Influence of Tannin Extract and Yeast Extract on Color Preservation and Anthocyanin Content of Mulberry Wine.

PubMed

You, Yilin; Li, Na; Han, Xue; Guo, Jielong; Liu, Guojie; Huang, Weidong; Zhan, Jicheng

2018-04-01

The color of mulberry wine is extremely unstable in processing and aging. This paper investigates the effects of tannin extract and yeast extract on the color and color-preserving characteristics of mulberry wine made from the Dashi cultivar. The results showed that the maximum absorption wavelength in both tannin extract and yeast extract groups changed generating the red shift effect. The color of the tannin extract maintained a good gloss in the first 4 months, while the yeast extract group showed remarkable color preservation for the first 3 months. The total anthocyanin and cyanidin-3-rutinoside contents in both experiment groups were significantly higher than that of the control group, thus proving that tannin extract and yeast extract both exert a remarkably positive effect on preserving the color of mulberry wine during its aging. Moreover, sensory analysis indicated that the quality of mulberry wine treated with tannin extract was significantly higher than that of the control. The distinct color of mulberry wine is one of the foremost qualities that imprints on consumers' senses, but it is extremely unstable in processing and aging. However, the color protection of mulberry wine was not studied previously. In this study, we found that tannin extract and yeast extract both exert a remarkably positive effect on preserving the color of mulberry wine during aging. The study is of great significance as a guide to improving the color stability of mulberry wine, thereby also improving and promoting the development of the mulberry deep processing industry. © 2018 Institute of Food Technologists®.

Inbuilt Potential of YEM Medium and Its Constituents to Generate Ag/Ag2O Nanoparticles

PubMed Central

Yamal, G.; Sharmila, P.; Rao, K. S.; Pardha-Saradhi, P.

2013-01-01

We discovered that Yeast Extract Mannitol (YEM) medium possessed immense potential to generate silver nanoparticles from AgNO3 upon autoclaving, which was evident from (i) alteration in color of the medium; (ii) peak at ∼410 nm in UV-Vis spectrum due to surface plasmon resonance specific to silver nanoparticles; and (iii) TEM investigations. TEM coupled with EDX confirmed that distinct nanoparticles were composed of silver. Yeast extract and mannitol were key components of YEM medium responsible for the formation of nanoparticles. PXRD analysis indicated crystalline geometry and Ag/Ag2O phases in nanoparticles generated with YEM medium, yeast extract and mannitol. Our investigations also revealed that both mannitol and yeast extract possessed potential to convert ∼80% of silver ions in 0.5 mM AgNO3 to nanoparticles, on autoclaving for 30 min at 121°C under a pressure of 1.06 kg/cm2. Addition of filter sterilized AgNO3 under ambient conditions to pre-autoclaved YEM medium and yeast extract brought about color change due to the formation of silver nanoparticles, but required prolonged duration. In general, even after 72 h intensity of color was significantly less than that recorded following autoclaving. Silver nanoparticles formed at room temperature were more heterogeneous compared to that obtained upon autoclaving. In summary, our findings demonstrated that (i) YEM medium and its constituents promote synthesis of silver nanoparticles; and (ii) autoclaving enhances rapid synthesis of silver nanoparticles by YEM medium, yeast extract and mannitol. PMID:23626722

Spent brewer's yeast extract as an ingredient in cooked hams.

PubMed

Pancrazio, Gaston; Cunha, Sara C; de Pinho, Paula Guedes; Loureiro, Mónica; Meireles, Sónia; Ferreira, Isabel M P L V O; Pinho, Olívia

2016-11-01

This work describes the effect of the incorporation of 1% spent yeast extract into cooked hams. Physical/chemical/sensorial characteristics and changes during 12 and 90days storage were evaluated on control and treated cooked hams processed for 1.5, 2.0, 2.5 or 3h. Spent yeast extract addition increased hardness, chewiness, ash, protein and free amino acid content. Similar volatile profiles were obtained, although there were some quantitative differences. No advantages were observed for increased cooking time. No significant differences were observed for physical and sensorial parameters of cooked hams with spent yeast extract at 12 and 90days post production, but His, aldehydes and esters increased at the end of storage. This behaviour was similar to that observed for control hams. The higher hardness of cooked ham with 1% yeast extract was due to the stronger gel formed during cooking and was maintained during storage. This additive acts as gel stabilizer for cooked ham production and could potentially improve other processing characteristics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dextransucrase production using cashew apple juice as substrate: effect of phosphate and yeast extract addition.

PubMed

Chagas, Clarice M A; Honorato, Talita L; Pinto, Gustavo A S; Maia, Geraldo A; Rodrigues, Sueli

2007-05-01

Cashew apples are considered agriculture excess in the Brazilian Northeast because cashew trees are cultivated primarily with the aim of cashew nut production. In this work, the use of cashew apple juice as a substrate for Leuconostoc mesenteroides cultivation was investigated. The effect of yeast extract and phosphate addition was evaluated using factorial planning tools. Both phosphate and yeast extract addition were significant factors for biomass growth, but had no significant effect on maximum enzyme activity. The enzyme activities found in cashew apple juice assays were at least 3.5 times higher than the activity found in the synthetic medium. Assays with pH control (pH = 6.5) were also carried out. The pH-controlled fermentation enhanced biomass growth, but decreased the enzyme activity. Crude enzyme free of cells produced using cashew apple juice was stable for 16 h at 30 degrees C at a pH of 5.0.

Extraction of genomic DNA from yeasts for PCR-based applications.

PubMed

Lõoke, Marko; Kristjuhan, Kersti; Kristjuhan, Arnold

2011-05-01

We have developed a quick and low-cost genomic DNA extraction protocol from yeast cells for PCR-based applications. This method does not require any enzymes, hazardous chemicals, or extreme temperatures, and is especially powerful for simultaneous analysis of a large number of samples. DNA can be efficiently extracted from different yeast species (Kluyveromyces lactis, Hansenula polymorpha, Schizosaccharomyces pombe, Candida albicans, Pichia pastoris, and Saccharomyces cerevisiae). The protocol involves lysis of yeast colonies or cells from liquid culture in a lithium acetate (LiOAc)-SDS solution and subsequent precipitation of DNA with ethanol. Approximately 100 nanograms of total genomic DNA can be extracted from 1 × 10(7) cells. DNA extracted by this method is suitable for a variety of PCR-based applications (including colony PCR, real-time qPCR, and DNA sequencing) for amplification of DNA fragments of ≤ 3500 bp.

Optimization of Culture Medium Enhances Viable Biomass Production and Biocontrol Efficacy of the Antagonistic Yeast, Candida diversa.

PubMed

Liu, Jia; Li, Guangkun; Sui, Yuan

2017-01-01

Viable biomass production is a key determinant of suitability of antagonistic yeasts as potential biocontrol agents. This study investigated the effects of three metal ions (magnesium, ferrous, and zinc) on biomass production and viability of the antagonistic yeast, Candida diversa . Using response surface methodology to optimize medium components, a maximum biomass was obtained, when the collective Mg 2+ , Fe 2+ , and Zn 2+ concentrations were adjusted in a minimal mineral (MM) medium. Compared with the unmodified MM, and three ion-deficient MM media, yeast cells cultured in the three ion-modified MM medium exhibited a lower level of cellular oxidative damage, and a higher level of antioxidant enzyme activity. A biocontrol assay indicated that C. diversa grown in the ion-modified MM exhibited the greatest level of control of gray mold on apple fruit. These results provide new information on culture medium optimization to grow yeast antagonists in order to improve biomass production and biocontrol efficacy.

Optimization of Culture Medium Enhances Viable Biomass Production and Biocontrol Efficacy of the Antagonistic Yeast, Candida diversa

PubMed Central

Liu, Jia; Li, Guangkun; Sui, Yuan

2017-01-01

Viable biomass production is a key determinant of suitability of antagonistic yeasts as potential biocontrol agents. This study investigated the effects of three metal ions (magnesium, ferrous, and zinc) on biomass production and viability of the antagonistic yeast, Candida diversa. Using response surface methodology to optimize medium components, a maximum biomass was obtained, when the collective Mg2+, Fe2+, and Zn2+ concentrations were adjusted in a minimal mineral (MM) medium. Compared with the unmodified MM, and three ion-deficient MM media, yeast cells cultured in the three ion-modified MM medium exhibited a lower level of cellular oxidative damage, and a higher level of antioxidant enzyme activity. A biocontrol assay indicated that C. diversa grown in the ion-modified MM exhibited the greatest level of control of gray mold on apple fruit. These results provide new information on culture medium optimization to grow yeast antagonists in order to improve biomass production and biocontrol efficacy. PMID:29089939

CHROMagar Candida as the Sole Primary Medium for Isolation of Yeasts and as a Source Medium for the Rapid-Assimilation-of-Trehalose Test

PubMed Central

Murray, Melissa P.; Zinchuk, Riva; Larone, Davise H.

2005-01-01

The chromogenic medium BBL CHROMagar Candida (CAC) was evaluated as a sole primary medium for the isolation of yeasts from clinical specimens in which yeasts are the primary concern. Additionally, the reliability of the rapid-assimilation-of-trehalose (RAT) test in yielding correct results with isolates taken from CAC was assessed. A total of 270 throat, urine, and genital (TUG) specimens were streaked onto CAC, Sabouraud dextrose agar (SDA), inhibitory mold agar (IMA), and Mycosel (MYC). A total of 69 blood culture broths that were smear positive for yeast were streaked onto CAC and SDA. A 1-h RAT test (NCCLS M35-A) was performed simultaneously on isolates from CAC and SDA. A total of 112 TUG specimens yielded yeast colonies (CAC, 111 colonies; IMA, 105; SDA, 103; MYC, 91). The 69 blood culture yeasts grew on both CAC and SDA. Mixed cultures of yeasts were detected on 11 CAC plates but were unrecognized on other media. Colonies suspected of being C. glabrata on 32 CAC plates were all RAT test positive and confirmed to be C. glabrata; of 59 colonies with various characteristics of color and morphology on CAC, none were RAT positive, and all were conventionally identified as yeasts other than C. glabrata (sensitivity and specificity, 100%). The same isolates from SDA tested for RAT produced six false negatives and no false positives (sensitivity, 81%; specificity, 100%). The results show that CAC can be used as the sole primary medium for recovery of yeasts from clinical specimens. Additionally, isolates grown on CAC yield excellent results with the RAT test utilized in this study. PMID:15750085

CHROMagar Candida as the sole primary medium for isolation of yeasts and as a source medium for the rapid-assimilation-of-trehalose test.

PubMed

Murray, Melissa P; Zinchuk, Riva; Larone, Davise H

2005-03-01

The chromogenic medium BBL CHROMagar Candida (CAC) was evaluated as a sole primary medium for the isolation of yeasts from clinical specimens in which yeasts are the primary concern. Additionally, the reliability of the rapid-assimilation-of-trehalose (RAT) test in yielding correct results with isolates taken from CAC was assessed. A total of 270 throat, urine, and genital (TUG) specimens were streaked onto CAC, Sabouraud dextrose agar (SDA), inhibitory mold agar (IMA), and Mycosel (MYC). A total of 69 blood culture broths that were smear positive for yeast were streaked onto CAC and SDA. A 1-h RAT test (NCCLS M35-A) was performed simultaneously on isolates from CAC and SDA. A total of 112 TUG specimens yielded yeast colonies (CAC, 111 colonies; IMA, 105; SDA, 103; MYC, 91). The 69 blood culture yeasts grew on both CAC and SDA. Mixed cultures of yeasts were detected on 11 CAC plates but were unrecognized on other media. Colonies suspected of being C. glabrata on 32 CAC plates were all RAT test positive and confirmed to be C. glabrata; of 59 colonies with various characteristics of color and morphology on CAC, none were RAT positive, and all were conventionally identified as yeasts other than C. glabrata (sensitivity and specificity, 100%). The same isolates from SDA tested for RAT produced six false negatives and no false positives (sensitivity, 81%; specificity, 100%). The results show that CAC can be used as the sole primary medium for recovery of yeasts from clinical specimens. Additionally, isolates grown on CAC yield excellent results with the RAT test utilized in this study.

Flavins contained in yeast extract are exploited for anodic electron transfer by Lactococcus lactis.

PubMed

Masuda, Masaki; Freguia, Stefano; Wang, Yung-Fu; Tsujimura, Seiya; Kano, Kenji

2010-06-01

Cyclic voltammograms of yeast extract-containing medium exhibit a clear redox peak around -0.4V vs. Ag|AgCl. Fermentative bacterium Lactococcus lactis was hereby shown to exploit this redox compound for extracellular electron transfer towards a graphite anode using glucose as an electron donor. High performance liquid chromatography revealed that this may be a flavin-type compound. The ability of L. lactis to exploit exogenous flavins for anodic glucose oxidation was confirmed by tests where flavin-type compounds were supplied to the bacterium in well defined media. Based on its mid-point potential, riboflavin can be regarded as a near-optimal mediator for microbially catalyzed anodic electron transfer. Riboflavin derivative flavin mononucleotide (FMN) was also exploited by L. lactis as a redox shuttle, unlike flavin adenine dinucleotide (FAD), possibly due to the absence of a specific transporter for the latter. The use of yeast extract in microbial fuel cell media is herein discouraged based on the related unwanted artificial addition of redox mediators which may distort experimental results. Copyright 2009 Elsevier B.V. All rights reserved.

Cashew apple juice as microbial cultivation medium for non-immunogenic hyaluronic acid production.

PubMed

Oliveira, Adriano H; Ogrodowski, Cristiane C; de Macedo, André C; Santana, Maria Helena A; Gonçalves, Luciana R B

2013-12-01

In this work, natural cashew apple juice was used as cultivation medium as an alternative to substitute brain heart infusion medium. The effect of aeration and juice supplementation with yeast extract on the production of hyaluronic acid in batch fermentation was also investigated. Similar levels of cell mass were obtained in inoculum using cashew apple juice supplemented with yeast extract or the conventional brain heart infusion medium. Fermentation in Erlenmeyer flasks produced low biomass and hyaluronic acid concentrations. The hyaluronic acid concentration and viscosity increased from 0.15 g/L and 3.87 cP (no aeration or medium supplementation) to 1.76 g/L and 107 cP, when aeration (2 vvm) and 60 g/L of yeast extract were used. The results suggest the production of low-molecular weight hyaluronic acid oligomers instead of the high molecular weight polymer.

Cashew apple juice as microbial cultivation medium for non-immunogenic hyaluronic acid production

PubMed Central

Oliveira, Adriano H.; Ogrodowski, Cristiane C.; de Macedo, André C.; Santana, Maria Helena A.; Gonçalves, Luciana R.B.

2013-01-01

In this work, natural cashew apple juice was used as cultivation medium as an alternative to substitute brain heart infusion medium. The effect of aeration and juice supplementation with yeast extract on the production of hyaluronic acid in batch fermentation was also investigated. Similar levels of cell mass were obtained in inoculum using cashew apple juice supplemented with yeast extract or the conventional brain heart infusion medium. Fermentation in Erlenmeyer flasks produced low biomass and hyaluronic acid concentrations. The hyaluronic acid concentration and viscosity increased from 0.15 g/L and 3.87 cP (no aeration or medium supplementation) to 1.76 g/L and 107 cP, when aeration (2 vvm) and 60 g/L of yeast extract were used. The results suggest the production of low-molecular weight hyaluronic acid oligomers instead of the high molecular weight polymer. PMID:24688498

40 CFR 180.1246 - Yeast Extract Hydrolysate from Saccharomyces cerevisiae: exemption from the requirement of a...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Yeast Extract Hydrolysate from... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1246 Yeast Extract Hydrolysate from... exemption from the requirement of a tolerance for residues of the biochemical pesticide Yeast Extract...

40 CFR 180.1246 - Yeast Extract Hydrolysate from Saccharomyces cerevisiae: exemption from the requirement of a...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Yeast Extract Hydrolysate from... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1246 Yeast Extract Hydrolysate from... exemption from the requirement of a tolerance for residues of the biochemical pesticide Yeast Extract...

40 CFR 180.1246 - Yeast Extract Hydrolysate from Saccharomyces cerevisiae: exemption from the requirement of a...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Yeast Extract Hydrolysate from... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1246 Yeast Extract Hydrolysate from... exemption from the requirement of a tolerance for residues of the biochemical pesticide Yeast Extract...

40 CFR 180.1246 - Yeast Extract Hydrolysate from Saccharomyces cerevisiae: exemption from the requirement of a...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Yeast Extract Hydrolysate from... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1246 Yeast Extract Hydrolysate from... exemption from the requirement of a tolerance for residues of the biochemical pesticide Yeast Extract...

Vegemite Beer: yeast extract spreads as nutrient supplements to promote fermentation.

PubMed

Kerr, Edward D; Schulz, Benjamin L

2016-01-01

Vegemite is an iconic Australian food spread made from spent brewers' yeast extract, which has been reported to be used as an ingredient in illegal home brewing. In this study, we tested the utility of Vegemite and the similar spread Marmite in promoting fermentation. We could not culture microorganisms from either Vegemite or Marmite, consistent with these food-grade spreads being essentially sterile. To test if the addition of Vegemite or Marmite could assist in fermentation when additional viable yeast was also present, solutions containing glucose and a range of concentrations of either Vegemite or Marmite were inoculated with brewers' yeast. No fermentation occurred in any condition without addition of extra brewer's yeast. Fermentation did not occur when yeast was inoculated into solutions containing only glucose, but progressed efficiently with when Vegemite or Marmite was also added. Gas Chromatography confirmed that ethanol was present at ∼3% v/v post-fermentation in all samples which contained glucose, Vegemite or Marmite, and brewers' yeast. Trace amounts of methanol were also detected. Mass spectrometry proteomics identified abundant intracellular yeast proteins and barley proteins in Vegemite and Marmite, and abundant secreted yeast proteins from actively growing yeast in those samples to which extra brewers' yeast had been added. We estimate that the real-world cost of home brewed "Vegemite Beer" would be very low. Our results show that Vegemite or other yeast extract spreads could provide cheap and readily available sources of nutrient supplementation to increase the efficiency of fermentation in home brewing or other settings.

Medium-Scale Production of Citrinin by Penicillium citrinum in a Semisynthetic Medium

PubMed Central

Davis, N. D.; Dalby, D. K.; Diener, U. L.; Sansing, G. A.

1975-01-01

A convenient method is described for the production of up to 1.75 g of citrinin per liter by Penicillium citrinum growing in stationary culture in a 5-gallon (18.925 liters) carboy containing 4 liters of 4% sucrose and 2% yeast extract medium. PMID:1089161

Enumeration and rapid identification of yeasts during extraction processes of extra virgin olive oil in Tuscany.

PubMed

Mari, Eleonora; Guerrini, Simona; Granchi, Lisa; Vincenzini, Massimo

2016-06-01

The aim of this study was to evaluate the occurrence of yeast populations during different olive oil extraction processes, carried out in three consecutive years in Tuscany (Italy), by analysing crushed pastes, kneaded pastes, oil from decanter and pomaces. The results showed yeast concentrations ranging between 10(3) and 10(5) CFU/g or per mL. Seventeen dominant yeast species were identified by random amplified polymorphic DNA with primer M13 and their identification was confirmed by restriction fragments length polymorphism of ribosomal internal transcribed spacer and sequencing rRNA genes. The isolation frequencies of each species in the collected samples pointed out that the occurrence of the various yeast species in olive oil extraction process was dependent not only on the yeasts contaminating the olives but also on the yeasts colonizing the plant for oil extraction. In fact, eleven dominant yeast species were detected from the washed olives, but only three of them were also found in oil samples at significant isolation frequency. On the contrary, the most abundant species in oil samples, Yamadazyma terventina, did not occur in washed olive samples. These findings suggest a phenomenon of contamination of the plant for oil extraction that selects some yeast species that could affect the quality of olive oil.

A Simple and Rapid Protocol for Producing Yeast Extract from Saccharomyces cerevisiae Suitable for Preparing Bacterial Culture Media

PubMed Central

Zarei, Omid; Dastmalchi, Siavoush; Hamzeh-Mivehroud, Maryam

2016-01-01

Yeasts, especially Saccharomyces cerevisiae, are one of the oldest organisms with broad spectrum of applications, owing to their unique genetics and physiology. Yeast extract, i.e. the product of yeast cells, is extensively used as nutritional resource in bacterial culture media. The aim of this study was to develop a simple, rapid and cost benefit process to produce the yeast extract. In this procedure mechanical methods such as high temperature and pressure were utilized to produce the yeast extract. The growth of the bacteria feed with the produced yeast extract was monitored in order to assess the quality of the product. The results showed that the quality of the produced yeast extract was very promising concluded from the growth pattern of bacterial cells in media prepared from this product and was comparable with that of the three commercial yeast extracts in terms of bacterial growth properties. One of the main advantages of the current method was that no chemicals and enzymes were used, leading to the reduced production cost. The method is very simple and cost effective, and can be performed in a reasonable time making it suitable for being adopted by research laboratories. Furthermore, it can be scaled up to produce large quantities for industrial applications. PMID:28243289

Antioxidant Properties of Crude Extract, Partition Extract, and Fermented Medium of Dendrobium sabin Flower

PubMed Central

Abu, Farahziela; Mohd Akhir, Sobri

2017-01-01

Antioxidant properties of crude extract, partition extract, and fermented medium from Dendrobium sabin (DS) flower were investigated. The oven-dried DS flower was extracted using 100% methanol (w/v), 100% ethanol (w/v), and 100% water (w/v). The 100% methanolic crude extract showed the highest total phenolic content (40.33 ± mg GAE/g extract) and the best antioxidant properties as shown by DPPH, ABTS, and FRAP assays. A correlation relationship between antioxidant activity and total phenolic content showed that phenolic compounds were the dominant antioxidant components in this flower extract. The microbial fermentation on DS flower medium showed a potential in increasing the phenolic content and DPPH scavenging activity. The TPC of final fermented medium showed approximately 18% increment, while the DPPH of fermented medium increased significantly to approximately 80% at the end of the fermentation. Dendrobium sabin (DS) flower showed very good potential properties of antioxidant in crude extract and partition extract as well as better antioxidant activity in the flower fermented medium. PMID:28761496

Liquid chromatographic extraction medium

DOEpatents

Horwitz, E. Philip; Dietz, Mark L.

1994-01-01

A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

Liquid chromatographic extraction medium

DOEpatents

Horwitz, E.P.; Dietz, M.L.

1994-09-13

A method and apparatus are disclosed for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water. 1 fig.

Citric acid production from extract of Jerusalem artichoke tubers by the genetically engineered yeast Yarrowia lipolytica strain 30 and purification of citric acid.

PubMed

Wang, Ling-Fei; Wang, Zhi-Peng; Liu, Xiao-Yan; Chi, Zhen-Ming

2013-11-01

In this study, citric acid production from extract of Jerusalem artichoke tubers by the genetically engineered yeast Yarrowia lipolytica strain 30 was investigated. After the compositions of the extract of Jerusalem artichoke tubers for citric acid production were optimized, the results showed that natural components of extract of Jerusalem artichoke tubers without addition of any other components were suitable for citric acid production by the yeast strain. During 10 L fermentation using the extract containing 84.3 g L(-1) total sugars, 68.3 g L(-1) citric acid was produced and the yield of citric acid was 0.91 g g(-1) within 336 h. At the end of the fermentation, 9.2 g L(-1) of residual total sugar and 2.1 g L(-1) of reducing sugar were left in the fermented medium. At the same time, citric acid in the supernatant of the culture was purified. It was found that 67.2 % of the citric acid in the supernatant of the culture was recovered and purity of citric acid in the crystal was 96 %.

Screening of plant extracts for antimicrobial activity against bacteria and yeasts with dermatological relevance.

PubMed

Weckesser, S; Engel, K; Simon-Haarhaus, B; Wittmer, A; Pelz, K; Schempp, C M

2007-08-01

There is cumulative resistance against antibiotics of many bacteria. Therefore, the development of new antiseptics and antimicrobial agents for the treatment of skin infections is of increasing interest. We have screened six plant extracts and isolated compounds for antimicrobial effects on bacteria and yeasts with dermatological relevance. The following plant extracts have been tested: Gentiana lutea, Harpagophytum procumbens, Boswellia serrata (dry extracts), Usnea barbata, Rosmarinus officinalis and Salvia officinalis (supercritical carbon dioxide [CO2] extracts). Additionally, the following characteristic plant substances were tested: usnic acid, carnosol, carnosic acid, ursolic acid, oleanolic acid, harpagoside, boswellic acid and gentiopicroside. The extracts and compounds were tested against 29 aerobic and anaerobic bacteria and yeasts in the agar dilution test. U. barbata-extract and usnic acid were the most active compounds, especially in anaerobic bacteria. Usnea CO2-extract effectively inhibited the growth of several Gram-positive bacteria like Staphylococcus aureus (including methicillin-resistant strains - MRSA), Propionibacterium acnes and Corynebacterium species. Growth of the dimorphic yeast Malassezia furfur was also inhibited by Usnea-extract. Besides the Usnea-extract, Rosmarinus-, Salvia-, Boswellia- and Harpagophytum-extracts proved to be effective against a panel of bacteria. It is concluded that due to their antimicrobial effects some of the plant extracts may be used for the topical treatment of skin disorders like acne vulgaris and seborrhoic eczema.

Isolation and characterization of ethanol tolerant yeast strains

PubMed Central

Tikka, Chiranjeevi; Osuru, Hari Prasad; Atluri, Navya; Raghavulu, Praveen Chakravarthi Veera; yellapu, Nanda Kumar; Mannur, Ismail Shaik; Prasad, Uppu Venkateswara; Aluru, Sudheer; K, Narasimha Varma; Bhaskar, Matcha

2013-01-01

Yeast strains are commonly associated with sugar rich environments. Various fruit samples were selected as source for isolating yeast cells. The isolated cultures were identified at Genus level by colony morphology, biochemical characteristics and cell morphological characters. An attempt has been made to check the viability of yeast cells under different concentrations of ethanol. Ethanol tolerance of each strain was studied by allowing the yeast to grow in liquid YEPD (Yeast Extract Peptone Dextrose) medium having different concentrations of ethanol. A total of fifteen yeast strains isolated from different samples were used for the study. Seven strains of Saccharomyces cerevisiae obtained from different fruit sources were screened for ethanol tolerance. The results obtained in this study show a range of tolerance levels between 7%-12% in all the stains. Further, the cluster analysis based on 22 RAPD (Random Amplified polymorphic DNA) bands revealed polymorphisms in these seven Saccharomyces strains. PMID:23750092

Optimization of Culture Medium for the Growth of Candida sp. and Blastobotrys sp. as Starter Culture in Fermentation of Cocoa Beans (Theobroma cacao) Using Response Surface Methodology (RSM).

PubMed

Mahazar, N H; Zakuan, Z; Norhayati, H; MeorHussin, A S; Rukayadi, Y

2017-01-01

Inoculation of starter culture in cocoa bean fermentation produces consistent, predictable and high quality of fermented cocoa beans. It is important to produce healthy inoculum in cocoa bean fermentation for better fermented products. Inoculum could minimize the length of the lag phase in fermentation. The purpose of this study was to optimize the component of culture medium for the maximum cultivation of Candida sp. and Blastobotrys sp. Molasses and yeast extract were chosen as medium composition and Response Surface Methodology (RSM) was then employed to optimize the molasses and yeast extract. Maximum growth of Candida sp. (7.63 log CFU mL-1) and Blastobotrys sp. (8.30 log CFU mL-1) were obtained from the fermentation. Optimum culture media for the growth of Candida sp., consist of 10% (w/v) molasses and 2% (w/v) yeast extract, while for Blastobotrys sp., were 1.94% (w/v) molasses and 2% (w/v) yeast extract. This study shows that culture medium consists of molasses and yeast extract were able to produce maximum growth of Candida sp. and Blastobotrys sp., as a starter culture for cocoa bean fermentation.

Chlorhexidine: beta-cyclodextrin inhibits yeast growth by extraction of ergosterol.

PubMed

Teixeira, K I R; Araújo, P V; Sinisterra, R D; Cortés, M E

2012-04-01

Chlorhexidine (Cx) augmented with beta-cyclodextrin (β-cd) inclusion compounds, termed Cx:β-cd complexes, have been developed for use as antiseptic agents. The aim of this study was to examine the interactions of Cx:β-cd complexes, prepared at different molecular ratios, with sterol and yeast membranes. The Minimal Inhibitory Concentration (MIC) against the yeast Candida albicans (C.a.) was determined for each complex; the MICs were found to range from 0.5 to 2 μg/mL. To confirm the MIC data, quantitative analysis of viable cells was performed using trypan blue staining. Mechanistic characterization of the interactions that the Cx:β-cd complexes have with the yeast membrane and assessment of membrane morphology following exposure to Cx:β-cd complexes were performed using Sterol Quantification Method analysis (SQM) and scanning electron microscopy (SEM). SQM revealed that sterol extraction increased with increasing β-cd concentrations (1.71 ×10(3); 1.4 ×10(3); 3.45 ×10(3), and 3.74 ×10(3) CFU for 1:1, 1:2, 1:3, and 1:4, respectively), likely as a consequence of membrane ergosterol solubilization. SEM images demonstrated that cell membrane damage is a visible and significant mechanism that contributes to the antimicrobial effects of Cx:β-cd complexes. Cell disorganization increased significantly as the proportion of β-cyclodextrin present in the complex increased. Morphology of cells exposed to complexes with 1:3 and 1:4 molar ratios of Cx:β-cd were observed to have large aggregates mixed with yeast remains, representing more membrane disruption than that observed in cells treated with Cx alone. In conclusion, nanoaggregates of Cx:β-cd complexes block yeast growth via ergosterol extraction, permeabilizing the membrane by creating cluster-like structures within the cell membrane, possibly due to high amounts of hydrogen bonding.

Systematic identification of yeast proteins extracted into model wine during aging on the yeast lees.

PubMed

Rowe, Jeffrey D; Harbertson, James F; Osborne, James P; Freitag, Michael; Lim, Juyun; Bakalinsky, Alan T

2010-02-24

Total protein and protein-associated mannan concentrations were measured, and individual proteins were identified during extraction into model wines over 9 months of aging on the yeast lees following completion of fermentations by seven wine strains of Saccharomyces cerevisiae. In aged wines, protein-associated mannan increased about 6-fold (+/-66%), while total protein only increased 2-fold (+/-20%), which resulted in a significantly greater protein-associated mannan/total protein ratio for three strains. A total of 219 proteins were identified among all wine samples taken over the entire time course. Of the 17 "long-lived" proteins detected in all 9 month samples, 13 were cell wall mannoproteins, and four were glycolytic enzymes. Most cytosolic proteins were not detected after 6 months. Native mannosylated yeast invertase was assayed for binding to wine tannin and was found to have a 10-fold lower affinity than nonglycosylated bovine serum albumin. Enrichment of mannoproteins in the aged model wines implies greater solution stability than other yeast proteins and the possibility that their contributions to wine quality may persist long after bottling.

Improvement on the productivity of continuous tequila fermentation by Saccharomyces cerevisiae of Agave tequilana juice with supplementation of yeast extract and aeration.

PubMed

Hernández-Cortés, Guillermo; Valle-Rodríguez, Juan Octavio; Herrera-López, Enrique J; Díaz-Montaño, Dulce María; González-García, Yolanda; Escalona-Buendía, Héctor B; Córdova, Jesús

2016-12-01

Agave (Agave tequilana Weber var. azul) fermentations are traditionally carried out employing batch systems in the process of tequila manufacturing; nevertheless, continuous cultures could be an attractive technological alternative to increase productivity and efficiency of sugar to ethanol conversion. However, agave juice (used as a culture medium) has nutritional deficiencies that limit the implementation of yeast continuous fermentations, resulting in high residual sugars and low fermentative rates. In this work, fermentations of agave juice using Saccharomyces cerevisiae were put into operation to prove the necessity of supplementing yeast extract, in order to alleviate nutritional deficiencies of agave juice. Furthermore, continuous fermentations were performed at two different aeration flow rates, and feeding sterilized and non-sterilized media. The obtained fermented musts were subsequently distilled to obtain tequila and the preference level was compared against two commercial tequilas, according to a sensorial analysis. The supplementation of agave juice with air and yeast extract augmented the fermentative capacity of S. cerevisiae S1 and the ethanol productivities, compared to those continuous fermentations non supplemented. In fact, aeration improved ethanol production from 37 to 40 g L(-1), reducing sugars consumption from 73 to 88 g L(-1) and ethanol productivity from 3.0 to 3.2 g (Lh)(-1), for non-aerated and aerated (at 0.02 vvm) cultures, respectively. Supplementation of yeast extract allowed an increase in specific growth rate and dilution rates (0.12 h(-1), compared to 0.08 h(-1) of non-supplemented cultures), ethanol production (47 g L(-1)), reducing sugars consumption (93 g L(-1)) and ethanol productivity [5.6 g (Lh)(-1)] were reached. Additionally, the effect of feeding sterilized or non-sterilized medium to the continuous cultures was compared, finding no significant differences between both types of cultures. The overall effect

The implementation of high fermentative 2,3-butanediol production from xylose by simultaneous additions of yeast extract, Na2EDTA, and acetic acid.

PubMed

Wang, Xiao-Xiong; Hu, Hong-Ying; Liu, De-Hua; Song, Yuan-Quan

2016-01-25

The effective use of xylose may significantly enhance the feasibility of using lignocellulosic hydrolysate to produce 2,3-butanediol (2,3-BD). Previous difficulties in 2,3-BD production include that the high-concentration xylose cannot be converted completely and the fermentation rate is slow. This study investigated the effects of yeast extract, ethylenediaminetetraacetic acid disodium salt (Na2EDTA), and acetic acid on 2,3-BD production from xylose. The central composite design approach was used to optimize the concentrations of these components. It was found that simultaneous addition of yeast extract, Na2EDTA, and acetic acid could significantly improve 2,3-BD production. The optimal concentrations of yeast extract, Na2EDTA, and acetic acid were 35.2, 1.2, and 4.5 g/L, respectively. The 2,3-BD concentration in the optimized medium reached 39.7 g/L after 48 hours of shake flask fermentation, the highest value ever reported in such a short period. The xylose utilization ratio and the 2,3-BD concentration increased to 99.0% and 42.7 g/L, respectively, after 48 hours of stirred batch fermentation. Furthermore, the 2,3-BD yield was 0.475 g/g, 95.0% of the theoretical maximum value. As the major components of lignocellulosic hydrolysate are glucose, xylose, and acetic acid, the results of this study indicate the possibility of directly using the hydrolysate to effectively produce 2,3-BD. Copyright © 2015 Elsevier B.V. All rights reserved.

[Effects of 33% grapefruit extract on the growth of the yeast--like fungi, dermatopytes and moulds].

PubMed

Krajewska-Kułak, E; Lukaszuk, C; Niczyporuk, W

2001-01-01

Grapefruit seed extract was discovered by Jacob Harich an american immunologist in 1980. Assessment of the influence of grapefruit extract on the yeast-like fungi strains--Candida albicans growth. Material used in this investigation was ATCC test Candida albicans strains no 10231, 200 of Candida albicans strains, 5 of Candida sp. strains isolated from patients with candidiasis symptoms from different ontocenosis and 12 of dermatophytes and moulds isolated from patients. The susceptibility of the Candida was determined by serial dilution method. It seems that 33% grapefruit extract exert a potent antifungal activity against the yeast like fungi strains and had low activity against dermatophytes and moulds. Further studies in vitro and in vivo on greater number of the yeast-like fungi strains and other fungi species are needed.

Optimization of Milk-Based Medium for Efficient Cultivation of Bifidobacterium pseudocatenulatum G4 Using Face-Centered Central Composite-Response Surface Methodology

PubMed Central

Abdul Khalil, Khalilah; Mustafa, Shuhaimi; Mohammad, Rosfarizan; Bin Ariff, Arbakariya; Shaari, Yamin; Abdul Manap, Yazid; Dahalan, Farrah Aini

2014-01-01

This study was undertaken to optimize skim milk and yeast extract concentration as a cultivation medium for optimal Bifidobacteria pseudocatenulatum G4 (G4) biomass and β-galactosidase production as well as lactose and free amino nitrogen (FAN) balance after cultivation period. Optimization process in this study involved four steps: screening for significant factors using 23 full factorial design, steepest ascent, optimization using FCCD-RSM, and verification. From screening steps, skim milk and yeast extract showed significant influence on the biomass production and, based on the steepest ascent step, middle points of skim milk (6% wt/vol) and yeast extract (1.89% wt/vol) were obtained. A polynomial regression model in FCCD-RSM revealed that both factors were found significant and the strongest influence was given by skim milk concentration. Optimum concentrations of skim milk and yeast extract for maximum biomass G4 and β-galactosidase production meanwhile low in lactose and FAN balance after cultivation period were 5.89% (wt/vol) and 2.31% (wt/vol), respectively. The validation experiments showed that the predicted and experimental values are not significantly different, indicating that the FCCD-RSM model developed is sufficient to describe the cultivation process of G4 using skim-milk-based medium with the addition of yeast extract. PMID:24527457

Strategy for the extraction of yeast DNA from artisan agave must for quantitative PCR analysis.

PubMed

Kirchmayr, Manuel Reinhart; Segura-Garcia, Luis Eduardo; Flores-Berrios, Ericka Patricia; Gschaedler, Anne

2011-11-01

An efficient method for the direct extraction of yeast genomic DNA from agave must was developed. The optimized protocol, which was based on silica-adsorption of DNA on microcolumns, included an enzymatic cell wall degradation step followed by prolonged lysis with hot detergent. The resulting extracts were suitable templates for subsequent qPCR assays that quantified mixed yeast populations in artisan Mexican mezcal fermentations. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Toxicology of the aqueous extract from the flowers of Butea monosperma Lam. and it's metabolomics in yeast cells.

PubMed

Khan, Washim; Gupta, Shreesh; Ahmad, Sayeed

2017-10-01

Due to lack of scientific evidence for the safety of Butea monosperma (Fabaceae), our study aimed to carry out its toxicological profile and to identify its metabolic pattern in yeast cell. The effect of aqueous extract of B. monosperma flower on glucose uptake in yeast cell was evaluated through optimizing pH, temperature, incubation time, substrate concentration and kinetic parameters. Further, the metabolic pattern of extract as such and in yeast cell were analyzed by gas chromatography-mass spectrometry. Mice were administered aqueous extract up to 6000 and 4000 mg/kg for acute oral and intraperitoneal toxicity, respectively, while up to 4500 mg/kg for sub-acute oral toxicity (30 days). Elongation in the lag and log phase was observed in yeast cells supplemented with extract as compared to control. A maximum of 184.9% glucose uptake was observed whereas kinetic parameters (K m and V max ) were 1.38 and 41.91 mol/s, respectively. Out of 75 metabolites found in the extract, 14 and 18 metabolites were utilized by yeast cell after 15 and 30 min of incubation, respectively. The LD 50 of extract administered through intraperitoneal route was estimated to be 3500 mg/kg. The extract did not elicit any significant difference (P ≥ 0.05) in weight gain, food consumption, water intake, hematological, biochemical parameters and histological changes as compared to the normal control. Results ascertained the safety of B. monosperma flower extract which can be explored as potential candidates for the development of anti-diabetic phytopharmaceuticals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of a semidefined growth medium for Pedobacter cryoconitis BG5 using statistical experimental design.

PubMed

Ong, Magdalena; Ongkudon, Clarence M; Wong, Clemente Michael Vui Ling

2016-10-02

Pedobacter cryoconitis BG5 are psychrophiles isolated from the cold environment and capable of proliferating and growing well at low temperature regime. Their cellular products have found a broad spectrum of applications, including in food, medicine, and bioremediation. Therefore, it is imperative to develop a high-cell density cultivation strategy coupled with optimized growth medium for P. cryoconitis BG5. To date, there has been no published report on the design and optimization of growth medium for P. cryoconitis, hence the objective of this research project. A preliminary screening of four commercially available media, namely tryptic soy broth, R2A, Luria Bertani broth, and nutrient broth, was conducted to formulate the basal medium. Based on the preliminary screening, tryptone, glucose, NaCl, and K2HPO4 along with three additional nutrients (yeast extract, MgSO4, and NH4Cl) were identified to form the basal medium which was further analyzed by Plackett-Burman experimental design. Central composite experimental design using response surface methodology was adopted to optimize tryptone, yeast extract, and NH4Cl concentrations in the formulated growth medium. Statistical data analysis showed a high regression factor of 0.84 with a predicted optimum optical (600 nm) cell density of 7.5 using 23.7 g/L of tryptone, 8.8 g/L of yeast extract, and 0.7 g/L of NH4Cl. The optimized medium for P. cryoconitis BG5 was tested, and the observed optical density was 7.8. The cost-effectiveness of the optimized medium was determined as 6.25 unit prices per gram of cell produced in a 250-ml Erlenmeyer flask.

Screening of intact yeasts and cell extracts to reduce Scrapie prions during biotransformation of food waste.

PubMed

Huyben, David; Boqvist, Sofia; Passoth, Volkmar; Renström, Lena; Allard Bengtsson, Ulrika; Andréoletti, Olivier; Kiessling, Anders; Lundh, Torbjörn; Vågsholm, Ivar

2018-02-08

Yeasts can be used to convert organic food wastes to protein-rich animal feed in order to recapture nutrients. However, the reuse of animal-derived waste poses a risk for the transmission of infectious prions that can cause neurodegeneration and fatality in humans and animals. The aim of this study was to investigate the ability of yeasts to reduce prion activity during the biotransformation of waste substrates-thereby becoming a biosafety hurdle in such a circular food system. During pre-screening, 30 yeast isolates were spiked with Classical Scrapie prions and incubated for 72 h in casein substrate, as a waste substitute. Based on reduced Scrapie seeding activity, waste biotransformation and protease activities, intact cells and cell extracts of 10 yeasts were further tested. Prion analysis showed that five yeast species reduced Scrapie seeding activity by approximately 1 log10 or 90%. Cryptococcus laurentii showed the most potential to reduce prion activity since both intact and extracted cells reduced Scrapie by 1 log10 and achieved the highest protease activity. These results show that select forms of yeast can act as a prion hurdle during the biotransformation of waste. However, the limited ability of yeasts to reduce prion activity warrants caution as a sole barrier to transmission as higher log reductions are needed before using waste-cultured yeast in circular food systems.

In Vivo Hypocholesterolemic Effect of MARDI Fermented Red Yeast Rice Water Extract in High Cholesterol Diet Fed Mice

PubMed Central

Beh, Boon Kee; Kong, Joan; Ho, Wan Yong; Mohd Yusof, Hamidah; Hussin, Aminuddin bin; Jaganath, Indu Bala; Alitheen, Noorjahan Banu; Jamaluddin, Anisah

2014-01-01

Fermented red yeast rice has been traditionally consumed as medication in Asian cuisine. This study aimed to determine the in vivo hypocholesterolemic and antioxidant effects of fermented red yeast rice water extract produced using Malaysian Agricultural Research and Development Institute (MARDI) Monascus purpureus strains in mice fed with high cholesterol diet. Absence of monacolin-k, lower level of γ-aminobutyric acid (GABA), higher content of total amino acids, and antioxidant activities were detected in MARDI fermented red yeast rice water extract (MFRYR). In vivo MFRYR treatment on hypercholesterolemic mice recorded similar lipid lowering effect as commercial red yeast rice extract (CRYR) as it helps to reduce the elevated serum liver enzyme and increased the antioxidant levels in liver. This effect was also associated with the upregulation of apolipoproteins-E and inhibition of Von Willebrand factor expression. In summary, MFRYR enriched in antioxidant and amino acid without monacolin-k showed similar hypocholesterolemic effect as CRYR that was rich in monacolin-k and GABA. PMID:25031606

Effect of yeast culture and Aspergillus oryzae fermentation extract on ruminal characteristics and nutrient digestibility.

PubMed

Wiedmeier, R D; Arambel, M J; Walters, J L

1987-10-01

Four nonpregnant and nonlactating Holstein cows fitted with ruminal fistulas were assigned to each of four diets in a 4 X 4 Latin square design. Dietary treatments were 1) basal diet containing 50% concentrate; 2) basal diet plus 90 g/d yeast culture; 3) basal diet plus 2.63 g/d Aspergillus oryzae fermentation extract; 4) basal diet plus 90 g/d of A. oryzae fermentation extract and yeast culture. Cows were fed diets at a rate of 86 g DM/kg BW.75 for 14 d adaptation followed by an 8-d collection period. Digestibility of dry matter was increased by A. oryzae and A. oryzae and yeast culture combination treatments. Digestibility of CP was increased regardless of fungal culture addition. Hemicellulose digestibility, percent ruminal cellulolytic organisms, and acetate to propionate ratio were increased by the addition of fungal supplements.

Optimization of the medium for Lactobacillus acidophilus by Plackett-Burman and steepest ascent experiment.

PubMed

Chen, He; Niu, Jinfeng; Qin, Tao; Ma, Qi; Wang, Lei; Shu, Guowei

2015-01-01

Lactobacillus acidophilus not only improves the intestinal flora balance but also inhabits the growth of undesirable microorganisms in intestine, which is benefit to the health of humans and animals. Plackett-Burman and steepest ascent experiment are the rapid and concise ways of screening the main effective factors. This study is aimed to select the main influence factors and optimize the medium for Lactobacillus acidophilus by Plackett-Burman experiment and steepest ascent experiment. The ideal carbon source was screened among glucose, maltose, lactose and whey powder, and the ideal nitrogen source was screened among casein hydrolysate, peptone, yeast extract powder, fish meal, carbamide, ammonium sulfate and sodium nitrate by single factor experiment. Plackett-Burman and steepest ascent experiment were applied to screen the main effective factors of Lactobacillus acidophilus among peptone, beef extract, yeast extract powder, glucose, K2HPO4, C6H14O7N2, CH3COONa, MgSO4 and Tween-80. Result. The results indicated that glucose (p = 0.01510) as negative factor and K2HPO4 (p = 0.02017) as positive effect were the significant growth factors of Lactobacillus acidophilus, CH3COONa (p = 0.09273) as positive effect was an important factor, and the optimized medium was as follows: glucose - 21 g/L, K2HPO4 - 3.5 g/L, CH3COONa - 6.5 g/L, peptone - 10 g/L, beef extract - 8 g/L, yeast extract pow. nd. Lactobacillus acidophilus not only improves the intestinal flora balance but also inhabits the growth of undesirable microorganisms in intestine, which is benefit to the health of humans and animals. Plackett-Burman and steepest ascent experiment are the rapid and concise ways of screening the main effective factors. This study is aimed to select the main influence factors and optimize the medium for Lactobacillus acidophilus by Plackett-Burman experiment and steepest ascent experiment. Material and methods. The ideal carbon source was screened among glucose, maltose, lactose and

Extraction of the number of peroxisomes in yeast cells by automated image analysis.

PubMed

Niemistö, Antti; Selinummi, Jyrki; Saleem, Ramsey; Shmulevich, Ilya; Aitchison, John; Yli-Harja, Olli

2006-01-01

An automated image analysis method for extracting the number of peroxisomes in yeast cells is presented. Two images of the cell population are required for the method: a bright field microscope image from which the yeast cells are detected and the respective fluorescent image from which the number of peroxisomes in each cell is found. The segmentation of the cells is based on clustering the local mean-variance space. The watershed transformation is thereafter employed to separate cells that are clustered together. The peroxisomes are detected by thresholding the fluorescent image. The method is tested with several images of a budding yeast Saccharomyces cerevisiae population, and the results are compared with manually obtained results.

The carbon consumption pattern of the spoilage yeast Brettanomyces bruxellensis in synthetic wine-like medium.

PubMed

Smith, Brendan D; Divol, Benoit

2018-08-01

The wine matrix contains limited carbon compounds to sustain microbial life. Brettanomyces bruxellensis is one of very few yeast species that has adapted to this environment. Indeed, the presence of growth-inhibiting compounds and conditions do not prevent its proliferation. Literature regarding the nutritional requirements of this yeast is surprisingly poor, given the observation that B. bruxellensis produces biomass with apparently less nutrients than other yeasts. In this study, various carbon sources were screened in a synthetic wine medium, under anaerobic and semi-aerobic growth conditions, in order to determine which compounds B. bruxellensis assimilates. Slight differences were observed between strains but overall, B. bruxellensis produced biomass from limited nutrients consumed in a specific order regardless of the oxygen conditions. Upon initial consumption of the simple sugars, B. bruxellensis was able to remain viable, by concurrently utilising ethanol (only in the presence of oxygen) and malic acid. Although initially beneficial, oxygen was found detrimental in the long term. Formation of volatile phenols occurred during the consumption of the sugars but not as a mechanism to help correct the redox imbalance. The study confirms that B. bruxellensis is able to survive using limited amount of nutrients, making this yeast a challenge for winemakers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Persistence of Pigment Production by Yeast Isolates Grown on CHROMagar Candida Medium

PubMed Central

Hospenthal, Duane R.; Murray, Clinton K.; Beckius, Miriam L.; Green, Judith A.; Dooley, David P.

2002-01-01

We evaluated the persistence of pigmentation in yeast isolates grown on the chromogenic medium CHROMagar Candida over 7 days. Candida, Cryptococcus, and Trichosporon isolates were inoculated alone or mixed onto duplicate sets of plates and incubated at 30 and 35°C. Candida albicans and Candida krusei were readily identified throughout the reading period, but Candida glabrata was difficult to differentiate from other species until the 3- or 4-day time point. Candida tropicalis produced colonies similar to those of rare Cryptococcus and Trichosporon species, and mixed cultures were often difficult to identify as such. PMID:12454192

Inhibition of human calcineurin and yeast calcineurin-dependent gene expression by Jasminum humile leaf and root extracts.

PubMed

Prescott, Thomas A K; Ariño, Joaquín; Kite, Geoffrey C; Simmonds, Monique S J

2012-03-27

The leaves of Jasminum humile are used to treat skin disorders in a way which resembles the use of modern topical anti-inflammatory drugs. Ethanolic extracts of the roots and leaves were shown to inhibit calcineurin which is a regulator of inflammatory gene expression. A novel yeast calcineurin reporter gene assay suitable for a 96 well plate format was developed to test for inhibition of calcineurin-dependent gene expression. Calmodulin/calcineurin phosphatase assays were then used to further elucidate the mode of action of the extracts. Jasminum humile root and leaf extract exhibited calcineurin inhibition activity that was shown to be mediated through a direct interaction with calcineurin enzyme. The activity is sufficient to block calcineurin-dependent gene expression in a yeast model. The activity of the plant supports its traditional use in the treatment of inflammatory skin disorders. The specially adapted yeast reporter assay was found to be a highly effective way of detecting calcineurin inhibitors in plant extracts. Crown Copyright © 2012. Published by Elsevier Ireland Ltd. All rights reserved.

Elicitation effect of Saccharomyces cerevisiae yeast extract on main health-promoting compounds and antioxidant and anti-inflammatory potential of butter lettuce (Lactuca sativa L.).

PubMed

Złotek, Urszula; Świeca, Michał

2016-05-01

This paper presents a study on changes in the main phytochemical levels and antioxidant and anti-inflammatory activity of lettuce caused by different doses and times of application of yeast extracts. Elicitation with yeast extract caused an increase in the total phenolic compounds and chlorophyll content, which varied according to the dose and time of spraying, but it did not have a positive impact on vitamin C, flavonoid and carotenoid content in lettuce. The best effect was achieved by double spraying with 1% yeast extract and by single spraying with 0.1% yeast extract. The increase in phytochemical content was positively correlated with the antioxidant and anti-inflammatory activity of the studied lettuce leaves. Chicoric acid seems to be the major contributor to these antioxidant activities. Yeast extract may be used as a natural, environmentally friendly and safe elicitor for improving the health-promoting qualities of lettuce. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Statistical optimization of culture medium for production of exopolysaccharide from endophytic fungus Bionectria ochroleuca and its antitumor effect in vitro

PubMed Central

Li, Yun; Guo, Shoujun; Zhu, Hui

2016-01-01

Endophytic fungi have been recognized as possible useful sources of bioactive metabolites. However, exopolysaccharide (EPS) production from endophytic fungi and its antitumor activity have been less explored. In the present study, endophtic fungus Bionectria ochroleuca M21 was exploited for the production of EPS in submerged culture. Among tested medium components, glucose, yeast extract, MgSO4 and Tween80 were found to be effective and significant on EPS production. Response surface methodology (RSM) was employed to optimize medium composition. The results showed that the significant factors were glucose, yeast extract and Tween80. The optimal medium was observed at the composition of glucose 55.7 g/L, yeast extract 6.04 g/L, MgSO4 0.25g/L and Tween80 0.1 % (v/v). Using the optimized medium, EPS production was achieve at 2.65 ± 0.16 g/L after 4 days fermentation in a 5L bioreactor. Examination of cytotoxicity showed that the EPS from B. ochroleuca M21 did not have cytotoxic activity on human liver HL-7702 cells at concentration 0.025-1.6 mg/mL. In contrast, the EPS exhibited antiproliferative activities against cell lines of liver cancer (HepG2), gastric cancer (SGC-7901) and colon cancer (HT29) in a dose- and time-dependent manner in the concentration ranges of 0.1-0.45 mg/mL. PMID:27330527

Unveiling the potential of novel yeast protein extracts in white wines clarification and stabilization

PubMed Central

Fernandes, Joana P.; Neto, Rodrigo; Centeno, Filipe; De Fátima Teixeira, Maria; Gomes, Ana Catarina

2015-01-01

Fining agents derived from animal and mineral sources are widely used to clarify and stabilize white wines. Nevertheless, health and environmental problems are being raised, concerning the allergenic and environmental impact of some of those fining products. In this study, our aim is to validate the potential of yeast protein extracts, obtained from an alternative and safe source, naturally present in wine: oenological yeasts. Three untreated white wines were used in this work in order to evaluate the impact of these novel yeast protein extracts (YPE) in terms of the wine clarification and stabilization improvement. Two separated fining trials were thus conducted at laboratory scale and the yeast alternatives were compared with reference fining agents, obtained from mineral, animal and vegetable origins. Our results indicate that YPE were capable to promote (i) brilliance/color improvement, (ii) turbidity reduction (76–89% comparing with the untreated wines), and (iii) production of compact and homogeneous lees (44% smaller volume than obtained with bentonite). Additionally, after submitting wines to natural and forced oxidations, YPE treatments revealed (iv) different forms of colloidal stabilization, by presenting comparable or superior effects when particularly compared to casein. Altogether, this study reveals that YPE represent a promising alternative for white wine fining, since they are resultant from a natural and more sustainable origin, at present not regarded as potential allergenic according to Regulation (EC) No. 1169/2011. PMID:25853122

The extraction of liquid, protein molecules and yeast cells from paper through surface acoustic wave atomization.

PubMed

Qi, Aisha; Yeo, Leslie; Friend, James; Ho, Jenny

2010-02-21

Paper has been proposed as an inexpensive and versatile carrier for microfluidics devices with abilities well beyond simple capillary action for pregnancy tests and the like. Unlike standard microfluidics devices, extracting a fluid from the paper is a challenge and a drawback to its broader use. Here, we extract fluid from narrow paper strips using surface acoustic wave (SAW) irradiation that subsequently atomizes the extracted fluid into a monodisperse aerosol for use in mass spectroscopy, medical diagnostics, and drug delivery applications. Two protein molecules, ovalbumin and bovine serum albumin (BSA), have been preserved in paper and then extracted using atomized mist through SAW excitation; protein electrophoresis shows there is less than 1% degradation of either protein molecule in this process. Finally, a solution of live yeast cells was infused into paper, which was subsequently dried for preservation then remoistened to extract the cells via SAW atomization, yielding live cells at the completion of the process. The successful preservation and extraction of fluids, proteins and yeast cells significantly expands the usefulness of paper in microfluidics.

Resinless section electron microscopy reveals the yeast cytoskeleton.

PubMed

Penman, J; Penman, S

1997-04-15

The cytoskeleton of Saccharomyces cerevisiae is essentially invisible using conventional microscopy techniques. A similar problem was solved for the mammalian cell cytoskeleton using resinless section electron microscopy, a technique applied here to yeast. In the resinless image, soluble proteins are no longer cloaked by embedding medium and must be removed by selective detergent extraction. In yeast, this requires breaching the cell wall by digesting with Zymolyase sufficiently to allow detergent extraction of the plasma membrane lipids. Gel electropherograms show that the extracted or "soluble" proteins are distinct from the retained or "structural" proteins that presumably comprise the cytoskeleton. These putative cytoskeleton proteins include the major portions of a 43-kDa protein, which is presumably actin, and of proteins in a band appearing at 55 kDa, as well as numerous less abundant, nonactin proteins. Resinless section electron micrographs show a dense, three-dimensional web of anastomosing, polymorphic filaments bounded by the remnant cell wall. Although the filament network is very heterogenous, there appear to be two principal classes of filament diameters-5 nm and 15-20 nm-which may correspond to actin and intermediate filaments, respectively. A large oval region of lower filament density probably corresponds to the vacuole, and an electron dense spheroidal body, 300-500 nm in diameter, is likely the nucleus. The techniques detailed in this report afford new approaches to the study of yeast cytoarchitecture.

Inaccurate DNA Synthesis in Cell Extracts of Yeast Producing Active Human DNA Polymerase Iota

PubMed Central

Makarova, Alena V.; Grabow, Corinn; Gening, Leonid V.; Tarantul, Vyacheslav Z.; Tahirov, Tahir H.; Bessho, Tadayoshi; Pavlov, Youri I.

2011-01-01

Mammalian Pol ι has an unusual combination of properties: it is stimulated by Mn2+ ions, can bypass some DNA lesions and misincorporates “G” opposite template “T” more frequently than incorporates the correct “A.” We recently proposed a method of detection of Pol ι activity in animal cell extracts, based on primer extension opposite the template T with a high concentration of only two nucleotides, dGTP and dATP (incorporation of “G” versus “A” method of Gening, abbreviated as “misGvA”). We provide unambiguous proof of the “misGvA” approach concept and extend the applicability of the method for the studies of variants of Pol ι in the yeast model system with different cation cofactors. We produced human Pol ι in baker's yeast, which do not have a POLI ortholog. The “misGvA” activity is absent in cell extracts containing an empty vector, or producing catalytically dead Pol ι, or Pol ι lacking exon 2, but is robust in the strain producing wild-type Pol ι or its catalytic core, or protein with the active center L62I mutant. The signature pattern of primer extension products resulting from inaccurate DNA synthesis by extracts of cells producing either Pol ι or human Pol η is different. The DNA sequence of the template is critical for the detection of the infidelity of DNA synthesis attributed to DNA Pol ι. The primer/template and composition of the exogenous DNA precursor pool can be adapted to monitor replication fidelity in cell extracts expressing various error-prone Pols or mutator variants of accurate Pols. Finally, we demonstrate that the mutation rates in yeast strains producing human DNA Pols ι and η are not elevated over the control strain, despite highly inaccurate DNA synthesis by their extracts. PMID:21304950

Inaccurate DNA synthesis in cell extracts of yeast producing active human DNA polymerase iota.

PubMed

Makarova, Alena V; Grabow, Corinn; Gening, Leonid V; Tarantul, Vyacheslav Z; Tahirov, Tahir H; Bessho, Tadayoshi; Pavlov, Youri I

2011-01-31

Mammalian Pol ι has an unusual combination of properties: it is stimulated by Mn(2+) ions, can bypass some DNA lesions and misincorporates "G" opposite template "T" more frequently than incorporates the correct "A." We recently proposed a method of detection of Pol ι activity in animal cell extracts, based on primer extension opposite the template T with a high concentration of only two nucleotides, dGTP and dATP (incorporation of "G" versus "A" method of Gening, abbreviated as "misGvA"). We provide unambiguous proof of the "misGvA" approach concept and extend the applicability of the method for the studies of variants of Pol ι in the yeast model system with different cation cofactors. We produced human Pol ι in baker's yeast, which do not have a POLI ortholog. The "misGvA" activity is absent in cell extracts containing an empty vector, or producing catalytically dead Pol ι, or Pol ι lacking exon 2, but is robust in the strain producing wild-type Pol ι or its catalytic core, or protein with the active center L62I mutant. The signature pattern of primer extension products resulting from inaccurate DNA synthesis by extracts of cells producing either Pol ι or human Pol η is different. The DNA sequence of the template is critical for the detection of the infidelity of DNA synthesis attributed to DNA Pol ι. The primer/template and composition of the exogenous DNA precursor pool can be adapted to monitor replication fidelity in cell extracts expressing various error-prone Pols or mutator variants of accurate Pols. Finally, we demonstrate that the mutation rates in yeast strains producing human DNA Pols ι and η are not elevated over the control strain, despite highly inaccurate DNA synthesis by their extracts.

