Search results for: S. cerevisiae

Authors: Neil Jolly, Louisa Beukes, Santiago Benito-SaEz

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Kei-apple is a tree found on the African continent. Limited information exists on the effect of alcoholic and acetous fermentation on the phytochemicals. The fruit has increased L-malic, ascorbic, and phenolic acids. Juice was co-inoculated with Schizosaccharomyces pombe and Saccharomyces cerevisiae to induce alcoholic fermentation and acetous fermentation using acetic acid bacteria. Saccharomyces cerevisiae+S. pombe wines and vinegars had highest pH. Total acidity, soluble solids and L-malic acid decreased during alcoholic and acetous fermentation with highest in S. cerevisiae wines and vinegars. Volatile acidity was highest in S. pombe vinegars but not different from S. cerevisiae and S. cerevisiae+S. pombe. Gallic acid was highest in S. pombe wines and vinegars. Syringic acid was highest in S. cerevisiae wines and vinegars. S. cerevisiae+S. pombe wines were highest in caffeic, p-coumaric and protocatechuic acids. Schizosaccharomyces pombe vinegars were highest in caffeic and p-coumaric acids. Ferulic and sinapic acids were highest in S. pombe and S. cerevisiae wines, respectively. Chlorogenic acid was most abundant in both wines and vinegars. Saccharomyces cerevisiae+S. pombe and S. cerevisiae had a positive effect on most phenolic acids. Saccharomyces cerevisiae +acetic acid bacteria had an increased effect on syringic and chlorogenic acids. Schizosaccharomyces pombe+acetic acid bacteria resulted in an increase in gallic, caffeic and p-coumaric acids. Acetic acid bacteria had minimal performance with respect to volatile acidity production in comparison to commercial vinegars. Acetic acid bacteria selection should therefore be reconsidered and the decrease of certain phenolic acids during acetous fermentation needs to be investigated.

Keywords: acetic acid bacteria, liquid chromatography, phenolics, saccharomyces cerevisiae, schizosaccharomyces pombe

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Authors: Thi Huong Vu, Haelee Fenton, Thi Huong Tra Nguyen, Gary Dykes

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In the present study, a submerged fermentation of carob kibble with Saccharomyces cerevisiae (S. cerevisiae) was performed. The total phenolic content and antioxidant activity in fermented carob kibble were determined by Folin–Ciocalteu method and scavenging capacity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS). The study showed that S. cerevisiae improved total phenolic content by 45 % and 50 % in acetone and water extracts respectively. Similarly, the antioxidant capacity of water extracts increased by 25 % and 41%, while acetone extracts indicated by 70% and 80% in DPPH and ABTS respectively. It is also found that initial pH 7.0 was more effective in improvement of total phenolic content and antioxidant activity. The efficiency of treatment was recorded at 15 h. This report suggested that submerged fermentation with S. cerevisiae is a potential and cost effective manner to further increase bioactive compounds in carob kibble, which are in use for food, cosmetic and pharmaceutical industries.

Keywords: antioxidant activity, carob kibble, saccharomyces cerevisiae, submerged fermentation, total phenolics

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Authors: Thi Huong Vu, Vijay Jayasena, Zhongxiang Fang, Gary Dykes

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Carob kibble has recently received attention due to the presence of high level of polyphenol antioxidants. The capacity of microorganisms to improve antioxidant activities and total phenolics in carob kibble was investigated in the study. Two types of microorganisms including lactic acid bacteria Lactobacillus plantarum (L. plantarum) and yeast Saccharomyces cerevisiae (S. cerevisiae) were used in single and in their combination as starters. The total phenolic content was determined by the Folin–Ciocalteu method. Antioxidant activities were assessed scavenging capacity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS). The study found that S. cerevisiae alone considerably improved 55% total phenolics content at 15 h, while L. plantarum caused in a loss of 20% through the process. Antioxidant capacity of the yeast-fermented samples significantly increased by 43 % and 10 % in ABTS and DPPH assays, respectively. However, reduction of 13 % and 32 % inhibition were recorded in the carob treated with L. plantarum. In the combination of S. cerevisiae and L. plantarum (1:1), both total phenolic content and antioxidant activity of carob kibble were a similar trend as these of S. cerevisiae single, but a lower improvement. The antioxidant power of the extracts was linearly correlated to their total phenolic contents (R=0.75). The results suggested that S. cerevisiae alone was the better for enhancement of both total phenolic content and antioxidant activity in carob kibble using submerged fermentation. The efficiency of fermentation reached the highest at 15h. Thus submerged fermentation with S. cerevisiae offers a tool with simple and cost effective to further increase the bioactive potential of carob kibble, which is in use for food, cosmetic and pharmaceutical industries.

Keywords: antioxidant activity, carob kibble, lactobacillus plantarum, saccharomyces cerevisiae, total phenolics

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Authors: Mardiati Zain, Jurnida Rahman, Khasrad, Erpomen

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The aim of this experiment was to study the use of palm oil by products (oil palm fronds (OPF), palm oil sludge (POS) and palm kernel cake (PKC)), that supplemented with growth factor rumen microbes (Sapindus rarak and Sacharomyces cerevisiae) on digestibility and fermentation in vitro. Oil Palm Fronds was previously treated with 3% urea. The treatments consist of 50% OPF+ 30% POS+ 20% PKC as a control diet (A), B = A + 4% Sapindus rarak, C = A + 0.5 % Sacharomyces cerevisiae and D = A + 4% Sapindus rarak + 0.5% Sacharomyces cerevisiae. Digestibility of DM, OM, ADF, NDF, cellulose and rumen parameters (NH3 and VFA) of all treatments were significantly different (P < 0.05). Fermentation and digestibility treatment A were significantly lower than treatments B, C, and D. The result indicated that supplementation Sapindus rarak and S. cerevisiae were able to improve fermentability and digestibility of palm oil by product.

