/V) acetic acid, the average ethanol production rates of 6-AF1 and 6-AF1c were 1.56 and 1.62 times of that of strain CE6-V, while the ethanol production rates of 6-AF1 and 6-AF1c were 1.21 and 1.78 times of that of strain CE6-V under 1.0% acetic acid stress. Results in this study indicate that acetic acid tolerance and fermentation performance of industrial S. cerevisiae under acetic acid stress can be improved largely by flocculation endowed by expression of flocculent genes, especially FLO1c.

  11. RNA-Seq-based transcriptomic and metabolomic analysis reveal stress responses and programmed cell death induced by acetic acid in Saccharomyces cerevisiae

    Science.gov (United States)

    Dong, Yachen; Hu, Jingjin; Fan, Linlin; Chen, Qihe

    2017-01-01

    As a typical harmful inhibitor in cellulosic hydrolyzates, acetic acid not only hinders bioethanol production, but also induces cell death in Saccharomyces cerevisiae. Herein, we conducted both transcriptomic and metabolomic analyses to investigate the global responses under acetic acid stress at different stages. There were 295 up-regulated and 427 down-regulated genes identified at more than two time points during acetic acid treatment (150 mM, pH 3.0). These differentially expressed genes (DEGs) were mainly involved in intracellular homeostasis, central metabolic pathway, transcription regulation, protein folding and stabilization, ubiquitin-dependent protein catabolic process, vesicle-mediated transport, protein synthesis, MAPK signaling pathways, cell cycle, programmed cell death, etc. The interaction network of all identified DEGs was constructed to speculate the potential regulatory genes and dominant pathways in response to acetic acid. The transcriptional changes were confirmed by metabolic profiles and phenotypic analysis. Acetic acid resulted in severe acidification in both cytosol and mitochondria, which was different from the effect of extracellular pH. Additionally, the imbalance of intracellular acetylation was shown to aggravate cell death under this stress. Overall, this work provides a novel and comprehensive understanding of stress responses and programmed cell death induced by acetic acid in yeast. PMID:28209995

  12. Contribution of the tricarboxylic acid (TCA) cycle and the glyoxylate shunt in Saccharomyces cerevisiae to succinic acid production during dough fermentation.

    Science.gov (United States)

    Rezaei, Mohammad N; Aslankoohi, Elham; Verstrepen, Kevin J; Courtin, Christophe M

    2015-07-02

    Succinic acid produced by yeast during bread dough fermentation can significantly affect the rheological properties of the dough. By introducing mutations in the model S288C yeast strain, we show that the oxidative pathway of the TCA cycle and the glyoxylate shunt contribute significantly to succinic acid production during dough fermentation. More specifically, deletion of ACO1 and double deletion of ACO1 and ICL1 resulted in a 36 and 77% decrease in succinic acid levels in fermented dough, respectively. Similarly, double deletion of IDH1 and IDP1 decreased succinic acid production by 85%, while also affecting the fermentation rate. By contrast, double deletion of SDH1 and SDH2 resulted in a two-fold higher succinic acid accumulation compared to the wild-type. Deletion of fumarate reductase activity (FRD1 and OSM1) in the reductive pathway of the TCA cycle did not affect the fermentation rate and succinic acid production. The changes in the levels of succinic acid produced by mutants Δidh1Δidp1 (low level) and Δsdh1Δsdh2 (high level) in fermented dough only resulted in small pH differences, reflecting the buffering capacity of dough at a pH of around 5.1. Moreover, Rheofermentometer analysis using these mutants revealed no difference in maximum dough height and gas retention capacity with the dough prepared with S288C. The impact of the changed succinic acid profile on the organoleptic or antimicrobial properties of bread remains to be demonstrated.

  13. Method for producing 3-hydroxypropionic acid and other products

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, Michael D.; Gill, Ryan T.; Lipscomb, Tanya E.W.

    2016-08-30

    This invention relates to metabolically engineered microorganism strains, such as bacterial strains, in which there is an increased utilization of malonyl-CoA for production of a chemical product, which includes 3-hydroxypropionic acid.

  14. Methods for producing 3-hydroxypropionic acid and other products

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, Michael D.; Gill, Ryan T.; Lipscomb, Tanya E. W.

    2016-07-12

    This invention relates to metabolically engineered microorganism strains, such as bacterial strains, in which there is an increased utilization of malonyl-CoA for production of a chemical product, which includes 3-hydroxypropionic acid.

  15. Data set for cloning and characterization of heterologous transporters in Saccharomyces cerevisiae and identification of important amino acids for xylose utilization

    Directory of Open Access Journals (Sweden)

    Chengqiang Wang

    2015-09-01

    Full Text Available The efficient uptake is important for the xylose utilization by Saccharomyces cerevisiae. A heterogenous transporter Mgt05196p was cloned from Meyerozyma guilliermondii and expressed in Saccharomyces cerevisiae [1]. This data article contains the transport characteristics of Mgt05196p in S. cerevisiae. The fluorescence of fusion protein Mgt05196p-GFP expressing strain was located on the cell surface demonstrated that the heterogenous transporter Mgt05196p was targeted to the plasma membrane of S. cerevisiae. The expressing of Mgt05196p in the hxt null S. cerevisiae endowed the strain with the glucose and d-xylose absorption capacity, as well as expressing the native d-xylose transporter Gal2p. The transmembrane domains of Mgt05196p were predicted and compared with the XylEp, whose crystal structure was revealed. And then, the homologous modeling of Mgt05196p was built basing on the XylEp to find out the crucial amino acid residues for sugars binding and transport.

  16. Effects of ethanol, octanoic and decanoic acids of fermentation and the passive influx of protons through the plasma membrane of Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, S. (Nietvoorbij Inst. of Viticulture and Oenology, Stellenbosch (South Africa)); Hofmeyr, J.H.S. (Dept. of Biochemistry and Inst. of Biotechnology, Stellenbosch Univ. (South Africa))

    1993-02-01

    Ethanol, octanoic and decanoic acids are known toxic products of alcoholic fermentation and inhibit yeast functions such as growth and fermentation. pH-stat measurements showed that, in a concentration range up to 20 mg/l, octanoic and decaonoic acids increase the rate of passive H[sup +] influx across the plama membrane of Saccharomyces cerevisiae IGC 3507. Decanoic acid was more active than octanoic acid, which agrees with its higher liposolubility. The fatty acids probably act as H[sup +] carriers, since the magnitude of the effect depended on pH and correlated with the concentration of protonated fatty acids. Esterification of the fatty acids partially abolished the enhancing effect on passive H[sup +] influx. Passive H[sup +] influx showed saturation kinetics with half-maximal activity at 6.6 [mu]M H[sup +] (pH 5.2). Contrary to previous findings, ethanol inhibited H[sup +] influx exponentially up to a concentration of 8% (v/v). At higher concentrations, ethanol reactivated H[sup +] influx; the original rate of H[sup +] uptake was reached at 14% (v/v) ethanol. In the same concentration ranges that affected passive H[sup +] influx, ethanol, octanoic and decanoic acids inhibited the fermentation rate. This inhibitory effect of the fatty acids on fermentation rate depended on liposolubility, pH, and esterification in the same way as that found for their effect on passive H[sup +] influx. Inhibition of fermentation by octanoic and decanoic acids could therefore result from their effect on the rate of passive H[sup +] influx. (orig.).

  17. Improved ethanol production from xylose in the presence of acetic acid by the overexpression of the HAA1 gene in Saccharomyces cerevisiae.

    Science.gov (United States)

    Sakihama, Yuri; Hasunuma, Tomohisa; Kondo, Akihiko

    2015-03-01

    The hydrolysis of lignocellulosic biomass liberates sugars, primarily glucose and xylose, which are subsequently converted to ethanol by microbial fermentation. The rapid and efficient fermentation of xylose by recombinant Saccharomyces cerevisiae strains is limited by weak acids generated during biomass pretreatment processes. In particular, acetic acid negatively affects cell growth, xylose fermentation rate, and ethanol production. The ability of S. cerevisiae to efficiently utilize xylose in the presence of acetic acid is an essential requirement for the cost-effective production of ethanol from lignocellulosic hydrolysates. Here, an acetic acid-responsive transcriptional activator, HAA1, was overexpressed in a recombinant xylose-fermenting S. cerevisiae strain to yield BY4741X/HAA1. This strain exhibited improved cell growth and ethanol production from xylose under aerobic and oxygen limited conditions, respectively, in the presence of acetic acid. The HAA1p regulon enhanced transcript levels in BY4741X/HAA1. The disruption of PHO13, a p-nitrophenylphosphatase gene, in BY4741X/HAA1 led to further improvement in both yeast growth and the ability to ferment xylose, indicating that HAA1 overexpression and PHO13 deletion act by different mechanisms to enhance ethanol production.

  18. Study on the Technology of Fermentation with Acid-resistant Saccharomyces sake A%耐酸性清酒酵母A发酵工艺研究

    Institute of Scientific and Technical Information of China (English)

    蒋军; 吴天祥; 李运华

    2009-01-01

    [目的]为生产优质清酒奠定理论基础.[方法]以优质粳米为原料,在单因素试验的基础上,采用正交试验法研究耐酸性清酒酵母A的发酵规律.[结果]水料比为1~2时,清酒酒精度较高.水料比为0.5时,发酵醪的糖浓度和渗透压较高.水料比为3时,发酵醪的淀粉浓度降低,清酒酒精度低.酒母量为20%时,利于清酒双边发酵,清酒的可溶物含量约为11%.米曲量为30%~50%时,清酒色度低,苦涩味轻.乳酸添加量为8‰~12‰时,发酵结束后米曲中糖化酶的活力约为290 mg/(g·h).乳酸量超过12‰时,酶活力下降比较快,清酒有异杂味感.15 ℃下发酵21 d的清酒酒精度达17.1% (V/V),淀粉利用率为88.1%.[结论]利用耐酸性清酒酵母发酵生产清酒,简化了生产工艺,缩短了发酵时间,提高了原料利用率.%[Objective]The purpose of the study was to lay a theoretical foundation for producing high-quality sake. [Method]With high-quality round shaped rice as raw material, on the basis of single factor experiment, the fermentation law of acid-resistant Saccharomyces sake A was studied through orthogonal experiment. [Result]When the water-material ratio was 1-2, the alcohol degree of sake was higher. When the water-material ratio was 0.5, the sugar concentration and osmotic pressure of fermenting mash were higher. When the water-material ratio was 3, the starch concentration of fermenting mash was decreased and the alcohol degree of sake was low. When the seeding yeast dosage was 20%, it was favorable to the dual fermentation of sake and the soluble content of sake was about 11%. When the rice starter dosage was 30%-50%, the sake had low colority and light bitterness and astringency. When the lactic addition was 8‰-12‰, the activity of Aspergillus oryzae was about 290 mg/g when the fermentation was finished. When the lactic content was higher than 12‰, the enzyme activity was decreased faster and the sake had off-flavors. The

  19. Identification of amino acids involved in the Flo11p-mediated adhesion of Saccharomyces cerevisiae to a polystyrene surface using phage display with competitive elution

    DEFF Research Database (Denmark)

    Mortensen, Henrik Dam; Dupont, Kitt; Jespersen, Lene;

    2007-01-01

    . cerevisiae FLO11 wild-type (TBR1) cells had a higher consensus than those from competitive panning with S. cerevisiae flo11¿ mutant (TBR5) cells, suggesting that the wild-type cells interact with the plastic surface in a stronger and more similar way than the mutant cells. Tryptophan and proline were more...... a phage with a hydrophobic peptide containing no tryptophan and only two proline residues. Conclusions: Our results suggest a key role of tryptophan and proline in the hydrophobic interactions between Flo11p on the S. cerevisiae cell surface and the PolySorp surface. Significance and Impact of the Study......Aims: To identify the main amino acids involved in the Flo11p-mediated adhesion of Saccharomyces cerevisiae to the polystyrene surface PolySorp. Methods and Results: Using a combination of phage display and competitive elution revealed that 12-mer peptides of phages from competitive panning with S...

  20. Metabolic pathway engineering based on metabolomics confers acetic and formic acid tolerance to a recombinant xylose-fermenting strain of Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Ishii Jun

    2011-01-01

    Full Text Available Abstract Background The development of novel yeast strains with increased tolerance toward inhibitors in lignocellulosic hydrolysates is highly desirable for the production of bio-ethanol. Weak organic acids such as acetic and formic acids are necessarily released during the pretreatment (i.e. solubilization and hydrolysis of lignocelluloses, which negatively affect microbial growth and ethanol production. However, since the mode of toxicity is complicated, genetic engineering strategies addressing yeast tolerance to weak organic acids have been rare. Thus, enhanced basic research is expected to identify target genes for improved weak acid tolerance. Results In this study, the effect of acetic acid on xylose fermentation was analyzed by examining metabolite profiles in a recombinant xylose-fermenting strain of Saccharomyces cerevisiae. Metabolome analysis revealed that metabolites involved in the non-oxidative pentose phosphate pathway (PPP [e.g. sedoheptulose-7-phosphate, ribulose-5-phosphate, ribose-5-phosphate and erythrose-4-phosphate] were significantly accumulated by the addition of acetate, indicating the possibility that acetic acid slows down the flux of the pathway. Accordingly, a gene encoding a PPP-related enzyme, transaldolase or transketolase, was overexpressed in the xylose-fermenting yeast, which successfully conferred increased ethanol productivity in the presence of acetic and formic acid. Conclusions Our metabolomic approach revealed one of the molecular events underlying the response to acetic acid and focuses attention on the non-oxidative PPP as a target for metabolic engineering. An important challenge for metabolic engineering is identification of gene targets that have material importance. This study has demonstrated that metabolomics is a powerful tool to develop rational strategies to confer tolerance to stress through genetic engineering.

  1. Producing biodiesel from yellow greases with high free fatty acids

    Directory of Open Access Journals (Sweden)

    Amrani Mahacine

    2007-01-01

    Full Text Available Biodiesel is a diesel replacement fuel that is manufactured from vegetable oils recycled cooking greases and oils or animal fats. Biodiesel offers many advantages because it is renewable, nontoxic, biodegradable, and suitable for sensitive environments. It can also be used in most diesel equipments with no or only minor modifications. These yellow greases contain great quantities of free fatty acids which form soaps in the presence of alkaline catalyst. Pretreatments of the raw material with acid catalysts are necessary to avoid the soap formation. The transesterification of yellow greases is supplemented in the presence of an alkaline catalyst. The greatest production of biodiesel corresponds to molar flows of 4.985 kmol.hr-1 of methyl oleate, and 4.658 kmol.hr-1 of methyl butyrate.

  2. Improved growth and ethanol fermentation of Saccharomyces cerevisiae in the presence of acetic acid by overexpression of SET5 and PPR1.

    Science.gov (United States)

    Zhang, Ming-Ming; Zhao, Xin-Qing; Cheng, Cheng; Bai, Feng-Wu

    2015-12-01

    To better understand the contribution of zinc-finger proteins to environmental stress tolerance, particularly inhibition from acetic acid, which is a potent inhibitor for cellulosic ethanol production by microbial fermentations, SET5 and PPR1 were overexpressed in Saccharomyces cerevisiae BY4741. With 5 g/L acetic acid addition, engineered strains BY4741/SET5 and BY4741/PPR1 showed improved growth and enhanced ethanol fermentation performance compared to that with the control strain. Similar results were also observed in ethanol production using corn stover hydrolysate. Further studies indicated that SET5 and PPR1 overexpression in S. cerevisiae significantly improved activities of antioxidant enzymes and ATP generation in the presence of acetic acid, and consequently decreased intracellular accumulation of reactive oxygen species (50.9 and 45.7%, respectively). These results revealed the novel functions of SET5 and PPR1 for the improvement of yeast acetic acid tolerance, and also implicated the involvement of these proteins in oxidative stress defense and energy metabolism in S. cerevisiae. This work also demonstrated that overexpression of SET5 and PPR1 would be a feasible strategy to increase cellulosic ethanol production efficiency.

  3. Comparative genomics of citric-acid-producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88

    NARCIS (Netherlands)

    Andersen, M.R.; Salazar, M.P.; Schaap, P.J.

    2011-01-01

    The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme-p

  4. Comparative genomics of citric-acid-producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88

    DEFF Research Database (Denmark)

    Andersen, Mikael Rørdam; Salazar, Margarita Pena; Schaap, Peter J.

    2011-01-01

    The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzym...

  5. TREATMENT AND RESOURCE REUSE OF 1,2,4-ACID PRODUCING EFFLUENT WITH MACROPOROUS POLYMERIC ADSORBENT

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The treatment and resource reuse of 1,2,4-acid producing wastewater by self-mademacroporous adsorption resin ND,A-107 was studied in this paper. Optimum adsorption anddesorption process parameters were acquired by systematically study. The polymeric resin NDA-10 7indicated good adsorption & desorption of 1,2, 4-acid in the wastewater. The removal efficiency of1,2,4-acid, CODer is about 78%, 72% respectively. It is evident that this adsorption process is anefficient treatment method for 1,2,4-acid producing wastewater. At the same time, the accumulationand resource reuse of l,2, 4-acid can be realized in this process.

  6. Saccharomyces species in the Production of Beer

    Directory of Open Access Journals (Sweden)

    Graham G. Stewart

    2016-12-01

    Full Text Available The characteristic flavour and aroma of any beer is, in large part, determined by the yeast strain employed and the wort composition. In addition, properties such as flocculation, wort fermentation ability (including the uptake of wort sugars, amino acids, and peptides, ethanol and osmotic pressure tolerance together with oxygen requirements have a critical impact on fermentation performance. Yeast management between fermentations is also a critical brewing parameter. Brewer’s yeasts are mostly part of the genus Saccharomyces. Ale yeasts belong to the species Saccharomyces cerevisiae and lager yeasts to the species Saccharomyces pastorianus. The latter is an interspecies hybrid between S. cerevisiae and Saccharomyces eubayanus. Brewer’s yeast strains are facultative anaerobes—they are able to grow in the presence or absence of oxygen and this ability supports their property as an important industrial microorganism. This article covers important aspects of Saccharomyces molecular biology, physiology, and metabolism that is involved in wort fermentation and beer production.

  7. Oscillations Produced From Acidity Hydrolysis of Triglyceride inEmulsion

    Institute of Scientific and Technical Information of China (English)

    HE, Zhan-Bo; QI, Gang

    2001-01-01

    A new type of oscillating reaction was found from the systematic cesign of the chemical oscillator in water in oil (W/O)emulsions. It is an acidity hydrolysis reaction of long chaintriglyceride in W/O emulsion at 25.0 ± 0. I°C in a bath stirring reactor. During the proeess of reaction, there were periodic and semi-periodic changes lasting more than 10 hoursboth in electrolytic conductivity and electric potential. Microscope also revealed that the emulsion structure changed regularly and puikly. Became of the large differnce in the solubility of the hydrolyzed products, it could be thought, that thediffernt redistribution in the two phases of water and oil induces the regular changes. Marangoni effect of interfacemembrane made oscillation to form. TITne oscillating reactioncan be used to explain the periodic change in the living systemprodrced from coupling between reaction and diffusion.

  8. Myristic Acid Produces Anxiolytic-Like Effects in Wistar Rats in the Elevated Plus Maze

    Directory of Open Access Journals (Sweden)

    Carlos M. Contreras

    2014-01-01

    Full Text Available A mixture of eight fatty acids (linoleic, palmitic, stearic, myristic, elaidic, lauric, oleic, and palmitoleic acids at similar concentrations identified in human amniotic fluid produces anxiolytic-like effects comparable to diazepam in Wistar rats. However, individual effects of each fatty acid remain unexplored. In Wistar rats, we evaluated the separate action of each fatty acid at the corresponding concentrations previously found in human amniotic fluid on anxiety-like behaviour. Individual effects were compared with vehicle, an artificial mixture of the same eight fatty acids, and a reference anxiolytic drug (diazepam, 2 mg/kg. Myristic acid, the fatty acid mixture, and diazepam increased the time spent in the open arms of the elevated plus maze and reduced the anxiety index compared with vehicle, without altering general locomotor activity. The other fatty acids had no effect on anxiety-like behaviour, but oleic acid reduced locomotor activity. Additionally, myristic acid produced anxiolytic-like effects only when the concentration corresponded to the one identified in human amniotic fluid (30 g/mL but did not alter locomotor activity. We conclude that of the eight fatty acids contained in the fatty acid mixture, only myristic acid produces anxiolytic-like effects when administered individually at a similar concentration detected in human amniotic fluid.

  9. 产β-胡萝卜素酿酒酵母工程菌的构建%Construction of engineering Saccharomyces cerevisiae producing β-carotene

    Institute of Scientific and Technical Information of China (English)

    高书良; 朱丽; 蒋宇; 戈梅; 杨晟; 陈代杰

    2013-01-01

    以酿酒酵母Saccharomyces cerevisiae BY4742 为宿主菌,利用DNA 组装(DNA assemble)技 术,向宿主菌导入了β-胡萝卜素合成途径,表达了源自Xanthophyllomyces dendrorhous 的CrtE,CrtYB 和CrtI 3 个基因,获得了一株染色体整合型工程菌株HCCB08531,β-胡萝卜素产量达3.68 mg/ g 干重.

  10. Effects of long-term dietary supplementation of monensin or saccharomyces cerevisiae on blood acid-base and productive performance in growing feedlot steers.

    Science.gov (United States)

    Castillo, Cristina; Benedito, José Luis; Méndez, Jesús; García-Partida, Paulino; Vázquez, Patricia; Pereira, Victor; López-Alonso, Marta; Hernández, Joaquín

    2006-01-01

    The aim of this study was to evaluate the effects of two dietary supplements (monensin and a live yeast culture) on acid-base balance in steers maintained in a commercial feedlot system, considering effects over the growing period (14 to 23 weeks of age). A 63-day feedlot study was performed using 42 double-muscled Belgian Blue steers. Steers were allotted randomly to one of the three study groups: (1) control group [no supplementation, C], (2) monensin supplementation [MON] at a concentration of 30 mg/kg (DM basis), and (3) live Saccharomyces cerevisiae strain supplementation [SACC] at a dose of 500 mg/kg (DM basis). Venous blood samples were collected for the measurement of acid-base parameters and L-lactate. Production parameters were also used as a complementary tool for understanding the internal changes associated with supplementation. Our results show that during the study period no statistical differences were observed between supplemented and control steers, although non-supplemented animals tended to gain more efficiently than those fed monensin or yeast. Nevertheless, taking into account blood parameters, these control animals showed a greater risk of acid overload due to a more marked decline in blood buffer levels over time in comparison with supplemented steers although no differences were observed between monensin or yeast supplemented animals. Additionally, significant effect of supplementation was observed in packed cell volume (PCV) values.

  11. An organic acid-tolerant HAA1-overexpression mutant of an industrial bioethanol strain of Saccharomyces cerevisiae and its application to the production of bioethanol from sugarcane molasses.

    Science.gov (United States)

    Inaba, Takuya; Watanabe, Daisuke; Yoshiyama, Yoko; Tanaka, Koichi; Ogawa, Jun; Takagi, Hiroshi; Shimoi, Hitoshi; Shima, Jun

    2013-12-30

    Bacterial contamination is known as a major cause of the reduction in ethanol yield during bioethanol production by Saccharomyces cerevisiae. Acetate is an effective agent for the prevention of bacterial contamination, but it negatively affects the fermentation ability of S. cerevisiae. We have proposed that the combined use of organic acids including acetate and lactate and yeast strains tolerant to organic acids may be effective for the elimination of principally lactic acid bacterial (LAB) contamination. In a previous study employing laboratory S. cerevisiae strains, we showed that overexpression of the HAA1 gene, which encodes a transcriptional activator, could be a useful molecular breeding method for acetate-tolerant yeast strains. In the present study, we constructed a HAA1-overexpressing diploid strain (MATa/α, named ER HAA1-OP) derived from the industrial bioethanol strain Ethanol Red (ER). ER HAA1-OP showed tolerance not only to acetate but also to lactate, and this tolerance was dependent on the increased expression of HAA1 gene. The ethanol production ability of ER HAA1-OP was almost equivalent to that of the parent strain during the bioethanol production process from sugarcane molasses in the absence of acetate. The addition of acetate at 0.5% (w/v, pH 4.5) inhibited the fermentation ability of the parent strain, but such an inhibition was not observed in the ethanol production process using ER HAA1-OP.

  12. Oleanolic acid alters bile acid metabolism and produces cholestatic liver injury in mice.

    Science.gov (United States)

    Liu, Jie; Lu, Yuan-Fu; Zhang, Youcai; Wu, Kai Connie; Fan, Fang; Klaassen, Curtis D

    2013-11-01

    Oleanolic acid (OA) is a triterpenoids that exists widely in plants. OA is effective in protecting against hepatotoxicants. Whereas a low dose of OA is hepatoprotective, higher doses and longer-term use of OA produce liver injury. This study characterized OA-induced liver injury in mice. Adult C57BL/6 mice were given OA at doses of 0, 22.5, 45, 90, and 135 mg/kg, s.c., daily for 5 days, and liver injury was observed at doses of 90 mg/kg and above, as evidenced by increases in serum activities of alanine aminotransferase and alkaline phosphatase, increases in serum total bilirubin, as well as by liver histopathology. OA-induced cholestatic liver injury was further evidenced by marked increases of both unconjugated and conjugated bile acids (BAs) in serum. Gene and protein expression analysis suggested that livers of OA-treated mice had adaptive responses to prevent BA accumulation by suppressing BA biosynthetic enzyme genes (Cyp7a1, 8b1, 27a1, and 7b1); lowering BA uptake transporters (Ntcp and Oatp1b2); and increasing a BA efflux transporter (Ostβ). OA increased the expression of Nrf2 and its target gene, Nqo1, but decreased the expression of AhR, CAR and PPARα along with their target genes, Cyp1a2, Cyp2b10 and Cyp4a10. OA had minimal effects on PXR and Cyp3a11. Taken together, the present study characterized OA-induced liver injury, which is associated with altered BA homeostasis, and alerts its toxicity potential.

  13. Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Bojsen, Rasmus K; Andersen, Kaj Scherz; Regenberg, Birgitte

    2012-01-01

    Microbial biofilms can be defined as multi-cellular aggregates adhering to a surface and embedded in an extracellular matrix (ECM). The nonpathogenic yeast, Saccharomyces cerevisiae, follows the common traits of microbial biofilms with cell-cell and cell-surface adhesion. S. cerevisiae is shown...... pathways including the protein kinase A and a mitogen-activated protein kinase pathway. Advanced genetic tools and resources have been developed for S. cerevisiae including a deletion mutant-strain collection in a biofilm-forming strain background and GFP-fusion protein collections. Furthermore, S....... cerevisiae biofilm is well applied for confocal laser scanning microscopy and fluorophore tagging of proteins, DNA and RNA. These techniques can be used to uncover the molecular mechanisms for biofilm development, drug resistance and for the study of molecular interactions, cell response to environmental...

  14. A simple plate-assay for the screening of L-malic acid producing microorganisms.

    Science.gov (United States)

    Peleg, Y; Rokem, J S; Goldberg, I

    1990-02-01

    A simple plate-assay has been developed to screen microorganisms for L-malic acid production. Acid producing organisms were identified, after microbial colony growth on media containing glucose or fumaric acid as sole carbons sources, by formation of a dark halo of formazan. The halo was observed when the plate was covered with a soft agar overlay containing NAD(+)-malate dehydrogenase, NAD+, phenazine methosulfate (PMS) and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT). The assay developed is simple, specific for L-malic acid and therefore can be used to identify L-malic acid producing filamentous fungi using glucose as carbon source (e.g. Aspergillus strains). The assay is also applicable for screening bacteria with high fumarase activity, able to convert fumaric acid to L-malic acid.

  15. Targeted mutation of Δ12 and Δ15 desaturase genes in hemp produce major alterations in seed fatty acid composition including a high oleic hemp oil.

    Science.gov (United States)

    Bielecka, Monika; Kaminski, Filip; Adams, Ian; Poulson, Helen; Sloan, Raymond; Li, Yi; Larson, Tony R; Winzer, Thilo; Graham, Ian A

    2014-06-01

    We used expressed sequence tag library and whole genome sequence mining to identify a suite of putative desaturase genes representing the four main activities required for production of polyunsaturated fatty acids in hemp seed oil. Phylogenetic-based classification and developing seed transcriptome analysis informed selection for further analysis of one of seven Δ12 desaturases and one of three Δ15 desaturases that we designate CSFAD2A and CSFAD3A, respectively. Heterologous expression of corresponding cDNAs in Saccharomyces cerevisiae showed CSFAD2A to have Δx+3 activity, while CSFAD3A activity was exclusively at the Δ15 position. TILLING of an ethyl methane sulphonate mutagenized population identified multiple alleles including non-sense mutations in both genes and fatty acid composition of seed oil confirmed these to be the major Δ12 and Δ15 desaturases in developing hemp seed. Following four backcrosses and sibling crosses to achieve homozygosity, csfad2a-1 was grown in the field and found to produce a 70 molar per cent high oleic acid (18:1(Δ9) ) oil at yields similar to wild type. Cold-pressed high oleic oil produced fewer volatiles and had a sevenfold increase in shelf life compared to wild type. Two low abundance octadecadienoic acids, 18:2(Δ6,9) and 18:2(Δ9,15), were identified in the high oleic oil, and their presence suggests remaining endogenous desaturase activities utilize the increased levels of oleic acid as substrate. Consistent with this, CSFAD3A produces 18:2(Δ9,15) from endogenous 18:1(Δ9) when expressed in S. cerevisiae. This work lays the foundation for the development of additional novel oil varieties in this multipurpose low input crop.

  16. Improved production of fatty acids by Saccharomyces cerevisiae through screening a cDNA library from the oleaginous yeast Yarrowia lipolytica.

    Science.gov (United States)

    Shi, Shuobo; Ji, Haichuan; Siewers, Verena; Nielsen, Jens

    2016-02-01

    Biological production of fatty acid (FA)-derived products has gained increasing attention to replace petroleum-based fuels and chemicals. FA biosynthesis is highly regulated, and usually it is challenging to design rational engineering strategies. In addition, the conventional 'one sample at a time' method for lipid determination is time consuming and laborious, and it is difficult to screen large numbers of samples. Here, a method for detecting free FAs in viable cells using Nile red staining was developed for use in large-scale screening. Following optimization of the method, it was used for screening a cDNA library from the oleaginous yeast Yarrowia lipolytica for identification of genes/enzymes that were able to enhance free FA accumulation in Saccharomyces cerevisiae. Several novel enzymes resulting in increasing FA accumulation were discovered. These targets include a GPI anchor protein, malate dehydrogenase, glyceraldehyde 3-phosphate dehydrogenase, FA hydroxylase, farnesyltransferase, anoctamin, dihydrolipoamide dehydrogenase and phosphatidylethanolamine-binding protein. The best enzyme resulted in a 2.5-fold improvement in production of free FAs. Our findings not only provide a novel method for high-throughput evaluation of the content of free FAs, but also give new insight into how enzymes from Y. lipolytica may increase the production of fatty acids in S. cerevisiae.

  17. Screening of Saccharomyces Strains Highly Producing Glutathione and Breeding of Its Ethionine-resistant Mutants%高产谷胱甘肽酵母菌株的筛选及其抗乙硫氨酸诱变研究

    Institute of Scientific and Technical Information of China (English)

    冮洁; 单立峰; 吴耘红; 张鹭

    2008-01-01

    [Objective] The aim of this study was to screen Saccharomyces for glutathione over-production. [Method] Ethionine-resistant mutants were obtained through UV mutagenesis and rational screening. [Result] A high GSH-producing strain HSJB1 was isolated from soil, and the biomass for this strain by flask shaking fermentation was 3.87 g/L while the GSH yield was 91.87 mg/L. According to the morphological, physiological and biochemical characteristics of cells, this strain was primarily identified as Saccharomyces cerevisiae. An ethionine-resistant mutant YBS77 was obtained through UV mutagenesis of the original strain HSJB1, and the biomass for this strain by flask shaking fermentation was 7.60 g dry cell weight/L while the GSH yield was 211.96 mg/L. [Conclusion] The biomass of the mutant obtained by breeding is increased by 96.38% than that of the original strain, and the GSH yield of the mutant obtained by breeding is increased by 130.72% than that from the original strain, which indicates that the breeding method is feasible.

  18. Involvement of Vacuolar Sequestration and Active Transport in Tolerance of Saccharomyces cerevisiae to Hop Iso-α-Acids

    NARCIS (Netherlands)

    Hazelwood, L.A.; Walsh, M.C.; Pronk, J.T.; Daran, J.M.

    2009-01-01

    The hop plant, Humulus lupulus L., has an exceptionally high content of secondary metabolites, the hop -acids, which possess a range of beneficial properties, including antiseptic action. Studies performed on the mode of action of hop iso--acids have hitherto been restricted to lactic acid bacteria.

  19. Fermentative capabilities and volatile compounds produced by Kloeckera/Hanseniaspora and Saccharomyces yeast strains in pure and mixed cultures during Agave tequilana juice fermentation.

    Science.gov (United States)

    González-Robles, Ivonne Wendolyne; Estarrón-Espinosa, Mirna; Díaz-Montaño, Dulce María

    2015-09-01

    The fermentative and aromatic capabilities of Kloeckera africana/Hanseniaspora vineae K1, K. apiculata/H. uvarum K2, and Saccharomyces cerevisiae S1 and S2 were studied in pure and mixed culture fermentations using Agave tequila juice as the culture medium. In pure and mixed cultures, Kloeckera/Hanseniaspora strains showed limited growth and sugar consumption, as well as low ethanol yield and productivity, compared to S. cerevisiae, which yielded more biomass, ethanol and viable cell concentrations. In pure and mixed cultures, S. cerevisiae presented a similar behaviour reaching high biomass production, completely consuming the sugar, leading to high ethanol production. Furthermore, the presence of S. cerevisiae strains in the mixed cultures promoted the production of higher alcohols, acetaldehyde and ethyl esters, whereas Kloeckera/Hanseniaspora strains stimulated the production of ethyl acetate and 2-phenyl ethyl acetate compounds.

  20. Comparative genomics of citric-acid producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Mikael R.; Salazar, Margarita; Schaap, Peter; van de Vondervoort, Peter; Culley, David E.; Thykaer, Jette; Frisvad, Jens C.; Nielsen, Kristian F.; Albang, Richard; Albermann, Kaj; Berka, Randy; Braus, Gerhard; Braus-Stromeyer, Susanna A.; Corrochano, Luis; Dai, Ziyu; van Dijck, Piet; Hofmann, Gerald; Lasure, Linda L.; Magnuson, Jon K.; Menke, Hildegard; Meijer, Martin; Meijer, Susan; Nielsen, Jakob B.; Nielsen, Michael L.; van Ooyen, Albert; Pel, Herman J.; Poulsen, Lars; Samson, Rob; Stam, Hein; Tsang, Adrian; van den Brink, Johannes M.; ATkins, Alex; Aerts, Andrea; Shapiro, Harris; Pangilinan, Jasmyn; Salamov, Asaf; Lou, Yigong; Lindquist, Erika; Lucas, Susan; Grimwood, Jane; Grigoriev, Igor V.; Kubicek, Christian P.; Martinez, Diego; van Peij, Noel; Roubos, Johannes A.; Nielsen, Jens B.; Baker, Scott E.

    2011-06-01

    The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme-producing A. niger strain (CBS 513.88) has already been sequenced, the versatility and diversity of this species compels additional exploration. We therefore undertook whole genome sequencing of the acidogenic A. niger wild type strain (ATCC 1015), and produced a genome sequence of very high quality. Only 15 gaps are present in the sequence and half the telomeric regions have been elucidated. Moreover, sequence information from ATCC 1015 was utilized to improve the genome sequence of CBS 513.88. Chromosome-level comparisons uncovered several genome rearrangements, deletions, a clear case of strain-specific horizontal gene transfer, and identification of 0.8 megabase of novel sequence. Single nucleotide polymorphisms per kilobase (SNPs/kb) between the two strains were found to be exceptionally high (average: 7.8, maximum: 160 SNPs/kb). High variation within the species was confirmed with exo-metabolite profiling and phylogenetics. Detailed lists of alleles were generated, and genotypic differences were observed to accumulate in metabolic pathways essential to acid production and protein synthesis. A transcriptome analysis revealed up-regulation of the electron transport chain, specifically the alternative oxidative pathway in ATCC 1015, while CBS 513.88 showed significant up regulation of genes associated with biosynthesis of amino acids that are abundant in glucoamylase A, tRNA-synthases and protein transporters.

  1. Global mapping of protein phosphorylation events identifies novel signalling hubs mediating fatty acid starvation responses in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Pultz, Dennis; Bennetzen, Martin; Rødkær, Steven Vestergaard;

    2011-01-01

    in a temporal manner in response to inhibition of fatty acid synthesis by cerulenin. By in silico analysis of these phosphorylation events, we have identified the major downstream regulated processes and signalling networks mediating the cellular response to fatty acid starvation. The analysis further...

  2. Polygenic analysis and targeted improvement of the complex trait of high acetic acid tolerance in the yeast Saccharomyces cerevisiae

    NARCIS (Netherlands)

    Meijnen, Jean-Paul; Randazzo, Paola; Foulquié-Moreno, María R; van den Brink, Joost; Vandecruys, Paul; Stojiljkovic, Marija; Dumortier, Françoise; Zalar, Polona; Boekhout, Teun; Gunde-Cimerman, Nina; Kokošar, Janez; Štajdohar, Miha; Curk, Tomaž; Petrovič, Uroš; Thevelein, Johan M

    2016-01-01

    BACKGROUND: Acetic acid is one of the major inhibitors in lignocellulose hydrolysates used for the production of second-generation bioethanol. Although several genes have been identified in laboratory yeast strains that are required for tolerance to acetic acid, the genetic basis of the high acetic

  3. Gluconic acid produced by Gluconacetobacter diazotrophicus Pal5 possesses antimicrobial properties.

    Science.gov (United States)

    Nieto-Peñalver, Carlos G; Savino, María J; Bertini, Elisa V; Sánchez, Leandro A; de Figueroa, Lucía I C

    2014-09-01

    Gluconic acid is produced in large quantities by the endophytic and diazotrophic bacterium Gluconacetobacter diazotrophicus Pal5. This organic acid derives from direct oxidation of glucose by a pyrroloquinoline-quinone-linked glucose dehydrogenase in this plant growth-promoting bacterium. In the present article, evidence is presented showing that gluconic acid is also responsible for the antimicrobial activity of G. diazotrophicus Pal5. The broad antagonistic spectrum includes Gram-positive and -negative bacteria. Eukaryotic microorganisms are more resistant to growth inhibition by this acid. Inhibition by gluconic acid can be modified through the presence of other organic acids. In contrast to other microorganisms, the Quorum Sensing system of G. diazotrophicus Pal5, a regulatory mechanism that plays a key role in several microbe-microbe interactions, is not related to gluconic acid production and the concomitant antagonistic activity.

  4. Gluconic acid: an antifungal agent produced by Pseudomonas species in biological control of take-all.

    Science.gov (United States)

    Kaur, Rajvinder; Macleod, John; Foley, William; Nayudu, Murali

    2006-03-01

    Pseudomonas strain AN5 (Ps. str. AN5), a non-fluorescent Australian bacterial isolate, is an effective biological control (biocontrol) agent of the take-all disease of wheat caused by the fungus Gaeumannomyces graminis var. tritici (Ggt). Ps. str. AN5 controls Ggt by producing an antifungal compound which was purified by thin layer and column chromatography, and identified by NMR and mass spectroscopic analysis to be d-gluconic acid. Commercially bought pure gluconic acid strongly inhibited Ggt. Two different transposon mutants of Ps. str. AN5 which had lost take-all biocontrol did not produce d-gluconic acid. Gluconic acid production was restored, along with take-all biocontrol, when one of these transposon mutants was complemented with the corresponding open reading frame from wild-type genomic DNA. Gluconic acid was detected in the rhizosphere of wheat roots treated with the wild-type Ps. str. AN5, but not in untreated wheat or wheat treated with a transposon mutant strain which had lost biocontrol. The antifungal compounds phenazine-1-carboxylic acid and 2,4-diacetylphloroglucinol, produced by other Pseudomonads and previously shown to be effective in suppressing the take-all disease, were not detected in Ps. str. AN5 extracts. These results suggest that d-gluconic acid is the most significant antifungal agent produced by Ps. str. AN5 in biocontrol of take-all on wheat roots.

  5. Mathematical models for determining metabolic fluxes through the citric acid and the glyoxylate cycles in Saccharomyces cerevisiae by 13C-NMR spectroscopy.

    Science.gov (United States)

    Tran-Dinh, S; Bouet, F; Huynh, Q T; Herve, M

    1996-12-15

    We propose, first, a practical method for studying the isotopic transformation of glutamate or any other metabolite isotopomers in the citric acid and the glyoxylate cycles; second, two mathematical models, one for evaluating the flux through the citric acid cycle and the other for evaluating the flux through the latter coupled to the glyoxylate cycle in yeast. These models are based on the analysis of 13C-NMR spectra of glutamate obtained from Saccharomyces cerevisiae, NCYC strain, fed with 100% enriched [2-13C]acetate. The population of each glutamate isotopomer, the change in intensity of each multiplet component or the enrichment of any glutamate carbon is expressed by a specific analytical equation from which the flux in the citric acid and the glyoxylate cycles can be deduced. The aerobic metabolism of 100% [2-13C]acetate in acetate-grown S. cerevisiae cells was studied as a function of time using 13C-NMR. 1H-NMR and biochemical techniques. The C1 and C6 doublet and singlet of labeled trehalose increase continuously with time indicating that there is no isotopic transformation between trehalose isotopomers even though the corresponding formation rates are different. By contrast, the glutamate C4 singlet increases then decreases with time. The C4 doublet, which is lower than the singlet for t 90 min. A similar observation was made for the C2 resonance singlet and doublet. In addition, the glutamate C2 multiplet consists of only seven instead of nine peaks as in random labeling. These results agree well with our models and demonstrate that, in the presence of acetate, anaplerotic carbon sources involved in the synthesis of acetyl-CoA are negligible in yeast. The flux in the citric acid cycle was deduced from a plot of the C4 area versus incubation time, while the flux within the glyoxylate cycle was determined from the relative intensity of the glutamate C4 doublet and singlet. The fluxes in the citric acid and the glyoxylate cycles were found to be comparable

  6. Enhanced isoprene biosynthesis in Saccharomyces cerevisiae by engineering of the native acetyl-CoA and mevalonic acid pathways with a push-pull-restrain strategy.

    Science.gov (United States)

    Lv, Xiaomei; Xie, Wenping; Lu, Wenqiang; Guo, Fei; Gu, Jiali; Yu, Hongwei; Ye, Lidan

    2014-09-30

    To explore the capacity of isoprene production in Saccharomyces cerevisiae, a rational push-pull-restrain strategy was proposed to engineer the mevalonic acid (MVA) and acetyl-CoA pathways. The strategy can be decomposed into the up-regulation of precursor supply in the acetyl-CoA module and the MVA pathway (push-strategy), increase of the isoprene branch flux (pull-strategy), and down-regulation of the competing pathway (restrain-strategy). Furthermore, to reduce the production cost arising from galactose addition and meanwhile maintain the high expression of Gal promoters, the galactose regulatory network was modulated by Gal80p deletion. Finally, the engineered strain YXM10-ispS-ispS could accumulate up to 37 mg/L isoprene (about 782-fold increase compared to the parental strain) under aerobic conditions with glycerol-sucrose as carbon source. In this way, a new potential platform for isoprene production was established via metabolic engineering of the yeast native pathways.

  7. Caffeic acid production enhancement by engineering a phenylalanine over-producing Escherichia coli strain.

    Science.gov (United States)

    Huang, Qin; Lin, Yuheng; Yan, Yajun

    2013-12-01

    Caffeic acid is a plant-specific phenylpropanoic acid with multiple health-improving effects reported, and its therapeutic derivatives have also been studied throughout the last decade. To meet its market need and achieve high-level production, microbial production of caffeic acid approaches have been developed in metabolically engineered Escherichia coli. In our previous work, we have established the first artificial pathway that realized de novo production of caffeic acid using E. coli endogenous 4-hydroxyphenylacetate 3-hydroxylase (4HP3H). In this work, we exploited the catalytic potential of 4HPA3H in the whole-cell bioconversion study and produced 3.82 g/L (461.12 mg/L/OD) caffeic acid from p-coumaric acid, a direct precursor. We further engineered a phenylalanine over-producer into a tyrosine over-producer and then introduced the artificial pathway. After adjusting the expression strategy and optimizing the inoculants timing, de novo production of caffeic acid reached 766.68 mg/L. Both results from the direct precursor and simple carbon sources represent the highest titers of caffeic acid from microbial production so far.

  8. Design of homo-organic acid producing strains using multi-objective optimization

    DEFF Research Database (Denmark)

    Kim, Tae Yong; Park, Jong Myoung; Kim, Hyun Uk

    2015-01-01

    acids, while maintaining sufficiently high growth rate and minimizing the secretion of undesired byproducts. Homo-productions of acetic, lactic and succinic acids were targeted as examples. Engineered E. coli strains capable of producing homo-acetic and homo-lactic acids could be developed by taking...... this systems approach for the minimal identification of gene knockout targets. Also, failure to predict effective gene knockout targets for the homo-succinic acid production suggests that the multi-objective optimization is useful in assessing the suitability of a microorganism as a host strain......Production of homo-organic acids without byproducts is an important challenge in bioprocess engineering to minimize operation cost for separation processes. In this study, we used multi-objective optimization to design Escherichia coli strains with the goals of maximally producing target organic...

  9. Pretreatment of Dried Distiller Grains with Solubles by Soaking in Aqueous Ammonia and Subsequent Enzymatic/Dilute Acid Hydrolysis to Produce Fermentable Sugars.

    Science.gov (United States)

    Nghiem, Nhuan P; Montanti, Justin; Kim, Tae Hyun

    2016-05-01

    Dried distillers grains with solubles (DDGS), a co-product of corn ethanol production in the dry-grind process, was pretreated by soaking in aqueous ammonia (SAA) using a 15 % w/w NH4OH solution at a solid/liquid ratio of 1:10. The effect of pretreatment on subsequent enzymatic hydrolysis was studied at two temperatures (40 and 60 °C) and four reaction times (6, 12, 24, and 48 h). Highest glucose yield of 91 % theoretical was obtained for the DDGS pretreated at 60 °C and 24 h. The solubilized hemicellulose in the liquid fraction was further hydrolyzed with dilute H2SO4 to generate fermentable monomeric sugars. The conditions of acid hydrolysis included 1 and 4 wt% acid, 60 and 120 °C, and 0.5 and 1 h. Highest yields of xylose and arabinose were obtained at 4 wt% acid, 120 °C, and 1 h. The fermentability of the hydrolysate obtained by enzymatic hydrolysis of the SAA-pretreated DDGS was demonstrated in ethanol fermentation by Saccharomyces cerevisiae. The fermentability of the hydrolysate obtained by consecutive enzymatic and dilute acid hydrolysis was demonstrated using a succinic acid-producing microorganism, strain Escherichia coli AFP184. Under the fermentation conditions, complete utilization of glucose and arabinose was observed, whereas only 47 % of xylose was used. The succinic acid yield was 0.60 g/g total sugar consumed.

  10. Acetic acid removal from corn stover hydrolysate using ethyl acetate and the impact on Saccharomyces cerevisiae bioethanol fermentation.

    Science.gov (United States)

    Aghazadeh, Mahdieh; Ladisch, Michael R; Engelberth, Abigail S

    2016-07-08

    Acetic acid is introduced into cellulose conversion processes as a consequence of composition of lignocellulose feedstocks, causing significant inhibition of adapted, genetically modified and wild-type S. cerevisiae in bioethanol fermentation. While adaptation or modification of yeast may reduce inhibition, the most effective approach is to remove the acetic acid prior to fermentation. This work addresses liquid-liquid extraction of acetic acid from biomass hydrolysate through a pathway that mitigates acetic acid inhibition while avoiding the negative effects of the extractant, which itself may exhibit inhibition. Candidate solvents were selected using simulation results from Aspen Plus™, based on their ability to extract acetic acid which was confirmed by experimentation. All solvents showed varying degrees of toxicity toward yeast, but the relative volatility of ethyl acetate enabled its use as simple vacuum evaporation could reduce small concentrations of aqueous ethyl acetate to minimally inhibitory levels. The toxicity threshold of ethyl acetate, in the presence of acetic acid, was found to be 10 g L(-1) . The fermentation was enhanced by extracting 90% of the acetic acid using ethyl acetate, followed by vacuum evaporation to remove 88% removal of residual ethyl acetate along with 10% of the broth. NRRL Y-1546 yeast was used to demonstrate a 13% increase in concentration, 14% in ethanol specific production rate, and 11% ethanol yield. This study demonstrated that extraction of acetic acid with ethyl acetate followed by evaporative removal of ethyl acetate from the raffinate phase has potential to significantly enhance ethanol fermentation in a corn stover bioethanol facility. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:929-937, 2016.

  11. Malfunctioning of the Iron–Sulfur Cluster Assembly Machinery in Saccharomyces cerevisiae Produces Oxidative Stress via an Iron-Dependent Mechanism, Causing Dysfunction in Respiratory Complexes

    Science.gov (United States)

    Gomez, Mauricio; Pérez-Gallardo, Rocío V.; Sánchez, Luis A.; Díaz-Pérez, Alma L.; Cortés-Rojo, Christian; Meza Carmen, Victor; Saavedra-Molina, Alfredo; Lara-Romero, Javier; Jiménez-Sandoval, Sergio; Rodríguez, Francisco; Rodríguez-Zavala, José S.; Campos-García, Jesús

    2014-01-01

    Biogenesis and recycling of iron–sulfur (Fe–S) clusters play important roles in the iron homeostasis mechanisms involved in mitochondrial function. In Saccharomyces cerevisiae, the Fe–S clusters are assembled into apoproteins by the iron–sulfur cluster machinery (ISC). The aim of the present study was to determine the effects of ISC gene deletion and consequent iron release under oxidative stress conditions on mitochondrial functionality in S. cerevisiae. Reactive oxygen species (ROS) generation, caused by H2O2, menadione, or ethanol, was associated with a loss of iron homeostasis and exacerbated by ISC system dysfunction. ISC mutants showed increased free Fe2+ content, exacerbated by ROS-inducers, causing an increase in ROS, which was decreased by the addition of an iron chelator. Our study suggests that the increment in free Fe2+ associated with ROS generation may have originated from mitochondria, probably Fe–S cluster proteins, under both normal and oxidative stress conditions, suggesting that Fe–S cluster anabolism is affected. Raman spectroscopy analysis and immunoblotting indicated that in mitochondria from SSQ1 and ISA1 mutants, the content of [Fe–S] centers was decreased, as was formation of Rieske protein-dependent supercomplex III2IV2, but this was not observed in the iron-deficient ATX1 and MRS4 mutants. In addition, the activity of complexes II and IV from the electron transport chain (ETC) was impaired or totally abolished in SSQ1 and ISA1 mutants. These results confirm that the ISC system plays important roles in iron homeostasis, ROS stress, and in assembly of supercomplexes III2IV2 and III2IV1, thus affecting the functionality of the respiratory chain. PMID:25356756

  12. Phoma glomerata D14: An Endophytic Fungus from Salvia miltiorrhiza That Produces Salvianolic Acid C.

    Science.gov (United States)

    Li, Xiuqing; Zhai, Xin; Shu, Zhiheng; Dong, Ruifang; Ming, Qianliang; Qin, Luping; Zheng, Chengjian

    2016-07-01

    In recent years, more and more researches focus on endophytic fungi derived from important medicinal plants, which can produce the same bioactive metabolites as their host plants. Salvia miltiorrhiza Bunge is a traditional medicinal plant with versatile pharmacological effects. But the wild plant resource has been in short supply due to the overcollection for bioactive metabolites. Our study was therefore conducted to isolate endophytic fungi from S. miltiorrhiza and get candidate strains that produce the same bioactive compounds as the plant. As a result, an endophyte that produces salvianolic acid C was obtained and identified as Phoma glomerata D14 based on its morphology and internal transcribed spacer analysis. Salvianolic acid C was found present in both the mycelia and fermentation broth. Our study indicates that the endophytic fungus has significant industrial potential to meet the pharmaceutical demands for salvianolic acid C in a cost-effective, easily accessible, and reproducible way.