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

PubMed

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

2017-04-01

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

Detergent assisted lipid extraction from wet yeast biomass for biodiesel: A response surface methodology approach.

PubMed

Yellapu, Sravan Kumar; Bezawada, Jyothi; Kaur, Rajwinder; Kuttiraja, Mathiazhakan; Tyagi, Rajeshwar D

2016-10-01

The lipid extraction from the microbial biomass is a tedious and high cost dependent process. In the present study, detergent assisted lipids extraction from the culture of the yeast Yarrowia lipolytica SKY-7 was carried out. Response surface methodology (RSM) was used to investigate the effect of three principle parameters (N-LS concentration, time and temperature) on microbial lipid extraction efficiency % (w/w). The results obtained by statistical analysis showed that the quadratic model fits in all cases. Maximum lipid recovery of 95.3±0.3% w/w was obtained at the optimum level of process variables [N-LS concentration 24.42mg (equal to 48mgN-LS/g dry biomass), treatment time 8.8min and reaction temperature 30.2°C]. Whereas the conventional chloroform and methanol extraction to achieve total lipid recovery required 12h at 60°C. The study confirmed that oleaginous yeast biomass treatment with N-lauroyl sarcosine would be a promising approach for industrial scale microbial lipid recovery. Copyright © 2016 Elsevier Ltd. All rights reserved.

A new pullulan-producing yeast and medium optimization for its exopolysaccharide production

NASA Astrophysics Data System (ADS)

Zhao, Shuangzhi; Chi, Zhenming

2003-04-01

Yeast strain Y68 producing high level of pullulan was isolated from the phyton collected in Toulouse, France. This strain was identified to be Rhodotorula bacarum by BIOLOG analysis. This is the first report that pullulan was produced by Rhodotorula bacarum. The optimal medium (g L-1) for pullulan production by this strain was 80 glucose, 20 soybean cake hydrolysate, 5 K2HPO4, 1 NaCl, 0.2 MgSO4·7H2O, 0.6 (NH4)2SO4, pH 7.0. Under this condition, 54 gL-1 pullulan was produced within 60 h at 30°C. Pullulan is a better starting material for producing marine prodrugs.

Acceleration of yoghurt fermentation time by yeast extract and partial characterisation of the active components.

PubMed

Smith, Esti-Andrine; Myburgh, Jacobus; Osthoff, Gernot; de Wit, Maryna

2014-11-01

Water soluble autolysate of yeast, usually utilised for microbial growth support, was used as additive in yoghurt fermentation. The yeast extract (YE) resulted in a decrease of fermentation time by 21% to reach a pH of 4·6. However, the YE resulted in unacceptable flavour and taste. By size exclusion chromatography, a fraction of the YE was obtained that could account for the observed 21% decrease in fermentation time. The fraction contained molecules of low molecular weight, consisting of minerals, free amino acids and peptides. The acceleration of the yoghurt fermentation was ascribed to the short peptides in the fraction. It is proposed that the application of this extract in industrial yoghurt manufacture would result in savings for both the industry and the consumer.

Malolactic bioconversion using a Oenococcus oeni strain for cider production: effect of yeast extract supplementation.

PubMed

Herrero, Mónica; García, Luis A; Díaz, Mario

2003-12-01

Yeast extract addition to reconstituted apple juice had a positive impact on the development of the malolactic starter culture used to ensure malolactic fermentation in cider, using active but non-proliferating cells. In this work, the reuse of fermentation lees from cider is proposed as an alternative to the use of commercial yeast extract products. Malolactic enzymatic assays, both in whole cells and cell-free extracts, were carried out to determine the best time to harvest cells for use as an inoculum in cider. Cells harvested at the late exponential phase, the physiological stage of growth corresponding to the maximum values of specific malolactic activity, achieved a good rate of malic acid degradation in controlled cider fermentation. Under the laboratory conditions used, malic acid degradation rates in the fermentation media turned out to be near 2.0 and 2.5 times lower, compared with the rates obtained in whole-cell enzymatic assays, as useful data applicable to industrial cider production.

A selective medium for recovery and enumeration of endolithic bacteria.

PubMed

Bhattacharjee, Kaushik; Joshi, S R

2016-10-01

The study of lithic microbial communities, inhabiting rock substrates has been gathering momentum due to a growing attention of their wide importance as model systems in ecological studies and for their community structure. It is generally accepted that the success of cultivation-based technique is primarily based on suitable culture medium for isolation. The media available for enumeration and recovery of endolithic bacteria are mainly specific to particular type of rock which may not be suitable to isolate endolithic bacterial community from diverse lithobiontic niches. In this study, a new unoptimized medium was formulated, designated LM10 (unoptimized) for enumeration and recovery of endolithic bacteria by addition and/or omission of media components to the basal medium R2G, which was selected after experimental evaluation of five different existing media. The endolithic bacterial count in LM10 medium (unoptimized) was significantly higher than the R2G medium (t=-12.57, p<0.0001). The culture and nutritional parameters associated with unoptimized LM10 medium were optimized using statistical approach to maximize the recovery and enumeration of endolithic bacteria. The first phase of the study comprised of a Plackett-Burman (PB) design experiment conducted to screen thirteen medium components and two culture parameters as variables with effect on bacterial enumeration and recovery. Out of these, Yeast extract, Casein hydrolysate, Glucose, Starch and Sodium thiosulphate were found to be significantly affecting the bacterial count (p<0.05) based on PB design. On keeping rest of the media components and culture conditions at fixed value as per the PB design analyses (p>0.05 and coefficients), further optimization was carried out for significant factors using Box-Behnken design (BBD) of response surface methodology (RSM). Optimized media components obtained by BBD were Yeast extract, Casein hydrolysate, Glucose and Starch in 0.05g/l each and Sodium thiosulphate in 0

Fractionation of yeast extract by nanofiltration process to assess key compounds involved in CHO cell culture improvement.

PubMed

Mosser, Mathilde; Kapel, Romain; Chevalot, Isabelle; Olmos, Eric; Marc, Ivan; Marc, Annie; Oriol, Eric

2015-01-01

Yeast extract (YE) is known to greatly enhance mammalian cell culture performances, but its undefined composition decreases process reliability. Accordingly, in the present study, the nature of YE compounds involved in the improvement of recombinant CHO cell growth and IgG production was investigated. First, the benefits of YE were verified, revealing that it increased maximal concentrations of viable cells and IgG up to 73 and 60%, respectively compared to a reference culture. Then, the analyses of YE composition highlighted the presence of molecules such as amino acids, vitamins, salts, nucleobase, and glucose that were contained in reference medium, while others including peptides, trehalose, polysaccharides, and nucleic acids were not. Consequently, YE was fractionated by a nanofiltration process to deeper evaluate its effects on CHO cell cultures. The YE molecules already contained in reference medium were mainly isolated in the permeate fraction together with trehalose and short peptides, while other molecules were concentrated in the retentate. Permeate, which was free of macromolecules, exhibited a similar positive effect than raw YE on maximal concentrations. Additional studies on cell energetic metabolism underlined that dipeptides and tripeptides in permeate were used as an efficient source of nitrogenous substrates. © 2015 American Institute of Chemical Engineers.

40 CFR 180.1246 - Yeast Extract Hydrolysate from Saccharomyces cerevisiae: exemption from the requirement of a...

Code of Federal Regulations, 2010 CFR

2010-07-01

... Hydrolysate from Saccharomyces cerevisiae on all food commodities when applied/used for the management of... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1246 Yeast Extract Hydrolysate from...

Screening of Ganoderma strains with high polysaccharides and ganoderic acid contents and optimization of the fermentation medium by statistical methods.

PubMed

Wei, Zhen-hua; Duan, Ying-yi; Qian, Yong-qing; Guo, Xiao-feng; Li, Yan-jun; Jin, Shi-he; Zhou, Zhong-Xin; Shan, Sheng-yan; Wang, Chun-ru; Chen, Xue-Jiao; Zheng, Yuguo; Zhong, Jian-Jiang

2014-09-01

Polysaccharides and ganoderic acids (GAs) are the major bioactive constituents of Ganoderma species. However, the commercialization of their production was limited by low yield in the submerged culture of Ganoderma despite improvement made in recent years. In this work, twelve Ganoderma strains were screened to efficiently produce polysaccharides and GAs, and Ganoderma lucidum 5.26 (GL 5.26) that had been never reported in fermentation process was found to be most efficient among the tested stains. Then, the fermentation medium was optimized for GL 5.26 by statistical method. Firstly, glucose and yeast extract were found to be the optimum carbon source and nitrogen source according to the single-factor tests. Ferric sulfate was found to have significant effect on GL 5.26 biomass production according to the results of Plackett-Burman design. The concentrations of glucose, yeast extract and ferric sulfate were further optimized by response surface methodology. The optimum medium composition was 55 g/L of glucose, 14 g/L of yeast extract, 0.3 g/L of ferric acid, with other medium components unchanged. The optimized medium was testified in the 10-L bioreactor, and the production of biomass, IPS, total GAs and GA-T enhanced by 85, 27, 49 and 93 %, respectively, compared to the initial medium. The fermentation process was scaled up to 300-L bioreactor; it showed good IPS (3.6 g/L) and GAs (670 mg/L) production. The biomass was 23.9 g/L in 300-L bioreactor, which was the highest biomass production in pilot scale. According to this study, the strain GL 5.26 showed good fermentation property by optimizing the medium. It might be a candidate industrial strain by further process optimization and scale-up study.

Measuring strand discontinuity-directed mismatch repair in yeast Saccharomyces cerevisiae by cell-free nuclear extracts.

PubMed

Yuan, Fenghua; Lai, Fangfang; Gu, Liya; Zhou, Wen; El Hokayem, Jimmy; Zhang, Yanbin

2009-05-01

Mismatch repair corrects biosynthetic errors generated during DNA replication, whose deficiency causes a mutator phenotype and directly underlies hereditary non-polyposis colorectal cancer and sporadic cancers. Because of remarkably high conservation of the mismatch repair machinery between the budding yeast (Saccharomyces cerevisiae) and humans, the study of mismatch repair in yeast has provided tremendous insights into the mechanisms of this repair pathway in humans. In addition, yeast cells possess an unbeatable advantage over human cells in terms of the easy genetic manipulation, the availability of whole genome deletion strains, and the relatively low cost for setting up the system. Although many components of eukaryotic mismatch repair have been identified, it remains unclear if additional factors, such as DNA helicase(s) and redundant nuclease(s) besides EXO1, participate in eukaryotic mismatch repair. To facilitate the discovery of novel mismatch repair factors, we developed a straightforward in vitro cell-free repair system. Here, we describe the practical protocols for preparation of yeast cell-free nuclear extracts and DNA mismatch substrates, and the in vitro mismatch repair assay. The validity of the cell-free system was confirmed by the mismatch repair deficient yeast strain (Deltamsh2) and the complementation assay with purified yeast MSH2-MSH6.

Extraction of In-Medium Nucleon-Nucleon Amplitude From Experiment

NASA Technical Reports Server (NTRS)

Tripathi, R. K.; Cucinotta, Francis A.; Wilson, John W.

1998-01-01

The in-medium nucleon-nucleon amplitudes are extracted from the available proton-nucleus total reaction cross sections data. The retrieval of the information from the experiment makes the estimate of reaction cross sections very reliable. Simple expressions are given for the in-medium nucleon-nucleon amplitudes for any system of colliding nuclei as a function of energy. Excellent agreement with experimental observations is demonstrated in the ion-nucleus interactions.

Identification of significant medium components that affect docosahexaenoic acid production by Schizochytrium sp. SW1

NASA Astrophysics Data System (ADS)

Manikan, Vidyah; Hamid, Aidil A.

2013-11-01

Central composite design (CCD) was employed to investigate the significance of glucose, yeast extract, MSG and sea salt in affecting the amount of docosahexaenoic acid (DHA) accumulated by a locally isolated strain of Schizochytrium. Design Expert software was used to construct a set of experiments where each medium component mentioned above was varied over three levels. Cultivation was carried out in 250mL flasks containing 50mL of medium, incubated at 30°C with 200 rpm agitation for 96 hours. ANOVA was conducted to identify the influential factors and the level of their significance where factors that scored a probability value of less than 0.05 were considered significant. The level of influence for each independent variable was also interpreted using perturbation whereas pattern of interaction between the factors were interpreted using interaction plots. This experiment revealed that yeast extract and monosodium glutamate have significant influence on DHA accumulation process by Schizochytrium sp. SW1.

Immunogenicity and protective efficacy of yeast extracts containing rotavirus-like particles: a potential veterinary vaccine.

PubMed

Rodríguez-Limas, William A; Pastor, Ana Ruth; Esquivel-Soto, Ernesto; Esquivel-Guadarrama, Fernando; Ramírez, Octavio T; Palomares, Laura A

2014-05-19

Rotavirus is the most common cause of severe diarrhea in many animal species of economic interest. A simple, safe and cost-effective vaccine is required for the control and prevention of rotavirus in animals. In this study, we evaluated the use of Saccharomyces cerevisiae extracts containing rotavirus-like particles (RLP) as a vaccine candidate in an adult mice model. Two doses of 1mg of yeast extract containing rotavirus proteins (between 0.3 and 3 μg) resulted in an immunological response capable of reducing the replication of rotavirus after infection. Viral shedding in all mice groups diminished in comparison with the control group when challenged with 100 50% diarrhea doses (DD50) of murine rotavirus strain EDIM. Interestingly, when immunizing intranasally protection against rotavirus infection was observed even when no increase in rotavirus-specific antibody titers was evident, suggesting that cellular responses were responsible of protection. Our results indicate that raw yeast extracts containing rotavirus proteins and RLP are a simple, cost-effective alternative for veterinary vaccines against rotavirus. Copyright © 2014 Elsevier Ltd. All rights reserved.

An original method for producing acetaldehyde and diacetyl by yeast fermentation.

PubMed

Rosca, Irina; Petrovici, Anca Roxana; Brebu, Mihai; Stoica, Irina; Minea, Bogdan; Marangoci, Narcisa

In this study a natural culture medium that mimics the synthetic yeast peptone glucose medium used for yeast fermentations was designed to screen and select yeasts capable of producing high levels of diacetyl and acetaldehyde. The presence of whey powder and sodium citrate in the medium along with manganese and magnesium sulfate enhanced both biomass and aroma development. A total of 52 yeasts strains were cultivated in two different culture media, namely, yeast peptone glucose medium and yeast acetaldehyde-diacetyl medium. The initial screening of the strains was based on the qualitative reaction of the acetaldehyde with Schiff's reagent (violet color) and diacetyl with Brady's reagent (yellow precipitate). The fermented culture media of 10 yeast strains were subsequently analyzed by gas chromatography to quantify the concentration of acetaldehyde and diacetyl synthesized. Total titratable acidity values indicated that a total titratable acidity of 5.5°SH, implying culture medium at basic pH, was more favorable for the acetaldehyde biosynthesis using strain D15 (Candida lipolytica; 96.05mgL -1 acetaldehyde) while a total titratable acidity value of 7°SH facilitated diacetyl flavor synthesis by strain D38 (Candida globosa; 3.58mgL -1 diacetyl). Importantly, the results presented here suggest that this can be potentially used in the baking industry. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Phenotyping the quality of complex medium components by simple online-monitored shake flask experiments.

PubMed

Diederichs, Sylvia; Korona, Anna; Staaden, Antje; Kroutil, Wolfgang; Honda, Kohsuke; Ohtake, Hisao; Büchs, Jochen

2014-11-07

Media containing yeast extracts and other complex raw materials are widely used for the cultivation of microorganisms. However, variations in the specific nutrient composition can occur, due to differences in the complex raw material ingredients and in the production of these components. These lot-to-lot variations can affect growth rate, product yield and product quality in laboratory investigations and biopharmaceutical production processes. In the FDA's Process Analytical Technology (PAT) initiative, the control and assessment of the quality of critical raw materials is one key aspect to maintain product quality and consistency. In this study, the Respiration Activity Monitoring System (RAMOS) was used to evaluate the impact of different yeast extracts and commercial complex auto-induction medium lots on metabolic activity and product yield of four recombinant Escherichia coli variants encoding different enzymes. Under non-induced conditions, the oxygen transfer rate (OTR) of E. coli was not affected by a variation of the supplemented yeast extract lot. The comparison of E. coli cultivations under induced conditions exhibited tremendous differences in OTR profiles and volumetric activity for all investigated yeast extract lots of different suppliers as well as lots of the same supplier independent of the E. coli variant. Cultivation in the commercial auto-induction medium lots revealed the same reproducible variations. In cultivations with parallel offline analysis, the highest volumetric activity was found at different cultivation times. Only by online monitoring of the cultures, a distinct cultivation phase (e.g. glycerol depletion) could be detected and chosen for comparable and reproducible offline analysis of the yield of functional product. This work proves that cultivations conducted in complex media may be prone to significant variation in final product quality and quantity if the quality of the raw material for medium preparation is not thoroughly

Evaluation of the Composition of Culture Medium for Yeast Biomass Production Using Raw Glycerol from Biodiesel Synthesis

PubMed Central

dos Santos, Elisane Odriosolla; Michelon, Mariano; Furlong, Eliana Badiale; Burkert, Janaína Fernandes de Medeiros; Kalil, Susana Juliano; Burkert, Carlos André Veiga

2012-01-01

The work herewith investigated the production of yeast biomass as a source of protein, using Yarrowia lipolytica NRRL YB-423 and raw glycerol from biodiesel synthesis as the main carbon source. A significant influence of glycerol concentration, initial pH and yeast extract concentration on biomass and protein content was observed according to the 2v5-1 fractional design. These factors were further evaluated using a central composite design and response surface methodology, and an empirical model for protein content was established and validated. The biomass of Yarrowia lipolytica NRRL YB-423 reached 19.5 ± 1.0 g/L in shaken flasks cultivation, with a protein content of 20.1 ± 0.6% (w/w). PMID:24031849

Influence of hen age on the response of turkey poults to cold stress, Escherichia coli challenge, and treatment with a yeast extract antibiotic alternative.

PubMed

Huff, G R; Huff, W E; Rath, N C; Solis de Los Santos, F; Farnell, M B; Donoghue, A M

2007-04-01

Two battery experiments were conducted to evaluate a commercial yeast extract feed supplement, Alphamune, in a cold stress-Escherichia coli challenge of 1-wk-old turkeys. Experiment 1 used 1-d-old male poults that were the progeny of 33-wk-old hens in their second week of lay. Experiment 2 used male poults of the same genetic line from 40-wk-old hens in their eighth week of lay. Poults were fed a standard unmedicated turkey starter diet or the same diet with either a low level (504 g/t) or a high level (1,008 g/t) of yeast extract. Challenged birds were exposed to intermittent cold stress during wk 1 to 3 and to a respiratory E. coli challenge at 1 wk of age. In both experiments, BW at wk 1 was increased by feeding yeast extract. In experiment 1, challenged, control-fed birds had decreased BW at wk 3 and feed conversion was protected by both levels of yeast extract supplementation. In experiment 2, challenge had no effect on control-fed birds; however, yeast extract decreased the BW of challenged birds. In experiment 1, total leukocyte numbers were decreased by challenge of control-fed birds only, and there was no effect of challenge on the heterophil/lymphocyte ratio. In experiment 2, total leukocyte numbers were decreased and the heterophil/lymphocyte ratio was increased in challenged, control-fed birds. Percentage mortality was not affected by challenge in experiment 1; however, in experiment 2, mortality was increased by challenge of control-fed birds and those fed the lower level of yeast extract. These results suggest that hen age should be considered when designing studies to evaluate antibiotic alternatives and in making decisions for incorporating such alternatives into production.

Discovery of plant extracts that greatly delay yeast chronological aging and have different effects on longevity-defining cellular processes

PubMed Central

Samson, Eugenie; Arlia-Ciommo, Anthony; Dakik, Pamela; Cortes, Berly; Feldman, Rachel; Mohtashami, Sadaf; McAuley, Mélissa; Chancharoen, Marisa; Rukundo, Belise; Simard, Éric; Titorenko, Vladimir I.

2016-01-01

We discovered six plant extracts that increase yeast chronological lifespan to a significantly greater extent than any of the presently known longevity-extending chemical compounds. One of these extracts is the most potent longevity-extending pharmacological intervention yet described. We show that each of the six plant extracts is a geroprotector which delays the onset and decreases the rate of yeast chronological aging by eliciting a hormetic stress response. We also show that each of these extracts has different effects on cellular processes that define longevity in organisms across phyla. These effects include the following: 1) increased mitochondrial respiration and membrane potential; 2) augmented or reduced concentrations of reactive oxygen species; 3) decreased oxidative damage to cellular proteins, membrane lipids, and mitochondrial and nuclear genomes; 4) enhanced cell resistance to oxidative and thermal stresses; and 5) accelerated degradation of neutral lipids deposited in lipid droplets. Our findings provide new insights into mechanisms through which chemicals extracted from certain plants can slow biological aging. PMID:26918729

The effect of yeast extract addition on quality of fermented sausages at low NaCl content.

PubMed

Campagnol, Paulo Cezar Bastianello; dos Santos, Bibiana Alves; Wagner, Roger; Terra, Nelcindo Nascimento; Pollonio, Marise Aparecida Rodrigues

2011-03-01

Fermented sausages with 25% or 50% of their NaCl replaced by KCl and supplemented with 1% or 2% concentrations of yeast extract were produced. The sausage production process was monitored with physical, chemical and microbiological analyses. After production, the sausage samples were submitted to a consumer study and their volatile compounds were extracted by solid-phase microextraction and analyzed by GC-MS. The replacement of NaCl by KCl did not significantly influence the physical, chemical or microbiological characteristics. The sensory quality of the fermented sausages with a 50% replacement was poor compared with the full-salt control samples. The use of yeast extract at a 2% concentration increased volatile compounds that arose from amino acids and carbohydrate catabolism. These compounds contributed to the suppression of the sensory-quality defects caused by the KCl introduction, thus enabling the production of safe fermented sausages that have acceptable sensory qualities with half as much sodium content. Copyright © 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.

Actinobacillus succinogenes ATCC 55618 Fermentation Medium Optimization for the Production of Succinic Acid by Response Surface Methodology

PubMed Central

Zhu, Li-Wen; Wang, Cheng-Cheng; Liu, Rui-Sang; Li, Hong-Mei; Wan, Duan-Ji; Tang, Ya-Jie

2012-01-01

As a potential intermediary feedstock, succinic acid takes an important place in bulk chemical productions. For the first time, a method combining Plackett-Burman design (PBD), steepest ascent method (SA), and Box-Behnken design (BBD) was developed to optimize Actinobacillus succinogenes ATCC 55618 fermentation medium. First, glucose, yeast extract, and MgCO3 were identified to be key medium components by PBD. Second, preliminary optimization was run by SA method to access the optimal region of the key medium components. Finally, the responses, that is, the production of succinic acid, were optimized simultaneously by using BBD, and the optimal concentration was located to be 84.6 g L−1 of glucose, 14.5 g L−1 of yeast extract, and 64.7 g L−1 of MgCO3. Verification experiment indicated that the maximal succinic acid production of 52.7 ± 0.8 g L−1 was obtained under the identified optimal conditions. The result agreed with the predicted value well. Compared with that of the basic medium, the production of succinic acid and yield of succinic acid against glucose were enhanced by 67.3% and 111.1%, respectively. The results obtained in this study may be useful for the industrial commercial production of succinic acid. PMID:23093852

Interaction of fructose with other medium components to affect bioproduction of docosahexaenoic acid (DHA) by Aurantiochytrium sp. SW1

NASA Astrophysics Data System (ADS)

Manikan, Vidyah; Kalil, Mohd. Sahaid; Shuib, Shuwahida; Hamid, Aidil Abdul

2018-04-01

Thraustochytrids are a group of marine fungus-like microheterotrophs of which some can accumulate considerable amounts of the high valued omega-3 oil, docosahexaenoic acid (DHA). In this study, a local thraustochytrid isolate, Aurantiochytrium sp. SW1, was cultivated in a medium containing fructose as the major carbon source. The effects of this carbon source in interaction with yeast extract, monosodium glutamate (MSG) and sea salt were studied using a software-based two level full factorial design. Results showed that fructose as a single factor, has significant positive effect on the volumetric DHA content of SW1. Similarly, its interaction with yeast extract has profound positive effect. However, interactions of fructose with MSG and sea salt were significant negative effects. These results indicate that manipulation of the concentration of fructose in the culture medium may serve as a simple and useful strategy to help achieve preferred amount of DHA.

Comparison of culture media for the recovery of airborne yeast in wineries.

PubMed

Ocón, E; Garijo, P; Santamaría, P; López, R; Olarte, C; Gutiérrez, A R; Sanz, S

2013-09-01

The direct air sampling impaction method on agar was evaluated using aerobiocollectors for the recovery of yeasts present in the winery air. Three culture media with different composition and specificity were studied. In addition, a resuscitation phase was included before the culture in the specificity medium [in the case of the Dekkera-Brettanomyces Differential Medium (DBDM) medium]. Sampling was conducted at different times of the year and in different parts of the wineries, which were different in age and design. Both the Chloramphenicol Glucose Agar (CGA) and Agar Lysine AL media recovered yeasts from the air without any prior resuscitation phase. CGA was able to recover a higher number of colony-forming units of yeasts than the other media. Consequently, to estimate the number of yeasts present in winery air, the best choice of medium would be CGA. The AL medium permitted the growth of the greatest range of genera and species. If the aim is to study the diversity of yeasts present in the air, the most suitable medium is AL. Neither CGA nor AL proved suitable for recovering yeasts of the Brettanomyces genus. The DBDM medium was the only one which provided sufficient specificity for their recovery and identification from the air, although their special characteristics made a prior protocol of resuscitation necessary. © 2013 The Society for Applied Microbiology.

Response surface optimization of culture medium for enhanced docosahexaenoic acid production by a Malaysian thraustochytrid.

PubMed

Manikan, Vidyah; Kalil, Mohd Sahaid; Hamid, Aidil Abdul

2015-02-27

Docosahexaenoic acid (DHA, C22:6n-3) plays a vital role in the enhancement of human health, particularly for cognitive, neurological, and visual functions. Marine microalgae, such as members of the genus Aurantiochytrium, are rich in DHA and represent a promising source of omega-3 fatty acids. In this study, levels of glucose, yeast extract, sodium glutamate and sea salt were optimized for enhanced lipid and DHA production by a Malaysian isolate of thraustochytrid, Aurantiochytrium sp. SW1, using response surface methodology (RSM). The optimized medium contained 60 g/L glucose, 2 g/L yeast extract, 24 g/L sodium glutamate and 6 g/L sea salt. This combination produced 17.8 g/L biomass containing 53.9% lipid (9.6 g/L) which contained 44.07% DHA (4.23 g/L). The optimized medium was used in a scale-up run, where a 5 L bench-top bioreactor was employed to verify the applicability of the medium at larger scale. This produced 24.46 g/L biomass containing 38.43% lipid (9.4 g/L), of which 47.87% was DHA (4.5 g/L). The total amount of DHA produced was 25% higher than that produced in the original medium prior to optimization. This result suggests that Aurantiochytrium sp. SW1 could be developed for industrial application as a commercial DHA-producing microorganism.

Extraction of brewer's yeasts using different methods of cell disruption for practical biodiesel production.

PubMed

Řezanka, Tomáš; Matoulková, Dagmar; Kolouchová, Irena; Masák, Jan; Viden, Ivan; Sigler, Karel

2015-05-01

The methods of preparation of fatty acids from brewer's yeast and its use in production of biofuels and in different branches of industry are described. Isolation of fatty acids from cell lipids includes cell disintegration (e.g., with liquid nitrogen, KOH, NaOH, petroleum ether, nitrogenous basic compounds, etc.) and subsequent processing of extracted lipids, including analysis of fatty acid and computing of biodiesel properties such as viscosity, density, cloud point, and cetane number. Methyl esters obtained from brewer's waste yeast are well suited for the production of biodiesel. All 49 samples (7 breweries and 7 methods) meet the requirements for biodiesel quality in both the composition of fatty acids and the properties of the biofuel required by the US and EU standards.

Effect of jasmonic acid and yeast extract elicitation on low-molecular antioxidants and antioxidant activity of marjoram (Origanum majorana L.).

PubMed

Złotek, Urszula

2017-01-01

Elicitation, which is a way of inducing plant secondary metabolism, may be an effective method for improving the quality of plant food. The aim of this study was to determine how the application of jasmonic acid (as an abiotic elicitor) and yeast extract (as a biotic elicitor) influences the production of some bioactive compounds in marjoram and the antioxidant activity of this herb. Elicitation with 0.01 µM and 1 µM jasmonic acid as well as 0.1% and 1% yeast extracts was used for improving the health-benefiting quality of marjoram. The study focused on the effects of eliciting the level of some phytochemicals and the antioxidant activity of marjoram. There were no significant differences in total phenolic content between the elicited and control plants. In turn, the elicitation with 0.1% and 1% yeast extracts caused 1.8- and 2.5-fold increases in the ascorbic acid content in marjoram leaves, respectively. Both biotic and abiotic elicitation resulted in elevation of chlorophyll content, but only the abiotic elicitor (jasmonic acid) caused a significant increase (by over 50%) in the carotenoid content of marjoram leaves. The antiradical activity of marjoram was increased by the abiotic and biotic elicitation, whereas only the abiotic elicitation resulted in improving the reducing power of this herb. In conclusion, biotic and abiotic elicitation could be an effective strategy for improving the level of some phytochemicals, as well as the antioxidant activity of marjoram. A particularly valuable finding obtained in this study is that natural elicitors e.g. yeast extract can be equally effective in elevating the content of some bioactive compounds in herbs e.g. marjoram as an abiotic one.

A new model for simulating microbial cyanide production and optimizing the medium parameters for recovering precious metals from waste printed circuit boards.

PubMed

Yuan, Zhihui; Ruan, Jujun; Li, Yaying; Qiu, Rongliang

2018-04-10

Bioleaching is a green recycling technology for recovering precious metals from waste printed circuit boards (WPCBs). However, this technology requires increasing cyanide production to obtain desirable recovery efficiency. Luria-Bertani medium (LB medium, containing tryptone 10 g/L, yeast extract 5 g/L, NaCl 10 g/L) was commonly used in bioleaching of precious metal. In this study, results showed that LB medium did not produce highest yield of cyanide. Under optimal culture conditions (25 °C, pH 7.5), the maximum cyanide yield of the optimized medium (containing tryptone 6 g/L and yeast extract 5 g/L) was 1.5 times as high as that of LB medium. In addition, kinetics and relationship of cell growth and cyanide production was studied. Data of cell growth fitted logistics model well. Allometric model was demonstrated effective in describing relationship between cell growth and cyanide production. By inserting logistics equation into allometric equation, we got a novel hybrid equation containing five parameters. Kinetic data for cyanide production were well fitted to the new model. Model parameters reflected both cell growth and cyanide production process. Copyright © 2018 Elsevier B.V. All rights reserved.

Production and Its Anti-hyperglycemic Effects of γ-Aminobutyric Acid from the Wild Yeast Strain Pichia silvicola UL6-1 and Sporobolomyces carnicolor 402-JB-1.

PubMed

Han, Sang-Min; Lee, Jong-Soo

2017-09-01

This study was done to produce γ-aminobutyric acid (GABA) from wild yeast as well as investigate its anti-hyperglycemic effects. Among ten GABA-producing yeast strains, Pichia silvicola UL6-1 and Sporobolomyces carnicolor 402-JB-1 produced high GABA concentration of 134.4 µg/mL and 179.2 µg/mL, respectively. P. silvicola UL6-1 showed a maximum GABA yield of 136.5 µg/mL and 200.8 µg/mL from S. carnicolor 402-JB-1 when they were cultured for 30 hr at 30℃ in yeast extract-peptone-dextrose medium. The cell-free extract from P. silvicola UL6-1 and S. carnicolor 402-JB-1 showed very high anti-hyperglycemic α-glucosidase inhibitory activity of 72.3% and 69.9%, respectively. Additionally, their cell-free extract-containing GABA showed the anti-hyperglycemic effect in streptozotocin-induced diabetic Sprague-Dawley rats.

Phenylalanine ammonia-lyase. Induction and purification from yeast and clearance in mammals.

PubMed

Fritz, R R; Hodgins, D S; Abell, C W

1976-08-10

Yeast phenylalanine ammonia-lyase (EC 4.3.1.5) catalyzes the deamination of L-phenylalanine to form trans-cinnamic acid and tyrosine to trans-coumaric acid. Maximal enzyme activity in Rhodotorula glutinis (2 units/g, wet weight, of yeast) was induced in late-log phase (12 to 14 hours) of growth in a culture medium containing 1.0% malt extract, 0.1% yeast extract, and 0.1% L-phenylalanine. A highly purified enzyme was obtained by fractionation with ammonium sulfate and sodium citrate followed by chromatography on DEAE-cellulose and Sephadex G-200. The active preparation yielded a major component on three different polyacrylamide gel electrophoretic systems. Antisera to phenylalanine ammonia-lyase was raised in rabbits and detected by double immunodiffusion. The antigen-antibody complex was enzymatically active in vitro. The biological half-life of the enzyme was approximately 21 hours in several mammalian species (mice without and with BW10232 adenocarcinoma and B16 melanoma, rats, and monkeys) after a single injection; however, upon repeated administration, phenylalanine ammonia-lyase had a much shorter biological half-life. The onset of rapid clearance occurred earlier in tumor-bearing than in nontumor-bearing mice indicating a direct or indirect influence by the tumor on the biological half-life of phenylalanine ammonia-lyase.

Response surface optimization of culture medium for enhanced docosahexaenoic acid production by a Malaysian thraustochytrid

PubMed Central

Manikan, Vidyah; Kalil, Mohd Sahaid; Hamid, Aidil Abdul

2015-01-01

Docosahexaenoic acid (DHA, C22:6n-3) plays a vital role in the enhancement of human health, particularly for cognitive, neurological, and visual functions. Marine microalgae, such as members of the genus Aurantiochytrium, are rich in DHA and represent a promising source of omega-3 fatty acids. In this study, levels of glucose, yeast extract, sodium glutamate and sea salt were optimized for enhanced lipid and DHA production by a Malaysian isolate of thraustochytrid, Aurantiochytrium sp. SW1, using response surface methodology (RSM). The optimized medium contained 60 g/L glucose, 2 g/L yeast extract, 24 g/L sodium glutamate and 6 g/L sea salt. This combination produced 17.8 g/L biomass containing 53.9% lipid (9.6 g/L) which contained 44.07% DHA (4.23 g/L). The optimized medium was used in a scale-up run, where a 5 L bench-top bioreactor was employed to verify the applicability of the medium at larger scale. This produced 24.46 g/L biomass containing 38.43% lipid (9.4 g/L), of which 47.87% was DHA (4.5 g/L). The total amount of DHA produced was 25% higher than that produced in the original medium prior to optimization. This result suggests that Aurantiochytrium sp. SW1 could be developed for industrial application as a commercial DHA-producing microorganism. PMID:25721623

Rice bran extract: an inexpensive nitrogen source for the production of 2G ethanol from sugarcane bagasse hydrolysate.

PubMed

Milessi, Thais S S; Antunes, Felipe A F; Chandel, Anuj K; Silva, Silvio S

2013-10-01

Selection of the raw material and its efficient utilization are the critical factors in economization of second generation (2G) ethanol production. Fermentation of the released sugars into ethanol by a suitable ethanol producing microorganism using cheap media ingredients is the cornerstone of the overall process. This study evaluated the potential of rice bran extract (RBE) as a cheap nitrogen source for the production of 2G ethanol by Scheffersomyces (Pichia) stipitis NRRL Y-7124 using sugarcane bagasse (SB) hemicellulosic hydrolysate. Dilute acid hydrolysis of SB showed 12.45 g/l of xylose and 0.67 g/l of glucose along with inhibitors. It was concentrated by vacuum evaporation and submitted to sequential detoxification (neutralization by calcium hydroxide and charcoal adsorption). The detoxified hydrolysate revealed the removal of furfural (81 %) and 5-hydroxymethylfurfural (61 %) leading to the final concentration of glucose (1.69 g/l) and xylose (33.03 g/l). S. stipitis was grown in three different fermentation media composed of detoxified hydrolysate as carbon source supplemented with varying nitrogen sources i.e. medium #1 (RBE + ammonium sulfate + calcium chloride), medium #2 (yeast extract + peptone) and medium #3 (yeast extract + peptone + malt extract). Medium #1 showed maximum ethanol production (8.6 g/l, yield 0.22 g/g) followed by medium #2 (8.1 g/l, yield 0.19 g/g) and medium #3 (7.4 g/l, yield 0.18 g/g).

Enhanced Bio-Ethanol Production from Industrial Potato Waste by Statistical Medium Optimization

PubMed Central

Izmirlioglu, Gulten; Demirci, Ali

2015-01-01

Industrial wastes are of great interest as a substrate in production of value-added products to reduce cost, while managing the waste economically and environmentally. Bio-ethanol production from industrial wastes has gained attention because of its abundance, availability, and rich carbon and nitrogen content. In this study, industrial potato waste was used as a carbon source and a medium was optimized for ethanol production by using statistical designs. The effect of various medium components on ethanol production was evaluated. Yeast extract, malt extract, and MgSO4·7H2O showed significantly positive effects, whereas KH2PO4 and CaCl2·2H2O had a significantly negative effect (p-value < 0.05). Using response surface methodology, a medium consisting of 40.4 g/L (dry basis) industrial waste potato, 50 g/L malt extract, and 4.84 g/L MgSO4·7H2O was found optimal and yielded 24.6 g/L ethanol at 30 °C, 150 rpm, and 48 h of fermentation. In conclusion, this study demonstrated that industrial potato waste can be used effectively to enhance bioethanol production. PMID:26501261

Enhanced Bio-Ethanol Production from Industrial Potato Waste by Statistical Medium Optimization.

PubMed

Izmirlioglu, Gulten; Demirci, Ali

2015-10-15

Industrial wastes are of great interest as a substrate in production of value-added products to reduce cost, while managing the waste economically and environmentally. Bio-ethanol production from industrial wastes has gained attention because of its abundance, availability, and rich carbon and nitrogen content. In this study, industrial potato waste was used as a carbon source and a medium was optimized for ethanol production by using statistical designs. The effect of various medium components on ethanol production was evaluated. Yeast extract, malt extract, and MgSO₄·7H₂O showed significantly positive effects, whereas KH₂PO₄ and CaCl₂·2H₂O had a significantly negative effect (p-value<0.05). Using response surface methodology, a medium consisting of 40.4 g/L (dry basis) industrial waste potato, 50 g/L malt extract, and 4.84 g/L MgSO₄·7H₂O was found optimal and yielded 24.6 g/L ethanol at 30 °C, 150 rpm, and 48 h of fermentation. In conclusion, this study demonstrated that industrial potato waste can be used effectively to enhance bioethanol production.

Ammonium is a key determinant on the dietary restriction of yeast chronological aging in culture medium

PubMed Central

Santos, Júlia; Leitão-Correia, Fernanda

2015-01-01

New evidences have recently emerged from studies in yeast and in higher eukaryotes showing the importance of nutrient balance in dietary regimes and its effects on longevity regulation. We have previously shown that manipulation ofammoniumconcentration in the culture and/or aging medium can drastically affect chronological lifespan (CLS) of Saccharomyces cerevisiae, especially in amino acid restricted cells. Here we describe that the CLS shortening under amino acid restriction can be completely reverted by removing ammonium from the culture medium. Furthermore, the absence of ammonium, and of any rich nitrogen source, was so effective in extending CLS that no beneficial effect could be observed by further imposing calorie restriction conditions. When present in the culture medium,ammoniumimpaired the consumption of theauxotrophy-complementing amino acidsand caused in an improper cell cycle arrest of the culture. TOR1 deletion reverted ammonium effects both in amino acid restricted and non-restricted cultures, whereas, Ras2p and Sch9p seem to have only a milder effect in the mediation ofammonium toxicity under amino acid restriction and no effect on non-restricted cultures. Our studies highlight ammonium as a key effector in the nutritional equilibrium between rich and essential nitrogen sources and glucose required for longevity promotion. PMID:25576917

Production and Its Anti-hyperglycemic Effects of γ-Aminobutyric Acid from the Wild Yeast Strain Pichia silvicola UL6-1 and Sporobolomyces carnicolor 402-JB-1

PubMed Central

Han, Sang-Min

2017-01-01

This study was done to produce γ-aminobutyric acid (GABA) from wild yeast as well as investigate its anti-hyperglycemic effects. Among ten GABA-producing yeast strains, Pichia silvicola UL6-1 and Sporobolomyces carnicolor 402-JB-1 produced high GABA concentration of 134.4 µg/mL and 179.2 µg/mL, respectively. P. silvicola UL6-1 showed a maximum GABA yield of 136.5 µg/mL and 200.8 µg/mL from S. carnicolor 402-JB-1 when they were cultured for 30 hr at 30℃ in yeast extract-peptone-dextrose medium. The cell-free extract from P. silvicola UL6-1 and S. carnicolor 402-JB-1 showed very high anti-hyperglycemic α-glucosidase inhibitory activity of 72.3% and 69.9%, respectively. Additionally, their cell-free extract-containing GABA showed the anti-hyperglycemic effect in streptozotocin-induced diabetic Sprague-Dawley rats. PMID:29138625

Influence of Selenium Content in the Culture Medium on Protein Profile of Yeast Cells Candida utilis ATCC 9950

PubMed Central

Kieliszek, Marek; Błażejak, Stanisław; Bzducha-Wróbel, Anna

2015-01-01

Selenium is an essential trace element for human health and it has been recognized as a component of several selenoproteins with crucial biological functions. It has been identified as a component of active centers of many enzymes, as well as integral part of biologically active complexes. The aim of the study was to evaluate the protein content and amino acid profile of the protein of fodder yeast Candida utilis ATCC 9950 cultured in media control and experimental enriched selenium. Protein analysis was performed using SDS-PAGE method consisting of polyacrylamide gel electrophoresis in the presence of SDS. The highest contents of soluble protein (49,5 mg/g) were found in yeast cells after 24-hour culture conducted in control (YPD) medium. In the presence of selenium there were determined small amounts of protein content. With increasing time of yeast culture (to 72 hours) the control and experimental media were reported to reduce soluble protein content. In electropherogram proteins from control cultures was observed the presence of 10 protein fractions, but in all the experimental cultures (containing 20, 30, and 40 mg/L selenium) of 14 protein fractions. On the basis of the molecular weights of proteins, it can be concluded that they were among others: selenoprotein 15 kDa and selenoprotein 18 kDa. PMID:26185592

Evaluation and optimization of ethanol production from carob pod extract by Zymomonas mobilis using response surface methodology.

PubMed

Vaheed, Hossein; Shojaosadati, Seyed Abbas; Galip, Hasan

2011-01-01

In this research, ethanol production from carob pod extract (extract) using Zymomonas mobilis with medium optimized by Plackett-Burman (P-B) and response surface methodologies (RSM) was studied. Z. mobilis was recognized as useful for ethanol production from carob pod extract. The effects of initial concentrations of sugar, peptone, and yeast extract as well as agitation rate (rpm), pH, and culture time in nonhydrolyzed carob pod extract were investigated. Significantly affecting variables (P = 0.05) in the model obtained from RSM studies were: weights of bacterial inoculum, initial sugar, peptone, and yeast extract. Acid hydrolysis was useful to complete conversion of sugars to glucose and fructose. Nonhydrolyzed extract showed higher ethanol yield and residual sugar compared with hydrolyzed extract. Ethanol produced (g g(-1) initial sugar, as the response) was not significantly different (P = 0.05) when Z. mobilis performance was compared in hydrolyzed and nonhydrolyzed extract. The maximum ethanol of 0.34 ± 0.02 g g(-1) initial sugar was obtained at 30°C, initial pH 5.2, and 80 rpm, using concentrations (g per 50 mL culture media) of: inoculum bacterial dry weight, 0.017; initial sugar, 5.78; peptone, 0.43; yeast extract, 0.43; and culture time of 36 h.

Secretion of non-cell-bound phytase by the yeast Pichia kudriavzevii TY13.

PubMed

Hellström, A; Qvirist, L; Svanberg, U; Veide Vilg, J; Andlid, T

2015-05-01

Mineral deficiencies cause several health problems in the world, especially for populations consuming cereal-based diets rich in the anti-nutrient phytate. Our aim was to characterize the phytate-degrading capacity of the yeast Pichia kudriavzevii TY13 and its secretion of phytase. The phytase activity in cell-free supernatants from cultures with 100% intact cells was 35-190 mU ml(-1) depending on the media. The Km was 0.28 mmol l(-1) and the specific phytase activity 0.32 U mg(-1) total protein. The phytase activity and secretion of extracellular non-cell-bound phytase was affected by the medium phosphate concentrations. Further, addition of yeast extract had a clearly inducing effect, resulting in over 60% of the cultures total phytase activity as non-cell-bound. Our study reveals that it is possible to achieve high extracellular phytase activity from the yeast P. kudriavzevii TY13 by proper composition of the growth medium. TY13 could be a promising future starter culture for fermented foods with improved mineral bioavailability. Using strains that secrete phytase to the food matrix may significantly improve the phytate degradation by facilitating the enzyme-to-substrate interaction. The secreted non-cell-bound phytase activities by TY13 could further be advantageous in industrial production of phytase. © 2015 The Society for Applied Microbiology.

A newly anti-Streptococcus suis bacteriocin producing strain from unweaned piglets fecal matter: isolation, preliminary identification, and optimization of medium composition for enhanced bacteriocin production.

PubMed

Zhang, Xiangmei; Chang, Xiaoyuan; Liu, Guorong; Wu, Pengpeng; Li, Pinglan

2012-01-01

A newly isolated anti-Streptococcus suis bacteriocin-producing strain LPL1-5 was obtained from healthy unweaned piglets' fecal matter, and was designated as Lactobacillus pentosus LPL1-5 based on morphology, biochemical properties, and 16S rDNA sequencing analysis. The medium composition for enhanced bacteriocin production by L. pentosus LPL1-5 was optimized by statistical methodology. Yeast extract, K(2)HPO(4)·3H(2)O, and MnSO(4)·H(2)O were identified as significant components influencing pentocin LPL1-5 production using the Plackett-Burman method. Response surface methodology was applied for further optimization. The concentrations of medium components for enhanced pentocin LPL1-5 production were as follows (g/L): lactose 20.00, tryptone 10.00, beef extract 10.00, yeast extract 14.00, MnSO(4)·H(2)O 0.84, K(2)HPO(4)·3H(2)O 4.92, triammonium citrate 2.00, Na-acetate 5.00, MgSO(4)·7H(2)O 0.58, Tween 80 1.00. Under the optimized condition, a value of 3154.65 ± 27.93 IU/mL bacteriocin activity was achieved, which was 4.2-fold that of the original medium.

Effect of Medium pH on Rhodosporidium toruloides NCYC 921 Carotenoid and Lipid Production Evaluated by Flow Cytometry.

PubMed

Dias, Carla; Silva, Corália; Freitas, Claudia; Reis, Alberto; da Silva, Teresa Lopes

2016-07-01

The effect of the culture medium pH (3.5-6.0) on the carotenoid and lipid (as fatty acids) production by the yeast Rhodosporidium toruloides NCYC 921 was studied. Flow cytometry was used to evaluate the yeast's physiological response to different culture medium pH values. The yeast biomass concentration and lipid content were maxima at pH 4.0 (5.90 g/L and 21.85 % w/w, respectively), while the maximum carotenoid content (63.37 μg/g) was obtained at pH 5.0. At the exponential phase, the yeast cell size and internal complexity were similar, at different medium pH. At the stationary phase, the yeast cell size and internal complexity decreased as the medium pH increased. At the exponential phase, the proportion of cells with polarized membranes was always high (>80 %) but at the stationary phase, the proportion of yeast cells with depolarized membranes was dominant (>65 %) and increased with the medium pH increase. The results here reported may contribute for yeast bioprocesses optimization. For the first time, multiparameter flow cytometry was used to evaluate the impact of medium pH changes on the yeast cell physiological status, specifically on the yeast membrane potential, membrane integrity, cell size and internal complexity.

Distinct Kynureninase and Hydroxykynureninase Activities in Microorganisms: Occurrence and Properties of a Single Physiologically Discrete Enzyme in Yeast

PubMed Central

Shetty, A. S.; Gaertner, F. H.

1973-01-01

(i) Saccharomyces cerevisiae grown in the presence of 1.0 mM l-tryptophan slowly excreted fluorescent material that was chromatographically identifiable as 3-hydroxyanthranilate but did not excrete detectable amounts of anthranilate nor rapidly deplete the medium of l-tryptophan. Under similar growth conditions, Neurospora crassa rapidly excretes anthranilate and rapidly depletes the medium of l-tryptophan. (ii) Chromatographic analysis of crude extracts from yeast revealed a single kynureninase-type enzyme whose synthesis was not measurably affected by the presence of tryptophan in the medium. Previous studies have provided evidence for two kynureninase-type enzymes in N. crassa, an inducible kynureninase and a constitutive hydroxykynureninase. (iii) Kinetic analysis of the partially purified yeast enzyme provided Michaelis constants for l-3-hydroxykynurenine and l-kynurenine of 6.7 × 10−6 and 5.4 × 10−4 M, respectively. This and other kinetic properties of the yeast enzyme are comparable to those reported for the constitutive enzyme from N. crassa. (iv) These findings suggest that S. cerevisiae has in common with N. crassa the biosynthetic enzyme hydroxykynureninase but lacks the catabolic enzyme kynureninase. Therefore, it can be predicted that, unlike N. crassa, S. cerevisiae does not carry out the tryptophan-anthranilate cycle. Distinct kynureninase-type enzymes may exist in other microorganisms and in mammals. PMID:4266242

Nutrient supplements boost yeast transformation efficiency

PubMed Central

Yu, Sheng-Chun; Dawson, Alexander; Henderson, Alyssa C.; Lockyer, Eloise J.; Read, Emily; Sritharan, Gayathri; Ryan, Marjah; Sgroi, Mara; Ngou, Pok M.; Woodruff, Rosie; Zhang, Ruifeng; Ren Teen Chia, Travis; Liu, Yu; Xiang, Yiyu; Spanu, Pietro D.

2016-01-01

Efficiency of yeast transformation is determined by the rate of yeast endocytosis. The aim of this study was to investigate the effect of introducing amino acids and other nutrients (inositol, adenine, or p-aminobenzoic acid) in the transformation medium to develop a highly efficient yeast transformation protocol. The target of rapamycin complex 1 (TORC1) kinase signalling complex influences the rate of yeast endocytosis. TORC signaling is induced by amino acids in the media. Here, we found that increasing the concentration of amino acids and other nutrients in the growth media lead to an increase yeast transformation efficiency up to 107 CFU per μg plasmid DNA and per 108 cells with a 13.8 kb plasmid DNA. This is over 130 times that of current published methods. This improvement may facilitate more efficient experimentation in which transformation efficiency is critical, such as yeast two-hybrid screening. PMID:27760994

Spent yeast as natural source of functional food additives

PubMed

Rakowska, Rita; Sadowska, Anna; Dybkowska, Ewa; Świderski, Franciszek

Spent yeasts are by-products arising from beer and wine production which over many years have been chiefly used as feed additives for livestock. They contain many valuable and bioactive substances which has thereby generated much interest in their exploitation. Up till now, the main products obtained from beer-brewing yeasts are β-glucans and yeast extracts. Other like foodstuffs include dried brewer’s yeast, where this is dried and the bitterness removed to be fit for human consumption as well as mannan-oligosaccharides hitherto used in the feed industry. β-glucans constitute the building blocks of yeast cell walls and can thus be used in human nutrition as dietary supplements or serving as food additives in functional foods. β-glucans products obtained via post-fermentation of beer also exhibit a high and multi-faceted biological activity where they improve the blood’s lipid profile, enhance immunological status and have both prebiotic and anti-oxidant properties. Yeast extracts are currently being used more and more to enhance flavour in foodstuffs, particularly for meat and its products. Depending on how autolysis is carried out, it is possible to design extracts of various meat flavours characteristic of specific meats. Many different flavour profiles can be created which may be additionally increased in combination with vegetable extracts. Within the food market, yeast extracts can appear in various guises such as liquids, pastes or powders. They all contain significant amounts of glutamic acid, 5’-GMP and 5’-IMP nucleotides together with various amino acids and peptides that act synergistically for enhancing the flavour of foodstuff products. Recent studies have demonstrated additional benefits of yeast extracts as valuable sources of amino acids and peptides which can be used in functional foods and dietary supplements. These products possess GRAS status (Generally Recognised As Safe) which thereby also adds further as to why they should be used

[Thermoresistance in Saccharomyces cerevisiae yeasts].

PubMed

Kaliuzhin, V A

2011-01-01

Under natural conditions, yeast Saccharomyces cerevisiae reproduce, as a rule, on the surface of solid or liquid medium. Thus, life cycle of yeast populations is substantially influenced by diurnal changes in ambient temperature. The pattern in the response of unrestricted yeast S. cerevisiae culture to changes in the temperature of cultivation is revealed experimentally. Yeast population, in the absence of environmental constraints on the functioning of cell chemosmotic bioenergetic system, demonstrates the ability of thermoresistance when the temperature of cultivation switches from the range of 12-36 degrees C to 37.5-40 degrees C. During the transient period that is associated with the temperature switching and lasts from 1 to 4 turnover cycles, yeast reproduction rate remains 1.5-2 times higher than under stationary conditions. This is due to evolutionary acquired adaptive activity of cell chemosmotic system. After the adaptive resources exhausting, yeast thermoresistance fully recovers at the temperature range of 12-36 degrees C within one generation time under conditions of both restricted and unrestricted nourishment. Adaptive significance of such thermoresistance seems obvious enough--it allows maintaining high reproduction rate in yeast when ambient temperature is reaching a brief maximum shortly after noon.

Influence of growth conditions on adhesion of yeast Candida spp. and Pichia spp. to stainless steel surfaces.

PubMed

Tomičić, Ružica; Raspor, Peter

2017-08-01

An understanding of adhesion behavior of Candida and Pichia yeast under different environmental conditions is key to the development of effective preventive measures against biofilm-associated infection. Hence in this study we investigated the impact of growth medium and temperature on Candida and Pichia adherence using stainless steel (AISI 304) discs with different degrees of surface roughness (Ra = 25.20-961.9 nm), material typical for the food processing industry as well as medical devices. The adhesion of the yeast strains to stainless steel surfaces grown in Malt Extract broth (MEB) or YPD broth at three temperatures (7 °C, 37 °C, 43 °C for Candida strains and 7 °C, 27 °C, 32 °C for Pichia strains) was assessed by crystal violet staining. The results showed that the nutrient content of medium significantly influenced the quantity of adhered cells by the tested yeasts. Adhesion of C. albicans and C. glabrata on stainless steel surfaces were significantly higher in MEB, whereas for C. parapsilosis and C. krusei it was YPD broth. In the case with P. pijperi and P. membranifaciens, YPD broth was more effective in promoting adhesion than MEB. On the other hand, our data indicated that temperature is a very important factor which considerably affects the adhesion of these yeast. There was also significant difference in cell adhesion on all types of stainless steel surfaces for all tested yeast. Copyright © 2017 Elsevier Ltd. All rights reserved.

Real-Time Quantitative PCR (QPCR) and Reverse Transcription-QPCR for Detection and Enumeration of Total Yeasts in Wine▿

PubMed Central

Hierro, Núria; Esteve-Zarzoso, Braulio; González, Ángel; Mas, Albert; Guillamón, Jose M.

2006-01-01

Real-time PCR, or quantitative PCR (QPCR), has been developed to rapidly detect and quantify the total number of yeasts in wine without culturing. Universal yeast primers were designed from the variable D1/D2 domains of the 26S rRNA gene. These primers showed good specificity with all the wine yeasts tested, and they did not amplify the most representative wine species of acetic acid bacteria and lactic acid bacteria. Numerous standard curves were constructed with different strains and species grown in yeast extract-peptone-dextrose medium or incubated in wine. The small standard errors with these replicas proved that the assay is reproducible and highly robust. This technique was validated with artificially contaminated and natural wine samples. We also performed a reverse transcription-QPCR (RT-QPCR) assay from rRNA for total viable yeast quantification. This technique had a low detection limit and was more accurate than QPCR because the dead cells were not quantified. As far as we know, this is the first time that RT-QPCR has been performed to quantify viable yeasts from rRNA. RT-QPCR is a rapid and accurate technique for enumerating yeasts during industrial wine fermentation and controlling the risk of wine spoilage. PMID:17088381

Use of sugarcane molasses "B" as an alternative for ethanol production with wild-type yeast Saccharomyces cerevisiae ITV-01 at high sugar concentrations.

PubMed

Fernández-López, C L; Torrestiana-Sánchez, B; Salgado-Cervantes, M A; García, P G Mendoza; Aguilar-Uscanga, M G

2012-05-01

Molasses "B" is a rich co-product of the sugarcane process. It is obtained from the second step of crystallization and is richer in fermentable sugars (50-65%) than the final molasses, with a lower non-sugar solid content (18-33%); this co-product also contains good vitamin and mineral levels. The use of molasses "B" for ethanol production could be a good option for the sugarcane industry when cane sugar prices diminish in the market. In a complex medium like molasses, osmotolerance is a desirable characteristic for ethanol producing strains. The aim of this work was to evaluate the use of molasses "B" for ethanol production using Saccharomyces cerevisiae ITV-01 (a wild-type yeast isolated from sugarcane molasses) using different initial sugar concentrations (70-291 g L(-1)), two inoculum sizes and the addition of nutrients such as yeast extract, urea, and ammonium sulphate to the culture medium. The results obtained showed that the strain was able to grow at 291 g L(-1) total sugars in molasses "B" medium; the addition of nutrients to the culture medium did not produce a statistically significant difference. This yeast exhibits high osmotolerance in this medium, producing high ethanol yields (0.41 g g(-1)). The best conditions for ethanol production were 220 g L(-1) initial total sugars in molasses "B" medium, pH 5.5, using an inoculum size of 6 × 10(6) cell mL(-1); ethanol production was 85 g L(-1), productivity 3.8 g L(-1 )h(-1) with 90% preserved cell viability.

Simple method for the extraction and reversed-phase high-performance liquid chromatographic analysis of carotenoid pigments from red yeasts (Basidiomycota, Fungi).

PubMed

Weber, Roland W S; Anke, Heidrun; Davoli, Paolo

2007-03-23

A simple method for the extraction of carotenoid pigments from frozen wet cells of red yeasts (Basidiomycota) and their analysis by reversed-phase HPLC using a C(18) column and a water/acetone solvent system is described. Typical red yeast carotenoids belonging to an oxidative series from the monocyclic gamma-carotene to 2-hydroxytorularhodin and from the bicyclic beta-carotene to astaxanthin were separated. Pigment identity was confirmed by LC-atmospheric pressure chemical ionisation (APCI) mass spectrometry using similar chromatographic conditions.

Phytate destruction by yeast fermentation in whole wheat meals. Study of high-extraction rate meals.

PubMed

Reinhold, J G

1975-01-01

Destruction of phytate by yeast fermentation is compared in sponges prepared from Iranian whole wheat meals of different extraction rates. Phytate was destroyed rapidly in whole meals of 75 to 85 and 85 to 90 per cent extraction, but destruction was retarded in those of 95 to 100 per cent extraction. Production of acid-soluble phosphorus kept pace with phytate destruction in the two whole meals of lower extraction rates but was delayed with less-than-expected yield in those of 95 to 100 per cent rate. Unleavened whole meal bread contains little acid-soluble phosphorus. Leavened breads made from whole meals of slightly lower extraction rate average five times as much. Since phytate phosphorus appears to remain unavailable in the small intestine in many circumstances, dependece on unleavened whole meal bread may result in critically low intakes of available phosphorus when other sources are lacking in the diet. It is concluded that replacement of the whole meals of 95 to 100 per cent extraction rate, presently the main staple of the diet of rural Iran, by those of somewhat lower rate is an important preliminary to the introduction of leaven and fermentation into village bread-making methods.

Urea enhances cell lysis of Schizosaccharomyces pombe ura4 mutants.

PubMed

Nishino, Kohei; Kushima, Misaki; Kaino, Tomohiro; Matsuo, Yasuhiro; Kawamukai, Makoto

2017-07-01

Cell lysis is induced in Schizosaccharomyces pombe ∆ura4 cells grown in YPD medium, which contains yeast extract, polypeptone, and glucose. To identify the medium components that induce cell lysis, we first tested various kinds of yeast extracts from different suppliers. Cell lysis of ∆ura4 cells on YE medium was observed when yeast extracts from OXOID, BD, Oriental, and Difco were used, but not when using yeast extract from Kyokuto. To determine which compounds induced cell lysis, we subjected yeast extract and polypeptone to GC-MS analysis. Ten kinds of compounds were detected in OXOID and BD yeast extracts, but not in Kyokuto yeast extract. Among them was urea, which was also present in polypeptone, and it clearly induced cell lysis. Deletion of the ure2 gene, which is responsible for utilizing urea, abolished the lytic effect of urea. The effect of urea was suppressed by deletion of pub1, and a similar phenotype was observed in the presence of polypeptone. Thus, urea is an inducer of cell lysis in S. pombe ∆ura4 cells.