Keywords: palm oil by product, Sapindus rarak, Sacharomyces rerevisiae, fermentability, OPF ammoniated

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Authors: M. A. Zeinelabdeen, A. E. Abasaeed, M. H. Gaily, A. K. Sulieman, M. D. Putra

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The effect of temperature on the production of fructose and bioethanol from date syrup via selective fermentation by S. cerevisiae ATCC 36859 strain was studied. Various temperatures have been tested (27, 30 and 33 ᵒC). The fermentation experiments were conducted in a water shaker bath at the three temperatures under testing and 120 rpm. The results showed that a high fructose yield can be achieved at all temperatures under testing while the optimal is 27 ᵒC with 84% fructose yield. A high ethanol yield can be obtained for all temperatures under testing. However; the maximum biomass concentration and ethanol yield (86.22%) were obtained at 30 ᵒC.

Keywords: dates, ethanol, fructose, fermentation, S. cerevisiae

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Authors: Yina A. Cifuentes Triana, Andrés M. Pinzón Velásco, Marío E. Velásquez Lozano

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In this work the sequencing and genome characterization of a natural isolate of Saccharomyces cerevisiae yeast (strain 202-3), identified with potential for the production of second generation ethanol from sugarcane bagasse hydrolysates is presented. This strain was selected because its capability to consume xylose during the fermentation of sugarcane bagasse hydrolysates, taking into account that many strains of S. cerevisiae are incapable of processing this sugar. This advantage and other prominent positive aspects during fermentation profiles evaluated in bagasse hydrolysates made the strain 202-3 a candidate strain to improve the production of second-generation ethanol, which was proposed as a first step to study the strain at the genomic level. The molecular characterization was carried out by genome sequencing with the Illumina HiSeq 2000 platform paired end; the assembly was performed with different programs, finally choosing the assembler ABYSS with kmer 89. Gene prediction was developed with the approach of hidden Markov models with Augustus. The genes identified were scored based on similarity with public databases of nucleotide and protein. Records were organized from ontological functions at different hierarchical levels, which identified central metabolic functions and roles of the S. cerevisiae strain 202-3, highlighting the presence of four possible new proteins, two of them probably associated with the positive consumption of xylose.

Keywords: cellulosic ethanol, Saccharomyces cerevisiae, genome sequencing, xylose consumption

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Authors: Thi Huong Vu, Vijay Jayasena, Zhongxiang Fang, Gary Dykes

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D-pinitol (3-O-methyl ether of D-chiro-inosito) has been known to have health benefits for diabetic patients. Carob kibble has received attention due to the presence of high value D-pinitol and polyphenol antioxidants. D-pinitol was concentrated from carob kibble using submerged fermentation with Saccharomyces cerevisiae. Total carbohydrates and D-pinitol were determined by the phenol-sulphuric acid method and HPLC, respectively. The content of D-pinitol increased from approximately 43 to 70 mg/g dry weight after fermentation. The yeast consumed over 70% of total carbohydrates in carob kibble without any negative effect on D-pinitol content. A range of substrate medium pH’s from 5.0 – 7.0 had no significant effect on the removal of carbohydrates and D-pinitol. This method may provide a practical solution for production of D-pinitol from carob in a cost effective manner.

Keywords: carob kibble, d-pinitol, saccharomyces cerevisiae, submerged fermentation, total carbohydrates

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Authors: Noor Akhmazillah Fauzi, Mohammed Mehdi Farid, Filipa V. Silva

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The aim of this paper is to investigate if different concentration of Manuka honey (as a model food) has a major influence on the inactivation of Saccharomyces cerevisiae (as the testing microorganism) after subjecting it to HPP. Honey samples with different sugar concentrations (20, 30, 40, 50, 60 and 70 °Brix) were prepared aseptically using sterilized distilled water. No dilution of honey was made for the 80 °Brix sample. For the 0 °Brix sample (control), sterilized distilled water was used. Thermal treatment at 55 °C for 10 min (conventionally applied in honey pasteurisation in industry) was carried out for comparison purpose. S. cerevisiae cell numbers in honey samples were established before and after each HPP and thermal treatment. The number of surviving cells was determined after a proper dilution of the untreated and treated samples by the viable plate count method. S. cerevisiae cells, in different honey concentrations (0 to 80 °Brix), subjected to 600 MPa (at ambient temperature) showed an increasing resistance to inactivation with °Brix. A significant correlation (p < 0.05) between cell reduction and °Brix was found. Cell reduction in high pressure-treated samples varied linearly with °Brix (R2 > 0.9), confirming that the baroprotective effect of the food is due to sugar content. This study has practical implications in establishing efficient process design for commercial manufacturing of high sugar food products and on the potential use of HPP for such products.

Keywords: high pressure processing, honey, Saccharomyces cerevisiae, °Brix

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Authors: Sajjad ur Rahman, Mariam Azam, Mukarram Bashir, Seemal Javaid, Aoun Muhammad, Muhammad Tahir, Jawad, Hannan Khan, Muhammad Zohaib

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Partially fermented soya hulls and wheat bran through Saccharomyces cerevisiae (DL-22 S/N) substantiated as a natural source for quality milk production. Saccharomyces cerevisiae (DL-22 S/N) were grown under in-vivo conditions and processed through two-step fermentation with substrates. The extra pure metabolites (XPM) were dried and processed for maintaining 1mm mesh size particles for supplementation of pelleted feed. Two groups of a cow (Holstein Friesian) having 8 animals of similar age and lactation were given the experimental concentrates. Group A was fed daily with 12gm of XPM and 22% protein-pelleted feed, while Group B was provided with no metabolites in their feed. In thirty-nine days of trial, improvement in the overall health, body score, milk protein, milk fat, ash, and solid not fat (SNF), yield, and incidence rate of mastitis was observed. The collected data revealed an improvement in milk production of 2.02 liter/h/d. However, a reduction (3.75%) in the milk fats and an increase in the milk SNF was around 0.58%. The ash content ranged between 6.4-7.5%. The incidence of mastitis was reduced to less than 2%.