  13. Mating type and ploidy effect on the β-glucosidase activity and ethanol-producing performance of Saccharomyces cerevisiae with multiple δ-integrated bgl1 gene.

    Science.gov (United States)

    Wang, Jianjun; Ma, Yuanyuan; Zhang, Kun; Yang, Huajun; Liu, Cheng; Zou, Shaolan; Hong, Jiefang; Zhang, Minhua

    2016-08-10

    In order to investigate the effect of mating type and ploidy on enzymatic activity and fermentation performance in yeast with multiple δ-integrated foreign genes, eight ploidy series strains were constructed. The initial haploid strain BGL-a was shown to contain about 19 copies of the bgl1 gene. In rich media containing 2% (w/v) sugar the specific activities of BGL-aα were lower than those of BGL-aa or BGL-αα, which indicates the existence of mating type effects. While the maximum OD660 decreased with rising ploidy, the biomass yield showed no significant difference between the eight strains and the specific activities (expressed as U/mL or U/mg DCW) showed little to no variation. When cellobiose was used as the carbon source and β-glucosidase substrate, β-glucosidase was expressed more quickly and at higher levels than in glucose-containing media. The maximum specific activitiy values obtained were 19.07U/mL and 19.39U/mL for BGL-αα and BGL-aa, repsectively. The anaerobic biomass and ethanol-producing performance in rich media containing 10% cellobiose showed no significant difference among the eight strains. Their maximal ethanol concentrations and corresponding yields ranged from 40.27 to 43.46g/L and 77.56 to 83.71%, respectively. When the acid- and alkali-pretreated corncob (10% solids content) was used, the diploid BGL-aα fermented the best. When urea was used as the only supplemented nutrient, the ethanol titer and yield were 35.65g/L and 83.69%, respectively, while a control experiment using industrial Angel yeast with exogenous β-glucosidase addition gave values of 37.93g/L and 89.04%. The combined effects of δ-integration of bgl1, ploidy and mating type result in BGL-aa or BGL-αα being the optimal choice for enzyme production and BGL-aα being more suitable for cellulosic ethanol fermentation. These results provide valuable information for future yeast breeding and utilization efforts.

  14. ISOLATION AND IDENTIFICATION OF LACTIC ACID PRODUCING BACTERIA FROM CAMEL MILK

    OpenAIRE

    Toqeer Ahmad, Rashida Kanwal, Izhar Hussain Athar1, Najam Ayub

    2002-01-01

    Lactic acid bacteria (LAB) were isolated from camel milk by culturing the camel milk on specific media and pure culture was obtained by sub culturing. Purification of culture was confirmed by Gram's staining and identified by different bio-chemical tests. Camel milk contains lactic acid producing bacteria including Strpptococci such as S. cremoris and S. lactis and Lactobacilli such as L. acidophilus L. acidophilus grows more rapidly in camel milk than others as its growth is supported by cam...

  15. Selection of Anodic Material Used in Electrolytic Process for Producing Hypophosphorous Acid

    Institute of Scientific and Technical Information of China (English)

    Fu Sheng WANG; Bing Kui SONG; Xiao Li HAN; Bao Gui ZHANG

    2004-01-01

    Black lead, Ti-Ru and Ti-PbO2 were used as anode and stainless steel was used as cathode.The electrolytic process of producing hypophosphorous acid with four-compartment electrodialytic cell was studied. The comparison of some factors, such as anodic voltage, product concentration and current efficiency, of black lead, Ti-Ru, and Ti-PbO2 electrodes was conducted. As a result, the Ti-PbO2 electrode is the optimal anode material used, it can be in electrolytic process for producing hypophosphorous acid.

  16. Diverse bacterial PKS sequences derived from okadaic acid-producing dinoflagellates.

    Science.gov (United States)

    Perez, Roberto; Liu, Li; Lopez, Jose; An, Tianying; Rein, Kathleen S

    2008-05-22

    Okadaic acid (OA) and the related dinophysistoxins are isolated from dinoflagellates of the genus Prorocentrum and Dinophysis. Bacteria of the Roseobacter group have been associated with okadaic acid producing dinoflagellates and have been previously implicated in OA production. Analysis of 16S rRNA libraries reveals that Roseobacter are the most abundant bacteria associated with OA producing dinoflagellates of the genus Prorocentrum and are not found in association with non-toxic dinoflagellates. While some polyketide synthase (PKS) genes form a highly supported Prorocentrum clade, most appear to be bacterial, but unrelated to Roseobacter or Alpha-Proteobacterial PKSs or those derived from other Alveolates Karenia brevis or Crytosporidium parvum.

  17. Evaluation of Acid Producing Potential of Road-cut Rock Slopes

    Science.gov (United States)

    Min, K.; Han, D.

    2006-12-01

    Acid rock drainage (ARD) developed as a result of road construction represents a number of technical, environmental, and social problems. Engineering impacts from ARD, the product of atmospheric oxidation of rock-forming sulfide minerals, including degradation of surface water quality, disintegration of construction materials, and structural damage of buildings, have been documented widely around the world. To characterize the ARD and to evaluate acid producing potential of road-cut rocks, samples of rocks and water were collected from two road-cut sites of shale to phyllite showing such visual indicators of ARD as orange iron precipitates along streambed and rocks. Acid Base Accounting (ABA) test, the most commonly applied static test to evaluate the potential acidity, and X-ray diffraction (XRD) analysis were performed for fifteen rock samples. In terms of NAPP (Net Acid Producing Potential) and NAGpH (pH of Net Acid Generation), seven, four, and four rock samples were classified into a PAF (potentially acid forming) group, a NAF (non-acid forming) group, and an uncertain group, respectively. Water samples with low pH of 4.4, low DO (dissolved oxygen), and high contents of heavy metals and sulfate ion showed the generation of ARD in the studied area, which confirmed the applicability of ABA test to prediction of ARD in road-cut rock slopes. Evaluation of acid producing potential of earth materials should be an essential step in the pre-design stage of construction works especially in the vicinity of mining areas.

  18. Generation of fad2 transgenic mice that produce omega-6 fatty acids

    Institute of Scientific and Technical Information of China (English)

    CHEN Qing; LIU Qing; WU ZhiFang; WANG ZongYi; GOU KeMian

    2009-01-01

    Fatty acid desaturase-2 (FAD2)introduces a double bond in position △12 in oleic acid (18:1)to form linoleic acid (18:2 n-6)in higher plants and microbes.A new transgenic expression cassette,containing CMV promoter/fad2 cDNA/SV40 polyA,was constructedto produce transgenic mice.Among 63 healthy offspring,10 founders (15.9%)integrated the cotton fad2 transgene into their genomes,as demonstrated by PCR and Southern blotting analysis.All founder mice were fertile and heterozygous fad2 female and nontransgenic littermates were used for fatty acid analysis using gas chromatography.One fad2 transgenic line showed substantial differences in the fatty acid profiles and the level of linoleic acid was increased 19% (P<0.05)in transgenic muscles compared to their nontransgenic littermates.Moreover,it exhibited an 87% and a 9% increase (P<0.05)in arachidonic acid (20:4 n-6)in muscles and liver,compared to their nontransgenic littermates.The results indicate that the plant fad2 gene can be functionally expressed in transgenic mice and may playan active role in conversion of oleic acid into linoleic acid.

  19. Generation of fad2 transgenic mice that produce omega-6 fatty acids

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Fatty acid desaturase-2 (FAD2) introduces a double bond in position 12 in oleic acid (18:1) to form linoleic acid (18:2 n-6) in higher plants and microbes. A new transgenic expression cassette, containing CMV promoter/fad2 cDNA/SV40 polyA, was constructedto produce transgenic mice. Among 63 healthy offspring, 10 founders (15.9%) integrated the cotton fad2 transgene into their genomes, as demonstrated by PCR and Southern blotting analysis. All founder mice were fertile and heterozygous fad2 female and nontransgenic littermates were used for fatty acid analysis using gas chromatography. One fad2 transgenic line showed substantial differences in the fatty acid profiles and the level of linoleic acid was increased 19% (P<0.05) in transgenic muscles compared to their nontransgenic littermates. Moreover, it exhibited an 87% and a 9% increase (P<0.05) in arachidonic acid (20:4 n-6) in muscles and liver, compared to their nontransgenic littermates. The results indicate that the plant fad2 gene can be functionally expressed in transgenic mice and may playan active role in conversion of oleic acid into linoleic acid.

  20. Diversity of Heteropolysaccharide-Producing Lactic Acid Bacterium Strains and Their Biopolymers

    Science.gov (United States)

    Mozzi, Fernanda; Vaningelgem, Frederik; Hébert, Elvira María; Van der Meulen, Roel; Foulquié Moreno, María Remedios; Font de Valdez, Graciela; De Vuyst, Luc

    2006-01-01

    Thirty-one lactic acid bacterial strains from different species were evaluated for exopolysaccharide (EPS) production in milk. Thermophilic strains produced more EPS than mesophilic ones, but EPS yields were generally low. Ropiness or capsular polysaccharide formation was strain dependent. Six strains produced high-molecular-mass EPS. Polymers were classified into nine groups on the basis of their monomer composition. EPS from Enterococcus strains were isolated and characterized. PMID:16751563

  1. Screening of marine bacterial producers of polyunsaturated fatty acids and optimisation of production.

    Science.gov (United States)

    Abd El Razak, Ahmed; Ward, Alan C; Glassey, Jarka

    2014-02-01

    Water samples from three different environments including Mid Atlantic Ridge, Red Sea and Mediterranean Sea were screened in order to isolate new polyunsaturated fatty acids (PUFAs) bacterial producers especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Two hundred and fifty-one isolates were screened for PUFA production and among them the highest number of producers was isolated from the Mid-Atlantic Ridge followed by the Red Sea while no producers were found in the Mediterranean Sea samples. The screening strategy included a simple colourimetric method followed by a confirmation via GC/MS. Among the tested producers, an isolate named 66 was found to be a potentially high PUFA producer producing relatively high levels of EPA in particular. A Plackett-Burman statistical design of experiments was applied to screen a wide number of media components identifying glycerol and whey as components of a production medium. The potential low-cost production medium was optimised by applying a response surface methodology to obtain the highest productivity converting industrial by-products into value-added products. The maximum achieved productivity of EPA was 20 mg/g, 45 mg/l, representing 11% of the total fatty acids, which is approximately five times more than the amount produced prior to optimisation. The production medium composition was 10.79 g/l whey and 6.87 g/l glycerol. To our knowledge, this is the first investigation of potential bacteria PUFA producers from Mediterranean and Red Seas providing an evaluation of a colourimetric screening method as means of rapid screening of a large number of isolates.

  2. Physiological characterization of the high malic acid-producing Aspergillus oryzae strain 2103a-68.

    Science.gov (United States)

    Knuf, Christoph; Nookaew, Intawat; Remmers, Ilse; Khoomrung, Sakda; Brown, Stephen; Berry, Alan; Nielsen, Jens

    2014-04-01

    Malic acid is a C₄ dicarboxylic acid that is currently mainly used in the food and beverages industry as an acidulant. Because of the versatility of the group of C₄ dicarboxylic acids, the chemical industry has a growing interest in this chemical compound. As malic acid will be considered as a bulk chemical, microbial production requires organisms that sustain high rates, yields, and titers. Aspergillus oryzae is mainly known as an industrial enzyme producer, but it was also shown that it has a very competitive natural production capacity for malic acid. Recently, an engineered A. oryzae strain, 2103a-68, was presented which overexpressed pyruvate carboxylase, malate dehydrogenase, and a malic acid transporter. In this work, we report a detailed characterization of this strain including detailed rates and yields under malic acid production conditions. Furthermore, transcript levels of the genes of interest and corresponding enzyme activities were measured. On glucose as carbon source, 2103a-68 was able to secrete malic acid at a maximum specific production rate during stationary phase of 1.87 mmol (g dry weight (DW))⁻¹ h⁻¹ and with a yield of 1.49 mol mol⁻¹. Intracellular fluxes were obtained using ¹³C flux analysis during exponential growth, supporting the success of the metabolic engineering strategy of increasing flux through the reductive cytosolic tricarboxylic acid (rTCA) branch. Additional cultivations using xylose and a glucose/xylose mixture demonstrated that A. oryzae is able to efficiently metabolize pentoses and hexoses to produce malic acid at high titers, rates, and yields.

  3. Comparative genomics of citric-acid producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88

    Energy Technology Data Exchange (ETDEWEB)

    Grigoriev, Igor V.; Baker, Scott E.; Andersen, Mikael R.; Salazar, Margarita P.; Schaap, Peter J.; Vondervoot, Peter J.I. van de; Culley, David; Thykaer, Jette; Frisvad, Jens C.; Nielsen, Kristen F.; Albang, Richard; Albermann, Kaj; Berka, Randy M.; Braus, Gerhard H.; Braus-Stromeyer, Susanna A.; Corrochano, Luis M.; Dai, Ziyu; Dijck, Piet W.M. van; Hofmann, Gerald; Lasure, Linda L.; Magnusson, Jon K.; Meijer, Susan L.; Nielsen, Jakob B.; Nielsen, Michael L.; Ooyen, Albert J.J. van; Panther, Kathyrn S.; Pel, Herman J.; Poulsen, Lars; Samson, Rob A.; Stam, Hen; Tsang, Adrian; Brink, Johannes M. van den; Atkins, Alex; Aerts, Andrea; Shapiro, Harris; Pangilinan, Jasmyn; Salamov, Asaf; Lou, Yigong; Lindquist, Erika; Lucas, Susan; Grimwood, Jane; Kubicek, Christian P.; Martinez, Diego; Peij, Noel N.M.E. van; Roubos, Johannes A.; Nielsen, Jens

    2011-04-28

    The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme-producing A. niger strain (CBS 513.88) has already been sequenced, the versatility and diversity of this species compels additional exploration. We therefore undertook whole genome sequencing of the acidogenic A. niger wild type strain (ATCC 1015), and produced a genome sequence of very high quality. Only 15 gaps are present in the sequence and half the telomeric regions have been elucidated. Moreover, sequence information from ATCC 1015 was utilized to improve the genome sequence of CBS 513.88. Chromosome-level comparisons uncovered several genome rearrangements, deletions, a clear case of strain-specific horizontal gene transfer, and identification of 0.8 megabase of novel sequence. Single nucleotide polymorphisms per kilobase (SNPs/kb) between the two strains were found to be exceptionally high (average: 7.8, maximum: 160 SNPs/kb). High variation within the species was confirmed with exo-metabolite profiling and phylogenetics. Detailed lists of alleles were generated, and genotypic differences were observed to accumulate in metabolic pathways essential to acid production and protein synthesis. A transcriptome analysis revealed up-regulation of the electron transport chain, specifically the alternative oxidative pathway in ATCC 1015, while CBS 513.88 showed significant up-regulation of genes relevant to glucoamylase A production, such as tRNA-synthases and protein transporters. Our results and datasets from this integrative systems biology analysis resulted in a snapshot of fungal evolution and will support further optimization of cell factories based on filamentous fungi.[Supplemental materials (10 figures, three text documents and 16 tables) have been made available

  4. Microbiologically produced carboxylic acids used as building blocks in organic synthesis.

    Science.gov (United States)

    Aurich, Andreas; Specht, Robert; Müller, Roland A; Stottmeister, Ulrich; Yovkova, Venelina; Otto, Christina; Holz, Martina; Barth, Gerold; Heretsch, Philipp; Thomas, Franziska A; Sicker, Dieter; Giannis, Athanassios

    2012-01-01

    Oxo- and hydroxy-carboxylic acids are of special interest in organic synthesis. However, their introduction by chemical reactions tends to be troublesome especially with regard to stereoselectivity. We describe herein the biotechnological preparation of selected oxo- and hydroxycarboxylic acids under "green" conditions and their use as promising new building blocks. Thereby, our biotechnological goal was the development of process fundamentals regarding the variable use of renewable raw materials, the development of a multi purpose bioreactor and application of a pilot plant with standard equipment for organic acid production to minimize the technological effort. Furthermore the development of new product isolation procedures, with the aim of direct product recovery, capture of products or single step operation, was necessary. The application of robust and approved microorganisms, also genetically modified, capable of using a wide range of substrates as well as producing a large spectrum of products, was of special importance. Microbiologically produced acids, like 2-oxo-glutaric acid and 2-oxo-D-gluconic acid, are useful educts for the chemical synthesis of hydrophilic triazines, spiro-connected heterocycles, benzotriazines, and pyranoic amino acids. The chiral intermediate of the tricarboxylic acid cycle, (2R,3S)-isocitric acid, is another promising compound. For the first time our process provides large quantities of enantiopure trimethyl (2R,3S)-isocitrate which was used in subsequent chemical transformations to provide new chiral entities for further usage in total synthesis and pharmaceutical research.Oxo- and hydroxy-carboxylic acids are of special interest in organic synthesis. However, their introduction by chemical reactions tends to be troublesome especially with regard to stereoselectivity. We describe herein the biotechnological preparation of selected oxo- and hydroxycarboxylic acids under "green" conditions and their use as promising new building

  5. Electrocatalytic oxidation of n-propanol to produce propionic acid using an electrocatalytic membrane reactor.

    Science.gov (United States)

    Li, Jiao; Li, Jianxin; Wang, Hong; Cheng, Bowen; He, Benqiao; Yan, Feng; Yang, Yang; Guo, Wenshan; Ngo, Huu Hao

    2013-05-18

    An electrocatalytic membrane reactor assembled using a nano-MnO2 loading microporous Ti membrane as an anode and a tubular stainless steel as a cathode was used to oxidize n-propanol to produce propionic acid. The high efficiency and selectivity obtained is related to the synergistic effect between the reaction and separation in the reactor.

  6. Modification of wheat gluten with citric acid to produce superabsorbent materials

    Science.gov (United States)

    Wheat gluten was reacted with citric acid to produce natural superabsorbent materials able to absorb up to 78 times its weight in water. The properties of the modified gluten samples were characterized using Fourier Transform Infra-red (FTIR) spectroscopy, thermogravimetric analysis, and water uptak...

  7. Glucansucrases from lactic acid bacteria which produce water-insoluble polysaccharides from sucrose

    Science.gov (United States)

    Dextrans and related glucans produced from sucrose by lactic acid bacteria have been studied for many years and are used in numerous commercial applications and products. Most of these glucans are water-soluble, except for a few notable exceptions from cariogenic Streptococcus spp. and a very small ...

  8. Draft Genome Sequence of the Butyric Acid Producer Clostridium tyrobutyricum Strain CIP I-776 (IFP923).

    Science.gov (United States)

    Wasels, François; Clément, Benjamin; Lopes Ferreira, Nicolas

    2016-03-03

    Here, we report the draft genome sequence of Clostridium tyrobutyricum CIP I-776 (IFP923), an efficient producer of butyric acid. The genome consists of a single chromosome of 3.19 Mb and provides useful data concerning the metabolic capacities of the strain.

  9. Draft Genome Sequence of the Butyric Acid Producer Clostridium tyrobutyricum Strain CIP I-776 (IFP923)

    OpenAIRE

    2016-01-01

    Here, we report the draft genome sequence of Clostridium tyrobutyricum CIP I-776 (IFP923), an efficient producer of butyric acid. The genome consists of a single chromosome of 3.19 Mb and provides useful data concerning the metabolic capacities of the strain.

  10. Draft Genome Sequence of Sorghum Grain Mold Fungus Epicoccum sorghinum, a Producer of Tenuazonic Acid

    Science.gov (United States)

    Oliveira, Rodrigo C.; Davenport, Karen W.; Hovde, Blake; Silva, Danielle; Chain, Patrick S. G.; Correa, Benedito

    2017-01-01

    ABSTRACT The facultative plant pathogen Epicoccum sorghinum is associated with grain mold of sorghum and produces the mycotoxin tenuazonic acid. This fungus can have serious economic impact on sorghum production. Here, we report the draft genome sequence of E. sorghinum (USPMTOX48). PMID:28126937

  11. Modification of vital wheat gluten with phosphoric acid to produce high free-solution capacity

    Science.gov (United States)

    Wheat gluten reacts with phosphoric acid to produce natural superabsorbent gels. The gel properties are defined by Fourier Transform Infra-red (FTIR) spectroscopy, 2-dimensional gel electrophoresis (2DE), and uptake of water, salt solutions, and aqueous ethanol. Temperatures above 120'C and dry cond...

  12. Modification of vital wheat gluten with phosphoric acid to produce high free solution capacity

    Science.gov (United States)

    Wheat gluten reacts with phosphoric acid in the presence of urea to produce natural superabsorbent gels. Fourier Transform Infra-red (FT-IR) spectroscopy and two-dimensional gel electrophoresis (2DE) reveal chemical changes from the reaction. Temperatures above 120°C and dry conditions create the op...

  13. Engineering and systems level analysis of Saccharomyces cerevisiae for production of 3 hydroxypropionic acid via malonyl CoA reductase dependent pathway

    DEFF Research Database (Denmark)

    Kildegaard, Kanchana Rueksomtawin; Jensen, Niels Bjerg; Schneider, Konstantin;

    2016-01-01

    In the future, oil- and gas-derived polymers may be replaced with bio-based polymers, produced from renewable feedstocks using engineered cell factories. Acrylic acid and acrylic esters with an estimated world annual production of approximately 6 million tons by 2017 can be derived from 3...

  14. Transcriptome-Based Characterization of Interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus in Lactose-Grown Chemostat Cocultures

    NARCIS (Netherlands)

    Mendes, F.; Sieuwerts, S.; De Hulster, E.; Almering, M.J.; Luttik, M.A.; Pronk, J.T.; Smid, E.J.; Bron, P.A.; Daran-Lapujade, P.

    2013-01-01

    Mixed populations of Saccharomyces cerevisiae yeasts and lactic acid bacteria occur in many dairy, food, and beverage fermentations, but knowledge about their interactions is incomplete. In the present study, interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaric

  15. Transcriptome-based characterization of interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus in lactose-grown chemostat cocultures

    NARCIS (Netherlands)

    Mendes, F.; Sieuwerts, S.; Hulster, de E.; Almering, M.J.; Luttik, M.A.H.; Pronk, J.T.; Smid, E.J.; Baron, P.A.; Daran-Lapujade, P.

    2013-01-01

    Mixed populations of Saccharomyces cerevisiae yeasts and lactic acid bacteria occur in many dairy, food, and beverage fermentations, but knowledge about their interactions is incomplete. In the present study, interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaric

  16. Usefulness of Organic Acid Produced by Exiguobacterium sp. 12/1 on Neutralization of Alkaline Wastewater

    Directory of Open Access Journals (Sweden)

    Niha Mohan Kulshreshtha

    2012-01-01

    Full Text Available The aim of this study was to investigate the role of organic acids produced by Exiguobacterium sp. strain 12/1 (DSM 21148 in neutralization of alkaline wastewater emanated from beverage industry. This bacterium is known to be able to grow in medium of pH as high as pH 12.0 and to neutralize alkaline industrial wastewater from pH 12.0 to pH 7.5. The initial investigation on the type of functional groups present in medium, carried out using FT-IR spectroscopy, revealed the presence of peaks corresponding to carbonyl group and hydroxyl group, suggesting the release of carboxylic acid or related metabolic product(s. The identification of specific carboxylic group, carried out using RP-HPLC, revealed the presence of a single peak in the culture supernatant with retention time most similar to formic acid. The concentration of acid produced on different carbon sources was studied as a function of time. Although acid was present in same final concentration, the rate of acid production was highest in case of medium supplemented with sucrose followed by fructose and glucose. The knowledge of metabolic products of the bacterium can be considered as a first step towards realization of its potential for large-scale bioremediation of alkaline wastewater from beverage industry.

  17. Plant Hormone Salicylic Acid Produced by a Malaria Parasite Controls Host Immunity and Cerebral Malaria Outcome.

    Science.gov (United States)

    Matsubara, Ryuma; Aonuma, Hiroka; Kojima, Mikiko; Tahara, Michiru; Andrabi, Syed Bilal Ahmad; Sakakibara, Hitoshi; Nagamune, Kisaburo

    2015-01-01

    The apicomplexan parasite Toxoplasma gondii produces the plant hormone abscisic acid, but it is unclear if phytohormones are produced by the malaria parasite Plasmodium spp., the most important parasite of this phylum. Here, we report detection of salicylic acid, an immune-related phytohormone of land plants, in P. berghei ANKA and T. gondii cell lysates. However, addition of salicylic acid to P. falciparum and T. gondii culture had no effect. We transfected P. falciparum 3D7 with the nahG gene, which encodes a salicylic acid-degrading enzyme isolated from plant-infecting Pseudomonas sp., and established a salicylic acid-deficient mutant. The mutant had a significantly decreased concentration of parasite-synthesized prostaglandin E2, which potentially modulates host immunity as an adaptive evolution of Plasmodium spp. To investigate the function of salicylic acid and prostaglandin E2 on host immunity, we established P. berghei ANKA mutants expressing nahG. C57BL/6 mice infected with nahG transfectants developed enhanced cerebral malaria, as assessed by Evans blue leakage and brain histological observation. The nahG-transfectant also significantly increased the mortality rate of mice. Prostaglandin E2 reduced the brain symptoms by induction of T helper-2 cytokines. As expected, T helper-1 cytokines including interferon-γ and interleukin-2 were significantly elevated by infection with the nahG transfectant. Thus, salicylic acid of Plasmodium spp. may be a new pathogenic factor of this threatening parasite and may modulate immune function via parasite-produced prostaglandin E2.

  18. Plant Hormone Salicylic Acid Produced by a Malaria Parasite Controls Host Immunity and Cerebral Malaria Outcome.

    Directory of Open Access Journals (Sweden)

    Ryuma Matsubara

    Full Text Available The apicomplexan parasite Toxoplasma gondii produces the plant hormone abscisic acid, but it is unclear if phytohormones are produced by the malaria parasite Plasmodium spp., the most important parasite of this phylum. Here, we report detection of salicylic acid, an immune-related phytohormone of land plants, in P. berghei ANKA and T. gondii cell lysates. However, addition of salicylic acid to P. falciparum and T. gondii culture had no effect. We transfected P. falciparum 3D7 with the nahG gene, which encodes a salicylic acid-degrading enzyme isolated from plant-infecting Pseudomonas sp., and established a salicylic acid-deficient mutant. The mutant had a significantly decreased concentration of parasite-synthesized prostaglandin E2, which potentially modulates host immunity as an adaptive evolution of Plasmodium spp. To investigate the function of salicylic acid and prostaglandin E2 on host immunity, we established P. berghei ANKA mutants expressing nahG. C57BL/6 mice infected with nahG transfectants developed enhanced cerebral malaria, as assessed by Evans blue leakage and brain histological observation. The nahG-transfectant also significantly increased the mortality rate of mice. Prostaglandin E2 reduced the brain symptoms by induction of T helper-2 cytokines. As expected, T helper-1 cytokines including interferon-γ and interleukin-2 were significantly elevated by infection with the nahG transfectant. Thus, salicylic acid of Plasmodium spp. may be a new pathogenic factor of this threatening parasite and may modulate immune function via parasite-produced prostaglandin E2.

  19. Amino acid residues involved in ligand preference of the Snf3 transporter-like sensor in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Dietvorst, J.; Karhumaa, Kaisa; Kielland-Brandt, Morten;

    2010-01-01

    -methylglucoside and 6-deoxyglucose. The signalling proficiency of a non-phosphorylatable analogue strongly supports the notion that sensing through Snf3 does not require sugar phosphorylation. Sequence comparisons of Snf3 to glucose transporters indicated amino acid residues possibly involved in sensing of sugars other...... than glucose. By site-specific mutagenesis of the structural gene, roles of specific residues in Snf3 could he established. Change of isoleucine-374 to valine ill transmembrane segment 7 of Snf3 partially abolished sensing of fructose mannose. while mutagenesis causing it change of phenylalanine-462 (4......) tyrosine ill transmembrane segment 10 of Snf3 abolished sensing of fructose. Neither of these amino :kill changes affected the ability of Snf3 to sense glucose, nor did they permit Snf3 to sense galactose. These data indicate it similarity between it ligand binding site of the sensor Snf3 and binding sites...

  20. Oxidative stability of structured lipids produced from sunflower oil and caprylic acid

    DEFF Research Database (Denmark)

    Timm Heinrich, Maike; Xu, Xuebing; Nielsen, Nina Skall;

    2003-01-01

    a commercial antioxidant blend Grindox 117 (propyl gallate/citric acid/ascorbyl palmitate) or gallic acid to the SL was investigated. The lipid type affected the oxidative stability: SL was less stable than SO and RL. The reduced stability was most likely caused by both the structure of the lipid......Traditional sunflower oil (SO), randomized lipid (RL) and specific structured lipid (SL), both produced from SO and tricaprylin/caprylic acid, respectively, were stored for up to 12 wk to compare their oxidative stabilities by chemical and sensory analyses. Furthermore, the effect of adding...... and differences in production/purification, which caused lower tocopherol content and higher initial levels of primary and secondary oxidation products in SL compared with RL and SO. Grindox 117 and gallic acid did not exert a distinct antioxidative effect in the SL oil samples during storage...

  1. Novel technologies provide more engineering strategies for amino acid-producing microorganisms.

    Science.gov (United States)

    Gu, Pengfei; Su, Tianyuan; Qi, Qingsheng

    2016-03-01

    Traditionally, amino acid-producing strains were obtained by random mutagenesis and subsequent selection. With the development of genetic and metabolic engineering techniques, various microorganisms with high amino acid production yields are now constructed by rational design of targeted biosynthetic pathways. Recently, novel technologies derived from systems and synthetic biology have emerged and open a new promising avenue towards the engineering of amino acid production microorganisms. In this review, these approaches, including rational engineering of rate-limiting enzymes, real-time sensing of end-products, pathway optimization on the chromosome, transcription factor-mediated strain improvement, and metabolic modeling and flux analysis, were summarized with regard to their application in microbial amino acid production.

  2. Investigation of secondary formation of formic acid: urban environment vs. oil and gas producing region

    Science.gov (United States)

    Yuan, B.; Veres, P. R.; Warneke, C.; Roberts, J. M.; Gilman, J. B.; Koss, A.; Edwards, P. M.; Graus, M.; Kuster, W. C.; Li, S.-M.; Wild, R. J.; Brown, S. S.; Dubé, W. P.; Lerner, B. M.; Williams, E. J.; Johnson, J. E.; Quinn, P. K.; Bates, T. S.; Lefer, B.; Hayes, P. L.; Jimenez, J. L.; Weber, R. J.; Zamora, R.; Ervens, B.; Millet, D. B.; Rappenglück, B.; de Gouw, J. A.

    2015-02-01

    Formic acid (HCOOH) is one of the most abundant carboxylic acids in the atmosphere. However, current photochemical models cannot fully explain observed concentrations and in particular secondary formation of formic acid across various environments. In this work, formic acid measurements made at an urban receptor site (Pasadena) in June-July 2010 during CalNex (California Research at the Nexus of Air Quality and Climate Change) and a site in an oil and gas producing region (Uintah Basin) in January-February 2013 during UBWOS 2013 (Uintah Basin Winter Ozone Studies) will be discussed. Although the VOC (volatile organic compounds) compositions differed dramatically at the two sites, measured formic acid concentrations were comparable: 2.3 ± 1.3 in UBWOS 2013 and 2.0 ± 1.0 ppb in CalNex. We determine that concentrations of formic acid at both sites were dominated by secondary formation (> 99%). A constrained box model using the Master Chemical Mechanism (MCM v3.2) underestimates the measured formic acid concentrations drastically at both sites (by a factor of > 10). Compared to the original MCM model that includes only ozonolysis of unsaturated organic compounds and OH oxidation of acetylene, when we updated yields of ozonolysis of alkenes and included OH oxidation of isoprene, vinyl alcohol chemistry, reaction of formaldehyde with HO2, oxidation of aromatics, and reaction of CH3O2 with OH, the model predictions for formic acid were improved by a factor of 6.4 in UBWOS 2013 and 4.5 in CalNex, respectively. A comparison of measured and modeled HCOOH/acetone ratios is used to evaluate the model performance for formic acid. We conclude that the modified chemical mechanism can explain 19 and 45% of secondary formation of formic acid in UBWOS 2013 and CalNex, respectively. The contributions from aqueous reactions in aerosol and heterogeneous reactions on aerosol surface to formic acid are estimated to be 0-6 and 0-5% in UBWOS 2013 and CalNex, respectively. We observe that

  3. Ascorbic acid administration produces an antidepressant-like effect: evidence for the involvement of monoaminergic neurotransmission.

    Science.gov (United States)

    Binfaré, Ricardo W; Rosa, Angelo O; Lobato, Kelly R; Santos, Adair R S; Rodrigues, Ana Lúcia S

    2009-04-30

    Ascorbic acid is highly concentrated in the brain, being considered as a neuromodulator. This study investigated the effect of ascorbic acid in the tail suspension test (TST) and in the forced swimming test (FST) in mice and the contribution of the monoaminergic system to its antidepressant-like effect. Moreover, the effects of fluoxetine, imipramine and bupropion in combination with ascorbic acid in the TST were investigated. Ascorbic acid (0.1-10 mg/kg, i.p., 1-10 mg/kg p.o. or 0.1 nmol/mice i.c.v.) produced an antidepressant-like effect in the TST, but not in the FST, without altering the locomotor activity. The effect of ascorbic acid (0.1 mg/kg, i.p.) in the TST was prevented by i.p. pre-treatment with NAN-190 (0.5 mg/kg), ketanserin (5 mg/kg), MDL72222 (0.1 mg/kg), prazosin (62.5 microg/kg), yohimbine (1 mg/kg), propranolol (2 mg/kg), haloperidol (0.2 mg/kg), sulpiride (50 mg/kg), but not with SCH23390 (0.05 mg/kg, s.c.). Additionally, ascorbic acid (1 mg/kg, p.o.) potentiated the effect of subeffective doses (p.o. route) of fluoxetine (1 mg/kg), imipramine (0.1 mg/kg), or bupropion (1 mg/kg) in the TST. The combined treatment of ascorbic acid with antidepressants produced no alteration in the locomotion in the open-field test. In conclusion, our results show that administration of ascorbic acid produces an antidepressant-like effect in TST, which is dependent on its interaction with the monoaminergic system. Moreover, ascorbic acid caused a synergistic antidepressant-like effect with conventional antidepressants. Therefore, the present findings warrant further studies to evaluate the therapeutical relevance of ascorbic acid for the treatment of depression and as a co-adjuvant treatment with antidepressants.

  4. Is it possible to produce succinic acid at a low pH?

    Science.gov (United States)

    Yuzbashev, Tigran V; Yuzbasheva, Evgeniya Y; Laptev, Ivan A; Sobolevskaya, Tatiana I; Vybornaya, Tatiana V; Larina, Anna S; Gvilava, Ilia T; Antonova, Svetlana V; Sineoky, Sergey P

    2011-01-01

    Bio-based succinate is still a matter of special emphasis in biotechnology and adjacent research areas. The vast majority of natural and engineered producers are bacterial strains that accumulate succinate under anaerobic conditions. Recently, we succeeded in obtaining an aerobic yeast strain capable of producing succinic acid at low pH. Herein, we discuss some difficulties and advantages of microbial pathways producing "succinic acid" rather than "succinate." It was concluded that the peculiar properties of the constructed yeast strain could be clarified in view of a distorted energy balance. There is evidence that in an acidic environment, the majority of the cellular energy available as ATP will be spent for proton and anion efflux. The decreased ATP:ADP ratio could essentially reduce the growth rate or even completely inhibit growth. In the same way, the preference of this elaborated strain for certain carbon sources could be explained in terms of energy balance. Nevertheless, the opportunity to exclude alkali and mineral acid waste from microbial succinate production seems environmentally friendly and cost-effective.

  5. COMPARATIVE ANALYSIS OF OXALIC ACID PRODUCED FROM RICE HUSK AND PADDY

    Directory of Open Access Journals (Sweden)

    P.I. Oghome

    2012-09-01

    Full Text Available In this research work, comparative analysis of Oxalic acid produced from Rice husk and Paddy was carried out in order to ascertain which waste sample produced a better yield. Nitric acid oxidation of carbohydrates was the method adopted in the production. The variable ratios of HNO3:H2SO4 used were 80:20, 70:30, 60:40, and 50:50. The variable ratio of 60:40 gave the maximum yield and at a maximum temperature of 75oC. Rice husk sample gave a percentage yield of 53.2, 64.4, 81.0, and 53.3 at temperatures of 55 oC, 65 oC, 75 oC, and 85 oC respectively. In the case of paddy a percentage yield of 53.1, 64.0, 79.9, and 52.8 at temperatures of 55 oC, 65 oC, 75 oC, and 85 oC were obtained respectively. The plots between yield and temperature at different variable ratios illustrate the dependence of yield on temperature, which was similar to a parabolic relationship and the peak value (yield was at 75 oC above which it decreased. The properties of oxalic acid from both sources were very close and compared favourably with literature. In comparing the yield, oxalic acid produced from Rice husk gave higher yield than that from Paddy.

  6. Morphological changes produced by acid dissolution in Er:YAG laser irradiated dental enamel.

    Science.gov (United States)

    Manuela Díaz-Monroy, Jennifer; Contreras-Bulnes, Rosalía; Fernando Olea-Mejía, Oscar; Emma Rodríguez-Vilchis, Laura; Sanchez-Flores, Ignacio

    2014-06-01

    Several scientific reports have shown the effects of Er:YAG laser irradiation on enamel morphology. However, there is lack of information regarding the morphological alterations produced by the acid attack on the irradiated surfaces. The aim of this study was to evaluate the morphological changes produced by acid dissolution in Er:YAG laser irradiated dental enamel. Forty-eight enamel samples were divided into four groups (n = 12). GI (control); Groups II, III, and IV were irradiated with Er:YAG at 100 mJ (12.7 J/cm(2) ), 200 mJ (25.5 J/cm(2) ), and 300 mJ (38.2 J/cm(2) ), respectively, at 10 Hz without water irrigation. Enamel morphology was evaluated before-irradiation, after-irradiation, and after-acid dissolution, by scanning electron microscopy (SEM). Sample coating was avoided and SEM analysis was performed in a low-vacuum mode. To facilitate the location of the assessment area, a reference point was marked. Morphological changes produced by acid dissolution of irradiated enamel were observed, specifically on laser-induced undesired effects. These morphological changes were from mild to severe, depending on the presence of after-irradiation undesired effects.

  7. Oxidative stability of milk drinks containing structured lipids produced from sunflower oil and caprylic acid

    DEFF Research Database (Denmark)

    Timm Heinrich, Maike; Xu, Xuebing; Nielsen, Nina Skall;

    2003-01-01

    of adding potential antioxidants EDTA or gallic acid to the milk drink based on SL was investigated. The lipid type significantly affected the oxidative stability of the milk drinks: Milk drink based on SL oxidized faster than milk drink based on RL or SO. The reduced oxidative stability in the SL milk...... drink could not be ascribed was most likely influenced by the structure of the lipid and to a single factor, differences in the process applied to produce and purify the lipids. EDTA was a strong antioxidant, while gallic acid did not exert a distinct antioxidative effect in the milk drink based on SL....

  8. Methods of refining and producing dibasic esters and acids from natural oil feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Snead, Thomas E; Cohen, Steven A; Gildon, Demond L

    2015-04-07

    Methods are provided for refining natural oil feedstocks and producing dibasic esters and/or dibasic acids. The methods comprise reacting a terminal olefin with an internal olefin in the presence of a metathesis catalyst to form a dibasic ester and/or dibasic acid. In certain embodiments, the olefin esters are formed by reacting the feedstock in the presence of a metathesis catalyst under conditions sufficient to form a metathesized product comprising olefins and esters, separating the olefins from the esters in the metathesized product, and transesterifying the esters in the presence of an alcohol to form a transesterified product having olefin esters.

  9. Methods of refining and producing dibasic esters and acids from natural oil feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Snead, Thomas E.; Cohen, Steven A.; Gildon, Demond L.

    2016-03-15

    Methods are provided for refining natural oil feedstocks and producing dibasic esters and/or dibasic acids. The methods comprise reacting a terminal olefin with an internal olefin in the presence of a metathesis catalyst to form a dibasic ester and/or dibasic acid. In certain embodiments, the olefin esters are formed by reacting the feedstock in the presence of a metathesis catalyst under conditions sufficient to form a metathesized product comprising olefins and esters, separating the olefins from the esters in the metathesized product, and transesterifying the esters in the presence of an alcohol to form a transesterified product having olefin esters.

  10. Modular pathway rewiring of Saccharomyces cerevisiae enables high-level production of L-ornithine

    DEFF Research Database (Denmark)

    Qin, Jiufu; Zhou, Yongjin J.; Krivoruchko, Anastasia;

    2015-01-01

    Baker's yeast Saccharomyces cerevisiae is an attractive cell factory for production of chemicals and biofuels. Many different products have been produced in this cell factory by reconstruction of heterologous biosynthetic pathways; however, endogenous metabolism by itself involves many metabolite...... the potential to use yeast more extensively for low-cost production of many high-value amino-acid-derived chemicals.......Baker's yeast Saccharomyces cerevisiae is an attractive cell factory for production of chemicals and biofuels. Many different products have been produced in this cell factory by reconstruction of heterologous biosynthetic pathways; however, endogenous metabolism by itself involves many metabolites...... of industrial interest, and de-regulation of endogenous pathways to ensure efficient carbon channelling to such metabolites is therefore of high interest. Furthermore, many of these may serve as precursors for the biosynthesis of complex natural products, and hence strains overproducing certain pathway...

  11. Antimicrobial and immune modulatory effects of lactic acid and short chain fatty acids produced by vaginal microbiota associated with eubiosis and bacterial vaginosis

    OpenAIRE

    Muriel eAldunate; Daniela eSrbinovski; Anna C Hearps; Latham, Catherine F.; Paul A Ramsland; Raffi eGugasyan; Cone, Richard A.; Gilda eTachedjian

    2015-01-01

    Lactic acid and short chain fatty acids (SCFAs) produced by vaginal microbiota have reported antimicrobial and immune modulatory activities indicating their potential as biomarkers of disease and/or disease susceptibility. In asymptomatic women of reproductive-age the vaginal microbiota is comprised of lactic acid-producing bacteria that are primarily responsible for the production of lactic acid present at ~110 mM and acidifying the vaginal milieu to pH ~3.5. In contrast, bacterial vaginosis...

  12. 高产酿酒酵母SCY6生长与发酵条件的优化%Optimization of Growth and Fermentation Conditions for High Ethanol-Producing Saccharomyces cerevisiae Strain SCY6

    Institute of Scientific and Technical Information of China (English)

    顾华祥; 宋晨; 李迅

    2012-01-01

    采用高产酿酒酵母(Saccharomyces cerevisiae)SCY6发酵葡萄糖产乙醇,设计单因素试验考察该酵母菌株适宜的生长条件,采用正交试验优化酵母发酵产乙醇的条件.结果表明,该酵母菌株的最适生长温度和pH分别为28℃、5.0,培养基中葡萄糖质量分数为15%时其生长状态较好.正交试验结果表明,最适合该酿酒酵母发酵产乙醇的条件为玉米浆和(NH4)2SO4作为氮源,用量分别为20 g/L和2 g/L,接种量为4%,pH 5.0.在此条件下进行发酵,发酵液中乙醇体积分数可达7.77%,葡萄糖转化率达83.82%.%The high ethanol-producing Saccharomyces cerevisiae strain SCY6 was used to ferment glucose to ethanol. Single factor tests were conducted to optimize the cultivation conditions; while orthogonal design was adopted to optimize ethanol fermentation conditions. The results showed that the optimum temperature and pH for yeast growth was 28℃ and 5.0, respectively. The yeast grew well when mass ratio of glucose in YPD medium was 15%. The result of orthogonal test showed that the optimal ethanol fermentation conditions were, 2 g/L (NH4)2SO4 and 20g/L corn syrup as N source; inoculation dose, 4% volume fraction; and pH 5.0. The yield of ethanol reached 7.77%; and the conversion rate of glucose was 83.82% under these conditions.

  13. Metabolic engineering of microorganisms to produce omega-3 very long-chain polyunsaturated fatty acids.

    Science.gov (United States)

    Gong, Yangmin; Wan, Xia; Jiang, Mulan; Hu, Chuanjiong; Hu, Hanhua; Huang, Fenghong

    2014-10-01

    Omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs) have received growing attention due to their significant roles in human health. Currently the main source of these nutritionally and medically important fatty acids is marine fish, which has not met ever-increasing global demand. Microorganisms are an important alternative source also being explored. Although many microorganisms accumulate omega-3 LC-PUFAs naturally, metabolic engineering might still be necessary for significantly improving their yields. Here, we review recent research involving the engineering of microorganisms for production of omega-3 LC-PUFAs, including eicospentaenoic acid and docosohexaenoic acid. Both reconstitution of omega-3 LC-PUFA biosynthetic pathways and modification of existing pathways in microorganisms have demonstrated the potential to produce high levels of omega-3 LC-PUFAs. However, the yields of omega-3 LC-PUFAs in host systems have been substantially limited by potential metabolic bottlenecks, which might be caused partly by inefficient flux of fatty acid intermediates between the acyl-CoA and different lipid class pools. Although fatty acid flux in both native and heterologous microbial hosts might be controlled by several acyltransferases, evidence has suggested that genetic manipulation of one acyltransferase alone could significantly increase the accumulation of LC-PUFAs. The number of oleaginous microorganisms that can be genetically transformed is increasing, which will advance engineering efforts to maximize LC-PUFA yields in microbial strains.

  14. Electrochemical method for producing a biodiesel mixture comprising fatty acid alkyl esters and glycerol

    Science.gov (United States)

    Lin, YuPo J; St. Martin, Edward J

    2013-08-13

    The present invention relates to an integrated method and system for the simultaneous production of biodiesel from free fatty acids (via esterification) and from triglycerides (via transesterification) within the same reaction chamber. More specifically, one preferred embodiment of the invention relates to a method and system for the production of biodiesel using an electrodeionization stack, wherein an ion exchange resin matrix acts as a heterogeneous catalyst for simultaneous esterification and transesterification reactions between a feedstock and a lower alcohol to produce biodiesel, wherein the feedstock contains significant levels of free fatty acid. In addition, because of the use of a heterogeneous catalyst, the glycerol and biodiesel have much lower salt concentrations than raw biodiesel produced by conventional transesterification processes. The present invention makes it much easier to purify glycerol and biodiesel.

  15. Diverse Bacterial PKS Sequences Derived From Okadaic Acid-Producing Dinoflagellates

    Directory of Open Access Journals (Sweden)

    Kathleen S. Rein

    2008-05-01

    Full Text Available Okadaic acid (OA and the related dinophysistoxins are isolated from dinoflagellates of the genus Prorocentrum and Dinophysis. Bacteria of the Roseobacter group have been associated with okadaic acid producing dinoflagellates and have been previously implicated in OA production. Analysis of 16S rRNA libraries reveals that Roseobacter are the most abundant bacteria associated with OA producing dinoflagellates of the genus Prorocentrum and are not found in association with non-toxic dinoflagellates. While some polyketide synthase (PKS genes form a highly supported Prorocentrum clade, most appear to be bacterial, but unrelated to Roseobacter or Alpha-Proteobacterial PKSs or those derived from other Alveolates Karenia brevis or Crytosporidium parvum.

  16. NREL Creates New Pathways for Producing Biofuels and Acids from Cyanobacteria (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2012-10-01

    Cyanobacteria use photosynthesis to convert carbon dioxide into glycogen, a carbohydrate that is stored in the cells as an energy source. However, researchers at the National Renewable Energy Laboratory (NREL) have discovered that this photosynthesis can be redirected to produce lipids and valuable organic acids. The research could yield a new source of biofuels, because the lipids can potentially be extracted from the bacteria and converted into biodiesel.

  17. Physiological characterization of the high malic acid-producing Aspergillus oryzae strain 2103a-68

    DEFF Research Database (Denmark)

    Knuf, Christoph; Nookaew, Intawat; Remmers, Ilse

    2014-01-01

    13C flux analysis during exponential growth, supporting the success of the metabolic engineering strategy of increasing flux through the reductive cytosolic tricarboxylic acid (rTCA) branch. Additional cultivations using xylose and a glucose/xylose mixture demonstrated that A. oryzae is able...... of interest and corresponding enzyme activities were measured. On glucose as carbon source, 2103a-68 was able to secrete malic acid at a maximum specific production rate during stationary phase of 1.87 mmol (g dry weight (DW))−1 h−1 and with a yield of 1.49 mol mol−1. Intracellular fluxes were obtained using...... to efficiently metabolize pentoses and hexoses to produce malic acid at high titers, rates, and yields....

  18. Novel wine yeast with mutations in YAP1 that produce less acetic acid during fermentation.

    Science.gov (United States)

    Cordente, Antonio G; Cordero-Bueso, Gustavo; Pretorius, Isak S; Curtin, Christopher D

    2013-02-01

    Acetic acid, a byproduct formed during yeast alcoholic fermentation, is the main component of volatile acidity (VA). When present in high concentrations in wine, acetic acid imparts an undesirable 'vinegary' character that results in a significant reduction in quality and sales. Previously, it has been shown that saké yeast strains resistant to the antifungal cerulenin produce significantly lower levels of VA. In this study, we used a classical mutagenesis method to isolate a series of cerulenin-resistant strains, derived from a commercial diploid wine yeast. Four of the selected strains showed a consistent low-VA production phenotype after small-scale fermentation of different white and red grape musts. Specific mutations in YAP1, a gene encoding a transcription factor required for oxidative stress tolerance, were found in three of the four low-VA strains. When integrated into the genome of a haploid wine strain, the mutated YAP1 alleles partially reproduced the low-VA production phenotype of the diploid cerulenin-resistant strains, suggesting that YAP1 might play a role in (regulating) acetic acid production during fermentation. This study offers prospects for the development of low-VA wine yeast starter strains that could assist winemakers in their effort to consistently produce wine to definable quality specifications.

  19. Repeated Oral Administration of Oleanolic Acid Produces Cholestatic Liver Injury in Mice

    Directory of Open Access Journals (Sweden)

    Yasha Xu

    2013-03-01

    Full Text Available Oleanolic acid (OA is a triterpenoid and a fantastic molecule with many beneficial effects. However, high-doses and long-term use can produce adverse effects. This study aimed to characterize the hepatotoxic potential of OA. Mice were given OA at doses of 100–3,000 µmol/kg (45–1,350 mg/kg, po for 10 days, and the hepatotoxicity was determined by serum biochemistry, histopathology, and toxicity-related gene expression via real-time RT-PCR. Animal body weight loss was evident at OA doses of 1,000 µmol/kg and above. Serum alanine aminotransferase activities were increased in a dose-dependent manner, indicative of hepatotoxicity. Serum total bilirubin concentrations were increased, indicative of cholestasis. OA administration produced dose-dependent pathological lesions to the liver, including inflammation, hepatocellular apoptosis, necrosis, and feathery degeneration indicative of cholestasis. These lesions were evident at OA doses of 500 µmol/kg and above. Real-time RT-PCR revealed that OA produced dose-dependent increases in acute phase proteins (MT-1, Ho-1, Nrf2 and Nqo1, decreases in bile acid synthesis genes (Cyp7a1 and Cyp8b1, and decreases in liver bile acid transporters (Ntcp, Bsep, Oatp1a1, Oatp1b2, and Ostβ. Thus, the clinical use of OA and OA-type triterpenoids should balance the beneficial effects and toxicity potentials.

  20. Improved production, characterization and flocculation properties of poly (-glutamic acid produced from Bacillus Subtilis

    Directory of Open Access Journals (Sweden)

    Bhunia B

    2012-04-01

    Full Text Available Bacillus subtilis 2063 produced extracellular biopolymer whichshowed excellent flocculation activity. The biopolymer wasconfirmed as poly (γ-glutamic acid (PGA by using productcharacterization. HPLC profile showed that molecular weight ofPGA was found to be 5.8×106 Da. Improved production,Characterization and flocculation properties of PGA produced byBacillus species were studied. PGA produced by B. subtilis wasdevoid of any polysaccharides. The flocculating activity wasmarkedly stimulated by the addition of cations. The pH of reaction mixture also influenced the flocculating activity. Glycerol and ammonium chloride were found to be most useful carbon and nitrogen sources. An overall 4.24-fold increase in protease production was achieved in the design medium composed with Glycerol and ammonium chloride as a carbon and nitrogen sources as compared with basal media. PGA production increased significantly with optimized medium (21.42 gl-1 when compared with basal medium (5.06 gl-1.