Yeast ecology of Kombucha fermentation.

PubMed

Teoh, Ai Leng; Heard, Gillian; Cox, Julian

2004-09-01

Kombucha is a traditional fermentation of sweetened tea, involving a symbiosis of yeast species and acetic acid bacteria. Despite reports of different yeast species being associated with the fermentation, little is known of the quantitative ecology of yeasts in Kombucha. Using oxytetracycline-supplemented malt extract agar, yeasts were isolated from four commercially available Kombucha products and identified using conventional biochemical and physiological tests. During the fermentation of each of the four products, yeasts were enumerated from both the cellulosic pellicle and liquor of the Kombucha. The number and diversity of species varied between products, but included Brettanomyces bruxellensis, Candida stellata, Schizosaccharomyces pombe, Torulaspora delbrueckii and Zygosaccharomyces bailii. While these yeast species are known to occur in Kombucha, the enumeration of each species present throughout fermentation of each of the four Kombucha cultures demonstrated for the first time the dynamic nature of the yeast ecology. Kombucha fermentation is, in general, initiated by osmotolerant species, succeeded and ultimately dominated by acid-tolerant species.

Fish meal extract bile esculin agar (FMBE) a selective medium for Bacteroides fragilis group.

PubMed

Beena, V K; Rao, S; Kotian, M; Shivananda, P G

1997-07-01

Fish meal extract bile esculin agar (FMBE) is prepared using Fish meal extract concentrate as the basal substance, for the selective isolation and presumptive identification of B.fragilis group. The efficiency of the medium was evaluated by growing stock cultures of B.fragilis groups as well as inoculating clinical specimens and comparing the results with Bacteroides bile esculin agar (BBE). All the 87 stock cultures of B.fragilis grew on FMBE and BBE. No other anaerobes tested grew on the medium. However 7 out of 65 neomycin resistant aerobes grew on the FMBE. From the 100 clinical samples, 62 strains of B. Fragilis group were recovered on FMBE and BBE, and 53 strains on supplemented BHIBA. The cost effectiveness, selectivity and the ability to detect esculin hydrolysis will enable FMBE as a suitable medium as comparable to that of BBE, if not superior.

Improvement of aromatic thiol release through the selection of yeasts with increased β-lyase activity.

PubMed

Belda, Ignacio; Ruiz, Javier; Navascués, Eva; Marquina, Domingo; Santos, Antonio

2016-05-16

The development of a selective medium for the rapid differentiation of yeast species with increased aromatic thiol release activity has been achieved. The selective medium was based on the addition of S-methyl-l-cysteine (SMC) as β-lyase substrate. In this study, a panel of 245 strains of Saccharomyces cerevisiae strains was tested for their ability to grow on YCB-SMC medium. Yeast strains with an increased β-lyase activity grew rapidly because of their ability to release ammonium from SMC in comparison to others, and allowed for the easy isolation and differentiation of yeasts with promising properties in oenology, or another field, for aromatic thiol release. The selective medium was also helpful for the discrimination between those S. cerevisiae strains, which present a common 38-bp deletion in the IRC7 sequence (present in around 88% of the wild strains tested and are likely to be less functional for 4-mercapto-4-methylpentan-2-one (4MMP) production), and those S. cerevisiae strains homozygous for the full-length IRC7 allele. The medium was also helpful for the selection of non-Saccharomyces yeasts with increased β-lyase activity. Based on the same medium, a highly sensitive, reproducible and non-expensive GC-MS method for the evaluation of the potential volatile thiol release by different yeast isolates was developed. Copyright © 2016 Elsevier B.V. All rights reserved.

Interactions between yeast lees and wine polyphenols during simulation of wine aging. II. Analysis of desorbed polyphenol compounds from yeast lees.

PubMed

Mazauric, Jean-Paul; Salmon, Jean-Michel

2006-05-31

In the first part of this work, the analysis of the polyphenolic compounds remaining in the wine after different contact times with yeast lees during simulation of red wine aging was undertaken. To achieve a more precise view of the wine polyphenols adsorbed on lees during red wine aging and to establish a clear balance between adsorbed and remnant polyphenol compounds, the specific analysis of the chemical composition of the adsorbed polyphenolic compounds (condensed tannins and anthocyanins) after their partial desorbtion from yeast lees by denaturation treatments was realized in the second part of the study. The total recovery of polyphenol compounds from yeast lees was not complete, since a rather important part of the initial wine colored polyphenols, especially those with a dominant blue color component, remained strongly adsorbed on yeast lees, as monitored by color tristimulus and reflectance spectra measurements. All anthocyanins were recovered at a rather high percentage (about 62%), and it was demonstrated that they were not adsorbed in relation with their sole polarity. Very few monomeric phenolic compounds were extracted from yeast lees. With the use of drastic denaturing treatments, the total recovery of condensed tannins reached 83%. Such tannins extracted from yeast lees exhibited very high polymeric size and a rather high percentage of galloylated residues by comparison with initial wine tannins, indicating that nonpolar tannins were preferentially desorbed from yeast lees by the extraction treatments.

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

PubMed Central

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

2018-01-01

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

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

PubMed

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

2018-01-01

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

Zinc-containing yeast extract promotes nonrapid eye movement sleep in mice.

PubMed

Cherasse, Yoan; Saito, Hitomi; Nagata, Nanae; Aritake, Kosuke; Lazarus, Michael; Urade, Yoshihiro

2015-10-01

Zinc is an essential trace element for humans and animals, being located, among other places, in the synaptic vesicles of cortical glutamatergic neurons and hippocampal mossy fibers in the brain. Extracellular zinc has the potential to interact with and modulate many different synaptic targets, including glutamate and GABA receptors. Because of the central role of these neurotransmitters in brain activity, we examined in this study the sleep-promoting activity of zinc by monitoring locomotor activity and electroencephalogram after its administration to mice. Zinc-containing yeast extract (40 and 80 mg/kg) dose dependently increased the total amount of nonrapid eye movement sleep and decreased the locomotor activity. However, this preparation did not change the amount of rapid eye movement sleep or show any adverse effects such as rebound of insomnia during a period of 24 h following the induction of sleep; whereas the extracts containing other divalent cations (manganese, iron, and copper) did not decrease the locomotor activity. This is the first evidence that zinc can induce sleep. Our data open the way to new types of food supplements designed to improve sleep. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kinetic behavior of Candida guilliermondii yeast during xylitol production from Brewer's spent grain hemicellulosic hydrolysate.

PubMed

Mussatto, Solange I; Dragone, Giuliano; Roberto, Inês C

2005-01-01

Brewer's spent grain, the main byproduct of breweries, was hydrolyzed with dilute sulfuric acid to produce a hemicellulosic hydrolysate (containing xylose as the main sugar). The obtained hydrolysate was used as cultivation medium by Candidaguilliermondii yeast in the raw form (containing 20 g/L xylose) and after concentration (85 g/L xylose), and the kinetic behavior of the yeast during xylitol production was evaluated in both media. Assays in semisynthetic media were also performed to compare the yeast performance in media without toxic compounds. According to the results, the kinetic behavior of the yeast cultivated in raw hydrolysate was as effective as in semisynthetic medium containing 20 g/L xylose. However, in concentrated hydrolysate medium, the xylitol production efficiency was 30.6% and 42.6% lower than in raw hydrolysate and semisynthetic medium containing 85 g/L xylose, respectively. In other words, the xylose-to-xylitol bioconversion from hydrolysate medium was strongly affected when the initial xylose concentration was increased; however, similar behavior did not occur from semisynthetic media. The lowest efficiency of xylitol production from concentrated hydrolysate can be attributed to the high concentration of toxic compounds present in this medium, resulting from the hydrolysate concentration process.

Improvement of growth, fermentative efficiency and ethanol tolerance of Kloeckera africana during the fermentation of Agave tequilana juice by addition of yeast extract.

PubMed

Díaz-Montaño, Dulce M; Favela-Torres, Ernesto; Córdova, Jesus

2010-01-30

The aim of this work was to improve the productivity and yield of tequila fermentation and to propose the use of a recently isolated non-Saccharomyces yeast in order to obtain a greater diversity of flavour and aroma of the beverage. For that, the effects of the addition of different nitrogen (N) sources to Agave tequilana juice on the growth, fermentative capacity and ethanol tolerance of Kloeckera africana and Saccharomyces cerevisiae were studied and compared. Kloeckera africana K1 and S. cerevisiae S1 were cultured in A. tequilana juice supplemented with ammonium sulfate, diammonium phosphate or yeast extract. Kloeckera africana did not assimilate inorganic N sources, while S. cerevisiae utilised any N source. Yeast extract stimulated the growth, fermentative capacity and alcohol tolerance of K. africana, giving kinetic parameter values similar to those calculated for S. cerevisiae. This study revealed the importance of supplementing A. tequilana juice with a convenient N source to achieve fast and complete conversion of sugars in ethanol, particularly in the case of K. africana. This yeast exhibited similar growth and fermentative capacity to S. cerevisiae. The utilisation of K. africana in the tequila industry is promising because of its variety of synthesised aromatic compounds, which would enrich the attributes of this beverage. (c) 2009 Society of Chemical Industry.

Long-Term n-Caproic Acid Production from Yeast-Fermentation Beer in an Anaerobic Bioreactor with Continuous Product Extraction.

PubMed

Ge, Shijian; Usack, Joseph G; Spirito, Catherine M; Angenent, Largus T

2015-07-07

Multifunctional reactor microbiomes can elongate short-chain carboxylic acids (SCCAs) to medium-chain carboxylic acids (MCCAs), such as n-caproic acid. However, it is unclear whether this microbiome biotechnology platform is stable enough during long operating periods to consistently produce MCCAs. During a period of 550 days, we improved the operating conditions of an anaerobic bioreactor for the conversion of complex yeast-fermentation beer from the corn kernel-to-ethanol industry into primarily n-caproic acid. We incorporated and improved in-line, membrane liquid-liquid extraction to prevent inhibition due to undissociated MCCAs at a pH of 5.5 and circumvented the addition of methanogenic inhibitors. The microbiome accomplished several functions, including hydrolysis and acidogenesis of complex organic compounds and sugars into SCCAs, subsequent chain elongation with undistilled ethanol in beer, and hydrogenotrophic methanogenesis. The methane yield was 2.40 ± 0.52% based on COD and was limited by the availability of carbon dioxide. We achieved an average n-caproate production rate of 3.38 ± 0.42 g L(-1) d(-1) (7.52 ± 0.94 g COD L(-1) d(-1)) with an n-caproate yield of 70.3 ± 8.81% and an n-caproate/ethanol ratio of 1.19 ± 0.15 based on COD for a period of ∼55 days. The maximum production rate was achieved by increasing the organic loading rates in tandem with elevating the capacity of the extraction system and a change in the complex feedstock batch.

Effects of yeast extract and vitamin D on turkey mortality and cellulitis incidence in a transport stress model.

USDA-ARS?s Scientific Manuscript database

We evaluated yeast extract (YE) and vitamin D (VD) in turkeys treated with dexamethasone (Dex) at intervals designed to simulate transport stress during a 3 stage growout. YE but not VD decreased early mortality (P = 0.001) and mortality at wk 7 (P= 0.02) and wk 12 (P = 0.002) but not wk 16. Celluli...

Optimum production and characterization of an acid protease from marine yeast Metschnikowia reukaufii W6b

NASA Astrophysics Data System (ADS)

Li, Jing; Peng, Ying; Wang, Xianghong; Chi, Zhenming

2010-12-01

The marine yeast strain W6b isolated from sediment of the South China Sea was found to produce a cell-bound acid protease. The crude acid protease produced by this marine yeast showed the highest activity at pH 3.5 and 40 °C. The optimal pH and temperature for the crude acid protease were in agreement with those for acid protease produced by the terrestrial yeasts. The optimal medium of the acid protease production was seawater containing 1.0% glucose, 1.5% casein, and 0.5% yeast extract, and the optimal cultivation conditions of the acid protease production were pH 4.0, a temperature of 25 °C and a shaking speed of 140 rmin-1. Under the optimal conditions, 72.5 UmL-1 of acid protease activity could be obtained in cell suspension within 48 h of fermentation at shake flask level. The acid protease production was induced by high-molecular-weight nitrogen sources and repressed by low-molecular-weight nitrogen sources. Skimmed-milk-clotting test showed that the crude acid protease from the cell suspension of the yeast W6b had high skimmed milk coagulability. The acid protease produced by M. reukaufii W6b may have highly potential applications in cheese, food and fermentation industries.

Cocoa butter-like lipid production ability of non-oleaginous and oleaginous yeasts under nitrogen-limited culture conditions.

PubMed

Wei, Yongjun; Siewers, Verena; Nielsen, Jens

2017-05-01

Cocoa butter (CB) extracted from cocoa beans is the main raw material for chocolate production. However, growing chocolate demands and limited CB production has resulted in a shortage of CB supply. CB is mainly composed of three different kinds of triacylglycerols (TAGs), POP (C16:0-C18:1-C16:0), POS (C16:0-C18:1-C18:0), and SOS (C18:0-C18:1-C18:0). The storage lipids of yeasts, mainly TAGs, also contain relative high-level of C16 and C18 fatty acids and might be used as CB-like lipids (CBL). In this study, we cultivated six different yeasts, including one non-oleaginous yeast strain, Saccharomyces cerevisiae CEN.PK113-7D, and five oleaginous yeast strains, Trichosporon oleaginosus DSM11815, Rhodotorula graminis DSM 27356, Lipomyces starkeyi DSM 70296, Rhodosporidium toruloides DSM 70398, and Yarrowia lipolytica CBS 6124, in nitrogen-limited medium and compared their CBL production ability. Under the same growth conditions, we found that TAGs were the main lipids in all six yeasts and that T. oleaginosus can produce more TAGs than the other five yeasts. Less than 3% of the total TAGs were identified as potential SOS in the six yeasts. However, T. oleaginosus produced 27.8% potential POP and POS at levels of 378 mg TAGs/g dry cell weight, hinting that this yeast may have potential as a CBL production host after further metabolic engineering in future.

Impact of a packing medium with alga Bifurcaria bifurcata extract on canned Atlantic mackerel (Scomber scombrus) quality.

PubMed

Barbosa, Roberta G; Trigo, Marcos; Fett, Roseane; Aubourg, Santiago P

2018-01-03

The present research focused on the quality of canned fish. Its primary objective was the quality enhancement of canned Atlantic mackerel (Scomber scombrus) by including an aqueous Bifurcaria bifurcata extract in the packing medium. Various alga extract concentrations were tested and compared with a control without alga extract. After 3 months of canned storage, the cans were opened and quality changes in fish white muscle were analyzed. An inhibitory effect on lipid oxidation development (tertiary compound formation) and color parameter (L* and b*) values was observed as a result of the alga presence in the packing medium. On the contrary, the presence of the alga extract did not produce any effect on volatile compound (total and trimethylamine) formation and lipid hydrolysis (free fatty acid formation) development. A preservative effect derived from the use of an aqueous B. bifurcata extract as packing medium is concluded, and this result is primarily linked to the presence of hydrophilic preservative molecules. The packing system proposed in this work constitutes a novel and promising strategy to enhance the quality of commercial canned fish products. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Germanium precipitation from collecting-mains liquor with tannin extract in an alkaline medium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medvedev, K.P.; Mikhailov, N.F.; Petrapol'skaya, V.M.

1976-01-01

It is proposed to precipitate germanium in a slightly alkaline medium, with a neutral solution of tannin extract in aqueous alkali. The effects of various factors on germanium recovery from collecting-mains liquors have been studied.

Effects of different yeast cell wall supplements added to maize- or wheat-based diets for broiler chickens.

PubMed

Morales-López, R; Auclair, E; Van Immerseel, F; Ducatelle, R; García, F; Brufau, J

2010-06-01

1. Three experiments were carried out to study the effects of two experimental yeast cell wall (YCW) supplements, one from the yeast extract industry and the other from the brewery industry, added to maize or wheat based-diets, on performance and intestinal parameters of broiler chickens (Ross 308). 2. In the first and second experiments, a completely randomised block design with 4 experimental treatments was used: T-1) Negative control, no additives T-2) Positive control, avilamycin group (10 mg/kg feed), T-3) Yeast extract-YCW (500 mg/kg), and T-4) Brewery-YCW (500 mg/kg feed). There were 6 replicates of 20 (experiment 1) and 22 (experiment 2) chicks per treatment. 3. In experiment 1 (wheat based diets), yeast extract-YCW increased BW and daily feed intake (42 d). The effects were comparable to those of avilamycin. In experiment 2 (maize based diet), avilamycin, yeast extract-YCW and brewery-YCW treatments improved the feed conversion ratio with respect to the negative control group (0 to 14 d). 4. At 24 d, in both experiments, the ileal nutrient digestibility and ileal bacterial counts were not affected by any experimental treatment. In maize diets, lower intestinal viscosity was obtained with avilamycin, yeast extract-YCW and brewery-YCW than with the negative control. In wheat diets, yeast extract-YCW and brewery-YCW reduced intestinal viscosity. 5. A third experiment was conducted to study the effect of yeast extract-YCW on animal performance, intestinal mucosa morphology and intestinal viscosity. A 2 x 2 factorial arrangement of treatments was used; one factor was the dietary yeast extract-YCW supplementation (0 or 500 mg/kg feed) and the other the cereal in the diet (maize or wheat). 6. At 43 d, the heaviest BW was in chickens fed on yeast extract-YCW compared to those given the negative control. At 22 d, yeast extract-YCW increased villus height, mucus thickness and number of goblet cells with respect to negative control. 7. Results of these experiments

Extracellular enzymatic activities and physiological profiles of yeasts colonizing fruit trees.

PubMed

Molnárová, Jana; Vadkertiová, Renáta; Stratilová, Eva

2014-07-01

Yeasts form a significant and diverse part of the phyllosphere microbiota. Some yeasts that inhabit plants have been found to exhibit extracellular enzymatic activities. The aim of the present study was to investigate the ability of yeasts isolated from leaves, fruits, and blossoms of fruit trees cultivated in Southwest Slovakia to produce extracellular enzymes, and to discover whether the yeasts originating from these plant organs differ from each other in their physiological properties. In total, 92 strains belonging to 29 different species were tested for: extracellular protease, β-glucosidase, lipase, and polygalacturonase activities; fermentation abilities; the assimilation of xylose, saccharose and alcohols (methanol, ethanol, glycerol); and for growth in a medium with 33% glucose. The black yeast Aureobasidium pullulans showed the largest spectrum of activities of all the species tested. Almost 70% of the strains tested demonstrated some enzymatic activity, and more than 90% utilized one of the carbon compounds tested. Intraspecies variations were found for the species of the genera Cryptococcus and Pseudozyma. Interspecies differences of strains exhibiting some enzymatic activities and utilizing alcohols were also noted. The largest proportion of the yeasts exhibited β-glucosidase activity and assimilated alcohols independently of their origin. The highest number of strains positive for all activities tested was found among the yeasts associated with leaves. Yeasts isolated from blossoms assimilated saccharose and D-xylose the most frequently of all the yeasts tested. The majority of the fruit-inhabiting yeasts grew in the medium with higher osmotic pressure. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yeast vitality during cider fermentation: assessment by energy metabolism.

PubMed

Dinsdale, M G; Lloyd, D; McIntyre, P; Jarvis, B

1999-03-15

In an apple juice-based medium, an ethanol-tolerant Australian wine-yeast used for cider manufacture produced more than 10% ethanol over a 5 week period. Growth of the inoculum (10(6) organisms ml(-1)) occurred to a population of 3.1 x 10(7) ml(-1) during the first few days; at the end of the fermentation only 5 x 10(5) yeasts ml(-1) could be recovered as colony-forming units on plates. Respiratory and fermentative activities were measured by mass spectrometric measurements (O2 consumption and CO2 and ethanol production) of washed yeast suspensions taken from the cider fermentation at intervals. Both endogenous and glucose-supported energy-yielding metabolism declined, especially during the first 20 days. Levels of adenine nucleotides also showed decreases after day 1, as did adenylate energy charge, although in a prolonged (16.5 week) fermentation the lowest value calculated was 0.55. AMP was released into the medium. 31P-NMR spectra showed that by comparison with aerobically grown yeast, that from the later stages of the cider fermentation showed little polyphosphate. However, as previously concluded from studies of 'acidification power' and fluorescent oxonol dye exclusion (Dinsdale et al., 1995), repitching of yeast indicated little loss of viability despite considerable loss of vitality.

Interactions of grape tannins and wine polyphenols with a yeast protein extract, mannoproteins and β-glucan.

PubMed

Mekoue Nguela, J; Poncet-Legrand, C; Sieczkowski, N; Vernhet, A

2016-11-01

At present, there is a great interest in enology for yeast derived products to replace aging on lees in winemaking or as an alternative for wine fining. These are yeast protein extracts (YPE), cell walls and mannoproteins. Our aim was to further understand the mechanisms that drive interactions between these components and red wine polyphenols. To this end, interactions between grape skin tannins or wine polyphenols or tannins and a YPE, a mannoprotein fraction and a β-glucan were monitored by binding experiments, ITC and DLS. Depending on the tannin structure, a different affinity between the polyphenols and the YPE was observed, as well as differences in the stability of the aggregates. This was attributed to the mean degree of polymerization of tannins in the polyphenol fractions and to chemical changes that occur during winemaking. Much lower affinities were found between polyphenols and polysaccharides, with different behaviors between mannoproteins and β-glucans. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of medium components on the production of a biosurfactant from Candida tropicalis applied to the removal of hydrophobic contaminants in soil.

PubMed

Batista, Ranielly M; Rufino, Raquel D; Luna, Juliana M; de Souza, José Edson G; Sarubbo, Leonie A

2010-05-01

The influence of medium constituents on the production of biosurfactants by Candida tropicalis cultivated in waste frying oil was investigated according to a fractional factorial 2(5-1) design. The combined effect of the C/N(inorganic), C/Fe, C/Mg, and C/P ratios and yeast extract on surface tension reduction, biosurfactant yield, emulsification activity, and biomass were studied. The highest biosurfactant yield was reached when low C/Mg and low C/P ratio variables were combined, while the cell growth was favored by increasing the nitrogen concentration. The highest surface tension net decrease, on the other hand, was observed at low yeast extract concentration, low C/Fe, and high C/P ratios. Emulsification indices against lubrication and automobile waste oil of approximately 65 to 95% were observed. The crude biosurfactant produced in the medium--formulated with 2% waste frying oil, 0.067% NH4Cl, 0.025% MgSO4.7H2O, 0.067% KH2PO4, and 0.0026% FeCl3.6H2O--removed approximately 78 to 97% of the petroleum and motor oil adsorbed in sand samples.

Fuel ethanol production from Jerusalem artichoke stalks using different yeasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Margaritis, A.; Bajpai, P.; Bajpai, P.K.

1983-01-01

The inulin-type sugars present in the stalks of Jerusalem artichoke (Helianthus tuberosus) were extracted with hot water and were used as a substrate to produce fuel EtOH. Seven different yeasts were used to obtain batch kinetic data. The medium consisted of stalk extract from Jerusalem artichoke containing 7.3% total sugars, supplemented with 0.01% oleic acid, 0.01% corn steep liquor, and 0.05% Tween 80. All batch fermentations were carried out in a 1-L bioreactor at 35 degrees and pH 4.6, and the following parameters were measured as a function of time: total sugars, EtOH and biomass concentration, maximum specific growth rate,more » and biomass and EtOH yields. The best EtOH producer was Kluyveromyces marxianus UCD (FST) 55-82 which gave an EtOH-to-sugar yield 97% of the theoretical maximum value, with almost 100% sugar utilization.« less

Identification of oleaginous yeast strains able to accumulate high intracellular lipids when cultivated in alkaline pretreated corn stover

PubMed Central

Sitepu, Irnayuli R.; Jin, Mingjie; Fernandez, J. Enrique; da Costa Sousa, Leonardo; Balan, Venkatesh; Boundy-Mills, Kyria L.

2015-01-01

Microbial oil is a potential alternative to food/plant-derived biodiesel fuel. Our previous screening studies identified a wide range of oleaginous yeast species, using a defined laboratory medium known to stimulate lipid accumulation. In this study, the ability of these yeasts to grow and accumulate lipids was further investigated in synthetic hydrolysate (SynH) and authentic ammonia fiber expansion (AFEX™)-pretreated corn stover hydrolysate (ACSH). Most yeast strains tested were able to accumulate lipids in SynH, but only a few were able to grow and accumulate lipids in ACSH medium. Cryptococcus humicola UCDFST 10-1004 was able to accumulate as high as 15.5 g/L lipids, out of a total of 36 g/L cellular biomass when grown in ACSH, with a cellular lipid content of 40% of cell dry weight. This lipid production is among the highest reported values for oleaginous yeasts grown in authentic hydrolysate. Pre-culturing in SynH media with xylose as sole carbon source enabled yeasts to assimilate both glucose and xylose more efficiently in the subsequent hydrolysate medium. This study demonstrates that ACSH is a suitable medium for certain oleaginous yeasts to convert lignocellullosic sugars to triacylglycerols for production of biodiesel and other valuable oleochemicals. PMID:25052467

Response surface optimization of the critical medium components for pullulan production by Aureobasidium pullulans FB-1.

PubMed

Singh, Ram Sarup; Singh, Harpreet; Saini, Gaganpreet Kaur

2009-01-01

Culture conditions for pullulan production by Aureobasidium pullulans were optimized using response surface methodology at shake flask level without pH control. In the present investigation, a five-level with five-factor central composite rotatable design of experiments was employed to optimize the levels of five factors significantly affecting the pullulan production, biomass production, and sugar utilization in submerged cultivation. The selected factors included concentration of sucrose, ammonium sulphate, yeast extract, dipotassium hydrogen phosphate, and sodium chloride. Using this methodology, the optimal values for concentration of sucrose, ammonium sulphate, yeast extract, dipotassium hydrogen phosphate, and sodium chloride were 5.31%, 0.11%, 0.07%, 0.05%, and 0.15% (w/v), respectively. This optimized medium has projected a theoretically production of pullulan of 4.44%, biomass yield of 1.03%, and sugar utilization of 97.12%. The multiple correlation coefficient 'R' was 0.9976, 0.9761 and 0.9919 for pullulan production, biomass production, and sugar utilization, respectively. The value of R being very close to one justifies an excellent correlation between the predicted and the experimental data.

Optimization growth of Spirulina platensis in bean sprouts extract medium with urea fertilizer for phycocyanin production as antioxidant

NASA Astrophysics Data System (ADS)

Dianursanti, Taurina, Zarahmaida; Indraputri, Claudia Maya

2018-02-01

Spirulina platensis has the potential to be developed because of essential chemical compounds in the form of phycocyanin that can be used as an antioxidant. The growth of microalgae and phycocyanin depends on the availability of nutrition contained in culture medium. The cultivation will be carried out at 1 L reactor with continuous aeration, light intensity is 3000-4000 lux, and temperature is 27-30°C. Phycocyanin is obtained by liquid-liquid extraction method using phosphate buffer pH 7. Phycocyanin test performed by using UV-Vis spectrophotometry. The result show that the highest dry biomass is obtained on bean sprouts extract medium 8% (v/v) with the addition of urea fertilizer 120 ppm. The highest content of phycocyanin is obtained on bean sprouts extract medium 8% (v/v) with the addition of urea fertilizer 100 ppm with phycocyanin concentration of 257.12 mg/L.

Asymmetric bioreduction of acetophenones by Baker's yeast and its cell-free extract encapsulated in sol-gel silica materials

NASA Astrophysics Data System (ADS)

Kato, Katsuya; Nakamura, Hitomi; Nakanishi, Kazuma

2014-02-01

Baker's yeast (BY) encapsulated in silica materials was synthesized using a yeast cell suspension and its cell-free extract during a sol-gel reaction of tetramethoxysilane with nitric acid as a catalyst. The synthesized samples were fully characterized using various methods, such as scanning electron microscopy, nitrogen adsorption-desorption, Fourier transform infrared spectroscopy, thermogravimetry, and differential thermal analysis. The BY cells were easily encapsulated inside silica-gel networks, and the ratio of the cells in the silica gel was approximately 75 wt%, which indicated that a large volume of BY was trapped with a small amount of silica. The enzyme activity (asymmetric reduction of prochiral ketones) of BY and its cell-free extract encapsulated in silica gel was investigated in detail. The activities and enantioselectivities of free and encapsulated BY were similar to those of acetophenone and its fluorine derivatives, which indicated that the conformation structure of BY enzymes inside silica-gel networks did not change. In addition, the encapsulated BY exhibited considerably better solvent (methanol) stability and recyclability compared to free BY solution. We expect that the development of BY encapsulated in sol-gel silica materials will significantly impact the industrial-scale advancement of high-efficiency and low-cost biocatalysts for the synthesis of valuable chiral alcohols.

Recovery of Fuel-Precursor Lipids from Oleaginous Yeast

DOE PAGES

Kruger, Jacob S.; Cleveland, Nicholas S.; Yeap, Rou Yi; ...

2018-01-24

Bio-derived lipids offer a potentially promising intermediate to displace petroleum-derived diesel. One of the key challenges for the production of lipids via microbial cell mass is that these products are stored intracellularly and must be extracted and recovered efficiently and economically. Thus, improved methods of cell lysis and lipid extraction are needed. In this study, we examine lipid extraction from wet oleaginous yeast in combination with seven different cell lysis approaches encompassing both physical and chemical techniques (high-pressure homogenization, microwave and conventional thermal treatments, bead beating, acid, base, and enzymatic treatments) to facilitate lipid extraction from a model oleaginous yeastmore » strain, Lipomyces starkeyi. Of the seven techniques investigated, acid treatment led to the highest lipid recovery yields. Further exploration of acid treatment and integration with an economic model revealed that treatment at 170 degrees C for 60 min at 1 wt% H 2SO 4 and 8 wt% yeast solids represents a viable option for both lipid recovery yield and process economics, enabling experimental lipid recovery yields of 88.5-93.0% to be achieved at a corresponding estimated minimum fuel selling price (MFSP) of $5.13-$5.61/gallon of gasoline equivalent (GGE). The same acid treatment conditions applied to two other strains of oleaginous yeast (Cutaneotrichosporon curvatus and Rhodotorula toruloides) resulted in similar lipid recovery yields. In pretreatment experiments scaled up to 300 mL, slightly lower temperatures or shorter pretreatment times, along with higher yeast solids loading, resulted in higher lipid yields than the conditions identified from the small-scale runs. Two replicate runs carried out at 170 degrees C for 30 min using 1 wt% H2SO4 and 19 wt% yeast solids achieved an average lipid recovery of 96.1% at a corresponding estimated MFSP of $4.89/GGE. In all cases, the lipids are primarily triglycerides and free fatty acids

Recovery of Fuel-Precursor Lipids from Oleaginous Yeast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruger, Jacob S.; Cleveland, Nicholas S.; Yeap, Rou Yi

Bio-derived lipids offer a potentially promising intermediate to displace petroleum-derived diesel. One of the key challenges for the production of lipids via microbial cell mass is that these products are stored intracellularly and must be extracted and recovered efficiently and economically. Thus, improved methods of cell lysis and lipid extraction are needed. In this study, we examine lipid extraction from wet oleaginous yeast in combination with seven different cell lysis approaches encompassing both physical and chemical techniques (high-pressure homogenization, microwave and conventional thermal treatments, bead beating, acid, base, and enzymatic treatments) to facilitate lipid extraction from a model oleaginous yeastmore » strain, Lipomyces starkeyi. Of the seven techniques investigated, acid treatment led to the highest lipid recovery yields. Further exploration of acid treatment and integration with an economic model revealed that treatment at 170 degrees C for 60 min at 1 wt% H 2SO 4 and 8 wt% yeast solids represents a viable option for both lipid recovery yield and process economics, enabling experimental lipid recovery yields of 88.5-93.0% to be achieved at a corresponding estimated minimum fuel selling price (MFSP) of $5.13-$5.61/gallon of gasoline equivalent (GGE). The same acid treatment conditions applied to two other strains of oleaginous yeast (Cutaneotrichosporon curvatus and Rhodotorula toruloides) resulted in similar lipid recovery yields. In pretreatment experiments scaled up to 300 mL, slightly lower temperatures or shorter pretreatment times, along with higher yeast solids loading, resulted in higher lipid yields than the conditions identified from the small-scale runs. Two replicate runs carried out at 170 degrees C for 30 min using 1 wt% H2SO4 and 19 wt% yeast solids achieved an average lipid recovery of 96.1% at a corresponding estimated MFSP of $4.89/GGE. In all cases, the lipids are primarily triglycerides and free fatty acids

Medium optimization for ε-poly-L-lysine production by Streptomyces diastatochromogenes using response surface methodology.

PubMed

Guo, F; Zheng, H; Cheng, Y; Song, S; Zheng, Z; Jia, S

2018-02-01

Poly-ε-L-lysine is a natural homo-polyamide of L-lysine with excellent antimicrobial properties, which can be used as a novel preservative and has a wide range of applications. In this paper, the fermentation medium for ε-PL production by Streptomyces diastatochromogenes 6#-7 was optimized by Response Surface Methodology. The results of Plackett-Burman design showed that glucose, yeast extract and (NH 4 ) 2 SO 4 were the major influencing factors in ε-PL production of S. diastatochromogenes 6#-7. The optimal concentrations of glucose, yeast extract and (NH 4 ) 2 SO 4 were determined to be 60, 7·5 and 7·5 g l -1 according to Box-Behnken experiment and regression analysis, respectively. Under the optimized conditions, the ε-PL yield in shake-flask fermentation was 0·948 ± 0·030 g l -1 , which was in good agreement with the predicted value of 0·970 g l -1 . The yield was improved by 43·1% from that with the initial medium. In 5 l jar-fermenter the ε-PL yield reached 25·5 g l -1 , which was increased by 56·4% from the original medium. In addition, the fermentation time was reduced from 174 to 120 h. Medium optimization is a very practical and valuable tool for fermentation industry to improve product yield and minimize by-products as well as reduce overall manufacturing costs. The response surface methodology is not new, but it is still a very effective method in medium optimization research. This study used ε-polylysine fermentation as an example to demonstrate how the product yield can be significantly increased by medium optimization through surface response methodology. Similar approach can be used in other microbial fermentations such as in pharmaceutical, food, agricultural and energy industries. As an example, ε-polylysine is one of a few newly approved natural food-grade antimicrobials for food and beverages preservations. Yield improvement is economically beneficial to not only ε-polylysine manufacturers but also to their users and

The effect of growth medium on B. anthracis Sterne spore carbohydrate content.

PubMed

Colburn, Heather A; Wunschel, David S; Antolick, Kathryn C; Melville, Angela M; Valentine, Nancy B

2011-06-01

The expressed characteristics of biothreat agents may be impacted by variations in the culture environment, including growth medium formulation. The carbohydrate composition of B. anthracis spores has been well studied, particularly for the exosporium, which is the outermost spore structure. The carbohydrate composition of the exosporium has been demonstrated to be distinct from the vegetative form containing unique monosaccharides. We have investigated the carbohydrate composition of B. anthracis Sterne spores produced using four different medium types formulated with different sources of medium components. The amount of rhamnose, 3-O-methyl rhamnose and galactosamine was found to vary significantly between spores cultured using different medium formulations. The relative abundance of these monosaccharides compared to other monosaccharides such as mannosamine was also found to vary with medium type. Specific medium components were also found to impact the carbohydrate profile. Xylose has not been previously described in B. anthracis spores but was detected at low levels in two media. This may represent residual material from the brewery yeast extract used to formulate these two media. These results illustrate the utility of this method to capture the impact of growth medium on carbohydrate variation in spores. Detecting carbohydrate profiles in B. anthracis evidentiary material may provide useful forensic information on the growth medium used for sporulation. Copyright © 2011 Elsevier B.V. All rights reserved.

Transcriptional activation of a geranylgeranyl diphosphate synthase gene, GGPPS2, isolated from Scoparia dulcis by treatment with methyl jasmonate and yeast extract.

PubMed

Yamamura, Y; Mizuguchi, Y; Taura, F; Kurosaki, F

2014-10-01

A cDNA clone, designated SdGGPPS2, was isolated from young seedlings of Scoparia dulcis. The putative amino acid sequence of the translate of the gene showed high homology with geranylgeranyl diphosphate synthase (GGPPS) from various plant sources, and the N-terminal residues exhibited the characteristics of chloroplast targeting sequence. An appreciable increase in the transcriptional level of SdGGPPS2 was observed by exposure of the leaf tissues of S. dulcis to methyl jasmonate, yeast extract or Ca(2+) ionophore A23187. In contrast, SdGGPPS1, a homologous GGPPS gene of the plant, showed no or only negligible change in the expression level upon treatment with these stimuli. The truncated protein heterologously expressed in Escherichia coli in which the putative targeting domain was deleted catalyzed the condensation of farnesyl diphosphate and isopentenyl diphosphate to liberate geranylgeranyl diphosphate. These results suggested that SdGGPPS2 plays physiological roles in methyl jasmonate and yeast extract-induced metabolism in the chloroplast of S. dulcis cells.

Production of astaxanthin rich feed supplement for animals from Phaffia rhodozyma yeast at low cost

NASA Astrophysics Data System (ADS)

Irtiza, Ayesha; Shatunova, Svetlana; Glukhareva, Tatiana; Kovaleva, Elena

2017-09-01

Dietary nutrients such as amino acids, vitamins, minerals and antioxidants can play a significant role in determining meat quality and also the growth rate of poultry or animal. Phaffia rhodozyma was grown on waste from brewery industry to produce astaxanthin rich feed supplements at a very low cost. Phaffia rhodozyma is yeast specie that has ability to produce carotenoids and approximately 80% of its total carotenoid content is astaxanthin, which is highly valuable carotenoid for food, feed and aquaculture industry. This study was carried out to test yeast extract of spent yeast from brewing industry waste (residual yeast) as potential nitrogen source for growth of Phaffia rhodozyma. Cultivation was carried out in liquid media prepared by yeast extracts and other components (glucose and peptone). Carotenoids from the biomass were released into biomass by suspending cells in DMSO for destruction of cells followed by extraction with petroleum ether. The extracted carotenoids were studied by spectrophotometry to identify and quantify astaxanthin and other carotenoids produced.

Thermodynamic analysis of fermentation and anaerobic growth of baker's yeast for ethanol production.

PubMed

Teh, Kwee-Yan; Lutz, Andrew E

2010-05-17

Thermodynamic concepts have been used in the past to predict microbial growth yield. This may be the key consideration in many industrial biotechnology applications. It is not the case, however, in the context of ethanol fuel production. In this paper, we examine the thermodynamics of fermentation and concomitant growth of baker's yeast in continuous culture experiments under anaerobic, glucose-limited conditions, with emphasis on the yield and efficiency of bio-ethanol production. We find that anaerobic metabolism of yeast is very efficient; the process retains more than 90% of the maximum work that could be extracted from the growth medium supplied to the chemostat reactor. Yeast cells and other metabolic by-products are also formed, which reduces the glucose-to-ethanol conversion efficiency to less than 75%. Varying the specific ATP consumption rate, which is the fundamental parameter in this paper for modeling the energy demands of cell growth, shows the usual trade-off between ethanol production and biomass yield. The minimum ATP consumption rate required for synthesizing cell materials leads to biomass yield and Gibbs energy dissipation limits that are much more severe than those imposed by mass balance and thermodynamic equilibrium constraints. 2010 Elsevier B.V. All rights reserved.

Pyrene degradation by yeasts and filamentous fungi.

PubMed

Romero, M Cristina; Salvioli, Mónica L; Cazau, M Cecilia; Arambarri, A M

2002-01-01

The saprotrophic soil fungi Fusarium solani (Mart.) Sacc., Cylindrocarpon didymum (Hartig) Wollenw, Penicillium variabile Sopp. and the yeasts Rhodotorula glutinis (Fresenius) Harrison and Rhodotorula minuta (Saito) Harrison were cultured in mineral medium with pyrene. The remaining pyrene concentrations were periodically determined during 20 incubation days, using HPLC. To assess the metabolism of pyrene degradation we added 0.1 microCi of [4,5,9,10] 14C-pyrene to each fungi culture and measured the radioactivity in the volatile organic substances, extractable, aqueous phase, biomass and 14CO2 fractions. The assays demonstrated that F. solani and R. glutinis metabolized pyrene as a sole source of carbon. Differences in their activities at the beginning of the cultures disappeared by the end of the experiment, when 32 and 37% of the original pyrene concentration was detected, for the soil fungi and yeasts, respectively. Among the filamentous fungi, F. solani was highly active and oxidized pyrene; moreover, small but significant degradation rates were observed in C. didymum and P. variahile cultures. An increase in the 14CO2 evolution was observed at the 17th day with cosubstrate. R. glutinis and R. minuta cultures showed similar ability to biotransform pyrene, and that 35% of the initial concentration was consumed at the end of the assay. The same results were obtained in the experiments with or without glucose as cosubstrate.

Optimization of culture conditions and medium composition for the marine algicidal bacterium Alteromonas sp. DH46 by uniform design

NASA Astrophysics Data System (ADS)

Lin, Jing; Zheng, Wei; Tian, Yun; Wang, Guizhong; Zheng, Tianling

2013-09-01

Harmful algal blooms (HABs) have led to extensive ecological and environmental issues and huge economic losses. Various HAB control techniques have been developed, and biological methods have been paid more attention. Algicidal bacteria is a general designation for bacteria which inhibit algal growth in a direct or indirect manner, and kill or damage the algal cells. A metabolite which is strongly toxic to the dinoflagellate Alexandrium tamarense was produced by strain DH46 of the alga-lysing bacterium Alteromonas sp. The culture conditions were optimized using a single-factor test method. Factors including carbon source, nitrogen source, temperature, initial pH value, rotational speed and salinity were studied. The results showed that the cultivation of the bacteria at 28°C and 180 r min-1 with initial pH 7 and 30 salt contcentration favored both the cell growth and the lysing effect of strain DH46. The optimal medium composition for strain DH46 was determined by means of uniform design experimentation, and the most important components influencing the cell density were tryptone, yeast extract, soluble starch, NaNO3 and MgSO4. When the following culture medium was used (tryptone 14.0g, yeast extract 1.63g, soluble starch 5.0 g, NaNO3 1.6 g, MgSO4 2.3 g in 1L), the largest bacterial dry weight (7.36 g L-1) was obtained, which was an enhancement of 107% compared to the initial medium; and the algal lysis rate was as high as 98.4% which increased nearly 10% after optimization.

Yeast Biomass Production in Brewery's Spent Grains Hemicellulosic Hydrolyzate

NASA Astrophysics Data System (ADS)

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

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

Glycerol metabolism and transport in yeast and fungi: established knowledge and ambiguities.

PubMed

Klein, Mathias; Swinnen, Steve; Thevelein, Johan M; Nevoigt, Elke

2017-03-01

There is huge variability among yeasts with regard to their efficiency in utilizing glycerol as the sole source of carbon and energy. Certain species show growth rates with glycerol comparable to those reached with glucose as carbon source; others are virtually unable to utilize glycerol, especially in synthetic medium. Most of our current knowledge regarding glycerol uptake and catabolic pathways has been gained from studying laboratory strains of the model yeast Saccharomyces cerevisiae. The growth of these strains on glycerol is dependent on the presence of medium supplements such as amino acids and nucleobases. In contrast, there is only fragmentary knowledge about S. cerevisiae isolates able to grow in synthetic glycerol medium without such supplements as well as about growth of non-Saccharomyces yeast species on glycerol. Thus, more research is required to understand why certain strains and species show superior growth performance on glycerol compared with common S. cerevisiae laboratory strains. This mini-review summarizes what is known so far about the gene products and pathways involved in glycerol metabolism and transport in yeast and fungi as well as the regulation of these processes. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

Antidiabetic activity of medium-polar extract from the leaves of Stevia rebaudiana Bert. (Bertoni) on alloxan-induced diabetic rats

PubMed Central

Misra, Himanshu; Soni, Manish; Silawat, Narendra; Mehta, Darshana; Mehta, B. K.; Jain, D. C.

2011-01-01

Objective: To investigate the medicative effects of medium-polar (benzene:acetone, 1:1, v/v) extract of leaves from Stevia rebaudiana (family Asteraceae) on alloxan-induced diabetic rats. Materials and Methods: Diabetes was induced in adult albino Wistar rats by intraperitoneal (i.p.) injection of alloxan (180 mg/kg). Medium-polar extract was administered orally at daily dose of 200 and 400 mg/kg body wt. basis for 10 days. The control group received normal saline (0.9%) for the same duration. Glibenclamide was used as positive control reference drug against Stevia extract. Results: Medium-polar leaf extract of S. rebaudiana (200 and 400 mg/kg) produced a delayed but significant (P < 0.01) decrease in the blood glucose level, without producing condition of hypoglycemia after treatment, together with lesser loss in the body weight as compared with standard positive control drug glibenclamide. Conclusions: Treatment of diabetes with sulfonylurea drugs (glibenclamide) causes hypoglycemia followed by greater reduction in body weight, which are the most worrisome effects of these drugs. Stevia extract was found to antagonize the necrotic action of alloxan and thus had a re-vitalizing effect on β-cells of pancreas. PMID:21687353

A new β-glucosidase producing yeast for lower-cost cellulosic ethanol production from xylose-extracted corncob residues by simultaneous saccharification and fermentation.

PubMed

Liu, Z Lewis; Weber, Scott A; Cotta, Michael A; Li, Shi-Zhong

2012-01-01

This study reports a new yeast strain of Clavispora NRRL Y-50464 that is able to utilize cellobiose as sole source of carbon and produce sufficient native β-glucosidase enzyme activity for cellulosic ethanol production using SSF. In addition, this yeast is tolerant to the major inhibitors derived from lignocellulosic biomass pre-treatment such as 2-furaldehyde (furfural) and 5-(hydroxymethyl)-2-furaldehyde (HMF), and converted furfural into furan methanol in less than 12h and HMF into furan-2,5-dimethanol within 24h in the presence of 15 mM each of furfural and HMF. Using xylose-extracted corncob residue as cellulosic feedstock, an ethanol production of 23 g/l was obtained using 25% solids loading at 37 °C by SSF without addition of exogenous β-glucosidase. Development of this yeast aids renewable biofuels development efforts for economic consolidated SSF bio-processing. Published by Elsevier Ltd.

Biosynthesis of higher alcohol flavour compounds by the yeast Saccharomyces cerevisiae: impact of oxygen availability and responses to glucose pulse in minimal growth medium with leucine as sole nitrogen source.

PubMed

Espinosa Vidal, Esteban; de Morais, Marcos Antonio; François, Jean Marie; de Billerbeck, Gustavo M

2015-01-01

Higher alcohol formation by yeast is of great interest in the field of fermented beverages. Among them, medium-chain alcohols impact greatly the final flavour profile of alcoholic beverages, even at low concentrations. It is widely accepted that amino acid metabolism in yeasts directly influences higher alcohol formation, especially the catabolism of aromatic and branched-chain amino acids. However, it is not clear how the availability of oxygen and glucose metabolism influence the final higher alcohol levels in fermented beverages. Here, using an industrial Brazilian cachaça strain of Saccharomyces cerevisiae, we investigated the effect of oxygen limitation and glucose pulse on the accumulation of higher alcohol compounds in batch cultures, with glucose (20 g/l) and leucine (9.8 g/l) as the carbon and nitrogen sources, respectively. Fermentative metabolites and CO2 /O2 balance were analysed in order to correlate the results with physiological data. Our results show that the accumulation of isoamyl alcohol by yeast is independent of oxygen availability in the medium, depending mainly on leucine, α-keto-acids and/or NADH pools. High-availability leucine experiments showed a novel and unexpected accumulation of isobutanol, active amyl alcohol and 2-phenylethanol, which could be attributed to de novo biosynthesis of valine, isoleucine and phenylalanine and subsequent outflow of these pathways. In carbon-exhausted conditions, our results also describe, for the first time, the metabolization of isoamyl alcohol, isobutanol, active amyl alcohol but not of 2-phenylethanol, by yeast strains in stationary phase, suggesting a role for these higher alcohols as carbon source for cell maintenance and/or redox homeostasis during this physiological phase. Copyright © 2014 John Wiley & Sons, Ltd.

[Process development for continuous ethanol fermentation by the flocculating yeast under stillage backset conditions].

PubMed

Zi, Lihan; Liu, Chenguang; Bai, Fengwu

2014-02-01

Propionic acid, a major inhibitor to yeast cells, was accumulated during continuous ethanol fermentation from corn meal hydrolysate by the flocculating yeast under stillage backset conditions. Based on its inhibition mechanism in yeast cells, strategies were developed for alleviating this effect. Firstly, high temperature processes such as medium sterilization generated more propionic acid, which should be avoided. Propionic acid was reduced significantly during ethanol fermentation without medium sterilization, and concentrations of biomass and ethanol increased by 59.3% and 7.4%, respectively. Secondly, the running time of stillage backset should be controlled so that propionic acid accumulated would be lower than its half inhibition concentration IC50 (40 mmol/L). Finally, because low pH augmented propionic acid inhibition in yeast cells, a higher pH of 5.5 was validated to be suitable for ethanol fermentation under the stillage backset condition.

Acanthopanax senticosus extracts have a protective effect on Drosophila gut immunity.

PubMed

Li, Wenjia; Luo, Qiuxiang; Jin, Li Hua

2013-03-07

Aanthopanax senticosus (A. senticosus) Harms is a classical adaptogenic agent used in China. It has been applied as an analeptic aid to improve weakened physical status. However, little is known about the effects of A. senticosus on inflammatory disease processes. Flies fed with standard cornmeal-yeast medium were used as controls, and the treatment groups contained 10% of A. senticosus aqueous extracts (root or fruit) in standard medium. Survival rate was performed by feeding a vial containing five layers of filter paper hydrated with 5% sucrose solution contaminated with pathogenic or toxic compounds. Imaging of the guts was viewed under the microscope. Death cells were detected by 7-AAD staining. The A. senticosus extract improved the survival rate, attenuated the death of intestinal epithelial cells, promoted the expression of antimicrobial peptide genes, and decreased the formation of melanotic masses. Moreover, our results indicated that the protective effect of fruit is much higher than that of root extracts. A. senticosus extracts have a protective effect on Drosophila gut immunity and stress response, and may contribute to the prevention of inflammatory diseases induced by pathogenic and toxic compounds. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Nonlinear Dielectric Properties of Yeast Cells Cultured in Different Environmental Conditions

NASA Astrophysics Data System (ADS)

Kawanishi, Gomon; Fukuda, Naoki; Muraji, Masafumi

The harmonics of the electric current through yeast suspensions, the nonlinear dielectric properties of yeast cells, have particular patterns according to the biological activity of the cells and the measurement of these patterns is a technique for determining the activity of living cells. The concentration of glucose and oxygen in yeast culture medium influences the manifestation of fermentation or respiration of yeast cells. Measurements were made with yeast cells (Saccharomyces cerevisiae) cultured aerobically and anaerobically in sufficient glucose concentration, aerobic fermentation and anaerobic fermentation, and aerobically in limited glucose concentration, respiration. The results showed that the harmonics were barely apparent for yeast cells in aerobic fermentation and respiratory; however, cells in the anaerobic fermentation displayed substantial third and fifth harmonics. We can say that environmental condition affects the yeast cells' nonlinear properties, from another viewpoint, the measurements of the nonlinear properties are available to determine the activity of yeast cells adjusted to the conditions of their cultivation.

Optimization of culture medium for anaerobic production of rhamnolipid by recombinant Pseudomonas stutzeri Rhl for microbial enhanced oil recovery.

PubMed

Zhao, F; Mandlaa, M; Hao, J; Liang, X; Shi, R; Han, S; Zhang, Y

2014-08-01

Response surface methodology was employed to enhance the anaerobic production of rhamnolipid by recombinant Pseudomonas stutzeri Rhl. Glycerol is a promising carbon source used to anaerobically produce rhamnolipid. In a Plackett-Burman design, glycerol, KH2 PO4 and yeast extract were significant factors. The proposed optimized medium contained the following: 46·55 g l(-1) glycerol; 3 g l(-1) NaNO3 ; 5·25 g l(-1) K2 HPO4 ·3H2 O; 5·71 g l(-1) KH2 PO4 ; 0·40 g l(-1) MgSO4 ·7H2 O; 0·13 g l(-1) CaCl2 ; 1·0 g l(-1) KCl; 1·0 g l(-1) NaCl; and 2·69 g l(-1) yeast extract. Using this optimized medium, we obtained an anaerobic yield of rhamnolipid of 3·12 ± 0·11 g l(-1) with a 0·85-fold increase. Core flooding test results also revealed that Ps. stutzeri Rhl grown in an optimized medium enhanced the oil recovery efficiency by 15·7%, which was 6·6% higher than in the initial medium. Results suggested that the optimized medium is a promising nutrient source that could effectively mobilize oil by enhancing the in situ production of rhamnolipid. The ex situ application of rhamnolipid for microbial enhanced oil recovery (MEOR) is costly and complex in terms of rhamnolipid production, purification and transportation. Compared with ex situ applications, the in situ production of rhamnolipid in anaerobic oil reservoir is more advantageous for MEOR. This study is the first to report the anaerobic production optimization of rhamnolipid. Results showed that the optimized medium enhanced not only the anaerobic production of rhamnolipid but also crude oil recovery. © 2014 The Society for Applied Microbiology.

Characterization of Alicyclobacillus disufldooxidans HIB4 Isolated from an Acid Mine Drainage Treatment Plant

NASA Astrophysics Data System (ADS)

Suto, Koichi; Joe, Seong Jin; Inoue, Chihiro; Chida, Tadashi

2006-05-01

A heterotrophic bacterium, designated as HIB4, having an ability to oxidize ferrous iron was isolated from the sample of an enrichment culture with 9K medium, by using the modified WAYE (washed agarose/yeast extract) medium with ferrous sulphate. This isolate was identified as Alicyclobacillus disulfidooxidans from 16S rDNA sequence analysis. The isolate grew and oxidized ferrous iron in an inorganic medium containing 0.02 % (w/v) of yeast extract and Ferrous iron oxidation occurred at the almost end of its logarithmic phase. Yeast extract was an essential substrate for the isolate because the isolate could not grow or oxidize ferrous iron without yeast extract. However, higher concentration of yeast extract inhibited the growth of the isolate. On the other hand, it was confirmed that the isolate was able to grow without ferrous ion so that it did not get any energy by ferrous ion oxidation. Its optimum concentration of yeast extract was 0.02% (w/v) at the concentration of ferrous ion 0.08mol/liter. Its optimum pH was 1.5 and the optimum temperature was 30 °C These physiological characteristics were completely different from A. disulfidooxidans SD-11 which is the type strain.

Development and use of a selective medium for isolation of Leuconostoc spp. from vegetables and dairy products.

PubMed Central

Benkerroum, N; Misbah, M; Sandine, W E; Elaraki, A T

1993-01-01

A selective medium (LUSM medium) for the isolation of Leuconostoc spp. was developed. This medium contained 1.0% glucose, 1.0% Bacto Peptone (Difco), 0.5% yeast extract (BBL), 0.5% meat extract (Difco), 0.25% gelatin (Difco), 0.5% calcium lactate, 0.05% sorbic acid, 75 ppm of sodium azide (Sigma), 0.25% sodium acetate, 0.1% (vol/vol) Tween 80, 15% tomato juice, 30 micrograms of vancomycin (Sigma) per ml, 0.20 microgram of tetracycline (Serva) per ml, 0.5 mg of cysteine hydrochloride per ml, and 1.5% agar (Difco). LUSM medium was used successfully for isolation and enumeration of Leuconostoc spp. in dairy products and vegetables. Of 116 colony isolates obtained from fresh raw milk, curdled milk, or various vegetables, 115 were identified as members of the genus Leuconostoc. A total of 89 of these isolates were identified to species; 13.5% of the isolates were Leuconostoc cremoris, 7.9% were Leuconostoc mesenteroides subsp. mesenteroides, 11.2% were Leuconostoc mesenteroides subsp. dextranicum, 16.9% were Leuconostoc mesenteroides subsp. paramesenteroides, 10.1% were leuconostoc lactis, and 40.4% were Leuconostoc oenos. When we compared the counts obtained for two Leuconostoc strains, Leuconostoc dextranicum 181 and L. cremoris JLL8, on MRS agar and LUSM medium, we found no significant difference between the values obtained on the two media. PMID:8434926

Optimisation of medium composition for probiotic biomass production using response surface methodology.

PubMed

Anvari, Masumeh; Khayati, Gholam; Rostami, Shora

2014-02-01

This study was aimed to optimise lactose, inulin and yeast extract concentration and also culture pH for maximising the growth of a probiotic bacterium, Bifidobacterium animalis subsp. lactis in apple juice and to assess the effects of these factors by using response surface methodology. A second-order central composite design was applied to evaluate the effects of these independent variables on growth of the microorganism. A polynomial regression model with cubic and quadratic terms was used for analysis of the experimental data. It was found that the effects involving inulin, yeast extract and pH on growth of the bacterium were significant, and the strongest effect was given by the yeast extract concentration. Estimated optimum conditions of the factors on the bacterial growth are as follows: lactose concentration=9·5 g/l; inulin concentration=38·5 mg/l; yeast extract concentration=9·6 g/l and initial pH=6·2.

New medium for rapid screening and enumeration of Clostridium perfringens in foods.

PubMed Central

Erickson, J E; Deibel, R H

1978-01-01

A rapid and sensitive procedure for estimating low numbers of Clostridium perfringens has been investigated and compared to methods used currently in the food industry. The new liquid medium, RPM (rapid perfringens medium), was compared with sulfite-polymyxin-sulfadiazine agar and tryptose-sulfite-cycloserine agar in recovery studies with naturally contaminated and with inoculated foods. The medium consists of a mixture of litmus milk and fluid thioglycolate medium fortified with glucose, peptone, gelatin, yeast extract, sodium chloride, and ferrous sulfate. Selectivity is based on an antibiotic system (polymyxin B sulfate and neomycin sulfate) incorporated into the medium, coupled with an incubation temprature of 46 to 48 degrees C for 24 h. Tubes were scored as positive if a stormy fermentation was observed. All tubes demonstrating stormy fermentation were confirmed as containing C. perfringens. Of a total of 774 naturally contaminated food samples, 546 samples (71%) were found to contain C. perfringens with RPM, whereas only 168 (22%) of the samples were positive using sulfite-polymyxin-sulfadiazine agar. C. perfringens was isolated from 71% of 85 other samples using RPM as compared to 14% with tryptose-sulfite-cycloserine agar. Enumeration studies on 14 individual samples using the most probable number technique also demonstrated greater sensitivity with RPM. PMID:213019

Astaxanthinogenesis in the yeast Phaffia rhodozyma - optimization of low-cost culture media and yeast cell-wall lysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fontana, J.D.; Baron, M.; Guimaraes, M.F.