Keywords: microbial metabolites, Saccharomyces cerevisiae, milk production, fermentation, post-biotic metabolites, immunity

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Authors: E. Soboleva, E. Sergachyova, S. G. Davydenko, T. V. Meledina

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Problem of food preservation is extremely important for mankind. Viscous damage ("illness") of bread results from development of Bacillus spp. bacteria. High temperature resistant spores of this microorganism are steady against 120°C) and remain in bread during pastries, potentially causing spoilage of the final product. Scientists are interested in further characterization of bread spoiling Bacillus spp. species. Our aim was to find weather yeast Saccharomyces cerevisiae strains that are able to produce natural antimicrobial killer factor can preserve bread illness. By diffusion method, we showed yeast antagonistic activity against spore-forming bacteria. Experimental technological parameters were the same as for bakers' yeasts production on the industrial scale. Risograph test during dough fermentation demonstrated gas production. The major finding of the study was a clear indication of the presence of killer yeast strain antagonistic activity against rope in bread causing bacteria. After demonstrating antagonistic effect of S. cerevisiae on bacteria using solid nutrient medium, we tested baked bread under provocative conditions. We also measured formation of carbon dioxide in the dough, dough-making duration and quality of the final products, when using different strains of S. cerevisiae. It is determined that the use of yeast S. cerevisiae RCAM 01730 killer strain inhibits appearance of rope in bread. Thus, natural yeast antimicrobial killer toxin, produced by some S. cerevisiae strains is an anti-rope in bread protector.

Keywords: bakers' yeasts, killer toxin, rope in bread, Saccharomyces cerevisiæ

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Authors: Farnaz Yusuf, Naseem A. Gaur

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The increase in environmental concerns, rapid depletion of fossil fuel reserves and intense interest in achieving energy security has led to a global research effort towards developing renewable sources of fuels. Second generation biofuels have attracted more attention recently as the use of lignocellulosic biomass can reduce fossil fuel dependence and is environment-friendly. Xylose is the main pentose and second most abundant sugar after glucose in lignocelluloses. Saccharomyces cerevisiae does not readily uptake and use pentose sugars. For an economically feasible biofuel production, both hexose and pentose sugars must be fermented to ethanol. Therefore, it is important to develop S. cerevisiae host platforms with more efficient xylose utilization. This work aims to construct a xylose fermenting yeast strains with engineered oxido-reductative pathway for xylose metabolism. Engineered strain was further improved by adaptive evolutionary engineering approach. The engineered strain is able to grow on xylose as sole carbon source with the maximum ethanol yield of 0.39g/g xylose and productivity of 0.139g/l/h at 96 hours. The further improvement in strain development involves over expression of pentose phosphate pathway and protein engineering of xylose reductase/xylitol dehydrogenase to change their cofactor specificity in order to reduce xylitol accumulation.

Keywords: biofuel, lignocellulosic biomass, saccharomyces cerevisiae, xylose

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Authors: Valiollah Babaeipour, Mahdi Rahaie

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food supplements are rich in specific nutrients and bioactive compounds that eliminate free radicals and improve cellular metabolism. The major bioactive compounds are found in bran and cereal sprouts. Secondary metabolites of these microorganisms have antioxidant properties that can be used alone or in combination with chemotherapy and radiation therapy to treat cancer. Biologically active compounds such as benzoquinone derivatives extracted from fermented wheat germ extract (FWGE) have several positive effects on the overall state of human health and strengthen the immune system. The present work describes the discontinuous fermentation of raw wheat germ for FWGE production through the simultaneous culture process using the probiotic strains of Saccharomyces cerevisiae, Lactobacillus plantarum, and the possibility of using solid waste. To increase production efficiency, first to select important factors in the optimization of each fermentation process, using a factorial statistical scheme of stirring fraction (120 to 200 rpm), dilution of solids to solvent (1 to 8-12), fermentation time (16 to 24 hours) and strain to wheat germ ratio (20% to 50%) were studied and then simultaneous culture was performed to increase the yields of 2 and 6 dimethoxybenzoquinone (2,6-DMBQ). Since 2 and 6 dimethoxy benzoquinone were fermented as the main biologically active compound in wheat germ extract, UV-Vis analysis was performed to confirm the presence of 2 and 6 dimethoxy benzoquinone in the final product. In addition, 2,6-DMBQ of some products was isolated in a non-polar C-18 column and quantified using high performance liquid chromatography (HPLC). Based on our findings, it can be concluded that the increase of 2 and 6 dimethoxybenzoquinone in the simultaneous culture of Saccharomyces cerevisiae - Lactobacillus plantarum compared to pure culture of Saccharomyces cerevisiae (from 1.89 mg / g) to 28.9% (2.66 mg / g) Increased.