  1. Structural and rheological characterisation of heteropolysaccharides produced by lactic acid bacteria in wheat and sorghum sourdough.

    Science.gov (United States)

    Galle, Sandra; Schwab, Clarissa; Arendt, Elke K; Gänzle, Michael G

    2011-05-01

    Hydrocolloids improve the volume, texture, and shelf life of bread. Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) during sourdough fermentation can replace hydrocolloids. It was the aim of this study to determine whether heteropolysaccharides (HePS) synthesized intracellularly from sugar nucleotides by glycosyltransferases are produced in wheat and gluten-free sorghum sourdough at effective levels. The HePS-producing strains Lactobacillus casei FUA3185, L. casei FUA3186, and Lactobacillus buchneri FUA3154 were used; Weissella cibaria 10M producing no EPS in the absence of sucrose served as control strain. Cell suspensions of L. buchneri in MRS showed the highest viscosity at low shear rate. Glycosyltransferase genes responsible of HePS formation in LAB were expressed in sorghum and wheat sourdough. However, only HePS produced by L. buchneri influenced the rheological properties of sorghum sourdoughs but not of wheat sourdoughs. Sorghum sourdough fermented with L. buchneri exhibited a low |G*| compared to the control, indicating a decrease in resistance to deformation. An increase in tan δ indicated decreased elasticity. The use of LAB producing HePS expands the diversity of EPS and increases the variety of cultures for use in baking.

  2. Incidence of Bacteriocins Produced by Food-Related Lactic Acid Bacteria Active towards Oral Pathogens

    Directory of Open Access Journals (Sweden)

    Konstantinos Papadimitriou

    2013-02-01

    Full Text Available In the present study we investigated the incidence of bacteriocins produced by 236 lactic acid bacteria (LAB food isolates against pathogenic or opportunistic pathogenic oral bacteria. This set of LAB contained several strains (≥17% producing bacteriocins active against food-related bacteria. Interestingly only Streptococcus macedonicus ACA-DC 198 was able to inhibit the growth of Streptococcus oralis, Streptococcus sanguinis and Streptococcus gordonii, while Lactobacillus fermentum ACA-DC 179 and Lactobacillus plantarun ACA-DC 269 produced bacteriocins solely against Streptococcus oralis. Thus, the percentage of strains that were found to produce bacteriocins against oral bacteria was ~1.3%. The rarity of bacteriocins active against oral LAB pathogens produced by food-related LAB was unexpected given their close phylogenetic relationship. Nevertheless, when tested in inhibition assays, the potency of the bacteriocin(s of S. macedonicus ACA-DC 198 against the three oral streptococci was high. Fourier-transform infrared spectroscopy combined with principal component analysis revealed that exposure of the target cells to the antimicrobial compounds caused major alterations of key cellular constituents. Our findings indicate that bacteriocins produced by food-related LAB against oral LAB may be rare, but deserve further investigation since, when discovered, they can be effective antimicrobials.

  3. The impact of zinc sulfate addition on the dynamic metabolic profiling of Saccharomyces cerevisiae subjected to long term acetic acid stress treatment and identification of key metabolites involved in the antioxidant effect of zinc.

    Science.gov (United States)

    Wan, Chun; Zhang, Mingming; Fang, Qing; Xiong, Liang; Zhao, Xinqing; Hasunuma, Tomohisa; Bai, Fengwu; Kondo, Akihiko

    2015-02-01

    The mechanisms of how zinc protects the cells against acetic acid toxicity and acts as an antioxidant are still not clear. Here we present results of the metabolic profiling of the eukaryotic model yeast species Saccharomyces cerevisiae subjected to long term high concentration acetic acid stress treatment in the presence and absence of zinc supplementation. Zinc addition decreased the release of reactive oxygen species (ROS) in the presence of chronic acetic acid stress. The dynamic changes in the accumulation of intermediates in central carbon metabolism were observed, and higher contents of intracellular alanine, valine and serine were observed by zinc supplementation. The most significant change was observed in alanine content, which is 3.51-fold of that of the control culture in cells in the stationary phase. Subsequently, it was found that 0.5 g L(-1) alanine addition resulted in faster glucose consumption in the presence of 5 g L(-1) acetic acid, and apparently decreased ROS accumulation in zinc-supplemented cells. This indicates that alanine exerted its antioxidant effect at least partially through the detoxification of acetic acid. In addition, intracellular glutathione (GSH) accumulation was enhanced by zinc addition, which is related to the protection of yeast cells from the oxidative injury caused by acetic acid. Our studies revealed for the first time that zinc modulates cellular amino acid metabolism and redox balance, especially biosynthesis of alanine and glutathione to exert its antioxidant effect.

  4. High Pdr12 levels in spoilage yeast (Saccharomyces cerevisiae) correlate directly with sorbic acid levels in the culture medium but are not sufficient to provide cells with acquired resistance to the food preservative.

    Science.gov (United States)

    Papadimitriou, Minas N B; Resende, Catarina; Kuchler, Karl; Brul, Stanley

    2007-01-25

    Sorbic acid is a commonly used food preservative against yeast and fungal food spoilage. Understanding its effect on the molecular physiology of yeast cells will allow the food industry to develop knowledge-based strategies to make more optimal use of its preservative action. Here we show that the yeast membrane protein Pdr12, previously shown to be prominently involved in sorbic acid resistance development in laboratory strains, was strongly induced by the presence of sorbic acid in the culture medium in Saccharomyces strains isolated from spoiled foods. Induction of Pdr12 expression was seen both under laboratory conditions and upon growth in a commercial soft drink. Induction was rapid and maintained for the duration of the stress. No Pdr12-like protein induction was seen in Zygosaccharomyces bailii or Zygosaccharomyces lentus, two well-known beverages spoilage organisms. Finally, unexpectedly, our studies showed for the first time that pre-inducing Pdr12p to maximal levels by subjecting cells to a mild sorbic acid stress did not lead to cells with an acquired resistance. Neither more rapid growth in the presence of the acid nor growth at higher sorbic acid concentrations at a given environmental pH was observed. Thus we have shown that while important in resistance development against sorbic acid, by itself induction of the pump is not sufficient to acquire resistance to the preservative.

  5. 21 CFR 172.225 - Methyl and ethyl esters of fatty acids produced from edible fats and oils.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methyl and ethyl esters of fatty acids produced... Methyl and ethyl esters of fatty acids produced from edible fats and oils. Methyl esters and ethyl esters... following prescribed conditions: (a) The additive consists of a mixture of either methyl or ethyl esters...

  6. Determination of boron in produced water using the carminic acid assay.

    Science.gov (United States)

    Floquet, Cedric F A; Sieben, Vincent J; MacKay, Bruce A; Mostowfi, Farshid

    2016-04-01

    Using the carminic acid assay, we determined the concentration of boron in oilfield waters. We investigated the effect of high concentrations of salts and dissolved metals on the assay performance. The influence of temperature, development time, reagent concentration, and water volume was studied. Ten produced and flowback water samples of different origins were measured, and the method was successfully validated against ICP-MS measurements. In water-stressed regions, produced water is a potential source of fresh water for irrigation, industrial applications, or consumption. Therefore, boron concentration must be determined and controlled to match the envisaged waste water reuse. Fast, precise, and onsite measurements are needed to minimize errors introduced by sample transportation to laboratories. We found that the optimum conditions for our application were a 5:1 mixing volume ratio (reagent to sample), a 1 g L(-1) carminic acid concentration in 99.99% sulfuric acid, and a 30 min reaction time at ambient temperature (20 °C to 23 °C). Absorption values were best measured at 610 nm and 630 nm and baseline corrected at 865 nm. Under these conditions, the sensitivity of the assay to boron was maximized while its cross-sensitivity to dissolved titanium, iron, barium and zirconium was minimized, alleviating the need for masking agents and extraction methods.

  7. Tandem mass spectrometry of poly(methacrylic Acid) oligomers produced by negative mode electrospray ionization.

    Science.gov (United States)

    Giordanengo, Rémi; Viel, Stéphane; Allard-Breton, Béatrice; Thévand, André; Charles, Laurence

    2009-01-01

    Dissociation of small poly(methyl acrylic acid) (PMAA) anions produced by electrospray was characterized by tandem mass spectrometry. Upon collisional activation, singly, and doubly deprotonated PMAA oligomers were shown to fragment via two major reactions, dehydration and decarboxylation. The elimination of a water molecule would occur between two consecutive acid groups in a charged-remote mechanism, giving rise to cyclic anhydrides, and was shown to proceed as many times as pairs of neutral pendant groups were available. As a result, the number of dehydration steps, together with the abundance of the fragment ions produced after the release of all water molecules, revealed the polymerization degree of the molecule in the particular case of doubly charged oligomers. For singly deprotonated molecules, the exact number of MAA units could be reached from the number of carbon dioxide molecules successively eliminated from the fully dehydrated precursor ions. In contrast to dehydration, decarboxylation reactions would proceed via a charge-induced mechanism. The proposed dissociation mechanisms are consistent with results commonly reported in thermal degradation studies of poly(acrylic acid) resins and were supported by accurate mass measurements. These fragmentation rules were successfully applied to characterize a polymeric impurity detected in the tested PMAA sample.

  8. Characterization of five fungal endophytes producing Cajaninstilbene acid isolated from pigeon pea [Cajanus cajan (L.) Millsp].

    Science.gov (United States)

    Gao, Yuan; Zhao, Jin Tong; Zu, Yuan Gang; Fu, Yu Jie; Wang, Wei; Luo, Meng; Efferth, Thomas

    2011-01-01

    Five fungal endophytes (K4, K5, K6, K9, K14) producing Cajaninstilbene acid (CSA, 3-hydroxy-4-prenyl-5-methoxystilbene-2-carboxylic acid) were isolated from the roots of pigeon pea [Cajanus cajan (L.) Millsp.]. CSA is responsible for the prominent pharmacological activities in pigeon pea. The amount of CSA in culture solution varied among the five fungal endophytes. K4 produced the highest levels of CSA (1037.13 µg/L) among the endophytes tested after incubation for five days. Both morphological characteristics and molecular methods were used for species identification of fungal endophytes. The five endophytic isolates were characterized by analyzing the internal transcribed spacer (ITS) rRNA and β-tubulin genes. The K4, K5, K9 and K14 strains isolated from pigeon pea roots were found to be closely related to the species Fusarium oxysporum. K6 was identified as Neonectria macrodidym. The present study is the first report on the isolation and identification of fungal endophytes producing CSA in pigeon pea. The study also provides a scientific base for large scale production of CSA.

  9. Characterization of five fungal endophytes producing Cajaninstilbene acid isolated from pigeon pea [Cajanus cajan (L. Millsp].

    Directory of Open Access Journals (Sweden)

    Yuan Gao

    Full Text Available Five fungal endophytes (K4, K5, K6, K9, K14 producing Cajaninstilbene acid (CSA, 3-hydroxy-4-prenyl-5-methoxystilbene-2-carboxylic acid were isolated from the roots of pigeon pea [Cajanus cajan (L. Millsp.]. CSA is responsible for the prominent pharmacological activities in pigeon pea. The amount of CSA in culture solution varied among the five fungal endophytes. K4 produced the highest levels of CSA (1037.13 µg/L among the endophytes tested after incubation for five days. Both morphological characteristics and molecular methods were used for species identification of fungal endophytes. The five endophytic isolates were characterized by analyzing the internal transcribed spacer (ITS rRNA and β-tubulin genes. The K4, K5, K9 and K14 strains isolated from pigeon pea roots were found to be closely related to the species Fusarium oxysporum. K6 was identified as Neonectria macrodidym. The present study is the first report on the isolation and identification of fungal endophytes producing CSA in pigeon pea. The study also provides a scientific base for large scale production of CSA.

  10. Lipid characterization of an arachidonic acid-rich oil producing fungus Mortierella alpina

    Institute of Scientific and Technical Information of China (English)

    Wenjia Wu; Jiacheng Yan; Xiaojun Ji; Xin Zhang; Jingsheng Shang; Lina Sun; Lujing Ren; He Huang

    2015-01-01

    Mortierel a alpina has been considered as the most effective producer of arachidonic acid (ARA)-rich oil. It was found that several methods could improve the percentage of ARA in total lipids successful y, as they activated the desaturation system on the endoplasmic reticulum. Additionally, in M. alpina the ARA exists in several forms, such as triacylglycerol (TAG), and diacylglycerol (DAG). These forms are caused by different acyltransferases and they determine the nutrient value of the microbial oil. However, few works revealed de-tailed fatty acid distribution among lipid classes, which to some extent impeded the accurate regulation in ARA accumulation. Herein, this paper gives information on the accumulation process of main lipid classes and the changes of fatty acid composition in these lipids during ARA accumulation period in M. alpina. The result dem-onstrates that TAG was the dominant component of the total lipids, and it is the main form for ARA storage. The ARA enrichment stage occurred during 168–192 h when the amount of total lipids maintained steady. Further analysis indicated that the newly formed ARA-TAG might come from the incorporation and modification of sat-urated and monounsaturated fatty acids in other lipid classes. This work could be helpful for further optimization of ARA-rich TAG production.

  11. ISOLATION AND IDENTIFICATION OF LACTIC ACID PRODUCING BACTERIA FROM CAMEL MILK

    Directory of Open Access Journals (Sweden)

    Toqeer Ahmad, Rashida Kanwal, Izhar Hussain Athar1, Najam Ayub

    2002-03-01

    Full Text Available Lactic acid bacteria (LAB were isolated from camel milk by culturing the camel milk on specific media and pure culture was obtained by sub culturing. Purification of culture was confirmed by Gram's staining and identified by different bio-chemical tests. Camel milk contains lactic acid producing bacteria including Strpptococci such as S. cremoris and S. lactis and Lactobacilli such as L. acidophilus L. acidophilus grows more rapidly in camel milk than others as its growth is supported by camel milk. A variety of food can be preserved by lactic acid fermentation, so starter culture was prepared from strains which were isolated from camel milk. Camel and buffalo's milk cheese was prepared by using starter culture. The strains isolated from camel milk were best for acid production and can coagulate the milk in less lime. Camel milk cheese was prepared and compared with buffalo's milk cheese. It is concluded that cheese can be prepared successfully from camel milk and better results can be obtained by coagulating milk with starter culture.

  12. Cell recycled culture of succinic acid-producing Anaerobiospirillum succiniciproducens using an internal membrane filtration system.

    Science.gov (United States)

    Lee, Pyung-Cheon; Lee, Sang-Yup; Chang, Ho-Nam

    2008-07-01

    Cell recycled culture of succinic acid-producing Anaerobiospirillum succiniciproducens was anaerobically carried out using an internal membrane filter module in order to examine the physiological response of A. succiniciproducens to a high-cell-density environment. The optimal growth of A. succiniciproducens and its enhanced succinic acid productivity were observed under CO2-rich conditions, established by adding NaHCO3 and Na2CO3, in the cell recycled system. A. succiniciproducens grew up to 6.50 g-DCW/l, the highest cell concentration obtained so far, in cell recycled cultures. The cells did not change their morphology, which is known to be easily changed in unfavorable or stress environments. The maximum productivity of succinic acid was about 3.3 g/l/h, which is 3.3 times higher than those obtained in batch cultures. These results can serve as a guide for designing highly efficient cell recycled systems for succinic acid at a commercial level.

  13. 酿酒酵母对弱有机酸胁迫的应激机制研究进展%Research progress on weak organic acid stress mechanism of Saccharomyces cerevisiae

    Institute of Scientific and Technical Information of China (English)

    刘兴艳; 贾博; 赵芳; 王成; 李静援; 战吉宬; 黄卫东

    2013-01-01

    Yeast Saccharomyces cerevisiae is the main microorganism in the production of liquor,but fermentation environment is always disadvantageous to its growth.It is always exposed to several stress conditions including low pH stress resulting from weak organic acid.Yeast cells have developed a common response to environmental adverse conditions,but there are some differences among different stress.Researches on weak organic acid stress mechanism of Saccharomyces cerevisiae in recent years are reviewed in this paper,including gene expression,transcript expression and protein expression.ATP binding cassette transporter Pdrl2 and its transcription factor Warlp,HOG-MAPK pathway,FPS1 aquaglyceroporin,plasma membrane H+-ATPase,superoxide dismutase (SOD),catalase(CAT) and interaction of weak acid stress with other stress are all discussed.We hope it could provide certain reference for better research on weak acid stress mechanism of Saccharomyces cerevisiae.%酿酒酵母是生产酒类产品的主要微生物,而生产中的发酵环境对酿酒酵母来说是一种不利的生长代谢环境,存在多种胁迫因素,其中就包括弱有机酸引起的低pH胁迫.酿酒酵母应对胁迫环境,有自身一套完备的适应机制,不同胁迫应对机制既有相同之处亦有不同之处.本文概括了近年来酿酒酵母对弱有机酸应激机制的研究热点,主要从弱有机酸胁迫的基因表达、转录表达以及蛋白质表达3个水平进行阐述,涉及ATP结合区转运子Pdrl2及其转录因子Warlp,HOG-MAPK途径,水通道蛋白Fpslp,质膜H+-ATP酶,SOD,CAT,以及弱有机酸与其他胁迫的交互作用,旨在为更好地研究酿酒酵母的弱有机酸应激机制提供一定的参考.

  14. Screening of phenylpyruvic acid producers and optimization of culture conditions in bench scale bioreactors.

    Science.gov (United States)

    Coban, Hasan B; Demirci, Ali; Patterson, Paul H; Elias, Ryan J

    2014-11-01

    Alpha keto acids are deaminated forms of amino acids that have received significant attention as feed and food additives in the agriculture and medical industries. To date, their production has been commonly performed at shake-flask scale with low product concentrations. In this study, production of phenylpyruvic acid (PPA), which is the alpha keto acid of phenylalanine was investigated. First, various microorganisms were screened to select the most efficient producer. Thereafter, growth parameters (temperature, pH, and aeration) were optimized in bench scale bioreactors to maximize both PPA and biomass concentration in bench scale bioreactors, using response surface methodology. Among the four different microorganisms evaluated, Proteus vulgaris was the most productive strain for PPA production. Optimum temperature, pH, and aeration conditions were determined as 34.5 °C, 5.12, and 0.5 vvm for PPA production, whereas 36.9 °C, pH 6.87, and 0.96 vvm for the biomass production. Under these optimum conditions, PPA concentration was enhanced to 1,054 mg/L, which was almost three times higher than shake-flask fermentation concentrations. Moreover, P. vulgaris biomass was produced at 3.25 g/L under optimum conditions. Overall, this study demonstrated that optimization of growth parameters improved PPA production in 1-L working volume bench-scale bioreactors compared to previous studies in the literature and was a first step to scale up the production to industrial production.

  15. Structural characterization of an acidic exoheteropolysaccharide produced by the nitrogen-fixing bacterium Burkholderia tropica.

    Science.gov (United States)

    Serrato, Rodrigo V; Sassaki, Guilherme L; Gorin, Philip A J; Cruz, Leonardo M; Pedrosa, Fábio O; Choudhury, Biswa; Carlson, Russell W; Iacomini, Marcello

    2008-09-05

    An acidic exopolysaccharide (EPS) produced by the diazotrophic bacterium Burkholderia tropica, strain Ppe8, was isolated from the culture supernatant of bacteria grown in a synthetic liquid medium containing mannitol and glutamate. Monosaccharide composition showed Rha, Glc and GlcA in a 2.0:2.0:1.0 molar ratio, respectively. Further structural characterization was performed by a combination of NMR, mass spectrometry and chemical methods. Partial acid hydrolysis of EPS provided a mixture of acidic oligosaccharides that were characterized by ESI-MS, giving rise to ions with m/z 193 (GlcA-H)(-), 339 (GlcA,Rha-H)(-), 501 (GlcA,Rha,Glc-H)(-), 647 (GlcA,Rha2,Glc,-H)(-), 809 (GlcA,Rha2,Glc2,-H)(-) and 851 (GlcA,Rha2,Glc2,OAc-H)(-). Carboxyreduced EPS (EPS-CR) had Glc and Rha in a 3:2 ratio, present as d- and l-enantiomers, respectively. Methylation and NMR analysis of EPS and EPS-CR showed a main chain containing 2,4-di-O-Rhap, 3-O-Rhap and 4-O-Glcp. A GlcA side chain unit was found in the acidic EPS, substituting O-4 of α-l-Rhap units. This was observed as a non-reducing end unit of glucopyranose in the EPS-CR. Acetyl esters occured at O-2 of β-l-Rhap units. From the combined results herein, we determined the structure of the exocellular polysaccharide produced by B. tropica, Ppe8, as being a pentasaccharide repeating unit as shown.

  16. Neonatal striatal grafts prevent lethal syndrome produced by bilateral intrastriatal injection of kainic acid.

    Science.gov (United States)

    Tulipan, N; Huang, S; Whetsell, W O; Allen, G S

    1986-07-02

    It is reported that unilateral grafts of neonatal striatal tissue protect the recipient from the lethal aphagia and adipsia produced by bilateral intrastriatal injection of 10 nmol of kainic acid in rats. It is shown that neither adult striatum nor neonatal tissue from other sites have the same lifesaving effect and that the salutary effect of the graft is dependent upon graft survival. Grafts from a histoincompatible donor are apparently rejected, leading to the death of the recipient. Cyclosporine inhibits rejection thereby enabling recipient survival. It is postulated that the graft exerts a neurohumoral influence that protects the striatum from the toxic effect of kainate.

  17. Comparative amino acid sequence analysis of hemolysins produced by Vibrio hollisae and Vibrio parahaemolyticus.

    OpenAIRE

    Yoh, M; Honda, T.; Miwatani, T; Tsunasawa, S; Sakiyama, F

    1989-01-01

    Vibrio hollisae produces a hemolysin (Vh-rTDH) that is related to the thermostable direct hemolysin of Vibrio parahaemolyticus (Vp-TDH). Although both hemolysins are essentially similar biologically and immunologically, they differ markedly in heat stability; Vp-TDH is heat stable, whereas Vh-rTDH is heat labile. To elucidate the relationships between their characteristics and molecular structures, we analyzed the amino acid sequence of Vh-rTDH and compared it with that of Vp-TDH. Vh-rTDH con...

  18. Gluconacetobacter medellinensis sp. nov., cellulose- and non-cellulose-producing acetic acid bacteria isolated from vinegar.

    Science.gov (United States)

    Castro, Cristina; Cleenwerck, Ilse; Trcek, Janja; Zuluaga, Robin; De Vos, Paul; Caro, Gloria; Aguirre, Ricardo; Putaux, Jean-Luc; Gañán, Piedad

    2013-03-01

    The phylogenetic position of a cellulose-producing acetic acid bacterium, strain ID13488, isolated from commercially available Colombian homemade fruit vinegar, was investigated. Analyses using nearly complete 16S rRNA gene sequences, nearly complete 16S-23S rRNA gene internal transcribed spacer (ITS) sequences, as well as concatenated partial sequences of the housekeeping genes dnaK, groEL and rpoB, allocated the micro-organism to the genus Gluconacetobacter, and more precisely to the Gluconacetobacter xylinus group. Moreover, the data suggested that the micro-organism belongs to a novel species in this genus, together with LMG 1693(T), a non-cellulose-producing strain isolated from vinegar by Kondo and previously classified as a strain of Gluconacetobacter xylinus. DNA-DNA hybridizations confirmed this finding, revealing a DNA-DNA relatedness value of 81 % between strains ID13488 and LMG 1693(T), and values <70 % between strain LMG 1693(T) and the type strains of the closest phylogenetic neighbours. Additionally, the classification of strains ID13488 and LMG 1693(T) into a single novel species was supported by amplified fragment length polymorphism (AFLP) and (GTG)5-PCR DNA fingerprinting data, as well as by phenotypic data. Strains ID13488 and LMG 1693(T) could be differentiated from closely related species of the genus Gluconacetobacter by their ability to produce 2- and 5-keto-d-gluconic acid from d-glucose, their ability to produce acid from sucrose, but not from 1-propanol, and their ability to grow on 3 % ethanol in the absence of acetic acid and on ethanol, d-ribose, d-xylose, sucrose, sorbitol, d-mannitol and d-gluconate as carbon sources. The DNA G+C content of strains ID13488 and LMG 1693(T) was 58.0 and 60.7 mol%, respectively. The major ubiquinone of LMG 1693(T) was Q-10. Taken together these data indicate that strains ID13488 and LMG 1693(T) represent a novel species of the genus Gluconacetobacter for which the name Gluconacetobacter

  19. Production of volatile and sulfur compounds by ten Saccharomyces cerevisiae strains inoculated in Trebbiano must

    Directory of Open Access Journals (Sweden)

    Francesca ePatrignani

    2016-03-01

    Full Text Available In wines, the presence of sulphur compounds is the resulting of several contributions among which yeast metabolism. The characterization of the starter Saccharomyces cerevisiae needs to be performed also taking into account this ability even if evaluated together with the overall metabolic profile. In this perspective, principal aim of this experimental research was the evaluation of the volatile profiles, throughout GC/MS technique coupled with solid phase micro extraction, of wines obtained throughout the fermentation of 10 strains of Saccharomyces cerevisiae. In addition, the production of sulphur compounds was further evaluated by using a gas-chromatograph coupled with a Flame Photometric Detector. Specifically, the ten strains were inoculated in Trebbiano musts and the fermentations were monitored for 19 days. In the produced wines, volatile and sulphur compounds as well as amino acid concentrations were investigated. Also the physico-chemical characteristics of the wines and their electronic nose profiles were evaluated.

  20. Novel extremely acidic lipases produced from Bacillus species using oil substrates.

    Science.gov (United States)

    Saranya, P; Kumari, H Sukanya; Jothieswari, M; Rao, B Prasad; Sekaran, G

    2014-01-01

    The extremely acidophilic microorganisms Bacillus pumilus and Bacillus subtilis were isolated from soil collected from the commercial edible oil and fish oil extraction industry. Optimization of conditions for acidic lipase production from B. pumilus and B. subtilis using palm oil and fish oil, respectively, was carried out using response surface methodology. The extremely acidic lipases, thermo-tolerant acidic lipase (TAL) and acidic lipase (AL), were produced by B. pumilus and B. subtilis, respectively. The optimum conditions for B. pumilus obtaining the maximum activity (1,100 U/mL) of TAL were fermentation time, 96 h; pH, 1; temperature, 50 °C; concentration of palm oil, 50 g/L. After purification, a 7.1-fold purity of lipase with specific activity of 5,173 U/mg protein was obtained. The molecular weight of the TAL was 55 kDa. The AL from B. subtilis activity was 214 U/mL at a fermentation time of 72 h; pH, 1; temperature, 35 °C; concentration of fish oil, 30 g/L; maltose concentration, 10 g/L. After purification, an 11.4-fold purity of lipase with specific activity of 2,189 U/mg protein was obtained. The molecular weight of the extremely acidic lipase was 22 kDa. The functional groups of lipases were determined by Fourier transform-infrared (FT-IR) spectroscopy.

  1. Identification and quantification of antifungal compounds produced by lactic acid bacteria and propionibacteria.

    Science.gov (United States)

    Le Lay, Céline; Coton, Emmanuel; Le Blay, Gwenaëlle; Chobert, Jean-Marc; Haertlé, Thomas; Choiset, Yvan; Van Long, Nicolas Nguyen; Meslet-Cladière, Laurence; Mounier, Jérôme

    2016-12-19

    Fungal growth in bakery products represents the most frequent cause of spoilage and leads to economic losses for industrials and consumers. Bacteria, such as lactic acid bacteria and propionibacteria, are commonly known to play an active role in preservation of fermented food, producing a large range of antifungal metabolites. In a previous study (Le Lay et al., 2016), an extensive screening performed both in vitro and in situ allowed for the selection of bacteria exhibiting an antifungal activity. In the present study, active supernatants against Penicillium corylophilum and Aspergillus niger were analyzed to identify and quantify the antifungal compounds associated with the observed activity. Supernatant treatments (pH neutralization, heating and addition of proteinase K) suggested that organic acids played the most important role in the antifungal activity of each tested supernatant. Different methods (HPLC, mass spectrometry, colorimetric and enzymatic assays) were then applied to analyze the supernatants and it was shown that the main antifungal compounds corresponded to lactic, acetic and propionic acids, ethanol and hydrogen peroxide, as well as other compounds present at low levels such as phenyllactic, hydroxyphenyllactic, azelaic and caproic acids. Based on these results, various combinations of the identified compounds were used to evaluate their effect on conidial germination and fungal growth of P. corylophilum and Eurotium repens. Some combinations presented the same activity than the bacterial culture supernatant thus confirming the involvement of the identified molecules in the antifungal activity. The obtained results suggested that acetic acid was mainly responsible for the antifungal activity against P. corylophilum and played an important role in E. repens inhibition.

  2. Implications for global climate change from microbially-produced acid mine drainage

    Science.gov (United States)

    Norlund, K. L.; Hitchcock, A. P.; Warren, L. A.

    2009-05-01

    Microbial catalysis of sulphur cycling in acid mine drainage (AMD) environments is well known but the reaction pathways are poorly characterised. These reaction pathways involve both acid-consuming and acid- generating steps, with important consequences for overall AMD production as well as sulphur and carbon global biogeochemical cycles. Mining-associated sulphuric acid has been implicated in climate change through the weathering of carbonate minerals resulting in the release of 29 Tg C/year as carbon dioxide. Understanding of microbial AMD generation is based predominantly on studies of Acidithiobacillus ferrooxidans despite the knowledge that other environmentally common strains of bacteria are also active sulphur oxidizers and that microbial consortia are likely very important in environmental processes. Using an integrated experimental approach including geochemical experimentation, scanning transmission X-ray microscopy (STXM) and fluorescent in situ hybridization (FISH), we document a novel syntrophic sulphur metabolism involving two common mine bacteria: autotrophic sulphur oxidizing Acidithiobacillus ferrooxidans and heterotrophic Acidiphilium spp. The proposed sulphur geochemistry associated with this bacterial consortium produces 40-90% less acid than expected based on abiotic AMD models, with significant implications for both AMD mitigation and AMD carbon flux modelling. The two bacterial strains are specifically spatially segregated within a macrostructure of extracellular polymeric substance (EPS) that provides the necessary microgeochemical conditions for coupled sulphur oxidation and reduction reactions. STXM results identify multiple sulphur oxidation states associated with the pods, indicating that they are the sites of active sulphur disproportionation and recycling. Recent laboratory experimentation using type culture strains of the bacteria involved in pod-formation suggesting that this phenomenon is likely to be widespread in environments

  3. Current state of purification, isolation and analysis of bacteriocins produced by lactic acid bacteria.

    Science.gov (United States)

    Kaškonienė, Vilma; Stankevičius, Mantas; Bimbiraitė-Survilienė, Kristina; Naujokaitytė, Gintarė; Šernienė, Loreta; Mulkytė, Kristina; Malakauskas, Mindaugas; Maruška, Audrius

    2017-02-01

    The scientific interest for the search of natural means of microbial inhibitors has not faded for several years. A search of natural antibiotics, so-called bacteriocins which are produced by lactic acid bacteria (LAB), gains a huge attention of the scientists in the last century, in order to reduce the usage of synthetic food additives. Pure bacteriocins with wide spectra of antibacterial activity are promising among the natural biopreservatives. The usage of bacteriocin(s) producing LAB as starter culture for the fermentation of some food products, in order to increase their shelf-life, when synthetic preservatives are not allowable, is also possible. There are a lot of studies focusing on the isolation of new bacteriocins from traditional fermented food, dairy products and other foods or sometimes even from unusual non-food matrices. Bacteriocins producing bacteria have been isolated from different sources with the different antibacterial activity against food-borne microorganisms. This review covers the classification of bacteriocins, diversity of sources of bacteriocin(s) producing LAB, antibacterial spectra of isolated bacteriocins and analytical methods for the bacteriocin purification and analysis within the last 15 years.

  4. Exopolysaccharides produced by lactic acid bacteria: from health-promoting benefits to stress tolerance mechanisms.

    Science.gov (United States)

    Caggianiello, Graziano; Kleerebezem, Michiel; Spano, Giuseppe

    2016-05-01

    A wide range of lactic acid bacteria (LAB) is able to produce capsular or extracellular polysaccharides, with various chemical compositions and properties. Polysaccharides produced by LAB alter the rheological properties of the matrix in which they are dispersed, leading to typically viscous and "ropy" products. Polysaccharides are involved in several mechanisms such as prebiosis and probiosis, tolerance to stress associated to food process, and technological properties of food. In this paper, we summarize the beneficial properties of exopolysaccharides (EPS) produced by LAB with particular attention to prebiotic properties and to the effect of exopolysaccharides on the LAB-host interaction mechanisms, such as bacterial tolerance to gastrointestinal tract conditions, ability of ESP-producing probiotics to adhere to intestinal epithelium, their immune-modulatory activity, and their role in biofilm formation. The pro-technological aspect of exopolysaccharides is discussed, focusing on advantageous applications of EPS in the food industry, i.e., yogurt and gluten-free bakery products, since it was found that these microbial biopolymers positively affect the texture of foods. Finally, the involvement of EPS in tolerance to stress conditions that are commonly encountered in fermented beverages such as wine is discussed.

  5. Methane reacts with heteropolyacids chemisorbed on silica to produce acetic acid under soft conditions

    KAUST Repository

    Sun, Miao

    2013-01-16

    Selective functionalization of methane at moderate temperature is of crucial economic, environmental, and scientific importance. Here, we report that methane reacts with heteropolyacids (HPAs) chemisorbed on silica to produce acetic acid under soft conditions. Specially, when chemisorbed on silica, H 4SiW12O40, H3PW12O 40, H4SiMo12O40, and H 3PMo12O40 activate the primary C-H bond of methane at room temperature and atmospheric pressure. With these systems, acetic acid is produced directly from methane, in a single step, in the absence of Pd and without adding CO. Extensive surface characterization by solid-state NMR spectroscopy, IR spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy suggests that C-H activation of methane is triggered by the protons in the HPA-silica interface with concerted reduction of the Keggin cage, leading to water formation and hydration of the interface. This is the simplest and mildest way reported to date to functionalize methane. © 2012 American Chemical Society.

  6. Visualization of sialic acid produced on bacterial cell surfaces by lectin staining.

    Science.gov (United States)

    Kajiwara, Hitomi; Toda, Munetoyo; Mine, Toshiki; Nakada, Hiroshi; Wariishi, Hiroyuki; Yamamoto, Takeshi

    2010-01-01

    Oligosaccharides containing N-acetylneuraminic acid on the cell surface of some pathogenic bacteria are important for host-microbe interactions. N-acetylneuraminic acid (Neu5Ac) plays a major role in the pathogenicity of bacterial pathogens. For example, cell surface sialyloligosaccharide moieties of the human pathogen Haemophilus influenzae are involved in virulence and adhesion to host cells. In this study, we have established a method of visualizing Neu5Ac linked to a glycoconjugate on the bacterial cell surface based on lectin staining. Photobacterium damselae strain JT0160, known to produce a-2,6-sialyltransferase, was revealed to possess Neu5Ac by HPLC. Using the strain, a strong Sambucus sieboldiana lectin-binding signal was detected. The bacteria producing α-2,6-sialyltransferases could be divided into two groups: those with a lot of α-2,6-linked Neu5Ac on the cell surface and those with a little. In the present study, we developed a useful method for evaluating the relationship between Neu5Ac expression on the cell surface and the degree of virulence of marine bacteria.

  7. Lactic acid bacteria producing B-group vitamins: a great potential for functional cereals products.

    Science.gov (United States)

    Capozzi, Vittorio; Russo, Pasquale; Dueñas, María Teresa; López, Paloma; Spano, Giuseppe

    2012-12-01

    Wheat contains various essential nutrients including the B group of vitamins. However, B group vitamins, normally present in cereals-derived products, are easily removed or destroyed during milling, food processing or cooking. Lactic acid bacteria (LAB) are widely used as starter cultures for the fermentation of a large variety of foods and can improve the safety, shelf life, nutritional value, flavor and overall quality of the fermented products. In this regard, the identification and application of strains delivering health-promoting compounds is a fascinating field. Besides their key role in food fermentations, several LAB found in the gastrointestinal tract of humans and animals are commercially used as probiotics and possess generally recognized as safe status. LAB are usually auxotrophic for several vitamins although certain strains of LAB have the capability to synthesize water-soluble vitamins such as those included in the B group. In recent years, a number of biotechnological processes have been explored to perform a more economical and sustainable vitamin production than that obtained via chemical synthesis. This review article will briefly report the current knowledge on lactic acid bacteria synthesis of vitamins B2, B11 and B12 and the potential strategies to increase B-group vitamin content in cereals-based products, where vitamins-producing LAB have been leading to the elaboration of novel fermented functional foods. In addition, the use of genetic strategies to increase vitamin production or to create novel vitamin-producing strains will be also discussed.

  8. Improving phosphorus availability in an acid soil using organic amendments produced from agroindustrial wastes.

    Science.gov (United States)

    Ch'ng, Huck Ywih; Ahmed, Osumanu Haruna; Majid, Nik Muhamad Ab

    2014-01-01

    In acid soils, soluble inorganic phosphorus is fixed by aluminium and iron. To overcome this problem, acid soils are limed to fix aluminium and iron but this practice is not economical. The practice is also not environmentally friendly. This study was conducted to improve phosphorus availability using organic amendments (biochar and compost produced from chicken litter and pineapple leaves, resp.) to fix aluminium and iron instead of phosphorus. Amending soil with biochar or compost or a mixture of biochar and compost increased total phosphorus, available phosphorus, inorganic phosphorus fractions (soluble inorganic phosphorus, aluminium bound inorganic phosphorus, iron bound inorganic phosphorus, redundant soluble inorganic phosphorus, and calcium bound phosphorus), and organic phosphorus. This was possible because the organic amendments increased soil pH and reduced exchangeable acidity, exchangeable aluminium, and exchangeable iron. The findings suggest that the organic amendments altered soil chemical properties in a way that enhanced the availability of phosphorus in this study. The amendments effectively fixed aluminium and iron instead of phosphorus, thus rendering phosphorus available by keeping the inorganic phosphorus in a bioavailable labile phosphorus pool for a longer period compared with application of Triple Superphosphate without organic amendments.

  9. Improving Phosphorus Availability in an Acid Soil Using Organic Amendments Produced from Agroindustrial Wastes

    Directory of Open Access Journals (Sweden)

    Huck Ywih Ch’ng

    2014-01-01

    Full Text Available In acid soils, soluble inorganic phosphorus is fixed by aluminium and iron. To overcome this problem, acid soils are limed to fix aluminium and iron but this practice is not economical. The practice is also not environmentally friendly. This study was conducted to improve phosphorus availability using organic amendments (biochar and compost produced from chicken litter and pineapple leaves, resp. to fix aluminium and iron instead of phosphorus. Amending soil with biochar or compost or a mixture of biochar and compost increased total phosphorus, available phosphorus, inorganic phosphorus fractions (soluble inorganic phosphorus, aluminium bound inorganic phosphorus, iron bound inorganic phosphorus, redundant soluble inorganic phosphorus, and calcium bound phosphorus, and organic phosphorus. This was possible because the organic amendments increased soil pH and reduced exchangeable acidity, exchangeable aluminium, and exchangeable iron. The findings suggest that the organic amendments altered soil chemical properties in a way that enhanced the availability of phosphorus in this study. The amendments effectively fixed aluminium and iron instead of phosphorus, thus rendering phosphorus available by keeping the inorganic phosphorus in a bioavailable labile phosphorus pool for a longer period compared with application of Triple Superphosphate without organic amendments.

  10. Isolation and characterization of lactic acid bacteria strains with ornithine producing capacity from natural sea salt.

    Science.gov (United States)

    Yu, Jin-Ju; Oh, Suk-Heung

    2010-08-01

    Two lactic acid bacteria (LAB) having ornithine-producing capacity were isolated from Korean natural sea salt. They were Gram-positive, short rod-type bacteria, and able to grow anaerobically with CO(2) production. The isolates grew well on MRS broth at 30-37 degrees C and a pH of 6.5-8.0. The optimum temperature and pH for growth are 37 degrees C and pH 7.0. The isolates fermented D-ribose, D-galactose, D-lactose, D-maltose, Dcellobiose, D-tagatose, D-trehalose, sucrose, D-melezitose, gentiobiose, D-glucose but not D-melibiose, inositol, and L-sorbose. The 16S rDNA sequences of the two isolates showed 99.5% and 99.6% homology with the Weissella koreensis S5623 16S rDNA (Access no. AY035891). They were accordingly identified and named as Weissella koreensis MS1-3 and Weissella koreensis MS1-14, and produced intracellular ornithine at levels of 72 mg/100 g cell F.W. and 105 mg/100 g cell F.W. and extracellular ornithine at levels of 4.5 mg/100 ml and 4.6 mg/100 ml medium, respectively, by culturing in MRS broth supplemented with 1% arginine. High cell growth was maintained in MRS broth with a NaCl concentration of 0-6%. These results show for the first time that Korean natural sea salts contain lactic acid bacteria Weissella koreensis strains having ornithine producing capacity.

  11. Antimicrobial activity of bacteriocin-producing lactic acid bacteria isolated from cheeses and yogurts

    Science.gov (United States)

    2012-01-01

    The biopreservation of foods using bacteriocinogenic lactic acid bacteria (LAB) isolated directly from foods is an innovative approach. The objectives of this study were to isolate and identify bacteriocinogenic LAB from various cheeses and yogurts and evaluate their antimicrobial effects on selected spoilage and pathogenic microorganisms in vitro as well as on a food commodity. LAB were isolated using MRS and M17 media. The agar diffusion bioassay was used to screen for bacteriocin or bacteriocin-like substances (BLS) producing LAB using Lactobacillus sakei and Listeria innocua as indicator organisms. Out of 138 LAB isolates, 28 were found to inhibit these bacteria and were identified as strains of Enterococcus faecium, Streptococcus thermophilus, Lactobacillus casei and Lactobacillus sakei subsp. sakei using 16S rRNA gene sequencing. Eight isolates were tested for antimicrobial activity at 5°C and 20°C against L. innocua, Escherichia coli, Bacillus cereus, Pseudomonas fluorescens, Erwinia carotovora, and Leuconostoc mesenteroides subsp. mesenteroides using the agar diffusion bioassay, and also against Penicillium expansum, Botrytis cinerea and Monilinia frucitcola using the microdilution plate method. The effect of selected LAB strains on L. innocua inoculated onto fresh-cut onions was also investigated. Twenty percent of our isolates produced BLS inhibiting the growth of L. innocua and/or Lact. sakei. Organic acids and/or H2O2 produced by LAB and not the BLS had strong antimicrobial effects on all microorganisms tested with the exception of E. coli. Ent. faecium, Strep. thermophilus and Lact. casei effectively inhibited the growth of natural microflora and L. innocua inoculated onto fresh-cut onions. Bacteriocinogenic LAB present in cheeses and yogurts may have potential to be used as biopreservatives in foods. PMID:22963659

  12. Water Kefir grain as a source of potent dextran producing lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Davidović Slađana Z.

    2015-01-01

    Full Text Available Water kefir is abeverage fermented by a microbial consortium captured in kefir grains. The kefir grains matrix is composed of polysaccharide, primarily dextran, whichis produced by members of the microbial consortium. In this study, we have isolated lactic acid bacteria (LAB from non-commercial water kefir grains (from Belgrade, Serbia and screened for dextran production. Among twelve Lisolates threeproduced slime colonies on modified MRS (mMRS agar containing sucrose instead of glucoseand were presumed to produce dextran. Three LABwere identified based on morphological, physiological and biochemical characteristics and 16S rRNA sequencing as Leuconostoc mesenteroides(strains T1 and T3 and Lactobacillus hilgardii (strain T5. The isolated strains were able to synthesize a substantial amount of dextran in mMRS broth containing 5% sucrose. Maximal yields (11.56, 18.00 and 18.46 g/l were obtained after 16h, 20h and 32h for T1, T3 and T5, respectively. Optimal temperature for dextran production was 23oC for two Leuconostoc mesenteroides strains and 30oC for Lactobacillus hilgardii strain. The produced dextrans were identified based on paper chromatography while the main structure characteristics of purified dextranwere observed by FT-IR spectroscopy. Our study shows that water kefir grains are a natural source of potent dextranproducing LAB. [Projekat Ministarstva nauke Republike Srbije, br. TR 31035

  13. Utilization of Vinegar for Isolation of Cellulose Producing Acetic Acid Bacteria

    Science.gov (United States)

    Aydin, Y. Andelib; Aksoy, Nuran Deveci

    2010-06-01

    Wastes of traditionally fermented Turkish vinegar were used in the isolation of cellulose producing acetic acid bacteria. Waste material was pre-enriched in Hestrin-Schramm medium and microorganisms were isolated by plating dilution series on HS agar plates The isolated strains were subjected to elaborate biochemical and physiological tests for identification. Test results were compared to those of reference strains Gluconacetobacter xylinus DSM 46604, Gluconacetobacter hansenii DSM 5602 and Gluconacetobacter liquefaciens DSM 5603. Seventeen strains, out of which only three were found to secrete the exopolysaccharide cellulose. The highest cellulose yield was recorded as 0.263±0.02 g cellulose L-1 for the strain AS14 which resembled Gluconacetobacter hansenii in terms of biochemical tests.

  14. Isolation, screening and characterization of bacteriocin-producing lactic acid bacteria isolated from traditional fermented food.

    Science.gov (United States)

    El-Shafei, H A; Abd-El-Sabour, H; Ibrahim, N; Mostafa, Y A

    2000-03-01

    100 lactic acid bacterial strains isolated from traditional fermented foods (yoghurt, milk cream, sour dough and milk) were screened for bacteriocin production. Twenty six strains producing a nisin-like bacteriocin were selected. Most of these isolates gave only a narrow inhibitory spectrum, although one showed a broad inhibitory spectrum against the indicator strains tested, this strain was determined as Lactococcus lactis. The influence of several parameters on the fermentative production of nisin by Lactococcus lactis was studied. Production of nisin was optimal at 30 degrees C and in the pH range 5.5-6.3. The effect of different sulphur and nitrogen sources on Lactococcus lactis growth and nisin production was studied. Magnesium sulfate and manganese sulfate were found to be the best sulphur sources while triammonium citrate was the best inorganic nitrogen source and meat extract, peptone and yeast extract were the best organic nitrogen source for nisin production.

  15. High-cell-density fed-batch cultivation of the docosahexaenoic acid producing marine alga Crypthecodinium cohnii

    NARCIS (Netherlands)

    Swaaf, de M.E.; Sijtsma, L.; Pronk, J.T.

    2003-01-01

    The heterotrophic marine alga Crypthecodinium cohnii is known to produce docosahexaenoic acid (DHA), a polyunsaturated fatty acid with food and pharmaceutical applications, during batch cultivation on complex media containing sea salt, yeast extract, and glucose. In the present study, fed-batch cult

  16. Purification and characterisation of an acidic and antifungal chitinase produced by a Streptomyces sp.

    Science.gov (United States)

    Karthik, Narayanan; Binod, Parameswaran; Pandey, Ashok

    2015-01-01

    An extremely acidic extracellular chitinase produced by a Streptomyces sp. was purified 12.44-fold by ammonium sulphate precipitation, ion-exchange chromatography and gel-permeation chromatography and further characterised. The molecular mass of the enzyme was estimated to be about 40 kDa by SDS-PAGE. The optimum pH and temperature of the purified enzyme were pH 2 and 6, and 50 °C respectively. The enzyme showed high stability in the acidic pH range of 2-6 and temperature stability of up to 50 °C. Additionally, the effect of some cations and other chemical compounds on the chitinase activity was studied. The activity of the enzyme was considerably retained under salinity conditions of up to 3%. The Km and Vmax values of the enzyme were determined to be 6.74 mg mL(-1) and 61.3 U mg(-1) respectively using colloidal chitin. This enzyme exhibited antifungal activity against phytopathogens revealing a potential biocontrol application in agriculture.

  17. Trichoderma harzianum Produces a New Thermally Stable Acid Phosphatase, with Potential for Biotechnological Application.

    Directory of Open Access Journals (Sweden)

    Amanda Araújo Souza

    Full Text Available Acid phosphatases (ACPases are produced by a variety of fungi and have gained attention due their biotechnological potential in industrial, diagnosis and bioremediation processes. These enzymes play a specific role in scavenging, mobilization and acquisition of phosphate, enhancing soil fertility and plant growth. In this study, a new ACPase from Trichoderma harzianum, named ACPase II, was purified and characterized as a glycoprotein belonging to the acid phosphatase family. ACPase II presents an optimum pH and temperature of 3.8 and 65 °C, respectively, and is stable at 55 °C for 120 min, retaining 60% of its activity. The enzyme did not require metal divalent ions, but was inhibited by inorganic phosphate and tungstate. Affinity for several phosphate substrates was observed, including phytate, which is the major component of phosphorus in plant foods. The inhibition of ACPase II by tungstate and phosphate at different pH values is consistent with the inability of the substrate to occupy its active site due to electrostatic contacts that promote conformational changes, as indicated by fluorescence spectroscopy. A higher affinity for tungstate rather than phosphate at pH 4.0 was observed, in accordance with its highest inhibitory effect. Results indicate considerable biotechnological potential of the ACPase II in soil environments.

  18. Trichoderma harzianum Produces a New Thermally Stable Acid Phosphatase, with Potential for Biotechnological Application

    Science.gov (United States)

    Souza, Amanda Araújo; Leitão, Vanessa Oliveira; Ramada, Marcelo Henrique; Mehdad, Azadeh; Georg, Raphaela de Castro; Ulhôa, Cirano José; de Freitas, Sonia Maria

    2016-01-01

    Acid phosphatases (ACPases) are produced by a variety of fungi and have gained attention due their biotechnological potential in industrial, diagnosis and bioremediation processes. These enzymes play a specific role in scavenging, mobilization and acquisition of phosphate, enhancing soil fertility and plant growth. In this study, a new ACPase from Trichoderma harzianum, named ACPase II, was purified and characterized as a glycoprotein belonging to the acid phosphatase family. ACPase II presents an optimum pH and temperature of 3.8 and 65°C, respectively, and is stable at 55°C for 120 min, retaining 60% of its activity. The enzyme did not require metal divalent ions, but was inhibited by inorganic phosphate and tungstate. Affinity for several phosphate substrates was observed, including phytate, which is the major component of phosphorus in plant foods. The inhibition of ACPase II by tungstate and phosphate at different pH values is consistent with the inability of the substrate to occupy its active site due to electrostatic contacts that promote conformational changes, as indicated by fluorescence spectroscopy. A higher affinity for tungstate rather than phosphate at pH 4.0was observed, in accordance with its highest inhibitory effect. Results indicate considerable biotechnological potential of the ACPase II in soil environments. PMID:26938873

  19. Sugar-coated: exopolysaccharide producing lactic acid bacteria for food and human health applications.

    Science.gov (United States)

    Ryan, P M; Ross, R P; Fitzgerald, G F; Caplice, N M; Stanton, C

    2015-03-01

    The human enteric microbiome represents a veritable organ relied upon by the host for a range of metabolic and homeostatic functions. Through the production of metabolites such as short chain fatty acids (SCFA), folate, vitamins B and K, lactic acid, bacteriocins, peroxides and exopolysaccharides, the bacteria of the gut microbiome provide nutritional components for colonocytes, liver and muscle cells, competitively exclude potential pathogenic organisms and modulate the hosts immune system. Due to the extensive variation in structure, size and composition, microbial exopolysaccharides represent a useful set of versatile natural ingredients for the food industrial sector, both in terms of their rheological properties and in many cases, their associated health benefits. The exopolysaccharide-producing bacteria that fall within the 35 Lactobacillus and five Bifidobacterium species which have achieved qualified presumption of safety (QPS) and generally recognised as safe (GRAS) status are of particular interest, as their inclusion in food products can avoid considerable scrutiny. In addition, additives commonly utilised by the food industry are becoming unattractive to the consumer, due to the demand for a more 'natural' and 'clean labelled' diet. In situ production of exopolysaccharides by food-grade cultures in many cases confers similar rheological and sensory properties in fermented dairy products, as traditional additives, such as hydrocolloids, collagen and alginate. This review will focus on microbial synthesis of exopolysaccharides, the human health benefits of dietary exopolysaccharides and the technofunctional applications of exopolysaccharide-synthesising microbes in the food industry.