Astaxanthin is a diketo-dihydroxy-carotenoid produced by Phaffia rhodozyma, a basidiomicetous yeast. A low-cost fermentation medium consisting of raw sugarcane juice and urea was developed to exploit the active sucrolytic/urelolytic enzyme apparatus inherent to the yeast. As compared to the beneficial effect of 0.1 g% urea, a ready nitrogen source, mild phosphoric pre inversion of juice sucrose to glucose and fructose, promptly fermentable carbon sources, resulted in smaller benefits. Corn steep liquor (CSL) was found to be a valuable supplement for both yeast biomass yield (9.2 g dry cells/L) and astaxanthin production (1.3 mg/g cells). Distillery effluent (vinace), despite only amore » slightly positive effect on yeast growth, allowed for the highest pigment productivity (1.9 mg/g cells). Trace amounts of Ni{sup 2} (1 mg/L, as a cofactor for urease) resulted in controversial effects, namely, biomass decrease and astaxanthin increase, with no effect on the release (and uptake) of ammonium ion from urea. 13 refs., 6 figs.« less

Laboratory evolution of copper tolerant yeast strains

PubMed Central

2012-01-01

Background Yeast strains endowed with robustness towards copper and/or enriched in intracellular Cu might find application in biotechnology processes, among others in the production of functional foods. Moreover, they can contribute to the study of human diseases related to impairments of copper metabolism. In this study, we investigated the molecular and physiological factors that confer copper tolerance to strains of baker's yeasts. Results We characterized the effects elicited in natural strains of Candida humilis and Saccharomyces cerevisiae by the exposure to copper in the culture broth. We observed that, whereas the growth of Saccharomyces cells was inhibited already at low Cu concentration, C. humilis was naturally robust and tolerated up to 1 g · L-1 CuSO4 in the medium. This resistant strain accumulated over 7 mg of Cu per gram of biomass and escaped severe oxidative stress thanks to high constitutive levels of superoxide dismutase and catalase. Both yeasts were then "evolved" to obtain hyper-resistant cells able to proliferate in high copper medium. While in S. cerevisiae the evolution of robustness towards Cu was paralleled by the increase of antioxidative enzymes, these same activities decreased in evolved hyper-resistant Candida cells. We also characterized in some detail changes in the profile of copper binding proteins, that appeared to be modified by evolution but, again, in a different way in the two yeasts. Conclusions Following evolution, both Candida and Saccharomyces cells were able to proliferate up to 2.5 g · L-1 CuSO4 and to accumulate high amounts of intracellular copper. The comparison of yeasts differing in their robustness, allowed highlighting physiological and molecular determinants of natural and acquired copper tolerance. We observed that different mechanisms contribute to confer metal tolerance: the control of copper uptake, changes in the levels of enzymes involved in oxidative stress response and changes in the copper

Yeast Communities of Chestnut Soils under Vineyards in Dagestan

NASA Astrophysics Data System (ADS)

Abdullabekova, D. A.; Magomedova, E. S.; Magomedov, G. G.; Aliverdieva, D. A.; Kachalkin, A. V.

2017-12-01

The study of yeast communities in chestnut soils (Kastanozems) under vineyards in the Republic of Dagestan made it possible to isolate 20 yeast species. Most of the yeasts under vineyards belonged to ascomycetes, among which species of the Saccharomycetaceae family (in particular, Saccharomyces cerevisiae) comprised a significant part. The obtained results indicate that the soils under vineyards keep the pool of microbial diversity and ensure preservation of many species typical for grapes. The method of enrichment culture on grape juice medium proved to be more efficient than other methods of analysis with respect to the number of isolated species and the rate of their detection. However, implementation of different techniques to study yeasts' diversity can give somewhat different results; a set of methods should be used for an integrated analysis.

Optimization of culture conditions and medium composition for the production of micrococcin GO5 by Micrococcus sp. GO5.

PubMed

Kim, Mi-Hee; Kong, Yoon-Jung; Baek, Hong; Hyun, Hyung-Hwan

2006-01-02

To enhance the production of micrococcin GO5, a bacteriocin produced by Micrococcus sp. GO5, cultivation conditions and medium composition were optimized. The optimal initial pH and temperature for bacteriocin production were 7.0-9.0 and 37 degrees C, respectively. Micrococcus sp. GO5 displayed the highest micrococcin GO5 activity when grown in modified MRS medium that contained lactose or sucrose, rather than glucose, as a carbon source. The maximum bacteriocin activity was obtained in modified MRS medium containing 0.5% tryptone and 1.0% yeast extract as nitrogen sources instead of the other nitrogen sources present in MRS medium. Bacteriocin production was greatly affected by the concentration of K(2)HPO(4); strain GO5 produced eight-fold more bacteriocin in medium containing 2.0-2.5% K(2)HPO(4) than in medium containing 0.2% K(2)HPO(4). The optimal concentration of MgSO(4).7H(2)O for bacteriocin production was 0.5%. The production of micrococcin GO5 was increased 32-fold in shake flask culture and 16-fold in a bioreactor using the optimized medium (TY medium), compared with culturing in MRS medium.

A Four-Hour Yeast Bioassay for the Direct Measure of Estrogenic Activity in Wastewater without Sample Extraction, Concentration, or Sterilization

PubMed Central

Balsiger, Heather A.; de la Torre, Roberto; Lee, Wen-Yee; Cox, Marc B.

2010-01-01

The assay described here represents an improved yeast bioassay that provides a rapid yet sensitive screening method for EDCs with very little hands-on time and without the need for sample preparation. Traditional receptor-mediated reporter assays in yeast were performed twelve to twenty four hours after ligand addition, used colorimetric substrates, and, in many cases, required high, non-physiological concentrations of ligand. With the advent of new chemiluminescent substrates a ligand-induced signal can be detected within thirty minutes using high picomolar to low nanomolar concentrations of estrogen. As a result of the sensitivity (EC50 for estradiol is ~ 0.7 nM) and the very short assay time (2-4 hours) environmental water samples can typically be assayed directly without sterilization, extraction, and concentration. Thus, these assays represent rapid and sensitive approaches for determining the presence of contaminants in environmental samples. As proof of principle, we directly assayed wastewater influent and effluent taken from a wastewater treatment plant in the El Paso, TX area for the presence of estrogenic activity. The data obtained in the four-hour yeast bioassay directly correlated with GC-mass spectrometry analysis of these same water samples. PMID:20074779

Nuclear Magnetic Resonance Spectroscopy-Based Identification of Yeast.

PubMed

Himmelreich, Uwe; Sorrell, Tania C; Daniel, Heide-Marie

2017-01-01

Rapid and robust high-throughput identification of environmental, industrial, or clinical yeast isolates is important whenever relatively large numbers of samples need to be processed in a cost-efficient way. Nuclear magnetic resonance (NMR) spectroscopy generates complex data based on metabolite profiles, chemical composition and possibly on medium consumption, which can not only be used for the assessment of metabolic pathways but also for accurate identification of yeast down to the subspecies level. Initial results on NMR based yeast identification where comparable with conventional and DNA-based identification. Potential advantages of NMR spectroscopy in mycological laboratories include not only accurate identification but also the potential of automated sample delivery, automated analysis using computer-based methods, rapid turnaround time, high throughput, and low running costs.We describe here the sample preparation, data acquisition and analysis for NMR-based yeast identification. In addition, a roadmap for the development of classification strategies is given that will result in the acquisition of a database and analysis algorithms for yeast identification in different environments.

Oxygen requirements of yeasts. [Saccharomyces cerevisiae; Candida tropicalis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Visser, W.; Scheffers, W.A.; Batenburg-Van Der Vegte, W.H.

1990-12-01

Type species of 75 yeast genera were examined for their ability to grow anaerobically in complex and mineral media. To define anaerobic conditions, we added a redox indicator, resazurin, to the media to determine low redox potentials. All strains tested were capable of fermenting glucose to ethanol in oxygen-limited shake-flask cultures, even those of species generally regarded as nonfermentative. However, only 23% of the yeast species tested grew under anaerobic conditions. A comparative study with a number of selected strains revealed that Saccharomyces cerevisiae stands out as a yeast capable of rapid growth at low redox potentials. Other yeasts, suchmore » as Torulaspora delbrueckii and Candida tropicalis, grew poorly ({mu}{sub max}, 0.03 and 0.05 h{sup {minus}1}, respectively) under anaerobic conditions in mineral medium supplemented with Tween 80 and ergosterol. The latter organisms grew rapidly under oxygen limitation and then displayed a high rate of alcoholic fermentation. It can be concluded that these yeasts have hitherto-unidentified oxygen requirements for growth.« less

Method for using a yeast alpha-amylase promoter

DOEpatents

Gao, Johnway; Skeen, Rodney S.; Hooker, Brian S.; Anderson, Daniel B.

2003-04-22

The present invention provides the promoter clone discovery of an alpha-amylase gene of a starch utilizing yeast strain Schwanniomyces castellii. The isolated alpha-amylase promoter is an inducible promoter, which can regulate strong gene expression in starch culture medium.

Molecular Characterization of the Elaeis guineensis Medium-Chain Fatty Acid Diacylglycerol Acyltransferase DGAT1-1 by Heterologous Expression in Yarrowia lipolytica.

PubMed

Aymé, Laure; Jolivet, Pascale; Nicaud, Jean-Marc; Chardot, Thierry

2015-01-01

Diacylglycerol acyltransferases (DGAT) are involved in the acylation of sn-1,2-diacylglycerol. Palm kernel oil, extracted from Elaeis guineensis (oil palm) seeds, has a high content of medium-chain fatty acids mainly lauric acid (C12:0). A putative E. guineensis diacylglycerol acyltransferase gene (EgDGAT1-1) is expressed at the onset of lauric acid accumulation in the seed endosperm suggesting that it is a determinant of medium-chain triacylglycerol storage. To test this hypothesis, we thoroughly characterized EgDGAT1-1 activity through functional complementation of a Yarrowia lipolytica mutant strain devoid of neutral lipids. EgDGAT1-1 expression is sufficient to restore triacylglycerol accumulation in neosynthesized lipid droplets. A comparative functional study with Arabidopsis thaliana DGAT1 highlighted contrasting substrate specificities when the recombinant yeast was cultured in lauric acid supplemented medium. The EgDGAT1-1 expressing strain preferentially accumulated medium-chain triacylglycerols whereas AtDGAT1 expression induced long-chain triacylglycerol storage in Y. lipolytica. EgDGAT1-1 localized to the endoplasmic reticulum where TAG biosynthesis takes place. Reestablishing neutral lipid accumulation in the Y. lipolytica mutant strain did not induce major reorganization of the yeast microsomal proteome. Overall, our findings demonstrate that EgDGAT1-1 is an endoplasmic reticulum DGAT with preference for medium-chain fatty acid substrates, in line with its physiological role in palm kernel. The characterized EgDGAT1-1 could be used to promote medium-chain triacylglycerol accumulation in microbial-produced oil for industrial chemicals and cosmetics.

Molecular Characterization of the Elaeis guineensis Medium-Chain Fatty Acid Diacylglycerol Acyltransferase DGAT1-1 by Heterologous Expression in Yarrowia lipolytica

PubMed Central

Aymé, Laure; Jolivet, Pascale; Nicaud, Jean-Marc; Chardot, Thierry

2015-01-01

Diacylglycerol acyltransferases (DGAT) are involved in the acylation of sn-1,2-diacylglycerol. Palm kernel oil, extracted from Elaeis guineensis (oil palm) seeds, has a high content of medium-chain fatty acids mainly lauric acid (C12:0). A putative E. guineensis diacylglycerol acyltransferase gene (EgDGAT1-1) is expressed at the onset of lauric acid accumulation in the seed endosperm suggesting that it is a determinant of medium-chain triacylglycerol storage. To test this hypothesis, we thoroughly characterized EgDGAT1-1 activity through functional complementation of a Yarrowia lipolytica mutant strain devoid of neutral lipids. EgDGAT1-1 expression is sufficient to restore triacylglycerol accumulation in neosynthesized lipid droplets. A comparative functional study with Arabidopsis thaliana DGAT1 highlighted contrasting substrate specificities when the recombinant yeast was cultured in lauric acid supplemented medium. The EgDGAT1-1 expressing strain preferentially accumulated medium-chain triacylglycerols whereas AtDGAT1 expression induced long-chain triacylglycerol storage in Y. lipolytica. EgDGAT1-1 localized to the endoplasmic reticulum where TAG biosynthesis takes place. Reestablishing neutral lipid accumulation in the Y. lipolytica mutant strain did not induce major reorganization of the yeast microsomal proteome. Overall, our findings demonstrate that EgDGAT1-1 is an endoplasmic reticulum DGAT with preference for medium-chain fatty acid substrates, in line with its physiological role in palm kernel. The characterized EgDGAT1-1 could be used to promote medium-chain triacylglycerol accumulation in microbial-produced oil for industrial chemicals and cosmetics. PMID:26581109

Biostimulation effects of low-energy laser radiation on yeast cell suspensions

NASA Astrophysics Data System (ADS)

Anghel, Sorin; Stanescu, Constantin S.; Giosanu, Dana; Neagu, Ionica; Savulescu, Geta; Iorga-Siman, Ion

2000-02-01

This paper presents work to determine the effects produced by low energy laser radiation on the metabolism and growth of a yeast cell suspension. As experimental material, we used young yeast culture in liquid medium, then distributed on a solid medium, to obtain isolated colonies. As laser source, we used a He-Ne laser, and the irradiation was made with different exposure times. Form each irradiated material, a sample of white grape sterile must was sowed, that has fermented at 18 divided by 20 degrees C for 10 divided by 15 days, after that some properties was tested. Some microscopic studies were also made. The results prove some influence of low energy laser irradiation, which can induce mutations, with new properties of the irradiated material. These mutations can be obtained in a positive sense, with new and important perspectives in wine industry. Also, we observed an inhibitory effect of the laser radiation on the yeast cell growth, due, probably to the too high values of the exposure.

Isolation of oligotrophic yeasts from supraglacial environments of different altitude on the Gulkana Glacier (Alaska).

PubMed

Uetake, Jun; Yoshimura, Yoshitaka; Nagatsuka, Naoko; Kanda, Hiroshi

2012-11-01

Psychrophilic yeasts have been isolated from supra- and subglacial ice at many sites worldwide. To understand the ecology of psychrophilic yeasts on glaciers, we focused on their adaptation to wide range of nutrient concentrations and their distribution with altitude on the Gulkana Glacier in Alaska. We found various culturable psychrophilic yeasts on the ice surfaces of the glacier, and 11 species were isolated with incubation at 4 °C in four different dilutions of agar medium. Some of our isolated species (Rhodotorula psychrophenolica, Rhodotorula aff. psychrophenolica, Rhodotorula glacialis, and Basidiomycota sp. 1) can grow on the low dissolved organic matter (DOC) concentrations medium (7.6 mg L(-1)) which is close to the typical level of supraglacial melt water, suggesting that these species can inhabit in any supraglacial meltwater. Otherwise, most of other species were isolated only from higher DOC concentration medium (183 mg L(-1) -18.3 g L(-1)), suggesting that these are inhabitant around the cryoconite, because DOC concentrations in melted surface-ice contained cryoconite is much higher than in melted water. Similarity of altitudinal distribution between culturable yeast and algal biomass suggests that the ecological role played by the cold-adapted yeasts is as organic matter decomposers and nutrient cyclers in glacier ecosystem. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

COCOA (Theobroma cacao) Polyphenol-Rich Extract Increases the Chronological Lifespan of Saccharomyces cerevisiae.

PubMed

Baiges, I; Arola, L

2016-01-01

BACKGROUND: Saccharomyces cerevisiae is a model organism with conserved aging pathways. Yeast chronological lifespan experiments mimic the processes involved in human non-dividing tissues, such as the nervous system or skeletal muscle, and can speed up the search for biomolecules with potential anti-aging effects before proceeding to animal studies. OBJECTIVE: To test the effectiveness of a cocoa polyphenol-rich extract (CPE) in expanding the S. cerevisiae chronological lifespan in two conditions: in the stationary phase reached after glucose depletion and under severe caloric restriction. MEASUREMENTS: Using a high-throughput method, wild-type S. cerevisiae and its mitochondrial manganese-dependent superoxide dismutase null mutant (sod2Δ) were cultured in synthetic complete dextrose medium. After 2 days, 0, 5 and 20 mg/ml of CPE were added, and viability was measured throughout the stationary phase. The effects of the major components of CPE were also evaluated. To determine yeast lifespan under severe caloric restriction conditions, cultures were washed with water 24 h after the addition of 0 and 20 mg/ml of CPE, and viability was followed over time. RESULTS : CPE increased the chronological lifespan of S. cerevisiae during the stationary phase in a dose-dependent manner. A similar increase was also observed in (sod2Δ). None of the major CPE components (theobromine, caffeine, maltodextrin, (-)-epicatechin, (+)-catechin and procyanidin B2) was able to increase the yeast lifespan. CPE further increased the yeast lifespan under severe caloric restriction. CONCLUSION: CPE increases the chronological lifespan of S. cerevisiae through a SOD2-independent mechanism. The extract also extends yeast lifespan under severe caloric restriction conditions. The high-throughput assay used makes it possible to simply and rapidly test the efficacy of a large number of compounds on yeast aging, requiring only small amounts, and is thus a convenient screening assay to accelerate

Synergistic effect of sodium and yeast in improving the efficiency of DSSC sensitized with extract from petals of Kigelia Africana

NASA Astrophysics Data System (ADS)

Shalini, S.; Balasundaraprabhu, R.; Satish Kumar, T.; Sivakumaran, K.; Kannan, M. D.

2018-05-01

TiO2 nanostructures with two different dopants, sodium and yeast have been successfully synthesized by hydrothermal method. Doping sodium is found to extend the absorbance of TiO2 into the visible region as well as it acts as mordant in fixing and improving the absorption of dye. Yeast, as a dopant, can help in absorption of more anthocyanins from the natural dye extract by TiO2 and also aids in retaining the colour of the dye and increases the stability of the dye at varying pH. Anthocyanins are the major class of pigment present in the newly addressed maroon, velvety and trumpet shaped flower "Kigelia Africana". X-ray diffraction analysis revealed the formation of rutile phase for all the samples. Field Emission Scanning Electron microscopy images revealed the formation of nanorods and nanoflowers with change in dopant as well as their concentration. The photoelectric conversion efficiency of DSSC with undoped TiO2 photoelectrode is 0.87% and DSSC with 6% Na doped TiO2 photoelectrode is 1.56%. The efficiency of DSSC with 6% Na+6% yeast doped TiO2 photoelectrode is found to increase from 2.09% (DSSC with 6% Na+4% yeast doped TiO2 photoelectrode) to 2.31% on varying the dopant concentration. Doping is also found to increase the dye absorption and superior charge transport efficiency which in turn helps to improve the performance of DSSC.

Optimization of a corn steep medium for production of ethanol from synthesis gas fermentation by Clostridium ragsdalei.

PubMed

Saxena, Jyotisna; Tanner, Ralph S

2012-04-01

Fermentation of biomass derived synthesis gas to ethanol is a sustainable approach that can provide more usable energy and environmental benefits than food-based biofuels. The effects of various medium components on ethanol production by Clostridium ragsdalei utilizing syngas components (CO:CO(2)) were investigated, and corn steep liquor (CSL) was used as an inexpensive nutrient source for ethanol production by C. ragsdalei. Elimination of Mg(2+), NH(4) (+) and PO(4) (3-) decreased ethanol production from 38 to 3.7, 23 and 5.93 mM, respectively. Eliminating Na(+), Ca(2+), and K(+) or increasing Ca(2+), Mg(2+), K(+), NH(4) (+) and PO(4) (3-) concentrations had no effect on ethanol production. However, increased Na(+) concentration (171 mM) inhibited growth and ethanol production. Yeast extract (0.5 g l(-1)) and trace metals were necessary for growth of C. ragsdalei. CSL alone did not support growth and ethanol production. Nutrients limiting in CSL were trace metals, NH(4) (+) and reducing agent (Cys: cysteine sulfide). Supplementation of trace metals, NH(4) (+) and CyS to CSL (20 g l(-1), wet weight basis) yielded better growth and similar ethanol production as compared to control medium. Using 10 g l(-1), the nutritional limitation led to reduced ethanol production. Higher concentrations of CSL (50 and 100 g l(-1)) were inhibitory for cell growth and ethanol production. The CSL could replace yeast extract, vitamins and minerals (excluding NH(4) (+)). The optimized CSL medium produced 120 and 50 mM of ethanol and acetate, respectively. The CSL could provide as an inexpensive source of most of the nutrients required for the syngas fermentation, and thus could improve the economics of ethanol production from biomass derived synthesis gas by C. ragsdalei.

Teaching nutritional biochemistry: an experimental approach using yeast.

PubMed

Alonso, Manuel; Stella, Carlos A

2012-12-01

In this report, we present a practical approach to teaching several topics in nutrition to science students at the high school and college freshmen levels. This approach uses baker's yeast (Saccharomyces cerevisiae) as a biological system model. The diameters of yeast colonies, which vary according to the nutrients present in the medium, can be observed, compared, and used to teach metabolic requirements. The experiments described in this report show simple macroscopic evidence of submicroscopic nutritional events. This can serve as a useful base for an analogy of heterotrophic human cell nutrition.

Effect of carbon sources on the growth and ethanol production of native yeast Pichia kudriavzevii ITV-S42 isolated from sweet sorghum juice.

PubMed

Díaz-Nava, L E; Montes-Garcia, N; Domínguez, J M; Aguilar-Uscanga, M G

2017-07-01

The importance of non-Saccharomyces yeast species in fermentation processes is widely acknowledged. Within this group, Pichia kudriavzevii ITV-S42 yeast strain shows particularly desirable characteristics for ethanol production. Despite this fact, a thorough study of the metabolic and kinetic characteristics of this strain is currently unavailable. The aim of this work is to study the nutritional requirements of Pichia kudriavzevii ITV-S42 strain and the effect of different carbon sources on the growth and ethanol production. Results showed that glucose and fructose were both assimilated and fermented, achieving biomass and ethanol yields of 0.37 and 0.32 gg -1 , respectively. Glycerol was assimilated but not fermented; achieving a biomass yield of 0.88 gg -1 . Xylose and sucrose were not metabolized by the yeast strain. Finally, the use of a culture medium enriched with salts and yeast extract favored glucose consumption both for growth and ethanol production, improving ethanol tolerance reported for this genre (35 g L -1 ) to 90 g L -1 maximum ethanol concentration (over 100%). Furthermore Pichia kudriavzevii ITV-S42 maintained its fermentative capacity up to 200 g L -1 initial glucose, demonstrating that this yeast is osmotolerant.

Tolerance of budding yeast Saccharomyces cerevisiae to ultra high pressure

NASA Astrophysics Data System (ADS)

Shibata, M.; Torigoe, M.; Matsumoto, Y.; Yamamoto, M.; Takizawa, N.; Hada, Y.; Mori, Y.; Takarabe, K.; Ono, F.

2014-05-01

Our studies on the tolerance of plants and animals against very high pressure of several GPa have been extended to a smaller sized fungus, the budding yeast Saccharomyces cerevisiae. Several pieces of budding yeast (dry yeast) were sealed in a small teflon capsule with a liquid pressure medium fluorinate, and exposed to 7.5 GPa by using a cubic anvil press. The pressure was kept constant for various duration of time from 2 to 24 h. After the pressure was released, the specimens were brought out from the teflon capsule, and they were cultivated on a potato dextrose agar. It was found that the budding yeast exposed to 7.5 GPa for up to 6 h showed multiplication. However, those exposed to 7.5 GPa for longer than 12 h were found dead. The high pressure tolerance of budding yeast is a little weaker than that of tardigrades.

Extraction of quasi-straightforward-propagating photons from diffused light transmitting through a scattering medium by polarization modulation

NASA Astrophysics Data System (ADS)

Horinaka, Hiromichi; Hashimoto, Koji; Wada, Kenji; Cho, Yoshio; Osawa, Masahiko

1995-07-01

The utilization of light polarization is proposed to extract quasi-straightforward-propagating photons from diffused light transmitting through a scattering medium under continuously operating conditions. Removal of a floor level normally appearing on the dynamic range over which the extraction capability is maintained is demonstrated. By use of pulse-based observations this cw scheme of extraction of quasi-straightforward-propagating photons is directly shown to be equivalent to the use of a temporal gate in the pulse-based operation.

Yeast and Mammalian Metallothioneins Functionally Substitute for Yeast Copper-Zinc Superoxide Dismutase

NASA Astrophysics Data System (ADS)

Tamai, Katherine T.; Gralla, Edith B.; Ellerby, Lisa M.; Valentine, Joan S.; Thiele, Dennis J.

1993-09-01

Copper-zinc superoxide dismutase catalyzes the disproportionation of superoxide anion to hydrogen peroxide and dioxygen and is thought to play an important role in protecting cells from oxygen toxicity. Saccharomyces cerevisiae strains lacking copper-zinc superoxide dismutase, which is encoded by the SOD1 gene, are sensitive to oxidative stress and exhibit a variety of growth defects including hypersensitivity to dioxygen and to superoxide-generating drugs such as paraquat. We have found that in addition to these known phenotypes, SOD1-deletion strains fail to grow on agar containing the respiratory carbon source lactate. We demonstrate here that expression of the yeast or monkey metallothionein proteins in the presence of copper suppresses the lactate growth defect and some other phenotypes associated with SOD1-deletion strains, indicating that copper metallothioneins substitute for copper-zinc superoxide dismutase in vivo to protect cells from oxygen toxicity. Consistent with these results, we show that yeast metallothionein mRNA levels are dramatically elevated under conditions of oxidative stress. Furthermore, in vitro assays demonstrate that yeast metallothionein, purified or from whole-cell extracts, exhibits copper-dependent antioxidant activity. Taken together, these data suggest that both yeast and mammalian metallothioneins may play a direct role in the cellular defense against oxidative stress by functioning as antioxidants.

Efficient production of flavonoids in Fagopyrum tataricum hairy root cultures with yeast polysaccharide elicitation and medium renewal process

PubMed Central

Zhao, Jiang-Lin; Zou, Liang; Zhang, Cai-Qiong; Li, Yuan-Yuan; Peng, Lian-Xin; Xiang, Da-Bing; Zhao, Gang

2014-01-01

Background: Tartary buckwheat (Fagopyrum tataricum), an excellent edible and medicinal crop, has been widely used as a daily diet and traditional medicine for a long time. The major functional components of Fagopyrum tataricum have been demonstrated to be flavonoids (i.e. rutin and quercetin), which had notable andioxidant, antidiabetic, hypocholesterolemic and antitumor activities. Hairy root culture is a convenient and efficient plant tissue culture system for large scale production of bioactive metabolites. Objective: To enhance the functional flavonoids production in hairy root culture of F. tataricum. Materials and Methods: The elicitation treatment in combination with medium renewal strategy was applied for efficient promoting flavonoids production in F. tataricum hairy root cultures. Results: The exogenous yeast polysaccharide (YPS) elicitor notably stimulated the functional metabolites production in F. tataricum hairy root cultures, and the stimulation effect was concentration-dependent. Combination with the YPS elicitation (200 mg/L) and medium renewal process, the maximal flavonoids yield was enhanced to 47.13 mg/L, about 3.2-fold in comparison with the control culture of 14.88 mg/L. Moreover, this research also revealed the accumulation of these bioactive metabolites resulted from the stimulation of the phenylpropanoid pathway by YPS treatment. These results indicated that the F. tataricum hairy root culture could be an effective system for rutin and quercetin production. PMID:25210309

Independent and additive effects of glutamic acid and methionine on yeast longevity.

PubMed

Wu, Ziyun; Song, Lixia; Liu, Shao Quan; Huang, Dejian

2013-01-01

It is established that glucose restriction extends yeast chronological and replicative lifespan, but little is known about the influence of amino acids on yeast lifespan, although some amino acids were reported to delay aging in rodents. Here we show that amino acid composition greatly alters yeast chronological lifespan. We found that non-essential amino acids (to yeast) methionine and glutamic acid had the most significant impact on yeast chronological lifespan extension, restriction of methionine and/or increase of glutamic acid led to longevity that was not the result of low acetic acid production and acidification in aging media. Remarkably, low methionine, high glutamic acid and glucose restriction additively and independently extended yeast lifespan, which could not be further extended by buffering the medium (pH 6.0). Our preliminary findings using yeasts with gene deletion demonstrate that glutamic acid addition, methionine and glucose restriction prompt yeast longevity through distinct mechanisms. This study may help to fill a gap in yeast model for the fast developing view that nutrient balance is a critical factor to extend lifespan.

Independent and Additive Effects of Glutamic Acid and Methionine on Yeast Longevity

PubMed Central

Wu, Ziyun; Song, Lixia; Liu, Shao Quan; Huang, Dejian

2013-01-01

It is established that glucose restriction extends yeast chronological and replicative lifespan, but little is known about the influence of amino acids on yeast lifespan, although some amino acids were reported to delay aging in rodents. Here we show that amino acid composition greatly alters yeast chronological lifespan. We found that non-essential amino acids (to yeast) methionine and glutamic acid had the most significant impact on yeast chronological lifespan extension, restriction of methionine and/or increase of glutamic acid led to longevity that was not the result of low acetic acid production and acidification in aging media. Remarkably, low methionine, high glutamic acid and glucose restriction additively and independently extended yeast lifespan, which could not be further extended by buffering the medium (pH 6.0). Our preliminary findings using yeasts with gene deletion demonstrate that glutamic acid addition, methionine and glucose restriction prompt yeast longevity through distinct mechanisms. This study may help to fill a gap in yeast model for the fast developing view that nutrient balance is a critical factor to extend lifespan. PMID:24244480

Effects of yeasts and bacteria on the levels of folates in rye sourdoughs.

PubMed

Kariluoto, Susanna; Aittamaa, Marja; Korhola, Matti; Salovaara, Hannu; Vahteristo, Liisa; Piironen, Vieno

2006-02-01

Fermentation of rye dough is often accompanied with an increase in folate content. In this study, three sourdough yeasts, Candida milleri CBS 8195, Saccharomyces cerevisiae TS 146, and Torulaspora delbrueckii TS 207; a control, baker's yeast S. cerevisiae ALKO 743; and four Lactobacillus spp., L. acidophilus TSB 262, L. brevis TSB 307, L. plantarum TSB 304, and L. sanfranciscensis TSB 299 originally isolated from rye sourdough were examined for their abilities to produce or consume folates. The microorganisms were grown in yeast extract-peptone-d-glucose medium as well as in small-scale fermentations that modelled the sourdough fermentation step used in rye baking. Total folate contents were determined using Lactobacillus rhamnosus (ATCC 7469) as the growth indicator organism. The microorganisms studied did not excrete folates into the media in significant amounts. Yeasts increased the folate contents of sterilised rye flour-water mixtures from 6.5 microg/100 g to between 15 and 23 microg/100 g after 19-h fermentation, whereas lactic acid bacteria decreased it to between 2.9 and 4.2 microg/100 g. Strains of Lactobacillus bulgaricus, L. casei, L. curvatus, L. fermentum, L. helveticus, Pediococcus spp., and Streptococcus thermophilus that were also tested gave folate contents after fermentation that varied between 2 and 10.4 microg/100 g. Although the four Lactobacillus spp. from sourdough consumed folates their effect on folate contents in co-cultivations was minimal. It was concluded that the increase of folate content during fermentation was mainly due to folate synthesis by yeasts. Fermentation of non-sterilised flour-water mixtures as such resulted in three-fold increases in the folate contents. Two folate producing bacteria were isolated from the non-sterilised flour and identified as Enterobacter cowanii and Pantoea agglomerans.

A comparative study on the potential of epiphytic yeasts isolated from tropical fruits to produce flavoring compounds.

PubMed

Grondin, Eric; Shum Cheong Sing, Alain; Caro, Yanis; Raherimandimby, Marson; Randrianierenana, Ando Lalaniaina; James, Steve; Nueno-Palop, Carmen; François, Jean Marie; Petit, Thomas

2015-06-16

In recent years, there has been an increasing interest in identifying and characterizing the yeast flora associated with diverse types of habitat because of the many potential desirable technological properties of these microorganisms, especially in food applications. In this study, a total of 101 yeast strains were isolated from the skins of tropical fruits collected in several locations in the South West Indian Ocean. Sequence analysis of the D1/D2 domains of the large subunit (LSU) ribosomal RNA gene identified 26 different species. Among them, two species isolated from the skins of Cape gooseberry and cocoa beans appeared to represent putative new yeast species, as their LSU D1/D2 sequence was only 97.1% and 97.4% identical to that of the yeasts Rhodotorula mucilaginosa and Candida pararugosa, respectively. A total of 52 Volatile Organic Compounds (VOCs) were detected by Head Space Solid Phase Micro Extraction coupled to Gas Chromatography and Mass Spectroscopy (HS-SPME-GC/MS) from the 26 yeast species cultivated on a glucose rich medium. Among these VOCs, 6 uncommon compounds were identified, namely ethyl but-2-enoate, ethyl 2-methylbut-2-enoate (ethyl tiglate), ethyl 3-methylbut-2-enoate, 2-methylpropyl 2-methylbut-2-enoate, butyl 2-methylbut-2-enoate and 3-methylbutyl 2-methylbut-2-enoate, making them possible yeast species-specific markers. In addition, statistical methods such as Principal Component Analysis allowed to associate each yeast species with a specific flavor profile. Among them, Saprochaete suaveolens (syn: Geotrichum fragrans) turned to be the best producer of flavor compounds, with a total of 32 out of the 52 identified VOCs in its flavor profile. Copyright © 2015 Elsevier B.V. All rights reserved.

Medium Optimization for the Production of Fibrinolytic Enzyme by Paenibacillus sp. IND8 Using Response Surface Methodology

PubMed Central

Prakash Vincent, Samuel Gnana

2014-01-01

Production of fibrinolytic enzyme by a newly isolated Paenibacillus sp. IND8 was optimized using wheat bran in solid state fermentation. A 25 full factorial design (first-order model) was applied to elucidate the key factors as moisture, pH, sucrose, yeast extract, and sodium dihydrogen phosphate. Statistical analysis of the results has shown that moisture, sucrose, and sodium dihydrogen phosphate have the most significant effects on fibrinolytic enzymes production (P < 0.05). Central composite design (CCD) was used to determine the optimal concentrations of these three components and the experimental results were fitted with a second-order polynomial model at 95% level (P < 0.05). Overall, 4.5-fold increase in fibrinolytic enzyme production was achieved in the optimized medium as compared with the unoptimized medium. PMID:24523635

Effects of a spoilage yeast from silage on in vitro ruminal fermentation.

PubMed

Santos, M C; Lock, A L; Mechor, G D; Kung, L

2015-04-01

Feeding silages with high concentrations of yeasts from aerobic spoilage is often implicated as a cause of poor animal performance on dairies. Our objective was to determine if a commonly found spoilage yeast, isolated from silage, had the potential to alter in vitro ruminal fermentations. A single colony of Issatchenkia orientalis, isolated from high-moisture corn, was grown in selective medium. The yeast culture was purified and added to in vitro culture tubes containing a total mixed ration (43% concentrate, 43% corn silage, 11% alfalfa haylage, and 3% alfalfa hay on a dry matter basis), buffer, and ruminal fluid to achieve added theoretical final concentrations of 0 (CTR), 4.40 (low yeast; LY), 6.40 (medium yeast; MY), and 8.40 (high yeast; HY) log10 cfu of yeast/mL of in vitro fluid. Seven separate tubes were prepared for each treatment and each time point and incubated for 12 and 24h at 39 °C. At the end of the incubation period, samples were analyzed for pH, yeast number, neutral detergent fiber (NDF) digestibility, volatile fatty acids (VFA), and fatty acids (FA). We found that total viable yeast counts decreased for all treatments in in vitro incubations but were still relatively high (5.3 log10 cfu of yeasts/mL) for HY after 24h of incubation. Addition of HY resulted in a lower pH and higher concentration of total VFA in culture fluid compared with other treatments. Moreover, additions of MY and HY decreased in vitro NDF digestibility compared with CTR, and the effect was greatest for HY. Overall, the biohydrogenation of dietary unsaturated FA was not altered by addition of I. orientalis and decreased over time with an increase in the accumulation of saturated FA, especially palmitic and stearic acids. We conclude that addition of I. orientalis, especially at high levels, has the potential to reduce in vitro NDF digestion and alter other aspects of ruminal fermentations. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All

Impact of new ingredients obtained from brewer's spent yeast on bread characteristics.

PubMed

Martins, Z E; Pinho, O; Ferreira, I M P L V O

2018-05-01

The impact of bread fortification with β-glucans and with proteins/proteolytic enzymes from brewers' spent yeast on physical characteristics was evaluated. β-Glucans extraction from spent yeast cell wall was optimized and the extract was incorporated on bread to obtain 2.02 g β-glucans/100 g flour, in order to comply with the European Food Safety Authority guidelines. Protein/proteolytic enzymes extract from spent yeast was added to bread at 60 U proteolytic activity/100 g flour. Both β-glucans rich and proteins/proteolytic enzymes extracts favoured browning of bread crust. However, breads with proteins/proteolytic enzymes addition presented lower specific volume, whereas the incorporation of β-glucans in bread lead to uniform pores that was also noticeble in terms of higher specific volume. Overall, the improvement of nutritional/health promoting properties is highlighted with β-glucan rich extract, not only due to bread β-glucan content but also for total dietary fibre content (39% increase). The improvement was less noticeable for proteins/proteolytic enzymes extract. Only a 6% increase in bread protein content was noted with the addition of this extract and higher protein content would most likely accentuate the negative impact on bread specific volume that in turn could impair consumer acceptance. Therefore, only β-glucan rich extract is a promising bread ingredient.

Mimicking lichens: incorporation of yeast strains together with sucrose-secreting cyanobacteria improves survival, growth, ROS removal, and lipid production in a stable mutualistic co-culture production platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Tingting; Li, Chien-Ting; Butler, Kirk

The feasibility of heterotrophic-phototrophic symbioses was tested via pairing of yeast strains Cryptococcus curvatus, Rhodotorula glutinis, or Saccharomyces cerevisiae with a sucrose-secreting cyanobacterium Synechococcus elongatus. The phototroph S. elongatus showed no growth in standard BG-11 medium with yeast extract, but grew well in BG-11 medium alone or supplemented with yeast nitrogen base without amino acids (YNB w/o aa). Among three yeast species, C. curvatus and R. glutinis adapted well to the BG-11 medium supplemented with YNB w/o aa, sucrose, and various concentrations of NaCl needed to maintain sucrose secretion from S. elongatus, while growth of S. cerevisiae was highly dependentmore » on sucrose levels. R. glutinis and C. curvatus grew efficiently and utilized sucrose produced by the partner in co-culture. Co-cultures of S. elongatus and R. glutinis were sustained over 1 month in both batch and in semi-continuous culture, with the final biomass and overall lipid yields in the batch co-culture 40 to 60% higher compared to batch mono-cultures of S. elongatus. The co-cultures showed enhanced levels of palmitoleic and linoleic acids. Furthermore, cyanobacterial growth in co-culture with R. glutinis was significantly superior to axenic growth, as S. elongatus was unable to grow in the absence of the yeast partner when cultivated at lower densities in liquid medium. Accumulated reactive oxygen species was observed to severely inhibit axenic growth of cyanobacteria, which was efficiently alleviated through catalase supply and even more effectively with co-cultures of R. glutinis. In conclusion, the pairing of a cyanobacterium and eukaryotic heterotroph in the artificial lichen of this study demonstrates the importance of mutual interactions between phototrophs and heterotrophs, e.g., phototrophs provide a carbon source to heterotrophs, and heterotrophs assist phototrophic growth and survival by removing/eliminating oxidative stress. Our results establish

Mimicking lichens: incorporation of yeast strains together with sucrose-secreting cyanobacteria improves survival, growth, ROS removal, and lipid production in a stable mutualistic co-culture production platform

DOE PAGES

Li, Tingting; Li, Chien-Ting; Butler, Kirk; ...

2017-03-21

The feasibility of heterotrophic-phototrophic symbioses was tested via pairing of yeast strains Cryptococcus curvatus, Rhodotorula glutinis, or Saccharomyces cerevisiae with a sucrose-secreting cyanobacterium Synechococcus elongatus. The phototroph S. elongatus showed no growth in standard BG-11 medium with yeast extract, but grew well in BG-11 medium alone or supplemented with yeast nitrogen base without amino acids (YNB w/o aa). Among three yeast species, C. curvatus and R. glutinis adapted well to the BG-11 medium supplemented with YNB w/o aa, sucrose, and various concentrations of NaCl needed to maintain sucrose secretion from S. elongatus, while growth of S. cerevisiae was highly dependentmore » on sucrose levels. R. glutinis and C. curvatus grew efficiently and utilized sucrose produced by the partner in co-culture. Co-cultures of S. elongatus and R. glutinis were sustained over 1 month in both batch and in semi-continuous culture, with the final biomass and overall lipid yields in the batch co-culture 40 to 60% higher compared to batch mono-cultures of S. elongatus. The co-cultures showed enhanced levels of palmitoleic and linoleic acids. Furthermore, cyanobacterial growth in co-culture with R. glutinis was significantly superior to axenic growth, as S. elongatus was unable to grow in the absence of the yeast partner when cultivated at lower densities in liquid medium. Accumulated reactive oxygen species was observed to severely inhibit axenic growth of cyanobacteria, which was efficiently alleviated through catalase supply and even more effectively with co-cultures of R. glutinis. In conclusion, the pairing of a cyanobacterium and eukaryotic heterotroph in the artificial lichen of this study demonstrates the importance of mutual interactions between phototrophs and heterotrophs, e.g., phototrophs provide a carbon source to heterotrophs, and heterotrophs assist phototrophic growth and survival by removing/eliminating oxidative stress. Our results establish

Conditions of activation of yeast plasma membrane ATPase.

PubMed

Sychrová, H; Kotyk, A

1985-04-08

The in vivo activation of the H+-ATPase of baker's yeast plasma membrane found by Serrano in 1983 was demonstrated with D-glucose aerobically and anaerobically (as well as in a respiration-deficient mutant) and, after suitable induction, with maltose, trehalose, and galactose. The activated but not the control ATPase was sensitive to oligomycin. No activation was possible in a cell-free extract with added glucose. The ATPase was not activated in yeast protoplasts which may account for the absence of glucose-stimulated secondary active transports in these wall-less cells and provide support for a microscopic coupling between ATPase activity and these transports in yeast cells.

Effects of different extracts of Eucalyptus camaldulensis on Trichomonas vaginalis parasite in culture medium

PubMed Central

Hassani, Solmaz; Asghari, Gholamreza; Yousefi, Hossseinali; Kazemian, Afsaneh; Rafieiean, Mahmood; Darani, Hossein Yousofi

2013-01-01

Background: Trichomonas vaginalis is considered one of the main causes of vulvovaginitis in women. Metronidazole with vast side effects is now the drug of choice for treatment of this infection. In an attempt to find an alternative drug, the effect of Eucalyptus camaldulensis on this parasite was shown in previous studies. In this investigation, the effect of different extracts of this plant on T. vaginalis in culture medium has been investigated. Materials and Methods: Five different extracts including total extract, diethyl ether, chloroform, ethyl acetate, and water fractions were prepared. The extracts were dried using vacuum rotary evaporator and then they were used for in vitro anti-trichomonas experiments. Results: Crude extract of E. camaldulensis showed 80% growth inhibition (GI) in a concentration of 12.5 mg/ml during 24 h. Diethyl ether extract in a concentration of 25 mg/ml showed 100% GI during 24 h. With ethyl acetate extract, 100% GI was detected with the minimum concentration of 12.5 mg/ml in the first 24 h. Finally, water extract in a concentration of 50 mg/ml showed 80% and 100% GI after 48 and 72 h, respectively. Conclusion: Ethyl acetate fraction is the extract which showed the highest percentage of GI (100%) with the least concentration (12.5 mg/ml) after 24 and 48 h. PMID:24516847

[Detection of viable metabolically active yeast cells using a colorimetric assay].

PubMed

Růzicka, F; Holá, V

2008-02-01

The increasing concern of yeasts able to form biofilm brings about the need for susceptibility testing of both planktonic and biofilm cells. Detection of viability or metabolic activity of yeast cells after exposure to antimicrobials plays a key role in the assessment of susceptibility testing results. Colorimetric assays based on the color change of the medium in the presence of metabolically active cells proved suitable for this purpose. In this study, the usability of a colorimetric assay with the resazurin redox indicator for monitoring the effect of yeast inoculum density on the reduction rate was tested. As correlation between the color change rate and inoculum density was observed, approximate quantification of viable cells was possible. The assay would be of relevance to antifungal susceptibility testing in both planktonic and biofilm yeasts.

Evaluation of Brewer's spent yeast to produce flavor enhancer nucleotides: influence of serial repitching.

PubMed

Vieira, Elsa; Brandão, Tiago; Ferreira, Isabel M P L V O

2013-09-18

The present work evaluates the influence of serial yeast repitching on nucleotide composition of brewer's spent yeast extracts produced without addition of exogenous enzymes. Two procedures for disrupting cell walls were compared, and the conditions for low-cost and efficient RNA hydrolysis were selected. A HILIC methodology was validated for the quantification of nucleotides and nucleosides in yeast extracts. Thirty-seven samples of brewer's spent yeast ( Saccharomyces pastorianus ) organized according to the number of serial repitchings were analyzed. Nucleotides accounted for 71.1-88.2% of the RNA products; 2'AMP was the most abundant (ranging between 0.08 and 2.89 g/100 g dry yeast). 5'GMP content ranged between 0.082 and 0.907 g/100 g dry yeast. The sum of 5'GMP, 5'IMP, and 5'AMP represented between 25 and 32% of total nucleotides. This works highlights for the first time that although serial repitching influences the content of monophosphate nucleotides and nucleosides, the profiles of these RNA hydrolysis products are not affected.

The extraction and purification of a cysteine transfer ribonucleic acid from baker's yeast.

PubMed Central

Holness, N J; Atfield, G

1976-01-01

1. A modification of the RPC 1 system of A.D. Kelmers, G.D. Novelli & M.P. Stulberg (1965) (J. Biol. Chem. 240, 3979-3983) is described in which the support medium is a Celite of narrow range particle size treated with dichlorodimethylsilane. 2. By using this system an apparently pure preparation of tRNA Cys was isolated from baker's yeast tRNA. 3. This preparation accepted at least 60% of the theoretical quantity of [3-14C]cysteine in a conventional assay and failed to accept isoleucine, phenylalanine, proline, serine or tyrosine. 4. A theoretical countercurrent-distribution curve calculated by assuming a distribution coefficient K of 2.03 was in excellent agreement with the profiles of E260 and cysteine-acceptor ability after 537 transfers in the 1.85 M-phosphate/formamide/propan-2-ol system of C.M. Connelly & B.P. Doctor (1965) (J. Biol. Chem. 241, 715-719). 5. Chromatography of tRNA Cys on Bio-Gel P100 polyacrylamide beads afforded two components one of which was far less efficient than the other in accepting cysteine. The base compositions of the two were similar. PMID:776175

Drying enhances immunoactivity of spent brewer's yeast cell wall β-D-glucans.

PubMed

Liepins, Janis; Kovačova, Elena; Shvirksts, Karlis; Grube, Mara; Rapoport, Alexander; Kogan, Grigorij

2015-07-20

Due to immunological activity, microbial cell wall polysaccharides are defined as 'biological response modifiers' (BRM). Cell walls of spent brewer's yeast also have some BRM activity. However, up to date there is no consensus on the use of spent brewer's yeast D-glucan as specific BRM in humans or animals. The aim of this paper is to demonstrate the potential of spent brewer's yeast β-D-glucans as BRM, and drying as an efficient pretreatment to increase β-D-glucan's immunogenic activity. Our results revealed that drying does not change spent brewer's yeast biomass carbohydrate content as well as the chemical structure of purified β-D-glucan. However, drying increased purified β-D-glucan TNF-α induction activity in the murine macrophage model. We presume drying pretreatment enhances purity of extracted β-D-glucan. This is corroborated with FT-IR analyses of the β-D-glucan spectra. Based on our results, we suggest that dry spent brewer's yeast biomass can be used as a cheap source for high-quality β-D-glucan extraction. Drying in combination with carboxylmethylation (CM), endows spent brewer's yeast β-D-glucan with the immunoactivity similar or exceeding that of a well-characterized fungal BRM pleuran. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of carbon source on the accumulation of cytochrome P-450 in the yeast Saccharomyces cerevisiae.

PubMed

Kärenlampi, S O; Marin, E; Hänninen, O O

1981-02-15

The appearance of cytochrome P-450 in the yeast Saccharomyces cerevisiae depended on the substrate supporting growth. Cytochrome P-450 was apparent in yeast cells grown on a strongly fermentable sugar such as D-glucose, D-fructose or sucrose. When yeast was grown on D-galactose, D-mannose or maltose, where fermentation and respiration occurred concomitantly, cytochrome P-450 was also formed. The cytochrome P-450 concentration was maximal at the beginning of the stationary phase of the culture. Thereafter the concentration decreased, reaching zero at a late-stationary phase. When the yeast was grown on a medium that contained lactose or pentoses (L-arabinose, L-rhamnose, D-ribose and D-xylose), cytochrome P-450 did not occur. When a non-fermentable energy source (glycerol, lactate or ethanol) was used, no cytochrome P-450 was detectable. Transfer of cells from D-glucose medium to ethanol medium caused a slow disappearance of cytochrome P-450, although the amount of the haemoprotein still continued to increase in the control cultures. Cytochrome P-450 appeared thus to accumulate in conditions where the rate of growth was fast and fermentation occurred. Occurrence of this haemoprotein is not necessarily linked, however, with the repression of mitochondrial haemoprotein synthesis.

Alcohol production from Jerusalem artichoke using yeasts with inulinase activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guiraud, J.P.; Daurelles, J.; Galzy, P.

1981-07-01

The purpose of this article is to show that yeasts with inulinase activity can be used to produce ethanol from the Jerusalem artichoke (Helianthus tuberosus L.). The results show that a fermentable extract can be easily obtained from the Jerusalem artichoke even under cold conditions. Yeasts with inulinase activity can be used to produce ethanol with good profitability. 19 refs.

The Fermentative and Aromatic Ability of Kloeckera and Hanseniaspora Yeasts

NASA Astrophysics Data System (ADS)

Díaz-Montaño, Dulce M.; de Jesús Ramírez Córdova, J.

Spontaneous alcoholic fermentation from grape, agave and others musts into an alcoholic beverage is usually characterized by the presence of several non-Saccharomyces yeasts. These genera yeasts are dominant in the early stages of the alcoholic fermentation. However the genera Hanseniaspora and Kloeckera may survive at a significant level during fermentation and can influence the chemical composition of the beverage. Several strains belonging to the species Kloeckera api-culata and Hanseniaspora guilliermondii have been extensively studied in relation to the formation of some metabolic compounds affecting the bouquet of the final product. Indeed some apiculate yeast showed positive oenological properties and their use in the alcoholic fermentations has been suggested to enhance the aroma and flavor profiles. The non- Saccharomyces yeasts have the capability to produce and secrete enzymes in the medium, such as β -glucosidases, which release monoterpenes derived from their glycosylated form. These compounds contribute to the higher fruit-like characteristic of final product. This chapter reviews metabolic activity of Kloeckera and Hanseniaspora yeasts in several aspects: fermentative capability, aromatic compounds production and transformation of aromatic precursor present in the must, also covers the molecular methods for identifying of the yeast

A multiplex culture system for the long-term growth of fission yeast cells.

PubMed

Callens, Céline; Coelho, Nelson C; Miller, Aaron W; Sananes, Maria Rosa Domingo; Dunham, Maitreya J; Denoual, Matthieu; Coudreuse, Damien

2017-08-01

Maintenance of long-term cultures of yeast cells is central to a broad range of investigations, from metabolic studies to laboratory evolution assays. However, repeated dilutions of batch cultures lead to variations in medium composition, with implications for cell physiology. In Saccharomyces cerevisiae, powerful miniaturized chemostat setups, or ministat arrays, have been shown to allow for constant dilution of multiple independent cultures. Here we set out to adapt these arrays for continuous culture of a morphologically and physiologically distinct yeast, the fission yeast Schizosaccharomyces pombe, with the goal of maintaining constant population density over time. First, we demonstrated that the original ministats are incompatible with growing fission yeast for more than a few generations, prompting us to modify different aspects of the system design. Next, we identified critical parameters for sustaining unbiased vegetative growth in these conditions. This requires deletion of the gsf2 flocculin-encoding gene, along with addition of galactose to the medium and lowering of the culture temperature. Importantly, we improved the flexibility of the ministats by developing a piezo-pump module for the independent regulation of the dilution rate of each culture. This made it possible to easily grow strains that have different generation times in the same assay. Our system therefore allows for maintaining multiple fission yeast cultures in exponential growth, adapting the dilution of each culture over time to keep constant population density for hundreds of generations. These multiplex culture systems open the door to a new range of long-term experiments using this model organism. © 2017 The Authors. Yeast published by John Wiley & Sons, Ltd. © 2017 The Authors. Yeast published by John Wiley & Sons, Ltd.

Interaction of media on production and biocontrol efficacy of Pseudomonas fluorescens and Bacillus subtilis against grey mould of apple.

PubMed

Peighamy-Ashnaei, S; Sharifi-Tehrani, A; Ahmadzadeh, M; Behboudi, K

2008-01-01

The medium has a profound effect on biocontrol agents, including ability to grow and effectiveness in disease control. In this study, growth and antagonistic efficacy of strains P-5 and P-35 (P. fluorescens), B-3 and B-16 (B. subtilis) were evaluated in combinations of two carbon (sucrose and molasses) and two nitrogen (urea and yeast extract) sources to optimize control of Botrytis cinerea on apple. All of the strains were grown in different liquid media (pH = 6.9) including: sucrose + yeast extract, molasses of sugar beet + yeast extract in 2:1 and 1:1 w/w ratios, molasses of sugar beet + urea, molasses, malt extract and nutrient broth. Apples (Golden Delicious) were inoculated by a 25-microl suspension of 10(6) spores of B. cinerea per ml, wounding each fruit (in two sites separately). Then a 25-microl suspension of each strain, containing 2 x 10(8) cfu ml(-1) grown in each of the above culture media, was applied to each wound. Results indicated that Molasses + Yeast extract (1:1 w/w) medium supported rapid growth in all of the strains. The final growth of B. subtilis B-16 in Molasses + Yeast extract (1:1 w/w) medium was 5 x 10(9) cfu ml(-1). After ten days, all of the strains significantly inhibited pathogenicity of B. cinerea on apples. The biocontrol efficacy of B. subtilis B-3 in Molasses + Yeast extract (1:1 w/w) medium reduced the severity of grey mould from 100% (inoculated control) to less than 26.9%. After 20 days, Strain B-3 showed a considerable biocontrol efficacy in Molasses medium and reduced the severity of grey mould from 100% (inoculated control) to less than 38.2%. The results obtained in this study could be used to provide a reliable basis for the increase of population of biocontrol agents in fermentation process.

Interactions between Brettanomyces bruxellensis and other yeast species during the initial stages of winemaking.

PubMed

Renouf, V; Falcou, M; Miot-Sertier, C; Perello, M C; De Revel, G; Lonvaud-Funel, A

2006-06-01

Wine is the product of complex interactions between yeasts and bacteria in grape must. Amongst yeast populations, two groups can be distinguished. The first, named non-Saccharomyces (NS), colonizes, with many other micro-organisms, the surface of grape berries. In the past, NS yeasts were primarily considered as spoilage micro-organisms. However, recent studies have established a positive contribution of certain NS yeasts to wine quality. Amongst the group of NS yeasts, Brettanomyces bruxellensis, which is not prevalent on wine grapes, plays an important part in the evolution of wine aroma. Some of their secondary metabolites, namely volatile phenols, are responsible for wine spoilage. The other group contributing to wine aroma, which is also the main agent of alcoholic fermentation (AF), is composed of Saccharomyces species. The fermenting must is a complex microbial ecosystem where numerous yeast strains grow and die according to their adaptation to the medium. Yeast-yeast interactions occur during winemaking right from the onset of AF. The aim of this study was to describe the interactions between B. bruxellensis, other NS and Saccharomyces cerevisiae during laboratory and practical scale winemaking. Molecular methods such as internal transcribed spacer-restriction fragment length polymorphism and polymerase chain reaction and denaturing gradient gel electrophoresis were used in laboratory scale experiments and cellar observations. The influence of different oenological practices, like the level of sulphiting at harvest time, cold maceration preceding AF, addition of commercial active dry yeasts on B. bruxellensis and other yeast interactions and their evolution during the initial stages of winemaking have been studied. Brettanomyces bruxellensis was the most adapted NS yeast at the beginning of AF, and towards the end of AF it appeared to be more resistant than S. cerevisiae to the conditions of increased alcohol and sugar limitation. Among all NS yeast species

Chiral speciation and determination of selenomethionine enantiomers in selenized yeast by ligand-exchange micellar electrokinetic capillary chromatography after solid phase extraction.

PubMed

Duan, Jiankun; He, Man; Hu, Bin

2012-12-14

A new phenylalanine derivative (L-N-(2-hydroxy-propyl)-phenylalanine, L-HP-Phe) was synthesized and its chelate with Cu(II) (Cu(II)-(L-HP-Phe)(2)) was used as the chiral selector for the ligand-exchange (LE) chiral separation of D,L-selenomethionine (SeMet) in selenized yeast samples by micelle electrokinetic capillary chromatography (MEKC). In order to improve the sensitivity of MEKC-UV, two-step preconcentration strategy was employed, off-line solid phase extraction (SPE) and on-line large volume sample stacking (LVSS). D,L-SeMet was first retained on the Cu(II) loaded mesoporous TiO(2), then eluted by 0.1 mL of 5 mol L(-1) ammonia, and finally introduced for MEKC-UV analysis by LVSS injection after evaporation of NH(3). With the enrichment factors of 1400 and 1378, the LODs of 0.44 and 0.60 ng mL(-1) for L-SeMet and D-SeMet was obtained, respectively. The developed method was applied to the analysis of D,L-SeMet in a certified reference material of SELM-1 and a commercial nutrition yeast, and the results showed that most of SeMet in the SELM-1 selenized yeast was l isomer and the recovery for L and D isomers in the spiked commercial nutrition yeast was 96.3% and 103%, respectively. This method is featured with low running cost, high sensitivity and selectivity, and exhibits application potential in chiral analysis of seleno amino acids in real world samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Production of fermentation aroma compounds by Saccharomyces cerevisiae wine yeasts: effects of yeast assimilable nitrogen on two model strains.

PubMed

Carrau, Francisco M; Medina, Karina; Farina, Laura; Boido, Eduardo; Henschke, Paul A; Dellacassa, Eduardo

2008-11-01

The contribution of yeast fermentation metabolites to the aromatic profile of wine is well documented; however, the biotechnological application of this knowledge, apart from strain selection, is still rather limited and often contradictory. Understanding and modeling the relationship between nutrient availability and the production of desirable aroma compounds by different strains must be one of the main objectives in the selection of industrial yeasts for the beverage and food industry. In order to overcome the variability in the composition of grape juices, we have used a chemically defined model medium for studying yeast physiological behavior and metabolite production in response to nitrogen supplementation so as to identify an appropriate yeast assimilable nitrogen level for strain differentiation. At low initial nitrogen concentrations, strain KU1 produced higher quantities of esters and fatty acids whereas M522 produced higher concentrations of isoacids, gamma-butyrolactone, higher alcohols and 3-methylthio-1-propanol. We propose that although strains KU1 and M522 have a similar nitrogen consumption profile, they represent useful models for the chemical characterization of wine strains in relation to wine quality. The differential production of aroma compounds by the two strains is discussed in relation to their capacity for nitrogen usage and their impact on winemaking. The results obtained here will help to develop targeted metabolic footprinting methods for the discrimination of industrial yeasts.

The impact of culture medium on the development and physiology of biofilms of Pseudomonas fluorescens formed on polyurethane paint.

PubMed

Crookes-Goodson, Wendy J; Bojanowski, Caitlin L; Kay, Michelle L; Lloyd, Pamela F; Blankemeier, Andrew; Hurtubise, Jennifer M; Singh, Kristi M; Barlow, Daniel E; Ladouceur, Harold D; Matt Eby, D; Johnson, Glenn R; Mirau, Peter A; Pehrsson, Pehr E; Fraser, Hamish L; Russell, John N

2013-01-01

Microbial biofilms cause the deterioration of polymeric coatings such as polyurethanes (PUs). In many cases, microbes have been shown to use the PU as a nutrient source. The interaction between biofilms and nutritive substrata is complex, since both the medium and the substratum can provide nutrients that affect biofilm formation and biodeterioration. Historically, studies of PU biodeterioration have monitored the planktonic cells in the medium surrounding the material, not the biofilm. This study monitored planktonic and biofilm cell counts, and biofilm morphology, in long-term growth experiments conducted with Pseudomonas fluorescens under different nutrient conditions. Nutrients affected planktonic and biofilm cell numbers differently, and neither was representative of the system as a whole. Microscopic examination of the biofilm revealed the presence of intracellular storage granules in biofilms grown in M9 but not yeast extract salts medium. These granules are indicative of nutrient limitation and/or entry into stationary phase, which may impact the biodegradative capability of the biofilm.

Concentration-Dependent Effects of Rhodiola Rosea on Long-Term Survival and Stress Resistance of Yeast Saccharomyces Cerevisiae: The Involvement of YAP 1 and MSN2/4 Regulatory Proteins

PubMed Central

Bayliak, Maria M.; Burdyliuk, Nadia I.; Izers’ka, Lilia I.; Lushchak, Volodymyr I.