Keywords: wheat germ, FWGE, saccharomyces cerevisiae, lactobacillus plantarum, co-culture, 2, 6-DMBQ

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Authors: B. Santoso, B. Tj. Hariadi, H. Abubakar

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The aim of the experiment was to evaluate the effect of probiotic addition in concentrate on fermentation characteristics and in vitro nutrient digestibility of the grass Pennisetum purpureophoides. Two strains lactic acid bacteria (LAB) i.e Lactobacillus plantarum and Lactobacillus acidhophilus, and one strain yeast of Saccharomyces cerevisiae were used as probiotic. The probiotics was added at 2% and 4% (v/w) in the concentrate. The result showed the concentrate containing between 1.5 × 106 and 3 × 107 CFU/g of lactic acid bacteria and 3 × 103 CFU/g of S. cerevisiae. The DM, OM and NDF digestibility were higher (P<0.01) in grass substrate with concentrate than in grass alone. Addition of probiotic in concentrate increased (P<0.01) DM, OM and NDF compared to concentrate without probiotic. Total VFA and propionic acid concentrations were higher (P<0.01) in grass substrate with concentrate than in grass alone. Concentration of acetic acid decreased (P<0.01) in grass substrate with concentrate than in grass substrate alone. Addition of L. plantarum and L. acidophilus and S. cerevisiae in concentrate increased (P<0.01) propionic acid concentration. It was concluded that addition of probiotic in concentrate increased propionic concentration and in vitro nutrient digestibility.

Keywords: by-products, concentrate, digestibility, probiotics

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Authors: Madhalasa Iyer

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The increase in sustainable practices have encouraged the research and production of alternative fuels. New techniques of bio flocculation with the addition of yeast and bacteria strains have increased the efficiency of biofuel production. Fatty acid methyl ester (FAME) analysis in previous research has indicated that yeast can serve as a plausible enhancer for microalgal lipid production. The research hopes to identify the yeast and microalgae treatment group that produces the largest algae biomass. The mass of the dried algae is used as a proxy for TAG production correlating to the cultivation of biofuels. The study uses a model bioreactor created and built using PVC pipes, 8-port sprinkler system manifold, CO2 aquarium tank, and disposable water bottles to grow the microalgae. Nannochloropsis sp., and Isochrysis galbanawere inoculated separately in experimental group 1 and 2 with no treatments and in experimental groups 3 and 4 with each algaeco-cultured with Saccharomyces cerevisiae in the medium of standard garden stone fertilizer. S. cerevisiae was grown in a petri dish with nutrient agar medium before inoculation. A Secchi stick was used before extraction to collect data for the optical density of the microalgae. The biomass estimator was then used to measure the approximate production of biomass. The microalgae were grown and extracted with a french press to analyze secondary measurements using the dried biomass. The experimental units of Isochrysis galbana treated with the baker’s yeast strains showed an increase in the overall mass of the dried algae. S. cerevisiae proved to be an accurate and helpful addition to the solution to provide for the growth of algae. The increase in productivity of this fuel source legitimizes the possible replacement of non-renewable sources with more promising renewable alternatives. This research furthers the notion that yeast and mutants can be engineered to be employed in efficient biofuel creation.

Keywords: biofuel, co-culture, S. cerevisiae, microalgae, yeast

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Authors: Zain Ul Abadeen, Muhammad Zargham Khan, Muhammad Kashif Saleemi, Ahrar Khan, Ijaz Javed Hassan, Aisha Khatoon, Qasim Altaf

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Aflatoxins are secondary metabolites produced by toxigenic fungi, and there are four types of aflatoxins include AFB1, AFB2, AFG1 and AFG2. Aflatoxin B1 (AFB1) is considered as most toxic form. It is mainly responsible for the contamination of poultry feed and produces a condition called aflatoxicosis leads to immunosuppression in poultry birds. Saccharomyces cerevisiae is a single cell microorganism and acts as a source of growth factors, minerals and amino acids which improve the immunity and digestibility in poultry birds as probiotics. Saccharomyces cerevisiae is well recognized to cause the biological degradation of mycotoxins (toxin binder) because its cell wall contains β-glucans and mannans which specifically bind with aflatoxins and reduce their absorption or transfer them to some non-toxic compounds. The present study was designed to investigate the immunosuppressive effects of aflatoxins in broiler chicks and the reduction of severity of these effects by the use of Baker’s Yeast (Saccharomyces cerevisiae). One-day-old broiler chicks were procured from local hatchery and were divided into various groups (A-I). These groups were treated with different levels of AFB1 @ 400 µg/kg and 600 µg/kg along with different levels of Baker’s Yeast (Saccharomyces cerevisiae) 0.1% and 0.5 % in the feed. The total duration of the experiment was six weeks and different immunological parameters including the cellular immune response by injecting PHA-P (Phytohemagglutinin-P) in the skin of the birds, phagocytic function of mononuclear cells by Carbon clearance assay from blood samples and humoral immune response against intravenously injected sheep RBCs from the serum samples were determined. The birds from each group were slaughtered at the end of the experiment to determine the presence of gross lesions in the immune organs and these tissues were fixed in 10% neutral buffered formalin for histological investigations. The results showed that AFB1 intoxicated groups had reduced body weight gain, feed intake, organs weight and immunological responses compared to the control and Baker’s Yeast (Saccharomyces cerevisiae) treated groups. Different gross and histological degenerative changes were recorded in the immune organs of AFB1 intoxicated groups compared to control and Baker’s Yeast (Saccharomyces cerevisiae) treated groups. The present study concluded that Baker’s Yeast (Saccharomyces cerevisiae) addition in the feed helps to ameliorate the immunotoxigenic effects produced by AFB1 in broiler chicks.