  20. Kinetics of Acid Blue 1 Adsorption from Aqueous Solution by Carbonaceous Substrate Produced from Biotic Precursor

    Institute of Scientific and Technical Information of China (English)

    FAZLULLAH,Khan Bangash; SULTAN,Alam; IRSHAD,Ahmad

    2007-01-01

    Adsorption of acid blue 1 from aqueous solution onto carbonaceous substrate produced from the wood of Paulownia tomentosa was investigated. The samples characterized by FTIR, SEM, EDS and XRD techniques, indicated that the surface functional groups like carboxyl, lactones or phenols and ethers have disappeared at high activation temperature (800 ℃) and as a result porous structure was developed that has a positive effect on the adsorption capacity. Bangham and parabolic diffusion models were applied to the kinetic adsorption data, which show that the adsorption of acid blue 1 was a diffusion controlled process. The reaction rate increased with the increase in temperatures of both the adsorption and activation. Thermodynamic parameters like △E≠, △H≠, △S≠ and △G≠ were calculated from the kinetic data. The negative values of △S≠ reflected the decrease in the disorder of the system at the solid-solution interface during adsorption. Gibbs free energy (△G≠), representing the driving force for the affinity of dye for the carbon surface, increased with the increase in sample activation and the adsorption temperatures.

  1. Mechanistic modeling of biocorrosion caused by biofilms of sulfate reducing bacteria and acid producing bacteria.

    Science.gov (United States)

    Xu, Dake; Li, Yingchao; Gu, Tingyue

    2016-08-01

    Biocorrosion is also known as microbiologically influenced corrosion (MIC). Most anaerobic MIC cases can be classified into two major types. Type I MIC involves non-oxygen oxidants such as sulfate and nitrate that require biocatalysis for their reduction in the cytoplasm of microbes such as sulfate reducing bacteria (SRB) and nitrate reducing bacteria (NRB). This means that the extracellular electrons from the oxidation of metal such as iron must be transported across cell walls into the cytoplasm. Type II MIC involves oxidants such as protons that are secreted by microbes such as acid producing bacteria (APB). The biofilms in this case supply the locally high concentrations of oxidants that are corrosive without biocatalysis. This work describes a mechanistic model that is based on the biocatalytic cathodic sulfate reduction (BCSR) theory. The model utilizes charge transfer and mass transfer concepts to describe the SRB biocorrosion process. The model also includes a mechanism to describe APB attack based on the local acidic pH at a pit bottom. A pitting prediction software package has been created based on the mechanisms. It predicts long-term pitting rates and worst-case scenarios after calibration using SRB short-term pit depth data. Various parameters can be investigated through computer simulation.

  2. Isolation and Selection of Anti-Candida albicans Metabolites Producing Lactic Acid Bacteria from Various Sources

    Directory of Open Access Journals (Sweden)

    Tanes SUNGSRI

    2015-02-01

    Full Text Available Five hundred and fifty-two of lactic acid bacteria (LAB have been isolated and screened from fermented foods, natural sources and dairy effluents on De Mann Rogosa Sharpe (MRS agar. Fifty-one isolates, in the percentile of 9.24, produced the secondary metabolites that could inhibit the growth of Candida albicans BCC6120 by using dual culture overlay assay. The culture broth of LAB, moreover, showed anti-C. albicans activity in acidic condition at pH range of 3.0-5.0 by using agar well diffusion method. Interestingly, the isolate L-47-2 showed much more colonization surrounding the surface of sterile toothpick and test tube when growing in MRS broth. The identification of isolate L-47-2 by morphological and biochemical characteristics using API 50 CHL Test Kit and further confirmed by 16S rRNA gene sequence analysis revealed that isolate L47-2 was similar to Lactobacillus paracasei with 99% nucleotide identity.    

  3. Lasiojasmonates A-C, three jasmonic acid esters produced by Lasiodiplodia sp., a grapevine pathogen.

    Science.gov (United States)

    Andolfi, Anna; Maddau, Lucia; Cimmino, Alessio; Linaldeddu, Benedetto T; Basso, Sara; Deidda, Antonio; Serra, Salvatorica; Evidente, Antonio

    2014-07-01

    In this study, a strain (BL 101) of a species of Lasiodiplodia, not yet formally described, which was isolated from declining grapevine plants showing wedge-shaped cankers, was investigated for its ability to produce in vitro bioactive secondary metabolites. From culture filtrates of this strain three jasmonic acid esters, named lasiojasmonates A-C and 16-O-acetylbotryosphaerilactones A and C were isolated together with (1R,2R)-jasmonic acid, its methyl ester, botryosphaerilactone A, (3S,4R,5R)-4-hydroxymethyl-3,5-dimethyldihydro-2-furanone and (3R,4S)-botryodiplodin. The structures of lasiojasmonates A-C were established by spectroscopic methods as (1R*,2R*,3'S*,4'R*,5'R*)-4-hydroxymethyl-3,5-dimethyldihydro-2-furanone, (1R*,2R*,3'S*,4'R*,5'R*,10'R*,12'R*,13'R*,14'S*) and (1R*,2R*,3'S*,4'R*,5'R*,10'S*,12'R*,13'R*,14'S*)-4-(4-hydroxymethyl-3,5-dimethyltetrahydro-furan-2-yloxymethyl)-3,5-dimethyldihydro-2-furanones jasmonates (1, 4 and 5). The structures of 16-O-acetylbotryosphaerilactones A and C were determined by comparison of their spectral data with those of the corresponding acetyl derivatives obtained by acetylation of botryosphaerilactone A. The metabolites isolated, except 4 and 5, were tested at 1mg/mL on leaves of grapevine cv. Cannonau and cork oak using the leaf puncture assay. They were also tested on detached grapevine leaves at 0.5mg/mL and tomato cuttings at 0.1mg/mL. In all phytotoxic assays only jasmonic acid was found to be active. All metabolites were inactive in the zootoxic assay at 50 μg/mL.

  4. ACTIVITY OF SUPEROXIDE DISMUTASE ENZYME IN YEAST SACCHAROMYCES CEREVISIAE

    Directory of Open Access Journals (Sweden)

    Blažena Lavová

    2014-02-01

    Full Text Available Reactive oxygen species (ROS with reactive nitrogen species (RNS are known to play dual role in biological systems, they can be harmful or beneficial to living systems. ROS can be important mediators of damage to cell structures, including proteins, lipids and nucleic acids termed as oxidative stress. The antioxidant enzymes protect the organism against the oxidative damage caused by active oxygen forms. The role of superoxide dismutase (SOD is to accelerate the dismutation of the toxic superoxide radical, produced during oxidative energy processes, to hydrogen peroxide and molecular oxygen. In this study, SOD activity of three yeast strains Saccharomyces cerevisiae was determined. It was found that SOD activity was the highest (23.7 U.mg-1 protein in strain 612 after 28 hours of cultivation. The lowest SOD activity from all tested strains was found after 56 hours of cultivation of strain Gyöng (0.7 U.mg-1 protein.

  5. Characterization of a novel galactan produced by Weissella confusa KR780676 from an acidic fermented food.

    Science.gov (United States)

    Kavitake, Digambar; Devi, Palanisamy Bruntha; Singh, Sanjay Pratap; Shetty, Prathapkumar Halady

    2016-05-01

    An exopolysaccharide (EPS) producing strain PUFSTM055 isolated from Idli batter (an Indian traditional cereal-legume based fermented food) was identified as Weissella confusa KR780676. The strain was shown to produce 17.2g/L (dry weight) of EPS in 2% sucrose supplemented MRS broth and the EPS was characterized. HPTLC analysis confirmed the presence of galactose monomers, indicating the homopolysaccharide nature of EPS. Fourier-transform infrared spectroscopy and nuclear magnetic resonance analysis revealed that the EPS was found to be a novel linear galactan containing α-(1→6)-linked galactose units. Scanning electron microscopy of the EPS revealed the presence of porous and spongy starch-like granules. Topographical examination of EPS by atomic force microscopy revealed that the EPS formed densely packed mesh-like structure with irregular spherical lumps. The EPS also showed high thermal stability with a degradation temperature of 287.5 °C and melting point at 274.65 °C. EPS was semi-crystalline with crystallinity index of 0.23 and showed 100% water solubility index. These characteristics of the EPS would make it a promising hydrocolloid for food industries as bio-thickeners, stabilizers and also as an encapsulating material for delivery of food bioactive compounds. This is the first study reporting the galactan compose of the EPS from lactic acid bacteria.

  6. Characterization of some bacteriocins produced by lactic acid bacteria isolated from fermented foods.

    Science.gov (United States)

    Grosu-Tudor, Silvia-Simona; Stancu, Mihaela-Marilena; Pelinescu, Diana; Zamfir, Medana

    2014-09-01

    Lactic acid bacteria (LAB) isolated from different sources (dairy products, fruits, fresh and fermented vegetables, fermented cereals) were screened for antimicrobial activity against other bacteria, including potential pathogens and food spoiling bacteria. Six strains have been shown to produce bacteriocins: Lactococcus lactis 19.3, Lactobacillus plantarum 26.1, Enterococcus durans 41.2, isolated from dairy products and Lactobacillus amylolyticus P40 and P50, and Lactobacillus oris P49, isolated from bors. Among the six bacteriocins, there were both heat stable, low molecular mass polypeptides, with a broad inhibitory spectrum, probably belonging to class II bacteriocins, and heat labile, high molecular mass proteins, with a very narrow inhibitory spectrum, most probably belonging to class III bacteriocins. A synergistic effect of some bacteriocins mixtures was observed. We can conclude that fermented foods are still important sources of new functional LAB. Among the six characterized bacteriocins, there might be some novel compounds with interesting features. Moreover, the bacteriocin-producing strains isolated in our study may find applications as protective cultures.

  7. Ciprofloxacin suppresses Cyp3a in mouse liver by reducing lithocholic acid-producing intestinal flora.

    Science.gov (United States)

    Toda, Takahiro; Ohi, Kanna; Kudo, Toshiyuki; Yoshida, Tomoyuki; Ikarashi, Nobutomo; Ito, Kiyomi; Sugiyama, Kiyoshi

    2009-01-01

    Ciprofloxacin (CPX), a new quinolone antibiotic, is reported to reduce CYP3A expression in the liver when administered to rats. The present study investigates whether the reduction in intestinal flora is involved in this reduction of CYP3A. While hepatic Cyp3a11 expression and triazolam metabolic activity were significantly reduced by CPX treatment of SPF mice, no significant changes were seen by CPX treatment of germ-free (GF) mice. Lithocholic acid (LCA)-producing bacteria in the feces as well as hepatic level of taurine conjugate of LCA were significantly reduced in CPX-treated SPF mice. Cyp3a11 expression in GF mice was significantly elevated when treated with LCA, known as an activator of fernesoid X receptor and pregnane X receptor. These results indicate that antibiotics such as CPX, having antimicrobial spectrums against LCA-producing bacteria, possibly cause decrease in LCA in the liver, resulting in lower CYP3A expression. The intestinal flora is reported to be altered also by stress, disease and age etc. The findings of the present study suggest that these changes in intestinal flora may modify CYP expression and contribute to individual differences in pharmacokinetics.

  8. Analysis of microbial community variation during the mixed culture fermentation of agricultural peel wastes to produce lactic acid.

    Science.gov (United States)

    Liang, Shaobo; Gliniewicz, Karol; Gerritsen, Alida T; McDonald, Armando G

    2016-05-01

    Mixed cultures fermentation can be used to convert organic wastes into various chemicals and fuels. This study examined the fermentation performance of four batch reactors fed with different agricultural (orange, banana, and potato (mechanical and steam)) peel wastes using mixed cultures, and monitored the interval variation of reactor microbial communities with 16S rRNA genes using Illumina sequencing. All four reactors produced similar chemical profile with lactic acid (LA) as dominant compound. Acetic acid and ethanol were also observed with small fractions. The Illumina sequencing results revealed the diversity of microbial community decreased during fermentation and a community of largely lactic acid producing bacteria dominated by species of Lactobacillus developed.

  9. Antibacterial Activity of Selected Standard Strains of Lactic Acid Bacteria Producing Bacteriocins – Pilot Study

    Directory of Open Access Journals (Sweden)

    Malgorzata Bodaszewska-Lubas

    2012-10-01

    Full Text Available  Introduction:In this paper, an attempt was made to evaluate the antibacterial potential of standard strains of lactic acid bacteria (LAB producing bacteriocins of various classes, thus demonstrating various mechanisms of cell membrane damages against the Streptococcus agalactiae strains (Group B Streptococcus, GBS, depending on surface polysaccharides and surface alpha-like protein genes.Materials/Methods:Antimicrobial property of the strains of L. plantarum C 11, L. sakei DSMZ 6333, and L. lactis ATCC 11454 producing bacteriocins: JK and EF plantaricins, sakacin and nisin, respectively, against the GBS strains was evaluated. The chosen to the study GBS strains were represented by serotypes Ia, Ib, II, III, V and they had bca, epsilon, rib, alp2 or alp3 alpha-like protein genes. The experiment was conducted by means of suspension culture and the bacteria count was determined using the serial dilution method.Results:A great ability of L. plantarum C 11 strain was proven to inhibit the GBS growth. The strain of L. sakei DSMZ 6333 did not demonstrate any ability to inhibit the growth of GBS, whereas L. lactis ATCC 11454 inhibited the growth of S. agalactiae indicator strains to a minor extent. Statistically significant differences were demonstrated between the GBS strains representing various serotypes against the antimicrobial activity of model LAB strains. The least sensitive to the activity of bacteriocins were the strains representing serotypes Ib and III, whereas the strains representing serotype II were the most sensitive. The sensitivity of the GBS strains to the antimicrobial activity of LAB was not dependent on alpha-like protein genes.Discussion:Among the LAB standard strains producing bacteriocins, the strongest antimicrobial property was observed in the strain of L. plantarum C 11. Because of the generally known and verified strong antagonistic property of the strains of L. plantarum species against indicator bacteria, it is necessary

  10. Plums (Prunus domestica L.) are a good source of yeasts producing organic acids of industrial interest from glycerol.

    Science.gov (United States)

    García-Fraile, Paula; Silva, Luís R; Sánchez-Márquez, Salud; Velázquez, Encarna; Rivas, Raúl

    2013-08-15

    The production of organic acids from several yeasts isolated from mature plums on media containing glycerol as carbon source was analysed by HPLC-UV. The yeasts isolated were identified by sequencing the 5.8S internal transcribed spacer as Pichia fermentans, Wickerhamomyces anomalus and Candida oleophila. The organic acid profiles of these strains comprise acetic, citric, succinic and malic acids that qualitatively and quantitatively vary between different species as well as among strains from the same species. The production from glycerol of succinic, acetic, citric, malic and oxalic acids from C. oleophila and W. anomalus, and that of succinic, oxalic and acetic acids by P. fermentans is reported for the first time in this work, as is the production of oxalic acid from glycerol in yeasts. Our results also showed that mature fruits can be a good source of new yeasts able to metabolise glycerol, producing different organic acids with industrial and biotechnological interest.

  11. KINETIKA FERMENTASI ASAM ASETAT (VINEGAR OLEH BAKTERI Acetobacter aceti B 127 DARI ETANOL HASIL FERMENTASI LIMBAH CAIR PULP KAKAO [Kinetics of Acetic Acid (Vinegar Fermentation By Acetobacter aceti B127 from Ethanol Produced by Fermentation of Liquid Waste of Cacao Pulp

    Directory of Open Access Journals (Sweden)

    M. Supli Effendi

    2002-08-01

    Full Text Available Acetic acid concentration is one of vinegar’s quality parameter. Acetic acid concentration in vinegar is influenced by the activity of acetic acid bacteria. This research studied the kinetics of anaerobic fermentation of liquid waste of cacao pulp by Saccharomyces cerevisiae R60 to produce ethanol and the kinetics of acetic acid fermentation from ethanol by Acetobacter aceti B127. The kinetics of acetic acid fermentation from ethanol by Acetobacter aceti B127 can be used as a basic of bioprocess design for aerobic fermentation in general and acetic acid fermentation from ethanol by Acetobacter aceti B127 in particular. Fermentation medium used was liquid waste of cocoa pulp with sugar content of 12.85%, and the addition of sucrosa and urea. The parameter observed was growth of Saccharomyces cerevisiae R60 and Acetobacter aceti B127, and chemical analysis including concentration of ethanol, total sugar and acetic acid, content. The research result showed that the  value was 0.048 hour-1, Y P was 0.676, Qp value was 0.033 hour-, and KLa value was 0.344, QO2.Cx value was 0.125 (mgO2L-1jam-1, Y X was s O2 0.378 (x 108selmL-1g-1¬¬O2, and dCT was 0.150 mgL-1hour-1. Concentration of acetic acid in the product was 4.24% or 42.4 gL-1

  12. Antimicrobial and immune modulatory effects of lactic acid and short chain fatty acids produced by vaginal microbiota associated with eubiosis and bacterial vaginosis

    Directory of Open Access Journals (Sweden)

    Muriel eAldunate

    2015-06-01

    Full Text Available Lactic acid and short chain fatty acids (SCFAs produced by vaginal microbiota have reported antimicrobial and immune modulatory activities indicating their potential as biomarkers of disease and/or disease susceptibility. In asymptomatic women of reproductive-age the vaginal microbiota is comprised of lactic acid-producing bacteria that are primarily responsible for the production of lactic acid present at ~110 mM and acidifying the vaginal milieu to pH ~3.5. In contrast, bacterial vaginosis (BV, a dysbiosis of the vaginal microbiota, is characterized by decreased lactic acid-producing microbiota and increased diverse anaerobic bacteria accompanied by an elevated pH>4.5. BV is also characterized by a dramatic loss of lactic acid and greater concentrations of mixed SCFAs including acetate, propionate, butyrate and succinate. Notably women with lactic acid-producing microbiota have more favorable reproductive and sexual health outcomes compared to women with BV. Regarding the latter, BV is associated with increased susceptibility to sexually transmitted infections (STIs including HIV. In vitro studies demonstrate that lactic acid produced by vaginal microbiota has microbicidal and virucidal activities that may protect against STIs and endogenous opportunistic bacteria as well as immune modulatory properties that require further characterization with regard to their effects on the vaginal mucosa. In contrast, BV-associated SCFAs have far less antimicrobial activity with the potential to contribute to a pro-inflammatory vaginal environment. Here we review the composition of lactic acid and SCFAs in respective states of eubiosis (non-BV or dysbiosis (BV, their effects on susceptibility to bacterial/viral STIs and whether they have inherent microbicidal/virucidal and immune modulatory properties. We also explore their potential as biomarkers for the presence and/or increased susceptibility to STIs.

  13. Antimicrobial and immune modulatory effects of lactic acid and short chain fatty acids produced by vaginal microbiota associated with eubiosis and bacterial vaginosis.

    Science.gov (United States)

    Aldunate, Muriel; Srbinovski, Daniela; Hearps, Anna C; Latham, Catherine F; Ramsland, Paul A; Gugasyan, Raffi; Cone, Richard A; Tachedjian, Gilda

    2015-01-01

    Lactic acid and short chain fatty acids (SCFAs) produced by vaginal microbiota have reported antimicrobial and immune modulatory activities indicating their potential as biomarkers of disease and/or disease susceptibility. In asymptomatic women of reproductive-age the vaginal microbiota is comprised of lactic acid-producing bacteria that are primarily responsible for the production of lactic acid present at ~110 mM and acidifying the vaginal milieu to pH ~3.5. In contrast, bacterial vaginosis (BV), a dysbiosis of the vaginal microbiota, is characterized by decreased lactic acid-producing microbiota and increased diverse anaerobic bacteria accompanied by an elevated pH>4.5. BV is also characterized by a dramatic loss of lactic acid and greater concentrations of mixed SCFAs including acetate, propionate, butyrate, and succinate. Notably women with lactic acid-producing microbiota have more favorable reproductive and sexual health outcomes compared to women with BV. Regarding the latter, BV is associated with increased susceptibility to sexually transmitted infections (STIs) including HIV. In vitro studies demonstrate that lactic acid produced by vaginal microbiota has microbicidal and virucidal activities that may protect against STIs and endogenous opportunistic bacteria as well as immune modulatory properties that require further characterization with regard to their effects on the vaginal mucosa. In contrast, BV-associated SCFAs have far less antimicrobial activity with the potential to contribute to a pro-inflammatory vaginal environment. Here we review the composition of lactic acid and SCFAs in respective states of eubiosis (non-BV) or dysbiosis (BV), their effects on susceptibility to bacterial/viral STIs and whether they have inherent microbicidal/virucidal and immune modulatory properties. We also explore their potential as biomarkers for the presence and/or increased susceptibility to STIs.

  14. Antifungal hydroxy fatty acids produced during sourdough fermentation: microbial and enzymatic pathways, and antifungal activity in bread.

    Science.gov (United States)

    Black, Brenna A; Zannini, Emanuele; Curtis, Jonathan M; Gänzle, Michael G

    2013-03-01

    Lactobacilli convert linoleic acid to hydroxy fatty acids; however, this conversion has not been demonstrated in food fermentations and it remains unknown whether hydroxy fatty acids produced by lactobacilli have antifungal activity. This study aimed to determine whether lactobacilli convert linoleic acid to metabolites with antifungal activity and to assess whether this conversion can be employed to delay fungal growth on bread. Aqueous and organic extracts from seven strains of lactobacilli grown in modified De Man Rogosa Sharpe medium or sourdough were assayed for antifungal activity. Lactobacillus hammesii exhibited increased antifungal activity upon the addition of linoleic acid as a substrate. Bioassay-guided fractionation attributed the antifungal activity of L. hammesii to a monohydroxy C(18:1) fatty acid. Comparison of its antifungal activity to those of other hydroxy fatty acids revealed that the monohydroxy fraction from L. hammesii and coriolic (13-hydroxy-9,11-octadecadienoic) acid were the most active, with MICs of 0.1 to 0.7 g liter(-1). Ricinoleic (12-hydroxy-9-octadecenoic) acid was active at a MIC of 2.4 g liter(-1). L. hammesii accumulated the monohydroxy C(18:1) fatty acid in sourdough to a concentration of 0.73 ± 0.03 g liter(-1) (mean ± standard deviation). Generation of hydroxy fatty acids in sourdough also occurred through enzymatic oxidation of linoleic acid to coriolic acid. The use of 20% sourdough fermented with L. hammesii or the use of 0.15% coriolic acid in bread making increased the mold-free shelf life by 2 to 3 days or from 2 to more than 6 days, respectively. In conclusion, L. hammesii converts linoleic acid in sourdough and the resulting monohydroxy octadecenoic acid exerts antifungal activity in bread.

  15. Bile Acid Responses in Methane and Non-Methane Producers to Standard Breakfast Meals

    Science.gov (United States)

    Bile acids and their conjugates are important regulators of glucose homeostasis. Previous research has revealed the ratio of cholic acid to deoxycholic acid to affect insulin resistance in humans. Bile acid de-conjugation and intestinal metabolism depend on gut microbes which may be affected by hos...

  16. The interactions between humic acids and Pluronic F127 produce nanoparticles useful for pharmaceutical applications

    Energy Technology Data Exchange (ETDEWEB)

    Melo, Bruna Alice Gomes de; Motta, Fernanda Lopes; Santana, Maria Helena Andrade, E-mail: mariahelena.santana@gmail.com [University of Campinas, Development of Biotechnological Processes Laboratory, School of Chemical Engineering (Brazil)

    2015-10-15

    Humic acids (HAs) are macromolecules composed of a large variety of functional groups including phenols and carboxylic acids, which have anti-inflammatory and antioxidant properties. HAs are completely soluble in aqueous medium in alkaline conditions only. At neutral pH, the protonation of the OH/OOH groups causes the formation of micelle-like structures containing a hydrophobic core. Pluronic F127 (PF127) is a nonionic and non-toxic block copolymer with surfactant properties, which are able to interact with HAs through hydrophobic interactions. In this work, these interactions were studied to determine the potential of HA–PF127 structures for pharmaceutical applications. The HAs used was composed of phenol (15.92 %), carboxylic (13.70 %), and other aromatic groups as characterized by {sup 13}C NMR, GC–MS, and FTIR. Initially, the HA–PF127 interactions were identified by a fivefold decrease in the CMC of PF127. The effects of the HA:PF127 molar ratio were studied by adding naturally occurring HAs to PF127 dispersions under mechanical stirring. The highest ratios, 1:8 and 1:80, favored the formation of submicellar aggregates of approximately 100 nm and zeta potentials of −28.37 and −30.23 mV, respectively. HA–PF127 structures were spherical, with a polydispersity of approximately 0.43. These results show that the interactions between HAs and PF127 produce stable nanoparticles. These nanoparticles may be used as a carrier for hydrophobic bioactives and as an antioxidant or anti-inflammatory agent. To the best of our knowledge, this work is the first attempt to develop HA–PF127 nanoparticles.

  17. The interactions between humic acids and Pluronic F127 produce nanoparticles useful for pharmaceutical applications

    Science.gov (United States)

    de Melo, Bruna Alice Gomes; Motta, Fernanda Lopes; Santana, Maria Helena Andrade

    2015-10-01

    Humic acids (HAs) are macromolecules composed of a large variety of functional groups including phenols and carboxylic acids, which have anti-inflammatory and antioxidant properties. HAs are completely soluble in aqueous medium in alkaline conditions only. At neutral pH, the protonation of the OH/OOH groups causes the formation of micelle-like structures containing a hydrophobic core. Pluronic F127 (PF127) is a nonionic and non-toxic block copolymer with surfactant properties, which are able to interact with HAs through hydrophobic interactions. In this work, these interactions were studied to determine the potential of HA-PF127 structures for pharmaceutical applications. The HAs used was composed of phenol (15.92 %), carboxylic (13.70 %), and other aromatic groups as characterized by 13C NMR, GC-MS, and FTIR. Initially, the HA-PF127 interactions were identified by a fivefold decrease in the CMC of PF127. The effects of the HA:PF127 molar ratio were studied by adding naturally occurring HAs to PF127 dispersions under mechanical stirring. The highest ratios, 1:8 and 1:80, favored the formation of submicellar aggregates of approximately 100 nm and zeta potentials of -28.37 and -30.23 mV, respectively. HA-PF127 structures were spherical, with a polydispersity of approximately 0.43. These results show that the interactions between HAs and PF127 produce stable nanoparticles. These nanoparticles may be used as a carrier for hydrophobic bioactives and as an antioxidant or anti-inflammatory agent. To the best of our knowledge, this work is the first attempt to develop HA-PF127 nanoparticles.

  18. Glyphosate-based herbicides produce teratogenic effects on vertebrates by impairing retinoic acid signaling.

    Science.gov (United States)

    Paganelli, Alejandra; Gnazzo, Victoria; Acosta, Helena; López, Silvia L; Carrasco, Andrés E

    2010-10-18

    The broad spectrum herbicide glyphosate is widely used in agriculture worldwide. There has been ongoing controversy regarding the possible adverse effects of glyphosate on the environment and on human health. Reports of neural defects and craniofacial malformations from regions where glyphosate-based herbicides (GBH) are used led us to undertake an embryological approach to explore the effects of low doses of glyphosate in development. Xenopus laevis embryos were incubated with 1/5000 dilutions of a commercial GBH. The treated embryos were highly abnormal with marked alterations in cephalic and neural crest development and shortening of the anterior-posterior (A-P) axis. Alterations on neural crest markers were later correlated with deformities in the cranial cartilages at tadpole stages. Embryos injected with pure glyphosate showed very similar phenotypes. Moreover, GBH produced similar effects in chicken embryos, showing a gradual loss of rhombomere domains, reduction of the optic vesicles, and microcephaly. This suggests that glyphosate itself was responsible for the phenotypes observed, rather than a surfactant or other component of the commercial formulation. A reporter gene assay revealed that GBH treatment increased endogenous retinoic acid (RA) activity in Xenopus embryos and cotreatment with a RA antagonist rescued the teratogenic effects of the GBH. Therefore, we conclude that the phenotypes produced by GBH are mainly a consequence of the increase of endogenous retinoid activity. This is consistent with the decrease of Sonic hedgehog (Shh) signaling from the embryonic dorsal midline, with the inhibition of otx2 expression and with the disruption of cephalic neural crest development. The direct effect of glyphosate on early mechanisms of morphogenesis in vertebrate embryos opens concerns about the clinical findings from human offspring in populations exposed to GBH in agricultural fields.

  19. Promising Nucleic Acid Lateral Flow Assay Plus PCR for Shiga Toxin-Producing Escherichia coli.

    Science.gov (United States)

    Terao, Yoshitaka; Takeshita, Kana; Nishiyama, Yasutaka; Morishita, Naoki; Matsumoto, Takashi; Morimatsu, Fumiki

    2015-08-01

    Shiga toxin (Stx)-producing Escherichia coli (STEC) is a frequent cause of foodborne infections, and methods for rapid and reliable detection of STEC are needed. A nucleic acid lateral flow assay (NALFA) plus PCR was evaluated for detecting STEC after enrichment. When cell suspensions of 45 STEC strains, 14 non-STEC strains, and 13 non-E. coli strains were tested with the NALFA plus PCR, all of the STEC strains yielded positive results, and all of the non-STEC and non-E. coli strains yielded negative results. The lower detection limit for the STEC strains ranged from 0.1 to 1 pg of genomic DNA (about 20 to 200 CFU) per test, and the NALFA plus PCR was able to detect Stx1- and Stx2-producing E. coli strains with similar sensitivities. The ability of the NALFA plus PCR to detect STEC in enrichment cultures of radish sprouts, tomato, raw ground beef, and beef liver inoculated with 10-fold serially diluted STEC cultures was comparable to that of a real-time PCR assay (at a level of 100 to 100,000 CFU/ml in enrichment culture). The bacterial inoculation test in raw ground beef revealed that the lower detection limit of the NALFA plus PCR was also comparable to that obtained with a real-time PCR assay that followed the U.S. Department of Agriculture guidelines. Although further evaluation is required, these results suggest that the NALFA plus PCR is a specific and sensitive method for detecting STEC in a food manufacturing plant.

  20. Contribution to the aroma of white wines by controlled Torulaspora delbrueckii cultures in association with Saccharomyces cerevisiae.

    Science.gov (United States)

    Azzolini, Michela; Tosi, Emanuele; Lorenzini, Marilinda; Finato, Fabio; Zapparoli, Giacomo

    2015-02-01

    Although the positive role of non-Saccharomyces yeasts on the overall quality of wine is encouraging research into their oenological potential, current knowledge on the topic is still far from satisfactory. This work analyzes the contribution of starter cultures of Torulaspora delbrueckii, inoculated sequentially with Saccharomyces cerevisiae (multi-starter fermentation), on the fermentation and aromas of two different white style wines, i.e., dry and sweet wines. Chemical analysis of Soave and Chardonnay wines (dry wines) showed that multi-starter fermentation greatly affected the content of several important volatile compounds, including 2-phenylethanol, isoamyl acetate, fatty acid esters, C4-C10 fatty acids and vinylphenols. Moreover, strain-specific contributions have been shown by testing two different T. delbrueckii strains. Evidence of the positive impact of T. delbrueckii activity on wine quality was also demonstrated in Vino Santo, a sweet wine. Due to its low production of acetic acid, this non-Saccharomyces yeast is recommended for the fermentation of high sugar grapes. T. delbrueckii also influenced the content of different variety of chemical groups, including lactones. From a sensory perspective, all wines produced by multi-starter fermentation have greater aromatic intensity and complexity than wines resulting from a monoculture fermentation. These results emphasize the potential of employing T. delbrueckii, in association with S. cerevisiae, for the production of white wines of different styles with improved and enhanced flavour.

  1. Spatial Patterns and Temperature Predictions of Tuna Fatty Acids: Tracing Essential Nutrients and Changes in Primary Producers.

    Science.gov (United States)

    Pethybridge, Heidi R; Parrish, Christopher C; Morrongiello, John; Young, Jock W; Farley, Jessica H; Gunasekera, Rasanthi M; Nichols, Peter D

    2015-01-01

    Fatty acids are among the least understood nutrients in marine environments, despite their profile as key energy components of food webs and that they are essential to all life forms. Presented here is a novel approach to predict the spatial-temporal distributions of fatty acids in marine resources using generalized additive mixed models. Fatty acid tracers (FAT) of key primary producers, nutritional condition indices and concentrations of two essential long-chain (≥C20) omega-3 fatty acids (EFA) measured in muscle of albacore tuna, Thunnus alalunga, sampled in the south-west Pacific Ocean were response variables. Predictive variables were: location, time, sea surface temperature (SST) and chlorophyll-a (Chla), and phytoplankton biomass at time of catch and curved fork length. The best model fit for all fatty acid parameters included fish length and SST. The first oceanographic contour maps of EFA and FAT (FATscapes) were produced and demonstrated clear geographical gradients in the study region. Predicted changes in all fatty acid parameters reflected shifts in the size-structure of dominant primary producers. Model projections show that the supply and availability of EFA are likely to be negatively affected by increases in SST especially in temperate waters where a 12% reduction in both total fatty acid content and EFA proportions are predicted. Such changes will have large implications for the availability of energy and associated health benefits to high-order consumers. Results convey new concerns on impacts of projected climate change on fish-derived EFA in marine systems.

  2. Endophytic Fungi from Frankincense Tree Improves Host Growth and Produces Extracellular Enzymes and Indole Acetic Acid.

    Directory of Open Access Journals (Sweden)

    Abdul Latif Khan

    Full Text Available Boswellia sacra, an economically important frankincense-producing tree found in the desert woodlands of Oman, is least known for its endophytic fungal diversity and the potential of these fungi to produce extracellular enzymes and auxins. We isolated various fungal endophytes belonging to Eurotiales (11.8%, Chaetomiaceae (17.6%, Incertae sadis (29.5%, Aureobasidiaceae (17.6%, Nectriaceae (5.9% and Sporomiaceae (17.6% from the phylloplane (leaf and caulosphere (stem of the tree. Endophytes were identified using genomic DNA extraction, PCR amplification and sequencing the internal transcribed spacer regions, whereas a detailed phylogenetic analysis of the same gene fragment was made with homologous sequences. The endophytic colonization rate was significantly higher in the leaf (5.33% than the stem (0.262%. The Shannon-Weiner diversity index was H' 0.8729, while Simpson index was higher in the leaf (0.583 than in the stem (0.416. Regarding the endophytic fungi's potential for extracellular enzyme production, fluorogenic 4-methylumbelliferone standards and substrates were used to determine the presence of cellulases, phosphatases and glucosidases in the pure culture. Among fungal strains, Penicillum citrinum BSL17 showed significantly higher amounts of glucosidases (62.15±1.8 μM-1min-1mL and cellulases (62.11±1.6 μM-1min-1mL, whereas Preussia sp. BSL10 showed significantly higher secretion of glucosidases (69.4±0.79 μM-1min-1mL and phosphatases (3.46±0.31μM-1min-1mL compared to other strains. Aureobasidium sp. BSS6 and Preussia sp. BSL10 showed significantly higher potential for indole acetic acid production (tryptophan-dependent and independent pathways. Preussia sp. BSL10 was applied to the host B. sacra tree saplings, which exhibited significant improvements in plant growth parameters and accumulation of photosynthetic pigments. The current study concluded that endophytic microbial resources producing extracellular enzymes and auxin

  3. In silico screening for candidate chassis strains of free fatty acid-producing cyanobacteria

    KAUST Repository

    Motwalli, Olaa Amin

    2017-01-05

    Background Finding a source from which high-energy-density biofuels can be derived at an industrial scale has become an urgent challenge for renewable energy production. Some microorganisms can produce free fatty acids (FFA) as precursors towards such high-energy-density biofuels. In particular, photosynthetic cyanobacteria are capable of directly converting carbon dioxide into FFA. However, current engineered strains need several rounds of engineering to reach the level of production of FFA to be commercially viable; thus new chassis strains that require less engineering are needed. Although more than 120 cyanobacterial genomes are sequenced, the natural potential of these strains for FFA production and excretion has not been systematically estimated. Results Here we present the FFA SC (FFASC), an in silico screening method that evaluates the potential for FFA production and excretion of cyanobacterial strains based on their proteomes. A literature search allowed for the compilation of 64 proteins, most of which influence FFA production and a few of which affect FFA excretion. The proteins are classified into 49 orthologous groups (OGs) that helped create rules used in the scoring/ranking of algorithms developed to estimate the potential for FFA production and excretion of an organism. Among 125 cyanobacterial strains, FFASC identified 20 candidate chassis strains that rank in their FFA producing and excreting potential above the specifically engineered reference strain, Synechococcus sp. PCC 7002. We further show that the top ranked cyanobacterial strains are unicellular and primarily include Prochlorococcus (order Prochlorales) and marine Synechococcus (order Chroococcales) that cluster phylogenetically. Moreover, two principal categories of enzymes were shown to influence FFA production the most: those ensuring precursor availability for the biosynthesis of lipids, and those involved in handling the oxidative stress associated to FFA synthesis. Conclusion To

  4. Screening for Glucosyltransferase gene (gtf from exopolysaccahride producing lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Donna M. Ariestanti

    2008-04-01

    Full Text Available Glucosyltransferase (GTF is an enzyme involved in exopolysaccharide (EPS polymer synthesis in microbes. One example of EPS that has been used in pharmaceutical and medical application is dextran. Dextran has been used in conjugated-drug delivery system as matrix. As a group of microbes producing EPS, lactic acid bacteria (LAB have been well reported carrying sucrase genes glucosyltransferase (gtf, as well as fructosyltransferases (ftf. In an attempt to search for novel gtf genes as the aim of this study, LAB collection isolated from local sources yielded from previous study were screened performing PCR using degenerate primers DegFor and DegRev. An approximately 660 base pairs (bp amplicons were obtained by using genomic DNAs of those LAB isolates as templates with conserved region of gtf genes catalytic domain as target. Two out of 20 LAB strains were yielded no amplicon as observed on agarose gel, while one strain exhibited non-specific amplicon DNA bands with sizes other than 660 bp. The two negative ones were isolated from soil obtained from dairy product waste field and from waste of soy sauce from previous study, while the latter was isolated from waste of soy sauce.

  5. Lepromatous leprosy patients produce antibodies that recognise non-bilayer lipid arrangements containing mycolic acids

    Directory of Open Access Journals (Sweden)

    Isabel Baeza

    2012-12-01

    Full Text Available Non-bilayer phospholipid arrangements are three-dimensional structures that form when anionic phospholipids with an intermediate structure of the tubular hexagonal phase II are present in a bilayer of lipids. Antibodies that recognise these arrangements have been described in patients with antiphospholipid syndrome and/or systemic lupus erythematosus and in those with preeclampsia; these antibodies have also been documented in an experimental murine model of lupus, in which they are associated with immunopathology. Here, we demonstrate the presence of antibodies against non-bilayer phospholipid arrangements containing mycolic acids in the sera of lepromatous leprosy (LL patients, but not those of healthy volunteers. The presence of antibodies that recognise these non-bilayer lipid arrangements may contribute to the hypergammaglobulinaemia observed in LL patients. We also found IgM and IgG anti-cardiolipin antibodies in 77% of the patients. This positive correlation between the anti-mycolic-non-bilayer arrangements and anti-cardiolipin antibodies suggests that both types of antibodies are produced by a common mechanism, as was demonstrated in the experimental murine model of lupus, in which there was a correlation between the anti-non-bilayer phospholipid arrangements and anti-cardiolipin antibodies. Antibodies to non-bilayer lipid arrangements may represent a previously unrecognised pathogenic mechanism in LL and the detection of these antibodies may be a tool for the early diagnosis of LL patients.

  6. Antimicrobial peptides targeting Gram-negative pathogens, produced and delivered by lactic acid bacteria.

    Science.gov (United States)

    Volzing, Katherine; Borrero, Juan; Sadowsky, Michael J; Kaznessis, Yiannis N

    2013-11-15

    We present results of tests with recombinant Lactococcus lactis that produce and secrete heterologous antimicrobial peptides with activity against Gram-negative pathogenic Escherichia coli and Salmonella . In an initial screening, the activities of numerous candidate antimicrobial peptides, made by solid state synthesis, were assessed against several indicator pathogenic E. coli and Salmonella strains. Peptides A3APO and Alyteserin were selected as top performers based on high antimicrobial activity against the pathogens tested and on significantly lower antimicrobial activity against L. lactis . Expression cassettes containing the signal peptide of the protein Usp45 fused to the codon-optimized sequence of mature A3APO and Alyteserin were cloned under the control of a nisin-inducible promoter PnisA and transformed into L. lactis IL1403. The resulting recombinant strains were induced to express and secrete both peptides. A3APO- and Alyteserin-containing supernatants from these recombinant L. lactis inhibited the growth of pathogenic E. coli and Salmonella by up to 20-fold, while maintaining the host's viability. This system may serve as a model for the production and delivery of antimicrobial peptides by lactic acid bacteria to target Gram-negative pathogenic bacteria populations.

  7. Characterization of short chain fatty acid microcapsules produced by spray drying

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Maria Ines [Programa de Pos-Graduacao em Ciencia de Alimentos, Instituto de Quimica, Centro de Tecnologia, Bloco A, Universidade Federal do Rio de Janeiro (UFRJ), Ilha do Fundao, Rio de Janeiro (RJ), 21910-900 (Brazil); Andrade, Leonardo R. [Departamento de Histologia e Embriologia, Instituto de Ciencias Biomedicas, CCS, UFRJ, Ilha do Fundao, Rio de Janeiro (RJ), 21941-590 (Brazil); Farina, Marcos [Departamento de Histologia e Embriologia, Instituto de Ciencias Biomedicas, CCS, UFRJ, Ilha do Fundao, Rio de Janeiro (RJ), 21941-590 (Brazil); Rocha-Leao, Maria Helena M. [Programa de Pos-Graduacao em Ciencia de Alimentos, Instituto de Quimica, Centro de Tecnologia, Bloco A, Universidade Federal do Rio de Janeiro (UFRJ), Ilha do Fundao, Rio de Janeiro (RJ), 21910-900 (Brazil) and Departamento de Engenharia Bioquimica, Escola de Quimica, Universidade Federal do Rio de Janeiro (UFRJ), Ilha do Fundao, Rio de Janeiro (RJ) 21910-900 (Brazil)]. E-mail: mhrl@eq.ufrj.br

    2004-11-01

    Microcapsules containing short chain fatty acids (SCFA) were produced by spray drying technique using different proportions of gum arabic and maltodextrin as wall materials. Proportions of 5% and 10% of gum arabic and maltodextrin isolated, and a mixture of 5% of maltodextrin and 5% of gum arabic were added to samples of fermented permeate containing SCFA, and spray dried. The microstructure of microcapsules was studied by scanning electron microscopy (SEM) and the size distribution was obtained by laser diffraction. SEM observations showed that the microcapsules structures were affected by type and proportion of wall material tested. Most of the microcapsules containing gum arabic as wall material had surface dents or invaginations. Microcapsules containing maltodextrin were spherical with few surface dents and some of them had pores. The larger microcapsule sizes were observed in those containing maltodextrin. Our results show that microstructure and size of microcapsules are affected by type and proportion of biomaterial used. The samples containing 5% of maltodextrin and the mixture of 5% of gum arabic with 5% of maltodextrin presented smooth surfaces and homogenous size distributions. The corresponding microcapsules are considered optimal to food industrial uses due to the flowability property. Besides, these capsules were found to present a homogenous distribution of diameters, which may give a homogenous flavor distribution to the food products.

  8. Phosphatidic acid produced by phospholipase D promotes RNA replication of a plant RNA virus.

    Directory of Open Access Journals (Sweden)

    Kiwamu Hyodo

    2015-05-01

    Full Text Available Eukaryotic positive-strand RNA [(+RNA] viruses are intracellular obligate parasites replicate using the membrane-bound replicase complexes that contain multiple viral and host components. To replicate, (+RNA viruses exploit host resources and modify host metabolism and membrane organization. Phospholipase D (PLD is a phosphatidylcholine- and phosphatidylethanolamine-hydrolyzing enzyme that catalyzes the production of phosphatidic acid (PA, a lipid second messenger that modulates diverse intracellular signaling in various organisms. PA is normally present in small amounts (less than 1% of total phospholipids, but rapidly and transiently accumulates in lipid bilayers in response to different environmental cues such as biotic and abiotic stresses in plants. However, the precise functions of PLD and PA remain unknown. Here, we report the roles of PLD and PA in genomic RNA replication of a plant (+RNA virus, Red clover necrotic mosaic virus (RCNMV. We found that RCNMV RNA replication complexes formed in Nicotiana benthamiana contained PLDα and PLDβ. Gene-silencing and pharmacological inhibition approaches showed that PLDs and PLDs-derived PA are required for viral RNA replication. Consistent with this, exogenous application of PA enhanced viral RNA replication in plant cells and plant-derived cell-free extracts. We also found that a viral auxiliary replication protein bound to PA in vitro, and that the amount of PA increased in RCNMV-infected plant leaves. Together, our findings suggest that RCNMV hijacks host PA-producing enzymes to replicate.

  9. Pyrenophoric acid, a phytotoxic sesquiterpenoid penta-2,4-dienoic acid produced by a potential mycoherbicide, Pyrenophora semeniperda.

    Science.gov (United States)

    Masi, Marco; Meyer, Susan; Cimmino, Alessio; Andolfi, Anna; Evidente, Antonio

    2014-04-25

    A new phytotoxic sesquiterpenoid penta-2,4-dienoic acid, named pyrenophoric acid, was isolated from solid wheat seed culture of Pyrenophora semeniperda, a fungal pathogen proposed as a mycoherbicide for biocontrol of cheatgrass (Bromus tectorum) and other annual bromes. These bromes are serious weeds in winter cereals and also on temperate semiarid rangelands. Pyrenophoric acid was characterized as (2Z,4E)-5-[(7S,9S,10R,12R)-3,4-dihydroxy-2,2,6-trimethylcyclohexyl)]-3-methylpenta-2,4-dienoic acid by spectroscopic and chemical methods. The relative stereochemistry of pyrenophoric acid was assigned using 1H,1H couplings and NOESY experiments, while its absolute configuration was determined by applying the advanced Mosher's method. Pyrenophoric acid is structurally quite closely related to the plant growth regulator abscisic acid. When bioassayed in a cheatgrass coleoptile elongation test at 10(-3) M, pyrenophoric acid showed strong phytotoxicity, reducing coleoptile elongation by 51% relative to the control. In a mixture at 10(-4) M, its negative effect on coleoptile elongation was additive with that of cytochalasin B, another phytotoxic compound found in the wheat seed culture extract of this fungus, demonstrating that the extract toxicity observed in earlier studies was due to the combined action of multiple phytotoxic compounds.

  10. Combinatorial metabolic engineering of Saccharomyces cerevisiae for terminal alkene production.

    Science.gov (United States)

    Chen, Binbin; Lee, Dong-Yup; Chang, Matthew Wook

    2015-09-01

    Biological production of terminal alkenes has garnered a significant interest due to their industrial applications such as lubricants, detergents and fuels. Here, we engineered the yeast Saccharomyces cerevisiae to produce terminal alkenes via a one-step fatty acid decarboxylation pathway and improved the alkene production using combinatorial engineering strategies. In brief, we first characterized eight fatty acid decarboxylases to enable and enhance alkene production. We then increased the production titer 7-fold by improving the availability of the precursor fatty acids. We additionally increased the titer about 5-fold through genetic cofactor engineering and gene expression tuning in rich medium. Lastly, we further improved the titer 1.8-fold to 3.7 mg/L by optimizing the culturing conditions in bioreactors. This study represents the first report of terminal alkene biosynthesis in S. cerevisiae, and the abovementioned combinatorial engineering approaches collectively increased the titer 67.4-fold. We envision that these approaches could provide insights into devising engineering strategies to improve the production of fatty acid-derived biochemicals in S. cerevisiae.

  11. Comparison of the boronic acid disk potentiation test and cefepime-clavulanic acid method for the detection of ESBL among AmpC-producing Enterobacteriaceae

    Directory of Open Access Journals (Sweden)

    R M Shoorashetty

    2011-01-01

    Full Text Available Purpose: Extended spectrum β-lactamase (ESBL and AmpC β-lactamase are important mechanisms of betalactam resistance among Enterobacteriaceae . The ESBL confirmation test described by Clinical Laboratory Standards Institute (CLSI is in routine use. This method fails to detect ESBL in the presence of AmpC. Therefore, we compared two different ESBL detection methods against the CLSI confirmatory test. Materials and Methods: A total 200 consecutive clinical isolates of Enterobacteriaceae from various clinical samples were tested for ESBL production using (i CLSI described phenotypic confirmatory test (PCT, (ii boronic acid disk potentiation test and (iii cefepime-CA disk potentiation method. AmpC confirmation was done by a modified three-dimensional test. Results: Among total 200 Enterobacteriaceae isolates, 82 were only ESBL producers, 12 were only AmpC producers, 55 were combined ESBL and AmpC producers, 14 were inducible AmpC producers and 37 isolates did not harboured any enzymes. The CLSI described PCT detected ESBL-producing organisms correctly but failed to detect 36.3% of ESBLs among combined enzyme producers. The boronic acid disk potentiation test reliably detected all ESBL, AmpC, and combined enzyme producers correctly. The cefepime-CA method detected all ESBLs correctly but another method of AmpC detection has to be adopted. Conclusion: The use of boronic acid in disk diffusion testing along with the CLSI described PCT enhances ESBL detection in the presence of AmpC betalactamases.

  12. BIOCHEMICAL CHARACTERISTICS OF LACTIC ACID PRODUCING BACTERIA AND PREPARATION OF CAMEL MILK CHEESE BY USING STARTER CULTURE

    OpenAIRE

    T. Ahmed and R. Kanwal

    2004-01-01

    Lactic acid bacteria (LAB) were isolated from camel milk by culturing the milk on specific media and pure culture was obtained by sub-culturing. Purification of culture was confirmed by Gram’s staining and identified by different biochemical tests. Camel milk contained lactic acid producing bacteria like Streptococci such as S. cremoris and S. lactis and Lactobacilli such as L. acidophilus. L. acidophilus grew more rapidly in camel milk than others as its growth was supported by camel milk...

  13. Gene identification and functional analysis of methylcitrate synthase in citric acid-producing Aspergillus niger WU-2223L.

    Science.gov (United States)

    Kobayashi, Keiichi; Hattori, Takasumi; Honda, Yuki; Kirimura, Kohtaro

    2013-01-01

    Methylcitrate synthase (EC 2.3.3.5; MCS) is a key enzyme of the methylcitric acid cycle localized in the mitochondria of eukaryotic cells and related to propionic acid metabolism. In this study, cloning of the gene mcsA encoding MCS and heterologous expression of it in Escherichia coli were performed for functional analysis of the MCS of citric acid-producing Aspergillus niger WU-2223L. Only one copy of mcsA (1,495 bp) exists in the A. niger WU-2223L chromosome. It encodes a 51-kDa polypeptide consisting of 465 amino acids containing mitochondrial targeting signal peptides. Purified recombinant MCS showed not only MCS activity (27.6 U/mg) but also citrate synthase (EC 2.3.3.1; CS) activity (26.8 U/mg). For functional analysis of MCS, mcsA disruptant strain DMCS-1, derived from A. niger WU-2223L, was constructed. Although A. niger WU-2223L showed growth on propionate as sole carbon source, DMCS-1 showed no growth. These results suggest that MCS is an essential enzyme in propionic acid metabolism, and that the methylcitric acid cycle operates functionally in A. niger WU-2223L. To determine whether MCS makes a contribution to citric acid production, citric acid production tests on DMCS-1 were performed. The amount of citric acid produced from glucose consumed by DMCS-1 in citric acid production medium over 12 d of cultivation was on the same level to that by WU-2223L. Thus it was found that MCS made no contribution to citric acid production from glucose in A. niger WU-2223L, although MCS showed CS activity.

  14. Effects of low-intensity ultrasound on the growth, cell membrane permeability and ethanol tolerance of Saccharomyces cerevisiae.