2014-01-01

Concentration-dependent effects of aqueous extract from R. rosea root on long-term survival and stress resistance of budding yeast Saccharomyces cerevisiae were studied. At low concentrations, R. rosea aqueous extract extended yeast chronological lifespan, enhanced oxidative stress resistance of stationary-phase cells and resistance to number stressors in exponentially growing cultures. At high concentrations, R. rosea extract sensitized yeast cells to stresses and shortened yeast lifespan. These biphasic concentration-responses describe a common hormetic phenomenon characterized by a low-dose stimulation and a high-dose inhibition. Yeast pretreatment with low doses of R. rosea extract enhanced yeast survival and prevented protein oxidation under H2O2-induced oxidative stress. Positive effect of R. rosea extract on yeast survival under heat shock exposure was not accompanied with changes in antioxidant enzyme activities and levels of oxidized proteins. The deficiency in transcriptional regulators, Msn2/Msn4 and Yap1, abolished the positive effect of low doses of R. rosea extract on yeast viability under stress challenges. Potential involvement of Msn2/Msn4 and Yap1 regulatory proteins in realization of R. rosea beneficial effects is discussed. PMID:24659935

A simplified radiometabolite analysis procedure for PET radioligands using a solid phase extraction with micellar medium.

PubMed

Nakao, Ryuji; Halldin, Christer

2013-07-01

A solid phase extraction method has been developed for simple and high-speed direct determination of PET radioligands in plasma. This methodology makes use of a micellar medium and a solid-phase extraction cartridge for displacement of plasma protein bound radioligand and separation of PET radioligands from their radiometabolites without significant preparation. The plasma samples taken from monkey or human during PET measurements were mixed with a micellar eluent containing an anionic surfactant sodium dodecyl sulphate and loaded onto SPE cartridges. The amount of radioactivity corresponding to parent radioligand (retained on the cartridge) and its radioactive metabolites (eluted with micellar eluent) was measured. Under the optimized conditions, excellent separation of target PET radioligands from their radiometabolites was achieved with a single elution and short run-time of 1 min. This method was successfully applied to study the metabolism for (11)C-labelled radioligands in human or monkey plasma. The amount of parent PET radioligands estimated by micellar solid phase extraction strongly corresponded with that determined by radio-LC. The improved throughput permitted the analysis of a large number of plasma samples (up to 13 samples per one PET study) for accurate estimation of metabolite-corrected input function during quantitative PET imaging studies. Solid phase extraction together with micellar medium is fast, sensitive and easy to use, and therefore it is an attractive alternative method to determine relative composition of PET radioligands in plasma. Copyright © 2013 Elsevier Inc. All rights reserved.

Converting paper mill sludge into neutral lipids by oleaginous yeast Cryptococcus vishniaccii for biodiesel production.

PubMed

Deeba, Farha; Pruthi, Vikas; Negi, Yuvraj S

2016-08-01

Paper mill sludge (PMS) was assessed as cheap renewable lignocellulosic biomass for lipid production by the oleaginous yeast Cryptococcus vishniaccii (MTCC 232). The sonicated paper mill sludge extract (PMSE) exhibited enhanced lipid yield and lipid content 7.8±0.57g/l, 53.40% in comparison to 5.5±0.8g/l, 40.44% glucose synthetic medium, respectively. The accumulated triglycerides (TAG) inside the lipid droplets (LDs) were converted to biodiesel by transesterification and thoroughly characterized using GC-MS technique. The fatty acid methyl ester (FAME) profile obtained reveals elevated content of oleic acid followed by palmitic acid, linoleic acid and stearic acid with improved oxidative stability related to biodiesel quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

Isolated yeast promoter sequence and a method of regulated heterologous expression

DOEpatents

Gao, Johnway; Skeen, Rodney S.; Hooker, Brian S.; Anderson, Daniel B.

2005-05-31

The present invention provides the promoter clone discovery of a glucoamylase gene of a starch utilizing yeast strain Schwanniomyces castellii. The isolated glucoamylase promoter is an inducible promoter, which can regulate strong gene expression in starch culture medium.

Immobilisation increases yeast cells' resistance to dehydration-rehydration treatment.

PubMed

Borovikova, Diana; Rozenfelde, Linda; Pavlovska, Ilona; Rapoport, Alexander

2014-08-20

This study was performed with the goal of revealing if the dehydration procedure used in our new immobilisation method noticeably decreases the viability of yeast cells in immobilised preparations. Various yeasts were used in this research: Saccharomyces cerevisiae cells that were rather sensitive to dehydration and had been aerobically grown in an ethanol-containing medium, a recombinant strain of S. cerevisiae grown in aerobic conditions which were completely non-resistant to dehydration and an anaerobically grown bakers' yeast strain S. cerevisiae, as well as a fairly resistant Pichia pastoris strain. Experiments performed showed that immobilisation of all these strains essentially increased their resistance to a dehydration-rehydration treatment. The increase of cells' viability (compared with control cells dehydrated in similar conditions) was from 30 to 60%. It is concluded that a new immobilisation method, which includes a dehydration stage, does not lead to an essential loss of yeast cell viability. Correspondingly, there is no risk of losing the biotechnological activities of immobilised preparations. The possibility of producing dry, active yeast preparations is shown, for those strains that are very sensitive to dehydration and which can be used in biotechnology in an immobilised form. Finally, the immobilisation approach can be used for the development of efficient methods for the storage of recombinant yeast strains. Copyright © 2014 Elsevier B.V. All rights reserved.

Size and competitive mating success in the yeast Saccharomyces cerevisiae.

PubMed

Smith, Carl; Pomiankowski, Andrew; Greig, Duncan

2014-03-01

In unicellular organisms like yeast, mating with the right partner is critical to future fitness because each individual can only mate once. Because cell size is important for viability, mating with a partner of the right size could be a significant advantage. To investigate this idea, we manipulated the size of unmated yeast cells and showed that their viability depended on environmental conditions; large cells do better on rich medium and small cells do better on poor medium. We also found that the fitness of offspring is determined by the size of their parents. Finally, we demonstrated that when a focal cell of one mating type was placed with a large and a small cell of the opposite mating type, it was more likely to mate with the cell that was closer to the optimum size for growth in a given environment. This pattern was not generated by differences in passive mating efficiency of large and small cells across environments but by competitive mating behavior, mate preference, or both. We conclude that the most likely mechanism underlying this interesting behavior is that yeast cells compete for mates by producing pheromone signals advertising their viability, and cells with the opportunity to choose prefer to mate with stronger signalers because such matings produce more viable offspring.

Process Analysis of Variables for Standardization of Antifungal Susceptibility Testing of Nonfermentative Yeasts ▿

PubMed Central

Zaragoza, Oscar; Mesa-Arango, Ana C.; Gómez-López, Alicia; Bernal-Martínez, Leticia; Rodríguez-Tudela, Juan Luis; Cuenca-Estrella, Manuel

2011-01-01

Nonfermentative yeasts, such as Cryptococcus spp., have emerged as fungal pathogens during the last few years. However, standard methods to measure their antifungal susceptibility (antifungal susceptibility testing [AST]) are not completely reliable due to the impaired growth of these yeasts in standard media. In this work, we have compared the growth kinetics and the antifungal susceptibilities of representative species of nonfermentative yeasts such as Cryptococcus neoformans, Cryptococcus gattii, Cryptococcus albidus, Rhodotorula spp., Yarrowia lipolytica, Geotrichum spp., and Trichosporon spp. The effect of the growth medium (RPMI medium versus yeast nitrogen base [YNB]), glucose concentration (0.2% versus 2%), nitrogen source (ammonium sulfate), temperature (30°C versus 35°C), shaking, and inoculum size (103, 104, and 105 cells) were analyzed. The growth rate, lag phase, and maximum optical density were obtained from each growth experiment, and after multivariate analysis, YNB-based media demonstrated a significant improvement in the growth of yeasts. Shaking, an inoculum size of 105 CFU/ml, and incubation at 30°C also improved the growth kinetics of organisms. Supplementation with ammonium sulfate and with 2% glucose did not have any effect on growth. We also tested the antifungal susceptibilities of all the isolates by the reference methods of the CLSI and EUCAST, the EUCAST method with shaking, YNB under static conditions, and YNB with shaking. MIC values obtained under different conditions showed high percentages of agreement and significant correlation coefficient values between them. MIC value determinations according to CLSI and EUCAST standards were rather complicated, since more than half of isolates tested showed a limited growth index, hampering endpoint determinations. We conclude that AST conditions including YNB as an assay medium, agitation of the plates, reading after 48 h of incubation, an inoculum size of 105 CFU/ml, and incubation at 30�

Optimization of culturing condition and medium composition for the production of alginate lyase by a marine Vibrio sp. YKW-34

NASA Astrophysics Data System (ADS)

Fu, Xiaoting; Lin, Hong; Kim, Sang Moo

2008-02-01

Carbohydrases secreted by marine Vibrio sp. YKW-34 with strong Laminaria cell wall degrading ability were screened, and among them alginate lyase was found to be dominant. The effects of medium composition and culturing condition on the production of alginate lyase by marine Vibrio sp. YKW-34 in flask were investigated in this study. In the culture medium of marine broth, no alginate lyase was produced. The activity of the alginate lyase, after being induced, reached 5 UmL-1. The best inoculum volume and inoculum age were 10% and 12 h, respectively. The optimal temperature for alginate lyase production was 25°C. The fermentation medium was composed of 0.5% of Laminaria powder and 0.2% of KNO3 with an initial acidity of pH 8.0. Alginate could induce alginate lyase production but not as efficiently as Laminaria powder did. The addition of fucoidan, cellulose and glucose had negative effect on the alginate lyase production. Other kinds of nitrogen sources, such as yeast extract, beef extract and peptone, had positive effect on the growth of the microorganism and negative effect on alginate lyase production. In addition, the time course of alginate lyase production under the optimized condition was described. The optimal harvest time was 48 h.

Bioactivity studies of extracts from Tridax procumbens.

PubMed

Taddei, A; Rosas-Romero, A J

2000-06-01

An updated review on the biological activity of Tridax procumbens is presented. A detailed biological screening comprised of gram-positive and gram-negative bacteria, yeasts and fungi using crude extracts of this plant was undertaken. The n-hexane extract of the flowers showed activity against Escherichia coli. The same extract of the whole aerial parts was active against Mycobacterium smegmatis, Escherichia coli, Salmonella group C and Salmonella paratyphi. The ethyl-acetate extract of the flowers was active against Bacillus cereus and Klebsiella sp. The aerial parts extract also showed activity only against Mycobacterium smegmatis and Staphylococcus aureus, while the aqueous extract showed no antimicrobial activity. None of the tested extracts was active against the yeasts, Candida albicans, Candida tropicalis and Rhodotorula rubra; or the fungi: Aspergillus flavus, Aspergillus niger, Mucor sp. and Trichophyton rubrum.

Yeast identification in floral nectar of Mimulus aurantiacus (Invited)

NASA Astrophysics Data System (ADS)

Kyauk, C.; Belisle, M.; Fukami, T.

2009-12-01

Nectar is such a sugar-rich resource that serves as a natural habitat in which microbes thrive. As a result, yeasts arrive to nectar on the bodies of pollinators such as hummingbirds and bees. Yeasts use the sugar in nectar for their own needs when introduced. This research focuses on the identification of different types of yeast that are found in the nectar of Mimulus aurantiacus (commonly known as sticky monkey-flower). Unopened Mimulus aurantiacus flower buds were tagged at Jasper Ridge and bagged three days later. Floral nectar was then extracted and plated on potato dextrose agar. Colonies on the plates were isolated and DNA was extracted from each sample using QIAGEN DNeasy Plant Mini Kit. The DNA was amplified through PCR and ran through gel electrophoresis. The PCR product was used to clone the nectar samples into an E.coli vector. Finally, a phylogenetic tree was created by BLAST searching sequences in GenBank using the Internal Transcribed Space (ITS) locus. It was found that 18 of the 50 identified species were Candida magnifica, 14 was Candida rancensis, 6 were Crytococcus albidus and there were 3 or less of the following: Starmella bombicola, Candida floricola, Aureobasidium pullulans, Pichia kluyvera, Metschnikowa cibodaserisis, Rhodotorua colostri, and Malassezia globosa. The low diversity of the yeast could have been due to several factors: time of collection, demographics of Jasper Ridge, low variety of pollinators, and sugar concentration of the nectar. The results of this study serve as a necessary first step for a recently started research project on ecological interactions between plants, pollinators, and nectar-living yeast. More generally, this research studies the use of the nectar-living yeast community as a natural microcosm for addressing basic questions about the role of dispersal and competitive and facilitative interactions in ecological succession.

Whole Genome Analysis of a Wine Yeast Strain

PubMed Central

Hauser, Nicole C.; Fellenberg, Kurt; Gil, Rosario; Bastuck, Sonja; Hoheisel, Jörg D.

2001-01-01

Saccharomyces cerevisiae strains frequently exhibit rather specific phenotypic features needed for adaptation to a special environment. Wine yeast strains are able to ferment musts, for example, while other industrial or laboratory strains fail to do so. The genetic differences that characterize wine yeast strains are poorly understood, however. As a first search of genetic differences between wine and laboratory strains, we performed DNA-array analyses on the typical wine yeast strain T73 and the standard laboratory background in S288c. Our analysis shows that even under normal conditions, logarithmic growth in YPD medium, the two strains have expression patterns that differ significantly in more than 40 genes. Subsequent studies indicated that these differences correlate with small changes in promoter regions or variations in gene copy number. Blotting copy numbers vs. transcript levels produced patterns, which were specific for the individual strains and could be used for a characterization of unknown samples. PMID:18628902

Effect of Neem Leaf Extract and Neem Oil on Penicillium Growth, Sporulation, Morphology and Ochratoxin A Production

PubMed Central

Mossini, Simone A. G.; Arrotéia, Carla C.; Kemmelmeier, Carlos

2009-01-01

In vitro trials were conducted to evaluate the effect of Azadirachta indica (neem) extracts on mycelial growth, sporulation, morphology and ochratoxin A production by P. verrucosum and P. brevicompactum. The effect of neem oil extract from seeds and leaf was evaluated at 0.125; 0.25 and 0.5% and 6.25 and 12.5 mg/mL, respectively, in Yeast Extract Sucrose (YES) medium. Ochratoxin A production was evaluated by a thin-layer chromatography technique. Oil extracts exhibited significant (p ≤ 0.05) reduction of growth and sporulation of the fungi. No inhibition of ochratoxin A production was observed. Given its accessibility and low cost, neem oil could be implemented as part of a sustainable integrated pest management strategy for plant disease, as it has been shown to be fungitoxic by inhibition of growth and sporulation. PMID:22069528

Effect of neem leaf extract and neem oil on Penicillium growth, sporulation, morphology and ochratoxin A production.

PubMed

Mossini, Simone A G; Arrotéia, Carla C; Kemmelmeier, Carlos

2009-09-01

In vitro trials were conducted to evaluate the effect of Azadirachtaindica (neem) extracts on mycelial growth, sporulation, morphology and ochratoxin A production by P. verrucosum and P. brevicompactum. The effect of neem oil extract from seeds and leaf was evaluated at 0.125; 0.25 and 0.5% and 6.25 and 12.5 mg/mL, respectively, in Yeast Extract Sucrose (YES) medium. Ochratoxin A production was evaluated by a thin-layer chromatography technique. Oil extracts exhibited significant (p ≤ 0.05) reduction of growth and sporulation of the fungi. No inhibition of ochratoxin A production was observed. Given its accessibility and low cost, neem oil could be implemented as part of a sustainable integrated pest management strategy for plant disease, as it has been shown to be fungitoxic by inhibition of growth and sporulation.

Effects of added chelated trace minerals, organic selenium, yeast culture, direct-fed microbials, and Yucca schidigera extract in horses: II. Nutrient excretion and potential environmental impact.

PubMed

Gordon, M E; Edwards, M S; Sweeney, C R; Jerina, M L

2013-08-01

The objective of this study was to test the hypothesis that an equine diet formulated with chelated trace minerals, organic selenium, yeast culture, direct-fed microbials (DFM) and Yucca schidigera extract would decrease excretion of nutrients that have potential for environmental impact. Horses were acclimated to 100% pelleted diets formulated with (ADD) and without (CTRL) the aforementioned additives. Chelated sources of Cu, Zn, Mn, and Co were included in the ADD diet at a 100% replacement rate of sulfate forms used in the CTRL diet. Additionally, the ADD diet included organic selenium yeast, DFM, and Yucca schidigera extract. Ten horses were fed the 2 experimental diets during two 42-d periods in a crossover design. Total fecal and urine collection occurred during the last 14 d of each period. Results indicate no significant differences between Cu, Zn, Mn, and Co concentrations excreted via urine (P > 0.05) due to dietary treatment. There was no difference between fecal Cu and Mn concentrations (P > 0.05) based on diet consumed. Mean fecal Zn and Co concentrations excreted by horses consuming ADD were greater than CTRL (P < 0.003). Differences due to diet were found for selenium fecal (P < 0.0001) and urine (P < 0.0001) excretions, with decreased concentrations found for horses consuming organic selenium yeast (ADD). In contrast, fecal K (%) was greater (P = 0.0421) for horses consuming ADD, whereas concentrations of fecal solids, total N, ammonia N, P, total ammonia, and fecal output did not differ between dietary treatments (P > 0.05). In feces stockpiled to simulate a crude composting method, no differences (P > 0.05) due to diet were detected for particle size, temperature, moisture, OM, total N, P, phosphate, K, moisture, potash, or ammonia N (P > 0.05). Although no difference (P = 0.2737) in feces stockpile temperature due to diet was found, temperature differences over time were documented (P < 0.0001). In conclusion, the addition of certain chelated

High power density yeast catalyzed microbial fuel cells

NASA Astrophysics Data System (ADS)

Ganguli, Rahul

Microbial fuel cells leverage whole cell biocatalysis to convert the energy stored in energy-rich renewable biomolecules such as sugar, directly to electrical energy at high efficiencies. Advantages of the process include ambient temperature operation, operation in natural streams such as wastewater without the need to clean electrodes, minimal balance-of-plant requirements compared to conventional fuel cells, and environmentally friendly operation. These make the technology very attractive as portable power sources and waste-to-energy converters. The principal problem facing the technology is the low power densities compared to other conventional portable power sources such as batteries and traditional fuel cells. In this work we examined the yeast catalyzed microbial fuel cell and developed methods to increase the power density from such fuel cells. A combination of cyclic voltammetry and optical absorption measurements were used to establish significant adsorption of electron mediators by the microbes. Mediator adsorption was demonstrated to be an important limitation in achieving high power densities in yeast-catalyzed microbial fuel cells. Specifically, the power densities are low for the length of time mediator adsorption continues to occur. Once the mediator adsorption stops, the power densities increase. Rotating disk chronoamperometry was used to extract reaction rate information, and a simple kinetic expression was developed for the current observed in the anodic half-cell. Since the rate expression showed that the current was directly related to microbe concentration close to the electrode, methods to increase cell mass attached to the anode was investigated. Electrically biased electrodes were demonstrated to develop biofilm-like layers of the Baker's yeast with a high concentration of cells directly connected to the electrode. The increased cell mass did increase the power density 2 times compared to a non biofilm fuel cell, but the power density

Contribution of yeast and base wine supplementation to sparkling wine composition.

PubMed

Martí-Raga, Maria; Martín, Valentina; Gil, Mariona; Sancho, Marta; Zamora, Fernando; Mas, Albert; Beltran, Gemma

2016-12-01

The differential characteristic of sparkling wine is the formation of foam, which is dependent, among other factors, on yeast autolysis, aging and oenological practices. In this study, we analyzed the effects of yeast strain, nutrient supplementation to the base wine and aging process on the sparkling wine composition and its foamability. We determined that the addition of inorganic nitrogen promoted nitrogen liberation to the extracellular medium, while the addition of inactive dry yeast to the base wine caused an increase in the polysaccharide concentration and foaming properties of the sparkling wine. The use of synthetic and natural base wines allowed us to discriminate that the differences in high-molecular-weight polysaccharides and oligosaccharides could be attributed to the yeast cells and that the higher nitrogen content in the natural wine could be due to external proteolysis. The practices of nitrogen addition and supplementation of inactive dry yeast could modulate the main characteristics of the sparkling wine and be a critical element for the design of this kind of wine. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Growth of non-Saccharomyces yeasts affects nutrient availability for Saccharomyces cerevisiae during wine fermentation.

PubMed

Medina, Karina; Boido, Eduardo; Dellacassa, Eduardo; Carrau, Francisco

2012-07-02

Yeast produces numerous secondary metabolites during fermentation that impact final wine quality. Although it is widely recognized that growth of diverse non-Saccharomyces (NS) yeast can positively affect flavor complexity during Saccharomyces cerevisiae wine fermentation, the inability to control spontaneous or co-fermentation processes by NS yeast has restricted their use in winemaking. We selected two NS yeasts from our Uruguayan native collection to study NS-S. cerevisiae interactions during wine fermentation. The selected strains of Hanseniaspora vineae and Metschnikowia pulcherrima had different yeast assimilable nitrogen consumption profiles and had different effects on S. cerevisiae fermentation and growth kinetics. Studies in which we varied inoculum size and using either simultaneous or sequential inoculation of NS yeast and S. cerevisiae suggested that competition for nutrients had a significant effect on fermentation kinetics. Sluggish fermentations were more pronounced when S. cerevisiae was inoculated 24h after the initial stage of fermentation with a NS strain compared to co-inoculation. Monitoring strain populations using differential WL nutrient agar medium and fermentation kinetics of mixed cultures allowed for a better understanding of strain interactions and nutrient addition effects. Limitation of nutrient availability for S. cerevisiae was shown to result in stuck fermentations as well as to reduce sensory desirability of the resulting wine. Addition of diammonium phosphate (DAP) and a vitamin mix to a defined medium allowed for a comparison of nutrient competition between strains. Addition of DAP and the vitamin mix was most effective in preventing stuck fermentations. Copyright © 2012 Elsevier B.V. All rights reserved.

Analyzing and Understanding Lipids of Yeast: A Challenging Endeavor.

PubMed

Kohlwein, Sepp D

2017-05-01

Lipids are essential biomolecules with diverse biological functions, ranging from building blocks for all biological membranes to energy substrates, signaling molecules, and protein modifiers. Despite advances in lipid analytics by mass spectrometry, the extraction and quantitative analysis of the diverse classes of lipids are still an experimental challenge. Yeast is a model organism that provides several advantages for studying lipid metabolism, because most biosynthetic pathways are well described and a great deal of information is available on the regulatory mechanisms that control lipid homeostasis. In addition, the composition of yeast lipids is much less complex than that of mammalian lipids, making yeast an excellent reference system for studying lipid-associated cell functions. © 2017 Cold Spring Harbor Laboratory Press.

A multiplex culture system for the long‐term growth of fission yeast cells

PubMed Central

Callens, Céline; Coelho, Nelson C.; Miller, Aaron W.; Sananes, Maria Rosa Domingo; Dunham, Maitreya J.; Denoual, Matthieu

2017-01-01

Abstract Maintenance of long‐term cultures of yeast cells is central to a broad range of investigations, from metabolic studies to laboratory evolution assays. However, repeated dilutions of batch cultures lead to variations in medium composition, with implications for cell physiology. In Saccharomyces cerevisiae, powerful miniaturized chemostat setups, or ministat arrays, have been shown to allow for constant dilution of multiple independent cultures. Here we set out to adapt these arrays for continuous culture of a morphologically and physiologically distinct yeast, the fission yeast Schizosaccharomyces pombe, with the goal of maintaining constant population density over time. First, we demonstrated that the original ministats are incompatible with growing fission yeast for more than a few generations, prompting us to modify different aspects of the system design. Next, we identified critical parameters for sustaining unbiased vegetative growth in these conditions. This requires deletion of the gsf2 flocculin‐encoding gene, along with addition of galactose to the medium and lowering of the culture temperature. Importantly, we improved the flexibility of the ministats by developing a piezo‐pump module for the independent regulation of the dilution rate of each culture. This made it possible to easily grow strains that have different generation times in the same assay. Our system therefore allows for maintaining multiple fission yeast cultures in exponential growth, adapting the dilution of each culture over time to keep constant population density for hundreds of generations. These multiplex culture systems open the door to a new range of long‐term experiments using this model organism. © 2017 The Authors. Yeast published by John Wiley & Sons, Ltd. PMID:28426144

Tolerance of budding yeast Saccharomyces cerevisiae to ultra high pressure

NASA Astrophysics Data System (ADS)

Ono, Fumihisa; Shibata, Michiko; Torigoe, Motoki; Matsumoto, Yuta; Yamamoto, Shinsuke; Takizawa, Noboru; Hada, Yoshio; Mori, Yoshihisa; Takarabe, Kenichi

2013-06-01

In our previous studies on the tolerance of small plants and animals to the high hydrostatic pressure of 7.5 GPa, it was shown that all the living samples could be borne at this high pressure, which is more than one order of magnitude higher than the proteinic denaturation pressure. To make this inconsistency clear, we have extended these studies to a smaller sized fungus, budding yeast Saccharomyces cerevisiae. A several pieces of budding yeast (dry yeast) were sealed in a small teflon capsule with a liquid pressure medium fluorinate (PC72, Sumitomo 3M), and exposed to 7.5 GPa by using a cubic anvil press. The pressure was kept constant for various duration of time from 2 to 24 h. After the pressure was released, the specimens were brought out from the teflon capsule, and they were cultivated on a potato dextrose agar (PDA). It was found that the budding yeast exposed to 7.5 GPa for up to 6 h showed multiplication. However, those exposed to 7.5 GPa for 12 and 24 h were found dead. The high pressure tolerance of budding yeast is weaker than that of tardigrades.

Creating a flipbook as a medium of instruction based on the research on activity test of kencur extract

NASA Astrophysics Data System (ADS)

Monika, Icha; Yeni, Laili Fitri; Ariyati, Eka

2016-02-01

This research aimed to reveal the validity of the flipbook as a medium of learning for the sub-material of environmental pollution in the tenth grade based on the results of the activity test of kencur (Kaempferia galanga) extract to control the growth of the Fusarium oxysporum fungus. The research consisted of two stages. First, testing the validity of the medium of flipbook through validation by seven assessors and analyzed based on the total average score of all aspects. Second, testing the activity of the kencur extract against the growth of Fusarium oxysporum by using the experimental method with 10 treatments and 3 repetitions which were analyzed using one-way analysis of variance (ANOVA) test. The making of the flipbook medium was done through the stages of analysis for the potential and problems, data collection, design, validation, and revision. The validation analysis on the flipbook received an average score of 3.7 and was valid to a certain extent, so it could be used in the teaching and learning process especially in the sub-material of environmental pollution in the tenth grade of the senior high school.

Yeast species diversity in apple juice for cider production evidenced by culture-based method.

PubMed

Lorenzini, Marilinda; Simonato, Barbara; Zapparoli, Giacomo

2018-05-07

Identification of yeasts isolated from apple juices of two cider houses (one located in a plain area and one in an alpine area) was carried out by culture-based method. Wallerstein Laboratory Nutrient Agar was used as medium for isolation and preliminary yeasts identification. A total of 20 species of yeasts belonging to ten different genera were identified using both BLAST algorithm for pairwise sequence comparison and phylogenetic approaches. A wide variety of non-Saccharomyces species was found. Interestingly, Candida railenensis, Candida cylindracea, Hanseniaspora meyeri, Hanseniaspora pseudoguilliermondii, and Metschnikowia sinensis were recovered for the first time in the yeast community of an apple environment. Phylogenetic analysis revealed a better resolution in identifying Metschnikowia and Moesziomyces isolates than comparative analysis using the GenBank or YeastIP gene databases. This study provides important data on yeast microbiota of apple juice and evidenced differences between two geographical cider production areas in terms of species composition.

Proteomic and enzymatic response under Cr(VI) overload in yeast isolated from textile-dye industry effluent.

PubMed

Irazusta, Verónica; Bernal, Anahí Romina; Estévez, María Cristina; de Figueroa, Lucía I C

2018-02-01

Cyberlindnera jadinii M9 and Wickerhamomyces anomalus M10 isolated from textile-dye liquid effluents has shown capacity for chromium detoxification via Cr(VI) biological reduction. The aim of the study was to evaluate the effect of hexavalent chromium on synthesis of novel and/or specific proteins involved in chromium tolerance and reduction in response to chromium overload in two indigenous yeasts. A study was carried out following a proteomic approach with W. anomalus M10 and Cy. jadinii M9 strains. For this, proteins extracts belonging to total cell extracts, membranes and mitochondria were analyzed. When Cr(VI) was added to culture medium there was an over-synthesis of 39 proteins involved in different metabolic pathways. In both strains, chromium supplementation changed protein biosynthesis by upregulating proteins involved in stress response, methionine metabolism, energy production, protein degradation and novel oxide-reductase enzymes. Moreover, we observed that Cy. jadinii M9 and W. anomalus M10 displayed ability to activate superoxide dismutase, catalase and chromate reductase activity. Two enzymes from the total cell extracts, type II nitroreductase (Frm2) and flavoprotein wrbA (Ycp4), were identified as possibly responsible for inducing crude chromate-reductase activity in cytoplasm of W. anomalus M10 under chromium overload. In Cy.jadinii M9, mitochondrial Ferredoxine-NADP reductase (Yah1) and membrane FAD flavoprotein (Lpd1) were identified as probably involved in Cr(VI) reduction. To our knowledge, this is the first study proposing chromate reductase activity of these four enzymes in yeast and reporting a relationship between protein synthesis, enzymatic response and chromium biospeciation in Cy. jadinii and W. anomalus. Copyright © 2017 Elsevier Inc. All rights reserved.

Addition of Carbon to the Culture Medium Improves the Detection Efficiency of Aflatoxin Synthetic Fungi

PubMed Central

Suzuki, Tadahiro; Iwahashi, Yumiko

2016-01-01

Aflatoxin (AF) is a harmful secondary metabolite that is synthesized by the Aspergillus species. Although AF detection techniques have been developed, techniques for detection of AF synthetic fungi are still required. Techniques such as plate culture methods are continually being modified for this purpose. However, plate culture methods require refinement because they suffer from several issues. In this study, activated charcoal powder (carbon) was added to a culture medium containing cyclodextrin (CD) to enhance the contrast of fluorescence and improve the detection efficiency for AF synthetic fungi. Two culture media, potato dextrose agar and yeast extract sucrose agar, were investigated using both plate and liquid cultures. The final concentrations of CD and carbon in the media were 3 mg/mL and 0.3 mg/mL, respectively. Addition of carbon improved the visibility of fluorescence by attenuating approximately 30% of light scattering. Several fungi that could not be detected with only CD in the medium were detected with carbon addition. The carbon also facilitated fungal growth in the potato dextrose liquid medium. The results suggest that addition of carbon to media can enhance the observation of AF-derived fluorescence. PMID:27854283

Exo-pectinase production by Bacillus pumilus using different agricultural wastes and optimizing of medium components using response surface methodology.

PubMed

Tepe, Ozlem; Dursun, Arzu Y

2014-01-01

In this research, the production of exo-pectinase by Bacillus pumilus using different agricultural wastes was studied. Agricultural wastes containing pectin such as wheat bran, sugar beet pulp, sunflower plate, orange peel, banana peel, apple pomace and grape pomace were tested as substrates, and activity of exo-pectinase was determined only in the mediums containing sugar beet pulp and wheat bran. Then, effects of parameters such as concentrations of solid substrate (wheat bran and sugar beet pulp) (A), ammonium sulphate (B) and yeast extract (C) on the production of exo-pectinase were investigated by response surface methodology. First, wheat bran was used as solid substrate, and it was determined that exo-pectinase activity increased when relatively low concentrations of ammonium sulphate (0.12-0.21% w/v) and yeast extract (0.12-0.3% w/v) and relatively high wheat bran (~5-6% w/v) were used. Then, exo-pectinase production was optimized by response surface methodology using sugar beet pulp as a solid substrate. In comparison to P values of the coefficients, values of not greater than 0.05 of A and B (2) showed that the effect of these process variables in exo-pectinase production was important and that changes done in these variables will alter the enzyme activity.

[Presumptive identification of Candida spp. and other clinically important yeasts: usefulness of Brilliance Candida Agar].

PubMed

Alfonso, Claudia; López, Mónica; Arechavala, Alicia; Perrone, María Del Carmen; Guelfand, Liliana; Bianchi, Mario

2010-06-30

Fungal infections caused by yeasts have increased during the last decades and invasive forms represent a serious problem for human health. Candida albicans is the species most frequently isolated from clinical samples. However, other emerging yeast pathogens are increasingly responsible for mycotic infections, and some of them are resistant to some antifungal drugs. Consequently, it is necessary to have methods that can provide a rapid presumptive identification at species level. Numerous chromogenic agar media have been shown to be of value as diagnostic tools. We have compared a chromogenic medium, Brilliance Candida Agar, with CHROMagar Candida, the chromogenic medium most used in our country. A multicentre study was conducted in 16 Hospitals belonging to the Mycology Net of Buenos Aires City Government. A total of 240 yeast isolates were included in this research. The new chromogenic agar showed results very similar to those obtained with CHROMagar Candida. Copyright 2009 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.

Selection and identification of oleaginous yeast isolated from soil, animal feed and ruminal fluid for use as feed supplement in dairy cattle.

PubMed

Paserakung, A; Pattarajinda, V; Vichitphan, K; Froetschel, M A

2015-10-01

The purpose of this study was to select oleaginous yeast for microbial lipid production. Sixty-four yeast isolates were obtained from soil (GSY1-12), animal feeds (FDY1-21), and ruminal fluid (RMY1-31) using yeast extract peptone dextrose (YPD) agar. The cultivation of these isolates on nitrogen limited-medium revealed that GSY2 to GSY6, GSY10, FDY2, FDY12 and FDY14 accumulated lipid over 20% of dry biomass. Therefore, they were preliminarily classified as oleaginous yeast. In subsequent experiment, an 8 × 3 factorial in completely randomized design was conducted to examine the effect of eight oleaginous yeast strains and three nitrogen sources (peptone, (NH4 )2 SO4 , urea) on lipid accumulation when using molasses as substrate. The result illustrated that only GSY3 and GSY10 accumulated lipid over 20% of biomass when using peptone or (NH4 )2 SO4 but urea did not. However, GSY10 gave higher biomass and lipid yield than GSY3 (P < 0·05). Identification of GSY10 using 26S rDNA illustrated that GSY10 belongs to Trichosporon asahii. Fatty acid profiles of this strain contained unsaturated fats up to 62·5% of which oleic acid (C18:1 ) was predominant. In conclusion, T. asahii GSY10 was the most promising oleaginous yeast for microbial lipid production from molasses. This study illustrated the ability of T. asahii GSY10 to utilize molasses and (NH4 )2 SO4 for synthesizing and accumulating cellular lipid of which oleic acid (C18:1 ) was predominant. This yeast would be used for microbial lipid production used as feed supplement in dairy cattle. © 2015 The Society for Applied Microbiology.

Rat medium-term multi-organ carcinogenesis bioassay of Agaricus blazei Murrill fruit-body extract.

PubMed

Doi, Yuko; Furukawa, Fumio; Suguro, Mayuko; Ito, Hikaru; Imai, Norio; Nabae, Kyoko; Toda, Yosuke; Inatomi, Satoshi; Kinugasa, Satomi; Kobayashi, Hitoshi

2010-01-01

The modifying potential of Agaricus blazei Murrill fruit-body extract (ABFE) on tumor development was investigated in a medium-term multi-organ carcinogenesis bioassay. Male 6-week-old F344 rats were treated with N-nitrosodiethylamine (DEN), N-methyl-N-nitrosourea (MNU), 1,2-dimethylhydrazine dihydrochloride (DMH), N-butyl-N-(hydroxybutyl)-nitrosamine (BBN), and diisopropanolnitrosamine (DHPN) for initiation (DMBDD treatment). After a 1-week withdrawal period, the animals received distilled water (vehicle control) or ABFE A, gamma-amino butyric acid (GABA) at 0.8 mg/kg, ABFE B (GABA level of 3.0mg/kg) or ABFE C (GABA level of 12.0mg/kg) by gavage for 24 weeks. There were no effects of ABFE on survival rate, general condition, body weight, food and water consumption, and organ weights. The multiplicity of large intestinal nodules, smaller than 2mm was significantly increased in the ABFE C group with DMBDD treatment. However, there were no significantly inter-group differences in incidences of hyperplastic or neoplastic lesions in colon or other organs, or in immunohistochemically identified preneoplastic lesions in the liver. In conclusion, A. blazei Murrill fruit-body extract, even at a GABA level up to 12 mg/kg, did not exert modifying potential in the present medium-term multi-organ carcinogenesis bioassay in male F344 rats (DMBDD method). Copyright 2009 Elsevier Ltd. All rights reserved.

Bioconversion of R-(+)-limonene to perillic acid by the yeast Yarrowia lipolytica

PubMed Central

Ferrara, Maria Antonieta; Almeida, Débora S.; Siani, Antonio C.; Lucchetti, Leonardo; Lacerda, Paulo S.B.; Freitas, André; Tappin, Marcelo R.R.; Bon, Elba P.S.

2013-01-01

Perillyl derivatives are increasingly important due to their flavouring and antimicrobial properties as well as their potential as anticancer agents. These terpenoid species, which are present in limited amounts in plants, may be obtained via bioconversion of selected monoterpene hydrocarbons. In this study, seventeen yeast strains were screened for their ability to oxidize the exocyclic methyl group in the p-menthene moiety of limonene into perillic acid. Of the yeast tested, the highest efficiency was observed for Yarrowia lipolytica ATCC 18942. The conversion of R (+)-limonene by Y. lipolytica was evaluated by varying the pH (3 to 8) and the temperature (25 to 30 °C) in a reaction medium containing 0.5% v/v limonene and 10 g/L of stationary phase cells (dry weight). The best results, corresponding to 564 mg/L of perillic acid, were obtained in buffered medium at pH 7.1 that was incubated at 25 °C for 48 h. The stepwise addition of limonene increased the perillic acid concentration by over 50%, reaching 855 mg/L, whereas the addition of glucose or surfactant to the reaction medium did not improve the bioconversion process. The use of Y. lipolytica showed promise for ease of further downstream processing, as perillic acid was the sole oxidised product of the bioconversion reaction. Moreover, bioprocesses using safe and easy to cultivate yeast cells have been favoured in industry. PMID:24688495

Chitosan inhibits enterotoxigenic Clostridium perfringens type A in growth medium and chicken meat.

PubMed

Alnoman, Maryam; Udompijitkul, Pathima; Sarker, Mahfuzur R

2017-06-01

Clostridium perfringens is a spore-forming bacterium and a major cause of bacterial food-borne illness. In this study, we evaluated the inhibitory effects of chitosan against spore germination, spore outgrowth and vegetative growth of C. perfringens food poisoning (FP) isolates. Chitosan of differing molecular weights inhibited germination of spores of all tested FP isolates in a KCl germinant solution containing 0.1 mg/ml chitosan at pH 4.5. However, higher level (0.25 mg/ml) of chitosan was required to effectively arrest outgrowth of the germinated C. perfringens spores in Tripticase-yeast extract-glucose (TGY) medium. Furthermore, chitosan (1.0 mg/ml) was bacteriostatic against vegetative cells of C. perfringens in TGY medium. Although chitosan showed strong inhibitory activities against C. perfringens in laboratory medium, higher levels (2.0 mg/g) were required to achieve similar inhibition of spores inoculated into chicken meat. In summary, the inhibitory effects of chitosan against C. perfringens FP isolates was concentration dependent, and no major difference was observed when using different molecule weight chitosan as an inhibitor. Our results contribute to a better understanding on the potential application of chitosan in cooked meat products to control C. perfringens-associated disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

Appearance of colonies of Prototheca on CHROMagar Candida medium.

PubMed

Casal, M; Linares, M J; Solís, F; Rodríguez, F C

1997-01-01

The microorganisms capable of producing opportunist infections include the yeast-like organisms of the genus Candida, and the unicellular algae of the genus Prototheca, which share common features and can, therefore, lead to confusion. Their colonies are almost identical and they grow in the same culture media used routinely in mycology. CHROMagar Candida is a new chromogenic differential isolation medium that facilitates the presumptive differentiation of some of the most clinically important yeast-like organisms. To our knowledge, the use of CHROMagar Candida with Prototheca spp. has not been reported in the literature. This report describes the growth of 151 strains of Prototheca on CHROMagar Candida compared to the growth of a total of 326 well-characterized yeast organisms of the genera Candida, Cryptococcus, Trichosporon, Geotrichum, and Saccharomyces. It is clinically relevant to note that algae of the genus Prototheca (P. wickerhamii, P. zopfii, and P. stagnora) and of the genus Candida parapsilosis produced similar cream-colored colonies on CHROMagar Candida medium. Based on their growth on CHROMagar, a new species of Candida is described, C. zeylanoides, which has blue-green colonies. The colonies of two species of Trichosporon are also differentiated: the blue-green colonies of T. beigelii and the pink colonies of T. capitatum.

Carbon source utilization and inhibitor tolerance of 45 oleaginous yeast species

PubMed Central

Sitepu, Irnayuli; Selby, Tylan; Lin, Ting; Zhu, Shirley; Boundy-Mills, Kyria

2014-01-01

Conversion of lignocellulosic hydrolysates to lipids using oleaginous (high lipid) yeasts requires alignment of the hydrolysate composition with the characteristics of the yeast strain, including ability to utilize certain nutrients, ability to grow independently of costly nutrients such as vitamins, and ability to tolerate inhibitors. Some combination of these characteristics may be present in wild strains. In this study, 48 oleaginous yeast strains belonging to 45 species were tested for ability to utilize carbon sources associated with lignocellulosic hydrolysates, tolerate inhibitors, and grow in medium without supplemented vitamins. Some well-studied oleaginous yeast species, as well as some that have not been frequently utilized in research or industrial production, emerged as promising candidates for industrial use due to ability to utilize many carbon sources, including Cryptococcus aureus, Cryptococcus laurentii, Hanaella aff. zeae, Tremella encephala, and Trichosporon coremiiforme. Other species excelled in inhibitor tolerance, including Candida aff. tropicalis, Cyberlindnera jadinii, Metschnikowia pulcherrima Schwanniomyces occidentalis and Wickerhamomyces ciferii. No yeast tested could utilize all carbon sources and tolerate all inhibitors tested. These results indicate that yeast strains should be selected based on characteristics compatible with the composition of the targeted hydrolysate. Other factors to consider include the production of valuable co-products such as carotenoids, availability of genetic tools, biosafety level, and flocculation of the yeast strain. The data generated in this study will aid in aligning yeasts with compatible hydrolysates for conversion of carbohydrates to lipids to be used for biofuels and other oleochemicals. PMID:24818698

Cow dung extract: a medium for the growth of pseudomonads enhancing their efficiency as biofertilizer and biocontrol agent in rice.

PubMed

Srivastava, Rashmi; Aragno, Michel; Sharma, A K

2010-09-01

Some pseudomands are being utilized as biofertilizers and biopesticides because of their role in plant growth promotion and plant protection against root parasites, respectively. Two strains of Pseudomonas, P. jessenii LHRE62 and P. synxantha HHRE81, recovered from wheat rhizosphere, have shown their potential in field bioinoculation tests under rice-wheat and pulse-wheat rotation systems. Normally, pseudomonads are cultivated on synthetic media-like King's B and used for inoculation on seeds/soil drench with talcum or charcoal as carrier material. Cow dung is being used for different purposes from the ancient time and has a significant role in crop growth because of the content in humic compounds and fertilizing bioelements available in it. Here, cow dung extract was tested as a growth medium for strains LHRE62 and HHRE81, in comparison with growth in King's B medium. The log phase was delayed by 2 h as compared to growth in King's B medium. The bacterial growth yield, lower in plain cow dung extract as compared to King's B medium, was improved upon addition of different carbon substrates. Growth of rice var. Pant Dhan 4 in pot cultures was increased using liquid formulation of cow dung extract and bacteria as foliar spray, compared to their respective controls. Biocontrol efficacy of the bioagents was assessed by challenging rice crop with Rhizoctonia solani, a sheath blight pathogen. The growth promotion and biocontrol efficiencies were more pronounced in the case of mixed inocula of strains LHRE62 and HHRE81.

Expression of the Major Surface Antigen of Plasmodium knowlesi Sporozoites in Yeast

NASA Astrophysics Data System (ADS)

Sharma, Shobhona; Godson, G. Nigel

1985-05-01

The circumsporozoite protein, a surface antigen of the sporozoite stage of the monkey malarial parasite Plasmodium knowlesi, was expressed in the yeast Saccharomyces cerevisiae by using an expression vector containing the 5' regulatory region of the yeast alcohol dehydrogenase I gene. It was necessary to eliminate the entire 5' upstream region of the parasite DNA to obtain the expression of this protein. Only the circumsporozoite precursor protein was produced by the yeast transformants, as detected by immunoblotting. About 55 and 20 percent of the circumsporozoite protein produced in yeast was associated with the 25,000g and 150,000g particulate fractions, respectively. The protein could be solubilized in Triton X-100 and was stable in solubilized extracts.

Biosynthesis of Drug Glucuronide Metabolites in the Budding Yeast Saccharomyces cerevisiae.

PubMed

Ikushiro, Shinichi; Nishikawa, Miyu; Masuyama, Yuuka; Shouji, Tadashi; Fujii, Miharu; Hamada, Masahiro; Nakajima, Noriyuki; Finel, Moshe; Yasuda, Kaori; Kamakura, Masaki; Sakaki, Toshiyuki

2016-07-05

Glucuronidation is one of the most common pathways in mammals for detoxification and elimination of hydrophobic xenobiotic compounds, including many drugs. Metabolites, however, can form active or toxic compounds, such as acyl glucuronides, and their safety assessment is often needed. The absence of efficient means for in vitro synthesis of correct glucuronide metabolites frequently limits such toxicological analyses. To overcome this hurdle we have developed a new approach, the essence of which is a coexpression system containing a human, or another mammalian UDP-glucuronosyltransferases (UGTs), as well as UDP-glucose-6-dehydrogenase (UGDH), within the budding yeast, Saccharomyces cerevisiae. The system was first tested using resting yeast cells coexpressing UGDH and human UGT1A6, 7-hydroxycoumarin as the substrate, in a reaction medium containing 8% glucose, serving as a source of UDP-glucuronic acid. Glucuronides were readily formed and recovered from the medium. Subsequently, by selecting suitable mammalian UGT enzyme for the coexpression system we could obtain the desired glucuronides of various compounds, including molecules with multiple conjugation sites and acyl glucuronides of several carboxylic acid containing drugs, namely, mefenamic acid, flufenamic acid, and zomepirac. In conclusion, a new and flexible yeast system with mammalian UGTs has been developed that exhibits a capacity for efficient production of various glucuronides, including acyl glucuronides.

Preparation of corncob grits as a carrier for immobilizing yeast cells for ethanol production.

PubMed

Lee, Sang-Eun; Lee, Choon Geun; Kang, Do Hyung; Lee, Hyeon-Yong; Jung, Kyung-Hwan

2012-12-01

In this study, DEAE-corncobs [delignified corncob grits derivatized with 2-(diethylamino)ethyl chloride hydrochloride (DEAE·HCl)] were prepared as a carrier to immobilize yeast (Saccharomyces cerevisiae) for ethanol production. The immobilized yeast cell reactor produced ethanol under optimized DEAE·HCl derivatization and adsorption conditions between yeast cells and the DEAE-corncobs. When delignified corncob grit (3.0 g) was derivatized with 0.5M DEAE·HCl, the yeast cell suspension (OD600 = 3.0) was adsorbed at >90% of the initial cell OD600. This amount of adsorbed yeast cells was estimated to be 5.36 mg-dry cells/g-DEAE corncobs. The Qmax (the maximum cell adsorption by the carrier) of the DEAE-corncobs was estimated to be 25.1 (mg/g), based on a Languir model biosorption isotherm experiment. When we conducted a batch culture with medium recycling using the immobilized yeast cells, the yeast cells on DEAE-corncobs produced ethanol gradually, according to glucose consumption, without cells detaching from the DEAE-corncobs. We observed under electron microscopy that the yeast cells grew on the surface and in the holes of the DEAEcorncobs. In a future study, DEAE-corncobs and the immobilized yeast cell reactor system will contribute to bioethanol production from biomass hydrolysates.

Indole-3-Acetic Acid-Producing Yeasts in the Phyllosphere of the Carnivorous Plant Drosera indica L

PubMed Central

Shin, Li-Ying; Wei, Jyuan-Yu; Fu, Shih-Feng; Chou, Jui-Yu

2014-01-01

Yeasts are widely distributed in nature and exist in association with other microorganisms as normal inhabitants of soil, vegetation, and aqueous environments. In this study, 12 yeast strains were enriched and isolated from leaf samples of the carnivorous plant Drosera indica L., which is currently threatened because of restricted habitats and use in herbal industries. According to similarities in large subunit and small subunit ribosomal RNA gene sequences, we identified 2 yeast species in 2 genera of the phylum Ascomycota, and 5 yeast species in 5 genera of the phylum Basidiomycota. All of the isolated yeasts produced indole-3-acetic acid (IAA) when cultivated in YPD broth supplemented with 0.1% L-tryptophan. Growth conditions, such as the pH and temperature of the medium, influenced yeast IAA production. Our results also suggested the existence of a tryptophan-independent IAA biosynthetic pathway. We evaluated the effects of various concentrations of exogenous IAA on yeast growth and observed that IAA produced by wild yeasts modifies auxin-inducible gene expression in Arabidopsis. Our data suggest that yeasts can promote plant growth and support ongoing prospecting of yeast strains for inclusion into biofertilizer for sustainable agriculture. PMID:25464336

Selection and Characterization of Potential Baker's Yeast from Indigenous Resources of Nepal

PubMed Central

Timilsina, Parash Mani; Yadav, Archana; Joshi, Yogesh; Bhujel, Sahansila; Adhikari, Rojina; Neupane, Katyayanee

2017-01-01

The study aims to isolate the yeast strains that could be used effectively as baker's yeast and compare them with the commercial baker's yeast available in the market of Nepal. A total of 10 samples including locally available sources like fruits, Murcha, and a local tree “Dar” were collected from different localities of Bhaktapur, Kavre, and Syangja districts of Nepal, respectively. Following enrichment and fermentation of the samples, 26 yeast strains were isolated using selective medium Wallerstein Laboratory Nutrient Agar. From the differential tests which included morphological and microscopic observation and physiological and biochemical characterization such as nitrate reduction and lactose utilization tests, 8 strains were selected as possible Saccharomyces strain. The selected strains were further assessed for their efficient leavening ability by tests such as ethanol tolerance, osmotolerance, invertase test, and stress exclusion test. The three most potent strains ENG, MUR3B, and SUG1 isolated from grape, Murcha, and sugarcane, respectively, were used in the fermentation and baking of dough. These strains also carried a possibility of being used as industrial baker's yeast. PMID:29387490

Selection and Characterization of Potential Baker's Yeast from Indigenous Resources of Nepal.

PubMed

Karki, Tika B; Timilsina, Parash Mani; Yadav, Archana; Pandey, Gyanu Raj; Joshi, Yogesh; Bhujel, Sahansila; Adhikari, Rojina; Neupane, Katyayanee

2017-01-01

The study aims to isolate the yeast strains that could be used effectively as baker's yeast and compare them with the commercial baker's yeast available in the market of Nepal. A total of 10 samples including locally available sources like fruits, Murcha, and a local tree "Dar" were collected from different localities of Bhaktapur, Kavre, and Syangja districts of Nepal, respectively. Following enrichment and fermentation of the samples, 26 yeast strains were isolated using selective medium Wallerstein Laboratory Nutrient Agar. From the differential tests which included morphological and microscopic observation and physiological and biochemical characterization such as nitrate reduction and lactose utilization tests, 8 strains were selected as possible Saccharomyces strain. The selected strains were further assessed for their efficient leavening ability by tests such as ethanol tolerance, osmotolerance, invertase test, and stress exclusion test. The three most potent strains ENG, MUR3B, and SUG1 isolated from grape, Murcha, and sugarcane, respectively, were used in the fermentation and baking of dough. These strains also carried a possibility of being used as industrial baker's yeast.

Cloning of a yeast alpha-amylase promoter and its regulated heterologous expression

DOEpatents

Gao, Johnway [Richland, WA; Skeen, Rodney S [Pendleton, OR; Hooker, Brian S [Kennewick, WA; Anderson, Daniel B [Pasco, WA

2003-04-01

The present invention provides the promoter clone discovery of an alpha-amylase gene of a starch utilizing yeast strain Schwanniomyces castellii. The isolated alpha-amylase promoter is an inducible promoter, which can regulate strong gene expression in starch culture medium.

Effects of α-Glycerophosphate and of Palmityl-Coenzyme A on Lipid Synthesis in Yeast Extracts

PubMed Central

White, David; Klein, Harold P.

1966-01-01

White, David (Ames Research Center, Moffett Field, Calif.), and Harold P. Klein. Effects of α-glycerophosphate and of palmityl-coenzyme A on lipid synthesis in yeast extracts. J. Bacteriol. 91:1218–1223. 1966.—The incorporation of acetate into fatty acids, but not into nonsaponifiable lipids, was stimulated by α-glycerophosphate in a supernatant fraction of Saccharomyces cerevisiae, obtained after centrifugation at 86,000 × g for 60 min. There was a pronounced effect at concentrations below 2 mm, but at concentrations above 5 mm α-glycerophosphate was relatively less stimulatory. α-Glycerophosphate markedly increased the percentage of esterified fatty acids among the products, and the formation of both saturated and unsaturated fatty acids was stimulated. Palmityl-coenzyme A inhibited fatty acid synthesis, affecting the formation of unsaturated acids more severely than saturated acids. In the presence of sufficient α-glycerophosphate to alleviate these inhibitions, palmityl-coenzyme A still reduced the formation of certain unsaturated fatty acids. PMID:5929752

Divergence of iron metabolism in wild Malaysian yeast.

PubMed

Lee, Hana N; Mostovoy, Yulia; Hsu, Tiffany Y; Chang, Amanda H; Brem, Rachel B

2013-12-09

Comparative genomic studies have reported widespread variation in levels of gene expression within and between species. Using these data to infer organism-level trait divergence has proven to be a key challenge in the field. We have used a wild Malaysian population of S. cerevisiae as a test bed in the search to predict and validate trait differences based on observations of regulatory variation. Malaysian yeast, when cultured in standard medium, activated regulatory programs that protect cells from the toxic effects of high iron. Malaysian yeast also showed a hyperactive regulatory response during culture in the presence of excess iron and had a unique growth defect in conditions of high iron. Molecular validation experiments pinpointed the iron metabolism factors AFT1, CCC1, and YAP5 as contributors to these molecular and cellular phenotypes; in genome-scale sequence analyses, a suite of iron toxicity response genes showed evidence for rapid protein evolution in Malaysian yeast. Our findings support a model in which iron metabolism has diverged in Malaysian yeast as a consequence of a change in selective pressure, with Malaysian alleles shifting the dynamic range of iron response to low-iron concentrations and weakening resistance to extreme iron toxicity. By dissecting the iron scarcity specialist behavior of Malaysian yeast, our work highlights the power of expression divergence as a signpost for biologically and evolutionarily relevant variation at the organismal level. Interpreting the phenotypic relevance of gene expression variation is one of the primary challenges of modern genomics.

Rappaport-Vassiliadis medium for recovery of Salmonella spp. from low microbial load foods: collaborative study.

PubMed

Hammack, T S; Amaguaña, R M; Andrews, W H; Lerner, I

2001-01-01

Twenty-three laboratories participated in a collaborative study to compare the relative effectiveness of Rappaport-Vassiliadis (RV) medium incubated at 42 degrees C, selenite cystine (SC) broth (35 degrees C), and tetrathionate (TT) broth (35 and 43 degrees C) for recovery of Salmonella from the following foods with a low microbial load: dried egg yolk, dry active yeast, ground black pepper, guar gum, and instant nonfat dry milk. For dry active yeast, lauryl tryptose (LT) broth, incubated at 35 degrees C, was used instead of SC broth. All of the foods were artificially inoculated with single Salmonella serovars, that had been lyophilized before inoculation, at high and low target levels of 0.4 and 0.04 colony forming units/g food, respectively. For analysis of 870 test portions, representing all of the foods except yeast, 249 Salmonella-positive test portions were detected by RV medium, 265 by TT broth (43 degrees C), 268 by TT broth (35 degrees C), and 269 by SC broth (35 degrees C). For analysis of 225 test portions of yeast, 79 Salmonella-positive test portions were detected by RV medium, 79 by TT broth (43 degrees C), 84 by TT broth (35 degrees C), and 68 by LT broth (35 degrees C). RV medium was comparable to, or even more effective than, the other selective enrichments for recovery of Salmonella from all of the foods except guar gum. It is recommended that RV (42 degrees C) and TT (35 degrees C) be used with foods that have a low microbial load, except for guar gum for which SC (35 degrees C) and TT (35 degrees C) are recommended.

Mixed-species biofilm formation by lactic acid bacteria and rice wine yeasts.

PubMed

Kawarai, Taketo; Furukawa, Soichi; Ogihara, Hirokazu; Yamasaki, Makari

2007-07-01

We found that species combinations such as Lactobacillus casei subsp. rhamnosus IFO3831 and Saccharomyces cerevisiae Kyokai-10 can form a mixed-species biofilm in coculture. Moreover, the Kyokai-10 yeast strain can form a biofilm in monoculture in the presence of conditioned medium (CM) from L. casei IFO3831. The active substance(s) in bacterial CM is heat sensitive and has a molecular mass of between 3 and 5 kDa. In biofilms from cocultures or CM monocultures, yeast cells had a distinct morphology, with many hill-like protrusions on the cell surface.

In vitro studies on the translocation of acid phosphatase into the endoplasmic reticulum of the yeast Saccharomyces cerevisiae.

PubMed

Krebs, H O; Hoffschulte, H K; Müller, M

1989-05-01

We demonstrate here the in vitro translocation of yeast acid phosphatase into rough endoplasmic reticulum. The precursor of the repressible acid phosphatase from Saccharomyces cerevisiae encoded by the PHO5 gene, was synthesized in a yeast lysate programmed with in vitro transcribed PHO5 mRNA. In the presence of yeast rough microsomes up to 16% of the acid phosphatase synthesized was found to be translocated into the microsomes, as judged by proteinase resistance, and fully core-glycosylated. The translocation efficiency however, decreased to 3% if yeast rough microsomes were added after synthesis of acid phosphatase had been terminated. When a wheat-germ extract was used for in vitro synthesis, the precursor of acid phosphatase was translocated into canine pancreatic rough microsomes and thereby core-glycosylated in a signal-recognition-particle-dependent manner. Replacing canine with yeast rough microsomes in the wheat-germ translation system, however, resulted in a significant decrease in the ability to translocate and glycosylate the precursor. Translocation and glycosylation were partially restored by a high-salt extract prepared from yeast ribosomes. The results presented here suggest that yeast-specific factors are needed to translocate and glycosylate acid phosphatase efficiently in vitro.

L-carnosine enhanced reproductive potential of the Saccharomyces cerevisiae yeast growing on medium containing glucose as a source of carbon.

PubMed

Kwolek-Mirek, Magdalena; Molon, Mateusz; Kaszycki, Pawel; Zadrag-Tecza, Renata

2016-08-01

Carnosine is an endogenous dipeptide composed of β-alanine and L-histidine, which occurs in vertebrates, including humans. It has a number of favorable properties including buffering, chelating, antioxidant, anti-glycation and anti-aging activities. In our study we used the Saccharomyces cerevisiae yeast as a model organism to examine the impact of L-carnosine on the cell lifespan. We demonstrated that L-carnosine slowed down the growth and decreased the metabolic activity of cells as well as prolonged their generation time. On the other hand, it allowed for enhancement of the yeast reproductive potential and extended its reproductive lifespan. These changes may be a result of the reduced mitochondrial membrane potential and decreased ATP content in the yeast cells. However, due to reduction of the post-reproductive lifespan, L-carnosine did not have an influence on the total lifespan of yeast. In conclusion, L-carnosine does not extend the total lifespan of S. cerevisiae but rather it increases the yeast's reproductive capacity by increasing the number of daughter cells produced.

l-Pyroglutamate Spontaneously Formed from l-Glutamate Inhibits Growth of the Hyperthermophilic Archaeon Sulfolobus solfataricus

PubMed Central

Park, Chan B.; Lee, Sun Bok; Ryu, Dewey D. Y.