Keywords: aflatoxins, body weight gain, feed intake, immunological response, toxigenic effect

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Authors: Z. Herceg, V. Stulic, T. Vukusic, A. Rezek Jambrak

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Gas phase plasma treatment is a new nonthermal technology used for food and water decontamination. In this study, we have investigated influence of the gas phase plasma treatment on yeast cells of S. cerevisiae. Sample was composed of 10 mL of yeast suspension and 190 mL of 0.01 M NaNO₃ with a medium conductivity of 100 µS/cm. Samples were treated in a glass reactor with a point- to-plate electrode configuration (high voltage electrode-titanium wire in the gas phase and grounded electrode in the liquid phase). Air or argon were injected into the headspace of the reactor at the gas flow of 5 L/min. Frequency of 60, 90 and 120 Hz, time of 5 and 10 min and positive polarity were defined parameters. Inactivation was higher with the applied higher frequency, longer treatment time and injected argon. Inactivation was not complete which resulted in complete recovery. Cellular leakage (260 nm and 280 nm) was higher with a longer treatment time and higher frequency. Leakage at 280 nm which defines a leakage of proteins was higher than leakage at 260 nm which defines a leakage of nucleic acids. The authors would like to acknowledge the support by Croatian Science Foundation and research project 'Application of electrical discharge plasma for preservation of liquid foods'.

Keywords: Saccharomyces cerevisiae, inactivation, gas-phase plasma treatment, cellular leakage

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Authors: Patrícia Branco, Catarina Prista, Helena Albergaria

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Industrial fuel-ethanol fermentations are carried out under non-sterile conditions, which favors the development of microbial contaminants, leading to huge economic losses. Wild yeasts such as Brettanomyces bruxellensis and lactic acid bacteria are the main contaminants of industrial bioethanol fermentation, affecting Saccharomyces cerevisiae performance and decreasing ethanol yields and productivity. In order to control microbial contaminations, the fuel-ethanol industry uses different treatments, including acid washing and antibiotics. However, these control measures carry environmental risks such as acid toxicity and the rise of antibiotic-resistant bacteria. Therefore, it is crucial to develop and apply less toxic and more environmentally friendly biocontrol methods. In the present study, an industrial fuel-ethanol starter, S. cerevisiae Ethanol-Red, was genetically modified to over-express AMPs with activity against fuel-ethanol microbial contaminants and evaluated regarding its biocontrol effect during mixed-culture alcoholic fermentations artificially contaminated with B. bruxellensis. To achieve this goal, S. cerevisiae Ethanol-Red strain was transformed with a plasmid containing the AMPs-codifying genes, i.e., partial sequences of TDH1 (925-963 bp) and TDH2/3 (925-963 bp) and a geneticin resistance marker. The biocontrol effect of those genetically modified strains was evaluated against B. bruxellensis and compared with the antagonistic effect exerted by the modified strain with an empty plasmid (without the AMPs-codifying genes) and the non-modified strain S. cerevisiae Ethanol-Red. For that purpose, mixed-culture alcoholic fermentations were performed in a synthetic must use the modified S. cerevisiae Ethanol-Red strains together with B. bruxellensis. Single-culture fermentations of B. bruxellensis strains were also performed as a negative control of the antagonistic effect exerted by S. cerevisiae strains. Results clearly showed an improved biocontrol effect of the genetically-modified strains against B. bruxellensis when compared with the modified Ethanol-Red strain with the empty plasmid (without the AMPs-codifying genes) and with the non-modified Ethanol-Red strain. In mixed-culture fermentation with the modified S. cerevisiae strain, B. bruxellensis culturability decreased from 5×104 CFU/mL on day-0 to less than 1 CFU/mL on day-10, while in single-culture B. bruxellensis increased its culturability from 6×104 to 1×106 CFU/mL in the first 6 days and kept this value until day-10. Besides, the modified Ethanol-Red strain exhibited an enhanced antagonistic effect against B. bruxellensis when compared with that induced by the non-modified Ethanol-Red strain. Indeed, culturability loss of B. bruxellensis after 10 days of fermentation with the modified Ethanol-Red strain was 98.7 and 100% higher than that occurred in fermentations performed with the non-modified Ethanol-Red and the empty-plasmid modified strain, respectively. Therefore, one can conclude that the S. cerevisiae genetically modified strain obtained in the present work may be a valuable solution for the mitigation of microbial contamination in fuel-ethanol fermentations, representing a much safer and environmentally friendly preservation strategy than the antimicrobial treatments (acid washing and antibiotics) currently applied in fuel-ethanol industry.

Keywords: antimicrobial peptides, fuel-ethanol microbial contaminations, fuel-ethanol fermentation, biocontrol agents, genetically-modified yeasts

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Authors: Abdol-Hassan Doulah

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In this study, antimicrobial activity of essential oil and ethyl acetate and ether extracts of S. nemorosa were examined against some species of bacteria and fungi. The essential oil of the aerial part of S. nemorosa was examined by GC and GC-MS. In the essential oil of S. nemorosa 26 Compounds have been identified. 2-Nonanone (44.09 %), 2-Undecanone (33.79 %), E-Caryophyllene (3.74 %) and 2-Decanone (2.89 %) were the main components of the essential oil. The essential oil analysis showed greatest antimicrobial activity against Staphylococcus epidermidis (5.3 μg/ml) and S. cerevisiae (9.3 μg/ml). The ethyl acetate showed greatest antimicrobial activity against Bacillus subtilis (106.7 μg/ml), Candida albicans (5.3 μg/ml) and ether extract showed greatest antimicrobial activity against Klebseilla pneumoniae (10.7 μg/ml) and Saccharomyces cerevisiae (10.7 μg/ml). In conclusion, we suggest that the antimicrobial activity of S. nemorosa may be due to its content of germacrene and linalool.