    Science.gov (United States)

    Dai, Chunhua; Xiong, Feng; He, Ronghai; Zhang, Weiwei; Ma, Haile

    2017-05-01

    Effects of low-intensity ultrasound (at different frequency, treatment time and power) on Saccharomyces cerevisiae in different growth phase were evaluated by the biomass in the paper. In addition, the cell membrane permeability and ethanol tolerance of sonicated Saccharomyces cerevisiae were also researched. The results revealed that the biomass of Saccharomyces cerevisiae increased by 127.03% under the optimum ultrasonic conditions such as frequency 28kHz, power 140W/L and ultrasonic time 1h when Saccharomyces cerevisiae cultured to the latent anaphase. And the membrane permeability of Saccharomyces cerevisiae in latent anaphase enhanced by ultrasound, resulting in the augment of extracellular protein, nucleic acid and fructose-1,6-diphosphate (FDP) contents. In addition, sonication could accelerate the damage of high concentration alcohol to Saccharomyces cerevisiae although the ethanol tolerance of Saccharomyces cerevisiae was not affected significantly by ultrasound.

  15. In situ detoxification of dry dilute acid pretreated corn stover by co-culture of xylose-utilizing and inhibitor-tolerant Saccharomyces cerevisiae increases ethanol production.

    Science.gov (United States)

    Zhu, Jia-Qing; Li, Xia; Qin, Lei; Li, Wen-Chao; Li, Hui-Ze; Li, Bing-Zhi; Yuan, Ying-Jin

    2016-10-01

    Co-culture of xylose-utilizing and inhibitor-tolerant Saccharomyces cerevisiae was developed for bioethanol production from undetoxified pretreated biomass in simultaneously saccharification and co-fermentation (SSCF) process. Glucose accumulation during late fermentation phase in SSCF using xylose-utilizing strain can be eliminated by the introduction of inhibitor-tolerant strain. Effect of different ratios of two strains was investigated and xylose-utilizing strain to inhibitor-tolerant strain ratio of 10:1 (w/w) showed the best xylose consumption and the highest ethanol yield. Inoculating of xylose-utilizing strain at the later stage of SSCF (24-48h) exhibited lower ethanol yield than inoculating at early stage (the beginning 0-12h), probably due to the reduced enzymatic efficiency caused by the unconsumed xylose and oligomeric sugars. Co-culture SSCF increased ethanol concentration by 21.2% and 41.0% comparing to SSCF using individual inhibitor-tolerant and xylose-utilizing strain (increased from 48.5 and 41.7g/L to 58.8g/L), respectively, which suggest this co-culture system was very promising.

  16. Acid hydrolysis of crude tannins from infructescence of Platycarya strobilacea Sieb. et Zucc to produce ellagic acid.

    Science.gov (United States)

    Zhang, Liangliang; Wang, Yongmei; Xu, Man

    2014-01-01

    The infructescence of Platycarya strobilacea Sieb. et Zucc is a well-known traditional medicine in China, Japan and Korea. The infructescence of P. strobilacea Sieb. et Zucc is a rich source of ellagitannins that are composed of ellagic acid (EA) and gallic acid, linked to a sugar moiety. The aim of this study was to prepare EA by acid hydrolysis of crude tannins from the infructescence of P. strobilacea Sieb. et Zucc, and establish a new technological processing method for EA. The natural antioxidant EA was prepared by using the water extraction of infructescence of P. strobilacea Sieb. et Zucc, evaporation, condensation, acid hydrolysis and prepared by the process of crystallisation. The yield percentage of EA from crude EA was more than 20% and the purity of the product was more than 98%, as identified by using HPLC. The structure was identified on the basis of spectroscopic analysis and comparison with authentic compound.

  17. Stochastic modelling of Listeria monocytogenes single cell growth in cottage cheese with mesophilic lactic acid bacteria from aroma producing cultures

    DEFF Research Database (Denmark)

    Østergaard, Nina Bjerre; Christiansen, Lasse Engbo; Dalgaard, Paw

    2015-01-01

    A stochastic model was developed for simultaneous growth of low numbers of Listeria monocytogenes and populations of lactic acid bacteria from the aroma producing cultures applied in cottage cheese. During more than two years, different batches of cottage cheese with aroma culture were analysed...... for pH, lactic acid concentration and initial concentration of lactic acid bacteria. These data and bootstrap sampling were used to represent product variability in the stochastic model. Lag time data were estimated from observed growth data (lactic acid bacteria) and from literature on L. monocytogenes....... 2014. Modelling the effect of lactic acid bacteria from starter- and aroma culture on growth of Listeria monocytogenes in cottage cheese. International Journal of Food Microbiology. 188, 15-25]. Growth of L. monocytogenes single cells, using lag time distributions corresponding to three different...

  18. Glucosamine as carbon source for amino acid-producing Corynebacterium glutamicum.

    Science.gov (United States)

    Uhde, Andreas; Youn, Jung-Won; Maeda, Tomoya; Clermont, Lina; Matano, Christian; Krämer, Reinhard; Wendisch, Volker F; Seibold, Gerd M; Marin, Kay

    2013-02-01

    Corynebacterium glutamicum grows with a variety of carbohydrates and carbohydrate derivatives as sole carbon sources; however, growth with glucosamine has not yet been reported. We isolated a spontaneous mutant (M4) which is able to grow as fast with glucosamine as with glucose as sole carbon source. Glucosamine also served as a combined source of carbon, energy and nitrogen for the mutant strain. Characterisation of the M4 mutant revealed a significantly increased expression of the nagB gene encoding the glucosamine-6P deaminase NagB involved in degradation of glucosamine, as a consequence of a single mutation in the promoter region of the nagAB-scrB operon. Ectopic nagB overexpression verified that the activity of the NagB enzyme is in fact the growth limiting factor under these conditions. In addition, glucosamine uptake was studied, which proved to be unchanged in the wild-type and M4 mutant strains. Using specific deletion strains, we identified the PTS(Glc) transport system to be responsible for glucosamine uptake in C. glutamicum. The affinity of this uptake system for glucosamine was about 40-fold lower than that for its major substrate glucose. Because of this difference in affinity, glucosamine is efficiently taken up only if external glucose is absent or present at low concentrations. C. glutamicum was also examined for its suitability to use glucosamine as substrate for biotechnological purposes. Upon overexpression of the nagB gene in suitable C. glutamicum producer strains, efficient production of both the amino acid L-lysine and the diamine putrescine from glucosamine was demonstrated.

  19. Identification of Bacillus species occurring in Kantong, an acid fermented seed condiment produced in Ghana.

    Science.gov (United States)

    Kpikpi, Elmer Nayra; Thorsen, Line; Glover, Richard; Dzogbefia, Victoria Pearl; Jespersen, Lene

    2014-06-16

    Kantong is a condiment produced in Ghana by the spontaneous fermentation of kapok tree (Ceiba pentandra) seeds with cassava flour as an additive. Fermentation is over a 48h period followed by a drying and a kneading process. Although lactic acid bacteria (LAB) have previously been identified other micro-organisms may also be involved in the fermentation process. In this study we examined the occurrence of aerobic endospore-forming bacteria (AEB) in raw materials, during fermentation and in the final product at 2 production sites in Northern Ghana. Total aerobic mesophilic bacterial counts increased from 5.4±0.1log10CFU/g in the raw materials to 8.9±0.1log10CFU/g in the final products, with the AEB accounting for between 23% and 80% of the total aerobic mesophilic (TAM) counts. A total of 196 AEB were identified at a species/subspecies level by the use of phenotypic tests and genotypic methods including M13-PCR typing, 16S rRNA and gyrA gene sequencing. Bacillus subtilis subsp. subtilis (63% of the AEB), Bacillus safensis (26% of the AEB) and Bacillus amyloliquefaciens subsp. plantarum/Bacillus methylotrophicus (9% of the AEB) were the predominant Bacillus species during fermentation and in the final products. B. amyloliquefaciens/B. methylotrophicus originated from cassava flour, B. safensis from seeds and cassava flour, while the origin of B. subtilis was less clear. Brevibacillus agri and Peanibacillus spp. occurred sporadically. Further investigations are required to elucidate the role of AEB occurring in high numbers, in the fermentation of Kantong.

  20. Esterification with ethanol to produce biodiesel from high acidity raw materials. Kinetic studies and analysis of secondary reactions

    Energy Technology Data Exchange (ETDEWEB)

    Pisarello, M.L.; Dalla Costa, B.; Mendow, G.; Querini, C.A. [Instituto de Investigaciones en Catalisis y Petroquimica (INCAPE)-(FIQ-UNL, CONICET), Santiago del Estero 2654-Santa Fe, S3000AOJ (Argentina)

    2010-09-15

    In this work, the esterification reaction of free fatty acids (FFA) in sunflower oil, coconut oil and concentrated FFA, with ethanol, methanol and ethanol 96%, using homogeneous acid catalysts to produce biodiesel is studied. Kinetic parameters are estimated with a simplified model, and then used to predict the reaction behavior. Reactions other than the reversible esterification are considered to explain the behavior that this system displays. Such reactions are the triglycerides conversion by acid catalyzed transesterification and hydrolysis. In addition, we include kinetic studies of the reaction that occur between the sulphuric acid and methanol (or ethanol), forming mono and dialkylsulphates. This reaction produces water and consumes methanol (or ethanol), and consequently has a direct impact in the esterification reaction rate and equilibrium conversion. The concentration of sulphuric acid decreases to less than 50% of the initial value due to the reaction with the alcohol. A minimum in the acidity due to the free fatty acids as a function of time was clearly observed during the reaction, which has not been reported earlier. This behavior is related to the consecutive reactions that take place during the esterification of FFA in the presence of triglycerides. The phase separation due to the presence of water, which is generated during the reaction, is also studied. (author)

  1. A solvent extraction approach to recover acetic acid from mixed waste acids produced during semiconductor wafer process.

    Science.gov (United States)

    Shin, Chang-Hoon; Kim, Ju-Yup; Kim, Jun-Young; Kim, Hyun-Sang; Lee, Hyang-Sook; Mohapatra, Debasish; Ahn, Jae-Woo; Ahn, Jong-Gwan; Bae, Wookeun

    2009-03-15

    Recovery of acetic acid (HAc) from the waste etching solution discharged from silicon wafer manufacturing process has been attempted by using solvent extraction process. For this purpose 2-ethylhexyl alcohol (EHA) was used as organic solvent. In the pre-treatment stage >99% silicon and hydrofluoric acid was removed from the solution by precipitation. The synthesized product, Na(2)SiF(6) having 98.2% purity was considered of commercial grade having good market value. The waste solution containing 279 g/L acetic acid, 513 g/L nitric acid, 0.9 g/L hydrofluoric acid and 0.030 g/L silicon was used for solvent extraction study. From the batch test results equilibrium conditions for HAc recovery were optimized and found to be 4 stages of extraction at an organic:aqueous (O:A) ratio of 3, 4 stages of scrubbing and 4 stages of stripping at an O:A ratio of 1. Deionized water (DW) was used as stripping agent to elute HAc from organic phase. In the whole batch process 96.3% acetic acid recovery was achieved. Continuous operations were successfully conducted for 100 h using a mixer-settler to examine the feasibility of the extraction system for its possible commercial application. Finally, a complete process flowsheet with material balance for the separation and recovery of HAc has been proposed.

  2. Lycotoxin-1 insecticidal peptide optimized by amino acid scanning mutagenesis and expressed as a coproduct in an ethanologenic Saccharomyces cerevisiae strain.

    Science.gov (United States)

    Hughes, Stephen R; Dowd, Patrick F; Hector, Ronald E; Panavas, Tadas; Sterner, David E; Qureshi, Nasib; Bischoff, Kenneth M; Bang, Sookie S; Mertens, Jeffrey A; Johnson, Eric T; Li, Xin-Liang; Jackson, John S; Caughey, Robert J; Riedmuller, Steven B; Bartolett, Scott; Liu, Siqing; Rich, Joseph O; Farrelly, Philip J; Butt, Tauseef R; Labaer, Joshua; Cotta, Michael A

    2008-09-01

    New methods of safe biological pest control are required as a result of evolution of insect resistance to current biopesticides. Yeast strains being developed for conversion of cellulosic biomass to ethanol are potential host systems for expression of commercially valuable peptides, such as bioinsecticides, to increase the cost-effectiveness of the process. Spider venom is one of many potential sources of novel insect-specific peptide toxins. Libraries of mutants of the small amphipathic peptide lycotoxin-1 from the wolf spider were produced in high throughput using an automated integrated plasmid-based functional proteomic platform and screened for ability to kill fall armyworms, a significant cause of damage to corn (maize) and other crops in the United States. Using amino acid scanning mutagenesis (AASM) we generated a library of mutagenized lycotoxin-1 open reading frames (ORF) in a novel small ubiquitin-like modifier (SUMO) yeast expression system. The SUMO technology enhanced expression and improved generation of active lycotoxins. The mutants were engineered to be expressed at high level inside the yeast and ingested by the insect before being cleaved to the active form (so-called Trojan horse strategy). These yeast strains expressing mutant toxin ORFs were also carrying the xylose isomerase (XI) gene and were capable of aerobic growth on xylose. Yeast cultures expressing the peptide toxins were prepared and fed to armyworm larvae to identify the mutant toxins with greatest lethality. The most lethal mutations appeared to increase the ability of the toxin alpha-helix to interact with insect cell membranes or to increase its pore-forming ability, leading to cell lysis. The toxin peptides have potential as value-added coproducts to increase the cost-effectiveness of fuel ethanol bioproduction.

  3. Isolation and characterization of bacteriocin-producing lactic acid bacteria from ready-to-eat food products.

    Science.gov (United States)

    Kelly, W J; Asmundson, R V; Huang, C M

    1996-12-01

    Lactic acid bacteria isolated from a range of foods sold in ready-to-eat form were screened for bacteriocin production. Twenty-two bacteriocin-producing cultures were isolated from 14 of the 41 foods sampled. Bacteriocin-producing isolates from meat, fish and dairy products were Lactobacillus and Leuconostoc species typically found associated with these products. Most of these isolates gave only a narrow inhibitory spectrum although two showed activity against Listeria monocytogenes. Fruit and vegetable products gave a broader range of organisms but most of the bacteriocin-producing cultures were found to be strains of Lactococcus. Several lactococci produced a nisin-like activity, and showed a broad inhibitory spectrum against the indicator strains tested. The ease with which bacteriocin-producing strains could be isolated implies that they are already being safely consumed in food, and highlights the potential for using bacteriocin-producing cultures for biopreservation, especially in association with minimally processed products.

  4. Amiodarone inhibits the mitochondrial beta-oxidation of fatty acids and produces microvesicular steatosis of the liver in mice

    Energy Technology Data Exchange (ETDEWEB)

    Fromenty, B.; Fisch, C.; Labbe, G.; Degott, C.; Deschamps, D.; Berson, A.; Letteron, P.; Pessayre, D. (Institut National de la Sante et de la Recherche Medicale U24, Clichy (France))

    1990-12-01

    Amiodarone has been shown to produce microvesicular steatosis of the liver in some recipients. We have determined the effects of amiodarone on the mitochondrial oxidation of fatty acids in mice. In vitro, the formation of 14C-acid-soluble beta-oxidation products from (U-14C)palmitic acid by mouse liver mitochondria was decreased by 92% in the presence of 125 microM amiodarone and by 94% in the presence of 125 microM N-desethylamiodarone. Inhibition due to 100 or 150 microM amiodarone persisted in the presence of 5 mM acetoacetate, whereas acetoacetate totally relieved inhibition due to 15 microM rotenone. In vivo, exhalation of (14C)CO2 from (U-14C)palmitic acid was decreased by 31, 40, 58 and 78%, respectively, in mice receiving 19, 25, 50 and 100 mg.kg-1 of amiodarone hydrochloride 1 hr before the administration of (U-14C)palmitic acid. One hour after 100 mg.kg-1, the exhalation of (14C)CO2 from (1-14C)palmitic acid, (1-14C)octanoic acid or (1-14C)butyric acid was decreased by 78, 72 and 53%, respectively. Exhalation of (14C)CO2 from (1-14C)palmitic acid was normal between 6 and 9 hr after administration of 100 mg.kg-1 of amiodarone hydrochloride, but was still inhibited by 71 and 37%, 24 and 48 hr after 600 mg.kg-1. Twenty four hours after the latter dose of amiodarone, hepatic triglycerides were increased by 150%, and there was microvesicular steatosis of the liver. We conclude that amiodarone inhibits the mitochondrial beta-oxidation of fatty acids and produces microvesicular steatosis of the liver in mice.

  5. Gas release-based prescreening combined with reversed-phase HPLC quantitation for efficient selection of high-γ-aminobutyric acid (GABA)-producing lactic acid bacteria.

    Science.gov (United States)

    Wu, Qinglong; Shah, Nagendra P

    2015-02-01

    High γ-aminobutyric acid (GABA)-producing lactobacilli are promising for the manufacture of GABA-rich foods and to synthesize GRAS (generally recognized as safe)-grade GABA. However, common chromatography-based screening is time-consuming and inefficient. In the present study, Korean kimchi was used as a model of lactic acid-based fermented foods, and a gas release-based prescreening of potential GABA producers was developed. The ability to produce GABA by potential GABA producers in de Man, Rogosa, and Sharpe medium supplemented with or without monosodium glutamate was further determined by HPLC. Based on the results, 9 isolates were regarded as high GABA producers, and were further genetically identified as Lactobacillus brevis based on the sequences of 16S rRNA gene. Gas release-based prescreening combined with reversed-phase HPLC confirmation was an efficient and cost-effective method to identify high-GABA-producing LAB, which could be good candidates for probiotics. The GABA that is naturally produced by these high-GABA-producing LAB could be used as a food additive.

  6. Optimization culture medium of Saccharomyces cerevisiae B5 with high ability of producing carbonyl reductase using response surface methodology%响应面法优化高选择性羰基还原酶产生菌Saccharomyces cerevisiae B5的培养基组成

    Institute of Scientific and Technical Information of China (English)

    欧志敏; 杨根生; 王鸿; 林德君

    2008-01-01

    借助于SAS软件,采用部分因子实验设计(FFD)和响应面分析法(RSM),对能够产生高选择性羰基还原酶的菌株Saccharomyces cerevisiae B5进行发酵培养基的优化.部分因子实验设计结果表明葡萄糖、硫酸铵、硫酸镁及磷酸氢二钾为影响Saccharomyces cerevisiae B5产生高选择性羰基还原酶的四个显著性因素.通过响应面分析法,得到最优发酵培养基组成为:葡萄糖29.7 g/L,酵母粉3 g/L,硫酸铵4.784 g/L,无水硫酸镁0.267 2 g/L,K2HPO4·3H2O 1.026 g/L,KH2PO41g/L.在优化的培养基条件下,羰基还原酶活力最高可达1 498.2 U/g.

  7. 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...

  8. KRAFT MILL BIOREFINERY TO PRODUCE ACETIC ACID AND ETHANOL: TECHNICAL ECONOMIC ANALYSIS

    OpenAIRE

    Haibo Mao; Joseph M. Genco; Adriaan van Heiningen; Hemant Pendse

    2010-01-01

    The “near neutral hemicellulose extraction process” involves extraction of hemicellulose using green liquor prior to kraft pulping. Ancillary unit operations include hydrolysis of the extracted carbohydrates using sulfuric acid, removal of extracted lignin, liquid-liquid extraction of acetic acid, liming followed by separation of gypsum, fermentation of C5 and C6 sugars, and upgrading the acetic acid and ethanol products by distillation. The process described here is a variant of the “near n...

  9. Lactobacilli reduce cell cytotoxicity caused by Streptococcus pyogenes by producing lactic acid that degrades the toxic component lipoteichoic acid.

    Science.gov (United States)

    Maudsdotter, Lisa; Jonsson, Hans; Roos, Stefan; Jonsson, Ann-Beth

    2011-04-01

    Lactobacilli are known to prevent colonization by many pathogens; nevertheless, the mechanisms of their protective effect are largely unknown. In this work, we investigated the role of lactobacilli during infection of epithelial cells with group A streptococci (GAS). GAS cause a variety of illnesses ranging from noninvasive disease to more severe invasive infections, such as necrotizing fasciitis and toxic shock-like syndrome. Invasion of deeper tissues is facilitated by GAS-induced apoptosis and cell death. We found that lactobacilli inhibit GAS-induced host cell cytotoxicity and shedding of the complement regulator CD46. Further, survival assays demonstrated that lactic acid secreted by lactobacilli is highly bactericidal toward GAS. In addition, lactic acid treatment of GAS, but not heat killing, prior to infection abolishes the cytotoxic effects against human cells. Since lipoteichoic acid (LTA) of GAS is heat resistant and cytotoxic, we explored the effects of lactic acid on LTA. By applying such an approach, we demonstrate that lactic acid reduces epithelial cell damage caused by GAS by degrading both secreted and cell-bound LTA. Taken together, our experiments reveal a mechanism by which lactobacilli prevent pathogen-induced host cell damage.

  10. Oxidative stability during storage of structured lipids produced from fish oil and caprylic acid

    DEFF Research Database (Denmark)

    Nielsen, Nina Skall; Xu, Xuebing; Timm Heinrich, Maike;

    2004-01-01

    Structured lipids produced by enzymatic or chemical methods for different applications have been receiving considerable attention. The oxidative stability of a randomized structured lipid (RFO), produced by chemical interesterification from fish oil (FO) and tricaprylin, and a specific structured...

  11. 10-oxo-12(Z)-octadecenoic acid, a linoleic acid metabolite produced by gut lactic acid bacteria, potently activates PPARγ and stimulates adipogenesis.

    Science.gov (United States)

    Goto, Tsuyoshi; Kim, Young-Il; Furuzono, Tomoya; Takahashi, Nobuyuki; Yamakuni, Kanae; Yang, Ha-Eun; Li, Yongjia; Ohue, Ryuji; Nomura, Wataru; Sugawara, Tatsuya; Yu, Rina; Kitamura, Nahoko; Park, Si-Bum; Kishino, Shigenobu; Ogawa, Jun; Kawada, Teruo

    2015-04-17

    Our previous study has shown that gut lactic acid bacteria generate various kinds of fatty acids from polyunsaturated fatty acids such as linoleic acid (LA). In this study, we investigated the effects of LA and LA-derived fatty acids on the activation of peroxisome proliferator-activated receptors (PPARs) which regulate whole-body energy metabolism. None of the fatty acids activated PPARδ, whereas almost all activated PPARα in luciferase assays. Two fatty acids potently activated PPARγ, a master regulator of adipocyte differentiation, with 10-oxo-12(Z)-octadecenoic acid (KetoA) having the most potency. In 3T3-L1 cells, KetoA induced adipocyte differentiation via the activation of PPARγ, and increased adiponectin production and insulin-stimulated glucose uptake. These findings suggest that fatty acids, including KetoA, generated in gut by lactic acid bacteria may be involved in the regulation of host energy metabolism.

  12. Retinoic acid primes human dendritic cells to induce gut-homing, IL-10-producing regulatory T cells

    NARCIS (Netherlands)

    Bakdash, G.; Vogelpoel, L.T.; Capel, T.M. van; Kapsenberg, M.L.; Jong, E.C. de

    2015-01-01

    The vitamin A metabolite all-trans retinoic acid (RA) is an important determinant of intestinal immunity. RA primes dendritic cells (DCs) to express CD103 and produce RA themselves, which induces the gut-homing receptors alpha4beta7 and CCR9 on T cells and amplifies transforming growth factor (TGF)-

  13. Xylanases, Cellulases, and Acid Protease Produced by Stenocarpella maydis Grown in Solid-state and Submerged Fermentation

    Directory of Open Access Journals (Sweden)

    Edna María Hernández-Domínguez

    2014-03-01

    Full Text Available Activity levels of extracellular hydrolytic enzymes produced by Stenocarpella maydis, a fungal pathogen of maize, have so far not been reported. Production of xylanase, cellulase, and acid protease by this ascomycete using different culture media in solid-state and submerged fermentation was studied. In solid-state fermentation, polyurethane foam was used as an inert support, and corncob, corn leaves, and broken corn were used as biodegradable supports. The highest xylanase activity was produced in the medium with xylan in both fermentation systems, reaching 18,020 U/L and 19,266 U/L for submerged and solid-state fermentation, respectively. Cellulase production was observed only in the culture medium with carboxymethylcellulose, obtaining values of 7,872 U/L in submerged fermentation and 9,439 U/L in solid-state fermentation. The acid protease was produced only in minimal medium with glucose in acidic pH, reaching the highest levels of activity in SSF (806 U/L. The corncob was the best biodegradable support for the production of xylanases and acid protease. Two isoenzymes of xylanase and cellulase were observed in both fermentation systems, and three isoenzymes of xylanase were produced on the biodegradable supports.

  14. Electrophilic acid gas-reactive fluid, proppant, and process for enhanced fracturing and recovery of energy producing materials

    Science.gov (United States)

    Fernandez, Carlos A.; Heldebrant, David J.; Bonneville, Alain H. R.; Jung, Hun Bok; Carroll, Kenneth

    2016-09-20

    An electrophilic acid gas-reactive fracturing and recovery fluid, proppant, and process are detailed. The fluid expands in volume to provide rapid and controlled increases in pressure that enhances fracturing in subterranean bedrock for recovery of energy-producing materials. Proppants stabilize openings in fractures and fissures following fracturing.

  15. Nematicidal Activity of Kojic Acid Produced by Aspergillus oryzae against Meloidogyne incognita.

    Science.gov (United States)

    Kim, Tae Yoon; Jang, Ja Yeong; Jeon, Sun Jeong; Lee, Hye Won; Bae, Chang-Hwan; Yeo, Joo Hong; Lee, Hyang Burm; Kim, In Seon; Park, Hae Woong; Kim, Jin-Cheol

    2016-08-28

    The fungal strain EML-DML3PNa1 isolated from leaf of white dogwood (Cornus alba L.) showed strong nematicidal activity with juvenile mortality of 87.6% at a concentration of 20% fermentation broth filtrate at 3 days after treatment. The active fungal strain was identified as Aspergillus oryzae, which belongs to section Flavi, based on the morphological characteristics and sequence analysis of the ITS rDNA, calmodulin (CaM), and β-tubulin (BenA) genes. The strain reduced the pH value to 5.62 after 7 days of incubation. Organic acid analysis revealed the presence of citric acid (515.0 mg/kg), malic acid (506.6 mg/kg), and fumaric acid (21.7 mg/kg). The three organic acids showed moderate nematicidal activities, but the mixture of citric acid, malic acid, and fumaric acid did not exhibit the full nematicidal activity of the culture filtrate of EML- DML3PNa1. Bioassay-guided fractionation coupled with (1)H- and (13)C-NMR and EI-MS analyses led to identification of kojic acid as the major nematicidal metabolite. Kojic acid exhibited dose-dependent mortality and inhibited the hatchability of M. incognita, showing EC50 values of 195.2 µg/ml and 238.3 µg/ml, respectively, at 72 h postexposure. These results suggest that A. oryzae EML-DML3PNa1 and kojic acid have potential as a biological control agent against M. incognita.

  16. Functional analysis and transcriptional regulation of two orthologs of ARO10, encoding broad-substrate-specificity 2-oxo-acid decarboxylases, in the brewing yeast Saccharomyces pastorianus CBS1483.

    Science.gov (United States)

    Bolat, Irina; Romagnoli, Gabriele; Zhu, Feibai; Pronk, Jack T; Daran, Jean-Marc

    2013-09-01

    The hybrid genomes of Saccharomyces pastorianus consist of subgenomes similar to those of S. cerevisiae and S. eubayanus, and impact of the genome structure on flavour production and its regulation is poorly understood. This study focuses on ARO10, a 2-oxo-acid decarboxylase involved in production of higher alcohols. In S. pastorianus CBS1483, four ARO10 copies were identified, three resembled S. cerevisiae ARO10 and one S. eubayanus ARO10. Substrate specificities of lager strain (Lg)ScAro10 and LgSeubAro10 were compared by individually expressing them in a pdc1Δ-pdc5Δ-pdc6Δ-aro10Δ-thi3Δ S. cerevisiae strain. Both isoenzymes catalysed decarboxylation of the 2-oxo-acids derived from branched-chain, sulphur-containing amino acids and preferably phenylpyruvate. Expression of both alleles was induced by phenylalanine, however in contrast to the S. cerevisiae strain, the two genes were not induced by leucine. Additionally, LgSeubARO10 showed higher basal expression levels during growth with ammonia. ARO80, which encodes ARO10 transcriptional activator, is located on CHRIV and counts three Sc-like and one Seub-like copies. Deletion of LgSeubARO80 did not affect LgSeubARO10 phenylalanine induction, revealing 'trans' regulation across the subgenomes. ARO10 transcript levels showed a poor correlation with decarboxylase activities. These results provide insights into flavour formation in S. pastorianus and illustrate the complexity of functional characterization in aneuploid strains.

  17. Selective Oxidative Decarboxylation of Amino Acids to Produce Industrially Relevant Nitriles by Vanadium Chloroperoxidase

    NARCIS (Netherlands)

    But, A.; Notre, le J.E.L.; Scott, E.L.; Wever, R.; Sanders, J.P.M.

    2012-01-01

    Industrial nitriles from biomass: Vanadium-chloroperoxidase is successfully used to transform selectively glutamic acid into 3-cyanopropanoic acid, a key intermediate for the synthesis of bio-succinonitrile and bio-acrylonitrile, by using a catalytic amount of a halide salt. This clean oxidative dec

  18. Complete Genome Sequence of Streptomyces clavuligerus F613-1, an Industrial Producer of Clavulanic Acid.

    Science.gov (United States)

    Cao, Guangxiang; Zhong, Chuanqing; Zong, Gongli; Fu, Jiafang; Liu, Zhong; Zhang, Guimin; Qin, Ronghuo

    2016-01-01

    Streptomyces clavuligerus strain F613-1 is an industrial strain with high-yield clavulanic acid production. In this study, the complete genome sequence of S. clavuligerus strain F613-1 was determined, including one linear chromosome and one linear plasmid, carrying numerous sets of genes involving in the biosynthesis of clavulanic acid.

  19. The Interaction between Saccharomyces cerevisiae and Non-Saccharomyces Yeast during Alcoholic Fermentation Is Species and Strain Specific.

    Science.gov (United States)

    Wang, Chunxiao; Mas, Albert; Esteve-Zarzoso, Braulio

    2016-01-01

    The present study analyzes the lack of culturability of different non-Saccharomyces strains due to interaction with Saccharomyces cerevisiae during alcoholic fermentation. Interaction was followed in mixed fermentations with 1:1 inoculation of S. cerevisiae and ten non-Saccharomyces strains. Starmerella bacillaris, and Torulaspora delbrueckii indicated longer coexistence in mixed fermentations compared with Hanseniaspora uvarum and Metschnikowia pulcherrima. Strain differences in culturability and nutrient consumption (glucose, alanine, ammonium, arginine, or glutamine) were found within each species in mixed fermentation with S. cerevisiae. The interaction was further analyzed using cell-free supernatant from S. cerevisiae and synthetic media mimicking both single fermentations with S. cerevisiae and using mixed fermentations with the corresponding non-Saccharomyces species. Cell-free S. cerevisiae supernatants induced faster culturability loss than synthetic media corresponding to the same fermentation stage. This demonstrated that some metabolites produced by S. cerevisiae played the main role in the decreased culturability of the other non-Saccharomyces yeasts. However, changes in the concentrations of main metabolites had also an effect. Culturability differences were observed among species and strains in culture assays and thus showed distinct tolerance to S. cerevisiae metabolites and fermentation environment. Viability kit and recovery analyses on non-culturable cells verified the existence of viable but not-culturable status. These findings are discussed in the context of interaction between non-Saccharomyces and S. cerevisiae.

  20. The Interaction between Saccharomyces cerevisiae and Non-Saccharomyces Yeast during Alcoholic Fermentation is Species and Strain Specific

    Directory of Open Access Journals (Sweden)

    Chunxiao eWang

    2016-04-01

    Full Text Available The present study analyzes the lack of culturability of different non-Saccharomyces strains due to interaction with Saccharomyces cerevisiae during alcoholic fermentation. Interaction was followed in mixed fermentations with 1:1 inoculation of S. cerevisiae and ten non-Saccharomyces strains. Starmerella bacillaris and Torulaspora delbrueckii indicated longer coexistence in mixed fermentations compared with Hanseniaspora uvarum and Metschnikowia pulcherrima. Strain differences in culturability and nutrient consumption (glucose, alanine, ammonium, arginine or glutamine were found within each species in mixed fermentation with S. cerevisiae. The interaction was further analyzed using cell-free supernatant from S. cerevisiae and synthetic media mimicking both single fermentations with S. cerevisiae and using mixed fermentations with the corresponding non-Saccharomyces species. Cell-free S. cerevisiae supernatants induced faster culturability loss than synthetic media corresponding to the same fermentation stage. This demonstrated that some metabolites produced by S. cerevisiae played the main role in the decreased culturability of the other non-Saccharomyces yeasts. However, changes in the concentrations of main metabolites had also an effect. Culturability differences were observed among species and strains in culture assays and thus showed distinct tolerance to S. cerevisiae metabolites and fermentation environment. Viability kit and recovery analyses on non-culturable cells verified the existence of viable but not-culturable status. These findings are discussed in the context of interaction between non-Saccharomyces and S. cerevisiae.

  1. A new alternative to produce gibberellic acid by solid state fermentation

    Directory of Open Access Journals (Sweden)

    Cristine Rodrigues

    2009-11-01

    Full Text Available Gibberellic acid (GA3 is an important hormone, which controls plant's growth and development. Solid State Fermentation (SSF allows the use of agro-industrial residues reducing the production costs. The screening of strains (four of Gibberella fujikuoroi and one of Fusarium moniliforme and substrates (citric pulp, soy bran, sugarcane bagasse, soy husk, cassava bagasse and coffee husk and inoculum preparation study were conducted in order to evaluate the best conditions to produce GA3 by SSF. Fermentation assays were carried out in erlenmeyers flasks at 29°C, with initial moisture of 75-80%. Different medium for inoculum production were tested in relation to cells viability and GA3 production by SSF. F. moniliforme LPB 03 and citric pulp were chosen for GA3 production. The best medium for inoculum production was citric pulp extract supplemented with sucrose. GA3 production by SSF reached 5.9 g /kg of dry CP after 3 days of fermentation.O ácido giberélico (GA3 é um importante hormônio vegetal. A fermentação no estado sólido (FES utiliza resíduos agro-industriais reduzindo os custos de produção. Neste trabalho a seleção de cepas (quatro de Gibberella fujikuoroi e uma de Fusarium moniliforme e substratos (polpa cítrica, casca de soja, bagaço de cana, farelo de soja, bagaço de mandioca e casca de café e o estudo da preparação do inóculo foram conduzidos para otimizar as condições de produção de GA3 por FES. Os ensaios foram realizados em frascos de erlenmeyer a 29°C, com umidade inicial de 75-80%. Diferentes meios para a produção do inóculo foram testados em relação à viabilidade das células e produção de GA3 por FES. F. moniliforme LPB03 e polpa cítrica foram escolhidos. O melhor meio para a produção de inóculo foi o extrato de polpa cítrica. A produção por FES alcançou 5.8 g de GA3/kg de polpa cítrica após 3 dias de fermentação.

  2. Spatial Patterns and Temperature Predictions of Tuna Fatty Acids: Tracing Essential Nutrients and Changes in Primary Producers.

    Directory of Open Access Journals (Sweden)

    Heidi R Pethybridge

    Full Text Available Fatty acids are among the least understood nutrients in marine environments, despite their profile as key energy components of food webs and that they are essential to all life forms. Presented here is a novel approach to predict the spatial-temporal distributions of fatty acids in marine resources using generalized additive mixed models. Fatty acid tracers (FAT of key primary producers, nutritional condition indices and concentrations of two essential long-chain (≥C20 omega-3 fatty acids (EFA measured in muscle of albacore tuna, Thunnus alalunga, sampled in the south-west Pacific Ocean were response variables. Predictive variables were: location, time, sea surface temperature (SST and chlorophyll-a (Chla, and phytoplankton biomass at time of catch and curved fork length. The best model fit for all fatty acid parameters included fish length and SST. The first oceanographic contour maps of EFA and FAT (FATscapes were produced and demonstrated clear geographical gradients in the study region. Predicted changes in all fatty acid parameters reflected shifts in the size-structure of dominant primary producers. Model projections show that the supply and availability of EFA are likely to be negatively affected by increases in SST especially in temperate waters where a 12% reduction in both total fatty acid content and EFA proportions are predicted. Such changes will have large implications for the availability of energy and associated health benefits to high-order consumers. Results convey new concerns on impacts of projected climate change on fish-derived EFA in marine systems.

  3. Effect of purified β-glucans derived from Laminaria digitata, Laminaria hyperborea and Saccharomyces cerevisiae on piglet performance, selected bacterial populations, volatile fatty acids and pro-inflammatory cytokines in the gastrointestinal tract of pigs.

    Science.gov (United States)

    Sweeney, T; Collins, C B; Reilly, P; Pierce, K M; Ryan, M; O'Doherty, J V

    2012-10-01

    β-Glucans have been identified as natural biomolecules with immunomodulatory activity. The first objective of the present study was to compare the effects of purified β-glucans derived from Laminaria digitata, L. hyperborea and Saccharomyces cerevisiae on piglet performance, selected bacterial populations and intestinal volatile fatty acid (VFA) production. The second aim was to compare the gene expression profiles of the markers of pro- and anti-inflammation in both unchallenged and lipopolysaccharide (LPS)-challenged ileal and colonic tissues. β-Glucans were included at 250 mg/kg in the diets. The β-glucans derived from L. hyperborea, L. digitata and S. cerevisiae all reduced the Enterobacteriaceae population (P0·05) in the ileum and colon. There was a significant interaction between gastrointestinal region and β-glucan source in the expression of cytokine markers, IL-1α (yeast sources reduce Enterobacteriaceae counts and pro-inflammatory markers in the colon, though the mechanisms of action may be different between the soluble and insoluble fibre sources.

  4. Synthesis and emulsifying properties of carbohydrate fatty acid esters produced from Agave tequilana fructans by enzymatic acylation.

    Science.gov (United States)

    Casas-Godoy, Leticia; Arrizon, Javier; Arrieta-Baez, Daniel; Plou, Francisco J; Sandoval, Georgina

    2016-08-01

    Carbohydrate fatty acid esters are non-ionic surfactants with a broad spectrum of applications. These molecules are generally synthesized using short carbohydrates or linear fructans; however in this research carbohydrate fatty acid esters were produced for the first time with branched fructans from Agave tequilana. Using immobilized lipases we successfully acylated A. tequilana fructans with vinyl laurate, obtaining products with different degrees of polymerization (DP). Lipozyme 435 was the most efficient lipase to catalyze the transesterification reaction. HPLC and ESI-MS analysis proved the presence of a mixture of acylated products as a result of the chemical complexity of fructans in the A. tequilana. The ESI-MS spectra showed a molecular mass shift between 183 and 366g/mol for fructooligosaccharides with a DP lower than 6, which indicated the presence of Agave fructans that had been mono- and diacylated with lauric acid. The carbohydrate fatty acid esters (CFAE) obtained showed good emulsifying properties in W/O emulsions.

  5. 10-oxo-12(Z)-octadecenoic acid, a linoleic acid metabolite produced by gut lactic acid bacteria, potently activates PPARγ and stimulates adipogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Tsuyoshi, E-mail: tgoto@kais.kyoto-u.ac.jp [Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011 (Japan); Research Unit for Physiological Chemistry, The Center for the Promotion of Interdisciplinary Education and Research, Kyoto University (Japan); Kim, Young-Il; Furuzono, Tomoya [Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011 (Japan); Takahashi, Nobuyuki [Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011 (Japan); Research Unit for Physiological Chemistry, The Center for the Promotion of Interdisciplinary Education and Research, Kyoto University (Japan); Yamakuni, Kanae; Yang, Ha-Eun; Li, Yongjia [Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011 (Japan); Ohue, Ryuji [Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011 (Japan); Research Unit for Physiological Chemistry, The Center for the Promotion of Interdisciplinary Education and Research, Kyoto University (Japan); Nomura, Wataru [Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji 611-0011 (Japan); Sugawara, Tatsuya [Laboratory of Marine Bioproducts Technology, Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502 (Japan); Yu, Rina [Department of Food Science and Nutrition, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Kitamura, Nahoko [Laboratory of Fermentation Physiology and Applied Microbiology, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502 (Japan); and others

    2015-04-17

    Our previous study has shown that gut lactic acid bacteria generate various kinds of fatty acids from polyunsaturated fatty acids such as linoleic acid (LA). In this study, we investigated the effects of LA and LA-derived fatty acids on the activation of peroxisome proliferator-activated receptors (PPARs) which regulate whole-body energy metabolism. None of the fatty acids activated PPARδ, whereas almost all activated PPARα in luciferase assays. Two fatty acids potently activated PPARγ, a master regulator of adipocyte differentiation, with 10-oxo-12(Z)-octadecenoic acid (KetoA) having the most potency. In 3T3-L1 cells, KetoA induced adipocyte differentiation via the activation of PPARγ, and increased adiponectin production and insulin-stimulated glucose uptake. These findings suggest that fatty acids, including KetoA, generated in gut by lactic acid bacteria may be involved in the regulation of host energy metabolism. - Highlights: • Most LA-derived fatty acids from gut lactic acid bacteria potently activated PPARα. • Among tested fatty acids, KetoA and KetoC significantly activated PPARγ. • KetoA induced adipocyte differentiation via the activation of PPARγ. • KetoA enhanced adiponectin production and glucose uptake during adipogenesis.

  6. High temperature dilute phosphoric acid pretreatment of corn stover for furfural and ethanol production

    Science.gov (United States)

    Furfural was produced from corn stover by one stage pretreatment process using dilute H3PO4 and solid residues following furfural production were used for ethanol production by Saccharomyces cerevisiae NRRL- Y2034. A series of experiments were conducted at varied temperatures (140-200 oC) and acid ...

  7. Rosmarinic acid is a homoserine lactone mimic produced by plants that activates a bacterial quorum-sensing regulator.

    Science.gov (United States)

    Corral-Lugo, Andrés; Daddaoua, Abdelali; Ortega, Alvaro; Espinosa-Urgel, Manuel; Krell, Tino

    2016-01-05

    Quorum sensing is a bacterial communication mechanism that controls genes, enabling bacteria to live as communities, such as biofilms. Homoserine lactone (HSL) molecules function as quorum-sensing signals for Gram-negative bacteria. Plants also produce previously unidentified compounds that affect quorum sensing. We identified rosmarinic acid as a plant-derived compound that functioned as an HSL mimic. In vitro assays showed that rosmarinic acid bound to the quorum-sensing regulator RhlR of Pseudomonas aeruginosa PAO1 and competed with the bacterial ligand N-butanoyl-homoserine lactone (C4-HSL). Furthermore, rosmarinic acid stimulated a greater increase in RhlR-mediated transcription in vitro than that of C4-HSL. In P. aeruginosa, rosmarinic acid induced quorum sensing-dependent gene expression and increased biofilm formation and the production of the virulence factors pyocyanin and elastase. Because P. aeruginosa PAO1 infection induces rosmarinic acid secretion from plant roots, our results indicate that rosmarinic acid secretion is a plant defense mechanism to stimulate a premature quorum-sensing response. P. aeruginosa is a ubiquitous pathogen that infects plants and animals; therefore, identification of rosmarinic acid as an inducer of premature quorum-sensing responses may be useful in agriculture and inform human therapeutic strategies.

  8. Comparative Genomics of Acetobacterpasteurianus Ab3, an Acetic Acid Producing Strain Isolated from Chinese Traditional Rice Vinegar Meiguichu.

    Science.gov (United States)

    Xia, Kai; Li, Yudong; Sun, Jing; Liang, Xinle

    2016-01-01

    Acetobacter pasteurianus, an acetic acid resistant bacterium belonging to alpha-proteobacteria, has been widely used to produce vinegar in the food industry. To understand the mechanism of its high tolerance to acetic acid and robust ability of oxidizing ethanol to acetic acid (> 12%, w/v), we described the 3.1 Mb complete genome sequence (including 0.28 M plasmid sequence) with a G+C content of 52.4% of A. pasteurianus Ab3, which was isolated from the traditional Chinese rice vinegar (Meiguichu) fermentation process. Automatic annotation of the complete genome revealed 2,786 protein-coding genes and 73 RNA genes. The comparative genome analysis among A. pasteurianus strains revealed that A. pasteurianus Ab3 possesses many unique genes potentially involved in acetic acid resistance mechanisms. In particular, two-component systems or toxin-antitoxin systems may be the signal pathway and modulatory network in A. pasteurianus to cope with acid stress. In addition, the large numbers of unique transport systems may also be related to its acid resistance capacity and cell fitness. Our results provide new clues to understanding the underlying mechanisms of acetic acid resistance in Acetobacter species and guiding industrial strain breeding for vinegar fermentation processes.

  9. Microbial quality, physicochemical characteristics and fatty acid composition of a traditional butter produced from cows milk in East Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Idoui, T.; Benhamada, N.; Leghouchi, E.

    2010-07-01

    This is the first report describing microbiological, physicochemical properties and fatty acid composition of a traditional butter produced from cows milk in East of Algeria. Five butter samples were prepared in the laboratory according to the traditional method used by people in the Jijel areas (Eastern Algeria). Our results show the presence of lactic acid and psychrotrophic bacteria as well as yeasts, while staphylococci or lipolytic bacteria were not detected. Important differences were found in chemical values among butter samples. The pH values ranged from pH4.64 and pH5.53. Moisture and impurities exceeded 17.5% and 9.19% respectively. The values for acid index, peroxide index, saponification index and iodine index ranged from: 23.56-31.35mg KOH/g, 1.6-4 meq/kg, 140.25- 228.60 mg KOH/g and 35.35-53.69 mgI/100g respectively. Finally, the fatty acid composition showed that palmitic acid and oleic acid were the major saturated and unsaturated fatty acids. (Author) 20 refs.

  10. Bacillus spp. produce antibacterial activities against lactic acid bacteria that contaminate fuel ethanol plants

    Science.gov (United States)

    Lactic acid bacteria (LAB) frequently contaminate commercial fuel ethanol fermentations, reducing yields and decreasing profitability of biofuel production. Microorganisms from environmental sources in different geographic regions of Thailand were tested for antibacterial activity against LAB. Fou...

  11. Isolation, molecular characterization and screening of indigenous lactobacilli for their abilities to produce bioactive conjugated linoleic acid (CLA).

    Science.gov (United States)

    Dahiya, Dinesh Kumar; Puniya, Anil Kumar

    2017-03-01

    Ingestion of conjugated linoleic acid poised many health benefits; however, amount of CLA one can get through generalized diet in is inadequate in exerting the desired benefits. Therefore, presence of CLA producing lactobacilli in dairy fermented foods has a tremendous potential to increase the CLA content. Therefore, present study was focused to isolate and characterize CLA producing lactobacilli from different dairy products and human faeces. Arguably, 283 lactobacilli were isolated from various sources and tested for CLA production. Fifty-seven CLA producing (≥20 µg/ml) lactobacilli were selected from screening in de Man, Rogosa and Sharpe (MRS) broth and reconstituted with skim milk (SM), supplemented with 0.5 mg/ml of linoleic acid. Positive strains were classified into-L. plantarum (44%), L. gasseri (30%), L. fermentum (21%) and L. salivarius (5%) species. Nineteen most efficient strains (CLA ≥25 µg/ml) were further assessed in SM for CLA production. Total 08 strains produced significantly higher CLA in SM than MRS and also produced cis 9, trans 11, trans 10, cis 12 and trans 9, trans 11 isomers. Overall, L. plantarum HIF15 was reported as the best producer of CLA and other 08 lactobacilli may be utilized for the formulation of CLA-enriched functional foods to support these bacteria to synthesize CLA in the human gut.

  12. In vitro Characterization of Bacteriocin Produced by Lactic Acid Bacteria Isolated from Nem Chua, a Traditional Vietnamese Fermented Pork.

    Science.gov (United States)

    Pilasombut, Komkhae; Rumjuankiat, Kittaporn; Ngamyeesoon, Nualphan; Duy, Le Nguyen Doan

    2015-01-01

    The aim of this study was to screen and In vitro characterize the properties of bacteriocin produced by lactic acid bacteria isolated from Vietnamese fermented pork (Nem chua). One hundred and fifty LAB were isolated from ten samples of Nem chua and screened for bacteriocin-producing lactic acid bacteria. Antimicrobial activity of bacteriocin was carried out by spot on lawn method against both gram positive and gram negative bacteria. One isolate, assigned as KL-1, produced bacteriocin and showed inhibitory activity against Lactobacillus sakei, Leuconostoc mesenteroides and Enterococcus faecalis. To characterize the bacteriocin-producing strain, optimum temperature, incubation period for maximum bacteriocin production and identification of bacteriocin-producing strain were determined. It was found that the optimum cultivation temperature of the strain to produce the maximum bacteriocin activity (12,800 AU/mL) was obtained at 30℃. Meanwhile, bacteriocin production at 6,400 AU/mL was found when culturing the strain at 37℃ and 42℃. The isolate KL-1 was identified as L. plantarum. Antimicrobial activity of cell-free supernatant was completely inhibited by proteolytic enzyme of trypsin, alpha-chymotrypsin and proteinase K. Bacteriocin activity was stable at high temperature up to 100℃ for 10 min and at 4℃ storage for 2 d. However, the longer heating at 100℃ and 4℃ storage, its activity was reduced.

  13. Biological Control of Meloidogyne incognita by Aspergillus niger F22 Producing Oxalic Acid

    Science.gov (United States)

    Jang, Ja Yeong; Choi, Yong Ho; Shin, Teak Soo; Kim, Tae Hoon; Shin, Kee-Sun; Park, Hae Woong; Kim, Young Ho; Kim, Hun; Choi, Gyung Ja; Jang, Kyoung Soo; Cha, Byeongjin; Kim, In Seon; Myung, Eul Jae

    2016-01-01

    Restricted usage of chemical nematicides has led to development of environmentally safe alternatives. A culture filtrate of Aspergillus niger F22 was highly active against Meloidogyne incognita with marked mortality of second-stage juveniles (J2s) and inhibition of egg hatching. The nematicidal component was identified as oxalic acid by organic acid analysis and gas chromatography-mass spectroscopy (GC-MS). Exposure to 2 mmol/L oxalic acid resulted in 100% juvenile mortality at 1 day after treatment and suppressed egg hatching by 95.6% at 7 days after treatment. Oxalic acid showed similar nematicidal activity against M. hapla, but was not highly toxic to Bursaphelenchus xylophilus. The fungus was incubated on solid medium and dried culture was used for preparation of a wettable powder-type (WP) formulation as an active ingredient. Two WP formulations, F22-WP10 (ai 10%) and oxalic acid-WP8 (ai 8%), were prepared using F22 solid culture and oxalic acid. In a field naturally infested with M. incognita, application of a mixture of F22-WP10 + oxalic acid-WP8 at 1,000- and 500-fold dilutions significantly reduced gall formation on the roots of watermelon plants by 58.8 and 70.7%, respectively, compared to the non-treated control. The disease control efficacy of the mixture of F22-WP10 + oxalic acid-WP8 was significantly higher than that of a chemical nematicide, Sunchungtan (ai 30% fosthiazate). These results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease. PMID:27258452

  14. Biological Control of Meloidogyne incognita by Aspergillus niger F22 Producing Oxalic Acid.

    Directory of Open Access Journals (Sweden)

    Ja Yeong Jang

    Full Text Available Restricted usage of chemical nematicides has led to development of environmentally safe alternatives. A culture filtrate of Aspergillus niger F22 was highly active against Meloidogyne incognita with marked mortality of second-stage juveniles (J2s and inhibition of egg hatching. The nematicidal component was identified as oxalic acid by organic acid analysis and gas chromatography-mass spectroscopy (GC-MS. Exposure to 2 mmol/L oxalic acid resulted in 100% juvenile mortality at 1 day after treatment and suppressed egg hatching by 95.6% at 7 days after treatment. Oxalic acid showed similar nematicidal activity against M. hapla, but was not highly toxic to Bursaphelenchus xylophilus. The fungus was incubated on solid medium and dried culture was used for preparation of a wettable powder-type (WP formulation as an active ingredient. Two WP formulations, F22-WP10 (ai 10% and oxalic acid-WP8 (ai 8%, were prepared using F22 solid culture and oxalic acid. In a field naturally infested with M. incognita, application of a mixture of F22-WP10 + oxalic acid-WP8 at 1,000- and 500-fold dilutions significantly reduced gall formation on the roots of watermelon plants by 58.8 and 70.7%, respectively, compared to the non-treated control. The disease control efficacy of the mixture of F22-WP10 + oxalic acid-WP8 was significantly higher than that of a chemical nematicide, Sunchungtan (ai 30% fosthiazate. These results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease.