2001-01-01

Identification of physiological and environmental factors that limit efficient growth of hyperthermophiles is important for practical application of these organisms to the production of useful enzymes or metabolites. During fed-batch cultivation of Sulfolobus solfataricus in medium containing l-glutamate, we observed formation of l-pyroglutamic acid (PGA). PGA formed spontaneously from l-glutamate under culture conditions (78°C and pH 3.0), and the PGA formation rate was much higher at an acidic or alkaline pH than at neutral pH. It was also found that PGA is a potent inhibitor of S. solfataricus growth. The cell growth rate was reduced by one-half by the presence of 5.1 mM PGA, and no growth was observed in the presence of 15.5 mM PGA. On the other hand, the inhibitory effect of PGA on cell growth was alleviated by addition of l-glutamate or l-aspartate to the medium. PGA was also produced from the l-glutamate in yeast extract; the PGA content increased to 8.5% (wt/wt) after 80 h of incubation of a yeast extract solution at 78°C and pH 3.0. In medium supplemented with yeast extract, cell growth was optimal in the presence of 3.0 g of yeast extract per liter, and higher yeast extract concentrations resulted in reduced cell yields. The extents of cell growth inhibition at yeast extract concentrations above the optimal concentration were correlated with the PGA concentration in the culture broth. Although other structural analogues of l-glutamate, such as l-methionine sulfoxide, glutaric acid, succinic acid, and l-glutamic acid γ-methyl ester, also inhibited the growth of S. solfataricus, the greatest cell growth inhibition was observed with PGA. We also observed that unlike other glutamate analogues, N-acetyl-l-glutamate enhanced the growth of S. solfataricus. This compound was stable under cell culture conditions, and replacement of l-glutamate with N-acetyl-l-glutamate in the medium resulted in increased cell density. PMID:11472943

Phenotypic and metabolic traits of commercial Saccharomyces cerevisiae yeasts

PubMed Central

2014-01-01

Currently, pursuing yeast strains that display both a high potential fitness for alcoholic fermentation and a favorable impact on quality is a major goal in the alcoholic beverage industry. This considerable industrial interest has led to many studies characterizing the phenotypic and metabolic traits of commercial yeast populations. In this study, 20 Saccharomyces cerevisiae strains from different geographical origins exhibited high phenotypic diversity when their response to nine biotechnologically relevant conditions was examined. Next, the fermentation fitness and metabolic traits of eight selected strains with a unique phenotypic profile were evaluated in a high-sugar synthetic medium under two nitrogen regimes. Although the strains exhibited significant differences in nitrogen requirements and utilization rates, a direct relationship between nitrogen consumption, specific growth rate, cell biomass, cell viability, acetic acid and glycerol formation was only observed under high-nitrogen conditions. In contrast, the strains produced more succinic acid under the low-nitrogen regime, and a direct relationship with the final cell biomass was established. Glucose and fructose utilization patterns depended on both yeast strain and nitrogen availability. For low-nitrogen fermentation, three strains did not fully degrade the fructose. This study validates phenotypic and metabolic diversity among commercial wine yeasts and contributes new findings on the relationship between nitrogen availability, yeast cell growth and sugar utilization. We suggest that measuring nitrogen during the stationary growth phase is important because yeast cells fermentative activity is not exclusively related to population size, as previously assumed, but it is also related to the quantity of nitrogen consumed during this growth phase. PMID:24949272

Phenotypic and metabolic traits of commercial Saccharomyces cerevisiae yeasts.

PubMed

Barbosa, Catarina; Lage, Patrícia; Vilela, Alice; Mendes-Faia, Arlete; Mendes-Ferreira, Ana

2014-01-01

Currently, pursuing yeast strains that display both a high potential fitness for alcoholic fermentation and a favorable impact on quality is a major goal in the alcoholic beverage industry. This considerable industrial interest has led to many studies characterizing the phenotypic and metabolic traits of commercial yeast populations. In this study, 20 Saccharomyces cerevisiae strains from different geographical origins exhibited high phenotypic diversity when their response to nine biotechnologically relevant conditions was examined. Next, the fermentation fitness and metabolic traits of eight selected strains with a unique phenotypic profile were evaluated in a high-sugar synthetic medium under two nitrogen regimes. Although the strains exhibited significant differences in nitrogen requirements and utilization rates, a direct relationship between nitrogen consumption, specific growth rate, cell biomass, cell viability, acetic acid and glycerol formation was only observed under high-nitrogen conditions. In contrast, the strains produced more succinic acid under the low-nitrogen regime, and a direct relationship with the final cell biomass was established. Glucose and fructose utilization patterns depended on both yeast strain and nitrogen availability. For low-nitrogen fermentation, three strains did not fully degrade the fructose. This study validates phenotypic and metabolic diversity among commercial wine yeasts and contributes new findings on the relationship between nitrogen availability, yeast cell growth and sugar utilization. We suggest that measuring nitrogen during the stationary growth phase is important because yeast cells fermentative activity is not exclusively related to population size, as previously assumed, but it is also related to the quantity of nitrogen consumed during this growth phase.

Application of microalgae hydrolysate as a fermentation medium for microbial production of 2-pyrone 4,6-dicarboxylic acid.

PubMed

Htet, April N; Noguchi, Mana; Ninomiya, Kazuaki; Tsuge, Yota; Kuroda, Kosuke; Kajita, Shinya; Masai, Eiji; Katayama, Yoshihiro; Shikinaka, Kazuhiro; Otsuka, Yuichiro; Nakamura, Masaya; Honda, Ryo; Takahashi, Kenji

2018-06-01

Actual biomass of microalgae was tested as a fermentation substrate for microbial production of 2-pyrone 4,6-dicarboxylic acid (PDC). Acid-hydrolyzed green microalgae Chlorella emersonii (algae hydrolysate) was diluted to adjust the glucose concentration to 2 g/L and supplemented with the nutrients of Luria-Bertani (LB) medium (tryptone 10 g/L and yeast extract 5 g/L). When the algae hydrolysate was used as a fermentation source for recombinant Escherichia coli producing PDC, 0.43 g/L PDC was produced with a yield of 20.1% (mol PDC/mol glucose), whereas 0.19 g/L PDC was produced with a yield of 8.6% when LB medium supplemented with glucose was used. To evaluate the potential of algae hydrolysate alone as a fermentation medium for E. coli growth and PDC production, the nutrients of LB medium were reduced from the algae hydrolysate medium. Interestingly, 0.17 g/L PDC was produced even without additional nutrient, which was comparable to the case using pure glucose medium with nutrients of LB medium. When using a high concentration of hydrolysate without additional nutrients, 1.22 g/L PDC was produced after a 24-h cultivation with the yield of 16.1%. Overall, C. emersonii has high potential as cost-effective fermentation substrate for the microbial production of PDC. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

FORMATION OF AUXIN IN YEAST CULTURES.

PubMed

Robinson, T W; Stier, T J

1941-07-20

We have found far more auxin in the culture media of bakers' yeast than was obtained by Kögl and Kostermans from the cells themselves. The production of auxin by yeast cells resembles the formation observed in other organisms such as Rhizopus and Rhizobium which also form auxins in their culture media. The auxin yield was found to increase with the concentration of sucrose and to decrease with the concentration of peptone. An inverse relation with the rate of cell multiplication was observed. Enlarged and elongated cells appeared only in those media which contained considerable amounts of auxin. The total auxin yield in the various cultures was found to be directly proportional, below pH 5, to the hydrogen ion concentration. Thus, it was proposed that certain growth conditions favor the breakage of the link between auxin and its protein carrier (Skoog and Thimann) 1940) and consequently accelerate the rate of excretion of auxin into the growth medium.

Antimicrobial activity of grapefruit seed and pulp ethanolic extract.

PubMed

Cvetnić, Zdenka; Vladimir-Knezević, Sanda

2004-09-01

Antibacterial and antifungal activity of ethanolic extract of grapefruit (Citrus paradisi Macf., Rutaceae) seed and pulp was examined against 20 bacterial and 10 yeast strains. The level of antimicrobial effects was established using an in vitro agar assay and standard broth dilution susceptibility test. The contents of 3.92% of total polyphenols and 0.11% of flavonoids were determined spectrometrically in crude ethanolic extract. The presence of flavanones naringin and hesperidin in the extract was confirmed by TLC analysis. Ethanolic extract exibited the strongest antimicrobial effect against Salmonella enteritidis (MIC 2.06%, m/V). Other tested bacteria and yeasts were sensitive to extract concentrations ranging from 4.13% to 16.50% (m/V).

Proteomic study of the yeast Rhodotorula mucilaginosa RCL-11 under copper stress.

PubMed

Irazusta, Verónica; Estévez, Cristina; Amoroso, María Julia; de Figueroa, Lucía I C

2012-06-01

In order to understand the mechanism involved in Rhodotorula mucilaginosa RCL-11 resistance to copper a proteomic study was conducted. Atomic absorption spectroscopy showed that the copper concentration in the medium decreased from 0.5 to 0.19 mM 48 h after inoculation of the yeast. Analysis of one-dimensional gel electrophoresis of crude cell extracts revealed expression of differential bands between cells with and without copper. In order to study this difference, two-dimensional electrophoresis of R. mucilaginosa RCL-11 exposed to Cu for 16, 24, and 48 h was carried out. Identification of differentially expressed proteins was performed by MALDI-TOF/TOF. Ten of the 16 spots identified belonged to heat shock proteins. Superoxide dismutase, methionine synthase and beta-glucosidase were also found over-expressed at high copper concentrations. The results obtained in the present work show that when R. mucilaginosa RCL-11 is exposed to 0.5 mM copper, differential proteins, involved in cell resistance mechanisms, are expressed.

Induction of multiple pleiotropic drug resistance genes in yeast engineered to produce an increased level of anti-malarial drug precursor, artemisinic acid.

PubMed

Ro, Dae-Kyun; Ouellet, Mario; Paradise, Eric M; Burd, Helcio; Eng, Diana; Paddon, Chris J; Newman, Jack D; Keasling, Jay D

2008-11-04

Due to the global occurrence of multi-drug-resistant malarial parasites (Plasmodium falciparum), the anti-malarial drug most effective against malaria is artemisinin, a natural product (sesquiterpene lactone endoperoxide) extracted from sweet wormwood (Artemisia annua). However, artemisinin is in short supply and unaffordable to most malaria patients. Artemisinin can be semi-synthesized from its precursor artemisinic acid, which can be synthesized from simple sugars using microorganisms genetically engineered with genes from A. annua. In order to develop an industrially competent yeast strain, detailed analyses of microbial physiology and development of gene expression strategies are required. Three plant genes coding for amorphadiene synthase, amorphadiene oxidase (AMO or CYP71AV1), and cytochrome P450 reductase, which in concert divert carbon flux from farnesyl diphosphate to artemisinic acid, were expressed from a single plasmid. The artemisinic acid production in the engineered yeast reached 250 microg mL(-1) in shake-flask cultures and 1 g L(-1) in bio-reactors with the use of Leu2d selection marker and appropriate medium formulation. When plasmid stability was measured, the yeast strain synthesizing amorphadiene alone maintained the plasmid in 84% of the cells, whereas the yeast strain synthesizing artemisinic acid showed poor plasmid stability. Inactivation of AMO by a point-mutation restored the high plasmid stability, indicating that the low plasmid stability is not caused by production of the AMO protein but by artemisinic acid synthesis or accumulation. Semi-quantitative reverse-transcriptase (RT)-PCR and quantitative real time-PCR consistently showed that pleiotropic drug resistance (PDR) genes, belonging to the family of ATP-Binding Cassette (ABC) transporter, were massively induced in the yeast strain producing artemisinic acid, relative to the yeast strain producing the hydrocarbon amorphadiene alone. Global transcriptional analysis by yeast

Use of different extracts of coffee pulp for the production of bioethanol.

PubMed

Menezes, Evandro Galvão Tavares; do Carmo, Juliana Ribeiro; Menezes, Aline Galvão Tavares; Alves, José Guilherme Lembi Ferreira; Pimenta, Carlos José; Queiroz, Fabiana

2013-01-01

Coffee is one of the most important agricultural products in Brazil. More than 50 % of the coffee fruit is not used for the production of commercial green coffee and is therefore discarded, usually ending up in the environment. The goal of this work was to select an efficient process for obtaining coffee pulp extract and to evaluate the use of this extract in bioethanol production. The effects of heat treatment and trituration on the yield and composition of the extract were investigated by measuring the amounts of reducing sugars, starch, pectin, and phenolic compounds. The extraction process was most efficient at room temperature using grinding followed by pressing. Five different fermentation media were tested: sugarcane juice or molasses diluted with water or with coffee pulp extract and a medium with only coffee pulp extract. Batch fermentations were carried out at 30 °C for 24 h, and samples were taken to obtain measurements of the total reducing sugars, cell count, and ethanol concentration. The addition of coffee pulp extract did not influence the fermentation or yeast viability, and it can thus be mixed with sugarcane juice or molasses for the production of bioethanol, with a yield of approximately 70 g/L.

Interference of peptone and tyrosine with the lignin peroxidase assay.

PubMed Central

ten Have, R; Hartmans, S; Field, J A

1997-01-01

The N-unregulated white rot fungus Bjerkandera sp. strain BOS55 was cultured in 1 liter of peptone-yeast extract medium to produce lignin peroxidase (LiP). During the LiP assay, the oxidation of veratryl alcohol to veratraldehyde was inhibited due to tyrosine present in the peptone and the yeast extract. PMID:9251220

Antimicrobial and Probiotic Properties of Yeasts: From Fundamental to Novel Applications

PubMed Central

Hatoum, Rima; Labrie, Steve; Fliss, Ismail

2012-01-01

The yeasts constitute a large and heterogeneous group of microorganisms that are currently attracting increased attention from scientists and industry. Numerous and diverse biological activities make them promising candidates for a wide range of applications not limited to the food sector. In addition to their major contribution to flavor development in fermented foods, their antagonistic activities toward undesirable bacteria, and fungi are now widely known. These activities are associated with their competitiveness for nutrients, acidification of their growth medium, their tolerance of high concentrations of ethanol, and release of antimicrobial compounds such as antifungal killer toxins or “mycocins” and antibacterial compounds. While the design of foods containing probiotics (microorganisms that confer health benefits) has focused primarily on Lactobacillus and Bifidobacterium, the yeast Saccharomyces cerevisiae var. boulardii has long been known effective for treating gastroenteritis. In this review, the antimicrobial activities of yeasts are examined. Mechanisms underlying this antagonistic activity as well as recent applications of these biologically active yeasts in both the medical and veterinary sectors are described. PMID:23267352

Immunoprecipitation and Characterization of Membrane Protein Complexes from Yeast

ERIC Educational Resources Information Center

Parra-Belky, Karlett; McCulloch, Kathryn; Wick, Nicole; Shircliff, Rebecca; Croft, Nicolas; Margalef, Katrina; Brown, Jamie; Crabill, Todd; Jankord, Ryan; Waldo, Eric

2005-01-01

In this undergraduate biochemistry laboratory experiment, the vacuolar ATPase protein complex is purified from yeast cell extracts by doing immunoprecipitations under nondenaturing conditions. Immunoprecipitations are performed using monoclonal antibodies to facilitate data interpretation, and subunits are separated on the basis of their molecular…

Interrogation of ethnomedicinal plants for synthetic lethality effects in combination with deficiency in the DNA repair endonuclease RAD1 using a yeast cell-based assay.

PubMed

Aung, Hsu Mon; Huangteerakul, Chananya; Panvongsa, Wittaya; Jensen, Amornrat N; Chairoungdua, Arthit; Sukrong, Suchada; Jensen, Laran T

2018-09-15

Plant materials used in this study were selected based on the ethnobotanical literature. Plants have either been utilized by Thai practitioners as alternative treatments for cancer or identified to exhibit anti-cancer properties. To screen ethnomedicinal plants using a yeast cell-based assay for synthetic lethal interactions with cells deleted for RAD1, the yeast homologue of human ERCC4 (XPF) MATERIALS AND METHODS: Ethanolic extracts from thirty-two species of medicinal plants utilized in Thai traditional medicine were screened for synthetic lethal/sick interactions using a yeast cell-based assay. Cell growth was compared between the parental strain and rad1∆ yeast following exposure to select for specific toxicity of plant extracts. Candidate extracts were further examined for the mode of action using genetic and biochemical approaches. Screening a library of ethanolic extracts from medicinal plants identified Bacopa monnieri and Colubrina asiatica as having synthetic lethal effects in the rad1∆ cells but not the parental strain. Synthetic lethal effects for B. monneiri extracts were more apparent and this plant was examined further. Genetic analysis indicates that pro-oxidant activities and defective excision repair pathways do not significantly contribute to enhanced sensitivity to B. monneiri extracts. Exposure to B. monneiri extracts resulted in nuclear fragmentation and elevated levels of ethidium bromide staining in rad1∆ yeast suggesting promotion of an apoptosis-like event. Growth inhibition also observed in the human Caco-2 cell line suggesting the effects of B. monnieri extracts on both yeast and human cells may be similar. B. monneiri extracts may have utility in treatment of colorectal cancers that exhibit deficiency in ERCC4 (XPF). Copyright © 2018 Elsevier B.V. All rights reserved.

Divergence of Iron Metabolism in Wild Malaysian Yeast

PubMed Central

Lee, Hana N.; Mostovoy, Yulia; Hsu, Tiffany Y.; Chang, Amanda H.; Brem, Rachel B.

2013-01-01

Comparative genomic studies have reported widespread variation in levels of gene expression within and between species. Using these data to infer organism-level trait divergence has proven to be a key challenge in the field. We have used a wild Malaysian population of S. cerevisiae as a test bed in the search to predict and validate trait differences based on observations of regulatory variation. Malaysian yeast, when cultured in standard medium, activated regulatory programs that protect cells from the toxic effects of high iron. Malaysian yeast also showed a hyperactive regulatory response during culture in the presence of excess iron and had a unique growth defect in conditions of high iron. Molecular validation experiments pinpointed the iron metabolism factors AFT1, CCC1, and YAP5 as contributors to these molecular and cellular phenotypes; in genome-scale sequence analyses, a suite of iron toxicity response genes showed evidence for rapid protein evolution in Malaysian yeast. Our findings support a model in which iron metabolism has diverged in Malaysian yeast as a consequence of a change in selective pressure, with Malaysian alleles shifting the dynamic range of iron response to low-iron concentrations and weakening resistance to extreme iron toxicity. By dissecting the iron scarcity specialist behavior of Malaysian yeast, our work highlights the power of expression divergence as a signpost for biologically and evolutionarily relevant variation at the organismal level. Interpreting the phenotypic relevance of gene expression variation is one of the primary challenges of modern genomics. PMID:24142925

Extraction of Pm(III) and Gd(III) by 8-hydroxyquinoline and some related amines in chloroform from nitrate medium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shehata, F.A.; Khalifa, S.M.; El-Dessouky, S.I.

1993-10-01

The extraction of the trivalent radioactive lanthanides (Ln), Pm and Gd from nitrate aqueous medium by 8-hydroxyquinoline (HOX) and/or trilaurylamine (TLA), trioctylamine (TOA), tributylamine (TBA), tripropylamine (TPA) or triallylamine (TAA),L, in chloroform was investigated. The chemical formulae of the extracted organic phase species for both lanthanides were found Ln.NO{sub 3}.(OX){sub 2} for the chelate and Ln.NO{sub 3}(OX){sub 2}.L for the adduct. The respective extraction and formation constants were evaluated. The synergic extraction of Pm and Gd by HOX-amine was investigated as a function of temperature. The thermodynamic parameters, free energy change, enthalpy change and entropy change were evaluated. The stoichiometrymore » of the extracted organic phase species was established and the different data obtained were discussed. 15 refs., 8 figs., 2 tabs.« less

In Vitro Anti-Malassezia Activity of Castanea crenata Shell and Oil-Soluble Glycyrrhiza Extracts.

PubMed

Han, Song Hee; Hur, Min Seok; Kim, Min Jung; Jung, Won Hee; Park, Minji; Kim, Jeong Hwan; Shin, Hong Ju; Choe, Yong Beom; Ahn, Kyu Joong; Lee, Yang Won

2017-06-01

A new shampoo with anti- Malassezia properties obtained from various plants is required to provide seborrheic dermatitis patients with a wider range of treatment options. The aim of this study was to obtain in vitro susceptibility profiles of Malassezia restricta and M. globosa , the most important pathogenic organisms in the development of seborrheic dermatitis, to the plant extracts used in commercial anti-dandruff shampoos. Minimal inhibitory concentrations (MICs) were determined for eight candidate plant extracts and two plant-derived natural products diluted with Leeming and Notman medium to final concentrations of 0.016 to 1 mg/ml. Castanea crenata shell, Camellia sinensis leaf, and oil-soluble Glycyrrhiza extracts presented relatively low MIC values (≤0.5 mg/ml) against both strains. The C. crenata shell and oil-soluble Glycyrrhiza extracts demonstrated especially high anti-Malassezia activity, suggesting their potential use in the treatment of seborrheic dermatitis. The extracts also showed fungistatic activity against other common facultative pathogenic yeasts, Cryptococcus and Candida . C. crenata shell and oil-soluble Glycyrrhiza extracts could potentially be used as active ingredients in anti-seborrheic and anti-dandruff shampoo formulations. They could be helpful for repeated treatments and regular prophylaxis of scalp seborrheic dermatitis.

Effects of SNF1 on Maltose Metabolism and Leavening Ability of Baker's Yeast in Lean Dough.

PubMed

Zhang, Cui-Ying; Bai, Xiao-Wen; Lin, Xue; Liu, Xiao-Er; Xiao, Dong-Guang

2015-12-01

Maltose metabolism of baker's yeast (Saccharomyces cerevisiae) in lean dough is negatively influenced by glucose repression, thereby delaying the dough fermentation. To improve maltose metabolism and leavening ability, it is necessary to alleviate glucose repression. The Snf1 protein kinase is well known to be essential for the response to glucose repression and required for transcription of glucose-repressed genes including the maltose-utilization genes (MAL). In this study, the SNF1 overexpression and deletion industrial baker's yeast strains were constructed and characterized in terms of maltose utilization, growth and fermentation characteristics, mRNA levels of MAL genes (MAL62 encoding the maltase and MAL61 encoding the maltose permease) and maltase and maltose permease activities. Our results suggest that overexpression of SNF1 was effective to glucose derepression for enhancing MAL expression levels and enzymes (maltase and maltose permease) activities. These enhancements could result in an 18% increase in maltose metabolism of industrial baker's yeast in LSMLD medium (the low sugar model liquid dough fermentation medium) containing glucose and maltose and a 15% increase in leavening ability in lean dough. These findings provide a valuable insight of breeding industrial baker's yeast for rapid fermentation. © 2015 Institute of Food Technologists®

Copper-tolerant yeasts: Raman spectroscopy in determination of bioaccumulation mechanism.

PubMed

Radić, Danka S; Pavlović, Vera P; Lazović, Milana M; Jovičić-Petrović, Jelena P; Karličić, Vera M; Lalević, Blažo T; Raičević, Vera B

2017-09-01

Modern, efficient, and cost-effective approach to remediation of heavy metal-contaminated soil is based on the application of microorganisms. In this paper, four isolates from agricultural and urban contaminated soil showed abundant growth in the presence of copper(II) sulfate pentahydrate (CuSO 4 ·5H 2 O) up to 2 mM. Selected yeasts were identified by molecular methods as Candida tropicalis (three isolates) and Schwanniomyces occidentalis (one isolate). C. tropicalis (4TD1101S) showed the highest percentage of bioaccumulation capabilities (94.37%), determined by the inductively coupled plasma optical emission spectrometry (ICP-OES). The Raman spectra of C. tropicalis (4TD1101S) analyzed in a medium with the addition of 2 mM CuSO 4 ·5H 2 O showed certain increase in metallothionein production, which represents a specific response of the yeast species to the stress conditions. These results indicate that soil yeasts represent a potential for practical application in the bioremediation of contaminated environments.

Yeast Based Sensors

NASA Astrophysics Data System (ADS)

Shimomura-Shimizu, Mifumi; Karube, Isao

Since the first microbial cell sensor was studied by Karube et al. in 1977, many types of yeast based sensors have been developed as analytical tools. Yeasts are known as facultative anaerobes. Facultative anaerobes can survive in both aerobic and anaerobic conditions. The yeast based sensor consisted of a DO electrode and an immobilized omnivorous yeast. In yeast based sensor development, many kinds of yeast have been employed by applying their characteristics to adapt to the analyte. For example, Trichosporon cutaneum was used to estimate organic pollution in industrial wastewater. Yeast based sensors are suitable for online control of biochemical processes and for environmental monitoring. In this review, principles and applications of yeast based sensors are summarized.

Inhibitive effect of Xylopia ferruginea extract on the corrosion of mild steel in 1M HCl medium

NASA Astrophysics Data System (ADS)

Raja, Pandian Bothi; Rahim, Afidah Abdul; Osman, Hasnah; Awang, Khalijah

2011-08-01

The alkaloid content of the leaves and stem bark of Xylopia ferruginea plant was isolated and tested for its anticorrosion potential on mild steel corrosion in a hydrochloric acid medium by using electrochemical impedance spectroscopy, potentiodynamic polarization measurement, scanning electron microscopy (SEM), and Fourier transform infra red (FTIR) analysis. The experimental results reveal the effective anticorrosion potential of the plant extract. The mixed mode of action exhibited by the plant extract is evidenced from the polarization study. SEM images proof the formation of a protective layer over the mild steel surface, and this is supported by the FTIR study. The possible mode of the corrosion inhibition mechanism has also been discussed.

Stress tolerance and biocontrol performance of the yeast antagonist, Candida diversa, change with morphology transition.

PubMed

Li, Guangkun; Chi, Mengshan; Chen, Huizhen; Sui, Yuan; Li, Yan; Liu, Yongsheng; Zhang, Xiaojing; Sun, Zhiqiang; Liu, Guoqing; Wang, Qi; Liu, Jia

2016-02-01

As an eco-friendly management method, biological control of postharvest diseases, utilizing antagonistic yeasts, is a research topic receiving considerable attention. Detailed knowledge on the biology of yeast antagonists is crucial when considering their potential application and development as biocontrol products. Changes in the growth form, such as single-cell to pseudohyphae, have been associated with the mode of action in postharvest biocontrol yeasts. In this study, the antagonistic yeast, Candida diversa, reversibly shifted from a single-cell morphology on yeast peptone dextrose (YPD) medium with 2 % agar to a pseudohyphal morphology on YPD with 0.3 % agar. The tolerance of the pseudohyphal form to heat and oxidative stresses, as well as the biocontrol efficacy against Botrytis cinerea on apple and kiwifruit stored at 25 and 4 °C, was significantly higher as compared to the single-cell form. This study provides new information on the ability of C. diversa to change its morphology and the impact of the morphology shift on stress tolerance and biocontrol performance.

Optimization of critical medium components using response surface methodology for biomass and extracellular polysaccharide production by Agaricus blazei.

PubMed

Liu, Gao-Qiang; Wang, Xiao-Ling

2007-02-01

Response surface methodology (RSM) was applied to optimize the critical medium ingredients of Agaricus blazei. A three-level Box-Behnken factorial design was employed to determine the maximum biomass and extracellular polysaccharide (EPS) yields at optimum levels for glucose, yeast extract (YE), and peptone. A mathematical model was then developed to show the effect of each medium composition and its interactions on the production of mycelial biomass and EPS. The model predicted the maximum biomass yield of 10.86 g/l that appeared at glucose, YE, peptone of 26.3, 6.84, and 6.62 g/l, respectively, while a maximum EPS yield of 348.4 mg/l appeared at glucose, YE, peptone of 28.4, 4.96, 5.60 g/l, respectively. These predicted values were also verified by validation experiments. The excellent correlation between predicted and measured values of each model justifies the validity of both the response models. The results of bioreactor fermentation also show that the optimized culture medium enhanced both biomass (13.91 +/- 0.71 g/l) and EPS (363 +/- 4.1 mg/l) production by Agaricus blazei in a large-scale fermentation process.

Uranium bioprecipitation mediated by yeasts utilizing organic phosphorus substrates.

PubMed

Liang, Xinjin; Csetenyi, Laszlo; Gadd, Geoffrey Michael

2016-06-01

In this research, we have demonstrated the ability of several yeast species to mediate U(VI) biomineralization through uranium phosphate biomineral formation when utilizing an organic source of phosphorus (glycerol 2-phosphate disodium salt hydrate (C3H7Na2O6P·xH2O (G2P)) or phytic acid sodium salt hydrate (C6H18O24P6·xNa(+)·yH2O (PyA))) in the presence of soluble UO2(NO3)2. The formation of meta-ankoleite (K2(UO2)2(PO4)2·6(H2O)), chernikovite ((H3O)2(UO2)2(PO4)2·6(H2O)), bassetite (Fe(++)(UO2)2(PO4)2·8(H2O)), and uramphite ((NH4)(UO2)(PO4)·3(H2O)) on cell surfaces was confirmed by X-ray diffraction in yeasts grown in a defined liquid medium amended with uranium and an organic phosphorus source, as well as in yeasts pre-grown in organic phosphorus-containing media and then subsequently exposed to UO2(NO3)2. The resulting minerals depended on the yeast species as well as physico-chemical conditions. The results obtained in this study demonstrate that phosphatase-mediated uranium biomineralization can occur in yeasts supplied with an organic phosphate substrate as sole source of phosphorus. Further understanding of yeast interactions with uranium may be relevant to development of potential treatment methods for uranium waste and utilization of organic phosphate sources and for prediction of microbial impacts on the fate of uranium in the environment.

Yarrowia lipolytica: a model yeast for citric acid production.

PubMed

Cavallo, Ema; Charreau, Hernán; Cerrutti, Patricia; Foresti, María Laura

2017-12-01

Every year more than 2 million tons of citric acid (CA) are produced around the world for industrial uses. Although initially extracted from citrus, the low profitability of the process and the increasing demand soon stimulated the search for more efficient methods to produce CA. Currently, most world CA demand (99%) is satisfied by fermentations with microorganisms, especially filamentous fungi and yeasts. CA production with yeasts has certain advantages over molds (e.g. higher productivity and easier cultivation), which in the last two decades have triggered a clear increase in publications and patents devoted to the use of yeasts in this field. Yarrowia lipolytica has become a model yeast that proved to be successful in different production systems. Considering the current interest evidenced in the literature, the most significant information on CA production using Y. lipolytica is summarized. The relevance on CA yields of key factors such as strains, media formulation, environmental conditions and production regimes is thoroughly discussed, with particular focus on increasing CA productivity. Besides, the possibility of tuning the mentioned variables to reduce concomitant isocitric acid production-the biggest disadvantage of using yeasts-is analyzed. Available methods for CA purification/quantification are also discussed. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Improvement in extracellular protease production by the marine antarctic yeast Rhodotorula mucilaginosa L7.

PubMed

Chaud, Luciana C S; Lario, Luciana D; Bonugli-Santos, Rafaella C; Sette, Lara D; Pessoa Junior, Adalberto; Felipe, Maria das Graças de A

2016-12-25

Microorganisms from extreme and restrictive eco systems, such as the Antarctic continent, are of great interest due to their ability to synthesize products of commercial value. Among these, enzymes from psychrotolerant and psychrophilic microorganisms offer potential economical benefits due to their high activity at low and moderate temperatures. The cold adapted yeast Rhodotorula mucilaginosa L7 was selected out of 97 yeasts isolated from Antarctica as having the highest extracellular proteolytic activity in preliminary tests. The present study was aimed at evaluating the effects of nutrient composition (peptone, rice bran extract, ammonium sulfate, sodium chloride) and physicochemical parameters (temperature and pH) on its proteolytic activity. A 2 6-2 fractional factorial design experiment followed by a central composite design (CCD 2 3 ) was performed to optimize the culture conditions and improve the extracellular proteolytic activity. The results indicated that the presence of peptone in the medium was the most influential factor in protease production. Enzymatic activity was enhanced by the interaction between low glucose and peptone concentrations. The optimization of culture conditions with the aid of mathematical modeling enabled a c. 45% increase in proteolytic activity and at the same time reduced the amount of glucose and peptone required for the culture. Thus culture conditions established in this work may be employed in the biotechnological production of this protease. Copyright © 2016 Elsevier B.V. All rights reserved.

CHROMagar Candida Medium for Direct Susceptibility Testing of Yeast from Blood Cultures

PubMed Central

Tan, Grace L.; Peterson, Ellena M.

2005-01-01

An evaluation was performed on 95 blood cultures positive for Candida spp. to determine the correlation of direct susceptibility testing of fluconazole versus both standardized disk diffusion and MIC methods. For direct testing, an aliquot taken from BD BACTEC Plus and/or BD BACTEC Lytic/10 bottles (Becton Dickinson [BD], Sparks, MD) positive by gram stain for yeast was subcultured to CHROMagar Candida (BD), and a 25-μg fluconazole disk (BD) was placed on the plate. The area of growth inhibition surrounding the disk was measured at 24 and 48 h. In addition, a subculture of the isolate was tested by a microdilution MIC using YeastOne (TREK Diagnostics Systems Inc., OH) and disk diffusion (NCCLS M44-A) using a standardized inoculum plated onto CHROMagar Candida as well as Mueller-Hinton agar to which 2% glucose and 0.5 μg/ml methylene blue dye was added (MH-GMB). The categorical interpretation derived from the MIC was used as the reference to which the disk diffusion results were compared. There were a total of 41 Candida albicans, 23 Candida glabrata, 20 Candida parapsilosis, 9 Candida tropicalis, and 1 each of Candida krusei and Candida lusitaniae tested. At 24 h there was full agreement among the methods for all C. albicans, C. tropicalis, C. lusitaniae, and C. krusei isolates. For the C. parapsilosis isolates at 24 h there was one very major discrepancy using the direct CHROMagar and one major error with the standardized MH-GMB. The majority of the errors were seen at 24 h with the C. glabrata isolates. Of the 23 C. glabrata isolates at 24 h by direct CHROMagar, there were 10 minor and 1 very major error; by MH-GMB there were 12 minor and 2 very major errors; and by standardized CHROMagar Candida there were 13 minor and 2 major errors. There were no very major errors with C. glabrata when all plates were read at 48 h. At 24 h by the direct and standardized CHROMagar the majority of C. glabrata isolates were more resistant, whereas by MH-GMB they were more

Extracellular Polysaccharides Produced by Yeasts and Yeast-Like Fungi

NASA Astrophysics Data System (ADS)

van Bogaert, Inge N. A.; de Maeseneire, Sofie L.; Vandamme, Erick J.

Several yeasts and yeast-like fungi are known to produce extracellular polysaccharides. Most of these contain D-mannose, either alone or in combination with other sugars or phosphate. A large chemical and structural variability is found between yeast species and even among different strains. The types of polymers that are synthesized can be chemically characterized as mannans, glucans, phosphoman-nans, galactomannans, glucomannans and glucuronoxylomannans. Despite these differences, almost all of the yeast exopolysaccharides display some sort of biological activity. Some of them have already applications in chemistry, pharmacy, cosmetics or as probiotic. Furthermore, some yeast exopolysaccharides, such as pullulan, exhibit specific physico-chemical and rheological properties, making them useful in a wide range of technical applications. A survey is given here of the production, the characteristics and the application potential of currently well studied yeast extracellular polysaccharides.

Yeast Infection (Vaginal)

MedlinePlus

Yeast infection (vaginal) Overview A vaginal yeast infection is a fungal infection that causes irritation, discharge and intense itchiness ... symptoms Causes The fungus candida causes a vaginal yeast infection. Your vagina naturally contains a balanced mix of yeast, including ...

Immobilization of microbial cell and yeast cell and its application to biomass conversion using radiation techniques

NASA Astrophysics Data System (ADS)

Kaetsu, Isao; Kumakura, Minoru; Fujimura, Takashi; Kasai, Noboru; Tamada, Masao

The recent results of immobilization of cellulase-producing cells and ethanol-fermentation yeast by radiation were reported. The enzyme of cellulase produced by immobilized cells was used for saccharification of lignocellulosic wastes and immobilized yeast cells were used for fermentation reaction from glucose to ethanol. The wastes such as chaff and bagasse were treated by γ-ray or electron-beam irradiation in the presence of alkali and subsequent mechanical crushing, to form a fine powder less than 50 μm in diameter. On the other hand, Trichoderma reesei as a cellulase-producing microbial cell was immobilized on a fibrous carrier having a specific porous structure and cultured to produce cellulase. The enzymatic saccharification of the pretreated waste was carried out using the produced cellulase. The enhanced fermentation process to produce ethanol from glucose with the immobilized yeast by radiation was also studied. The ethanol productivity of immobilized growing yeast cells thus obtained was thirteen times that of free yeast cells in a 1:1 volume of liquid medium to immobilized yeast cells.

Alpha-ketoglutarate enhances freeze-thaw tolerance and prevents carbohydrate-induced cell death of the yeast Saccharomyces cerevisiae.

PubMed

Bayliak, Maria M; Hrynkiv, Olha V; Knyhynytska, Roksolana V; Lushchak, Volodymyr I

2018-01-01

Stress resistance and fermentative capability are important quality characteristics of baker's yeast. In the present study, we examined protective effects of exogenous alpha-ketoglutarate (AKG), an intermediate of the tricarboxylic acid cycle and amino acid metabolism, against freeze-thaw and carbohydrate-induced stresses in the yeast Saccharomyces cerevisiae. Growth on AKG-supplemented medium prevented a loss of viability and improved fermentative capacity of yeast cells after freeze-thaw treatment. The cells grown in the presence of AKG had higher levels of amino acids (e.g., proline), higher metabolic activity and total antioxidant capacity, and higher activities of catalase, NADP-dependent glutamate dehydrogenase and glutamine synthase compared to control ones. Both synthesis of amino acids and enhancement of antioxidant system capacity could be involved in AKG-improved freeze-thaw tolerance in S. cerevisiae. Cell viability dramatically decreased under incubation of stationary-phase yeast cells in 2% glucose or fructose solutions (in the absence of the other nutrients) as compared with incubation in distilled water or in 10 mM AKG solution. The decrease in cell viability was accompanied by acidification of the medium, and decrease in cellular respiration, aconitase activity, and levels of total protein and free amino acids. The supplementation with 10 mM AKG effectively prevented carbohydrate-induced yeast death. Protective mechanisms of AKG could be associated with the intensification of respiration and prevention of decreasing protein level as well as with direct antioxidant AKG action.

Exopolysaccharides from yeast: insight into optimal conditions for biosynthesis, chemical composition and functional properties - review.

PubMed

Gientka, Iwona; Błażejak, Stanisław; Stasiak-Różańska, Lidia; Chlebowska-Śmigiel, Anna

2015-01-01

xopolysaccharides (EPS) are not a well-established group of metabolites. An industrial scale    of this EPS production is limited mainly by low yield biosynthesis. Until now, enzymes and biosynthesis pathways, as well as the role of regulatory genes, have not been described. Some of yeast EPS show antitumor, immunostimulatory and antioxidant activity. Others, absorb heavy metals and can function as bioactive components of food. Also, the potential of yeast EPS as thickeners or stabilizers can be found. Optimal conditions for the biosynthesis of yeast exopolysaccharides require strong oxygenation and low temperature of the culture, due to the physiology of the producer strains. The medium should contain sucrose as a carbon source and ammonium sulfate as inorganic nitrogen source, wherein the C:N ratio in the substrate should be 15:1. The cultures are long and the largest accumulation of polymers is observed after 4 or 5 days of culturing. The structure of yeast EPS is complex which affects the strain and culture condition. The EPS from yeast are linear mannans, pullulan, glucooligosaccharides, galactooligosaccharides and other heteropolysaccharides containing α-1,2; α-1,3; α-1,6; β-1,3; β-1,4 bonds. Mannose and glucose have the largest participation of carbohydrates for. t exopolysaccharides (EPS) are not a well-established group of metabolites. An industrial scale    of this EPS production is limited mainly by low yield biosynthesis. Until now, enzymes and biosynthesis pathways, as well as the role of regulatory genes, have not been described. Some of yeast EPS show antitumor, immunostimulatory and antioxidant activity. Others, absorb heavy metals and can function as bioactive components of food. Also, the potential of yeast EPS as thickeners or stabilizers can be found. Optimal conditions for the biosynthesis of yeast exopolysaccharides require strong oxygenation and low temperature of the culture, due to the physiology of the producer strains. The

Proteomic evolution of a wine yeast during the first hours of fermentation.

PubMed

Salvadó, Zoel; Chiva, Rosana; Rodríguez-Vargas, Sonia; Rández-Gil, Francisca; Mas, Albert; Guillamón, José Manuel

2008-11-01

The inoculation of active dry wine yeast (ADWY) is one of the most common practices in winemaking. This inoculation exposes the yeast cells to strong osmotic, acidic and thermal stresses, and adaptation to the new medium is crucial for successful fermentation. We have analysed the changes that occur in the ADWY protein profile in the first hours after inoculation under enological-like conditions at a low temperature. Protein changes mainly included enzymes of the nitrogen and carbon metabolism and proteins related to the cellular stress response. Most of the enzymes of the lower part of the glycolysis showed an increase in their concentration 4 and 24 h after inoculation, indicating an increase in glycolytic flux and in ATP production. However, the shift from respiration to fermentation was not immediate in the inoculation because some mitochondrial proteins involved in oxidative metabolism were induced in the first hours after inoculation. Inoculation in this fresh medium also reduced the cellular concentration of stress proteins produced during industrial production of the ADWY. The only exception was Cys3p, which might be involved in glutathione synthesis as a response to oxidative stress. A better understanding of the yeast stress response to rehydration and inoculation will lead to improvements in the handling efficiency of ADWY in winemaking and presumably to better control of fermentation startup.

Binding mechanism of patulin to heat-treated yeast cell.

PubMed

Guo, C; Yuan, Y; Yue, T; Hatab, S; Wang, Z

2012-12-01

This study aims to assess the removal mechanism of patulin using heat-treated Saccharomyces cerevisiae cells and identify the role of different cell wall components in the binding process. In order to understand the binding mechanism, viable cells, heat-treated cells, cell wall and intracellular extract were performed to assess their ability to remove patulin. Additionally, the effects of chemical and enzymatic treatments of yeast on the binding ability were tested. The results showed that there was no significant difference between viable (53·28%) and heat-treated yeast cells (51·71%) in patulin binding. In addition, the cell wall fraction decreased patulin by 35·05%, and the cell extract nearly failed to bind patulin. Treatments with protease E, methanol, formaldehyde, periodate or urea significantly decreased (P < 0·05) the ability of heat-treated cells to remove patulin. Fourier transform infrared (FTIR) analysis indicated that more functional groups were involved in the binding process of heat-treated cells. Polysaccharides and protein are important components of yeast cell wall involved in patulin removal. In addition, hydrophobic interactions play a major role in binding processes. Heat-treated S. cerevisiae cells could be used to control patulin contamination in the apple juice industry. Also, our results proof that the patulin removal process is based mainly on the adsorption not degradation. © 2012 The Society for Applied Microbiology.

Distinct Domestication Trajectories in Top-Fermenting Beer Yeasts and Wine Yeasts.

PubMed

Gonçalves, Margarida; Pontes, Ana; Almeida, Pedro; Barbosa, Raquel; Serra, Marta; Libkind, Diego; Hutzler, Mathias; Gonçalves, Paula; Sampaio, José Paulo

2016-10-24

Beer is one of the oldest alcoholic beverages and is produced by the fermentation of sugars derived from starches present in cereal grains. Contrary to lager beers, made by bottom-fermenting strains of Saccharomyces pastorianus, a hybrid yeast, ale beers are closer to the ancient beer type and are fermented by S. cerevisiae, a top-fermenting yeast. Here, we use population genomics to investigate (1) the closest relatives of top-fermenting beer yeasts; (2) whether top-fermenting yeasts represent an independent domestication event separate from those already described; (3) whether single or multiple beer yeast domestication events can be inferred; and (4) whether top-fermenting yeasts represent non-recombinant or recombinant lineages. Our results revealed that top-fermenting beer yeasts are polyphyletic, with a main clade composed of at least three subgroups, dominantly represented by the German, British, and wheat beer strains. Other beer strains were phylogenetically close to sake, wine, or bread yeasts. We detected genetic signatures of beer yeast domestication by investigating genes previously linked to brewing and using genome-wide scans. We propose that the emergence of the main clade of beer yeasts is related with a domestication event distinct from the previously known cases of wine and sake yeast domestication. The nucleotide diversity of the main beer clade more than doubled that of wine yeasts, which might be a consequence of fundamental differences in the modes of beer and wine yeast domestication. The higher diversity of beer strains could be due to the more intense and different selection regimes associated to brewing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mutagenizing brewing yeast strain for improving fermentation property of beer.

PubMed

Liu, Zengran; Zhang, Guangyi; Sun, Yunping

2008-07-01

A brewing yeast mutant with perfect sugar fermentation capacity was isolated by mutagenizing the Saccharomyces pastorianus transformant, which carries an integrated glucoamylase gene and has one copy of non-functional alpha-acetolactate synthase gene. The mutant was able to utilize maltotriose efficiently, and the maltotriose fermentability in YNB-2% maltotriose medium increased from 32.4% to 72.0% after 5 d in shaking culture. The wort fermentation test confirmed that the sugar fermentation property of the mutant was greatly improved, while its brewing performances were analogous to that of the wild-type strain and the characteristic trait of shortened beer maturation period was retained. Therefore, we believe that the brewing yeast mutant would benefit the beer industry and would be useful for low caloric beer production.

Yeast effects on Pinot noir wine phenolics, color, and tannin composition.

PubMed

Carew, Anna L; Smith, Paul; Close, Dugald C; Curtin, Chris; Dambergs, Robert G

2013-10-16

Extraction and stabilization of wine phenolics can be challenging for wine makers. This study examined how yeast choice affected phenolic outcomes in Pinot noir wine. Five yeast treatments were applied in replicated microvinification, and wines were analyzed by UV-visible spectrophotometry. At bottling, yeast treatment Saccharomyces cerevisiae RC212 wine had significantly higher concentrations of total pigment, free anthocyanin, nonbleachable pigment, and total tannin and showed high color density. Some phenolic effects were retained at 6 months' bottle age, and RC212 and S. cerevisae EC1118 wines showed increased mean nonbleachable pigment concentrations. Wine tannin composition analysis showed three treatments were associated with a higher percentage of trihydroxylated subunits (skin tannin indicator). A high degree of tannin polymerization was observed in wines made with RC212 and Torulaspora delbruekii , whereas tannin size by gel permeation chromatography was higher only in the RC212 wines. The results emphasize the importance of yeast strain choice for optimizing Pinot noir wine phenolics.

Lipid Content and Cryotolerance of Bakers' Yeast in Frozen Doughs †

PubMed Central

Gélinas, Pierre; Fiset, Gisèle; Willemot, Claude; Goulet, Jacques

1991-01-01

The relationship between lipid content and tolerance to freezing at −50°C was studied in Saccharomyces cerevisiae grown under batch or fed-batch mode and various aeration and temperature conditions. A higher free-sterol-to-phospholipid ratio as well as higher free sterol and phospholipid contents correlated with the superior cryoresistance in dough or in water of the fed-batch-grown compared with the batch-grown cells. For both growth modes, the presence of excess dissolved oxygen in the culture medium greatly improved yeast cryoresistance and trehalose content (P. Gélinas, G. Fiset, A. LeDuy, and J. Goulet, Appl. Environ. Microbiol. 26:2453-2459, 1989) without significantly changing the lipid profile. Under the batch or fed-batch modes, no correlation was found between the cryotolerance of bakers' yeast and the total cellular lipid content, the total sterol content, the phospholipid unsaturation index, the phosphate or crude protein content, or the yeast cell morphology (volume and roundness). PMID:16348412

Saccharomyces cerevisiae Produces a Yeast Substance that Exhibits Estrogenic Activity in Mammalian Systems

NASA Astrophysics Data System (ADS)

Feldman, David; Stathis, Peter A.; Hirst, Margaret A.; Price Stover, E.; Do, Yung S.; Kurz, Walter

1984-06-01

Partially purified lipid extracts of Saccharomyces cerevisiae contain a substance that displaces tritiated estradiol from rat uterine cytosol estrogen receptors. The yeast product induces estrogenic bioresponses in mammalian systems as measured by induction of progesterone receptors in cultured MCF-7 human breast cancer cells and by a uterotrophic response and progesterone receptor induction after administration to ovariectomized mice. The findings raise the possibility that bakers' yeast may be a source of environmental estrogens.

Biofortification of folates in white wheat bread by selection of yeast strain and process.

PubMed

Hjortmo, Sofia; Patring, Johan; Jastrebova, Jelena; Andlid, Thomas

2008-09-30

We here demonstrate that folate content in yeast fermented food can be dramatically increased by using a proper (i) yeast strain and (ii) cultivation procedure for the selected strain prior to food fermentation. Folate levels were 3 to 5-fold higher in white wheat bread leavened with a Saccharomyces cerevisiae strain CBS7764, cultured in defined medium and harvested in the respiro-fermentative phase of growth prior to dough preparation (135-139 microg/100 dry matter), compared to white wheat bread leavened with commercial Baker's yeast (27-43 microg/100 g). The commercial Baker's yeast strain had been industrially produced, using a fed-batch process, thereafter compressed and stored in the refrigerator until bakings were initiated. This strategy is an attractive alternative to fortification of bread with synthetically produced folic acid. By using a high folate producing strain cultured a suitable way folate levels obtained were in accordance with folic acid content in fortified cereal products.

Increase of ethanol productivity by cell-recycle fermentation of flocculating yeast.

PubMed

Wang, F Z; Xie, T; Hui, M

2011-01-01

Using the recombinant flocculating Angel yeast F6, long-term repeated batch fermentation for ethanol production was performed and a high volumetric productivity resulted from half cells not washed and the optimum opportunity of residual glucose 20 g l(-1) of last medium. The obtained highest productivity was 2.07 g l-(1) h(-1), which was improved by 75.4% compared with that of 1.18 g l(-1) h(-1) in the first batch fermentation. The ethanol concentration reached 8.4% corresponding to the yield of 0.46 g g(-1). These results will contribute greatly to the industrial production of fuel ethanol using the commercial method with the flocculating yeast.

Study of the effectiveness of propolis extract as a storage medium for avulsed teeth.

PubMed

Casaroto, Ana Regina; Hidalgo, Mirian Marubayashi; Sell, Ana Maria; Franco, Selma Lucy; Cuman, Roberto Kenji Nakamura; Moreschi, Eduardo; Victorino, Fausto Rodrigo; Steffens, Vânia Antunes; Bersani-Amado, Ciomar Aparecida

2010-08-01

The purpose of the present study was to evaluate the efficacy of propolis extract in maintaining the viability of human periodontal ligament (PDL) cells, and to radiographically analyze tooth replantation and the adjacent periodontium in dogs after storage in this extract. Human PDL cells were incubated with the experimental media propolis, milk, saliva, Hank's balanced salt solution (HBSS), and Dulbecco's modified Eagles medium (DMEM, positive controls), and distilled water (negative control). Cell viability was determined 0, 1, 3, 6, 12, and 24 h later by colorimetric MTT assay. Thirty incisors from dogs were divided into two storage time blocks (1 and 3 h) and were maintained in the experimental media. HBSS served as a positive control, and dry teeth (on gauze) as a negative control. The replanted teeth were radiographed once per month for 6 months. The radiographic images were standardized by the shortening/lengthening factor, and were both qualitatively and quantitatively analyzed. The in vitro results showed that the efficacy of propolis in maintaining functional viability of PDL cells was similar to that of milk. Propolis and milk were significantly better than controls from the 6-h time period. The in vivo results showed that teeth maintained in propolis medium exhibited replacement resorption with significant reduction in tooth length, similar to teeth maintained in saliva and dried teeth. This resorption was less intense with the 3-h storage time than the 1-h storage time. Conditions close to normal were found in teeth maintained in milk, similar to the HBSS control. Therefore, although propolis was effective in maintaining the viability of human PDL cells, resorption of the tooth replantation in dogs occurred under these experimental conditions.

Use of flow cytometry to monitor cell damage and predict fermentation activity of dried yeasts.

PubMed

Attfield, P V; Kletsas, S; Veal, D A; van Rooijen, R; Bell, P J

2000-08-01

Viable dried yeast is used as an inoculum for many fermentations in the baking and wine industries. The fermentative activity of yeast in bread dough or grape must is a critical parameter of process efficiency. Here, it is shown that fluorescent stains and flow cytometry can be used in concert to predict the abilities of populations of dried bakers' and wine yeasts to ferment after rehydration. Fluorescent dyes that stain cells only if they have damaged membrane potential (oxonol) or have increased membrane permeability (propidium iodide) were used to analyse, by flow cytometry, populations of rehydrated yeasts. A strong relationship (r2 = 0.99) was found between the percentages of populations staining with the oxonol and the degree of cell membrane damage as measured by the more traditional method of leakage of intracellular compounds. There were also were good negative relationships (r2 > or = 0.83) between fermentation by rehydrated bakers' or wine dry yeasts and percentage of populations staining with either oxonol or propidium iodide. Fluorescent staining with flow cytometry confirmed that factors such as vigour of dried yeast mixing in water, soaking before stirring, rehydration in water or fermentation medium and temperature of rehydration have profound effects on subsequent yeast vitality. These experiments indicate the potential of flow cytometry as a rapid means of predicting the fermentation performance of dried bakers' and wine yeasts.

Advancing secondary metabolite biosynthesis in yeast with synthetic biology tools.

PubMed

Siddiqui, Michael S; Thodey, Kate; Trenchard, Isis; Smolke, Christina D

2012-03-01

Secondary metabolites are an important source of high-value chemicals, many of which exhibit important pharmacological properties. These valuable natural products are often difficult to synthesize chemically and are commonly isolated through inefficient extractions from natural biological sources. As such, they are increasingly targeted for production by biosynthesis from engineered microorganisms. The budding yeast species Saccharomyces cerevisiae has proven to be a powerful microorganism for heterologous expression of biosynthetic pathways. S. cerevisiae's usefulness as a host organism is owed in large part to the wealth of knowledge accumulated over more than a century of intense scientific study. Yet many challenges are currently faced in engineering yeast strains for the biosynthesis of complex secondary metabolite production. However, synthetic biology is advancing the development of new tools for constructing, controlling, and optimizing complex metabolic pathways in yeast. Here, we review how the coupling between yeast biology and synthetic biology is advancing the use of S. cerevisiae as a microbial host for the construction of secondary metabolic pathways. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Enhancement of ethanol fermentation in Saccharomyces cerevisiae sake yeast by disrupting mitophagy function.

PubMed

Shiroma, Shodai; Jayakody, Lahiru Niroshan; Horie, Kenta; Okamoto, Koji; Kitagaki, Hiroshi

2014-02-01

Saccharomyces cerevisiae sake yeast strain Kyokai no. 7 has one of the highest fermentation rates among brewery yeasts used worldwide; therefore, it is assumed that it is not possible to enhance its fermentation rate. However, in this study, we found that fermentation by sake yeast can be enhanced by inhibiting mitophagy. We observed mitophagy in wild-type sake yeast during the brewing of Ginjo sake, but not when the mitophagy gene (ATG32) was disrupted. During sake brewing, the maximum rate of CO2 production and final ethanol concentration generated by the atg32Δ laboratory yeast mutant were 7.50% and 2.12% higher than those of the parent strain, respectively. This mutant exhibited an improved fermentation profile when cultured under limiting nutrient concentrations such as those used during Ginjo sake brewing as well as in minimal synthetic medium. The mutant produced ethanol at a concentration that was 2.76% higher than the parent strain, which has significant implications for industrial bioethanol production. The ethanol yield of the atg32Δ mutant was increased, and its biomass yield was decreased relative to the parent sake yeast strain, indicating that the atg32Δ mutant has acquired a high fermentation capability at the cost of decreasing biomass. Because natural biomass resources often lack sufficient nutrient levels for optimal fermentation, mitophagy may serve as an important target for improving the fermentative capacity of brewery yeasts.

Enhancement of Ethanol Fermentation in Saccharomyces cerevisiae Sake Yeast by Disrupting Mitophagy Function

PubMed Central

Shiroma, Shodai; Jayakody, Lahiru Niroshan; Horie, Kenta; Okamoto, Koji

2014-01-01

Saccharomyces cerevisiae sake yeast strain Kyokai no. 7 has one of the highest fermentation rates among brewery yeasts used worldwide; therefore, it is assumed that it is not possible to enhance its fermentation rate. However, in this study, we found that fermentation by sake yeast can be enhanced by inhibiting mitophagy. We observed mitophagy in wild-type sake yeast during the brewing of Ginjo sake, but not when the mitophagy gene (ATG32) was disrupted. During sake brewing, the maximum rate of CO2 production and final ethanol concentration generated by the atg32Δ laboratory yeast mutant were 7.50% and 2.12% higher than those of the parent strain, respectively. This mutant exhibited an improved fermentation profile when cultured under limiting nutrient concentrations such as those used during Ginjo sake brewing as well as in minimal synthetic medium. The mutant produced ethanol at a concentration that was 2.76% higher than the parent strain, which has significant implications for industrial bioethanol production. The ethanol yield of the atg32Δ mutant was increased, and its biomass yield was decreased relative to the parent sake yeast strain, indicating that the atg32Δ mutant has acquired a high fermentation capability at the cost of decreasing biomass. Because natural biomass resources often lack sufficient nutrient levels for optimal fermentation, mitophagy may serve as an important target for improving the fermentative capacity of brewery yeasts. PMID:24271183

Relationship between pH and Medium Dissolved Solids in Terms of Growth and Metabolism of Lactobacilli and Saccharomyces cerevisiae during Ethanol Production

PubMed Central

Narendranath, Neelakantam V.; Power, Ronan

2005-01-01

The specific growth rates of four species of lactobacilli decreased linearly with increases in the concentration of dissolved solids (sugars) in liquid growth medium. This was most likely due to the osmotic stress exerted by the sugars on the bacteria. The reduction in growth rates corresponded to decreased lactic acid production. Medium pH was another factor studied. As the medium pH decreased from 5.5 to 4.0, there was a reduction in the specific growth rate of lactobacilli and a corresponding decrease in the lactic acid produced. In contrast, medium pH did not have any significant effect on the specific growth rate of yeast at any particular concentration of dissolved solids in the medium. However, medium pH had a significant (P < 0.001) effect on ethanol production. A medium pH of 5.5 resulted in maximal ethanol production in all media with different concentrations of dissolved solids. When the data were analyzed as a 4 (pH levels) by 4 (concentrations of dissolved solids) factorial experiment, there was no synergistic effect (P > 0.2923) observed between pH of the medium and concentration of dissolved solids of the medium in reducing bacterial growth and metabolism. The data suggest that reduction of initial medium pH to 4.0 for the control of lactobacilli during ethanol production is not a good practice as there is a reduction (P < 0.001) in the ethanol produced by the yeast at pH 4.0. Setting the mash (medium) with ≥30% (wt/vol) dissolved solids at a pH of 5.0 to 5.5 will minimize the effects of bacterial contamination and maximize ethanol production by yeast. PMID:15870306

Use of corn steep liquor as an economical nitrogen source for biosuccinic acid production by Actinobacillus succinogenes

NASA Astrophysics Data System (ADS)

Tan, J. P.; Jahim, J. M.; Wu, T. Y.; Harun, S.; Mumtaz, T.

2016-06-01

Expensive raw materials are the driving force that leads to the shifting of the petroleum-based succinic acid production into bio-based succinic acid production by microorganisms. Cost of fermentation medium is among the main factors contributing to the total production cost of bio-succinic acid. After carbon source, nitrogen source is the second largest component of the fermentation medium, the cost of which has been overlooked for the past years. The current study aimed at replacing yeast extract- a costly nitrogen source with corn steep liquor for economical production of bio-succinic acid by Actinobacillus succinogenes 130Z. In this study, a final succinic acid concentration of 20.6 g/L was obtained from the use of corn steep liquor as the nitrogen source, which was comparable with the use of yeast extract as the nitrogen source that had a final succinate concentration of 21.4 g/l. In terms of economical wise, corn steep liquor was priced at 200 /ton, which was one fifth of the cost of yeast extract at 1000 /ton. Therefore, corn steep liquor can be considered as a potential nitrogen source in biochemical industries instead of the costly yeast extract.

Distribution of dimorphic yeast species in commercial extra virgin olive oil.