Keywords: antibacterial activity, antifungal activity, Salvia nemorosa L., essential oils, biological activity

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Authors: Adeyemi Isaac Sanusi, Gueguim E. B. Kana

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Nanoparticles have received attention of the scientific community due to their biotechnological potentials. They exhibit advantageous size, shape and concentration-dependent catalytic, stabilizing, immunoassays and immobilization properties. This study investigates the impact of metallic oxide nanoparticles (NPs) on ethanol production by Saccharomyces cerevisiae BY4743. Nine different nanoparticles were synthesized using precipitation method and microwave treatment. The nanoparticles synthesized were characterized by Fourier Transform Infra-Red spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fermentation processes were carried out at varied NPs concentrations (0 – 0.08 wt%). Highest ethanol concentrations were achieved after 24 h using Cobalt NPs (5.07 g/l), Copper NPs (4.86 g/l) and Manganese NPs (4.74 g/l) at 0.01 wt% NPs concentrations, which represent 13%, 8.7% and 5.4% increase respectively over the control (4.47 g/l). The lowest ethanol concentration (0.17 g/l) was obtained when 0.08 wt% of Silver NPs was used. And lower ethanol concentrations were observed at higher NPs concentration. Ethanol concentration decrease after 24 h for all the processes. In all set up with NPs, the pH was observed to be stable and the stability was directly proportional to nanoparticles concentrations. These findings suggest that the presence of some of the NPs in the bioprocesses has catalytic and pH stabilizing potential. Ethanol production by Saccharomyces cerevisiae BY4743 was enhanced in the presence of Cobalt NPs, Copper NPs and Manganese NPs. Optimization study using response surface methodology (RSM) will further elucidate the impact of these nanoparticles on bioethanol production.

Keywords: agitation, bioethanol, nanoparticles concentration, optimization, pH value

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Authors: C. Nobre, C. C. Castro, A.-L. Hantson, J. A. Teixeira, L. R. Rodrigues, G. De Weireld

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Fructo-oligosaccharides (FOS) are produced from sucrose by Aureobasidium pullulans in yields between 40-60% (w/w). To increase the amount of FOS it is necessary to remove the small, non-prebiotic sugars, present. Two methods for producing high-purity FOS have been developed: the use of microorganisms able to consume small saccharides; and the use of continuous chromatography to separate sugars: simulated moving bed (SMB). It is herein proposed the combination of both methods. The aim of this study is to optimize the composition of the fermentative broth (in terms of salts and sugars) that will be further purified by SMB. A yield of 0.63 gFOS.g Sucrose-1 was obtained with A. pullulans using low amounts of salts in the initial fermentative broth. By removing the small sugars, Saccharomyces cerevisiae and Zymomonas mobilis increased the percentage of FOS from around 56.0% to 83% (w/w) in average, losing only 10% (w/w) of FOS during the recovery process.

Keywords: fructo-oligosaccharides, microbial treatment, Saccharomyces cerevisiae, Zymomonas mobilis

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Authors: Jesus Alfredo Ortega Granados, Pandiyan Thangarasu

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Antibiotic tetracycline presents as a micro-contaminant in fresh water, wastewater and soils, causing environmental and health problems. In this work, tetracycline (TC) has been employed as chemo-sensor for the recognition of Al³⁺ without interring other ions, and the results show that it enhances the fluorescence intensity for Al³⁺ and there is no interference from other coexisting cation ions (Cd²⁺, Ni²⁺, Co²⁺, Sr²⁺, Mg²⁺, Fe³⁺, K⁺, Sm³⁺, Ag⁺, Na⁺, Ba²⁺, Zn²⁺, and Mn²⁺). For the addition of Cu²⁺ to [TET-Al³⁺], it appears that the intensity of fluorescence has been quenched. Other combinations of metal ions in addition to TC do not change the fluorescence behavior. The stoichiometry determined by Job´s plot for the interaction of TC with Al³⁺ was found to be 1:1. Importantly, the detection of Al³⁺⁺ successfully employed in the real samples like living cells, and it was found that TC efficiently performs as a fluorescent probe for Al³⁺ ion in living systems, especially in Saccharomyces cerevisiae; this is confirmed by confocal laser scanning microscopy.

Keywords: chemo-sensor, recognition of Al³⁺ ion, Saccharomyces cerevisiae, tetracycline,

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Authors: Angela U. Makolo, Temitayo A. Olagunju

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The knowledge of signaling pathways is central to understanding the biological mechanisms of organisms since it has been identified that in eukaryotic organisms, the number of signaling pathways determines the number of ways the organism will react to external stimuli. Signaling pathways are studied using protein interaction networks constructed from protein-protein interaction data obtained using high throughput experimental procedures. However, these high throughput methods are known to produce very high rates of false positive and negative interactions. In order to construct a useful protein interaction network from this noisy data, computational methods are applied to validate the protein-protein interactions. In this study, a computational technique to identify signaling pathways from a protein interaction network constructed using validated protein-protein interaction data was designed. A weighted interaction graph of the Saccharomyces cerevisiae (Baker’s Yeast) organism using the proteins as the nodes and interactions between them as edges was constructed. The weights were obtained using Bayesian probabilistic network to estimate the posterior probability of interaction between two proteins given the gene expression measurement as biological evidence. Only interactions above a threshold were accepted for the network model. A pathway was formalized as a simple path in the interaction network from a starting protein and an ending protein of interest. We were able to identify some pathway segments, one of which is a segment of the pathway that signals the start of the process of meiosis in S. cerevisiae.