  15. 缺刻缘绿藻ω3脂肪酸去饱和酶基因(ω3FAD)在酿酒酵母中的低温诱导表达%Low-temperature-induced Expression of a ω3 Fatty Acid Desaturase Gene (ω3FAD)from Myrmecia incisa in Saccharomyces cerevisiae

    Institute of Scientific and Technical Information of China (English)

    李慧; 欧阳珑玲; 周志刚

    2012-01-01

    ω3脂肪酸去饱和酶(fatty acid desaturase,FAD)能使藻类细胞产生一系列具有高附加值的ω3脂肪酸.在已克隆到缺刻缘绿藻(Myrmecia incisa Reisigl)的ω3FAD基因基础上,为进一步了解其功能,本研究首先利用反转录PCR(RT-PCR)技术,克隆其开放阅读框(open reading frame,ORF)片段,然后亚克隆到穿梭表达载体pYES2中,以构建重组酵母表达载体pY-ω3FAD;通过电穿孔法将该重组载体转入酿酒酵母(Saccharomyces cerevisiae)INVSc1菌株中,经筛选与序列验证得到含有pY-ω3FAD重组质粒的酵母转化株.在5℃,添加底物亚麻酸及半乳糖诱导表达,连续培养72 h,经脂肪酸甲酯的气相色谱分析及气相色谱-质谱联用证明,转目的基因的酵母能将外源添加的亚油酸在15位脱氢生成α-亚麻酸,表明ω3FAD具有△15脂肪酸去饱和作用的功能.在不同温度条件下诱导培养时,气相色谱结果显示,在30℃培养的转基因酵母中没有检测到α-亚麻酸;但在不高于25℃培养的转基因酵母中,发现ω3FAD能将外源添加的底物去饱和为α-亚麻酸,且随着温度的降低,其去饱和能力增强,5℃时的底物转化效率达到29.73%.将转目的基因酵母在5℃温度下诱导培养不同时间,结果显示,随着培养时间的增加,LA(linoleic acid,亚油酸)转化为α-亚麻酸的效率也提高,培养4d时其转化效率达到38.86%.该研究结果提示,缺刻缘绿藻ω3FAD基因编码的酶蛋白为一个低温诱导酶.缺刻缘绿藻ω3FAD基因之所以能在酵母细胞中被低温诱导表达,可能因为后者存在一个低温诱导的脂肪酸去饱和系统.%Omega 3 fatty acid desaturase (FAD) enables algae to produce a series species of ω3 fatty acids of high-valued quality. Based on the sequence of a ω3FAD gene cloned from Myrmecia incisa Reisigl., its open reading frame (ORF) was amplified by RT-PCR and sub-cloned into the shuttle vector pYES2 to generate the recombinant vector

  16. Research on some factors influencing acid and exopolysaccharide produced by dairy propionibacterium strains isolated from traditional homemade Turkish cheeses.

    Science.gov (United States)

    Darilmaz, Derya Onal; Gumustekin, Yesim

    2012-05-01

    In this study, a total of 32 isolated strains and 5 reference strains of dairy propionibacteria were analyzed for acid and exopolysaccharide (EPS) production in skim milk and yeast extract-lactate broth (YEL) media in order to investigate the physiological background and preservative role of acid and EPS. The effects of final culture pH and optical density on acid and EPS production were also determined. On average, all strains produced more acid and reached lower final pH values in skim milk than in YEL medium. While the correlations obtained between the acid produced by propionibacterium strains and their final culture pH in skim milk medium were significant (P preservative in the food industry for replacement or reduction of the increasing use of chemical additives. The EPS production by propionibacterium strains during growth in YEL medium was 72 to 168 mg/liter, while in skim milk it was 94 to 359 mg/liter. The monomer compositions of the EPSs formed by the six selected dairy propionibacteria strains were analyzed. The EPSs may have applications as food grade additives and viscosity-stabilizing agents.

  17. Use of biodiesel-derived crude glycerol for producing eicosapentaenoic acid (EPA) by the fungus Pythium irregulare.

    Science.gov (United States)

    Athalye, Sneha K; Garcia, Rafael A; Wen, Zhiyou

    2009-04-01

    Crude glycerol is a major byproduct for the biodiesel industry. Producing value-added products through microbial fermentation on crude glycerol provides opportunities to utilize a large quantity of this byproduct. The objective of this study is to explore the potential of using crude glycerol for producing eicosapentaenoic acid (EPA, 20:5 n-3) by the fungus Pythium irregulare . When P. irregulare was grown in medium containing 30 g/L crude glycerol and 10 g/L yeast extract, EPA yield and productivity reached 90 mg/L and 14.9 mg/L x day, respectively. Adding pure vegetable oils (flaxseed oil and soybean oil) to the culture greatly enhanced the biomass and the EPA production. This enhancement was due to the oil absorption by the fungal cells and elongation of shorter chain fatty acids (e.g., linoleic acid and alpha-linolenic acid) into longer chain fatty acid (e.g., EPA). The major impurities contained in crude glycerol, soap and methanol, were inhibitory to fungal growth. Soap can be precipitated from the liquid medium through pH adjustment, whereas methanol can be evaporated from the medium during autoclaving. The glycerol-derived fungal biomass contained about 15% lipid, 36% protein, and 40% carbohydrate, with 9% ash. In addition to EPA, the fungal biomass was also rich in the essential amino acids lysine, arginine, and leucine, relative to many common feedstuffs. Elemental analysis by inductively coupled plasma showed that aluminum, calcium, copper, iron, magnesium, manganese, phosphorus, potassium, silicon, sodium, sulfur, and zinc were present in the biomass, whereas no heavy metals (such as mercury and lead) were detected. The results show that it is feasible to use crude glycerol for producing fungal biomass that can serve as EPA-fortified food or feed.

  18. Ethanol production from acid- and alkali-pretreated corncob by endoglucanase and β-glucosidase co-expressing Saccharomyces cerevisiae subject to the expression of heterologous genes and nutrition added.

    Science.gov (United States)

    Feng, Chunying; Zou, Shaolan; Liu, Cheng; Yang, Huajun; Zhang, Kun; Ma, Yuanyuan; Hong, Jiefang; Zhang, Minhua

    2016-05-01

    Low-cost technologies to overcome the recalcitrance of cellulose are the key to widespread utilization of lignocellulosic biomass for ethanol production. Efficient enzymatic hydrolysis of cellulose requires the synergism of various cellulases, and the ratios of each cellulase are required to be regulated to achieve the maximum hydrolysis. On the other hand, engineering of cellulolytic Saccharomyces cerevisiae strains is a promising strategy for lignocellulosic ethanol production. The expression of cellulase-encoding genes in yeast would affect the synergism of cellulases and thus the fermentation ability of strains with exogenous enzyme addition. However, such researches are rarely reported. In this study, ten endoglucanase and β-glucosidase co-expressing S. cerevisiae strains were constructed and evaluated by enzyme assay and fermentation performance measurement. The results showed that: (1) maximum ethanol titers of recombinant strains exhibited high variability in YPSC medium (20 g/l peptone, 10 g/l yeast extract, 100 g/l acid- and alkali-pretreated corncob) within 10 days. However, they had relatively little difference in USC medium (100 g/l acid- and alkali-pretreated corncob, 0.33 g/l urea, pH 5.0). (2) Strains 17# and 19#, with ratio (CMCase to β-glucosidase) of 7.04 ± 0.61 and 7.40 ± 0.71 respectively, had the highest fermentation performance in YPSC. However, strains 11# and 3# with the highest titers in USC medium had a higher ratio of CMCase to β-glucosidase, and CMCase activities. These results indicated that nutrition, enzyme activities and the ratio of heterologous enzymes had notable influence on the fermentation ability of cellulase-expressing yeast.

  19. Recycling of carbon dioxide and acetate as lactic acid by the hydrogen-producing bacterium Thermotoga neapolitana.

    Science.gov (United States)

    d'Ippolito, Giuliana; Dipasquale, Laura; Fontana, Angelo

    2014-09-01

    The heterotrophic bacterium Thermotoga neapolitana produces hydrogen by fermentation of sugars. Under capnophilic (carbon dioxide requiring) conditions, the process is preferentially associated with the production of lactic acid, which, as shown herein, is synthesized by reductive carboxylation of acetyl coenzyme A. The enzymatic coupling is dependent on the carbon dioxide stimulated activity of heterotetrameric pyruvate:ferredoxin oxidoreductase. Under the same culture conditions, T. neapolitana also operates the unfavorable synthesis of lactic acid from an exogenous acetate supply. This process, which requires carbon dioxide (or carbonate) and an unknown electron donor, allows for the conversion of carbon dioxide into added-value chemicals without biomass deconstruction.

  20. Gelation properties of spent duck meat surimi-like material produced using acid-alkaline solubilization methods.

    Science.gov (United States)

    Nurkhoeriyati, T; Huda, N; Ahmad, R

    2011-01-01

    The gelation properties of spent duck meat surimi-like material produced using acid solubilization (ACS) or alkaline solubilization (ALS) were studied and compared with conventionally processed (CON) surimi-like material. The ACS process yielded the highest protein recovery (P process generated the highest lipid reduction, and the CON process yielded the lowest reduction (P process had the highest gel strength, salt extractable protein (SEP), and water holding capacity (WHC), followed by materials produced via the ALS and ACS processes and untreated duck meat (P process also had the highest cohesiveness, hardness, and gumminess values and the lowest springiness value. Material produced by the ACS and ALS processes had higher whiteness values than untreated duck meat gels and gels produced by the CON method (P processes had significantly higher myoglobin removal (P gelation and color properties of spent duck and possibly applied for other high fat raw material.

  1. Application of hydrothermally produced TiO{sub 2} nanotubes in photocatalytic esterification of oleic acid

    Energy Technology Data Exchange (ETDEWEB)

    Manique, Márcia Cardoso, E-mail: marciamanique@yahoo.com.br; Silva, Aline Posteral; Alves, Annelise Kopp; Bergmann, Carlos Pérez

    2016-04-15

    Highlights: • A hydrothermal method was employed to synthesize TiO{sub 2} nanotubes. • TiO{sub 2} nanotubes were studied for photocatalytic esterification of oleic acid. • Optimum conditions were obtained at a concentration of 15% (w/w) and a molar ratio 3:1 (methanol:oleic acid). • The greater number of hydroxyl groups may have contributed to a low yield of ester versus P25. - Abstract: This study investigated the use of TiO{sub 2} nanotubes (TNTs) as photocatalysts in the esterification of fatty acids for biodiesel production. The TNTs were synthesized via a hydrothermal route and evaluated for their crystallinity, morphology, surface area and photocatalytic activity compared with a TiO{sub 2} P25 standard. Optimum photocatalytic conditions were obtained using a 15% concentration of catalyst (w/w) and a 3:1 molar ratio of methanol to oleic acid. The highest yield of methyl oleate obtained was 86.0% when P25 was used as a photocatalyst. The lowest band gap energy was obtained with the TNT sample synthesized at 110 °C for 48 h (E{sub g} = 3.08 eV), which also exhibited the highest rate of oleic acid esterification (59.3%) among all the investigated TNTs. We also observed that, in addition to the band gap, other factors such as the crystalline phase of the TNTs and their surface area were important in photocatalytic performance.

  2. The Antibacterial Activity of Acetic Acid against Biofilm-Producing Pathogens of Relevance to Burns Patients.

    Directory of Open Access Journals (Sweden)

    Fenella D Halstead

    Full Text Available Localised infections, and burn wound sepsis are key concerns in the treatment of burns patients, and prevention of colonisation largely relies on biocides. Acetic acid has been shown to have good antibacterial activity against various planktonic organisms, however data is limited on efficacy, and few studies have been performed on biofilms.We sought to investigate the antibacterial activity of acetic acid against important burn wound colonising organisms growing planktonically and as biofilms.Laboratory experiments were performed to test the ability of acetic acid to inhibit growth of pathogens, inhibit the formation of biofilms, and eradicate pre-formed biofilms.Twenty-nine isolates of common wound-infecting pathogens were tested. Acetic acid was antibacterial against planktonic growth, with an minimum inhibitory concentration of 0.16-0.31% for all isolates, and was also able to prevent formation of biofilms (at 0.31%. Eradication of mature biofilms was observed for all isolates after three hours of exposure.This study provides evidence that acetic acid can inhibit growth of key burn wound pathogens when used at very dilute concentrations. Owing to current concerns of the reducing efficacy of systemic antibiotics, this novel biocide application offers great promise as a cheap and effective measure to treat infections in burns patients.

  3. A microbial transformation using Bacillus subtilis B7-S to produce natural vanillin from ferulic acid.

    Science.gov (United States)

    Chen, Peng; Yan, Lei; Wu, Zhengrong; Li, Suyue; Bai, Zhongtian; Yan, Xiaojuan; Wang, Ningbo; Liang, Ning; Li, Hongyu

    2016-02-04

    Bacillus subtilis strain B7-S screened from18 strains is an aerobic, endospore-forming, model organism of Gram-positive bacteria which is capable to form vanillin during ferulic acid bioconversion. The bioconversion of ferulic acid to vanillin by Bacillus subtilis B7-S (B. subtilis B7-S) was investigated. Based on our results, the optimum bioconversion conditions for the production of vanillin by B. subtilis B7-S can be summarized as follows: temperature 35 °C; initial pH 9.0; inoculum volume 5%; ferulic acid concentration 0.6 g/L; volume of culture medium 20%; and shaking speed 200 r/min. Under these conditions, several repeated small-scale batch experiments showed that the maximum conversion efficiency was 63.30% after 3 h of bioconversion. The vanillin products were confirmed by spectral data achieved from UV-vis, inductively coupled plasma atomic emission spectroscope (ICP-AES) and Fourier transform infrared spectrometer (FT-IR) spectra. Scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM) results confirmed that the cell surface of B. subtilis plays a role in the induction of ferulic acid tolerance. These results demonstrate that B. subtilis B7-S has the potential for use in vanillin production through bioconversion of ferulic acid.

  4. p-Aminoacetophenonic Acids Produced by a Mangrove Endophyte Streptomyces sp. (strain HK10552

    Directory of Open Access Journals (Sweden)

    Fangfang Wang

    2010-04-01

    Full Text Available Four new p-aminoacetophenonic acids, named (2E-11-(4′-aminophenyl-5,9-dihydroxy-4,6,8-trimethyl-11-oxo-undec-2-enoic acid (1, 9-(4′-aminophenyl-3,7-dihydroxy-2,4,6-trimethyl-9-oxo-nonoic acid(2, (2E-11-(4′-aminophenyl-5,9-O-cyclo-4,6,8-trimethyl-11-oxo-undec-2-enoic acid (3 and 9-(4′-aminophenyl-3,7-O-cyclo-2,4,6-trimethyl-9-oxo-nonoic acid(4, were isolated from an endophyte Streptomyces sp. (strain HK10552 of the mangrove plant Aegiceras corniculatum. The structures of 1–4 were elucidated by using spectroscopic analyses. The relative stereoconfigurations of compounds 3 and 4 were determined by NOESY experiments. In the bioassay test, 1–4 showed no cytotoxicity against the Hela cell lines. Compound 4 also showed no inhibitory bioactivity on HCV protease and SecA ATPase and wasn’t active against VSVG/HIV-luc pseudotyping virus.

  5. Genomewide expression analysis in amino acid-producing bacteria using DNA microarrays.

    Science.gov (United States)

    Polen, Tino; Wendisch, Volker F

    2004-01-01

    DNA microarray technology has become an important research tool for biotechnology and microbiology. It is now possible to characterize genetic diversity and gene expression in a genomewide manner. DNA microarrays have been applied extensively to study the biology of many bacteria including Escherichia coli, but only recently have they been developed for the Gram-positive Corynebacterium glutamicum. Both bacteria are widely used for biotechnological amino acid production. In this article, in addition to the design and generation of microarrays as well as their use in hybridization experiments and subsequent data analysis, we describe recent applications of DNA microarray technology regarding amino acid production in C. glutamicum and E. coli. We also discuss the impact of functional genomics studies on fundamental as well as applied aspects of amino acid production with C. glutamicum and E. coli.

  6. Imaging Cancer Cells Expressing the Folate Receptor with Carbon Dots Produced from Folic Acid.

    Science.gov (United States)

    Bhunia, Susanta Kumar; Maity, Amit Ranjan; Nandi, Sukhendu; Stepensky, David; Jelinek, Raz

    2016-04-01

    Development of new imaging tools for cancer cells in vitro and in vitro is important for advancing cancer research, elucidating drug effects upon cancer cells, and studying cellular processes. We showed that fluorescent carbon dots (C-dots) synthesized from folic acid can serve as an effective vehicle for imaging cancer cells expressing the folate receptor on their surface. The C-dots, synthesized through a simple one-step process from folic acid as the carbon source, exhibited selectivity towards cancer cells displaying the folate receptor, making such cells easily distinguishable in fluorescence microscopy imaging. Biophysical measurements and competition experiments both confirmed the specific targeting and enhanced uptake of C-dots by the folate receptor-expressing cells. The folic acid-derived C-dots were not cytotoxic, and their use in bioimaging applications could aid biological studies of cancer cells, identification of agonists/antagonists, and cancer diagnostics.

  7. Biotechnological potential of a rhizosphere Pseudomonas aeruginosa strain producing phenazine-1-carboxylic acid and phenazine-1-carboxamide.

    Science.gov (United States)

    Zhou, Lian; Jiang, Hai-Xia; Sun, Shuang; Yang, Dan-Dan; Jin, Kai-Ming; Zhang, Wei; He, Ya-Wen

    2016-03-01

    Bacterial phenazine metabolites belong to a group of nitrogen-containing heterocyclic compounds with antimicrobial activities. In this study, a rhizosphere Pseudomonas aeruginosa strain PA1201 was isolated and identified through 16S rDNA sequence analysis and fatty acid profiling. PA1201 inhibited the growth of various pathogenic microorganisms, including Rhizotonia solani, Magnaporthe grisea, Fusarium graminearum, Xanthomonas oryzae pv. oryzae, Xanthomonas oryzae pv. oryzicola, and Staphylococcus aureus. High Performance Liquid Chromatography showed that PA1201 produced high levels of phenazine-1-carboxylic acid (PCA), a registered green fungicide 'Shenqinmycin' with the fermentation titers of 81.7 mg/L in pigment producing medium (PPM) and 926.9 mg/L in SCG medium containing soybean meal, corn steep liquor and glucose. In addition, PA1201 produced another antifungal metabolite, phenazine-1-carboxaminde (PCN), a derivative of PCA, with the fermentation titers of 18.1 and 489.5 mg/L in PPM and SCG medium respectively. To the best of our knowledge, PA1201 is a rhizosphere originating P. aeruginosa strain that congenitally produces the highest levels of PCA and PCN among currently reported P. aeruginosa isolates, which endows it great biotechnological potential to be transformed to a biopesticide-producing engineering strain.

  8. Design of aqueous two-phase systems for purification of hyaluronic acid produced by metabolically engineered Lactococcus lactis.

    Science.gov (United States)

    Rajendran, Vivek; Puvendran, Kirubhakaran; Guru, Bharath Raja; Jayaraman, Guhan

    2016-02-01

    Hyaluronic acid has a wide range of biomedical applications and its commercial value is highly dependent on its purity and molecular weight. This study highlights the utility of aqueous two-phase separation as a primary recovery step for hyaluronic acid and for removal of major protein impurities from fermentation broths. Metabolically engineered cultures of a lactate dehydrogenase mutant strain of Lactococcus lactis (L. lactis NZ9020) were used to produce high-molecular-weight hyaluronic acid. The cell-free fermentation broth was partially purified using a polyethylene glycol/potassium phosphate system, resulting in nearly 100% recovery of hyaluronic acid in the salt-rich bottom phase in all the aqueous two-phase separation experiments. These experiments were optimized for maximum removal of protein impurities in the polyethylene glycol rich top phase. The removal of protein impurities resulted in substantial reduction of membrane fouling in the subsequent diafiltration process, carried out with a 300 kDa polyether sulfone membrane. This step resulted in considerable purification of hyaluronic acid, without any loss in recovery and molecular weight. Diafiltration was followed by an adsorption step to remove minor impurities and achieve nearly 100% purity. The final hyaluronic acid product was characterized by Fourier-transform IR and NMR spectroscopy, confirming its purity.

  9. Bacteriocin-Producing Lactic Acid Bacteria Isolated from Traditional Fermented Food

    Science.gov (United States)

    Kormin, Salasiah; Rusul, Gulam; Radu, Son; Ling, Foo Hooi

    2001-01-01

    Lactic Acid Bacteria (LAB) isolated from several traditional fermented foods such as “tempeh”, “tempoyak” and “tapai” were screened for the production of bacteriocin. One strain isolated from “tempeh” gives an inhibitory activity against several LAB. The strain was later identified as Lactobacillus plantarum BS2. Study shows that the inhibitory activity was not caused by hydrogen peroxide, organic acids or bacteriophage. The bacteriocin production was maximum after 10 hours of incubation with an activity of 200 AU/ml. The bacteriocin was found to be sensitive towards trypsin, α-chymotrypsin, β-chymotrypsin, α-amylase and lysozyme. PMID:22973159

  10. Gene characterized for membrane desaturase that produces (E)-11 isomers of mono- and diunsaturated fatty acids

    OpenAIRE

    Liu, Weitian; Jiao, Hongmei; Murray, Nancy C.; O'Connor, Marion; Roelofs, Wendell L.

    2002-01-01

    Moth species have evolved integral membrane desaturases that exhibit a wide diversity in substrate specificity, as well as in regiospecificity and stereospecificity of the unsaturated products. We report here the cloning and expression of a single desaturase from the sex pheromone gland of the light brown apple moth, Epiphyas postvittana, that makes E11 isomers of monounsaturated (E11-16 and E11-14) fatty acids and a diunsaturated (E9,E11-14) fatty acid. In the pheromone gland, the monoene pr...

  11. Methods of refining and producing dibasic esters and acids from natural oil feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Snead, Thomas E.; Cohen, Steven A.; Gildon, Demond L.

    2016-06-14

    Methods and systems for making dibasic esters and/or dibasic acids using metathesis are generally disclosed. In some embodiments, the methods comprise reacting a terminal olefin ester with an internal olefin ester in the presence of a metathesis catalyst to form a dibasic ester and/or dibasic acid. In some embodiments, the terminal olefin ester or the internal olefin ester are derived from a renewable feedstock, such as a natural oil feedstock. In some such embodiments, the natural oil feedstock, or a transesterified derivative thereof, is metathesized to make the terminal olefin ester or the internal olefin ester.

  12. Susceptibility of Saccharomyces cerevisiae and lactic acid bacteria from the alcohol industry to several antimicrobial compounds Susceptibilidade de Saccharomyces cerevisiae e bactérias láticas provenientes de indústrias alcooleiras a vários compostos antimicrobianos

    Directory of Open Access Journals (Sweden)

    Pedro de Oliva-Neto

    2001-03-01

    Full Text Available The antimicrobial effect of several products including commercial formulations currently used in sugar and alcohol factories was determined by adapted MIC (Minimal Inhibitory Concentration test on Saccharomyces cerevisiae and on natural contaminants Lactobacillus fermentum and Leuconostoc mesenteroides. The MIC test by macrodilution broth method was adapted by formulating of the culture medium with cane juice closely simulating industrial alcoholic fermentation must. Acid penicillin V (MIC 0.10-0.20 µg/ml and clindamycin (MIC 0.05-0.40 µg/ml were most effective against bacterial growth in 24 h. Among the chemicals, sulphite (MIC 10-40 µg/ml, nitrite (MIC 50 µg/ml. Methyldithiocarbamate was efficient only on L. fermentum (MIC 2.5 µg/ml and S. cerevisiae (MIC 5.0 µg/ml. Thiocianate (MIC 1.2-5.0 µg/ml, bromophenate (MIC 9-18 µg/ml and n- alkyldimethylbenzylammonium cloride (MIC 1-8 µg/ml affected S. cerevisiae at similar inhibitory concentration for L. mesenteroides or L. fermentum. Formaldehyde was more effective on bacteria (MIC 11.5 - 23 µg/ml in both pH (4.5 and 6.5 than yeast (MIC 46-92 µg/ml. Several tested formulated biocides seriously affect S. cerevisiae growth in the similar dosages of the bacterial inhibition, so these products should be avoided or used only in special conditions for the bacterium control of fermentation process. For this step, the control of these contaminants by antibiotics are more suitable and effective.O efeito antimicrobiano de vários produtos incluindo formulações comerciais usualmente utilizadas em usinas de açúcar e álcool foi determinado pelo teste da Concentração Mínima Inibitória (CMI adaptada para Saccharomyces cerevisiae e os contaminantes naturais Lactobacillus fermentum and Leuconostoc mesenteroides. O teste da CMI foi feito pela adaptação do método da Macrodiluição em caldo pela formulação de um meio de cultivo com caldo de cana em condições similares ao mosto da fermenta

  13. Purification and characterization of hyaluronic acid produced by Streptococcus zooepidemicus strain 3523-7

    Directory of Open Access Journals (Sweden)

    K. Jagadeeswara Reddy

    2013-01-01

    Full Text Available Hyaluronic acid (HA is a hydrated gel and comprises repeating units of glucuronic acid and N-acetylglucosamine. Production and recovery of HA has gained great importance due to its vast clinical applications. In pursuit of obtaining highly pure HA, we have developed a fed-batch fermentation process using Streptococcus zooepidemicus in a 25 L bioreactor that resulted in a maximum yield of 2.3 g/L HA. In addition, we have devised an efficient method for separation and recovery of hyaluronic acid from a highly viscous broth by treating with trichloroacetic acid (0.1% and charcoal (1-2%, passing through filtration (0.45 μm and ultrafiltration that resulted in recovery of 72.2% of clinical grade HA with molecular weight of 2.5×106 Da. We have also characterized our purified HA using FTIR and NMR spectroscopy. These studies revealed the similarity in both the FTIR spectrum as well as NMR spectrum of both reference standard and purified HA from S. zooepidemicus indicating that the reported process is more efficient in terms of better yield and high quality (99.2%.

  14. Antimicrobial resistance of coagulase-negative staphylococci and lactic acid bacteria from industrially produced dairy products

    Directory of Open Access Journals (Sweden)

    Nevijo Zdolec

    2013-03-01

    Full Text Available In this research, the susceptibility to clindamycin, tetracycline, amikacin, amoxicillin + clavulanic acid, enrofloxacine, vancomycin, trimethoprim + sulphametoxazol, tobramycin, chloramphenicol, ciprofloxacin, erythromycin, penicillin and trimethoprim was tested in coagulase-negative staphylococci (n=78 and lactic acid bacteria (n=30 by means of disk diffusion test and E-test. The isolates were collected from soft and hard cheeses, butter and brine. All isolates of coagulase-negative staphylococci were susceptible to clindamycin, amikacin, amoxicillin + clavulanic acid, enrofloxacine, vancomycin, chloramphenicol and ciprofloxacin according to CLSI breakpoints. A total of 30 staphylococci isolates (38.46 % were resistant to erythromycin, 18 to penicillin (23.07 %, 4 to tetracycline (5.12 %, and one isolate to trimethoprim, tobramicin and trimethoprim + sulphametoxazol (1.28 %. Among 78 tested staphylococci, 35 of them were resistant to at least one antimicrobial substance (44.87 %. The rate of resistant isolates of different soft cheese types ranged from 22 to 70 %, while resistant staphylococci were absent in hard cheese and brine. The growth of lactic acid bacteria was not influenced by trimethoprim + sulphametoxazol (n=29, vancomycin (n=29, trimethoprim (n=28, amikacin (n=10 and tobramycin (n=10. The results show that significant part of apathogenic microbiota in different dairy products is phenotypically resistant to antimicrobial agents.

  15. Umami taste amino acids produced by hydrolyzing extracted protein from tomato seed meal

    Science.gov (United States)

    Enzymatic hydrolysis was performed for extracting protein to prepare umami taste amino acids from defatted tomato seed meal (DTSM) which is a by-product of tomato processing. Papain was used as an enzyme for the hydrolysis of DTSM. The particle size distribution of DTSM, protein concentration and fr...

  16. Comparative studies of various hyaluronic acids produced by microbial fermentation for potential topical ophthalmic applications

    DEFF Research Database (Denmark)

    Guillaumie, Fanny; Furrer, Pascal; Felt-Baeyens, Olivia;

    2010-01-01

    capacity, sterile filtration, rheological properties, precorneal residence time and ocular tolerance of ophthalmic solutions was investigated. Molecular weight did not affect hydration of hyaluronic acid according to differential scanning calorimetry (DSC). In general, medium MW HA (0.6–1 MDa) resulted...

  17. Endophytic fungi produce gibberellins and indoleacetic acid and promotes host-plant growth during stress.

    Science.gov (United States)

    Waqas, Muhammad; Khan, Abdul Latif; Kamran, Muhammad; Hamayun, Muhammad; Kang, Sang-Mo; Kim, Yoon-Ha; Lee, In-Jung

    2012-09-07

    We isolated and examined two endophytic fungi for their potential to secrete phytohormones viz. gibberellins (GAs) and indoleacetic acid (IAA) and mitigate abiotic stresses like salinity and drought. The endophytic fungi Phoma glomerata LWL2 and Penicillium sp. LWL3 significantly promoted the shoot and allied growth attributes of GAs-deficient dwarf mutant Waito-C and Dongjin-beyo rice. Analysis of the pure cultures of these endophytic fungi showed biologically active GAs (GA1, GA3, GA4 and GA7) in various quantities. The cultures of P. glomerata and Penicillium sp. also contained IAA. The culture application and endophytic-association with host-cucumber plants significantly increased the plant biomass and related growth parameters under sodium chloride and polyethylene glycol induced salinity and drought stress as compared to control plants. The endophytic symbiosis resulted in significantly higher assimilation of essential nutrients like potassium, calcium and magnesium as compared to control plants during salinity stress. Endophytic-association reduced the sodium toxicity and promoted the host-benefit ratio in cucumber plants as compared to non-inoculated control plants. The symbiotic-association mitigated stress by compromising the activities of reduced glutathione, catalase, peroxidase and polyphenol oxidase. Under stress conditions, the endophyte-infection significantly modulated stress through down-regulated abscisic acid, altered jasmonic acid, and elevated salicylic acid contents as compared to control. In conclusion, the two endophytes significantly reprogrammed the growth of host plants during stress conditions.

  18. Endophytic Fungi Produce Gibberellins and Indoleacetic Acid and Promotes Host-Plant Growth during Stress

    Directory of Open Access Journals (Sweden)

    In-Jung Lee

    2012-09-01

    Full Text Available We isolated and examined two endophytic fungi for their potential to secrete phytohormones viz. gibberellins (GAs and indoleacetic acid (IAA and mitigate abiotic stresses like salinity and drought. The endophytic fungi Phoma glomerata LWL2 and Penicillium sp. LWL3 significantly promoted the shoot and allied growth attributes of GAs-deficient dwarf mutant Waito-C and Dongjin-beyo rice. Analysis of the pure cultures of these endophytic fungi showed biologically active GAs (GA1, GA3, GA4 and GA7 in various quantities. The cultures of P. glomerata and Penicillium sp. also contained IAA. The culture application and endophytic-association with host-cucumber plants significantly increased the plant biomass and related growth parameters under sodium chloride and polyethylene glycol induced salinity and drought stress as compared to control plants. The endophytic symbiosis resulted in significantly higher assimilation of essential nutrients like potassium, calcium and magnesium as compared to control plants during salinity stress. Endophytic-association reduced the sodium toxicity and promoted the host-benefit ratio in cucumber plants as compared to non-inoculated control plants. The symbiotic-association mitigated stress by compromising the activities of reduced glutathione, catalase, peroxidase and polyphenol oxidase. Under stress conditions, the endophyte-infection significantly modulated stress through down-regulated abscisic acid, altered jasmonic acid, and elevated salicylic acid contents as compared to control. In conclusion, the two endophytes significantly reprogrammed the growth of host plants during stress conditions.

  19. Influence of the nitrogen source on Saccharomyces cerevisiae anaerobic growth and product formation.

    Science.gov (United States)

    Albers, E; Larsson, C; Lidén, G; Niklasson, C; Gustafsson, L

    1996-09-01

    To prevent the loss of raw material in ethanol production by anaerobic yeast cultures, glycerol formation has to be reduced. In theory, this may be done by providing the yeast with amino acids, since the de novo cell synthesis of amino acids from glucose and ammonia gives rise to a surplus of NADH, which has to be reoxidized by the formation of glycerol. An industrial strain of Saccharomyces cerevisiae was cultivated in batch cultures with different nitrogen sources, i.e., ammonium salt, glutamic acid, and a mixture of amino acids, with 20 g of glucose per liter as the carbon and energy source. The effects of the nitrogen source on metabolite formation, growth, and cell composition were measured. The glycerol yields obtained with glutamic acid (0.17 mol/mol of glucose) or with the mixture of amino acids (0.10 mol/mol) as a nitrogen source were clearly lower than those for ammonium-grown cultures (0.21 mol/mol). In addition, the ethanol yield increased for growth on both glutamic acid (by 9%) and the mixture of amino acids (by 14%). Glutamic acid has a large influence on the formation of products; the production of, for example, alpha-ketoglutaric acid, succinic acid, and acetic acid, increased compared with their production with the other nitrogen sources. Cultures grown on amino acids have a higher specific growth rate (0.52 h-1) than cultures of both ammonium-grown (0.45 h-1) and glutamic acid-grown (0.33 h-1) cells. Although the product yields differed, similar compositions of the cells were attained. The NADH produced in the amino acid, RNA, and extracellular metabolite syntheses was calculated together with the corresponding glycerol formation. The lower-range values of the theoretically calculated yields of glycerol were in good agreement with the experimental yields, which may indicate that the regulation of metabolism succeeds in the most efficient balancing of the redox potential.

  20. Consumer protection through a legislative ban on industrially produced trans fatty acids in foods in Denmark

    DEFF Research Database (Denmark)

    Stender, Steen; Dyerberg, Jørn; Astrup, Arne

    2006-01-01

    Legislation has, within a few years, virtually eliminated the intake of industrially produced trans fatty acids (IP-TFA) in Denmark, by banning any food with an IP-TFA content greater than 2% of total fat. This accomplishment has been obtained without noticeable effects on the availability, price...... their risk of coronary heart disease. The Danish experience demonstrates that this risk can be eliminated...

  1. Gluconacetobacter maltaceti sp. nov., a novel vinegar producing acetic acid bacterium.

    Science.gov (United States)

    Slapšak, Nina; Cleenwerck, Ilse; De Vos, Paul; Trček, Janja

    2013-02-01

    Comparison of HaeIII- and HpaII-restriction profiles of PCR-amplified 16S-23S rDNA ITS regions of Gluconacetobacter sp. LMG 1529(T) and SKU 1109 with restriction profiles of reference strains of acetic acid bacteria described by Trček and Teuber [34] revealed the same but unique restriction profiles for LMG 1529(T) and SKU 1109. Further analyses of nearly complete 16S rRNA gene sequences, nearly complete 16S-23S rDNA ITS sequences, as well as concatenated partial sequences of the housekeeping genes dnaK, groEL and rpoB, allocated both strains to a single phylogenetic cluster well separated from the other species of the genus Gluconacetobacter. DNA-DNA hybridizations confirmed their novel species identity by 73% DNA-DNA relatedness between both strains, and values below the species level (<70%) between SKU 1109 and the type strains of the closest phylogenetic neighbors. The classification of strains LMG 1529(T) and SKU 1109 into a single novel species was confirmed also by AFLP and (GTG)(5)-PCR DNA fingerprinting data, as well as by phenotypic data. Strains LMG 1529(T) and SKU 1109 can be differentiated from their closely related Gluconacetobacter species, Gluconacetobacter entanii and Gluconacetobacter hansenii, by their ability to form 2-keto-d-gluconic acid from d-glucose, their ability to use d-mannitol, d-gluconate and glycerol as carbon source and form acid from d-fructose, and their ability to grow without acetic acid. The major fatty acid of LMG 1529(T) and SKU 1109 is C(18:1ω7c) (60.2-64.8%). The DNA G+C content of LMG 1529(T) and SKU 1109 is 62.5 and 63.3mol% respectively. The name Gluconacetobacter maltaceti sp. nov. is proposed. The type strain is LMG 1529(T) (=NBRC 14815(T)=NCIMB 8752(T)).

  2. Lipase-catalyzed process in an anhydrous medium with enzyme reutilization to produce biodiesel with low acid value.

    Science.gov (United States)

    Azócar, Laura; Ciudad, Gustavo; Heipieper, Hermann J; Muñoz, Robinson; Navia, Rodrigo

    2011-12-01

    One major problem in the lipase-catalyzed production of biodiesel or fatty acid methyl esters (FAME) is the high acidity of the product, mainly caused by water presence, which produces parallel hydrolysis and esterification reactions instead of transesterification to FAME. Therefore, the use of reaction medium in absence of water (anhydrous medium) was investigated in a lipase-catalyzed process to improve FAME yield and final product quality. FAME production catalyzed by Novozym 435 was carried out using waste frying oil (WFO) as raw material, methanol as acyl acceptor, and 3Å molecular sieves to extract the water. The anhydrous conditions allowed the esterification of free fatty acids (FFA) from feedstock at the initial reaction time. However, after the initial esterification process, water absence avoided the consecutives reactions of hydrolysis and esterification, producing FAME mainly by transesterification. Using this anhydrous medium, a decreasing in both the acid value and the diglycerides content in the product were observed, simultaneously improving FAME yield. Enzyme reuse in the anhydrous medium was also studied. The use of the moderate polar solvent tert-butanol as a co-solvent led to a stable catalysis using Novozym 435 even after 17 successive cycles of FAME production under anhydrous conditions. These results indicate that a lipase-catalyzed process in an anhydrous medium coupled with enzyme reuse would be suitable for biodiesel production, promoting the use of oils of different origin as raw materials.

  3. Production of conjugated linoleic acid (CLA) by Bifidobacterium breve LMC520 and its compatibility with CLA-producing rumen bacteria.

    Science.gov (United States)

    Park, Hui Gyu; Heo, Wan; Kim, Sang Bum; Kim, Hyun Seop; Bae, Gui Seck; Chung, Soo Hyun; Seo, Ho-Chan; Kim, Young Jun

    2011-02-09

    This study was performed to characterize the ability of an active Bifidobacterium strain to produce conjugated linoleic acid (CLA) and to test its possible utilization as a probiotic compatible to the ruminal condition. Bifidobacterium breve LMC520 can actively convert linoleic acid (LA) to cis-9,trans-11-CLA, which is a major isomer derived from microbial conversion. LMC520 showed reasonable tolerance under acidic conditions (pH 2.5 with 1% pepsin) and in the presence of oxgall (0-3%). The growth and CLA production of LMC520 were tested under ruminal conditions and compared with those of Butyrivibrio fibrisolvens A38, which is a major CLA producer in the rumen as an intermediate in the biohydrogenation (BH) process. LMC520 converted 15% of LA to CLA under ruminal conditions, which was 2 times higher activity than that of A38, and there was no decline in CLA level during prolonged incubation of 48 h. The BH activity of LMC520 was comparable to that of A38. When LMC520 was cocultured with A38, even with slight decrease of CLA due to high BH activity by A38, but the level of CLA was maintained by the high CLA-producing activity of LMC520. This comparative study shows the potential of this strain to be applied as a functional probiotic not only for humans but also for ruminants as well as to increase CLA production.

  4. Photocatalytic decomposition of humic acids in anoxic aqueous solutions producing hydrogen, oxygen and light hydrocarbons.

    Science.gov (United States)

    Klauson, Deniss; Budarnaja, Olga; Beltran, Ignacio Castellanos; Krichevskaya, Marina; Preis, Sergei

    2014-01-01

    Photocatalytic water splitting for hydrogen and oxygen production requires sacrificial electron donors, for example, organic compounds. Titanium dioxide catalysts doped with platinum, cobalt, tungsten, copper and iron were experimentally tested for the production of hydrogen, oxygen and low molecular weight hydrocarbons from aqueous solutions of humic substances (HS). Platinum-doped catalyst showed the best results in hydrogen generation, also producing methane, ethene and ethane, whereas the best oxygen production was exhibited by P25, followed by copper--and cobalt-containing photocatalysts. Iron-containing photocatalyst produced carbon monoxide as a major product. HS undergoing anoxic photocatalytic degradation produce hydrogen with minor hydrocarbons, and/or oxygen. It appears that better hydrogen yield is achieved when direct HS splitting takes place, as opposed to HS acting as electron donors for water splitting.

  5. Bacterial cellulose produced by a new acid-resistant strain of Gluconacetobacter genus.

    Science.gov (United States)

    Castro, Cristina; Zuluaga, Robin; Álvarez, Catalina; Putaux, Jean-Luc; Caro, Gloria; Rojas, Orlando J; Mondragon, Iñaki; Gañán, Piedad

    2012-08-01

    A bacterial strain isolated from the fermentation of Colombian homemade vinegar, Gluconacetobacter medellensis, was investigated as a new source of bacterial cellulose (BC). The BC produced from substrate media consisting of various carbon sources at different pH and incubation times was quantified. Hestrin-Schramm (HS) medium modified with glucose led to the highest BC yields followed by sucrose and fructose. Interestingly, the microorganisms are highly tolerant to low pH: an optimum yield of 4.5 g/L was achieved at pH 3.5, which is generally too low for other bacterial species to function. The cellulose microfibrils produced by the new strain were characterized by scanning and transmission electron microscopy, infrared spectroscopy X-ray diffraction and elemental analysis. The morphological, structural and chemical characteristics of the cellulose produced are similar to those expected for BC.

  6. De novo production of resveratrol from glucose or ethanol by engineered Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Li, Mingji; Kildegaard, Kanchana Rueksomtawin; Chen, Yun;

    2015-01-01

    Resveratrol is a natural antioxidant compound, used as food supplement and cosmetic ingredient. Microbial production of resveratrol has until now been achieved by supplementation of expensive substrates, p-coumaric acid or aromatic amino acids. Here we engineered the yeast Saccharomyces cerevisiae...... to produce resveratrol directly from glucose or ethanol via tyrosine intermediate. First we introduced the biosynthetic pathway, consisting of tyrosine ammonia-lyase from Herpetosiphon aurantiacus, 4-coumaryl-CoA ligase from Arabidopsis thaliana and resveratrol synthase from Vitis vinifera, and obtained 2.......73±0.05 mg L−1 resveratrol from glucose. Then we over-expressed feedback-insensitive alleles of ARO4 encoding 3-deoxy-D-arabino-heptulosonate-7-phosphate and ARO7 encoding chorismate mutase, resulting in production of 4.85±0.31 mg L−1 resveratrol from glucose as the sole carbon source. Next we improved...

  7. Fermentanomics informed amino acid supplementation of an antibody producing mammalian cell culture.

    Science.gov (United States)

    Read, Erik K; Bradley, Scott A; Smitka, Tim A; Agarabi, Cyrus D; Lute, Scott C; Brorson, Kurt A

    2013-01-01

    Fermentanomics, or a global understanding of a culture state on the molecular level empowered by advanced techniques like NMR, was employed to show that a model hybridoma culture supplied with glutamine and glucose depletes aspartate, cysteine, methionine, tryptophan, and tyrosine during antibody production. Supplementation with these amino acids prevents depletion and improves culture performance. Furthermore, no significant changes were observed in the distribution of glycans attached to the IgG3 in cultures supplemented with specific amino acids, arguing that this strategy can be implemented without fear of impact on important product quality attributes. In summary, a targeted strategy of quantifying media components and designing a supplementation strategy can improve bioprocess cell cultures when enpowered by fermentanomics tools.

  8. Measurement uncertainty of ester number, acid number and patchouli alcohol of patchouli oil produced in Yogyakarta

    Science.gov (United States)

    Istiningrum, Reni Banowati; Saepuloh, Azis; Jannah, Wirdatul; Aji, Didit Waskito

    2017-03-01

    Yogyakarta is one of patchouli oil distillation center in Indonesia. The quality of patchouli oil greatly affect its market price. Therefore, testing quality of patchouli oil parameters is an important concern, one through determination of the measurement uncertainty. This study will determine the measurement uncertainty of ester number, acid number and content of patchouli alcohol through a bottom up approach. Source contributor to measurement uncertainty of ester number is a mass of the sample, a blank and sample titration volume, the molar mass of KOH, HCl normality, and replication. While the source contributor of the measurement uncertainty of acid number is the mass of the sample, the sample titration volume, the relative mass and normality of KOH, and repetition. Determination of patchouli alcohol by Gas Chromatography considers the sources of measurement uncertainty only from repeatability because reference materials are not available.

  9. Enological characterization of natural hybrids from Saccharomyces cerevisiae and S. kudriavzevii.

    Science.gov (United States)

    González, Sara S; Gallo, Luisa; Climent, M A Dolores; Barrio, Eladio; Querol, Amparo

    2007-05-01

    The effect of yeasts on wine flavor response is of primary importance. The genus Saccharomyces, and mainly the species Saccharomyces cerevisiae, is responsible for alcoholic fermentation. Recently, several novel yeast isolates from wines have been described as hybrid yeasts between S. cerevisiae x S. kudriavzevii. We have analyzed their influence on two grape musts (Macabeo and Tempranillo) in fermentations conducted at four different temperatures (14, 18, 22 and 32 degrees C) by studying volatile compound production, sugar assimilation and other characteristics influencing the enological properties of wine caused by the impact of yeast. Hybrid yeasts behave particularly well at 14, 18 and 22 degrees C and the commercial strain of S. cerevisiae (T73) is better adapted at higher temperatures. Regarding the production of glycerol, acetic acid and malic acid, the hybrids display moderate behavior and concerning aromatic compound production, they are greater producers of higher alcohols. The behavior displayed by these hybrids in the fermentations studied in this work leads us to conclude that the use of hybrid strains can constitute an advantage in wine making.

  10. Transcriptional regulation of phospholipid biosynthesis is linked to fatty acid metabolism by an acyl-CoA-binding-protein-dependent mechanism in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Feddersen, Søren; Neergaard, Thomas B F; Knudsen, Jens;

    2007-01-01

    proteins involved in fatty acid and phospholipid synthesis (e.g. FAS1, FAS2, ACC1, OLE1, INO1 and OPI3), glycolysis and glycerol metabolism (e.g. GPD1 and TDH1), ion transport and uptake (e.g. ITR1 and HNM1) and stress response (e.g. HSP12, DDR2 and CTT1). In the present study, we show that transcription...

  11. Functional expression of a heterologous nickel-dependent, ATP-independent urease in Saccharomyces cerevisiae

    NARCIS (Netherlands)

    Milne, N.; Luttik, M.A.H.; Cueto Rojas, H.F.; Wahl, A.; Van Maris, A.J.A.; Pronk, J.T.; Daran, J.G.

    2015-01-01

    In microbial processes for production of proteins, biomass and nitrogen-containing commodity chemicals, ATP requirements for nitrogen assimilation affect product yields on the energy producing substrate. In Saccharomyces cerevisiae, a current host for heterologous protein production and potential pl

  12. Transcriptome-based characterization of interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus in lactose-grown chemostat cocultures.

    Science.gov (United States)

    Mendes, Filipa; Sieuwerts, Sander; de Hulster, Erik; Almering, Marinka J H; Luttik, Marijke A H; Pronk, Jack T; Smid, Eddy J; Bron, Peter A; Daran-Lapujade, Pascale

    2013-10-01

    Mixed populations of Saccharomyces cerevisiae yeasts and lactic acid bacteria occur in many dairy, food, and beverage fermentations, but knowledge about their interactions is incomplete. In the present study, interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus, two microorganisms that co-occur in kefir fermentations, were studied during anaerobic growth on lactose. By combining physiological and transcriptome analysis of the two strains in the cocultures, five mechanisms of interaction were identified. (i) Lb. delbrueckii subsp. bulgaricus hydrolyzes lactose, which cannot be metabolized by S. cerevisiae, to galactose and glucose. Subsequently, galactose, which cannot be metabolized by Lb. delbrueckii subsp. bulgaricus, is excreted and provides a carbon source for yeast. (ii) In pure cultures, Lb. delbrueckii subsp. bulgaricus grows only in the presence of increased CO2 concentrations. In anaerobic mixed cultures, the yeast provides this CO2 via alcoholic fermentation. (iii) Analysis of amino acid consumption from the defined medium indicated that S. cerevisiae supplied alanine to the bacterium. (iv) A mild but significant low-iron response in the yeast transcriptome, identified by DNA microarray analysis, was consistent with the chelation of iron by the lactate produced by Lb. delbrueckii subsp. bulgaricus. (v) Transcriptome analysis of Lb. delbrueckii subsp. bulgaricus in mixed cultures showed an overrepresentation of transcripts involved in lipid metabolism, suggesting either a competition of the two microorganisms for fatty acids or a response to the ethanol produced by S. cerevisiae. This study demonstrates that chemostat-based transcriptome analysis is a powerful tool to investigate microbial interactions in mixed populations.

  13. Lipid Classes, Fatty Acid Composition, and Glycerolipid Molecular Species of the Red Alga Gracilaria vermiculophylla, a Prostaglandin-Producing Seaweed.

    Science.gov (United States)

    Honda, Masaki; Ishimaru, Takashi; Itabashi, Yutaka

    2016-01-01

    The red alga Gracilaria vermiculophylla is a well-known producer of prostaglandins, such as PGE2 and PGF2α. In this study, the characteristics of glycerolipids as substrates of prostaglandin production were clarified, and the lipid classes, fatty acid composition, and glycerolipid molecular species were investigated in detail. The major lipid classes were monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), and sulfoquinovosyldiacylglycerol (SQDG), as well as phosphatidylcholine (PC), which accounted for 43.0% of the total lipid profile. Arachidonic acid (20:4n-6), a prostaglandin precursor, and palmitic acid (16:0) were the predominant fatty acids in the total lipid profile. The 20:4n-6 content was significantly high in MGDG and PC (more than 60%), and the 16:0 content was significantly high in DGDG and SQDG (more than 50%). Chiral-phase high-performance liquid chromatography determined that fatty acids were esterified at the sn-1 and sn-2 positions of those lipids. The main glycerolipid molecular species were 20:4n-6/20:4n-6 (sn-1/sn-2) for MGDG (56.5%) and PC (40.0%), and 20:4n-6/16:0 for DGDG (75.4%) and SQDG (58.4%). Thus, it was considered that the glycerolipid molecular species containing one or two 20:4n-6 were the major substrates for prostaglandin production in G. vermiculophylla.

  14. BIOCHEMICAL CHARACTERISTICS OF LACTIC ACID PRODUCING BACTERIA AND PREPARATION OF CAMEL MILK CHEESE BY USING STARTER CULTURE

    Directory of Open Access Journals (Sweden)

    T. Ahmed and R. Kanwal

    2004-04-01

    Full Text Available Lactic acid bacteria (LAB were isolated from camel milk by culturing the milk on specific media and pure culture was obtained by sub-culturing. Purification of culture was confirmed by Gram’s staining and identified by different biochemical tests. Camel milk contained lactic acid producing bacteria like Streptococci such as S. cremoris and S. lactis and Lactobacilli such as L. acidophilus. L. acidophilus grew more rapidly in camel milk than others as its growth was supported by camel milk. Ability of each strain was tested to convert lactose of milk into lactic acid. It was observed that 66% lactose was converted by S. lactis 20, whereas S. cremoris 22 and L. acidophilus 23 converted 56 and 74% lactose into lactic acid, respectively. Effect of freeze-drying was also recorded and the results showed that in all cases there was a slight decrease in the cell count before and after the freeze-drying. The decrease was approximately 0.47, 0.078 and 0.86% for S. lactis 20, S. cremoris 22 and L. acidophilus 23, respectively. Starter culture was prepared from strains isolated from camel milk. Camel and buffalo milk cheese was prepared by using starter culture. The strains isolated from camel milk were best for acid production and coagulated the milk in less time. It is concluded that cheese can be prepared successfully from camel milk and better results can be obtained by coagulating milk with starter culture.