PubMed

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

2010-12-01

Recent microbiological research has demonstrated the presence of a rich microflora mainly composed of yeasts in the suspended fraction of freshly produced olive oil. Some of the yeasts are considered useful as they improve the organoleptic characteristics of the oil during preservation, whereas others are considered harmful as they can damage the quality of the oil through the hydrolysis of the triglycerides. However, some dimorphic species can also be found among the unwanted yeasts present in the oil, considered to be opportunistic pathogens to man as they have often been isolated from immunocompromised hospital patients. Present research demonstrates the presence of dimorphic yeast forms in 26% of the commercial extra virgin olive oil originating from different geographical areas, where the dimorphic yeasts are represented by 3-99.5% of the total yeasts. The classified isolates belonged to the opportunistic pathogen species Candida parapsilosis and Candida guilliermondii, while among the dimorphic yeasts considered not pathogenic to man, the Candida diddensiae species was highlighted for the first time in olive oil. The majority of the studied yeast strains resulted lipase positive, and can consequently negatively influence the oil quality through the hydrolysis of the triglycerides. Furthermore, all the strains showed a high level of affinity with some organic solvents and a differing production of biofilm in "vitro" corresponded to a greater or lesser hydrophobia of their cells. Laboratory trials indicated that the dimorphic yeasts studied are sensitive towards some components of the oil among which oleic acid, linoleic acid and triolein, whereas a less inhibiting effect was observed with tricaprilin or when the total polyphenols extracted from the oil were used. The observations carried out on a scanning electron microscope (SEM), demonstrated the production of long un-branched pseudohyphae in all the tested dimorphic yeasts when cultivated on nutrient

Strain and culture medium optimization for production enhancement of prodiginines from marine-derived Streptomyces sp. GQQ-10

NASA Astrophysics Data System (ADS)

Li, Xueping; Zhang, Guojian; Zhu, Tianjiao; Li, Dehai; Gu, Qianqun

2012-09-01

A mutant (GQQ-M6) of a Sponge-Derived streptomyces sp. GQQ-10 obtained by UV-induced mutation was used for producing prodiginines (PGs). Single factor experiments and orthogonal array design (OAD) methods were employed for medium optimization. In the single factor method, the effects of soluble starch, glucose, soybean flour, yeast extract and sodium acetate on PGs production were investigated individually. In the subsequent OAD experiments, the concentrations of these 5 key nutritional components combined with salinity were further adjusted. The mutant strain GQQ-M6 gave a 2.2-fold higher PGs production than that of the parent strain; OAD experiments offered a PGs yield of 61mg L-1, which was 10 times higher than that of the initial GQQ-10 strain under the original cultivation mode.

Application of proanthocyanidins from peanut skins as a natural yeast inhibitory agent.

PubMed

Sarnoski, Paul J; Boyer, Renee R; O'Keefe, Sean F

2012-04-01

Proanthocyanidins were extracted from peanut skins and investigated for their antimicrobial activity against Saccharomyces cerevisiae, Zygosaccharomyces bailii, and Zygosaccharomyces bisporus in traditional growth media (Sabouraud Dextrose and Maltose broth) and a simulated apple juice beverage. Peanut skins extracts (PSE) were prepared through a multisolvent extraction procedure. The PSE extended the lag phase growth of the 3 yeasts studied at a concentration of 1 mg/mL and at 10 mg/mL yeast growth was totally inhibited for 120 h. PSE was fractionated by normal phase high performance liquid chromatography and the active components/fractions were determined. Compounds present in the fractions were identified by liquid chromatography-mass spectrometry to determine the compounds responsible for inhibition. Fractions consisting mostly of A-type proanthocyanidin dimers, trimers, and tetramers showed the highest percent inhibition toward the yeasts tested in this study. Both optical density (OD) and standard enumeration plating methods were performed in this study. The OD method led to an overestimation of the inhibitory effects of PSE, the 2 methods agreed in respect to treatment effects but not the severity of the inhibition. There is a growing consumer demand for "fresh like" products containing reduced amounts of chemical preservatives without compromising food safety and quality. Therefore, the goal of this study was to determine if an extract of peanut skins containing flavonoid rich compounds could function as a natural antimicrobial in a model beverage system. Proteins were removed through the process of producing the peanut skin extract, thus it is unlikely to contain peanut allergens. The antimicrobial compounds mentioned in this study were successfully integrated into a model beverage system, and were found to have antimicrobial effect. However, the incorporation of these compounds would likely lead to negative sensory attributes at the concentration needed

The protective effects of Rhodiola crenulata extracts on Drosophila melanogaster gut immunity induced by bacteria and SDS toxicity.

PubMed

Zhu, Caixia; Guan, Fachun; Wang, Chao; Jin, Li Hua

2014-12-01

The aim of this study was to observe the effect of the Rhodiola crenulata extracts on gut immunity of Drosophila melanogaster. Wild-type flies fed standard cornmeal-yeast medium were used as controls. Experimental groups were supplemented with 2.5% R. crenulata aqueous extracts in standard medium. Survival rate was determined by feeding pathogenic microorganisms and toxic compounds. The levels of reactive oxygen species and dead cells were detected by dihydroethidium and 7-amino-actinomycin D staining, respectively. The expression of antimicrobial peptides was evaluated by quantitative polymerase chain reaction, and morphological change of the intestine was imaged by an Axioskop 2 plus microscope. The results demonstrate that R. crenulata increased the survival rates of adult flies and expression of antimicrobial peptide genes after pathogen or toxic compound ingestion. Moreover, decreased levels of reactive oxygen species and epithelial cell death were associated with results in improved intestinal morphology. The pharmacological action of R. crenulata from Tibet was greater than that from Sichuan. These results indicate that the R. crenulata extracts from Tibet had better pharmacological effect on D. melanogaster gut immunity after ingestion of pathogens and toxic compounds. These results may provide the pharmacological basis for prevention of inflammatory diseases of the intestine. Copyright © 2014 John Wiley & Sons, Ltd.

Exogenous calcium improves viability of biocontrol yeasts under heat stress by reducing ROS accumulation and oxidative damage of cellular protein.

PubMed

An, Bang; Li, Boqiang; Qin, Guozheng; Tian, Shiping

2012-08-01

In this article, we investigated the effect of exogenous calcium on improving viability of Debaryomyces hansenii and Pichia membranaefaciens under heat stress, and evaluated the role of calcium in reducing oxidant damage of proteins in the yeast cells. The results indicated that high concentration of exogenous calcium in culture medium was beneficial for enhancing the tolerance of the biocontrol yeasts to heat stress. The possible mechanism of calcium improving the viability of yeasts was attributed to enhancement of antioxidant enzyme activities, decrease in ROS accumulation and reduction of oxidative damage of intracellular protein in yeast cells under heat stress. D. hansenii is more sensitive to calcium as compared to P. membranaefaciens. Our results suggest that application of exogenous calcium combined with biocontrol yeasts is a practical approach for the control of postharvest disease in fruit.

Engineering yeast metabolism for production of terpenoids for use as perfume ingredients, pharmaceuticals and biofuels.

PubMed

Zhang, Yueping; Nielsen, Jens; Liu, Zihe

2017-12-01

Terpenoids represent a large class of natural products with significant commercial applications. These chemicals are currently mainly obtained through extraction from plants and microbes or through chemical synthesis. However, these sources often face challenges of unsustainability and low productivity. In order to address these issues, Escherichia coli and yeast have been metabolic engineered to produce non-native terpenoids. With recent reports of engineering yeast metabolism to produce several terpenoids at high yields, it has become possible to establish commercial yeast production of terpenoids that find applications as perfume ingredients, pharmaceuticals and advanced biofuels. In this review, we describe the strategies to rewire the yeast pathway for terpenoid biosynthesis. Recent advances will be discussed together with challenges and perspectives of yeast as a cell factory to produce different terpenoids. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Nitrogen recycling from fuel-extracted algal biomass: residuals as the sole nitrogen source for culturing Scenedesmus acutus.

PubMed

Gu, Huiya; Nagle, Nick; Pienkos, Philip T; Posewitz, Matthew C

2015-05-01

In this study, the reuse of nitrogen from fuel-extracted algal residues was investigated. The alga Scenedesmus acutus was found to be able to assimilate nitrogen contained in amino acids, yeast extracts, and proteinaceous alga residuals. Moreover, these alternative nitrogen resources could replace nitrate in culturing media. The ability of S. acutus to utilize the nitrogen remaining in processed algal biomass was unique among the promising biofuel strains tested. This alga was leveraged in a recycling approach where nitrogen is recovered from algal biomass residuals that remain after lipids are extracted and carbohydrates are fermented to ethanol. The protein-rich residuals not only provided an effective nitrogen resource, but also contributed to a carbon "heterotrophic boost" in subsequent culturing, improving overall biomass and lipid yields relative to the control medium with only nitrate. Prior treatment of the algal residues with Diaion HP20 resin was required to remove compounds inhibitory to algal growth. Copyright © 2014 Elsevier Ltd. All rights reserved.

Extracting nuclear sizes of medium to heavy nuclei from total reaction cross sections

NASA Astrophysics Data System (ADS)

Horiuchi, W.; Hatakeyama, S.; Ebata, S.; Suzuki, Y.

2016-04-01

Background: Proton and neutron radii are fundamental quantities of atomic nuclei. To study the sizes of short-lived unstable nuclei, there is a need for an alternative to electron scattering. Purpose: The recent paper by Horiuchi et al. [Phys. Rev. C 89, 011601(R) (2014)], 10.1103/PhysRevC.89.011601 proposed a possible way of extracting the matter and neutron-skin thickness of light- to medium-mass nuclei using total reaction cross section, σR. The analysis is extended to medium to heavy nuclei up to lead isotopes with due attention to Coulomb breakup contributions as well as density distributions improved by paring correlation. Methods: We formulate a quantitative calculation of σR based on the Glauber model including the Coulomb breakup. To substantiate the treatment of the Coulomb breakup, we also evaluate the Coulomb breakup cross section due to the electric dipole field in a canonical-basis-time-dependent-Hartree-Fock-Bogoliubov theory in the three-dimensional coordinate space. Results: We analyze σR's of 103 nuclei with Z =20 , 28, 40, 50, 70, and 82 incident on light targets, H,21, 4He, and 12C. Three kinds of Skyrme interactions are tested to generate those wave functions. To discuss possible uncertainty due to the Coulomb breakup, we examine its dependence on the target, the incident energy, and the Skyrme interaction. The proton is a most promising target for extracting the nuclear sizes as the Coulomb excitation can safely be neglected. We find that the so-called reaction radius, aR=√{σR/π } , for the proton target is very well approximated by a linear function of two variables, the matter radius and the skin thickness, in which three constants depend only on the incident energy. We quantify the accuracy of σR measurements needed to extract the nuclear sizes. Conclusions: The proton is the best target because, once the incident energy is set, its aR is very accurately determined by only the matter radius and neutron-skin thickness. If σR's at

Could yeast infections impair recovery from mental illness? A case study using micronutrients and olive leaf extract for the treatment of ADHD and depression.

PubMed

Rucklidge, Julia J

2013-01-01

Micronutrients are increasingly used to treat psychiatric disorders including attention-deficit/hyperactivity disorder (ADHD), mood disorders, stress, and anxiety. However, a number of factors influence optimal response and absorption of nutrients, including the health of the gut, particularly the presence of yeast infections, such as Candida. As part of a wider investigation into the impact of micronutrients on psychiatric symptoms, many participants who experienced a yeast infection during their treatment showed a diminished response to the micronutrients. One case was followed systematically over a period of 3 y with documentation of deterioration in psychiatric symptoms (ADHD and mood) when infected with Candida and then symptom improvement following successful treatment of the infection with olive leaf extract (OLE) and probiotics. This case outlines that micronutrient treatment might be severely compromised by infections such as Candida and may highlight the importance of gut health when treating psychiatric disorders with nutrients. Given the role that inflammation can play in absorption of nutrients, it was hypothesized that the infection was impairing absorption of the micronutrients.

In Vitro Anti-Malassezia Activity of Castanea crenata Shell and Oil-Soluble Glycyrrhiza Extracts

PubMed Central

Han, Song Hee; Hur, Min Seok; Kim, Min Jung; Jung, Won Hee; Park, Minji; Kim, Jeong Hwan; Shin, Hong Ju; Choe, Yong Beom; Ahn, Kyu Joong

2017-01-01

Background A new shampoo with anti-Malassezia properties obtained from various plants is required to provide seborrheic dermatitis patients with a wider range of treatment options. Objective The aim of this study was to obtain in vitro susceptibility profiles of Malassezia restricta and M. globosa, the most important pathogenic organisms in the development of seborrheic dermatitis, to the plant extracts used in commercial anti-dandruff shampoos. Methods Minimal inhibitory concentrations (MICs) were determined for eight candidate plant extracts and two plant-derived natural products diluted with Leeming and Notman medium to final concentrations of 0.016 to 1 mg/ml. Results Castanea crenata shell, Camellia sinensis leaf, and oil-soluble Glycyrrhiza extracts presented relatively low MIC values (≤0.5 mg/ml) against both strains. The C. crenata shell and oil-soluble Glycyrrhiza extracts demonstrated especially high anti-Malassezia activity, suggesting their potential use in the treatment of seborrheic dermatitis. The extracts also showed fungistatic activity against other common facultative pathogenic yeasts, Cryptococcus and Candida. Conclusion C. crenata shell and oil-soluble Glycyrrhiza extracts could potentially be used as active ingredients in anti-seborrheic and anti-dandruff shampoo formulations. They could be helpful for repeated treatments and regular prophylaxis of scalp seborrheic dermatitis. PMID:28566909

Spectrophotometric evaluation of selenium binding by Saccharomyces cerevisiae ATCC MYA-2200 and Candida utilis ATCC 9950 yeast.

PubMed

Kieliszek, Marek; Błażejak, Stanisław; Płaczek, Maciej

2016-05-01

In this study, the ability of selenium binding the biomas of Saccharomyces cerevisiae ATCC MYA-2200 and Candida utilis ATCC 9950 was investigated. Sodium selenite(IV) salts were added to the experimental media at concentrations of 10, 20, 40, and 60 mg Se(4+) L(-1). In the tested concentration range, one concentration reported a significant reduction in the biomass yield of both yeast strains. Intense growth was observed for C. utilis yeast, which reached the highest biomass yield of 15 gd.w.L(-1) after 24h cultivation in the presence of 10mg Se(4+) L(-1). Based on the use of spectrophotometric method for the determination of selenium content by using Variamine Blue as a chromogenic agent, efficient accumulation of this element in the biomass of the investigated yeast was observed. The highest amount of selenium, that is, 5.64 mg Se(4+)gd.w.(-1), was bound from the environment by S. cerevisiae ATCC MYA-2200 cultured in the presence of 60 mg Se(4+) L(-1) medium 72h Slightly less amount, 5.47 mg Se(4+) gd.w.(-1), was absorbed by C. utilis ATCC 9950 during similar cultural conditions. Based on the results of the biomass yield and the use of selenium from the medium, it can be observed that yeasts of the genus Candida are more efficient in binding this element, and this property finds practical application in the production of selenium-enriched yeast. Copyright © 2016 Elsevier GmbH. All rights reserved.

Synthesis of yeast extract-stabilized Cu nanoclusters for sensitive fluorescent detection of sulfide ions in water.

PubMed

Jin, Lihua; Zhang, Zaihua; Tang, Anwen; Li, Cong; Shen, Yehua

2016-05-15

In this work, we have presented a novel strategy to utilize as-synthesized yeast extract-stabilized Cu nanoclusters (Cu NCs) for sensitive and selective detection of S(2-). The fluorescence intensity of Cu NCs was enhanced significantly in the presence of both Na2S2O8 and S(2-). By virtue of this specific response, a Cu NC-based fluorescent turn-on sensor was developed, which allows the detection of S(2-) in the range of 0.02-0.8 μM with a detection limit of 10nM. The enhancing mechanism was also discussed based on fluorescence decay, transmission electron microscopy (TEM) and dynamic light scattering (DLS) studies, indicating that S(2-) enhanced the Cu NCs emission mainly through sulfide-induced aggregation of Cu NCs. Furthermore, we demonstrated the usability of the present approach for the detection of S(2-) in water samples, which illustrates its great potential for the environmental monitoring and water quality inspection fields. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of the Microbial Identification System for identification of clinically isolated yeasts.

PubMed Central

Crist, A E; Johnson, L M; Burke, P J

1996-01-01

The Microbial Identification System (MIS; Microbial ID, Inc., Newark, Del.) was evaluated for the identification of 550 clinically isolated yeasts. The organisms evaluated were fresh clinical isolates identified by methods routinely used in our laboratory (API 20C and conventional methods) and included Candida albicans (n = 294), C. glabrata (n = 145), C. tropicalis (n = 58), C. parapsilosis (n = 33), and other yeasts (n = 20). In preparation for fatty acid analysis, yeasts were inoculated onto Sabouraud dextrose agar and incubated at 28 degrees C for 24 h. Yeasts were harvested, saponified, derivatized, and extracted, and fatty acid analysis was performed according to the manufacturer's instructions. Fatty acid profiles were analyzed, and computer identifications were made with the Yeast Clinical Library (database version 3.8). Of the 550 isolates tested, 374 (68.0%) were correctly identified to the species level, with 87 (15.8%) being incorrectly identified and 89 (16.2%) giving no identification. Repeat testing of isolates giving no identification resulted in an additional 18 isolates being correctly identified. This gave the MIS an overall identification rate of 71.3%. The most frequently misidentified yeast was C. glabrata, which was identified as Saccharomyces cerevisiae 32.4% of the time. On the basis of these results, the MIS, with its current database, does not appear suitable for the routine identification of clinically important yeasts. PMID:8880489

Metabolic regulation of yeast

NASA Astrophysics Data System (ADS)

Fiechter, A.

1982-12-01

Metabolic regulation which is based on endogeneous and exogeneous process variables which may act constantly or time dependently on the living cell is discussed. The observed phenomena of the regulation are the result of physical, chemical, and biological parameters. These parameters are identified. Ethanol is accumulated as an intermediate product and the synthesis of biomass is reduced. This regulatory effect of glucose is used for the aerobic production of ethanol. Very high production rates are thereby obtained. Understanding of the regulation mechanism of the glucose effect has improved. In addition to catabolite repression, several other mechanisms of enzyme regulation have been described, that are mostly governed by exogeneous factors. Glucose also affects the control of respiration in a third class of yeasts which are unable to make use of ethanol as a substrate for growth. This is due to the lack of any anaplerotic activity. As a consequence, diauxic growth behavior is reduced to a one-stage growth with a drastically reduced cell yield. The pulse chemostat technique, a systematic approach for medium design is developed and medium supplements that are essential for metabolic control are identified.

Boosting accumulation of neutral lipids in Rhodosporidium kratochvilovae HIMPA1 grown on hemp (Cannabis sativa Linn) seed aqueous extract as feedstock for biodiesel production.

PubMed

Patel, Alok; Pravez, Mohammad; Deeba, Farha; Pruthi, Vikas; Singh, Rajesh P; Pruthi, Parul A

2014-08-01

Hemp seeds aqueous extract (HSAE) was used as cheap renewable feedstocks to grow novel oleaginous yeast Rhodosporidium kratochvilovae HIMPA1 isolated from Himalayan permafrost soil. The yeast showed boosted triglyceride (TAG) accumulation in the lipid droplets (LDs) which were transesterified to biodiesel. The sonicated HSAE prepared lacked toxic inhibitors and showed enhanced total lipid content and lipid yield 55.56%, 8.39±0.57g/l in comparison to 41.92%, 6.2±0.8g/l from industrially used glucose synthetic medium, respectively. Supersized LDs (5.95±1.02μm) accumulated maximum TAG in sonicated HSAE grown cells were visualized by fluorescent BODIPY (505/515nm) stain. GC-MS analysis revealed unique longer carbon chain FAME profile containing Arachidic acid (C20:0) 5%, Behenic acid (C22:0) 9.7%, Heptacosanoic acid (C27:0) 14.98%, for the first time in this yeast when grown on industrially competent sonicated HSAE, showing more similarity to algal oils. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

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

PubMed

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

2018-01-01

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

Identification and characterization of lactic acid bacteria and yeasts of PDO Tuscan bread sourdough by culture dependent and independent methods.

PubMed

Palla, Michela; Cristani, Caterina; Giovannetti, Manuela; Agnolucci, Monica

2017-06-05

Sourdough fermentation has been increasingly used worldwide, in accordance with the demand of consumers for tasty, natural and healthy food. The high diversity of lactic acid bacteria (LAB) and yeast species, detected in sourdoughs all over the world, may affect nutritional, organoleptic and technological traits of leavened baked goods. A wide regional variety of traditional sourdough breads, over 200 types, has been recorded in Italy, including special types selected as worthy of either Protected Geographical Indication (PGI) or Protected Designation of Origin (PDO), whose sourdough microbiota has been functionally and molecularly characterized. As, due to the very recent designation, the microbiota of Tuscan bread sourdough has not been investigated so far, the aim of the present work was to isolate and characterize the species composition of LAB and yeasts of PDO Tuscan bread sourdough by culture-independent and dependent methods. A total of 130 yeasts from WLN medium and 193 LAB from both mMRS and SDB media were isolated and maintained to constitute the germplasm bank of PDO Tuscan bread. Ninety six LAB from mMRS medium and 68 yeasts from WLN medium were randomly selected and molecularly identified by ARDRA (Amplified Ribosomal DNA Restriction Analysis) and PCR-RFLP analysis of the ITS region, respectively, and sequencing. The yeast identity was confirmed by 26S D1/D2 sequencing. All bacterial isolates showed 99% identity with Lactobacillus sanfranciscensis, 65 yeast isolates were identified as Candida milleri, and 3 as Saccharomyces cerevisiae. Molecular characterization of PDO Tuscan bread sourdough by PCR-DGGE confirmed such data. The distinctive tripartite species association, detected as the microbiota characterizing the sourdough used to produce PDO Tuscan bread, encompassed a large number of L. sanfranciscensis and C. milleri strains, along with a few of S. cerevisiae. The relative composition and specific physiological characteristics of such microbiota

Biodegradation of lindane using a novel yeast strain, Rhodotorula sp. VITJzN03 isolated from agricultural soil.

PubMed

Abdul Salam, Jaseetha; Lakshmi, V; Das, Devlina; Das, Nilanjana

2013-03-01

Lindane is a notorious organochlorine pesticide due to its high toxicity, persistence in the environment and its tendency to bioaccumulate. A yeast strain isolated from sorghum cultivation field was able to use lindane as carbon and energy source under aerobic conditions. With molecular techniques, it was identified and named as Rhodotorula strain VITJzN03. The effects of nutritional and environmental factors on yeast growth and the biodegradation of lindane was investigated. The maximum production of yeast biomass along with 100 % lindane mineralization was noted at an initial lindane concentration of 600 mg l(-1) within a period of 10 days. Lindane concentration above 600 mg l(-1) inhibited the growth of yeast in liquid medium. A positive relationship was noted between the release of chloride ions and the increase of yeast biomass as well as degradation of lindane. The calculated degradation rate and half life of lindane were found to be 0.416 day(-1) and 1.66 days, respectively. The analysis of the metabolites using GC-MS identified the formation of seven intermediates including γ-pentachlorocyclohexane(γ-PCCH), 1,3,4,6-tetrachloro-1,4-cyclohexadiene(1,4-TCCHdiene), 1,2,4-trichlorobenzene (1,2,4 TCB), 1,4-dichlorobenzene (1,4 DCB), chloro-cis-1,2-dihydroxycyclohexadiene (CDCHdiene), 3-chlorocatechol (3-CC) and maleylacetate (MA) derivatives indicating that lindane degradation follows successive dechlorination and oxido-reduction. Based on the results of the present study, the possible pathway for lindane degradation by Rhodotorula sp. VITJzN03 has been proposed. To the best of our knowledge, this is the first report on lindane degradation by yeast which can serve as a potential agent for in situ bioremediation of medium to high level lindane-contaminated sites.

Immobilised Sarawak Malaysia yeast cells for production of bioethanol.

PubMed

Zain, Masniroszaime Mohd; Kofli, Noorhisham Tan; Rozaimah, Siti; Abdullah, Sheikh

2011-05-01

Bioethanol production using yeast has become a popular topic due to worrying depleting worldwide fuel reserve. The aim of the study was to investigate the capability of Malaysia yeast strains isolated from starter culture used in traditional fermented food and alcoholic beverages in producing Bioethanol using alginate beads entrapment method. The starter yeast consists of groups of microbes, thus the yeasts were grown in Sabouraud agar to obtain single colony called ST1 (tuak) and ST3 (tapai). The growth in Yeast Potatoes Dextrose (YPD) resulted in specific growth of ST1 at micro = 0.396 h-1 and ST3 at micro = 0.38 h-1, with maximum ethanol production of 7.36 g L-1 observed using ST1 strain. The two strains were then immobilized using calcium alginate entrapment method producing average alginate beads size of 0.51 cm and were grown in different substrates; YPD medium and Local Brown Sugar (LBS) for 8 h in flask. The maximum ethanol concentration measured after 7 h were at 6.63 and 6.59 g L-1 in YPD media and 1.54 and 1.39 g L-1in LBS media for ST1 and ST3, respectively. The use of LBS as carbon source showed higher yield of product (Yp/s), 0.59 g g-1 compared to YPD, 0.25 g g-1 in ST1 and (Yp/s), 0.54 g g-1 compared to YPD, 0.24 g g-1 in ST3 . This study indicated the possibility of using local strains (STI and ST3) to produce bioethanol via immobilization technique with local materials as substrate.

[Inhibitory effects of butyl alcohol extract of Baitouweng decoction on yeast-to-hyphae transition of Candida albicans isolates from VVC in alkaline pH environment].

PubMed

Zhang, Meng-xiang; Xia, Dan; Shi, Gao-xiang; Shao, Jing; Wang, Tian-ming; Tang, Chuan-chao; Wang, Chang-zhong

2015-02-01

To investigate the effects of butyl alcohol extract of Baitouweng decoction ( BAEB) on yeast-to-hyphae transition of Candida albicans isolates from vulvovaginal candidiasis (VVC) in alkaline pH. Serial 2-fold dilution assay was used to determine the minimal inhibitory concentrations (MICs) of Baitouweng decoction extracts against C. albicans isolates from VVC, XTT assay was applied to determine the metabolic activity of C. albicans hypha treated by BAEB for 6 h. The morphological change of C. albicans treated by BAEB was inspected at different pH by inverted microscope, fluorescence microscope, scanning electron microscopy (SEM). Solid agar plate and semi-solid agar were utilized to evaluate colony morphology and invasive growth of C. albicans, respectively. Quantitative Real-time PCR (qRT-PCR) was adopted to observe the expressions of hyphae-specific genes including HWP1, ALS3, CSH1, SUN41 and CaPDE2. The MIC of BAEB against C. albicans is less than that of other extracts; hyphae grow best at pH 8. 0; 512 mg · L(-1) and 1,024 mg · L(-1) BAEB could inhibit formation of hyphae and influence colony morphology. When treated by 512 mg · L(-1) and 1,024 mg · L(-1) BAEB, the colonies became smooth; while by 0 and 256 mg · L(-1) BAEB, the colonies became wrinkled. In semi-solid agar, the length of hyphae decreased steadily as the concentration of BAEB lowered. The expression of HWP1, ALS3, CSHl, SUN41 were downregulated by 5.12, 4.26, 3.2 and 2.74 folds, and CaPDE2 was upregulated by 2.38 fold. BAEB could inhibit yeast-to-hyphae transition of C. albicans isolates from VVC in alkaline pH.

Yeast synthetic biology for high-value metabolites.

PubMed

Dai, Zhubo; Liu, Yi; Guo, Juan; Huang, Luqi; Zhang, Xueli

2015-02-01

Traditionally, high-value metabolites have been produced through direct extraction from natural biological sources which are inefficient, given the low abundance of these compounds. On the other hand, these high-value metabolites are usually difficult to be synthesized chemically, due to their complex structures. In the last few years, the discovery of genes involved in the synthetic pathways of these metabolites, combined with advances in synthetic biology tools, has allowed the construction of increasing numbers of yeast cell factories for production of these metabolites from renewable biomass. This review summarizes recent advances in synthetic biology in terms of the use of yeasts as microbial hosts for the identification of the pathways involved in the synthesis, as well as for the production of high-value metabolites. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

Drosophila Regulate Yeast Density and Increase Yeast Community Similarity in a Natural Substrate

PubMed Central

Stamps, Judy A.; Yang, Louie H.; Morales, Vanessa M.; Boundy-Mills, Kyria L.

2012-01-01

Drosophila melanogaster adults and larvae, but especially larvae, had profound effects on the densities and community structure of yeasts that developed in banana fruits. Pieces of fruit exposed to adult female flies previously fed fly-conditioned bananas developed higher yeast densities than pieces of the same fruits that were not exposed to flies, supporting previous suggestions that adult Drosophila vector yeasts to new substrates. However, larvae alone had dramatic effects on yeast density and species composition. When yeast densities were compared in pieces of the same fruits assigned to different treatments, fruits that developed low yeast densities in the absence of flies developed significantly higher yeast densities when exposed to larvae. Across all of the fruits, larvae regulated yeast densities within narrow limits, as compared to a much wider range of yeast densities that developed in pieces of the same fruits not exposed to flies. Larvae also affected yeast species composition, dramatically reducing species diversity across fruits, reducing variation in yeast communities from one fruit to the next (beta diversity), and encouraging the consistent development of a yeast community composed of three species of yeast (Candida californica, C. zemplinina, and Pichia kluvyeri), all of which were palatable to larvae. Larvae excreted viable cells of these three yeast species in their fecal pools, and discouraged the growth of filamentous fungi, processes which may have contributed to their effects on the yeast communities in banana fruits. These and other findings suggest that D. melanogaster adults and their larval offspring together engage in ‘niche construction’, facilitating a predictable microbial environment in the fruit substrates in which the larvae live and develop. PMID:22860093

Isolation and Characterization of Brewer's Yeast Variants with Improved Fermentation Performance under High-Gravity Conditions▿

PubMed Central

Blieck, Lies; Toye, Geert; Dumortier, Françoise; Verstrepen, Kevin J.; Delvaux, Freddy R.; Thevelein, Johan M.; Van Dijck, Patrick

2007-01-01

To save energy, space, and time, today's breweries make use of high-gravity brewing in which concentrated medium (wort) is fermented, resulting in a product with higher ethanol content. After fermentation, the product is diluted to obtain beer with the desired alcohol content. While economically desirable, the use of wort with an even higher sugar concentration is limited by the inability of brewer's yeast (Saccharomyces pastorianus) to efficiently ferment such concentrated medium. Here, we describe a successful strategy to obtain yeast variants with significantly improved fermentation capacity under high-gravity conditions. We isolated better-performing variants of the industrial lager strain CMBS33 by subjecting a pool of UV-induced variants to consecutive rounds of fermentation in very-high-gravity wort (>22° Plato). Two variants (GT336 and GT344) showing faster fermentation rates and/or more-complete attenuation as well as improved viability under high ethanol conditions were identified. The variants displayed the same advantages in a pilot-scale stirred fermenter under high-gravity conditions at 11°C. Microarray analysis identified several genes whose altered expression may be responsible for the superior performance of the variants. The role of some of these candidate genes was confirmed by genetic transformation. Our study shows that proper selection conditions allow the isolation of variants of commercial brewer's yeast with superior fermentation characteristics. Moreover, it is the first study to identify genes that affect fermentation performance under high-gravity conditions. The results are of interest to the beer and bioethanol industries, where the use of more-concentrated medium is economically advantageous. PMID:17158628

Effects of temperature and medium composition on inhibitory activities of gossypol-related compounds against aflatoxigenic fungi.

PubMed

Mellon, J E; Dowd, M K; Beltz, S B

2013-07-01

To investigate the effects of temperature and medium composition on growth/aflatoxin inhibitory activities of terpenoids gossypol, gossypolone and apogossypolone against Aspergillus flavus and A. parasiticus. The compounds were tested at a concentration of 100 μg ml(-1) in a Czapek Dox (Czapek) agar medium at 25, 31 and 37°C. Increased incubation temperature marginally increased growth inhibition caused by these compounds, but reduced the aflatoxin inhibition effected by gossypol. Gossypolone and apogossypolone retained good aflatoxin inhibitory activity against A. flavus and A. parasiticus at higher incubation temperatures. However, increased temperature also significantly reduced aflatoxin production in control cultures. The effects of the terpenoids on fungal growth and aflatoxin production against the same fungi were also determined in Czapek, Czapek with a protein/amino acid addendum and yeast extract sucrose (YES) media. Growth of these fungi in the protein-supplemented Czapek medium or in the YES medium greatly reduced the growth inhibition effects of the terpenoids. Apogossypolone displayed strong anti-aflatoxigenic activity in the Czapek medium, but this activity was significantly reduced in the protein-amended Czapek and YES media. Gossypol, which displayed little to no aflatoxin inhibitory activity in the Czapek medium, did yield significant anti-aflatoxigenic activity in the YES medium. Incubation temperature and media composition are important parameters involved in the regulation of aflatoxin production in A. flavus and A. parasiticus. These parameters also affect the potency of growth and aflatoxin inhibitory activities of these gossypol-related compounds against aflatoxigenic fungi. Studies utilizing gossypol-related compounds as inhibitory agents of biological activities should be interpreted with caution due to compound interaction with multiple components of the test system, especially serum proteins. Published [2013]. This article is a

Primary Metabolism and Medium-Chain Fatty Acid Alterations Precede Long-Chain Fatty Acid Changes Impacting Neutral Lipid Metabolism in Response to an Anticancer Lysophosphatidylcholine Analogue in Yeast.

PubMed

Tambellini, Nicolas P; Zaremberg, Vanina; Krishnaiah, Saikumari; Turner, Raymond J; Weljie, Aalim M

2017-10-06

The nonmetabolizable lysophosphatidylcholine (LysoPC) analogue edelfosine is the prototype of a class of compounds being investigated for their potential as selective chemotherapeutic agents. Edelfosine targets membranes, disturbing cellular homeostasis. Is not clear at this point how membrane alterations are communicated between intracellular compartments leading to growth inhibition and eventual cell death. In the present study, a combined metabolomics/lipidomics approach for the unbiased identification of metabolic pathways altered in yeast treated with sublethal concentrations of the LysoPC analogue was employed. Mass spectrometry of polar metabolites, fatty acids, and lipidomic profiling was used to study the effects of edelfosine on yeast metabolism. Amino acid and sugar metabolism, the Krebs cycle, and fatty acid profiles were most disrupted, with polar metabolites and short-medium chain fatty acid changes preceding long and very long-chain fatty acid variations. Initial increases in metabolites such as trehalose, proline, and γ-amino butyric acid with a concomitant decrease in metabolites of the Krebs cycle, citrate and fumarate, are interpreted as a cellular attempt to offset oxidative stress in response to mitochondrial dysfunction induced by the treatment. Notably, alanine, inositol, and myristoleic acid showed a steady increase during the period analyzed (2, 4, and 6 h after treatment). Of importance was the finding that edelfosine induced significant alterations in neutral glycerolipid metabolism resulting in a significant increase in the signaling lipid diacylglycerol.

Fermentation behaviour and volatile compound production by agave and grape must yeasts in high sugar Agave tequilana and grape must fermentations.

PubMed

Arrizon, Javier; Fiore, Concetta; Acosta, Guillermina; Romano, Patrizia; Gschaedler, Anne

2006-01-01

Few studies have been performed on the characterization of yeasts involved in the production of agave distilled beverages and their individual fermentation properties. In this study, a comparison and evaluation of yeasts of different origins in the tequila and wine industries were carried out for technological traits. Fermentations were carried out in high (300 g l(-1)) and low (30 g l(-1)) sugar concentrations of Agave tequilana juice, in musts obtained from Fiano (white) and Aglianico (red) grapes and in YPD medium (with 270 g l(-1) of glucose added) as a control. Grape yeasts exhibited a reduced performance in high-sugar agave fermentation, while both agave and grape yeasts showed similar fermentation behaviour in grape musts. Production levels of volatile compounds by grape and agave yeasts differed in both fermentations.

Defective quiescence entry promotes the fermentation performance of bottom-fermenting brewer's yeast.

PubMed

Oomuro, Mayu; Kato, Taku; Zhou, Yan; Watanabe, Daisuke; Motoyama, Yasuo; Yamagishi, Hiromi; Akao, Takeshi; Aizawa, Masayuki

2016-11-01

One of the key processes in making beer is fermentation. In the fermentation process, brewer's yeast plays an essential role in both the production of ethanol and the flavor profile of beer. Therefore, the mechanism of ethanol fermentation by of brewer's yeast is attracting much attention. The high ethanol productivity of sake yeast has provided a good basis from which to investigate the factors that regulate the fermentation rates of brewer's yeast. Recent studies found that the elevated fermentation rate of sake Saccharomyces cerevisiae species is closely related to a defective transition from vegetative growth to the quiescent (G 0 ) state. In the present study, to clarify the relationship between the fermentation rate of brewer's yeast and entry into G 0 , we constructed two types of mutant of the bottom-fermenting brewer's yeast Saccharomyces pastorianus Weihenstephan 34/70: a RIM15 gene disruptant that was defective in entry into G 0 ; and a CLN3ΔPEST mutant, in which the G 1 cyclin Cln3p accumulated at high levels. Both strains exhibited higher fermentation rates under high-maltose medium or high-gravity wort conditions (20° Plato) as compared with the wild-type strain. Furthermore, G 1 arrest and/or G 0 entry were defective in both the RIM15 disruptant and the CLN3ΔPEST mutant as compared with the wild-type strain. Taken together, these results indicate that regulation of the G 0 /G 1 transition might govern the fermentation rate of bottom-fermenting brewer's yeast in high-gravity wort. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Statistical optimization of medium components and growth conditions by response surface methodology to enhance phenol degradation by Pseudomonas putida.

PubMed

Annadurai, Gurusamy; Ling, Lai Yi; Lee, Jiunn-Fwu

2008-02-28

In this work, a four-level Box-Behnken factorial design was employed combining with response surface methodology (RSM) to optimize the medium composition for the degradation of phenol by pseudomonas putida (ATCC 31800). A mathematical model was then developed to show the effect of each medium composition and their interactions on the biodegradation of phenol. Response surface method was using four levels like glucose, yeast extract, ammonium sulfate and sodium chloride, which also enabled the identification of significant effects of interactions for the batch studies. The biodegradation of phenol on Pseudomonas putida (ATCC 31800) was determined to be pH-dependent and the maximum degradation capacity of microorganism at 30 degrees C when the phenol concentration was 0.2 g/L and the pH of the solution was 7.0. Second order polynomial regression model was used for analysis of the experiment. Cubic and quadratic terms were incorporated into the regression model through variable selection procedures. The experimental values are in good agreement with predicted values and the correlation coefficient was found to be 0.9980.

Identification and characterisation of xylanolytic yeasts isolated from decaying wood and sugarcane bagasse in Brazil.

PubMed

Lara, Carla A; Santos, Renata O; Cadete, Raquel M; Ferreira, Carla; Marques, Susana; Gírio, Francisco; Oliveira, Evelyn S; Rosa, Carlos A; Fonseca, César

2014-06-01

In this study, yeasts associated with lignocellulosic materials in Brazil, including decaying wood and sugarcane bagasse, were isolated, and their ability to produce xylanolytic enzymes was investigated. A total of 358 yeast isolates were obtained, with 198 strains isolated from decaying wood and 160 strains isolated from decaying sugarcane bagasse samples. Seventy-five isolates possessed xylanase activity in solid medium and were identified as belonging to nine species: Candida intermedia, C. tropicalis, Meyerozyma guilliermondii, Scheffersomyces shehatae, Sugiyamaella smithiae, Cryptococcus diffluens, Cr. heveanensis, Cr. laurentii and Trichosporon mycotoxinivorans. Twenty-one isolates were further screened for total xylanase activity in liquid medium with xylan, and five xylanolytic yeasts were selected for further characterization, which included quantitative analysis of growth in xylan and xylose and xylanase and β-D-xylosidase activities. The yeasts showing the highest growth rate and cell density in xylan, Cr. laurentii UFMG-HB-48, Su. smithiae UFMG-HM-80.1 and Sc. shehatae UFMG-HM-9.1a, were, simultaneously, those exhibiting higher xylanase activity. Xylan induced the highest level of (extracellular) xylanase activity in Cr. laurentii UFMG-HB-48 and the highest level of (intracellular, extracellular and membrane-associated) β-D-xylosidase activity in Su. smithiae UFMG-HM-80.1. Also, significant β-D-xylosidase levels were detected in xylan-induced cultures of Cr. laurentii UFMG-HB-48 and Sc. shehatae UFMG-HM-9.1a, mainly in extracellular and intracellular spaces, respectively. Under xylose induction, Cr. laurentii UFMG-HB-48 showed the highest intracellular β-D-xylosidase activity among all the yeast tested. C. tropicalis UFMG-HB 93a showed its higher (intracellular) β-D-xylosidase activity under xylose induction and higher at 30 °C than at 50 °C. This study revealed different xylanolytic abilities and strategies in yeasts to metabolise xylan and

Breeding research on sake yeasts in Japan: history, recent technological advances, and future perspectives.

PubMed

Kitagaki, Hiroshi; Kitamoto, Katsuhiko

2013-01-01

Sake is an alcoholic beverage of Japan, with a tradition lasting more than 1,300 years; it is produced from rice and water by fermenting with the koji mold Aspergillus oryzae and sake yeast Saccharomyces cerevisiae. Breeding research on sake yeasts was originally developed in Japan by incorporating microbiological and genetic research methodologies adopted in other scientific areas. Since the advent of a genetic paradigm, isolation of yeast mutants has been a dominant approach for the breeding of favorable sake yeasts. These sake yeasts include (a) those that do not form foams (produced by isolating a mutant that does not stick to foams, thus decreasing the cost of sake production); (b) those that do not produce urea, which leads to the formation of ethyl carbamate, a possible carcinogen (isolated by positive selection in a canavanine-, arginine-, and ornithine-containing medium); (c) those that produce an increased amount of ethyl caproate, an apple-like flavor (produced by isolating a mutant resistant to cerulenin, an inhibitor of fatty-acid synthesis); and (d) those that produce a decreased amount of pyruvate (produced by isolating a mutant resistant to an inhibitor of mitochondrial transport, thus decreasing the amount of diacetyl). Given that sake yeasts perform sexual reproduction, sporulation and mating are potent approaches for their breeding. Recently, the genome sequences of sake yeasts have been determined and made publicly accessible. By utilizing this information, the quantitative trait loci (QTLs) for the brewing characteristics of sake yeasts have been identified, which paves a way to DNA marker-assisted selection of the mated strains. Genetic engineering technologies for experimental yeast strains have recently been established by academic groups, and these technologies have also been applied to the breeding of sake yeasts. Sake yeasts whose genomes have been modified with these technologies correspond to genetically modified organisms (GMOs

Influence of the Culture Medium in Dose-Response Effect of the Chlorhexidine on Streptococcus mutans Biofilms

PubMed Central

de Queiroz, Vanessa Salvadego; Ccahuana-Vásquez, Renzo Alberto; Tedesco, Alcides Fabiano; Lyra, Luzia; Cury, Jaime Aparecido; Schreiber, Angélica Zaninelli

2016-01-01

The aim of this study was to evaluate the influence of culture medium on dose-response effect of chlorhexidine (CHX) on Streptococcus mutans UA159 biofilm and validate the use of the cation-adjusted-Müller-Hinton broth (MH) for the evaluation of antibacterial activity. Ultrafiltered Tryptone-Yeast Extract Broth (UTYEB) was compared against MH and MH with blood supplementation (MHS). For each medium, six groups (n = 4) were assessed: two negative control groups (baseline 48 and 120 h) and four experimental groups (0.0001, 0.001, 0.012, and 0.12% CHX). S. mutans biofilm grew on glass slides of each media containing 1% sucrose. After 48 h of growth, biofilms of baseline 48 h were collected and the other groups were treated for 1 min, twice a day, for 3 days, with their respective treatments. The media were changed daily and pH was measured. After 120 h, biofilms were collected and dry weight and viable microorganisms were determined. Results showed CHX dose-response effect being observed in all media for all the variables. However, MH and MHS showed higher sensitivity than UTYEB (p < 0.05). We can conclude that the culture medium does influence dose-response effect of CHX on Streptococcus mutans biofilm and that MH can be used for antibacterial activity. PMID:27293967

Identification of salivary components that induce transition of hyphae to yeast in Candida albicans.

PubMed

Leito, Jelani T D; Ligtenberg, Antoon J M; Nazmi, Kamran; Veerman, Enno C I

2009-10-01

Candida albicans, the major human fungal pathogen, undergoes a reversible morphological transition from single yeast cells to pseudohyphae and hyphae filaments. The hyphae form is considered the most invasive form of the fungus. The purpose of this study is to investigate the effect of saliva on hyphae growth of C. albicans. Candida albicans hyphae were inoculated in Roswell Park Memorial Institute medium with whole saliva, parotid saliva or buffer mimicking the saliva ion composition, and cultured for 18 h at 37 degrees C under aerobic conditions with 5% CO(2). Whole saliva and parotid saliva induced transition to yeast growth, whereas the culture with buffer remained in the hyphae form. Parotid saliva was fractionated on a reverse-phase C8 column and each fraction was tested for inducing transition to yeast growth. By immunoblotting, the salivary component in the active fraction was identified as statherin, a phosphoprotein of 43 amino acids that has been implicated in remineralization of the teeth. Synthetically made statherin induced transition of hyphae to yeast. By deletion of five amino acids at the negatively charged N-terminal site (DpSpSEE), yeast-inducing activity and binding to C. albicans were increased. In conclusion, statherin induces transition to yeast of C. albicans hyphae and may thus contribute to the oral defense against candidiasis.

Screening and characterization of amylase and cellulase activities in psychrotolerant yeasts.

PubMed

Carrasco, Mario; Villarreal, Pablo; Barahona, Salvador; Alcaíno, Jennifer; Cifuentes, Víctor; Baeza, Marcelo

2016-02-19

Amylases and cellulases have great potential for application in industries such as food, detergent, laundry, textile, baking and biofuels. A common requirement in these fields is to reduce the temperatures of the processes, leading to a continuous search for microorganisms that secrete cold-active amylases and cellulases. Psychrotolerant yeasts are good candidates because they inhabit cold-environments. In this work, we analyzed the ability of yeasts isolated from the Antarctic region to grow on starch or carboxymethylcellulose, and their potential extracellular amylases and cellulases. All tested yeasts were able to grow with soluble starch or carboxymethylcellulose as the sole carbon source; however, not all of them produced ethanol by fermentation of these carbon sources. For the majority of the yeast species, the extracellular amylase or cellulase activity was higher when cultured in medium supplemented with glucose rather than with soluble starch or carboxymethylcellulose. Additionally, higher amylase activities were observed when tested at pH 5.4 and 6.2, and at 30-37 °C, except for Rhodotorula glacialis that showed elevated activity at 10-22 °C. In general, cellulase activity was high until pH 6.2 and between 22-37 °C, while the sample from Mrakia blollopis showed high activity at 4-22 °C. Peptide mass fingerprinting analysis of a potential amylase from Tetracladium sp. of about 70 kDa, showed several peptides with positive matches with glucoamylases from other fungi. Almost all yeast species showed extracellular amylase or cellulase activity, and an inducing effect by the respective substrate was observed in a minor number of yeasts. These enzymatic activities were higher at 30 °C in most yeast, with highest amylase and cellulase activity in Tetracladium sp. and M. gelida, respectively. However, Rh. glacialis and M. blollopis displayed high amylase or cellulase activity, respectively, under 22 °C. In this sense, these yeasts are interesting

Quantitative analysis of morphological changes in yeast colonies growing on solid medium: the eccentricity and Fourier indices.

PubMed

Gil de Prado, Elena; Rivas, Eva-María; de Silóniz, María-Isabel; Diezma, Belén; Barreiro, Pilar; Peinado, José M

2014-11-01

The colony shape of four yeast species growing on agar medium was measured for 116 days by image analysis. Initially, all the colonies are circular, with regular edges. The loss of circularity can be quantitatively estimated by the eccentricity index, Ei , calculated as the ratio between their orthogonal vertical and horizontal diameters. Ei can increase from 1 (complete circularity) to a maximum of 1.17-1.30, depending on the species. One colony inhibits its neighbour only when it has reached a threshold area. Then, Ei of the inhibited colony increases proportionally to the area of the inhibitory colony. The initial distance between colonies affects those threshold values but not the proportionality, Ei /area; this inhibition affects the shape but not the total surface of the colony. The appearance of irregularities in the edges is associated, in all the species, not with age but with nutrient exhaustion. The edge irregularity can be quantified by the Fourier index, Fi , calculated by the minimum number of Fourier coefficients that are needed to describe the colony contour with 99% fitness. An ad hoc function has been developed in Matlab v. 7.0 to automate the computation of the Fourier coefficients. In young colonies, Fi has a value between 2 (circumference) and 3 (ellipse). These values are maintained in mature colonies of Debaryomyces, but can reach values up to 14 in Saccharomyces. All the species studied showed the inhibition of growth in facing colony edges, but only three species showed edge irregularities associated with substrate exhaustion. Copyright © 2014 John Wiley & Sons, Ltd.

Short-term outcomes of small-incision lenticule extraction (SMILE) for low, medium, and high myopia.

PubMed

Fernández, Joaquín; Valero, Almudena; Martínez, Javier; Piñero, David P; Rodríguez-Vallejo, Manuel

2017-03-10

To determine the safety, efficacy, and predictability of small-incision lenticule extraction at 6-month follow-up, depending on the level of the myopic refractive error. The surgeries were performed by a surgeon new to this technique. Seventy-one subjects with a mean age of 31.86 ± 5.57 years were included in this retrospective observational study. Subjects were divided into 3 groups depending on the preoperative spherical equivalent (SE): low group from -1.00 D to -3.00 D, medium from -3.25 D to -5.00 D, and high from -5.25 D to -7.00 D. Manifest refraction, corrected distance visual acuity (CDVA), and uncorrected distance visual acuity (UDVA) were measured before surgery and at 6 months after the treatment. In total, 1.4% of the eyes lost 1 line of CDVA after the procedure, whereas 95.8% remained unchanged and 2.8% gained 1 line. A significant undercorrection (p = 0.031) was found in the high myopia group (median -0.50 D), whereas the low and medium groups remained near to emmetropia. In terms of efficacy, no statistically significant intergroup differences for postoperative UDVA (p = 0.282) were found. The vector analysis also showed undercorrection of the preoperative cylinder, even though the standard deviations decreased from 0.9 D in the x axis and 0.7 D in the y axis to 0.24 D and 0.27 D, respectively. Small-incision lenticule extraction might be a safe, effective, and predictable procedure even for inexperienced surgeons. No differences in efficacy were found among myopia levels even though undercorrections were found for SE and cylinder in high myopia.

Prions in Yeast

PubMed Central

Liebman, Susan W.; Chernoff, Yury O.

2012-01-01

The concept of a prion as an infectious self-propagating protein isoform was initially proposed to explain certain mammalian diseases. It is now clear that yeast also has heritable elements transmitted via protein. Indeed, the “protein only” model of prion transmission was first proven using a yeast prion. Typically, known prions are ordered cross-β aggregates (amyloids). Recently, there has been an explosion in the number of recognized prions in yeast. Yeast continues to lead the way in understanding cellular control of prion propagation, prion structure, mechanisms of de novo prion formation, specificity of prion transmission, and the biological roles of prions. This review summarizes what has been learned from yeast prions. PMID:22879407

Evaluation of cashew apple juice for surfactin production by Bacillus subtilis LAMI008.

PubMed

Ponte Rocha, Maria Valderez; Gomes Barreto, Raphaela V; Melo, Vânia Maria M; Barros Gonçalves, Luciana Rocha

2009-05-01

Bacillus subtilis LAMI008 strain isolated from the tank of Chlorination at the Wastewater Treatment Plant on Campus do Pici in Federal University of Ceará, Brazil has been screened for surfactin production in mineral medium containing clarified cashew apple juice (MM-CAJC). Results were compared with the ones obtained using mineral medium with glucose PA as carbon source. The influence on growth and surfactin production of culture medium supplementation with yeast extract was also studied. The substrate concentration analysis indicated that B. subtilis LAMI008 was able to degrade all carbon sources studied and produce biosurfactant. The highest reduction in surface tension was achieved with the fermentation of MM-CAJC, supplemented with yeast extract, which decreased from 58.95 +/- 0.10 to 38.10 +/- 0.81 dyn cm(-1). The biosurfactant produced was capable of emulsifying kerosene, achieving an emulsification index of 65%. Surfactin concentration of 3.5 mg L(-1) was obtained when MM-CAJC, supplemented with yeast extract, was used, thus indicating that it is feasible to produce surfactin from clarified cashew apple juice, a renewable and low-cost carbon source.

Compositional Shift in Fatty Acid Profiles of Lipids Obtained from Oleaginous Yeasts upon the Addition of Essential Oil from Citrus sinensis L.

PubMed

Uprety, Bijaya K; Rakshit, Sudip K

2017-12-01

Tailoring lipids from oleaginous yeasts to contain specific types of fatty acid is of considerable interest to food, fuel, and pharmaceutical industries. In this study, the essential oil obtained from Citrus sinesus L. has been used to alter the fatty acid composition of two common oleaginous yeasts, Rhodosporidium toruloides and Cryptococcus curvatus. With increasing levels of essential oil in the medium, the metabolic flux of the fatty acid biosynthesis pathway shifted towards saturated fatty acid production. Essential oil reduced the activities of elongase and ∆9 desaturase. This made the lipid obtained from both these yeasts rich in saturated fatty acids. At certain specific concentrations of the essential oil in the medium, the lipid obtained from R. toruloides and C. curvatus cultures was similar to mahuwa butter and palm oil, respectively. Limonene is the major constituents of orange essential oil. Its effect on one of the oleaginous yeasts, R. toruloides, was also studied separately. Effects similar to orange essential oil were obtained with limonene. Thus, we can conclude that limonene in orange essential oil brings about compositional change of microbial lipid produced in this organism.

Tol1, a fission yeast phosphomonoesterase, is an in vivo target of lithium, and its deletion leads to sulfite auxotrophy.

PubMed

Miyamoto, R; Sugiura, R; Kamitani, S; Yada, T; Lu, Y; Sio, S O; Asakura, M; Matsuhisa, A; Shuntoh, H; Kuno, T

2000-07-01

Lithium is the drug of choice for the treatment of bipolar affective disorder. The identification of an in vivo target of lithium in fission yeast as a model organism may help in the understanding of lithium therapy. For this purpose, we have isolated genes whose overexpression improved cell growth under high LiCl concentrations. Overexpression of tol1(+), one of the isolated genes, increased the tolerance of wild-type yeast cells for LiCl but not for NaCl. tol1(+) encodes a member of the lithium-sensitive phosphomonoesterase protein family, and it exerts dual enzymatic activities, 3'(2'),5'-bisphosphate nucleotidase and inositol polyphosphate 1-phosphatase. tol1(+) gene-disrupted cells required high concentrations of sulfite in the medium for growth. Consistently, sulfite repressed the sulfate assimilation pathway in fission yeast. However, tol1(+) gene-disrupted cells could not fully recover from their growth defect and abnormal morphology even when the medium was supplemented with sulfite, suggesting the possible implication of inositol polyphosphate 1-phosphatase activity for cell growth and morphology. Given the remarkable functional conservation of the lithium-sensitive dual-specificity phosphomonoesterase between fission yeast and higher-eukaryotic cells during evolution, it may represent a likely in vivo target of lithium action across many species.

One-Cell Doubling Evaluation by Living Arrays of Yeast, ODELAY!

DOE PAGES

Herricks, Thurston; Dilworth, David J.; Mast, Fred D.; ...

2016-11-16

Cell growth is a complex phenotype widely used in systems biology to gauge the impact of genetic and environmental perturbations. Due to the magnitude of genome-wide studies, resolution is often sacrificed in favor of throughput, creating a demand for scalable, time-resolved, quantitative methods of growth assessment. We present ODELAY (One-cell Doubling Evaluation by Living Arrays of Yeast), an automated and scalable growth analysis platform. High measurement density and single-cell resolution provide a powerful tool for large-scale multiparameter growth analysis based on the modeling of microcolony expansion on solid media. Pioneered in yeast but applicable to other colony forming organisms, ODELAYmore » extracts the three key growth parameters (lag time, doubling time, and carrying capacity) that define microcolony expansion from single cells, simultaneously permitting the assessment of population heterogeneity. The utility of ODELAY is illustrated using yeast mutants, revealing a spectrum of phenotypes arising from single and combinatorial growth parameter perturbations.« less

One-Cell Doubling Evaluation by Living Arrays of Yeast, ODELAY!

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herricks, Thurston; Dilworth, David J.; Mast, Fred D.

Cell growth is a complex phenotype widely used in systems biology to gauge the impact of genetic and environmental perturbations. Due to the magnitude of genome-wide studies, resolution is often sacrificed in favor of throughput, creating a demand for scalable, time-resolved, quantitative methods of growth assessment. We present ODELAY (One-cell Doubling Evaluation by Living Arrays of Yeast), an automated and scalable growth analysis platform. High measurement density and single-cell resolution provide a powerful tool for large-scale multiparameter growth analysis based on the modeling of microcolony expansion on solid media. Pioneered in yeast but applicable to other colony forming organisms, ODELAYmore » extracts the three key growth parameters (lag time, doubling time, and carrying capacity) that define microcolony expansion from single cells, simultaneously permitting the assessment of population heterogeneity. The utility of ODELAY is illustrated using yeast mutants, revealing a spectrum of phenotypes arising from single and combinatorial growth parameter perturbations.« less

Combinatorial effect of mutagenesis and medium component optimization on Bacillus amyloliquefaciens antifungal activity and efficacy in eradicating Botrytis cinerea.

PubMed

Masmoudi, Fatma; Ben Khedher, Saoussen; Kamoun, Amel; Zouari, Nabil; Tounsi, Slim; Trigui, Mohamed

2017-04-01

This work is directed towards Bacillus amyloliquefaciens strain BLB371 metabolite production for biocontrol of fungal phytopathogens. In order to maximise antifungal metabolite production by this strain, two approaches were combined: random mutagenesis and medium component optimization. After three rounds of mutagenesis, a hyper active mutant, named M3-7, was obtained. It produces 7 fold more antifungal metabolites (1800AU/mL) than the wild strain in MC medium. A hybrid design was applied to optimise a new medium to enhance antifungal metabolite production by M3-7. The new optimized medium (35g/L of peptone, 32.5g/L of sucrose, 10.5g/L of yeast extract, 2.4g/L of KH 2 PO 4 , 1.3g/L of MgSO 4 and 23mg/L of MnSO 4 ) achieved 1.62 fold enhancement in antifungal compound production (3000AU/mL) by this mutant, compared to that achieved in MC medium. Therefore, combinatory effect of these two approaches (mutagenesis and medium component optimization) allowed 12 fold improvement in antifungal activity (from 250UA/mL to 3000UA/mL). This improvement was confirmed against several phytopathogenic fungi with an increase of MIC and MFC over than 50%. More interestingly, a total eradication of gray mold was obtained on tomato fruits infected by Botrytis cinerea and treated by M3-7, compared to those treated by BLB371. From the practical point of view, combining random mutagenesis and medium optimization could be considered as an excellent tool for obtaining promising biological products useful against phytopathogenic fungi. Copyright © 2017 Elsevier GmbH. All rights reserved.

Technical note: use of internal transcribed spacer for ruminal yeast identification in dairy cows.

PubMed

Vargas-Bello-Pérez, E; Cancino-Padilla, N; Romero, J

2016-12-01

Molecular techniques are important tools for microbiological studies in different habitats, and the internal transcribed spacer (ITS) has been proved to be useful for analyzing fungal diversity. The aim of this study was to use the ITS region to generate ruminal yeast profile and to identify ruminal yeast. DNA from ruminal digesta was extracted to amplify the ribosomal ITS region. The profile from the PCR products was visualized and the excised bands from the profile were identified as the genera Millerozyma, Pichia, Rhizomucor and Hyphopichia. Overall, the ITS resulted to be a simple, fast and sensitive approach that allowed profiling and identification of ruminal yeast that have not been previously described (Millerozyma and Hyphopichia) in the rumen microbial community.

Evaluation of antipyretic potential of Vernonia cinerea extract in rats.

PubMed

Gupta, Malaya; Mazumder, U K; Manikandan, L; Bhattacharya, S; Haldar, P K; Roy, S

2003-08-01

The methanol extract of the whole plant of Vernonia cinerea (MEVC) was evaluated for its antipyretic potential on normal body temperature and yeast-induced pyrexia in rats. MEVC significantly reduced the normal body temperature at doses of 250 and 500 mg/kg body weight p.o. MEVC also lowered the elevated body temperature in the case of yeast-induced pyrexia in a dose dependent manner. The antipyretic effect of the extract at a dose of 500 mg/kg was identical to that of the standard drug paracetamol. Copyright 2003 John Wiley & Sons, Ltd.

Fisetin yeast-based bio-capsules via osmoporation: effects of process variables on the encapsulation efficiency and internalized fisetin content.