Keywords: Bayesian networks, protein interaction networks, Saccharomyces cerevisiae, signalling pathways

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Authors: Nurcan Cetinkaya, Nadide Hulya Ozdemir

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The aim of the study was to investigate the effect of Saccharomyces cerevisiae (SC) live yeast culture on microbial protein supply to the small intestine in Kivircik male yearlings when fed with different ratio of forage and concentrate diets. Four Kivircik male yearlings with permanent rumen canula were used in the experiment. . The treatments were allocated to a 4x4 Latin square design. Diet I consisted of 70% alfalfa hay and 30% concentrate, Diet II consisted of 30% alfalfa hay and 70% concentrate, Diet I and II were supplemented with a SC. Daily urine was collected and stored at -20°C until analysis. Calorimetric methods were used for the determination of urinary allantoin and creatinin levels. The estimated microbial N supply to small intestine for Diets I, I+SC, II and II+SC were 2.51, 2.64, 2.95 and 3.43 g N/d respectively. Supplementation of Diets I and II with SC significantly affected the allantoin levels in µmol/W0. 75 (p<0.05). Mean creatinine values in µmol/W0. 75 and allantoin:creatinin ratios were not significantly different among diets. In conclusion, supplementation with SC live yeast culture had a significant effect on urinary allantoin excretion and microbial protein supply to small intestine in Kivircik yearlings fed with high concentrate Diet II (P<0.05). Hence urinary allantoin excretion may be used as a tool for estimating microbial protein supply in Kivircık yearlings. However, further studies are necessary to understand the metabolism of Saccharomyces cerevisiae live yeast culture with different forage: concentrate ratio in Kıvırcık Yearlings.

Keywords: allantoin, creatinin, Kivircik yearling, microbial nitrogen, Saccharomyces cerevisia

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Authors: Jessy Mattar, Mohamad Turk, Maurice Nonus, Nikolai Lebovka, Henri El Zakhem, Eugene Vorobiev

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The effects of electro-stimulation of S. cerevisiae cells in colloidal suspension by Pulsed Electric Fields ‎‎(PEF) with electric field strength E = 20 – 2000 V.cm-1 and effective PEF treatment time tPEF = 10^−5 – 1 s were ‎investigated. The applied experimental procedure includes variations in the preliminary fermentation time and ‎electro-stimulation by PEF-treatment. Plate counting was performed.‎ At relatively high electric fields (E ≥ 1000 V.cm-1) and moderate PEF treatment time (tPEF > 100 µs), the ‎extraction of ionic components from yeast was observed by conductivity measurements, which can be related to ‎electroporation of cell membranes. Cell counting revealed a dependency of the colonies’ size on the time of ‎preliminary fermentation tf and the power consumption W, however no dependencies were noticeable by varying the initial yeast concentration in the treated suspensions.‎

Keywords: intensification, yeast, fermentation, electroporation, biotechnology

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Authors: Juliana Lukša, Bazilė Ravoitytė, Elena Servienė, Saulius Serva

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Totiviridae L-A virus is a persistent Saccharomyces cerevisiae dsRNA virus. It encodes the major structural capsid protein Gag and Gag-Pol fusion protein, responsible for virus replication and encapsulation. These features also enable the copying of satellite dsRNAs (called M dsRNAs) encoding a secreted toxin and immunity to it (known as killer toxin). Viral capsid pore presumably functions in nucleotide uptake and viral mRNA release. During cell division, sporogenesis, and cell fusion, the virions remain intracellular and are transferred to daughter cells. By employing high throughput RNA sequencing data analysis, we describe the influence of solely L-A virus on the expression of genes in three different S. cerevisiae hosts. We provide a new perception into Totiviridae L-A virus-related transcriptional regulation, encompassing multiple bioinformatics analyses. Transcriptional responses to L-A infection were similar to those induced upon stress or availability of nutrients. It also delves into the connection between the cell metabolism and L-A virus-conferred demands to the host transcriptome by uncovering host proteins that may be associated with intact virions. To better understand the virus-host interaction, we applied differential proteomic analysis of virus particle-enriched fractions of yeast strains that harboreither complete killer system (L-A-lus and M-2 virus), M-2 depleted orvirus-free. Our analysis resulted in the identification of host proteins, associated with structural proteins of the virus (Gag and Gag-Pol). This research was funded by the European Social Fund under the No.09.3.3-LMT-K-712-19-0157“Development of Competences of Scientists, other Researchers, and Students through Practical Research Activities” measure.

Keywords: totiviridae, killer virus, proteomics, transcriptomics

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Authors: Vishwesh Kulkarni, Nikhil Bellarykar

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Cellular complexity stems from the interactions among thousands of different molecular species. Thanks to the emerging fields of systems and synthetic biology, scientists are beginning to unravel these regulatory, signaling, and metabolic interactions and to understand their coordinated action. Reverse engineering of biological networks has has several benefits but a poor quality of data combined with the difficulty in reproducing it limits the applicability of these methods. A few years back, many of the commonly used predictive algorithms were tested on a network constructed in the yeast Saccharomyces cerevisiae (S. cerevisiae) to resolve this issue. The network was a synthetic network of five genes regulating each other for the so-called in vivo reverse-engineering and modeling assessment (IRMA). The network was constructed in S. cereviase since it is a simple and well characterized organism. The synthetic network included a variety of regulatory interactions, thus capturing the behaviour of larger eukaryotic gene networks on a smaller scale. We derive a new set of algorithms by solving a nonlinear optimization problem and show how these algorithms outperform other algorithms on these datasets.