  15. A new class of IMP dehydrogenase with a role in self-resistance of mycophenolic acid producing fungi

    DEFF Research Database (Denmark)

    Hansen, Bjarne Gram; Genee, Hans Jasper; Kaas, Christian Schrøder;

    2011-01-01

    BACKGROUND: Many secondary metabolites produced by filamentous fungi have potent biological activities, to which the producer organism must be resistant. An example of pharmaceutical interest is mycophenolic acid (MPA), an immunosuppressant molecule produced by several Penicillium species...... within the cluster. This finding suggests that the key component of MPA self resistance is likely based on the IMPDH encoded by mpaF. RESULTS: In accordance with our hypothesis, heterologous expression of mpaF dramatically increased MPA resistance in a model fungus, Aspergillus nidulans, which does...... Penicillium. All six strains were found to hold two copies of IMPDH. A cladistic analysis based on the corresponding cDNA sequences revealed a novel group constituting mpaF homologs. Interestingly, a conserved tyrosine residue in the original class of IMPDHs is replaced by a phenylalanine residue in the new...

  16. Acidogenic fermentation characteristics of different types of protein-rich substrates in food waste to produce volatile fatty acids.

    Science.gov (United States)

    Shen, Dongsheng; Yin, Jun; Yu, Xiaoqin; Wang, Meizhen; Long, Yuyang; Shentu, Jiali; Chen, Ting

    2017-03-01

    In this study, tofu and egg white, representing typical protein-rich substrates in food waste based on vegetable and animal protein, respectively, were investigated for producing volatile fatty acids (VFAs) by acidogenic fermentation. VFA production, composition, conversion pathways and microbial communities in acidogenesis from tofu and egg white with and without hydrothermal (HT) pretreatment were compared. The results showed HT pretreatment could improve the VFA production of tofu but not for egg white. The optimum VFA yields were 0.46g/gVS (tofu with HT) and 0.26g/gVS (egg white without HT), respectively. Tofu could directly produce VFAs through the Stickland reaction, while egg white was converted to lactate and VFAs simultaneously. About 30-40% of total protein remained in all groups after fermentation. Up to 50% of the unconverted soluble protein in the HT groups was protease. More lactate-producing bacteria, mainly Leuconostoc and Lactobacillus, were present during egg white fermentation.

  17. Draft Genome Sequence of Ustilago trichophora RK089, a Promising Malic Acid Producer

    Science.gov (United States)

    Zambanini, Thiemo; Buescher, Joerg M.; Meurer, Guido; Blank, Lars M.

    2016-01-01

    The basidiomycetous smut fungus Ustilago trichophora RK089 produces malate from glycerol. De novo genome sequencing revealed a 20.7-Mbp genome (301 gap-closed contigs, 246 scaffolds). A comparison to the genome of Ustilago maydis 521 revealed all essential genes for malate production from glycerol contributing to metabolic engineering for improving malate production. PMID:27469969

  18. The Bioconversion of Red Ginseng Ethanol Extract into Compound K by Saccharomyces cerevisiae HJ-014.

    Science.gov (United States)

    Choi, Hak Joo; Kim, Eun A; Kim, Dong Hee; Shin, Kwang-Soo

    2014-09-01

    A β-glucosidase producing yeast strain was isolated from Korean traditional rice wine. Based on the sequence of the YCL008c gene and analysis of the fatty acid composition, the isolate was identified as Saccharomyces cerevisiae strain HJ-014. S. cerevisiae HJ-014 produced ginsenoside Rd, F2, and compound K from the ethanol extract of red ginseng. The production was increased by shaking culture, where the bioconversion efficiency was increased 2-fold compared to standing culture. The production of ginsenoside F2 and compound K was time-dependent and thought to proceed by the transformation pathway of: red ginseng extract→Rd→F2→compound K. The optimum incubation time and concentration of red ginseng extract for the production of compound K was 96 hr and 4.5% (w/v), respectively.

  19. Urolithins, ellagic acid-derived metabolites produced by human colonic microflora, exhibit estrogenic and antiestrogenic activities.

    Science.gov (United States)

    Larrosa, Mar; González-Sarrías, Antonio; García-Conesa, María Teresa; Tomás-Barberán, Francisco A; Espín, Juan Carlos

    2006-03-08

    Urolithins A and B (hydroxy-6H-dibenzo[b,d]pyran-6-one derivatives) are colonic microflora metabolites recently proposed as biomarkers of human exposure to dietary ellagic acid derivatives. Molecular models suggest that urolithins could display estrogenic and/or antiestrogenic activity. To this purpose, both urolithins and other known phytoestrogens (genistein, daidzein, resveratrol, and enterolactone) were assayed to evaluate the capacity to induce cell proliferation on the estrogen-sensitive human breast cancer MCF-7 cells as well as the ability to bind to alpha- and beta-estrogen receptors. Both urolithins A and B showed estrogenic activity in a dose-dependent manner even at high concentrations (40 microM), without antiproliferative or toxic effects, whereas the other phytoestrogens inhibited cell proliferation at high concentrations. Overall, urolithins showed weaker estrogenic activity than the other phytoestrogens. However, both urolithins displayed slightly higher antiestrogenic activity (antagonized the growth promotion effect of 17-beta-estradiol in a dose-dependent manner) than the other phytoestrogens. The IC(50) values for the ERalpha and ERbeta binding assays were 0.4 and 0.75 microM for urolithin A; 20 and 11 microM for urolithin B; 3 and 0.02 for genistein; and 2.3 and 1 for daidzein, respectively; no binding was detected for resveratrol and enterolactone. Urolithins A and B entered into MCF-7 cells and were metabolized to yield mainly urolithin-sulfate derivatives. These results, together with previous studies regarding absorption and metabolism of dietary ellagitannins and ellagic acid in humans, suggest that the gut microflora metabolites urolithins are potential endocrine-disrupting molecules, which could resemble other described "enterophytoestrogens" (microflora-derived metabolites with estrogenic/antiestrogenic activity). Further research is warranted to evaluate the possible role of ellagitannins and ellagic acid as dietary "pro-phytoestrogens".

  20. Distribution and Orientation of Carbon Fibers in Polylactic Acid Parts Produced by Fused Deposition Modeling

    DEFF Research Database (Denmark)

    Hofstätter, Thomas; W. Gutmann, Ingomar; Koch, Thomas

    2016-01-01

    The aim of this paper is the understanding of the fiber orientation by investigations in respect to the inner configuration of a polylactic acid matrix reinforced with short carbon fibers after a fused deposition modeling extrusion process. The final parts were analyzed by X-ray, tomography, and ......, and magnetic resonance imaging allowing a resolved orientation of the fibers and distribution within the part. The research contributes to the understanding of the fiber orientation and fiber reinforcement of fused deposition modeling parts in additive manufacturing....

  1. Rat brain slices produce and liberate kynurenic acid upon exposure to L-kynurenine

    DEFF Research Database (Denmark)

    Turski, W A; Gramsbergen, J B; Traitler, H;

    1989-01-01

    aminooxyacetic acid (IC50, approximately 25 microM), and showed pronounced regional distribution (hippocampus greater than cortical areas greater than thalamus much greater than cerebellum). The conversion of L-KYN to KYNA was dependent on oxygenation and on the presence of glucose in the incubation medium...... of extracellular KYNA appears to occur at the level of L-KYN uptake and/or kynurenine transaminase, the biosynthetic enzyme of KYNA. KYNA production from L-KYN was linear up to 4 h and reached a plateau at a L-KYN concentration of 250 microM. The process was effectively inhibited by the transaminase inhibitor...

  2. Screening of Lactic Acid Bacteriafor Producing &alpha-Galactosidase from Chinese Traditional Fermented Foods

    Directory of Open Access Journals (Sweden)

    Xin-yong Du

    2012-12-01

    Full Text Available Twenty eight kinds of Chinese traditional fermented foods were collected to isolate Lactic Acid Bacteria (LAB with α-galactosidase activity, which could eliminated those α-Galactooligosaccharides (&alpha-GOS regarded as anti-nutritional factors widely existed in agricultural byproducts animal feeds. Three strains, including Lactobacillus salivarius XA1R (JX125455 and XH4B (JX125456 and Pediococcus acidilactici XS1B (JQ927329, could ferment well in soybean meal and other agricultural byproducts and had α-galactosidase activity 5.81-5.92 U/mL in soybean meal culture.

  3. Draft genome sequence of the docosahexaenoic acid producing thraustochytrid Aurantiochytrium sp. T66

    Directory of Open Access Journals (Sweden)

    Bin Liu

    2016-06-01

    Full Text Available Thraustochytrids are unicellular, marine protists, and there is a growing industrial interest in these organisms, particularly because some species, including strains belonging to the genus Aurantiochytrium, accumulate high levels of docosahexaenoic acid (DHA. Here, we report the draft genome sequence of Aurantiochytrium sp. T66 (ATCC PRA-276, with a size of 43 Mbp, and 11,683 predicted protein-coding sequences. The data has been deposited at DDBJ/EMBL/Genbank under the accession LNGJ00000000. The genome sequence will contribute new insight into DHA biosynthesis and regulation, providing a basis for metabolic engineering of thraustochytrids.

  4. A new class of IMP dehydrogenase with a role in self-resistance of mycophenolic acid producing fungi

    Directory of Open Access Journals (Sweden)

    Mortensen Uffe H

    2011-09-01

    Full Text Available Abstract Background Many secondary metabolites produced by filamentous fungi have potent biological activities, to which the producer organism must be resistant. An example of pharmaceutical interest is mycophenolic acid (MPA, an immunosuppressant molecule produced by several Penicillium species. The target of MPA is inosine-5'-monophosphate dehydrogenase (IMPDH, which catalyses the rate limiting step in the synthesis of guanine nucleotides. The recent discovery of the MPA biosynthetic gene cluster from Penicillium brevicompactum revealed an extra copy of the IMPDH-encoding gene (mpaF embedded within the cluster. This finding suggests that the key component of MPA self resistance is likely based on the IMPDH encoded by mpaF. Results In accordance with our hypothesis, heterologous expression of mpaF dramatically increased MPA resistance in a model fungus, Aspergillus nidulans, which does not produce MPA. The growth of an A. nidulans strain expressing mpaF was only marginally affected by MPA at concentrations as high as 200 μg/ml. To further substantiate the role of mpaF in MPA resistance, we searched for mpaF orthologs in six MPA producer/non-producer strains from Penicillium subgenus Penicillium. All six strains were found to hold two copies of IMPDH. A cladistic analysis based on the corresponding cDNA sequences revealed a novel group constituting mpaF homologs. Interestingly, a conserved tyrosine residue in the original class of IMPDHs is replaced by a phenylalanine residue in the new IMPDH class. Conclusions We identified a novel variant of the IMPDH-encoding gene in six different strains from Penicillium subgenus Penicillium. The novel IMPDH variant from MPA producer P. brevicompactum was shown to confer a high degree of MPA resistance when expressed in a non-producer fungus. Our study provides a basis for understanding the molecular mechanism of MPA resistance and has relevance for biotechnological and pharmaceutical applications.

  5. Occurrence of indole-3-acetic Acid-producing bacteria on pear trees and their association with fruit russet.

    Science.gov (United States)

    Lindow, S E; Desurmont, C; Elkins, R; McGourty, G; Clark, E; Brandl, M T

    1998-11-01

    ABSTRACT A relatively high percentage of epiphytic bacteria on pear leaf and fruit surfaces had the ability to produce indole-3-acetic acid (IAA) in culture media supplemented with tryptophan. While over 50% of the strains produced at least small amounts of IAA in culture, about 25% of the strains exhibited high IAA production as evidenced by both colorimetric and high-performance liquid chromatography analysis of culture supernatants. A majority of the strains that produced high amounts of IAA were identified as Erwinia herbicola (Pantoea agglomerans), while some strains of Pseudomonas syringae, Pseudomonas viridiflava, Pseudomonas fluorescens, Pseudomonas putida, and Rahnella aquaticus that produced high amounts of IAA also were found on pear. Fruit russeting was significantly increased in 39 out of 46 trials over an 8-year period in which IAA-producing bacteria were applied to trees compared with control trees. A linear relationship was observed between fruit russet severity and the logarithm of the population size of different IAA-producing bacteria on trees in the 30 days after inoculation, when normalized for the amount of IAA produced by each strain in culture. On average, the severity of fruit russet was only about 77% that on control trees when trees were treated at the time of bloom with Pseudomonas fluorescens strain A506, which does not produce IAA. Both total bacterial populations on pear in the 30-day period following full bloom and fruit russet severity varied greatly from year to year and in different commercial orchards over a 10-year period. There was a strong linear correlation between the logarithm of total bacterial population sizes and fruit russet severity.

  6. The γ-aminobutyric acid-producing ability under low pH conditions of lactic acid bacteria isolated from traditional fermented foods of Ishikawa Prefecture, Japan, with a strong ability to produce ACE-inhibitory peptides

    Directory of Open Access Journals (Sweden)

    Florin Barla

    2016-06-01

    Full Text Available Many traditional fermented products are onsumed in Ishikawa Prefecture, Japan, such as kaburazushi, narezushi, konkazuke, and ishiru. Various kinds of lactic acid bacteria (LAB are associated with their fermentation, however, characterization of LAB has not yet been elucidated in detail. In this study, we evaluated 53 isolates of LAB from various traditional fermented foods by taxonomic classification at the species level by analyzing the 16S ribosomal RNA gene (rDNA sequences and carbohydrate assimilation abilities. We screened isolates that exhibited high angiotensin-converting enzyme (ACE inhibitory activities in skim milk or soy protein media and produced high γ-aminobutyric acid (GABA concentrations in culture supernatants when grown in de Man Rogosa Sharpe broth in the presence of 1% (w/v glutamic acid. The results revealed that 10 isolates, i.e., Lactobacillus buchneri (2 isolates, Lactobacillus brevis (6 isolates, and Weissella hellenica (2 isolates had a high GABA-producing ability of >500 mg/100 ml after 72 h of incubation at 35 °C. The ACE inhibitory activity of the whey cultured with milk protein by using L. brevis (3 isolates, L. buchneri (2 isolates, and W. hellenica (2 isolates was stronger than that of all whey cultured with soy protein media, and these IC50 were < 1 mg protein/ml. Three of 10 isolates had high GABA-producing activities at pH 3, suggesting that they could be powerful candidates for use in the fermentation of food materials having low pH.

  7. Inhibition of fatty acid binding proteins elevates brain anandamide levels and produces analgesia.

    Directory of Open Access Journals (Sweden)

    Martin Kaczocha

    Full Text Available The endocannabinoid anandamide (AEA is an antinociceptive lipid that is inactivated through cellular uptake and subsequent catabolism by fatty acid amide hydrolase (FAAH. Fatty acid binding proteins (FABPs are intracellular carriers that deliver AEA and related N-acylethanolamines (NAEs to FAAH for hydrolysis. The mammalian brain expresses three FABP subtypes: FABP3, FABP5, and FABP7. Recent work from our group has revealed that pharmacological inhibition of FABPs reduces inflammatory pain in mice. The goal of the current work was to explore the effects of FABP inhibition upon nociception in diverse models of pain. We developed inhibitors with differential affinities for FABPs to elucidate the subtype(s that contributes to the antinociceptive effects of FABP inhibitors. Inhibition of FABPs reduced nociception associated with inflammatory, visceral, and neuropathic pain. The antinociceptive effects of FABP inhibitors mirrored their affinities for FABP5, while binding to FABP3 and FABP7 was not a predictor of in vivo efficacy. The antinociceptive effects of FABP inhibitors were mediated by cannabinoid receptor 1 (CB1 and peroxisome proliferator-activated receptor alpha (PPARα and FABP inhibition elevated brain levels of AEA, providing the first direct evidence that FABPs regulate brain endocannabinoid tone. These results highlight FABPs as novel targets for the development of analgesic and anti-inflammatory therapeutics.

  8. Secondary economic impact of acid deposition control legislation in six coal producing states: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Scott, M.J.; Guthrie, S.J.

    1988-12-01

    Among the difficult policy questions on the US environmental agenda is what to do about emissions to the earth's atmosphere of pollutants that may result in ''acid rain''. The Congress has considered several pieces of legislation spelling out potential approaches to the problem and setting goals for emission reduction, mostly emphasizing the control of oxides of sulfur and nitrogen. Significant policy concern is the dollar costs to the nation's economy of achieving the intended effects of the legislation and the potential impacts on economic activity---in particular, losses of both coal mining and secondary service sector employment in states and regions dependent on the mining of high sulfur coal. There are several direct economic effects of regulations such as the acid rain control legislation. One of the more obvious effects was the switching from high sulfur coal to low sulfur coal. This would result in increases in employment and coal business procurements in low sulfur coal mining regions, but also would result in lower employment and lower coal business procurements in high sulfur coal mining areas. The potential negative effects are the immediate policy concern and are the focus of this report. 15 refs., 1 fig., 17 tabs.

  9. Combination of Successive Alkalinity Producing System (SAPS) and Aeration for Passive Treatment of Highly Acidic Mine Drainage

    Science.gov (United States)

    Oh, C.; Ji, S.

    2015-12-01

    Passive treatment system has been widely used for remediation of mine drainage since its advantage of low installation and maintenance cost. The system, however, has also a disadvantage in assuring remediation and management efficiency if the drainage is highly acidic mine drainage. To remediate acid mine drainage (AMD) especially showing high acidity, passive treatment system which consists of successive alkalinity producing system (SAPS) and subsequent aeration pond was proposed and its mechanisms and efficiency was evaluated in this research. Target AMD was obtained from Waryong coal mine and showed typical characteristics of AMD having high metal concentration and low pH (acidity > 300 mg/L as CaCO3). Four experimental cases were conducted; untreated, treated with SAPS, treated with aeration, treated with SAPS and aeration to compare role and mechanism of each unit. Between organic matter and limestone layer which constitute SAPS, the former eliminated most of Fe(III) and Al in the AMD so that the latter was kept from being clogged by precipitates. Net acidity of the AMD rapidly decreased by supplement of alkalinity at the limestone layer. A primary function of SAPS, producing alkalinity constantly without clogging, was attained due to addition a portion of limestone particle into the organic matter layer. The discharge from SAPS had low ORP and DO values because of an anaerobic environment formed at the organic matter layer although its alkalinity was increased. This water quality was unfavorable for Fe(II) to be oxidized. Installation of aeration pond after SAPS, therefore, could be effective way of enhancing oxidation rate of Fe(II). Among the experimental cases, the combination of SAPS and aeration pond was only able to remediate the AMD. This concluded that to remediate highly acidic mine drainage with passive treatment system, three critical conditions were required; pre-precipitation of Fe(III) and Al at organic matter layer in SAPS, constant alkalinity

  10. Lipase-catalyzed acidolysis of canola oil with caprylic acid to produce medium-, long- and medium-chain-type structured lipids

    DEFF Research Database (Denmark)

    Wang, Yingyao; Xia, Luan; Xu, Xuebing

    2012-01-01

    Lipase-catalyzed acidolysis of canola oil with caprylic acid was performed to produce structured lipids (SLs) containing medium-chain fatty acid (M) at position sn-1,3 and long-chain fatty acid (L) at the sn-2 position in a solvent-free system. Six commercial lipases from different sources were s...

  11. Effect of Indole-3-Acetic Acid-Producing Bacteria on Phytoremediation of Soil Contaminated with Phenanthrene and Anthracene by Mungbean

    Directory of Open Access Journals (Sweden)

    Waraporn Chouychai

    2016-07-01

    Full Text Available The use of indole-3-acetic acid (IAA-producing bacteria isolated from non-contaminated weed rhizosphere to enhance plant growth and PAH phytoremediation capacity was investigated. IAA-producing bacterial isolates, designated NSRU1, NSRU2, and NSRU3, were isolated from the rhizosphere of Eleusine indica (Poaceae and Chromolaena odorata (Asteraceae. The isolates were able to produce IAA in nutrient broth. However, when grown in the presence of 100 mg/l of either phenanthrene or anthracene, the amount of IAA produced by each isolate was reduced significantly. Mungbean seedlings were planted in 100 mg/kg phenanthrene- or anthracene-contaminated soil without or with inoculation of ≈106 CFU/g dry soil with one of the bacterial isolates. Inoculation with either NSRU1 or NSRU2 was effective at enhancing shoot length of mungbean in phenanthrene-contaminated soil on day 16. Also, inoculation with isolate NSRU1 led to increased root dry weight of mungbean in phenanthrene-contaminated soil on day 30. Phenanthrene and anthracene degradation on day 16 and 30 in planted and inoculated soil ranged between 92 - 93.8% and 92.2 - 94.1%, respectively, which were not significantly different from planted and uninoculated soil (93.9 and 94.9%. These data showed that IAA-producing bacteria could enhance plant growth, but was unable to increase PAH biodegradation under the conditions tested.

  12. Antibiotics suppress Cyp3a in the mouse liver by reducing lithocholic acid-producing intestinal flora.

    Science.gov (United States)

    Toda, Takahiro; Ohi, Kanna; Kudo, Toshiyuki; Yoshida, Tomoyuki; Ikarashi, Nobutomo; Ito, Kiyomi; Sugiyama, Kiyoshi

    2009-05-01

    We previously demonstrated that ciprofloxacin (CPX), a new quinolone antibiotic, suppresses Cyp3a in the mouse liver by reducing the hepatic level of lithocholic acid (LCA) produced by intestinal flora. The present study investigated the possibility that other antibiotics with antibacterial activity against LCA-producing bacteria also cause a decrease in the LCA level in the liver, leading to reduced expression of Cyp3a11. While the mRNA expression of Cyp3a11 in the liver was significantly reduced when SPF mice were administered antibiotics such as ampicillin, CPX, levofloxacin, or a combination of vancomycin and imipenem, no significant changes were observed after antibiotic treatment of GF mice lacking intestinal flora. LCA-producing bacteria in the feces as well as the hepatic level of the taurine conjugate of LCA were significantly reduced in the antibiotic-treated SPF mice, suggesting that the decrease in Cyp3a11 expression can be attributed to the reduction in LCA-producing intestinal flora following antibiotic administration. These results suggest that the administration of antibiotics with activity against LCA-producing bacteria can also cause a decrease in the LCA level in humans, which may lower CYP3A4 expression. The intestinal flora are reported to be altered not only by drugs, such as antibiotics, but also by stress, disease, and age. The findings of the present study suggest that these changes in intestinal flora could modify CYP expression and contribute to the individual differences in pharmacokinetics.

  13. Identification of urolithin a as a metabolite produced by human colon microflora from ellagic acid and related compounds.

    Science.gov (United States)

    Cerdá, Begoña; Periago, Paula; Espín, Juan Carlos; Tomás-Barberán, Francisco A

    2005-07-13

    Dietary ellagic acid and related polyphenols are metabolized in humans to dibenzopyran-6-one derivatives, and the microbial origin of these metabolites has been suggested. However, this has not been demonstrated so far. Fecal samples donated by six volunteers were incubated under anaerobic conditions, and aliquots were used to evaluate the fecal metabolism of ellagic acid, the ellagitannin punicalagin, and an ellagitannin rich extract from walnuts. The isoflavone daidzein was also incubated with the same fecal samples to follow the production of the microbial metabolites previously reported (dihydrogenistein, O-demethylangolensin, and equol) as a positive control of the system and to evaluate similarities between isoflavone and ellagic acid fecal flora metabolism. After fermentation the metabolite "urolithin A" (3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one) was produced from ellagic acid, punicalagin, and the ellagitannin extract in all the fecal cultures from different volunteers, but with very different production rates and concentrations. This large variability in the concentration of metabolite and kinetics of metabolite production is consistent with the large variability found in the excretion of these metabolites in urine in vivo after human consumption of ellagitannins, and with differences in the composition of the fecal microflora. No correlation between isoflavone and ellagic acid metabolism by fecal microflora was observed. The present study confirms the microbial origin of the recently reported in vivo generated hydroxy-6H-dibenzo[b,d]pyran-6-one derivatives in humans and is a further step in the study of the bioavailability and metabolism of ellagic acid and ellagitannins.

  14. Potential of bacteriocin-producing lactic acid bacteria for safety improvements of traditional Thai fermented meat and human health.

    Science.gov (United States)

    Swetwiwathana, Adisorn; Visessanguan, Wonnop

    2015-11-01

    Lactic acid bacteria (LAB) are very important in converting of agricultural products into safe, delicious and shelf stable foods for human consumption. The preservative activity of LAB in foods is mainly attributed to the production of anti-microbial metabolites such as organic acids and bacteriocins which enables them to grow and control the growth of pathogens and spoilage microorganisms. Besides ensuring safety, bacteriocin-producing LAB with their probiotic potentials could also be emerging as a means to develop functional meat products with desirable health benefits. Nevertheless, to be qualified as a candidate probiotic culture, other prerequisite probiotic properties of bacteriocin-producing LAB have to be assessed according to regulatory guidelines for probiotics. Nham is an indigenous fermented sausage of Thailand that has gained popularity and acceptance among Thais. Since Nham is made from raw meat and is usually consumed without cooking, risks due to undesirable microorganisms such as Salmonella spp., Staphylococcus aureus, and Listeria monocytogenes, are frequently observed. With an ultimate goal to produce safer and healthier product, our research attempts on the development of a variety of new Nham products are discussed.

  15. Simple, effective protein extraction method and proteomics analysis from polyunsaturated fatty acids-producing micro-organisms.

    Science.gov (United States)

    Ling, Xueping; Guo, Jing; Zheng, Chuqiang; Ye, Chiming; Lu, Yinghua; Pan, Xueshan; Chen, Zhengqi; Ng, I-Son

    2015-12-01

    Polyunsaturated fatty acids (PUFAs) are valuable ingredients in the food and pharmaceutical products due to their beneficial influence on human health. Most studies paid attention on the production of PUFAs from oleaginous micro-organisms but seldom on the comparative proteomics of cells. In the study, three methods (i.e., cold shock, acetone precipitation and ethanol precipitation) for lipid removal from crude protein extracts were applied in different PUFAs-producing micro-organisms. Among the selective strains, Schizochytrium was used as an oleaginous strain with high lipid of 60.3 (w/w%) in biomass. The Mortierella alpina and Cunninghamella echinulata were chosen as the low-lipid-content strains with 25.8 (w/w%) and 21.8 (w/w%) of lipid in biomass, respectively. The cold shock resulted as the most effective method for lipid removed, thus obtained higher protein amount for Schizochytrium. Moreover, from the comparative proteomics for the three PUFAs-producing strains, it showed more significant proteins of up or down-regulation were explored under cold shock treatment. Therefore, the essential proteins (i.e., polyunsaturated fatty acid synthase) and regulating proteins were observed. In conclusion, this study provides a valuable and practical approach for analysis of high PUFAs-producing strains at the proteomics level, and would further accelerate the understanding of the metabolic flux in oleaginous micro-organisms.

  16. The lactic acid bacterium Pediococcus acidilactici suppresses autoimmune encephalomyelitis by inducing IL-10-producing regulatory T cells.

    Directory of Open Access Journals (Sweden)

    Kazushiro Takata

    Full Text Available BACKGROUND: Certain intestinal microflora are thought to regulate the systemic immune response. Lactic acid bacteria are one of the most studied bacteria in terms of their beneficial effects on health and autoimmune diseases; one of which is Multiple sclerosis (MS which affects the central nervous system. We investigated whether the lactic acid bacterium Pediococcus acidilactici, which comprises human commensal bacteria, has beneficial effects on experimental autoimmune encephalomyelitis (EAE, an animal model of MS. METHODOLOGY/PRINCIPAL FINDINGS: P. acidilactici R037 was orally administered to EAE mice to investigate the effects of R037. R037 treatment suppressed clinical EAE severity as prophylaxis and therapy. The antigen-specific production of inflammatory cytokines was inhibited in R037-treated mice. A significant increase in the number of CD4(+ Interleukin (IL-10-producing cells was observed in the mesenteric lymph nodes (MLNs and spleens isolated from R037-treated naive mice, while no increase was observed in the number of these cells in the lamina propria. Because only a slight increase in the CD4(+Foxp3(+ cells was observed in MLNs, R037 may primarily induce Foxp3(- IL10-producing T regulatory type 1 (Tr1 cells in MLNs, which contribute to the beneficial effect of R037 on EAE. CONCLUSIONS/SIGNIFICANCE: An orally administered single strain of P. acidilactici R037 ameliorates EAE by inducing IL10-producing Tr1 cells. Our findings indicate the therapeutic potential of the oral administration of R037 for treating multiple sclerosis.

  17. Biosynthesis of fluorothreonine and fluoroacetic acid by the thienamycin producer, Streptomyces cattleya.

    Science.gov (United States)

    Sanada, M; Miyano, T; Iwadare, S; Williamson, J M; Arison, B H; Smith, J L; Douglas, A W; Liesch, J M; Inamine, E

    1986-02-01

    An antimetabolite, THX, was isolated from fermentation broths of the thienamycin producer, Streptomyces cattleya, when the organism was grown in the presence of a fluorine-containing substrate. THX was subsequently identified as one of the four possible stereoisomers of 4-fluorothreonine. Inorganic fluoride or any one of a number of organofluorine compounds can be used as precursors of 4-fluorothreonine. In addition, 19F NMR has provided evidence that the organism synthesizes fluoroacetate under the same fermentation conditions. The in vitro antibacterial spectrum of 4-fluorothreonine is also presented.

  18. Hairy Root Cultures of Gymnema sylvestre R. Br. to Produce Gymnemic Acid.

    Science.gov (United States)

    Rajashekar, J; Kumar, Vadlapudi; Veerashree, V; Poornima, D V; Sannabommaji, Torankumar; Gajula, Hari; Giridhara, B

    2016-01-01

    Gymnema sylvestre R. Br. (Asclepiadaceae) is an endangered species extensively used in the management of diabetes, obesity, and treatment of various diseases. Uncontrolled exploitation to meet the increasing demand and low seed viability hastens the disappearance of the plant from its natural habitat. Hairy root culture provides a suitable alternative for the enhanced production of active principles. The current protocol provides the optimized culture conditions for the establishment of hairy root cultures and elicitation studies and also confirmation of stable integration of A. rhizogenes plasmid T-DNA into host genetic material by PCR and RT-PCR. Furthermore, it also discusses the suitable methods for the extraction procedures, and qualitative and quantitative analysis of gymnemic acid by HPTLC and HPLC.

  19. Medical and Personal Care Applications of Bacteriocins Produced by Lactic Acid Bacteria

    Science.gov (United States)

    Dicks, L. M. T.; Heunis, T. D. J.; van Staden, D. A.; Brand, A.; Noll, K. Sutyak; Chikindas, M. L.

    The frequent use of antibiotics has led to a crisis in the antibiotic ­resistance of pathogens associated with humans and animals. Antibiotic resistance and the emergence of multiresistant bacterial pathogens have led to the investigation of alternative antimicrobial agents to treat and prevent infections in both humans and animals. Research on antimicrobial peptides, with a special interest on bacteriocins of lactic acid bacteria, is entering a new era with novel applications other than food preservation. Many scientists are now focusing on the application of these peptides in medicinal and personal care products. However, it is difficult to assess the success of such ventures due to the dearth of information that has been published and the lack of clinical trials.

  20. Volatile fatty acids produced by co-fermentation of waste activated sludge and henna plant biomass.

    Science.gov (United States)

    Huang, Jingang; Zhou, Rongbing; Chen, Jianjun; Han, Wei; Chen, Yi; Wen, Yue; Tang, Junhong

    2016-07-01

    Anaerobic co-fermentation of waste activated sludge (WAS) and henna plant biomass (HPB) for the enhanced production of volatile fatty acids (VFAs) was investigated. The results indicated that VFAs was the main constituents of the released organics; the accumulation of VFAs was much higher than that of soluble carbohydrates and proteins. HPB was an advantageous substrate compared to WAS for VFAs production; and the maximum VFAs concentration in an HPB mono-fermentation system was about 2.6-fold that in a WAS mono-fermentation system. In co-fermentation systems, VFAs accumulation was positively related to the proportion of HPB in the mixed substrate, and the accumulated VFAs concentrations doubled when HPB was increased from 25% to 75%. HPB not only adjust the C/N ratio; the associated and/or released lawsone might also have a positive electron-shuttling effect on VFAs production.

  1. Mutualistic fungal endophytes produce phytohormones and organic acids that promote japonica rice plant growth under prolonged heat stress.

    Science.gov (United States)

    Waqas, Muhammad; Khan, Abdul Latif; Shahzad, Raheem; Ullah, Ihsan; Khan, Abdur Rahim; Lee, In-Jung

    2015-12-01

    This study identifies the potential role in heat-stress mitigation of phytohormones and other secondary metabolites produced by the endophytic fungus Paecilomyces formosus LWL1 in japonica rice cultivar Dongjin. The japonica rice was grown in controlled chamber conditions with and without P. formosus LWL1 under no stress (NS) and prolonged heat stress (HS) conditions. Endophytic association under NS and HS conditions significantly improved plant growth attributes, such as plant height, fresh weight, dry weight, and chlorophyll content. Furthermore, P. formosus LWL1 protected the rice plants from HS compared with controls, indicated by the lower endogenous level of stress-signaling compounds such as abscisic acid (25.71%) and jasmonic acid (34.57%) and the increase in total protein content (18.76%-33.22%). Such fungal endophytes may be helpful for sustainable crop production under high environmental temperatures.

  2. Cinnamic acid 4-hydroxylase mechanism-based inactivation by psoralen derivatives: cloning and characterization of a C4H from a psoralen producing plant-Ruta graveolens-exhibiting low sensitivity to psoralen inactivation.

    Science.gov (United States)

    Gravot, Antoine; Larbat, Romain; Hehn, Alain; Lièvre, Karine; Gontier, Eric; Goergen, Jean Louis; Bourgaud, Frédéric

    2004-02-01

    Cinnamate 4-hydroxylase (C4H, EC 1.14.13.11) complete cDNA was cloned from the leaves of Ruta graveolens, a psoralen producing plant. The recombinant enzyme (classified CYP73A32) was expressed in Saccharomyces cerevisiae. Mechanism-based inactivation was investigated using various psoralen derivatives. Only psoralen and 8-methoxypsoralen were found to inactivate C4H. The inactivation was dependent on the presence of NADPH, time of pre-incubation, and inhibitor concentration. Inactivation stoichiometry was 0.9 (+/-0.2) for CYP73A1 and 1.1 (+/-0.2) for CYP73A32. SDS-PAGE analysis demonstrated that [3H]psoralen was irreversibly bound to the C4H apoprotein. K(i) and k(inact) for psoralen and 8-methoxypsoralen inactivation on the two C4H revealed a lower sensitivity for CYP73A32 compared to CYP73A1. Inactivation kinetics were also determined for CYP73A10, a C4H from another furocoumarin-producing plant, Petroselinum crispum. This enzyme was found to behave like CYP73A32, with a weak sensitivity to psoralen and 8-MOP inactivation. Cinnamic acid hydroxylation is a key step in the biosynthesis of phenylpropanoid compounds, psoralen derivatives included. Our results suggest a possible evolution of R. graveolens and P. crispum C4H that might tolerate substantial levels of psoralen derivatives in the cytoplasmic compartment without a depletive effect on C4H and the general phenylpropanoid metabolism.

  3. Kinetic modeling, production and characterization of an acidic lipase produced by Enterococcus durans NCIM5427 from fish waste

    OpenAIRE

    2013-01-01

    Enterococcus durans NCIM5427 (ED-27), capable of producing an intracellular acid stable lipase, was isolated from fish processing waste. Its growth and subsequent lipase production was optimized by Box Behneken design (optimized conditions: 5 % v/v fish waste oil (FWO), 0.10 mg/ml fish waste protein hydrolysates (FWPH) at 48 h of fermentation time). Under optimized conditions, ED-27 showed a 3.0 fold increase (207.6 U/ml to 612.53 U/ml) in lipase production, as compared to un-optimized condit...

  4. Screening of Bacteriocin-producing Lactic Acid Bacteria%产细菌素乳酸菌的筛选

    Institute of Scientific and Technical Information of China (English)

    胡欣洁; 刘云; 邓清云

    2012-01-01

    [Objective]To develop a strain of high-efficient bacteriocin with broader antimicrobial spectrum as natural preservative. [ Method] With pickles and yoghurt as raw materials, the bacteria, which could inhibit the indicator bacteria, was screened from the test materials by using MRS selective medium, and whether the bacteria could produce bacteriocin or not was determined by the tests of excluding acid inhibition, hydrogen peroxide inhibition and protease sensitivity. [Result]The screened strain was identified to be lactic acid bacteria, the produced bacteriocin had inhibitive effect against gram-negative and gram-positive bacteria, and it was a strain of lactic acid bacteria with iroad spectrum and the ability of bacteriocin-producing. [Conclusion]The bacteriocin-producing lactic acid bacteria had important roles in inhibiting various pathogens and food decay.%[目的]开发出更加高效、抑菌谱更广、可做天然防腐剂的细菌素.[方法]以泡菜、酸奶为原料,利用MRS选择培养基从试材中筛选出能够抑制指示菌的细菌,通过排除酸抑制作用、过氧化氢抑制作用和蛋白酶敏感性试验证明该菌株是否产生有抑菌作用的细菌素.[结果]筛选得到的菌株经鉴定证明是乳酸菌,其产生的细菌素对革兰氏阴性菌和革兰氏阳性菌都有抑制作用,是一株产广谱细菌素的乳酸菌.[结论]筛选得出的乳酸菌细菌素在抑制各种病原菌和食品腐败等方面具有重要作用.

  5. Molecular Identification of Lactic Acid Bacteria Producing Antimicrobial Agents from Bakasang, An Indonesian Traditional Fermented Fish Product

    Directory of Open Access Journals (Sweden)

    Helen Joan Lawalata

    2015-11-01

    Full Text Available AbstractTwenty seven strains of lactic acid bacteria (LAB were isolated from bakasang, Indonesian traditional fermented fish product. In general, LAB have inhibitory activity againts pathogenic bacteria and spoilage bacteria. Screening for antimicrobia activity of isolates were performed with well-diffusion method. One isolate that was designed as Pediococcus BksC24 was the strongest against bacteria pathogenic and spoilage bacteria. This strain was further identified by 16S rRNA gen sequence comparison. Isolates LAB producing antimicrobial agents from bakasang were identified as Pediococcus acidilactici.Keywords : Bakasang, LAB, antimicrobial, phenotypic characteristics, 16S rRNA gene

  6. Lipozyme RM IM-catalyzed acidolysis of Cinnamomum camphora seed oil with oleic acid to produce human milk fat substitutes enriched in medium-chain fatty acids.

    Science.gov (United States)

    Zou, Xian-Guo; Hu, Jiang-Ning; Zhao, Man-Li; Zhu, Xue-Mei; Li, Hong-Yan; Liu, Xiao-Ru; Liu, Rong; Deng, Ze-Yuan

    2014-10-29

    In the present study, a human milk fat substitute (HMFS) enriched in medium-chain fatty acids (MCFAs) was synthesized through acidolysis reaction from Cinnamomum camphora seed oil (CCSO) with oleic acid in a solvent-free system. A commercial immobilized lipase, Lipozyme RM IM, from Rhizomucor miehei, was facilitated as a biocatalyst. Effects of different reaction conditions, including substrate molar ratio, enzyme concentration, reaction temperature, and reaction time were investigated using response surface methodology (RSM) to obtain the optimal oleic acid incorporation. After optimization, results showed that the maximal incorporation of oleic acid into HMFS was 59.68%. Compared with CCSO, medium-chain fatty acids at the sn-2 position of HMFS accounted for >70%, whereas oleic acid was occupied predominantly at the sn-1,3 position (78.69%). Meanwhile, triacylglycerol (TAG) components of OCO (23.93%), CCO (14.94%), LaCO (13.58%), OLaO (12.66%), and OOO (11.13%) were determined as the major TAG species in HMFS. The final optimal reaction conditions were carried out as follows: substrate molar ratio (oleic acid/CCSO), 5:1; enzyme concentration, 12.5% (w/w total reactants); reaction temperature, 60 °C; and reaction time, 28 h. The reusability of Lipozyme RM IM in the acidolysis reaction was also evaluated, and it was found that it could be reused up to 9 times without significant loss of activities. Urea inclusion method was used to separate and purify the synthetic product. As the ratio of HMFS/urea increased to 1:2, the acid value lowered to the minimum. In a scale-up experiment, the contents of TAG and total tocopherols in HMFS (modified CCSO) were 77.28% and 12.27 mg/100 g, respectively. All of the physicochemical indices of purified product were within food standards. Therefore, such a MCFA-enriched HMFS produced by using the acidolysis method might have potential application in the infant formula industry.

  7. Introducing a new breed of wine yeast: interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast and Saccharomyces mikatae.

    Directory of Open Access Journals (Sweden)

    Jennifer R Bellon

    Full Text Available Interspecific hybrids are commonplace in agriculture and horticulture; bread wheat and grapefruit are but two examples. The benefits derived from interspecific hybridisation include the potential of generating advantageous transgressive phenotypes. This paper describes the generation of a new breed of wine yeast by interspecific hybridisation between a commercial Saccharomyces cerevisiae wine yeast strain and Saccharomyces mikatae, a species hitherto not associated with industrial fermentation environs. While commercially available wine yeast strains provide consistent and reliable fermentations, wines produced using single inocula are thought to lack the sensory complexity and rounded palate structure obtained from spontaneous fermentations. In contrast, interspecific yeast hybrids have the potential to deliver increased complexity to wine sensory properties and alternative wine styles through the formation of novel, and wider ranging, yeast volatile fermentation metabolite profiles, whilst maintaining the robustness of the wine yeast parent. Screening of newly generated hybrids from a cross between a S. cerevisiae wine yeast and S. mikatae (closely-related but ecologically distant members of the Saccharomyces sensu stricto clade, has identified progeny with robust fermentation properties and winemaking potential. Chemical analysis showed that, relative to the S. cerevisiae wine yeast parent, hybrids produced wines with different concentrations of volatile metabolites that are known to contribute to wine flavour and aroma, including flavour compounds associated with non-Saccharomyces species. The new S. cerevisiae x S. mikatae hybrids have the potential to produce complex wines akin to products of spontaneous fermentation while giving winemakers the safeguard of an inoculated ferment.

  8. Flow cytometric viability assessment of lactic acid bacteria starter cultures produced by fluidized bed drying.

    Science.gov (United States)

    Bensch, Gerald; Rüger, Marc; Wassermann, Magdalena; Weinholz, Susann; Reichl, Udo; Cordes, Christiana

    2014-06-01

    For starter culture production, fluidized bed drying is an efficient and cost-effective alternative to the most frequently used freeze drying method. However, fluidized bed drying also poses damaging or lethal stress to bacteria. Therefore, investigation of impact of process variables and conditions on viability of starter cultures produced by fluidized bed drying is of major interest. Viability of bacteria is most frequently assessed by plate counting. While reproductive growth of cells can be characterized by the number of colony-forming units, it cannot provide the number of viable-but-nonculturable cells. However, in starter cultures, these cells still contribute to the fermentation during food production. In this study, flow cytometry was applied to assess viability of Lactobacillus plantarum starter cultures by membrane integrity analysis using SYBR®Green I and propidium iodide staining. The enumeration method established allowed for rapid, precise and sensitive determination of viable cell concentration, and was used to investigate effects of fluidized bed drying and storage on viability of L. plantarum. Drying caused substantial membrane damage on cells, most likely due to dehydration and oxidative stress. Nevertheless, high bacterial survival rates were obtained, and granulates contained in the average 2.7 × 10(9) viable cells/g. Furthermore, increased temperatures reduced viability of bacteria during storage. Differences in results of flow cytometry and plate counting suggested an occurrence of viable-but-nonculturable cells during storage. Overall, flow cytometric viability assessment is highly feasible for rapid routine in-process control in production of L. plantarum starter cultures, produced by fluidized bed drying.

  9. Influence of viscosity and uronic acid composition of alginates on the properties of alginate films and microspheres produced by emulsification.

    Science.gov (United States)

    Lee, Huey Ying; Chan, Lai Wah; Dolzhenko, Anton V; Heng, Paul Wan Sia

    2006-12-01

    This study investigated the influence of viscosity and uronic acid composition of alginates on the properties of alginate films and microspheres produced by emulsification. Tensile properties of films were determined while the yield, size, drug contents and release characteristics of the microspheres were examined. Tensile properties of calcium alginate matrix were significantly affected by the orientation and arrangement of the polymer chains. High viscosity alginates gave rise to higher yields and bigger microspheres. Generally, microspheres with high drug content and slower rate of drug release had high Ca2+ contents and were produced from alginates of higher viscosity. Within an alginate microsphere batch, small sized microsphere fractions had higher drug contents but showed faster drug release rates. Microspheres having a defined size range revealed great dependence of encapsulation efficiency and drug release rates on viscosity and extent of Ca2+-alginate interaction. Viscosity appeared to exert a predominant influence on the microsphere properties.

  10. Phosphatidic acid produced by phospholipase D is required for tobacco pollen tube growth.

    Science.gov (United States)

    Potocký, Martin; Eliás, Marek; Profotová, Bronislava; Novotná, Zuzana; Valentová, Olga; Zárský, Viktor

    2003-05-01

    Phospholipase D (PLD) and its product phosphatidic acid (PA) are involved in a number of signalling pathways regulating cell proliferation, membrane vesicle trafficking and defence responses in eukaryotic cells. Here we report that PLD and PA have a role in the process of polarised plant cell expansion as represented by pollen tube growth. Both phosphatidylinositol-4,5-bisphosphate-dependent and independent PLD activities were identified in pollen tube extracts, and activity levels during pollen tube germination and growth were measured. PLD-mediated PA production in vivo can be blocked by primary alcohols, which serve as a substrate for the transphosphatidylation reaction. Both pollen germination and tube growth are stopped in the presence 0.5% 1-butanol, whereas secondary and tertiary isomers do not show any effect. This inhibition could be overcome by addition of exogenous PA-containing liposomes. In the absence of n-butanol, addition of a micromolar concentration of PA specifically stimulates pollen germination and tube elongation. Furthermore, a recently established link between PLD and microtubule dynamics was supported by taxol-mediated partial rescue of the 1-butanol-inhibited pollen tubes. The potential signalling role for PLD-derived PA in plant cell expansion is discussed.

  11. Isolation and Selection of Anti-Candida albicans Producing Lactic Acid Bacteria

    Directory of Open Access Journals (Sweden)

    Monthon LERTCANAWANICHAKUL

    2005-06-01

    Full Text Available The forty isolates of lactic acid bacteria (LAB were obtained from various fermented foods. The cross streak plate method was used to preliminary screen for antimicrobial activity. LAB were isolated by selective medium, Mann Rogosa Sharpe (MRS. Most of the isolates showed inhibition against Staphylococcus aureus TISTR 517, Bacillus subtilis TISTR 008, Micrococcus luteus TISTR 884, Escherichia coli TISTR 887, Pseudomonas aeruginosa TISTR 781, and Candida albicans DMST 5239. Only sterile culture supernatant of isolate No. L14, later identified as Lactococcus lactis, showed antifungal activity by means of agar well diffusion assay. The activity was stable during heat treatment and was retained even after autoclaving at 121 °C for 15 minutes. Maximum activity was observed at pH values between 2.5-4.0, and was lost at higher pH values. The anti-C. albicans activity was fully regained after readjustment of the pH to the initial value (pH 3.5.

  12. 酿酒酵母和嗜鞣管囊酵母对稀酸水解抑制物的耐受性%Tolerance of Saccharomyces cerevisiae and Pachysolen tannophilus to Diluted Acid Hydrolysis Inhibitor

    Institute of Scientific and Technical Information of China (English)

    杨培周; 郑志; 罗水忠; 姜绍通; 陈淼林; 高书蕊

    2012-01-01

    The tolerance of Saccharomyces cerevisiae and Pachysolen tannophilus to inhibitors including furfural, 5-hydroxymethyl furfural and levulinic acid in diluted acid hydrolysis from rape straw was investigated. S. cerevisiae was capable of tolerating 2 g/L furfural, 2 g/L 5-hydroxymethyl furfural and 8 g/L levulinic acid in glucose broth. However, ethanol production by P. tannophilus was strongly inhibited in xylose broth added with 2 g/L furfural, 2 g/L 5-hydroxymethyl furfural and 8 g/L levulinic acid, respectively. In glucose broth containing 2 g/L furfural, the ethanol yields of S. cerevisiae and P. tannophilus were respectively 85. 05% and 46. 70% compared with those of the control, while in xylose broth added with 2 g/L furfural, the ethanol yield of P. tannophilus was 12.40% compared with that of the control. Enzymatic hydrolysis of rape straw could effectively relieve the inhibition of 2 g/L furfural on both the S. cerevisiae and P. tannophilus, whose ethanol yields were respectively 98. 40% and 91. 00% compared with those of the control. The results showed that the tolerance capacity of S. cerevisiae on fermentation inhibitors including furfural, 5-hydroxymethyl furfural and levulinic acid was stronger than that of P. tannophilus.%研究了酿酒酵母和嗜鞣管囊酵母对油菜秸秆稀酸水解抑制物糠醛、5-羟甲基糠醛和乙酰丙酸的耐受性.酿酒酵母能够耐受分别含有2 g/L糠醛、2 g/L 5-羟甲基糠醛和8g/L乙酰丙酸的葡萄糖发酵液;分别含有2g/L糠醛、2 g/L 5-羟甲基糠醛和8 g/L乙酰丙酸的木糖发酵液严重抑制嗜鞣管囊酵母发酵木糖产乙醇.在含有2 g/L糠醛的葡萄糖发酵液中,酿酒酵母和嗜鞣管囊酵母的乙醇质量浓度分别为对照的85.05%和46.70%,而在以木糖为底物的发酵液中,嗜鞣管囊酵母的乙醇质量浓度为对照的12.40%.油菜秸秆水解液能够有效缓解2g/L糠醛对酿酒酵母和嗜鞣管囊酵母产乙醇的抑制,乙醇

  13. Stochastic modelling of Listeria monocytogenes single cell growth in cottage cheese with mesophilic lactic acid bacteria from aroma producing cultures.

    Science.gov (United States)

    Østergaard, Nina Bjerre; Christiansen, Lasse Engbo; Dalgaard, Paw

    2015-07-02

    A stochastic model was developed for simultaneous growth of low numbers of Listeria monocytogenes and populations of lactic acid bacteria from the aroma producing cultures applied in cottage cheese. During more than two years, different batches of cottage cheese with aroma culture were analysed for pH, lactic acid concentration and initial concentration of lactic acid bacteria. These data and bootstrap sampling were used to represent product variability in the stochastic model. Lag time data were estimated from observed growth data (lactic acid bacteria) and from literature on L. monocytogenes single cells. These lag time data were expressed as relative lag times and included in growth models. A stochastic model was developed from an existing deterministic growth model including the effect of five environmental factors and inter-bacterial interaction [Østergaard, N.B, Eklöw, A and Dalgaard, P. 2014. Modelling the effect of lactic acid bacteria from starter- and aroma culture on growth of Listeria monocytogenes in cottage cheese. International Journal of Food Microbiology. 188, 15-25]. Growth of L. monocytogenes single cells, using lag time distributions corresponding to three different stress levels, was simulated. The simulated growth was subsequently compared to growth of low concentrations (0.4-1.0 CFU/g) of L. monocytogenes in cottage cheese, exposed to similar stresses, and in general a good agreement was observed. In addition, growth simulations were performed using population relative lag time distributions for L. monocytogenes as reported in literature. Comparably good predictions were obtained as for the simulations performed using lag time data for individual cells of L. monocytogenes. Therefore, when lag time data for individual cells are not available, it was suggested that relative lag time distributions for L. monocytogenes can be used as a qualified default assumption when simulating growth of low concentrations of L. monocytogenes.

  14. PCR of crtNM combined with analytical biochemistry: An efficient way to identify carotenoid producing lactic acid bacteria.

    Science.gov (United States)

    Turpin, Williams; Renaud, Cécile; Avallone, Sylvie; Hammoumi, Aayah; Guyot, Jean-Pierre; Humblot, Christèle

    2016-03-01

    Lactic acid bacteria (LAB) synthesize a wide variety of biochemical compounds during food fermentation. Carotenoids provide important biological functions for bacteria, and their consumption by humans has many beneficial effects. In this study, the presence of several genes involved in the production of carotenoids was determined by BLAST analysis and PCR in a collection of 156 LAB isolated from traditional amylaceous African fermented foods. Only the crtE gene and the crtNM operon were present and detected in Lactobacillaceae. Most of the strains with positive PCR detection of the operon crtNM produced carotenoid-like compounds when grown in MRS broth. The carotenoids produced differed from compounds previously identified in other LAB except for one peak, which was closely related to 4,4'-diaponeurosporene already reported in the literature in Lactobacillus plantarum species. Most producing strains belonged to Lactobacillus fermentum and L. plantarum species but a few Pediococcus acidilactici were also producers. Furthermore, the most efficient L. plantarum was able to synthesize carotenoids in a cereal fermented food. Genetic screening was shown to be efficient since, in all cases, it eliminated the need for biochemical analysis of strains in which no amplicons of the operon crtNM were obtained.

  15. Inhibitory effect of bacteriocin-producing lactic acid bacteria against histamine-forming bacteria isolated from Myeolchi-jeot

    Directory of Open Access Journals (Sweden)

    Eun-Seo Lim

    2016-12-01

    Full Text Available Abstract The objectives of this study were to identify the histamine-forming bacteria and bacteriocin- producing lactic acid bacteria (LAB isolated from Myeolchi-jeot according to sequence analysis of the 16S rRNA gene, to evaluate the inhibitory effects of the bacteriocin on the growth and histamine accumulation of histamine-forming bacteria, and to assess the physico-chemical properties of the bacteriocin. Based on 16S rRNA gene sequences, histamine-forming bacteria were identified as Bacillus licheniformis MCH01, Serratia marcescens MCH02, Staphylococcus xylosus MCH03, Aeromonas hydrophila MCH04, and Morganella morganii MCH05. The five LAB strains identified as Pediococcus acidilactici MCL11, Leuconostoc mesenteroides MCL12, Enterococcus faecium MCL13, Lactobacillus sakei MCL14, and Lactobacillus acidophilus MCL15 were found to produce an antibacterial compound with inhibitory activity against the tested histamine-producing bacteria. The inhibitory activity of these bacteriocins obtained from the five LAB remained stable after incubation at pH 4.0–8.0 and heating for 10 min at 80 °C; however, the bacteriocin activity was destroyed after treatment with papain, pepsin, proteinase K, α-chymotrypsin, or trypsin. Meanwhile, these bacteriocins produced by the tested LAB strains also exhibited histamine-degradation ability. Therefore, these antimicrobial substances may play a role in inhibiting histamine formation in the fermented fish products and preventing seafood-related food-borne disease caused by bacterially generated histamine.

  16. Mass production of spores of lactic acid-producing Rhizopus oryzae NBRC 5384 on agar plate.

    Science.gov (United States)

    Yamane, Tsuneo; Tanaka, Ryosuke

    2013-01-01

    Mass production of sporangiospores (spores) of Rhizopus oryzae NBRC 5384 (identical to NRRL 395 and ATCC 9363) on potato-dextrose-agar medium was studied aiming at starting its L(+)-lactic acid fermentation directly from spore inoculation. Various parameters including harvest time, sowed spore density, size of agar plate, height of air space, and incubation mode of plate (agar-on-bottom or agar-on-top) were studied. Ordinarily used shallow Petri dishes were found out to be unsuitable for the full growth of R. oryzae sporangiophores. In a very wide range of the sowed spore density, the smaller it was, the greater the number of the harvested spores was. It was also interesting to find out that R. oryzae grown downward vertically with a deep air space in an agar-on-top mode gave larger amount of spores than in an agar-on-bottom mode at 30°C for 7-day cultivation. Scale-up of the agar plate culture from 26.4 to 292 cm(2) was studied, resulting in the proportional relationship between the number of the harvested spores/plate and the plate area in the deep Petri dishes. The number of plates of 50 cm in diameter needed for 100 m(3) industrial submerged fermentation started directly from 2 × 10(5) spores/mL inoculum size was estimated as about 6, from which it was inferred that such a fermentation would be feasible. Designing a 50 cm plate and a method of spreading and collecting the spores were suggested. Bioprocess technological significance of the "full-scale industrial submerged fermentation started directly from spore inoculation omitting pre-culture" has been discussed.

  17. Effects of Saccharomyces boulardii on fecal short-chain fatty acids and microflora in patients on long-term total enteral nutrition

    Institute of Scientific and Technical Information of China (English)

    Stéphane M Schneider; Fernand Girard-Pipau; Jér(o)me Filippi; Xavier Hébuterne; Dominique Moyse; Gustavo Calle Hinojosa; Anne Pompei; Patrick Rampal

    2005-01-01

    AIM: To assess the effects of Sb on fecal flora and shortchain fatty acids (SCFA) in patients on long-term TEN.METHODS: Ten patients (3 females, 7 males, 59±5.5 years),on TEN for a median of 13 mo (1-125), and 15 healthy volunteers (4 females, 11 males, 32±2.0 years) received Sb (0.5 g bid PO) for 6 d. Two stool samples were taken before, on the last 2 d and 9-10 d after treatment, for SCFA measurement and for culture and bacterial identification.Values (mean±SE) were compared using sign tests and ANOVA.RESULTS: Fecal butyrate levels were lower in patients(10.1±2.9 mmol/kg) than in controls (19.2±3.9, P= 0.02).Treatment with Sb increased total fecal SCFA levels in patients (150.2±27.2 vs 107.5±18.2 mmol/kg, P = 0.02)but not in controls (129.0±28.6 vs 113.0±15.2 mmol/kg,NS). At the end of treatment with Sb, patients had higher fecal butyrate (16.0±4.4 vs 10.1 [2.9] mmol/kg, P = 0.004).Total SCFAs remained high 9 d after treatment was discontinued. Before the treatment, the anaerobe to aerobe ratio was lower in patients compared to controls (2.4±2.3 vs69.8±1.8, P = 0.003). There were no significant changes in the fecal flora of TEN patients.CONCLUSION: Sb-induced increase of fecal SCFA concentrations (especially butyrate) may explain the preventive effects of this yeast on TEN-induced diarrhea.

  18. Antioxidant activity of pea protein hydrolysates produced by batch fermentation with lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Stanisavljević Nemanja S.

    2015-01-01

    Full Text Available Nine Lactobacillus strains known for surface proteinase activity were chosen from our collection and tested for their ability to grow in pea seed protein-based medium, and to hydrolyze purified pea proteins in order to produce peptides with antioxidant (AO activity. Two strains, Lactobacillus rhamnosus BGT10 and Lactobacillus zeae LMG17315, exhibited strong proteolytic activity against pea proteins. The AO activity of the pea hydrolysate fraction, MW <10 kDa, obtained by the fermentation of purified pea proteins with Lactobacillus rhamnosus BGT10, was tested by standard spectrophotometric assays (DPPH, ABTS, Fe3+-reducing capacity and the recently developed direct current (DC polarographic assay. The low molecular weight fraction of the obtained hydrolysate was separated using ion exchange chromatography, while the AO activity of eluted fractions was determined by means of a sensitive DC polarographic assay without previous concentration of samples. Results revealed that the fraction present in low abundance that contained basic peptides possessed the highest antioxidant activity. Based on the obtained results, it can be concluded that Lactobacillus rhamnosus BGT10 should be further investigated as a candidate strain for large-scale production of bioactive peptides from legume proteins. [Projekat Ministartsva nauke Republike Srbije, br. 173005 i br. 173026

  19. D(—–Lactic Acid Producing Probiotics, D(—–Lactic Acidosis and Infants

    Directory of Open Access Journals (Sweden)

    David R Mack

    2004-01-01

    Full Text Available There is mounting evidence that ingestion of selected probiotics can modify disease morbidity for specific conditions affecting humans, and there is growing interest in the amelioration or prevention of disease with probiotics. Modulation in gene expression of the cellular elements of the intestinal mucosa and interbacterial interactions are leading theories as to the mechanism whereby probiotics can effect benefit for the host. Furthermore, gene-environmental interactions are considered to be important in the development of disease in those at genetic risk. With the intestinal tract harbouring large numbers of bacteria, alteration of the microbial environment with probiotic microbes is being considered as a controllable factor that may limit disease expression for those at genetic risk. This reasoning has led to interest in the administration of probiotics to infants. However, there are significant developmental changes occurring in many organ systems from the time of parturition and during the first months of life. Because there is little in the published scientific medical literature regarding the effects of long-term administration of probiotics to infants, potential problems must be considered; one such issue is that of administration of D(--lactate-producing probiotics. An appraisal of the current knowledge of this potential adverse effect is the subject of this communication.

  20. Microbial quality, physicochemical characteristics and fatty acid composition of a traditional butter produced from cows’ milk in East Algeria

    Directory of Open Access Journals (Sweden)

    Idoui, Tayeb

    2010-09-01

    Full Text Available This is the first report describing microbiological, physicochemical properties and fatty acid composition of a traditional butter produced from cows’ milk in East of Algeria. Five butter samples were prepared in the laboratory according to the traditional method used by people in the Jijel areas (Eastern Algeria. Our results show the presence of lactic acid and psychrotrophic bacteria as well as yeasts, while staphylococci or lipolytic bacteria were not detected. Important differences were found in chemical values among butter samples. The pH values ranged from pH4.64 and pH5.53. Moisture and impurities exceeded 17.5% and 9.19% respectively. The values for acid index, peroxide index, saponification index and iodine index ranged from: 23.56-31.35mg KOH/g, 1.6-4 meq/kg, 140.25- 228.60 mg KOH/g and 35.35-53.69 mgI/100g respectively. Finally, the fatty acid composition showed that palmitic acid and oleic acid were the major saturated and unsaturated fatty acids.

    Esta es la primera vez que se describen las propiedades microbiológicas y fisicoquímicas y la composición en ácidos grasos de una mantequilla tradicional producida con leche de vaca del Este de Argelia. Cinco muestras de mantequilla fueron preparadas en el laboratorio siguiendo el método tradicional usado por la población del área de Jiels (Este de Argelia. Nuestros resultados muestran la presencia de ácido láctico, bacterias psicrotróficas y levaduras, mientras que stafilococos y bacterias lipolíticas no fueron detectadas. Importantes diferencias fueron encontradas en los valores químicos de las diferentes muestras de mantequilla. Los valores de pH variaron entre 4.64 y 5.53. La humedad e impurezas excedió el 17.5% y 9.19%, respectivamente. Los valores de índice de acidez, índice de peróxidos, índice de saponificación e índice de yodo variaron entre: 23.56-31.35 mg KOH/g, 1.6-4 meq/kg, 140.25- 228.60 mg KOH/g and 35.35-53.69 mgI/100g, respectivamente. Finalmente

  1. Complete genome sequence of Enterococcus mundtii QU 25, an efficient L-(+)-lactic acid-producing bacterium.

    Science.gov (United States)

    Shiwa, Yuh; Yanase, Hiroaki; Hirose, Yuu; Satomi, Shohei; Araya-Kojima, Tomoko; Watanabe, Satoru; Zendo, Takeshi; Chibazakura, Taku; Shimizu-Kadota, Mariko; Yoshikawa, Hirofumi; Sonomoto, Kenji

    2014-08-01

    Enterococcus mundtii QU 25, a non-dairy bacterial strain of ovine faecal origin, can ferment both cellobiose and xylose to produce l-lactic acid. The use of this strain is highly desirable for economical l-lactate production from renewable biomass substrates. Genome sequence determination is necessary for the genetic improvement of this strain. We report the complete genome sequence of strain QU 25, primarily determined using Pacific Biosciences sequencing technology. The E. mundtii QU 25 genome comprises a 3 022 186-bp single circular chromosome (GC content, 38.6%) and five circular plasmids: pQY182, pQY082, pQY039, pQY024, and pQY003. In all, 2900 protein-coding sequences, 63 tRNA genes, and 6 rRNA operons were predicted in the QU 25 chromosome. Plasmid pQY024 harbours genes for mundticin production. We found that strain QU 25 produces a bacteriocin, suggesting that mundticin-encoded genes on plasmid pQY024 were functional. For lactic acid fermentation, two gene clusters were identified-one involved in the initial metabolism of xylose and uptake of pentose and the second containing genes for the pentose phosphate pathway and uptake of related sugars. This is the first complete genome sequence of an E. mundtii strain. The data provide insights into lactate production in this bacterium and its evolution among enterococci.

  2. Isolation of bacteriocin - producing lactic acid bacteria from 'Ugba' and 'Okpiye', two locally fermented nigerian food condiments

    Directory of Open Access Journals (Sweden)

    Charles Ogugua Nwuche

    2013-02-01

    Full Text Available In this work, 100 samples each of 'ugba' and 'okpiye' were evaluated for the presence of bacteriocin producing lactic acid bacteria. Thirty strains showing antibacterial activity against at least one of the indicator organisms were selected from a total of 752 colonies isolated from the condiments. Out of the 30, only five strains retained activity after the pH of the broth supernatant was adjusted to 6.5. When evaluated by the agar-well diffusion assay, the spectra of inhibitory activity showed that Staphylococcus aureus was the most sensitive indicator organism tested, while Listeria monocytogenes was the most resistant. One strain (UG 2 was active against Escherichia coli. The assays using the cell-free supernatant of the cultures showed that the bacteriocins were completely inactivated by the proteolyses as well as by the chloroform treatment. In ethanol, the activity of the compounds was only partially modified. When incubated in a water bath at 80°C for 30 min, no significant activity loss was recorded. The antimicrobial activity of the bacteriocins produced by the lactic acid bacteria has potential for use in biopreservation of condiments against the spoilage and food - borne pathogens.

  3. A novel glutamate transport system in poly(γ-glutamic acid)-producing strain Bacillus subtilis CGMCC 0833.

    Science.gov (United States)

    Wu, Qun; Xu, Hong; Zhang, Dan; Ouyang, Pingkai

    2011-08-01

    Bacillus subtilis CGMCC 0833 is a poly(γ-glutamic acid) (γ-PGA)-producing strain. It has the capacity to tolerate high concentration of extracellular glutamate and to utilize glutamate actively. Such a high uptake capacity was owing to an active transport system for glutamate. Therefore, a specific transport system for L-glutamate has been observed in this strain. It was a novel transport process in which glutamate was symported with at least two protons, and an inward-directed sodium gradient had no stimulatory effect on it. K(m) and V(m) for glutamate transport were estimated to be 67 μM and 152 nmol⁻¹ min⁻¹ mg⁻¹ of protein, respectively. The transport system showed structural specificity and stereospecificity and was strongly dependent on extracellular pH. Moreover, it could be stimulated by Mg²⁺, NH₄⁺, and Ca²⁺. In addition, the glutamate transporter in this strain was studied at the molecular level. As there was no important mutation of the transporter protein, it appeared that the differences of glutamate transporter properties between this strain and other B. subtilis strains were not due to the differences of the amino acid sequence and the structure of transporter protein. This is the first extensive report on the properties of glutamate transport system in γ-PGA-producing strain.

  4. Effects of the organic acids produced by a lactic acid bacterium in Apis mellifera colony development, Nosema ceranae control and fumagillin efficiency.

    Science.gov (United States)

    Maggi, Matías; Negri, Pedro; Plischuk, Santiago; Szawarski, Nicolás; De Piano, Fiorella; De Feudis, Leonardo; Eguaras, Martín; Audisio, Carina

    2013-12-27

    The European honey bee Apis mellifera is known to be affected by many parasites and pathogens that have great impact over the insect development. Among parasites affecting bee health, Nosema ceranae is one of the main biotic factors affecting colony populations. As honey bee populations decline, interest in pathogenic and mutualistic relationships between bees and microorganisms has increased. The main goal of the current study was to assess the effect of the oral administration of the metabolites produced by Lactobacillus johnsonii CRL1647 (mainly organic acids) supplemented in syrup, on: (I) N. ceranae sporulation dynamics before and after fumagillin application, and (II) performance of A. mellifera colonies. Different experiments were conducted to evaluate the effects of these bacterial metabolites on bees: in vitro administration revealed no toxic effects against bees. Colonies fed with the lactic acids incremented their beehive population and also the amount of fat bodies per bee. Finally, the organic acids reduced the intensity of the pathogen after the second application of treatment as well as enhanced the fumagillin efficiency. This study provides important information for the development of new control substances against nosemosis.

  5. Comparison of enriched palmitic acid and calcium salts of palm fatty acids distillate fat supplements on milk production and metabolic profiles of high-producing dairy cows.

    Science.gov (United States)

    Rico, D E; Ying, Y; Harvatine, K J

    2014-09-01

    A variable response to fat supplementation has been reported in dairy cows, which may be due to cow production level, environmental conditions, or diet characteristics. In the present experiment, the effect of a high palmitic acid supplement was investigated relative to a conventional Ca salts of palm fatty acids (Ca-FA) supplement in 16 high-producing Holstein cows (46.6±12.4kg of milk/d) arranged in a crossover design with 14-d periods. The experiment was conducted in a non-heat-stress season with 29.5% neutral detergent fiber diets. Treatments were (1) high palmitic acid (PA) supplement fed as free FA [1.9% of dry matter (DM); 84.8% C16:0] and (2) Ca-FA supplement (2.3% of DM; 47.7% C16:0, 35.9% C18:1, and 8.4% C18:2). The PA supplement tended to increase DM intake, and increased the yields of milk and energy-corrected milk. Additionally, PA increased the yields of milk fat, protein, and lactose, whereas milk concentrations of these components were not affected. The yields of milk de novo and 16-C FA were increased by PA compared with Ca-FA (7 and 20%, respectively), whereas the yield of preformed FA was higher in Ca-FA. A reduction in milk fat concentration of de novo and 16-C FA and a marginal elevation in trans-10 C18:1 in Ca-FA is indicative of altered ruminal biohydrogenation and increased risk of milk fat depression. No effect of treatment on plasma insulin was observed. A treatment by time interaction was detected for plasma nonesterified fatty acids (NEFA), which tended to be higher in Ca-FA than in PA before feeding. Overall, the palmitic acid supplement improved production performance in high-producing cows while posing a lower risk for milk fat depression compared with a supplement higher in unsaturated FA.

  6. Chrysotile asbestos detoxification with a combined treatment of oxalic acid and silicates producing amorphous silica and biomaterial.

    Science.gov (United States)

    Valouma, Aikaterini; Verganelaki, Anastasia; Maravelaki-Kalaitzaki, Pagona; Gidarakos, Evangelos

    2016-03-15

    This study was primarily imposed by the ever increasing need for detoxification of asbestos and asbestos containing materials (ACM), with potential application onsite. The present work investigates potential detoxification of pure chrysotile (Chr) asbestos via a combined treatment of oxalic acid dihydrate (Oxac) (Η2C2Ο4·2Η2Ο) with silicates, such as tetraethoxysilane (TEOS) (SiH20C8O4) and pure water glass (WG) (potassium silicate) (K2SiO3). These reagents used in the experimental procedure, do not cause adverse effects on the environment and are cost effective. The results of FTIR, XRD, optical and scanning microscopy coupled with EDS analyses indicated that all of the applied treatments destructed the Chr structure and yielded silica of amorphous phase and the biomaterial glushinskite from the Oxac reacted with brucite [Mg(OH)2] layer. Each of the proposed formulations can be applied for the detoxification of asbestos, according to priorities related to the specific products of the recovery treatment. Therefore, Oxac acid leaching followed by the TEOS addition is preferred in cases of glushinskite recovery; TEOS treatment of asbestos with subsequent Oxac addition produced amorphous silica production; finally Oxac acid leaching followed by WG encapsulated the asbestos fibers and can be used in cases of onsite asbestos and ACM detoxification.

  7. Understanding Longitudinal Wood Fiber Ultra-structure for Producing Cellulose Nanofibrils Using Disk Milling with Diluted Acid Prehydrolysis

    Science.gov (United States)

    Qin, Yanlin; Qiu, Xueqing; Zhu, J. Y.

    2016-10-01

    Here we used dilute oxalic acid to pretreat a kraft bleached Eucalyptus pulp (BEP) fibers to facilitate mechanical fibrillation in producing cellulose nanofibrils using disk milling with substantial mechanical energy savings. We successfully applied a reaction kinetics based combined hydrolysis factor (CHFX) as a severity factor to quantitatively control xylan dissolution and BEP fibril deploymerization. More importantly, we were able to accurately predict the degree of polymerization (DP) of disk-milled fibrils using CHFX and milling time or milling energy consumption. Experimentally determined ratio of fibril DP and number mean fibril height (diameter d), DP/d, an aspect ratio measurer, were independent of the processing conditions. Therefore, we hypothesize that cellulose have a longitudinal hierarchical structure as in the lateral direction. Acid hydrolysis and milling did not substantially cut the “natural” chain length of cellulose fibrils. This cellulose longitudinal hierarchical model provides support for using weak acid hydrolysis in the production of cellulose nanofibrils with substantially reduced energy input without negatively affecting fibril mechanical strength.

  8. Engineered production of fungal anticancer cyclooligomer depsipeptides in Saccharomyces cerevisiae.

    Science.gov (United States)

    Yu, Dayu; Xu, Fuchao; Zi, Jiachen; Wang, Siyuan; Gage, David; Zeng, Jia; Zhan, Jixun

    2013-07-01

    Two fungal cyclooligomer depsipeptide synthetases(CODSs), BbBEAS (352 kDa) and BbBSLS (348 kDa) from Beauveria bassiana ATCC7159, were reconstituted in Saccharomyces cerevisiae BJ5464-NpgA, leading to the production of the corresponding anticancer natural products, beauvericins and bassianolide, respectively. The titers of beauvericins (33.8 ± 1.4 mg/l) and bassianolide (21.7± 0.1 mg/l) in the engineered S. cerevisiae BJ5464-NpgA strains were comparable to those in the native producer B. bassiana. Feeding D-hydroxyisovaleric acid (D-Hiv) and the corresponding L-amino acid precursors improved the production of beauvericins and bassianolide. However, the high price of D-Hiv limits its application in large-scale production of these cyclooligomer depsipeptides. Alternatively, we engineered another enzyme, ketoisovalerate reductase (KIVR) from B. bassiana, into S. cerevisiae BJ5464-NpgA for enhanced in situ synthesis of this expensive substrate. Co-expression of BbBEAS and KIVR in the yeast led to significant improvement of the production of beauvericins.The total titer of beauvericin and its congeners (beauvericins A-C) was increased to 61.7 ± 3.0 mg/l and reached 2.6-fold of that in the native producer B. bassiana ATCC7159. Supplement of L-Val at 10 mM improved the supply of ketoisovalerate, the substrate of KIVR, which consequently further increased the total titer of beauvericins to 105.8 ± 2.1 mg/l. Using this yeast system,we functionally characterized an unknown CODS from Fusarium venenatum NRRL 26139 as a beauvericin synthetase, which was named as FvBEAS. Our work thus provides a useful approach for functional reconstitution and engineering of fungal CODSs for efficient production of this family of anticancer molecules.

  9. Kinetic modeling, production and characterization of an acidic lipase produced by Enterococcus durans NCIM5427 from fish waste.

    Science.gov (United States)

    Ramakrishnan, Vrinda; Goveas, Louella Concepta; Halami, Prakash M; Narayan, Bhaskar

    2015-03-01

    Enterococcus durans NCIM5427 (ED-27), capable of producing an intracellular acid stable lipase, was isolated from fish processing waste. Its growth and subsequent lipase production was optimized by Box Behneken design (optimized conditions: 5 % v/v fish waste oil (FWO), 0.10 mg/ml fish waste protein hydrolysates (FWPH) at 48 h of fermentation time). Under optimized conditions, ED-27 showed a 3.0 fold increase (207.6 U/ml to 612.53 U/ml) in lipase production, as compared to un-optimized conditions. Cell growth and lipase production was modeled using Logistic and Luedeking-Piret model, respectively; and lipase production by ED-27 was found to be growth-associated. Lipase produced by ED-27 showed stability at low pH ranges from 2 to 5 with its optimal activity at 30 °C , pH 4.6; showed metal ion dependent activity wherein its catalytic activity was activated by barium, sodium, lithium and potassium (10 mM); reduced by calcium and magnesium (10 mM). However, iron and mercury (5 mM) completely inactivated the enzyme. In addition, modifying agents like SDS, DTT, β-ME (1%v/v) increased activity of lipase of ED-27; while, PMSF, DEPC and ascorbic acid resulted in a marked decrease. ED-27 had maximum cell growth of 9.90309 log CFU/ml under optimized conditions as compared to 13 log CFU/ml in MRS. The lipase produced has potential application in poultry and slaughterhouse waste management.

  10. Kinetics of Asymmetric Reduction of Phenylglyoxylic Acid to R-(-)-Mandelic Acid by Saccharomyces Cerevisiae FD11b%酵母细胞FD11b生物不对称公式(R)-(-)-扁桃酸的动力学研究

    Institute of Scientific and Technical Information of China (English)

    肖美添; 黄雅燕; 孟春; 郭养浩

    2006-01-01

    The kinetics of asymmetric production of R-(-)-mandelic acid (R-MA) from phenylglyoxylic acid (PGA)catalyzed by Saccharomyces cerevisiae sp. strain FD11b was studied by fed-batch cultures. The concentrations of glucose and PGA were controlled respectively with a dual feeding system. When the electron donor glucose was supplied at the rate of 0.0833mmol·gdw-1·h-1, the specific production rate (qp) and the enantiomeric excess of R-MAreached the maximum 0.353mmol·gdw-1·h-1 and 97.1%, respectively. The apparent reduction activity of yeast FD11b was obviously affected by both substrate PGA and product MA. The qp value reached the maximum 0.36-0.38mmol·gdw-1·h-1 when the PGA concentration was controlled between 25 and 35mmol·L-1. The obvious substrate inhibition of bioconversion was observed at the PGA concentrations higher than 40mmol· L-1. The accumulation of product MA also caused a severe feed-back inhibition for its production when the product concentration was above 60mmol· L-1. The kinetic model with the inhibition effect of both substrate and product was simulated by a computer-based least-square arithmatic. The established kinetic model was in good agreement with the experimental data.

  11. Isolation, identification and characterization of regional indigenous Saccharomyces cerevisiae strains

    Science.gov (United States)

    Šuranská, Hana; Vránová, Dana; Omelková, Jiřina

    2016-01-01

    In the present work we isolated and identified various indigenous Saccharomyces cerevisiae strains and screened them for the selected oenological properties. These S. cerevisiae strains were isolated from berries and spontaneously fermented musts. The grape berries (Sauvignon blanc and Pinot noir) were grown under the integrated and organic mode of farming in the South Moravia (Czech Republic) wine region. Modern genotyping techniques such as PCR-fingerprinting and interdelta PCR typing were employed to differentiate among indigenous S. cerevisiae strains. This combination of the methods provides a rapid and relatively simple approach for identification of yeast of S. cerevisiae at strain level. In total, 120 isolates were identified and grouped by molecular approaches and 45 of the representative strains were tested for selected important oenological properties including ethanol, sulfur dioxide and osmotic stress tolerance, intensity of flocculation and desirable enzymatic activities. Their ability to produce and utilize acetic/malic acid was examined as well; in addition, H2S production as an undesirable property was screened. The oenological characteristics of indigenous isolates were compared to a commercially available S. cerevisiae BS6 strain, which is commonly used as the starter culture. Finally, some indigenous strains coming from organically treated grape berries were chosen for their promising oenological properties and these strains will be used as the starter culture, because application of a selected indigenous S. cerevisiae strain can enhance the regional character of the wines. PMID:26887243

  12. Interaction among Btn1p, Btn2p, and Ist2p reveals potential interplay among the vacuole, amino acid levels, and ion homeostasis in the yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Kim, Yoojin; Chattopadhyay, Subrata; Locke, Sarahjane; Pearce, David A

    2005-02-01

    Btn2p, a novel cytosolic coiled-coil protein in Saccharomyces cerevisiae, was previously shown to interact with and to be necessary for the correct localization of Rhb1p, a regulator of arginine uptake, and Yif1p, a Golgi protein. We now report the biochemical and physical interactions of Btn2p with Ist2p, a plasma membrane protein that is thought to have a function in salt tolerance. A deletion in Btn2p (btn2Delta strains) results in a failure to correctly localize Ist2p, and strains lacking Btn2p and Ist2p (btn2Delta ist2Delta strains) are unable to grow in the presence of 0.5 or 1.0 M NaCl. Btn2p was originally identified as being up-regulated in a btn1Delta strain, which lacks the vacuolar-lysosomal membrane protein, Btn1p, and serves as a model for Batten disease. This up-regulation of Btn2p was shown to contribute to the maintenance of a stable vacuolar pH in the btn1Delta strain. Btn1p was subsequently shown to be required for the optimal transport of arginine into the vacuole. Interestingly, btn1Delta ist2Delta strains are also unable to grow in the presence of 0.5 or 1.0 M NaCl, and ist2Delta suppresses the vacuolar arginine transport defect in btn1Delta strains. Although further investigation is required, we speculate that altered vacuolar arginine transport in btn1Delta strains represents a mechanism for maintaining or balancing cellular ion homeostasis. Btn2p interacts with at least three proteins that are seemingly involved in different biological functions in different subcellular locations. Due to these multiple interactions, we conclude that Btn2p may play a regulatory role across the cell in response to alterations in the intracellular environment that may be caused by changes in amino acid levels or pH, a disruption in protein trafficking, or imbalances in ion homeostasis resulting from either genetic or environmental manipulation.

  13. Screening for new brewing yeasts in the non-Saccharomyces sector with Torulaspora delbrueckii as model.

    Science.gov (United States)

    Michel, Maximilian; Kopecká, Jana; Meier-Dörnberg, Tim; Zarnkow, Martin; Jacob, Fritz; Hutzler, Mathias

    2016-04-01

    This study describes a screening system for future brewing yeasts focusing on non-Saccharomyces yeasts. The aim was to find new yeast strains that can ferment beer wort into a respectable beer. Ten Torulaspora delbrueckii strains were put through the screening system, which included sugar utilization tests, hop resistance tests, ethanol resistance tests, polymerase chain reaction fingerprinting, propagation tests, amino acid catabolism and anabolism, phenolic off-flavour tests and trial fermentations. Trial fermentations were analysed for extract reduction, pH drop, yeast concentration in bulk fluid and fermentation by-products. All investigated strains were able to partly ferment wort sugars and showed high tolerance to hop compounds and ethanol. One of the investigated yeast strains fermented all the wort sugars and produced a respectable fruity flavour and a beer of average ethanol content with a high volatile flavour compound concentration. Two other strains could possibly be used for pre-fermentation as a bio-flavouring agent for beers that have been post-fermented by Saccharomyces strains as a consequence of their low sugar utilization but good flavour-forming properties.

  14. Recombinant Production of Human Aquaporin-1 to an Exceptional High Membrane Density in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Bomholt, Julie; Helix Nielsen, Claus; Scharff-Poulsen, Peter

    2013-01-01

    In the present paper we explored the capacity of yeast Saccharomyces cerevisiae as host for heterologous expression of human Aquaporin-1. Aquaporin-1 cDNA was expressed from a galactose inducible promoter situated on a plasmid with an adjustable copy number. Human Aquaporin-1 was C-terminally tag......In the present paper we explored the capacity of yeast Saccharomyces cerevisiae as host for heterologous expression of human Aquaporin-1. Aquaporin-1 cDNA was expressed from a galactose inducible promoter situated on a plasmid with an adjustable copy number. Human Aquaporin-1 was C...... at 15°C in a yeast host over-producing the Gal4p transcriptional activator and growth in amino acid supplemented minimal medium. In-gel fluorescence combined with western blotting showed that low accumulation of correctly folded recombinant Aquaporin-1 at 30°C was due to in vivo mal-folding. Reduction...... of the expression temperature to 15°C almost completely prevented Aquaporin-1 mal-folding. Bioimaging of live yeast cells revealed that recombinant Aquaporin-1 accumulated in the yeast plasma membrane. A detergent screen for solubilization revealed that CYMAL-5 was superior in solubilizing recombinant Aquaporin-1...

  15. Stimulation of butyrate production by gluconic acid in batch culture of pig cecal digesta and identification of butyrate-producing bacteria.

    Science.gov (United States)

    Tsukahara, Takamitsu; Koyama, Hironari; Okada, Masaaki; Ushida, Kazunari

    2002-08-01

    Gluconic acid reaches the large intestine to stimulate lactic acid bacteria. However, the fermentation pattern of gluconic acid has yet to be elucidated. Accordingly, we examined the fermentation properties induced by gluconic acid in the pig cecal digesta in vitro. We also tested sorbitol and glucose, substrates for which the fermentation rate and patterns are known. The gluconic acid-utilizing bacteria were further isolated from pig cecal digesta and identified to examine the effect of gluconic acid on hind gut fermentation. Gluconic acid was fermented more slowly than were the other two substrates. Gluconic acid stimulated butyrate production; the butyrate molar percentage reached 26%, which is considered a high butyrate production. The majority of gluconic acid fermenters were identified as lactic acid bacteria, such as Lactobacillus reuteri and L. mucosae, and acid-utilizing bacteria, such as Megasphaera elsdenii and Mitsuokella multiacida. The gluconic acid fermented by lactic acid bacteria, and the lactate and acetate that were produced were used to form butyrate by acid-utilizing bacteria, such as M. elsdenii. Gluconic acid may be useful as a prebiotic to stimulate butyrate production in the large intestine.

  16. Evolutionary systems biology of amino acid biosynthetic cost in yeast.

    Directory of Open Access Journals (Sweden)

    Michael D Barton

    Full Text Available Every protein has a biosynthetic cost to the cell based on the synthesis of its constituent amino acids. In order to optimise growth and reproduction, natural selection is expected, where possible, to favour the use of proteins whose constituents are cheaper to produce, as reduced biosynthetic cost may confer a fitness advantage to the organism. Quantifying the cost of amino acid biosynthesis presents challenges, since energetic requirements may change across different cellular and environmental conditions. We developed a systems biology approach to estimate the cost of amino acid synthesis based on genome-scale metabolic models and investigated the effects of the cost of amino acid synthesis on Saccharomyces cerevisiae gene expression and protein evolution. First, we used our two new and six previously reported measures of amino acid cost in conjunction with codon usage bias, tRNA gene number and atomic composition to identify which of these factors best predict transcript and protein levels. Second, we compared amino acid cost with rates of amino acid substitution across four species in the genus Saccharomyces. Regardless of which cost measure is used, amino acid biosynthetic cost is weakly associated with transcript and protein levels. In contrast, we find that biosynthetic cost and amino acid substitution rates show a negative correlation, but for only a subset of cost measures. In the economy of the yeast cell, we find that the cost of amino acid synthesis plays a limited role in shaping transcript and protein expression levels compared to that of translational optimisation. Biosynthetic cost does, however, appear to affect rates of amino acid evolution in Saccharomyces, suggesting that expensive amino acids may only be used when they have specific structural or functional roles in protein sequences. However, as there appears to be no single currency to compute the cost of amino acid synthesis across all cellular and environmental

  17. Transfer RNA pseudouridine synthases in Saccharomyces cerevisiae.

    Science.gov (United States)

    Samuelsson, T; Olsson, M

    1990-05-25

    A transfer RNA lacking modified nucleosides was produced by transcription in vitro of a cloned gene that encodes a Saccharomyces cerevisiae glycine tRNA. At least three different uridines (in nucleotide positions 13, 32, and 55) of this transcript tRNA are modified to pseudouridine by an extract of S. cerevisiae. Variants of the RNA substrate were also constructed that each had only one of these sites, thus allowing specific monitoring of pseudouridylation at different nucleotide positions. Using such RNAs to assay pseudouridine synthesis, enzymes producing this nucleoside were purified from an extract of S. cerevisiae. The activities corresponding to positions 13, 32, and 55 in the tRNA substrate could all be separated chromatographically, indicating that there is a separate enzyme for each of these sites. The enzyme specific for position 55 (denoted pseudouridine synthase 55) was purified approximately 4000-fold using a combination of DEAE-Sepharose, heparin-Sepharose, and hydroxylapatite.

  18. In vitro evaluation of bacteriocin-like inhibitory substances produced by lactic acid bacteria isolated during traditional Sicilian cheese making

    Directory of Open Access Journals (Sweden)

    Giusi Macaluso

    2016-02-01

    Full Text Available Bacteriocins are antimicrobial proteins produced by bacteria that inhibit the growth of other bacteria with a bactericidal or bacteriostatic mode of action. Many lactic acid bacteria (LAB produce a high diversity of different bacteriocins. Bacteriocinogenic LAB are generally recognised as safe (GRAS and useful to control the frequent development of pathogens and spoilage microorganisms. For this reason they are commonly used as starter cultures in food fermentations. In this study, the authors describe the results of a screening on 699 LAB isolated from wooden vat surfaces, raw milk and traditional Sicilian cheeses, for the production of bacteriocin-like inhibitory substances, by comparing two alternative methods. The antagonistic activity of LAB and its proteinaceous nature were evaluated using the spot-on-the-lawn and the well-diffusion assay (WDA and the sensitivity to proteolytic (proteinase K, protease B and trypsin, amylolytic (α-amylase and lipolytic (lipase enzymes. The indicator strains used were: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Salmonella enteritidis. A total of 223 strains (belonging to the species Enterococcus spp., Lactobacillus spp., Pediococcus spp., Streptococcus spp., Leuconostoc spp. and Lactococcus lactis were found to inhibit the growth of Listeria monocytogenes by using the spot-on-the-lawn method; only 37 of these were confirmed by using the WDA. The direct addition of bacteriocin-producing cultures into dairy products can be a more practical and economic option for the improvement of the safety and quality of the final product.

  19. The role of resistance to bile salts and acid tolerance of exopolysaccharides (EPSS produced by yogurt starter bacteria

    Directory of Open Access Journals (Sweden)

    Boke Hatice

    2010-01-01

    Full Text Available The aim of this study was to investigate a possible relation between EPS production and resistance to bile salts and tolerance to low pH. Eight strains which produced the highest and lowest amount of EPS (16- 211mg/l were selected among 54 bacteria isolated from yogurt. Additionally, they were tested for resistance to bile salts (0.15, 0.3 % and tolerance to low pH (2.0-3.0. After treatment with bile salts and acid, viable bacteria (log cfu ml-1 were determined by surface plating. The high EPS producing strains (B3, G12, W22 showed a significant (P<0.05 protective effect against low pH (pH 2.0. All Streptococcus thermophilus strains showed a higher tolerance to bile salts than the Lactobacillus delbrueckii subsp. bulgaricus strains. The high EPS-producing S. thermophilus (W22, T12 and L. bulgaricus (B3, G2 strains showed a significant (P<0.01 protective effect against bile salts (0.3 %.

  20. Multiplex PCR method for the simultaneous detection of histamine-, tyramine-, and putrescine-producing lactic acid bacteria in foods.

    Science.gov (United States)

    Marcobal, Angela; de las Rivas, Blanca; Moreno-Arribas, M Victoria; Muñoz, Rosario

    2005-04-01

    In a screening of primers, we have selected three pairs of primers for a multiplex PCR assay for the simultaneous detection of lactic acid bacteria (LAB) strains, which potentially produce histamine, tyramine, and putrescine on fermented foods. These primers were based on sequences from histidine, tyrosine, and ornithine decarboxylases from LAB. Under the optimized conditions, the assay yielded a 367-bp DNA fragment from histidine decarboxylases, a 924-bp fragment from tyrosine decarboxylases, and a 1,446-bp fragment from ornithine decarboxylases. When the DNAs of several target organisms were included in the same reaction, two or three corresponding amplicons of different sizes were observed. This assay was useful for the detection of amine-producing bacteria in control collection strains and in a LAB collection. No amplification was observed with DNA from nonproducing LAB strains. This article is the first describing a multiplex PCR approach for the simultaneous detection of potentially amine-producing LAB in foods. It can be easily incorporated into the routine screening for the accurate selection of starter LAB and in food control laboratories.

  1. In Vitro Evaluation of Bacteriocin-Like Inhibitory Substances Produced by Lactic Acid Bacteria Isolated During Traditional Sicilian Cheese Making

    Science.gov (United States)

    Macaluso, Giusi; Fiorenza, Gerlando; Gaglio, Raimondo; Mancuso, Isabella

    2016-01-01

    Bacteriocins are antimicrobial proteins produced by bacteria that inhibit the growth of other bacteria with a bactericidal or bacteriostatic mode of action. Many lactic acid bacteria (LAB) produce a high diversity of different bacteriocins. Bacteriocinogenic LAB are generally recognised as safe (GRAS) and useful to control the frequent development of pathogens and spoilage microorganisms. For this reason they are commonly used as starter cultures in food fermentations. In this study, the authors describe the results of a screening on 699 LAB isolated from wooden vat surfaces, raw milk and traditional Sicilian cheeses, for the production of bacteriocin-like inhibitory substances, by comparing two alternative methods. The antagonistic activity of LAB and its proteinaceous nature were evaluated using the spot-on-the-lawn and the well-diffusion assay (WDA) and the sensitivity to proteolytic (proteinase K, protease B and trypsin), amylolytic (a-amylase) and lipolytic (lipase) enzymes. The indicator strains used were: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Salmonella enteritidis. A total of 223 strains (belonging to the species Enterococcus spp., Lactobacillus spp., Pediococcus spp., Streptococcus spp., Leuconostoc spp. and Lactococcus lactis) were found to inhibit the growth of Listeria monocytogenes by using the spot-on-the-lawn method; only 37 of these were confirmed by using the WDA. The direct addition of bacteriocin-producing cultures into dairy products can be a more practical and economic option for the improvement of the safety and quality of the final product.

  2. Characterization of low-acetic-acid-producing yeast isolated from 2-deoxyglucose-resistant mutants and its application to high-gravity brewing.

    Science.gov (United States)

    Mizuno, Akihiro; Tabei, Hideaki; Iwahuti, Masahumi

    2006-01-01

    We isolated a mutant with low acetic acid and high ethanol productivities from 2-deoxyglucose-resistant mutants of brewers' yeast NCYC1245 (Saccharomyces cerevisiae). To determine the mechanism for these properties in the mutant (2DGR19) during fermentation, gene expression and enzyme activity related to acetic acid and ethanol production were investigated. DNA microarray analysis revealed that the transcriptional levels of many genes involved in glycolysis were higher in 2DGR19 than in NCYC1245. Among these transcriptional levels of 2DGR19 relative to NCYC1245, the expression level of ADH4 encoding alcohol dehydrogenase (ADH) was highest, which corresponded to the high ADH activity in 2DGR19. Quantitative PCR analysis also revealed that the transcriptional level of ADH4 was the highest among ADH1 to ADH4. Although no significant differences in the transcriptional levels of ALD2 to ALD6 encoding acetaldehyde dehydrogenase (ALD) between 2DGR19 and NCYC1245 were observed, ALD activity in 2DGR19 was lower. Using quantitative PCR analysis, ALD6 was found to be the most highly expressed among the ALD2 to ALD6 genes. These results indicate that ALD6 contributes to a low ALD activity, depending on post-transcriptional regulation. A high ADH activity appeared to be the major reason for the high ethanol productivity of 2DGR19. A low ALD activity was considered to be principally responsible for a low acetic acid productivity, although a high ADH activity also might have played a role. Beer brewed using 2DGR19 in pilot-scale high-gravity brewing contained about half as much acetic acid and 1.1% more ethanol compared with that brewed using NCYC1245. The use of 2DGR19 may overcome difficulties associated with high-gravity brewing.

  3. Prebiotic content of bread prepared with flour from immature wheat grain and selected dextran-producing lactic acid bacteria.

    Science.gov (United States)

    Pepe, Olimpia; Ventorino, Valeria; Cavella, Silvana; Fagnano, Massimo; Brugno, Rachele

    2013-06-01

    In the last few years the need to produce food with added value has fueled the search for new ingredients and health-promoting compounds. In particular, to improve the quality of bakery products with distinct nutritional properties, the identification of new raw materials, appropriate technologies, and specific microbial strains is necessary. In this study, different doughs were prepared, with 10% and 20% flour from immature wheat grain blended with type "0 America" wheat flour. Immature flour was obtained from durum wheat grains harvested 1 to 2 weeks after anthesis. Doughs were obtained by both the straight-dough and sourdough processes. Two selected exopolysaccharide-producing strains of lactic acid bacteria (LAB), Leuconostoc lactis A95 and Lactobacillus curvatus 69B2, were used as starters. Immature flour contained 2.21 g/100 g (dry weight) of fructo-oligosaccharides. Twenty percent immature flour in dough resulted in a shorter leavening time (4.23 ± 0.03 h) than with the control and dough with 10% immature flour. The total titratable acidity of sourdough with 20% immature flour was higher (12.75 ± 0.15 ml 0.1 N NaOH) than in the control and sourdough with 10% immature wheat flour (9.20 ml 0.1 N NaOH). Molecular analysis showed that all samples contained three LAB species identified as L. lactis, L. curvatus, and Pediococcus acidilactici. A larger amount of exopolysaccharide was found in sourdough obtained with 20% immature flour (5.33 ± 0.032 g/kg), positively influencing the exopolysaccharide content of the bread prepared by the sourdough process (1.70 ± 0.03 g/kg). The addition of 20% immature flour also led to a greater presence of fructo-oligosaccharides in the bread (900 mg/100 g dry weight), which improved its nutritional characteristics. While bread volume decreased as the concentration of immature wheat flour increased, its mechanical characteristics (stress at a strain of 30%) were the same in all samples obtained with different percentages of

  4. Quantitative analysis of fatty-acid-based biofuels produced by wild-type and genetically engineered cyanobacteria by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Guan, Wenna; Zhao, Hui; Lu, Xuefeng; Wang, Cong; Yang, Menglong; Bai, Fali

    2011-11-11

    Simple and rapid quantitative determination of fatty-acid-based biofuels is greatly important for the study of genetic engineering progress for biofuels production by microalgae. Ideal biofuels produced from biological systems should be chemically similar to petroleum, like fatty-acid-based molecules including free fatty acids, fatty acid methyl esters, fatty acid ethyl esters, fatty alcohols and fatty alkanes. This study founded a gas chromatography-mass spectrometry (GC-MS) method for simultaneous quantification of seven free fatty acids, nine fatty acid methyl esters, five fatty acid ethyl esters, five fatty alcohols and three fatty alkanes produced by wild-type Synechocystis PCC 6803 and its genetically engineered strain. Data obtained from GC-MS analyses were quantified using internal standard peak area comparisons. The linearity, limit of detection (LOD) and precision (RSD) of the method were evaluated. The results demonstrated that fatty-acid-based biofuels can be directly determined by GC-MS without derivation. Therefore, rapid and reliable quantitative analysis of fatty-acid-based biofuels produced by wild-type and genetically engineered cyanobacteria can be achieved using the GC-MS method founded in this work.

  5. Ixr1p and the control of the Saccharomyces cerevisiae hypoxic response.

    Science.gov (United States)

    Vizoso-Vázquez, Angel; Lamas-Maceiras, Mónica; Becerra, Manuel; González-Siso, M Isabel; Rodríguez-Belmonte, Esther; Cerdán, M Esperanza

    2012-04-01

    In Saccharomyces cerevisiae, adaptation to hypoxia/anaerobiosis requires the transcriptional induction or derepression of multiple genes organized in regulons controlled by specific transcriptional regulators. Ixr1p is a transcriptional regulatory factor that causes aerobic repression of several hypoxic genes (COX5B, TIR1, and HEM13) and also the activation of HEM13 during hypoxic growth. Analysis of the transcriptome of the wild-type strain BY4741 and its isogenic derivative Δixr1, grown in aerobic and hypoxic conditions, reveals differential regulation of genes related not only to the hypoxic and oxidative stress responses but also to the re-adaptation of catabolic and anabolic fluxes in response to oxygen limitation. The function of Ixr1p in the transcriptional regulation of genes from the sulfate assimilation pathway and other pathways producing α-keto acids is of biotechnological importance for industries based on yeast-derived fermentation products.

  6. Growth and fermentation characteristics of Saccharomyces cerevisiae NK28 isolated from kiwi fruit.

    Science.gov (United States)

    Lee, Jong-Sub; Park, Eun-Hee; Kim, Jung-Wan; Yeo, Soo-Hwan; Kim, Myoung-Dong

    2013-09-28

    The influences of glucose concentration, initial medium acidity (pH), and temperature on the growth and ethanol production of Saccharomyces cerevisiae NK28, which was isolated from kiwi fruit, were examined in shake flask cultures. The optimal glucose concentration, initial medium pH, and temperature for ethanol production were 200 g/l, pH 6.0, and 35oC, respectively. Under this growth condition, S. cerevisiae NK28 produced 98.9 ± 5.67 g/l ethanol in 24 h with a volumetric ethanol production rate of 4.12 ± 0.24 g/l·h. S. cerevisiae NK28 was more tolerant to heat and ethanol than laboratory strain S. cerevisiae BY4742, and its tolerance to ethanol and fermentation inhibitors was comparable to that of an ethanologen, S. cerevisiae D5A.

  7. Selection of Indigenous Saccharomyces cerevisiae Strains from Kutjevo Wine Growing Area at the Laboratoy Scale

    Directory of Open Access Journals (Sweden)

    Sandi Orlić

    2005-09-01

    Full Text Available The use of selected yeasts for winemaking has clear advantages over traditional spontaneous fermentation. Selection of wine yeasts is usually carried out within the Saccharomyces cerevisiae species. Yeast strains produce different amount of secondary compounds that impart specific characteristics to the wines. This suggests that it is necessary to isolate naturally occuring autochthone strains, which exhibit a metabolic profile that corresponds to each wine. Twenty two strains of S.cerevisiae, isolated from the Kutjevo region (Gornji and Donji Hrnjevec, Mitrovac, Graševina grapes, were tested for: fermentation vigor, ethanol resistance, volatile acidity, H2S production and β-glucosidase, polygalacturonase, and killer activity. From the results of this investigation we are able to select two yeast strains (RO 1272 and RO 1284 for more detailed fermentation trials and possible use as a starter culture in production of typical wines.

  8. Specific fragments of phi X174 deoxyribonucleic acid produced by a restriction enzyme from Haemophilus aegyptius, endonuclease Z.

    Science.gov (United States)

    Middleton, J H; Edgell, M H; Hutchison, C A

    1972-07-01

    A restriction-like enzyme has been purified from Haemophilus aegyptius. This nuclease, endonuclease Z, produces a rapid decrease in the viscosity of native calf thymus and H. influenzae deoxyribonucleic acids (DNA), but does not degrade homologous DNA. The specificity of endonuclease Z is different from that of the similar endonuclease isolated from H. influenzae (endonuclease R). The purified enzyme cleaves the double-stranded replicative form DNA of bacteriophage phiX174 (phiX174 RF DNA) into at least 11 specific limit fragments whose molecular sizes have been estimated by gel electrophoresis. The position of these fragments with respect to the genetic map of phiX174 can be determined by using the genetic assay for small fragments of phiX174 DNA.

  9. Plasmonic-based colorimetric and spectroscopic discrimination of acetic and butyric acids produced by different types of Escherichia coli through the different assembly structures formation of gold nanoparticles.

    Science.gov (United States)

    La, Ju A; Lim, Sora; Park, Hyo Jeong; Heo, Min-Ji; Sang, Byoung-In; Oh, Min-Kyu; Cho, Eun Chul

    2016-08-24

    We present a plasmonic-based strategy for the colourimetric and spectroscopic differentiation of various organic acids produced by bacteria. The strategy is based on our discovery that particular concentrations of dl-lactic, acetic, and butyric acids induce different assembly structures, colours, and optical spectra of gold nanoparticles. We selected wild-type (K-12 W3110) and genetically-engineered (JHL61) Escherichia coli (E. coli) that are known to primarily produce acetic and butyric acid, respectively. Different assembly structures and optical properties of gold nanoparticles were observed when different organic acids, obtained after the removal of acid-producing bacteria, were mixed with gold nanoparticles. Moreover, at moderate cell concentrations of K-12 W3110 E. coli, which produce sufficient amounts of acetic acid to induce the assembly of gold nanoparticles, a direct estimate of the number of bacteria was possible based on time-course colour change observations of gold nanoparticle aqueous suspensions. The plasmonic-based colourimetric and spectroscopic methods described here may enable onsite testing for the identification of organic acids produced by bacteria and the estimation of bacterial numbers, which have applications in health an