Keywords: synthetic gene network, network identification, optimization, nonlinear modeling

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Authors: Darin Khumsupan, Tidarat Komolwanich, Sirirat Prasertwasu, Thanyalak Chaisuwan, Apanee Luengnaruemitchai, Sujitra Wongkasemjit

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Bioethanol production has become a subject of interest for many researchers due to its potential to replace fossil fuels. Since the most popular sources of bioethanol originate from food crops including corn and sugarcane, many people become more concerned with increasing demand for food supply. Lignocellulosic biomass, such as grass, could be a practical alternative to replace the conventional fossil fuels due to its low cost, renewability, and abundance in nature. Mission grass (Pennisetum polystachion) is one of the candidates for bioethanol production. This research is focused on the detoxification and fermentation of hydrolysate from mission grass. Glucose in the hydrolysate was detoxified by overliming process at various pH. Although overliming at pH 12 gave the highest yeast population, the ethanol yield was low due to glucose degradation. Overliming at pH 10 showed the highest yield of ethanol production. Various strains of Baker’s yeast (Saccharomyces cerevisiae) will be utilized to produce ethanol at the optimal overliming pH.

Keywords: Pennisetum polystachion, lignocellulosic biomass, bioethanol production, detoxification, overliming, Saccharomyces cerevisiae

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Authors: Yun-Chin Chung, Nileema Divate, Gen-Hung Chen, Pei-Ru Huang, Rupesh Divate

Abstract:

Many environmental factors, such as glucose concentration, ethanol, temperature, osmotic pressure and pH, decrease the production rate of ethanol using yeast as a starter. Fermentation starters with high tolerance to various stresses are always demanded for brewing industry. Trehalose, a storage carbohydrate in cell wall of yeast, plays an important role in tolerance of environmental stress by preserving integrity of plasma membrane and stabilizing proteins. Furan aldehydes are toxic to yeast and the growth rate of yeast is significantly reduced if furan aldehydes were present in the fermentation medium. In yeast, aldehyde reductase is involved in the detoxification of reactive aldehydes and consequently the growth of yeast is improved. The aims of this study were to construct a genetic recombinant Saccharomyces cerevisiae or Pichia pastoris with furfural and HMF degrading and high ethanol tolerance capacities. Yeast strains were engineered by genetic recombination for overexpression of trehalose-6-phosphate synthase gene (tps1) and aldehyde reductase gene (ari1). TPS1 gene was cloned from S. cerevisiae by reverse transcription-polymerase chain reaction (RT-PCR) and then ligated with pGAPZαC vector. The constructed vector, pGAPZC-tps1, was transformed to recombinant yeasts strain with overexpression of ari1. The transformants with pGAPZC-tps1-ari1 were generated called STA (S. cerevisiae) and PTA (P. pastoris) with overexpression of tps1, ari1. PCR with tps1-specific primers and western blot with his-tag confirmed the gene insertion and protein expression of tps1 in the transformants, respectively. The neutral trehalase gene (nth1) of STA was successfully deleted and the novel strain STAΔN will be used for further study, including the measurement of trehalose concentration and ethanol, furfural tolerance assay.

Keywords: genetic recombinant, yeast, ethanol tolerance, trehalase, aldehyde reductase

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Authors: Beata J. Lehka, Samuel A. Bradley, Frederik G. Hansson, Khem B. Adhikari, Daniela Rago, Paulina Rubaszka, Ahmad K. Haidar, Ling Chen, Lea G. Hansen, Olga Gudich, Konstantina Giannakou, Yoko Nakamura, Thomas Dugé de Bernonville, Konstantinos Koudounas, Sarah E. O’Connor, Vincent Courdavault, Jay D. Keasling, Jie Zhang, Michael K. Jensen

Abstract:

Monoterpenoid indole alkaloids (MIAs) represent a large class of natural plant products with marketed pharmaceutical activities against a wide range of applications, including cancer and mental disorders. Halogenated MIAs have shown improved pharmaceutical properties; however, characterisation and synthesis of new-to-nature halogenated MIAs remain a challenge in slow-growing plants with limited genetic tractability. Here, we demonstrate a platform for de novo biosynthesis of two bioactive MIAs, serpentine and alstonine, in baker’s yeast Saccharomyces cerevisiae, reaching titers of 8.85 mg/L and 4.48 mg/L, respectively, when cultivated in fed-batch micro bioreactors. Using this MIA biosynthesis platform, we undertake a systematic exploration of the derivative space surrounding these compounds and produce halogenated MIAs. The aim of the current study is to develop a fermentation process for halogenated MIAs.

Keywords: monoterpenoid indole alkaloids, Saccharomyces cerevisiae, halogenated derivatives, fermentation

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Authors: Jordi Cuñé, Carlos de Lecea, Laia Marti

Abstract:

Small molecules known as fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) are quickly fermented in the large intestine after being poorly absorbed in the small intestine. There is proof that individuals suffering from functional gastrointestinal disorders, like irritable bowel syndrome (IBS), observe an improvement while following a diet low in FODMAPs. Because wheat has a relatively high fructan content, it is a key source of FODMAPs in our diet. A yeast-based method was created in this study to lower the amounts of FODMAP in (whole wheat) bread. In contrast to fermentation by regular baker yeast, the combination of Kluyveromyces marxianus ABB S7 with Saccharomyces cerevisiae allowed a reduction of fructan content by 60% without implying the appearance of other substrates categorized as FODMAP (excess fructose or polyols). The final FODMAP content in the developed whole wheat bread would allow its classification as a safe product for sensitive people, according to international consensus. Cocultures of S. cerevisiae and K. marxianus were established in order to ensure sufficient CO₂ generation; larger quantities of gas were produced due to the strains' synergistic relationship. Thus, this method works well for lowering the levels of FODMAPs in bread.

Keywords: Kluyveromyces marxianus, bakery, bread, FODMAP, IBS, functional gastro intestinal disorders

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