PubMed

de Câmara, Antonio Anchieta; Dupont, Sébastien; Beney, Laurent; Gervais, Patrick; Rosenthal, Amauri; Correia, Roberta Targino Pinto; Pedrini, Márcia Regina da Silva

2016-06-01

Osmoporation is an innovative method that can be used with food-grade yeast cells of Saccharomyces cerevisiae as natural encapsulating matrices. This technique overcomes barriers that difficult encapsulation and enables the internalization of fragile bioactive molecules such as fisetin into yeasts. In the present study, we assessed the effects of concentration, osmotic pressure, and temperature on the encapsulation efficiency (EE) and internalized fisetin content (IF). Two different quantification strategies were investigated: direct extraction (DE) without cell washing or freeze-drying steps and indirect extraction (IE) performed after washings with ethanol and freeze-drying. Our results showed that osmoporation improved EE (33 %) and IF (1.199 mg). The best experimental conditions were found by using DE. High-resolution images showed that the yeast cell envelope was preserved during osmoporation at 30 MPa and 84 % of yeast cells remained viable after treatment. Washing cells with organic solvent led to decreased EE (0.65 %) and IF (0.023 mg). This was probably due to either damages caused to yeast cell envelope or fisetin dragged out of cell. Overall, the results demonstrated the adequacy and relevant biotechnological potential of yeasts as encapsulating matrices for hydrophobic compounds. This fresh biotechnological approach has proven to be a promising tool for the production of bioactive-rich food products.

Sulphur tracer experiments in laboratory animals using 34S-labelled yeast.

PubMed

Martínez-Sierra, J Giner; Moreno Sanz, F; Herrero Espílez, P; Marchante Gayón, J M; Rodríguez Fernández, J; García Alonso, J I

2013-03-01

We have evaluated the use of (34)S-labelled yeast to perform sulphur metabolic tracer experiments in laboratory animals. The proof of principle work included the selection of the culture conditions for the preparation of sulphur labelled yeast, the study of the suitability of this labelled yeast as sulphur source for tracer studies using in vitro gastrointestinal digestion and the administration of the (34)S-labelled yeast to laboratory animals to follow the fate and distribution of (34)S in the organism. For in vitro gastrointestinal digestion, the combination of sodium dodecyl sulphate-polyacrylamide gel electrophoresis and high-performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS) showed that labelled methionine, cysteine and other low molecular weight sulphur-containing biomolecules were the major components in the digested extracts of the labelled yeast. Next, in vivo kinetic experiments were performed in healthy Wistar rats after the oral administration of (34)S-labelled yeast. The isotopic composition of total sulphur in tissues, urine and faeces was measured by double-focusing inductively coupled plasma mass spectrometry after microwave digestion. It was observed that measurable isotopic enrichments were detected in all samples. Finally, initial investigations on sulphur isotopic composition of serum and urine samples by HPLC-ICP-MS have been carried out. For serum samples, no conclusive data were obtained. Interestingly, chromatographic analysis of urine samples showed differential isotope enrichment for several sulphur-containing biomolecules.

Characteristics of metal-tolerant plant growth-promoting yeast (Cryptococcus sp. NSE1) and its influence on Cd hyperaccumulator Sedum plumbizincicola.

PubMed

Liu, Wuxing; Wang, Beibei; Wang, Qingling; Hou, Jinyu; Wu, Longhua; Wood, Jennifer L; Luo, Yongming; Franks, Ashley E

2016-09-01

Plant growth-promoting yeasts are often over looked as a mechanism to improve phytoremediation of heavy metals. In this study, Cryptococcus sp. NSE1, a Cd-tolerant yeast with plant growth capabilities, was isolated from the rhizosphere of the heavy metal hyperaccumulator Sedum plumbizincicola. The yeast exhibited strong tolerance to a range of heavy metals including Cd, Cu, and Zn on plate assays. The adsorption rate Cd, Cu, Zn by NSE1 was 26.1, 13.2, and 25.2 %, respectively. Irregular spines were formed on the surface of NSE1 when grown in MSM medium supplemented with 200 mg L(-1) Cd. NSE1 was capable of utilizing 1-aminocyclopropane-1-carboxylate (ACC) as a sole nitrogen source and was capable of solubilization of inorganic phosphate at rates of 195.2 mg L(-1). Field experiments demonstrated that NSE1 increased phytoremediation by increasing the biomass of Cd hyperaccumulator S. plumbizincicola (46 %, p < 0.05) during phytoremediation. Overall, Cd accumulation by S. plumbizincicola was increased from 19.6 to 31.1 mg m(-2) though no difference in the concentration of Cd in the shoot biomass was observed between NSE1 and control. A Cd accumulation ratio of 38.0 % for NSE1 and 17.2 % for control was observed. The HCl-extractable Cd and CaCl2-extractable Cd concentration in the soil of the NSE1 treatment were reduced by 39.2 and 29.5 %, respectively. Community-level physiology profiling, assessed using Biolog Eco plates, indicated functional changes to the rhizosphere community inoculated with NSE1 by average well color development (AWCD) and measurement of richness (diversity). Values of Shannon-Weiner index, Simpson index, and McIntosh index showed a slight but no significant increases. These results indicate that inoculation of NSE1 could increase the shoot biomass of S. plumbizincicola, enhance the Cd accumulation in S. plumbizincicola, and decrease the available heavy metal content in soils significantly without overall significant changes to the

Orthogonal array deciphering MRS medium requirements for isolated Lactobacillus rhamnosus ZY with cell properties characterization.

PubMed

Zhang, Yu; Ng, I-Son; Yao, Chuanyi; Lu, Yinghua

2014-09-01

Lactobacillus rhamnosus is a well-known lactic acid bacterium (LAB), but a new ZY strain was isolated for the first time from commercial probiotic powder recently. Although many studies have focused on developing cost-effective media for the production of LAB, the de Man, Rogosa and Sharpe (MRS) medium is still the most common medium for bioprocesses. The aim of the current study is to decipher the composition of MRS based on a statistical approach, which will allow a higher biomass of Lactobacillus to be obtained. In Taguchi's approach, an L27 orthogonal array was adopted to evaluate the significance of 10 ingredients in MRS, in which the effects of the components were ranked according to their effect on biomass at OD600 as dextrose > MnSO4·H2O > beef extract > CH3COONa > MgSO4 > yeast extract > proteose peptone > K2HPO4 > ammonium citrate > Tween 80. Although the individual trace elements of ammonium citrate, K2HPO4, CH3COONa and MgSO4 in MRS had an insignificant influence on the biomass after statistical analysis, the total elimination of trace elements would predominantly affect the cell growth of Lactobacillus. Further characterization of the cell properties through attenuated total reflectance of Fourier transform infrared (ATR-FTIR) spectroscopy and protein identification via SDS-PAGE coupled with tandem mass spectrometry implied that dextrose as major carbon source in MRS played the most crucial role for L. rhamnosus production. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Novel structural features in Candida albicans hyphal glucan provide a basis for differential innate immune recognition of hyphae versus yeast.

PubMed

Lowman, Douglas W; Greene, Rachel R; Bearden, Daniel W; Kruppa, Michael D; Pottier, Max; Monteiro, Mario A; Soldatov, Dmitriy V; Ensley, Harry E; Cheng, Shih-Chin; Netea, Mihai G; Williams, David L

2014-02-07

The innate immune system differentially recognizes Candida albicans yeast and hyphae. It is not clear how the innate immune system effectively discriminates between yeast and hyphal forms of C. albicans. Glucans are major components of the fungal cell wall and key fungal pathogen-associated molecular patterns. C. albicans yeast glucan has been characterized; however, little is known about glucan structure in C. albicans hyphae. Using an extraction procedure that minimizes degradation of the native structure, we extracted glucans from C. albicans hyphal cell walls. (1)H NMR data analysis revealed that, when compared with reference (1→3,1→6) β-linked glucans and C. albicans yeast glucan, hyphal glucan has a unique cyclical or "closed chain" structure that is not found in yeast glucan. GC/MS analyses showed a high abundance of 3- and 6-linked glucose units when compared with yeast β-glucan. In addition to the expected (1→3), (1→6), and 3,6 linkages, we also identified a 2,3 linkage that has not been reported previously in C. albicans. Hyphal glucan induced robust immune responses in human peripheral blood mononuclear cells and macrophages via a Dectin-1-dependent mechanism. In contrast, C. albicans yeast glucan was a much less potent stimulus. We also demonstrated the capacity of C. albicans hyphal glucan, but not yeast glucan, to induce IL-1β processing and secretion. This finding provides important evidence for understanding the immune discrimination between colonization and invasion at the mucosal level. When taken together, these data provide a structural basis for differential innate immune recognition of C. albicans yeast versus hyphae.

Novel Structural Features in Candida albicans Hyphal Glucan Provide a Basis for Differential Innate Immune Recognition of Hyphae Versus Yeast*

PubMed Central

Lowman, Douglas W.; Greene, Rachel R.; Bearden, Daniel W.; Kruppa, Michael D.; Pottier, Max; Monteiro, Mario A.; Soldatov, Dmitriy V.; Ensley, Harry E.; Cheng, Shih-Chin; Netea, Mihai G.; Williams, David L.

2014-01-01

The innate immune system differentially recognizes Candida albicans yeast and hyphae. It is not clear how the innate immune system effectively discriminates between yeast and hyphal forms of C. albicans. Glucans are major components of the fungal cell wall and key fungal pathogen-associated molecular patterns. C. albicans yeast glucan has been characterized; however, little is known about glucan structure in C. albicans hyphae. Using an extraction procedure that minimizes degradation of the native structure, we extracted glucans from C. albicans hyphal cell walls. 1H NMR data analysis revealed that, when compared with reference (1→3,1→6) β-linked glucans and C. albicans yeast glucan, hyphal glucan has a unique cyclical or “closed chain” structure that is not found in yeast glucan. GC/MS analyses showed a high abundance of 3- and 6-linked glucose units when compared with yeast β-glucan. In addition to the expected (1→3), (1→6), and 3,6 linkages, we also identified a 2,3 linkage that has not been reported previously in C. albicans. Hyphal glucan induced robust immune responses in human peripheral blood mononuclear cells and macrophages via a Dectin-1-dependent mechanism. In contrast, C. albicans yeast glucan was a much less potent stimulus. We also demonstrated the capacity of C. albicans hyphal glucan, but not yeast glucan, to induce IL-1β processing and secretion. This finding provides important evidence for understanding the immune discrimination between colonization and invasion at the mucosal level. When taken together, these data provide a structural basis for differential innate immune recognition of C. albicans yeast versus hyphae. PMID:24344127

Optimization of flask culture medium and conditions for hyaluronic acid production by a Streptococcus equisimilis mutant nc2168.

PubMed

Chen, Yong-Hao; Li, Jun; Liu, Li; Liu, Hong-Zhi; Wang, Qiang

2012-10-01

A mutant designated NC2168, which was selected from wild-type Streptococcus equisimilis CVCC55116 by ultraviolet ray combined with(60)Co-γ ray treatment and does not produce streptolysin, was employed to produce hyaluronic acid (HA). In order to increase the output of HA in a flask, the culture medium and conditions for NC2168 were optimized in this study. The influence of culture medium ingredients including carbon sources, nitrogen sources and metal ions on HA production was evaluated using factional factorial design. The mathematical model, which represented the effect of each medium component and their interaction on the yield of HA, was established by the quadratic rotary combination design and response surface method. The model estimated that, a maximal yield of HA could be obtained when the concentrations of yeast extract, peptone, glucose, and MgSO4 were set at 3 g/100 mL, 2 g/100 mL, 0.5 g/100 mL and 0.15 g/100 mL, respectively. Compared with the values obtained by other runs in the experimental design, the optimized medium resulted in a remarkable increase in the output of HA and the maximum of the predicted HA production was 174.76 mg/L. The model developed was accurate and reliable for predicting the production of HA by NC2168.Cultivation conditions were optimized by an orthogonal experimental design and the optimal conditions were as follows: temperature 33°C, pH 7.8, agitation speed 200 rpm, medium volume 20 mL.

Diagnostic medium containing inositol, urea, and caffeic acid for selective growth of Cryptococcus neoformans.

PubMed Central

Healy, M E; Dillavou, C L; Taylor, G E

1977-01-01

An agar medium containing inositol and urea as sole carbon and nitrogen sources, caffeic acid and ferric citrate as agents for the selective pigmentation of Cryptococcus neoformans, gentamicin as a broad-spectrum bacterial antibiotic, and yeast nitrogen base without amino acids and ammonium sulfate (Difco) was tested against 137 clinical isolates, 4 survey specimens, and 11 ATCC yeast and yeast-like strains. All 28 strains of C. neoformans showed heavy growth and dark brown pigmentation after 36 h. All other tested species of Cryptococcus showed heavy growth after 36 h but only light brown pigmentation after 48 h. No growth was observed in any tested strains of Geotrichum, Pityrosporum, Rhodotorula, Saccharomyces, and Torulopsis. Only the Cryptococcus-like Candida humicola grew of the 8 species and 62 strains of Candida tested. Six of 15 strains of Trichosporon cutaneum and 1 of 2 strains of Trichosporon pullulans showed moderate growth after 48 h. Very different colonial and microscopic morphology and/or the absence of brown pigmentation easily differentiated these strains of T. cutaneum, T. pullulans, and C. humicola from C. neoformans. The growth- and pigmentation-providing characteristics of the medium were unaffected by 2 h of exposure to 254 nm of ultraviolet light. PMID:334795

Formation by yeast of 2-furanmethanethiol and ethyl 2-mercaptopropionate aroma compounds in Japanese soy sauce.

PubMed

Meng, Qi; Hatakeyama, Makoto; Sugawara, Etsuko

2014-01-01

Two aroma compounds of volatile thiols, 2-furanmethanethiol (2FM) and ethyl 2-mercaptopropionate (ET2MP), were formed in five types of Japanese soy sauce during fermentation by yeast. The concentrations of 2FM and ET2MP in the soy sauce samples increased during alcoholic fermentation. The concentrations of 2FM and ET2MP were higher in the soy sauce fermented by Zygosaccharomyces rouxii than in that fermented by Candida versatilis. The enantiomers of ET2MP were separated by gas chromatography in a capillary column. The average enantiomeric ratio of ET2MP in the soy sauce was approximately 1:1. 2FM was formed by yeast in a medium prepared from cysteine and furfural, and cysteine is considered the key precursor of 2FM by yeast in soy sauce.

A novel method to prepare L-Arabinose from xylose mother liquor by yeast-mediated biopurification

PubMed Central

2011-01-01

Background L-arabinose is an important intermediate for anti-virus drug synthesis and has also been used in food additives for diets-controlling in recent years. Commercial production of L-arabinose is a complex progress consisting of acid hydrolysis of gum arabic, followed by multiple procedures of purification, thus making high production cost. Therefore, there is a biotechnological and commercial interest in the development of new cost-effective and high-performance methods for obtaining high purity grade L-arabinose. Results An alternative, economical method for purifying L-arabinose from xylose mother liquor was developed in this study. After screening 306 yeast strains, a strain of Pichia anomala Y161 was selected as it could effectively metabolize other sugars but not L-arabinose. Fermentation in a medium containing xylose mother liquor permitted enrichment of L-arabinose by a significant depletion of other sugars. Biochemical analysis of this yeast strain confirmed that its poor capacity for utilizing L-arabinose was due to low activities of the enzymes required for the metabolism of this sugar. Response surface methodology was employed for optimization the fermentation conditions in shake flask cultures. The optimum conditions were: 75 h fermentation time, at 32.5°C, in a medium containing 21% (v/v) xylose mother liquor. Under these conditions, the highest purity of L-arabinose reached was 86.1% of total sugar, facilitating recovery of white crystalline L-arabinose from the fermentation medium by simple methods. Conclusion Yeast-mediated biopurification provides a dynamic method to prepare high purity of L-arabinose from the feedstock solution xylose mother liqour, with cost-effective and high-performance properties. PMID:21649890

Use of soybean vinasses as a germinant medium for a Geobacillus stearothermophilus ATCC 7953 sterilization biological indicator.

PubMed

Dlugokenski, Regina E F; Sella, Sandra R B R; Guizelini, Belquis P; Vandenberghe, Luciana P S; Woiciechowski, Adenise L; Soccol, Carlos R; Minozzo, João C

2011-04-01

A novel low-cost medium was developed from by-products and wastes from the ethanol agro-industry to replace commercial media in the production of a steam sterilization biological indicator (BI). Various recovery media were developed using soybean or sugarcane molasses and vinasse to prepare a self-contained BI. Media performance was evaluated by viability and heat resistance (D(121 °C) value) according to regulatory standards. A medium produced with a soybean vinasse ratio of 1:70 (1.4%) (w/v) produced the results, with D(121 °C)=2.9±0.5 min and Usk=12.7±2.1 min. The addition of 0.8% (w/v) yeast extract improved the germination of heat-damaged spores. The pH variation from 6.0 to 7.3 resulted in a gradual increase in the D(121 °C) value. The absence of calcium chloride resulted in a decrease in germination, while no significant differences were observed with starch addition. Soybean vinasses may thus be used as the main component of a culture medium to substitute for commercial media in the production of self-contained biological indicators. The use of ethanol production waste in this biotechnological process realized a reliable performance, minimized the environmental impact, and decreased BI production costs while producing a high quality product. © Springer-Verlag 2011

Yeast for virus research

PubMed Central

Zhao, Richard Yuqi

2017-01-01

Budding yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe) are two popular model organisms for virus research. They are natural hosts for viruses as they carry their own indigenous viruses. Both yeasts have been used for studies of plant, animal and human viruses. Many positive sense (+) RNA viruses and some DNA viruses replicate with various levels in yeasts, thus allowing study of those viral activities during viral life cycle. Yeasts are single cell eukaryotic organisms. Hence, many of the fundamental cellular functions such as cell cycle regulation or programed cell death are highly conserved from yeasts to higher eukaryotes. Therefore, they are particularly suited to study the impact of those viral activities on related cellular activities during virus-host interactions. Yeasts present many unique advantages in virus research over high eukaryotes. Yeast cells are easy to maintain in the laboratory with relative short doubling time. They are non-biohazardous, genetically amendable with small genomes that permit genome-wide analysis of virologic and cellular functions. In this review, similarities and differences of these two yeasts are described. Studies of virologic activities such as viral translation, viral replication and genome-wide study of virus-cell interactions in yeasts are highlighted. Impacts of viral proteins on basic cellular functions such as cell cycle regulation and programed cell death are discussed. Potential applications of using yeasts as hosts to carry out functional analysis of small viral genome and to develop high throughput drug screening platform for the discovery of antiviral drugs are presented. PMID:29082230

Influence of culture conditions and medium composition on the production of antibacterial compounds by marine Serratia sp. WPRA3.

PubMed

Jafarzade, Mahtab; Yahya, Nur Ain; Shayesteh, Fatemeh; Usup, Gires; Ahmad, Asmat

2013-06-01

This study was undertaken to investigate the influence of culture conditions and medium components on production of antibacterial compounds by Serratia sp. WPRA3 (JX020764) which was isolated from marine water of Port Dickson, Malaysia. Biochemical, morphological, and molecular characteristics suggested that the isolate is a new candidate of the Serratia sp. The isolate showed strong antimicrobial activity against fungi, Gram-negative and Gram-positive bacteria. This bacterium exhibited optimum antibacterial compounds production at 28°C, pH 7 and 200 rev/min aeration during 72 h of incubation period. Highest antibacterial activity was obtained when sodium chloride (2%), yeast extract (0.5%), and glucose concentration (0.75%) were used as salt, nitrogen, and carbon sources respectively. Different active fractions were obtained by Thin-Layer Chromatography (TLC) and Flash Column Chromatography (FCC) from ethyl acetate crude extracts namely OCE and RCE in different culture conditions, OCE (pH 5, 200 rev/min) and RCE (pH 7/without aeration). In conclusion, the results suggested different culture conditions have a significant impact on the types of secondary metabolites produced by the bacterium.

S-adenosylmethionine decarboxylase from baker's yeast.

PubMed Central

Pösö, H; Sinervirta, R; Jänne, J

1975-01-01

1. S-Adenosyl-L-methionine decarboxylase (S-adenosyl-L-methionine carboxy-lyase, EC 4.1.1.50) was purified more than 1100-fold from extracts of Saccharomyces cerevisiae by affinity chromatography on columns of Sepharose containing covalently bound methylglyoxal bis(guanylhydrazone) (1,1'[(methylethanediylidene)dinitrilo]diguanidine) [Pegg, (1974) Biochem J. 141, 581-583]. The final preparation appeared to be homogeneous on polyacrylamide-gel electrophoresis at pH 8.4. 2. S-Adenosylmethionine decarboxylase activity was completely separated from spermidine synthase activity [5'-deoxyadenosyl-(5'),3-aminopropyl-(1),methylsulphonium-salt-putrescine 3-aminopropyltransferase, EC 2.5.1.16] during the purification procedure. 3. Adenosylmethionine decarboxylase activity from crude extracts of baker's yeast was stimulated by putrescine, 1,3-diamino-propane, cadaverine (1,5-diaminopentane) and spermidine; however, the purified enzyme, although still stimulated by the diamines, was completely insensitive to spermidine. 4. Adenosylmethionine decarboxylase has an apparent Km value of 0.09 mM for adenosylmethionine in the presence of saturating concentrations of putrescine. The omission of putrescine resulted in a five-fold increase in the apparent Km value for adenosylmethionine. 5. The apparent Ka value for putrescine, as the activator of the reaction, was 0.012 mM. 6. Methylglyoxal bis(guanylhydrazone) and S-methyladenosylhomocysteamine (decarboxylated adenosylmethionine) were powerful inhibitors of the enzyme. 7. Adenosylmethionine decarboxylase from baker's yeast was inhibited by a number of conventional carbonyl reagents, but in no case could the inhibition be reversed with exogenous pyridoxal 5'-phosphate. PMID:1108876

Dynamic study of yeast species and Saccharomyces cerevisiae strains during the spontaneous fermentations of Muscat blanc in Jingyang, China.

PubMed

Wang, Chunxiao; Liu, Yanlin

2013-04-01

The evolution of yeast species and Saccharomyces cerevisiae genotypes during spontaneous fermentations of Muscat blanc planted in 1957 in Jingyang region of China was followed in this study. Using a combination of colony morphology on Wallerstein Nutrient (WLN) medium, sequence analysis of the 26S rDNA D1/D2 domain and 5.8S-ITS-RFLP analysis, a total of 686 isolates were identified at the species level. The six species identified were S. cerevisiae, Hanseniaspora uvarum, Hanseniaspora opuntiae, Issatchenkia terricola, Pichia kudriavzevii (Issatchenkia orientalis) and Trichosporon coremiiforme. This is the first report of T. coremiiforme as an inhabitant of grape must. Three new colony morphologies on WLN medium and one new 5.8S-ITS-RFLP profile are described. Species of non-Saccharomyces, predominantly H. opuntiae, were found in early stages of fermentation. Subsequently, S. cerevisiae prevailed followed by large numbers of P. kudriavzevii that dominated at the end of fermentations. Six native genotypes of S. cerevisiae were determined by interdelta sequence analysis. Genotypes III and IV were predominant. As a first step in exploring untapped yeast resources of the region, this study is important for monitoring the yeast ecology in native fermentations and screening indigenous yeasts that will produce wines with regional characteristics. Copyright © 2012 Elsevier Ltd. All rights reserved.

Suitability of peracetic acid for sterilization of media for mycoplasma cultures.

PubMed Central

Wutzler, P; Sprössig, M; Peterseim, H

1975-01-01

The utility of peracetic acid for sterilization of serum and yeast extract additions to mycoplasma medium was studied by culturing six Mycoplasma species. Culture media containing additions that had been sterilized with peracetic acid proved to be as good as filtered components. The use of 0.05 to 0.1% peracetic acid is recommended to sterilize the serum and yeast extract additions since savings in time and equipment can be accomplished. PMID:1100656

Malassezia yeasts produce a collection of exceptionally potent activators of the Ah (dioxin) receptor detected in diseased human skin

PubMed Central

Magiatis, Prokopios; Pappas, Periklis; Gaitanis, George; Mexia, Nikitia; Melliou, Eleni; Galanou, Maria; Vlachos, Christophoros; Stathopoulou, Konstantina; Skaltsounis, Alexios Leandros; Marselos, Marios; Velegraki, Aristea; Denison, Michael S.; Bassukas, Ioannis D.

2013-01-01

Malassezia yeasts are commensal microorganisms which under insufficiently understood conditions can become pathogenic. We have previously shown that specific strains isolated from diseased human skin can preferentially produce agonists of the aryl hydrocarbon receptor (AhR), whose activation has been linked to certain skin diseases. Investigation of skin scale extracts from patients with Malassezia associated diseases demonstrated 10–1000 fold higher AhR activating capacity than control skin extracts. LC/MS/MS analysis of the patients’ extracts revealed the presence of indirubin, 6-formylindolo[3,2-b]carbazole (FICZ), indolo[3,2-b]carbazole (ICZ), malassezin, and pityriacitrin. The same compounds were also identified in 9/12 Malassezia species culture extracts tested, connecting their presence in skin scales with this yeast. Studying the activity of the Malassezia culture-extracts and pure metabolites in HaCaT cells by Reverse Transcriptase Real-Time PCR revealed significant alterations in mRNA levels of the endogenous AhR-responsive genes Cyp1A1, Cyp1B1 and AhRR. Indirubin and FICZ activated AhR in HaCaT and human HepG2 cells with significantly higher, yet transient, potency as compared to the prototypical AhR ligand, dioxin. In loco synthesis of these highly potent AhR inducers by Malassezia yeasts could have a significant impact on skin homeostatic mechanisms and disease development. PMID:23448877

Malassezia yeasts produce a collection of exceptionally potent activators of the Ah (dioxin) receptor detected in diseased human skin.

PubMed

Magiatis, Prokopios; Pappas, Periklis; Gaitanis, George; Mexia, Nikitia; Melliou, Eleni; Galanou, Maria; Vlachos, Christophoros; Stathopoulou, Konstantina; Skaltsounis, Alexios Leandros; Marselos, Marios; Velegraki, Aristea; Denison, Michael S; Bassukas, Ioannis D

2013-08-01

Malassezia yeasts are commensal microorganisms, which under insufficiently understood conditions can become pathogenic. We have previously shown that specific strains isolated from diseased human skin can preferentially produce agonists of the aryl hydrocarbon receptor (AhR), whose activation has been linked to certain skin diseases. Investigation of skin scale extracts from patients with Malassezia-associated diseases demonstrated 10- to 1,000-fold higher AhR-activating capacity than control skin extracts. Liquid chromatography-tandem mass spectrometry analysis of the patients' extracts revealed the presence of indirubin, 6-formylindolo[3,2-b]carbazole (FICZ), indolo[3,2-b]carbazole (ICZ), malassezin, and pityriacitrin. The same compounds were also identified in 9 out of 12 Malassezia species culture extracts tested, connecting their presence in skin scales with this yeast. Studying the activity of the Malassezia culture extracts and pure metabolites in HaCaT cells by reverse transcriptase real-time PCR revealed significant alterations in mRNA levels of the endogenous AhR-responsive genes Cyp1A1, Cyp1B1, and AhRR. Indirubin- and FICZ-activated AhR in HaCaT and human HepG2 cells with significantly higher, yet transient, potency as compared with the prototypical AhR ligand, dioxin. In loco synthesis of these highly potent AhR inducers by Malassezia yeasts could have a significant impact on skin homeostatic mechanisms and disease development.

L-arabinose fermenting yeast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Min; Singh, Arjun; Suominen, Pirkko

An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. A yeast strain engineered to metabolize arabinose through a novel pathway is also disclosed. Methods of producing ethanol include utilizing these modified yeast strains.

L-arabinose fermenting yeast

DOEpatents

Zhang, Min; Singh, Arjun; Suominen, Pirkko; Knoshaug, Eric; Franden, Mary Ann; Jarvis, Eric

2014-09-23

An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. A yeast strain engineered to metabolize arabinose through a novel pathway is also disclosed. Methods of producing ethanol include utilizing these modified yeast strains.

Radiation-induced mitotic and meiotic aneuploidy in the yeast Saccharomyces cerevisiae.

PubMed

Parry, J M; Sharp, D; Tippins, R S; Parry, E M

1979-06-01

A number of genetic systems are described which in yeast may be used to monitor the induction of chromosome aneuploidy during both mitotic and meiotic cell division. Using these systems we have been able to demonstrate the induction of both monosomic and trisomic cells in mitotically dividing cells and disomic spores in meiotically dividing cells after both UV light and X-ray exposure. The frequency of UV-light-induced monosomic colonies were reduced by post-treatment with photoreactivity light and both UV-light- and X-ray-induced monosomic colonies were reduced by liquid holding post-treatment under non-nutrient conditions. Both responses indicate an involvement of DNA-repair mechanisms in the removal of lesions which may lead to monosomy in yeast. This was further confirmed by the response of an excision-defective yeast strain which showed considerably increased sensitivity to the induction of monosomic colonies by UV-light treatment at low doses. Yeast cultures irradiated at different stages of growth showed variation in their responses to both UV-light and X-rays, cells at the exponential phase of growth show maximum sensitivity to the induction of monosomic colonies at low doses whereas stationary phase cultures showed maximum induction of monosomic colonies at high does. The frequencies of X-ray-induced chromosome aneuploidy during meiosis leading to the production of disomic spores was shown to be dependent upon the stage of meiosis at which the yeast cells were exposed to radiation. Cells which had proceeded beyond the DNA synthetic stage of meiosis were shown to produce disomic spores at considerably lower radiation doses than those cells which had only recently been inoculated into sporulation medium. The results obtained suggest that the yeast sustem may be suitable for the study of sensitivities of the various stages of meiotic cell division to the induction of chromosome aneuploidy after radiation exposure.

Prevention of Yeast Spoilage in Feed and Food by the Yeast Mycocin HMK

PubMed Central

Lowes, K. F.; Shearman, C. A.; Payne, J.; MacKenzie, D.; Archer, D. B.; Merry, R. J.; Gasson, M. J.

2000-01-01

The yeast Williopsis mrakii produces a mycocin or yeast killer toxin designated HMK; this toxin exhibits high thermal stability, high pH stability, and a broad spectrum of activity against other yeasts. We describe construction of a synthetic gene for mycocin HMK and heterologous expression of this toxin in Aspergillus niger. Mycocin HMK was fused to a glucoamylase protein carrier, which resulted in secretion of biologically active mycocin into the culture media. A partial purification protocol was developed, and a comparison with native W. mrakii mycocin showed that the heterologously expressed mycocin had similar physiological properties and an almost identical spectrum of biological activity against a number of yeasts isolated from silage and yoghurt. Two food and feed production systems prone to yeast spoilage were used as models to assess the ability of mycocin HMK to act as a biocontrol agent. The onset of aerobic spoilage in mature maize silage was delayed by application of A. niger mycocin HMK on opening because the toxin inhibited growth of the indigenous spoilage yeasts. This helped maintain both higher lactic acid levels and a lower pH. In yoghurt spiked with dairy spoilage yeasts, A. niger mycocin HMK was active at all of the storage temperatures tested at which yeast growth occurred, and there was no resurgence of resistant yeasts. The higher the yeast growth rate, the more effective the killing action of the mycocin. Thus, mycocin HMK has potential applications in controlling both silage spoilage and yoghurt spoilage caused by yeasts. PMID:10698773

New insights into the capacity of commercial wine yeasts to grow on sparkling wine media. Factor screening for improving wine yeast selection.

PubMed

Borrull, Anna; Poblet, Montse; Rozès, Nicolas

2015-06-01

During the production of sparkling wine, wine yeasts are subjected to many stress factors apart from ethanol, which lead to the need to achieve their acclimation in line with various industrial protocols. In the present work, 44 commercial wine Saccharomyces cerevisiae strains and one laboratory strain (BY4742) were firstly subjected to the influence of increasing concentrations of ethanol to cluster the yeasts using discriminant function analysis. Afterwards, non-inhibitory concentration (NIC) and minimum inhibitory concentration (MIC) were estimated, revealing some differences between 24 of these strains. Meanwhile, this study confirms the negative synergistic effect of low pH with ethanol on the maximum specific growth rate (μmax) and lag phase time. Moreover, a negative effect of increasing levels of glycerol in the growth medium was observed. Interestingly enough, an interactive positive effect was found between cysteine and medium-chain fatty acids (MCFA). While cysteine did not have a really significant effect in comparison to the control, it was able to restore the damage caused by MCFA, making the growth rate of cells recover and even reducing the formation of reactive oxygen species. Adequate culture aeration is also crucial for the composition of the cell fatty acid. The final results showed that few differences were observed between NIC and MIC estimations with respect to cells pre-cultured in the presence or absence of oxygen. Copyright © 2014 Elsevier Ltd. All rights reserved.

Arsenic processing of yeast isolates IIB-As1 & IIB-As2 and production of glutathione under stress conditions.

PubMed

Muneer, Bushra; Lali, Tayyaba; Iqbal, Muhammad J; Shakoori, Farah R; Shakoori, Abdul R

2016-10-01

Four arsenic resistant yeast were isolated from the industrial wastewater. Two strains IIB-As1 and IIB-As2 identified as Candida tropicalis and Saccharomyces cerevisiae, respectively. IIB-As1 and IIB-As2 showed maximum arsenic resistance. IIB-As1 showed maximum growth at 35 °C whereas it was 30 °C for IIB-As2. The yeast isolate showed typical growth curves, but arsenic extended the lag phase. Glutathione plays an important role in metal tolerance. In the present study, As increased the level glutathione and non-protein thiols in yeast isolates. Removal of As from supernatant was analyzed using the atomic absorption spectrophotometer. They removed arsenic from the medium after 72 h of incubation. Both yeast strains efficiently removed arsenic from the industrial effluent when used individually or in consortia. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

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

2013-10-01

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

Effects of Vernonia cinerea less methanol extract on growth and morphogenesis of Candida albicans.

PubMed

Latha, L Yoga; Darah, I; Jain, K; Sasidharan, S

2011-05-01

Vernonia (V.) cinerea Less (Asteraceae) have many therapeutic uses in the practice of traditional medicine. The methanol extract of V cinerea, was screened for antiyeast activity against pathogenic yeast Candida albicans. The antimicrobial activities were studied by using disc diffusion method and broth dilution method. The effect of the extract on the growth profile of the yeast was also examined via time-kill assay. In addition to the fungicidal effects study, microscopic observations using Scanning (SEM) electron microscopy, Transmission (TEM) electron microscopy and light microscopy (LM) were done to determine the major alterations in the microstructure of Candida (C) albicans. The extract showed a favorable antimicrobial activity against C. albicans with a minimum inhibitory concentration (MIC) value of 1.56 mg/mL. Time-kill assay suggested that Vernonia cinerea extract had completely inhibited Candida albicans growth and also exhibited prolonged antiyeast activity. The main abnormalities notes from these microscopic observations were the alterations in morphology and complete collapse of the yeast cells after 36 h of exposure to the extract. The extract of Vernonia cinerea may be an effective agent to treat the Candida albicans infection.

A mitochondria-dependent pathway mediates the apoptosis of GSE-induced yeast.

PubMed

Cao, Sishuo; Xu, Wentao; Zhang, Nan; Wang, Yan; Luo, YunBo; He, Xiaoyun; Huang, Kunlun

2012-01-01

Grapefruit seed extract (GSE), which has powerful anti-fungal activity, can induce apoptosis in S. cerevisiae. The yeast cells underwent apoptosis as determined by testing for apoptotic markers of DNA cleavage and typical chromatin condensation by Terminal Deoxynucleotidyl Transferase-mediated dUTP Nick End Labeling (TUNEL) and 4,6'-diaminidino-2-phenylindole (DAPI) staining and electron microscopy. The changes of ΔΨmt (mitochondrial transmembrane potential) and ROS (reactive oxygen species) indicated that the mitochondria took part in the apoptotic process. Changes in this process detected by metabonomics and proteomics revealed that the yeast cells tenaciously resisted adversity. Proteins related to redox, cellular structure, membrane, energy and DNA repair were significantly increased. In this study, the relative changes in the levels of proteins and metabolites showed the tenacious resistance of yeast cells. However, GSE induced apoptosis in the yeast cells by destruction of the mitochondrial 60 S ribosomal protein, L14-A, and prevented the conversion of pantothenic acid to coenzyme A (CoA). The relationship between the proteins and metabolites was analyzed by orthogonal projections to latent structures (OPLS). We found that the changes of the metabolites and the protein changes had relevant consistency.

A Mitochondria-Dependent Pathway Mediates the Apoptosis of GSE-Induced Yeast

PubMed Central

Cao, Sishuo; Xu, Wentao; Zhang, Nan; Wang, Yan; Luo, YunBo; He, Xiaoyun; Huang, Kunlun

2012-01-01

Grapefruit seed extract (GSE), which has powerful anti-fungal activity, can induce apoptosis in S. cerevisiae. The yeast cells underwent apoptosis as determined by testing for apoptotic markers of DNA cleavage and typical chromatin condensation by Terminal Deoxynucleotidyl Transferase–mediated dUTP Nick End Labeling (TUNEL) and 4,6′-diaminidino-2-phenylindole (DAPI) staining and electron microscopy. The changes of ΔΨmt (mitochondrial transmembrane potential) and ROS (reactive oxygen species) indicated that the mitochondria took part in the apoptotic process. Changes in this process detected by metabonomics and proteomics revealed that the yeast cells tenaciously resisted adversity. Proteins related to redox, cellular structure, membrane, energy and DNA repair were significantly increased. In this study, the relative changes in the levels of proteins and metabolites showed the tenacious resistance of yeast cells. However, GSE induced apoptosis in the yeast cells by destruction of the mitochondrial 60 S ribosomal protein, L14-A, and prevented the conversion of pantothenic acid to coenzyme A (CoA). The relationship between the proteins and metabolites was analyzed by orthogonal projections to latent structures (OPLS). We found that the changes of the metabolites and the protein changes had relevant consistency. PMID:22403727

Integrated approach for selecting efficient Saccharomyces cerevisiae for industrial lignocellulosic fermentations: Importance of yeast chassis linked to process conditions.

PubMed

Costa, Carlos E; Romaní, Aloia; Cunha, Joana T; Johansson, Björn; Domingues, Lucília

2017-03-01

In this work, four robust yeast chassis isolated from industrial environments were engineered with the same xylose metabolic pathway. The recombinant strains were physiologically characterized in synthetic xylose and xylose-glucose medium, on non-detoxified hemicellulosic hydrolysates of fast-growing hardwoods (Eucalyptus and Paulownia) and agricultural residues (corn cob and wheat straw) and on Eucalyptus hydrolysate at different temperatures. Results show that the co-consumption of xylose-glucose was dependent on the yeast background. Moreover, heterogeneous results were obtained among different hydrolysates and temperatures for each individual strain pointing to the importance of designing from the very beginning a tailor-made yeast considering the specific raw material and process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Distribution of yeast-like fungi at a university hospital in Turkey.

PubMed

Ece, Gulfem

2014-12-01

The increased life span has led to application of more invasive procedures for diagnosis and treatment of particularly immunosuppressed individuals. This situation drew more attention to fungal infections due to existence of yeast-like fungi. Candida infections have increased due to transplant in patients, prolonged intensive care unit (ICU) stays, and invasive procedures. Recently, identification of yeast-like fungi as well as antifungal susceptibility test has been gaining more importance. In our study, we aimed to evaluate the distribution of yeast-like fungi strains isolated from blood, urine, wound and respiratory specimens, which were sent from various departments of Izmir University School of Medicine University Hospital. The 262 yeast strains (of 13860 clinical specimens), isolated during 30.05.2012-20.05.2013, which were sent from various departments of Izmir University School of Medicine to Medical Microbiology Laboratory, were included in this study. Blood, wound, respiratory (sputum, tracheal secretion), and urine specimens were cultivated on blood agar and Sabouraud dextrose agar and incubated for 24-48 hours at 37°C. The isolates were cultivated on CHROMagar Candida and Cornmeal Tween 80 medium for identification. Besides, the automatized Vitek version 2.0 system was used for identification of the yeast strains as well as the antifungal susceptibility of blood culture strains. A total of 262 strains, isolated from the Anesthesiology and Reanimation Unit, as well as from the departments of Hematology, Urology, Infectious Diseases, Gynecology and Obstetrics, and Ear Nose and Throat, were included in this study. The most common isolated yeast-like species was Candida albicans. C. parapsilosis was the most common yeast-like fungus isolated from blood cultures. All the blood culture strains were susceptible to amphotericin B, flucytosine, fluconazole and voriconazole. Candida strains isolated from newborns, elderly patients, and intensive care patients

Polyurethane foam loaded with sodium dodecylsulfate for the extraction of 'quat' pesticides from aqueous medium: Optimization of loading conditions.

PubMed

Vinhal, Jonas O; Lima, Claudio F; Cassella, Ricardo J

2016-09-01

The cationic herbicides paraquat, diquat and difenzoquat are largely used in different cultures worldwide. With this, there is an intrinsic risk of environmental contamination when these herbicides achieve natural waters. The goal of this work was to propose a novel and low-cost sorbent for the removal of the cited herbicides from aqueous medium. The proposed sorbent was prepared by loading polyurethane foam with sodium dodecylsulfate. The influence of several parameters (SDS concentration, HCl concentration and shaking time) on the loading process was investigated. The results obtained in this work demonstrated that all studied variables influenced the loading process, having significant effect on the extraction efficiency of the resulted PUF-SDS. At optimized conditions, the PUF was loaded by shaking 200mg of crushed foam with 200mL of a solution containing 5.0×10(-3)molL(-1) SDS and 0.25molL(-1) HCl, for 30min. The obtained PUF-SDS was efficient for removing the three herbicides from aqueous medium, achieving extraction percentages higher than 90%. The sorption process followed a pseudo second-order kinetics, which presented excellent predictive capacity of the amount of herbicide retained with time. Copyright © 2016 Elsevier Inc. All rights reserved.

Tris-sucrose buffer system: a new specially designed medium for extracellular invertase production by immobilized cells of isolated yeast Cryptococcus laurentii MT-61.

PubMed

Aydogan, Mehmet Nuri; Taskin, Mesut; Canli, Ozden; Arslan, Nazli Pinar; Ortucu, Serkan

2014-01-01

The aims of the present study were to isolate new yeasts with high extracellular (exo) invertase activity and to investigate the usability of buffer systems as invertase production media by immobilized yeast cells. Among 70 yeast isolates, Cryptococcus laurentii MT-61 had the highest exo-invertase activity. Immobilization of yeast cells was performed using sodium alginate. Higher exo-invertase activity for immobilized cells was achieved in tris-sucrose buffer system (TSBS) compared to sodium acetate buffer system and potassium phosphate buffer system. TSBS was prepared by dissolving 30 g of sucrose in 1 L of tris buffer solution. The optimum pH, temperature, and incubation time for invertase production with immobilized cells were determined as 8.0, 35 °C and 36 h in TSBS, respectively. Under optimized conditions, maximum exo-invertase activity was found to be 28.4 U/mL in sterile and nonsterile TSBS. Immobilized cells could be reused in 14 and 12 successive cycles in sterile and nonsterile TSBS without any loss in the maximum invertase activity, respectively. This is the first report which showed that immobilized microbial cells could be used as a biocatalyst for exo-invertase production in buffer system. As an additional contribution, a new yeast strain with high invertase activity was isolated.

Enzymes in Glycolysis and the Citric Acid Cycle in the Yeast and Mycelial Forms of Paracoccidioides brasiliensis

PubMed Central

Kanetsuna, Fuminori; Carbonell, Luis M.

1966-01-01

Kanetsuna, Fuminori (Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela), and Luis M. Carbonell. Enzymes in glycolysis and the citric acid cycle in the yeast and mycelial forms of Paracoccidioides brasiliensis. J. Bacteriol. 92:1315–1320. 1966.—Enzymatic activities in glycolysis, the hexose monophosphate shunt, and the citric acid cycle in cell-free extracts of the yeast and mycelial forms of Paracoccidioides brasiliensis were examined comparatively. Both forms have the enzymes of these pathways. Activities of glucose-6-phosphate dehydrogenase and malic dehydrogenase of the mycelial form were higher than those of the yeast form. Another 15 enzymatic activities of the mycelial form were lower than those of the yeast form. The activity of glyceraldehyde-3-phosphate dehydrogenase showed the most marked difference between the two forms, its activity in the mycelial form being about 20% of that in the yeast form. PMID:5924267

Gateway Vectors for Efficient Artificial Gene Assembly In Vitro and Expression in Yeast Saccharomyces cerevisiae

PubMed Central

Giuraniuc, Claudiu V.; MacPherson, Murray; Saka, Yasushi

2013-01-01

Construction of synthetic genetic networks requires the assembly of DNA fragments encoding functional biological parts in a defined order. Yet this may become a time-consuming procedure. To address this technical bottleneck, we have created a series of Gateway shuttle vectors and an integration vector, which facilitate the assembly of artificial genes and their expression in the budding yeast Saccharomyces cerevisiae. Our method enables the rapid construction of an artificial gene from a promoter and an open reading frame (ORF) cassette by one-step recombination reaction in vitro. Furthermore, the plasmid thus created can readily be introduced into yeast cells to test the assembled gene’s functionality. As flexible regulatory components of a synthetic genetic network, we also created new versions of the tetracycline-regulated transactivators tTA and rtTA by fusing them to the auxin-inducible degron (AID). Using our gene assembly approach, we made yeast expression vectors of these engineered transactivators, AIDtTA and AIDrtTA and then tested their functions in yeast. We showed that these factors can be regulated by doxycycline and degraded rapidly after addition of auxin to the medium. Taken together, the method for combinatorial gene assembly described here is versatile and would be a valuable tool for yeast synthetic biology. PMID:23675537

[Fluconazole and itraconazole susceptibility testing with clinical yeast isolates and algae of the genus Prototheca by means of the Etest].

PubMed

Blaschke-Hellmessen, R

1996-01-01

Preliminary own results suggest, that the Etest (produced by AB BIODISK, Solna, Sweden) performed on casitone medium meets the requirements of a routine test of yeast susceptibility to fluconazole and itraconazole. Testing of 46 clinical yeast isolates, of 5 strains of Exophiala dermatitidis and 4 strains of algae of the genus Prototheca revealed species-, genus- and strain-specific variations of the susceptibility to fluconazole and itraconazole. Candida glabrata was less susceptible to both triazoles than the other Candida species with exception of Candida krusei. Exophiala dermatitidis was highly susceptible to itraconazole. Prototheca wickerhamii and P. zopfii were resistant to both triazoles. Casitone medium is most appropriate for the determination of susceptibility to fluconazole and itraconazole by the Etest. The results of the Etest were comparable with those of a breakpoint test (microdilution method).

Effects of alkylresorcinols on volume and structure of yeast-leavened bread.

PubMed

Andersson, Annica Am; Landberg, Rikard; Söderman, Thomas; Hedkvist, Sofie; Katina, Kati; Juvonen, Riikka; Holopainen, Ulla; Lehtinen, Pekka; Aman, Per

2011-01-30

Alkylresorcinols (AR) are amphiphilic phenolic compounds found in high amounts in wheat, durum wheat and rye, with different homologue composition for each cereal. The effect of different amounts of added AR from these cereals on bread volume, height, porosity and microstructure was studied. Breads with added rye bran (with high levels of AR) or acetone-extracted rye bran (with low levels of AR) were also baked, as well as breads with finely milled forms of each of these brans. Breads with high amounts of added AR, irrespective of AR homologue composition, had a lower volume, a more compact structure and an adverse microstructure compared with breads with no or low levels of added AR. AR were also shown to inhibit the activity of baker's yeast. There was no difference in bread volume and porosity between bread baked with rye bran and acetone-extracted rye bran or with brans of different particle size. Irrespective of homologue composition, AR had a negative effect on wheat bread properties when added in high amounts as purified extracts from wheat, durum wheat and rye. Natural levels of AR in rye bran, however, did not affect the volume and porosity of yeast-leavened wheat breads. 2010 Society of Chemical Industry.

Heat shock, visible light or high calcium augment the cytotoxic effects of Ailanthus altissima (Swingle) leaf extracts against Saccharomyces cerevisiae cells.

PubMed

Popa, Claudia Valentina; Lungu, Liliana; Cristache, Ligia Florentina; Ciuculescu, Crinu; Danet, Andrei Florin; Farcasanu, Ileana Cornelia

2015-01-01

To gain new insight into the antimicrobial potential of Ailanthus altissima Swingle, ethanol leaf extracts were evaluated for the antifungal effects against the model yeast Saccharomyces cerevisae. The extracts inhibited the yeast growth in a dose-dependent manner, and this effect could be augmented by heat shock, exposure to visible light or exposure to high concentrations of Ca(2+). Using transgenic yeast cells expressing the Ca(2+)-dependent photoprotein, aequorin, it was found that the leaf extracts induced cytosolic Ca(2+) elevation. Experiments on yeast mutants with defects in Ca(2+) transport demonstrated that the cytotoxicity of the A. altissima leaf extracts (AaLEs) was mediated by transient pulses of Ca(2+) ions which were released into the cytosol predominantly from the vacuole. The investigation of the antifungal synergies involving AaLEs may contribute to the development of optimal and safe combination therapies for the treatment of drug-resistant fungal infections.

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

PubMed

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

2012-04-01

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

Effect of wine yeast monoculture practice on the biodiversity of non-Saccharomyces yeasts.

PubMed

Ganga, M A; Martínez, C

2004-01-01

The objective of this work was to study the effect of the use of Saccharomyces cerevisiae monocultures over the biodiversity of non-Saccharomyces yeasts in wine-producing areas in Chile. Microvinifications were carried out with grape musts of two areas. In one of them, the fermentation is carried out mainly in a spontaneous manner, whereas in the other the musts are inoculated with commercial yeasts. The isolated yeasts were identified by the internal transcribed (ITS)/restriction fragment length polymorphism technique. In the industrial production area less variability of yeast genera was observed as compared with the traditional area, an observation that is greatest at the end of the fermentation. Furthermore, a study of the production of extracellular enzymes was done. The majority of the yeasts showed at least one of the activities assayed with the exception of beta-glycosidase. The results suggest that in the industrialized area the diversity of yeasts is less in the traditional area. Likewise, the potentiality of the non-Saccharomyces yeasts as enzyme producers with industrial interest has been confirmed. This study shows the negative effect of the use of monocultures over the biodiversity of yeasts in wine-producing regions.

Occurrence of yeasts in psittacines droppings from captive birds in Italy.

PubMed

Mancianti, Francesca; Nardoni, Simona; Ceccherelli, Renato

2002-01-01

Three-hundred twenty five droppings from parrots raised in the premises of 4 breeders and in several private households were cultured for yeasts. One-hundred sixty droppings (49.2%) resulted positive. From these specimens 212 isolates belonging to 27 different species were obtained. Mainly Candida species such as C. albicans, C. catenulata, C. curvata, C. famata, C. glabrata, C. guilliermondi, C. holmii, C. intermedia, C. krusei, C. lambica, C. lusitaniae, C. membranaefaciens, C. parapsilosis, C. pelliculosa, C. sake and C. valida were isolated. Debarvomyces marama, D. polymorphus, Geotrichum sp., Pichia etchelsii, P. ohmeri, Rhodotorula glutinis, R. rubra, Rhodotorula sp., Saccharomyces cerevisiae, S. kluyiveri and Zygosaccharomyces sp. were also obtained. Dark colonies on Staib medium were never observed. The psittacine birds apparently serve as carriers for several Candida species or their perfect states and to a lesser extent for other opportunistic yeasts such as Rhodotorula, Trichosporon and Saccharomyces spp., which are considered part of the transient microbiota of the gastrointestinal tract. The most striking finding was the absence of Cryptococcus spp. among the isolates. The present survey confirms the role of pet birds in carrying potential zoonotic yeasts.

Fermentation of soluble cello-oligosaccharides by yeasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lastick, S.M.; Spindler, D.D.; Grohmann, K.

1983-02-01

Yeast strains that ferment cellobiose were examined with respect to fermentation on soluble cellodextrin preparations. Hydrolysis of the fermentation products was followed using thin layer chromatography. Candida and Brettanomyces sp. hydrolyze cellobiose and, at a much lower rate, cellotriose, indicating the presence of ..beta..-glucosidase (EC 3.2.1.21) activity. Enzyme assays conducted on B. clausenii fermentations indicated that the ..beta..-glucosidase remained cell-associated during fermentation. Torulopsis sp. hydrolyzed all of the cello-oligo-saccharides, indicating exoglucanase (EC 3.2.1.91) activity. The exogluconanase, a glycoprotein with an apparent molecular weight of 8.4 x 10/sup 4/ daltons, is exported into the culture medium.

SOLVENT EXTRACTION PROCESS

DOEpatents

Jonke, A.A.

1957-10-01

In improved solvent extraction process is described for the extraction of metal values from highly dilute aqueous solutions. The process comprises contacting an aqueous solution with an organic substantially water-immiscible solvent, whereby metal values are taken up by a solvent extract phase; scrubbing the solvent extract phase with an aqueous scrubbing solution; separating an aqueous solution from the scrubbed solvent extract phase; and contacting the scrubbed solvent phase with an aqueous medium whereby the extracted metal values are removed from the solvent phase and taken up by said medium to form a strip solution containing said metal values, the aqueous scrubbing solution being a mixture of strip solution and an aqueous solution which contains mineral acids anions and is free of the metal values. The process is particularly effective for purifying uranium, where one starts with impure aqueous uranyl nitrate, extracts with tributyl phosphate dissolved in carbon tetrachloride, scrubs with aqueous nitric acid and employs water to strip the uranium from the scrubbed organic phase.

Reduction of Mercury to the Elemental State by a Yeast

PubMed Central

Brunker, Richard L.; Bott, Thomas L.

1974-01-01

A yeast of the genus Cryptococcus has been isolated from a stream and was shown to be capable of reducing mercury to the elemental state. The organism grows in Wickerham broth supplemented with high concentrations of mercury (II) chloride (180 mg of mercury per liter) and will metabolize [14C]glucose in this medium as do cells in the absence of mercury. Mercury was associated with the cell wall and membrane, and in vacuoles within the cytoplasm. Images PMID:4364461

Production of baker's yeast using date juice.

PubMed

Beiroti, A; Hosseini, S N

2007-07-01

Baker's yeast is an important additive among the products which improves bread quality and for present time is being produced in different countries by batch, fed batch or continuous cultures. Saccharomyces cerevisiae is used in fermentation of starch in dough, giving a favourable taste and produces a variety of vitamins and proteins. The main ingredient in yeast production is carbon source such as beet molasses, cane molasses, and so on. Since beet molasses has other major function as in high yield alcohol production and also due to the bioenvironmental issues and related wastewater treatment, the use of other carbohydrate sources may be considered. One of these carbohydrate sources is date which is wasted a great deal annually in this country (Iran) . In this study, the capability of date to act as a suitable carbon sources was investigated. The waste date turned into juice and consequently production and growth rate of Sacchromyces cervisiae were studied with this juice. A maximum possible yield of 50% was obtained by the optimum medium (P3), at pH 3.4, 30 degrees C, 1.4 vvm aeration rate and agitation of 500 r/min.

Raman spectroscopy to monitor the effects of temperature regime and medium composition on micro-organism growth

NASA Astrophysics Data System (ADS)

Samek, O.; Haroniková, A.; Ježek, J.; Bernatová, S.; Márová, I.; Breierová, E.; Šerý, M.; Šiler, M.; Zemánek, P.

2016-12-01

A biomass of yeast strains has been studied using Raman spectroscopy due to their potential applications in the field of biofuel generation, food industry and biotechnological applications. In order to utilize biomass for efficient industrial/biotechnological production, the optimal cultivation parameters have to be determined which in turn lead to high production of desired substances such as oil, carotenoids, and pigments in the selected cell line of yeast. Therefore, we focused on different cultivation conditions (the effects of temperature regime and medium composition) and their influence on microorganisms growth and metabolic changes.

Influence of Culture Media on the Radiation Resistance of Micrococcus radiodurans

PubMed Central

Krabbenhoft, K. L.; Anderson, A. W.; Elliker, P. R.

1967-01-01

The addition of NZ-case (a tryptic digest of casein) to a growth medium (PC) consisting of tryptone, glucose, and yeast extract caused a significant decrease in γ radiation resistance of Micrococcus radiodurans. The level of radiation resistance was inversely related to the concentration of NZ-case. The ld50 for this organism was approximately 700 krad when grown in tryptone, glucose, yeast extract, and dl-methionine (TGYM) broth, but it was approximately one-half as resistant when grown in a PC medium containing 0.5% NZ-case (PCNZ). The resistance to ultraviolet light was also reduced. Cultures transferred from PCNZ to TGYM media regained the high level of resistance. Images Fig. 2 Fig. 3 PMID:5340165

CPTC and NIST-sponsored Yeast Reference Material Now Publicly Available | Office of Cancer Clinical Proteomics Research

Cancer.gov

The yeast protein extract (RM8323) developed by National Institute of Standards and Technology (NIST) under the auspices of NCI's CPTC initiative is currently available to the public at https://www-s.nist.gov/srmors/view_detail.cfm?srm=8323. The yeast proteome offers researchers a unique biological reference material. RM8323 is the most extensively characterized complex biological proteome and the only one associated with several large-scale studies to estimate protein abundance across a wide concentration range.

Yeast cell differentiation: Lessons from pathogenic and non-pathogenic yeasts.

PubMed

Palková, Zdena; Váchová, Libuše

2016-09-01

Yeasts, historically considered to be single-cell organisms, are able to activate different differentiation processes. Individual yeast cells can change their life-styles by processes of phenotypic switching such as the switch from yeast-shaped cells to filamentous cells (pseudohyphae or true hyphae) and the transition among opaque, white and gray cell-types. Yeasts can also create organized multicellular structures such as colonies and biofilms, and the latter are often observed as contaminants on surfaces in industry and medical care and are formed during infections of the human body. Multicellular structures are formed mostly of stationary-phase or slow-growing cells that diversify into specific cell subpopulations that have unique metabolic properties and can fulfill specific tasks. In addition to the development of multiple protective mechanisms, processes of metabolic reprogramming that reflect a changed environment help differentiated individual cells and/or community cell constituents to survive harmful environmental attacks and/or to escape the host immune system. This review aims to provide an overview of differentiation processes so far identified in individual yeast cells as well as in multicellular communities of yeast pathogens of the Candida and Cryptococcus spp. and the Candida albicans close relative, Saccharomyces cerevisiae. Molecular mechanisms and extracellular signals potentially involved in differentiation processes are also briefly mentioned. Copyright © 2016 Elsevier Ltd. All rights reserved.

Issues in identifying germ tube positive yeasts by conventional methods.

PubMed

Yazdanpanah, Atta; Khaithir, Tzar Mohd Nizam

2014-01-01

Candida speciation is vital for epidemiology and management of candidiasis. Nonmolecular conventional methods often fail to identify closely related germ tube positive yeasts from clinical specimens. The present study was conducted to identify these yeasts and to highlight issues in conventional versus molecular methods of identification. A total of 98 germ tube positive yeasts from high vaginal swabs were studied over a 12-month period. Isolates were examined with various methods including growth at 42 °C and 45 °C on Sabouraud dextrose agar (SDA), color development on CHROMagar Candida medium, chlamydospore production on corn meal agar at 25 °C, carbohydrate assimilation using ID 32C system, and polymerase chain reaction using a single pair of primers targeting the hyphal wall protein 1 (Hwp1) gene. Of all the isolates studied, 97 were molecularly confirmed as C. albicans and one isolate was identified as C. dubliniensis. No C. africana was detected in this study. The molecular method used in our study was an accurate and useful tool for discriminating C. albicans, C. dubliniensis, and C. africana. The conventional methods, however, were less accurate and riddled with many issues that will be discussed in further details. © 2013 Wiley Periodicals, Inc.

L-arabinose fermenting yeast

DOEpatents

Zhang, Min; Singh, Arjun; Knoshaug, Eric; Franden, Mary Ann; Jarvis, Eric; Suominen, Pirkko

2010-12-07

An L-arabinose utilizing yeast strain is provided for the production of ethanol by introducing and expressing bacterial araA, araB and araD genes. L-arabinose transporters are also introduced into the yeast to enhance the uptake of arabinose. The yeast carries additional genomic mutations enabling it to consume L-arabinose, even as the only carbon source, and to produce ethanol. Methods of producing ethanol include utilizing these modified yeast strains. ##STR00001##

Nitrile Metabolizing Yeasts

NASA Astrophysics Data System (ADS)

Bhalla, Tek Chand; Sharma, Monica; Sharma, Nitya Nand

Nitriles and amides are widely distributed in the biotic and abiotic components of our ecosystem. Nitrile form an important group of organic compounds which find their applications in the synthesis of a large number of compounds used as/in pharmaceutical, cosmetics, plastics, dyes, etc>. Nitriles are mainly hydro-lyzed to corresponding amide/acid in organic chemistry. Industrial and agricultural activities have also lead to release of nitriles and amides into the environment and some of them pose threat to human health. Biocatalysis and biotransformations are increasingly replacing chemical routes of synthesis in organic chemistry as a part of ‘green chemistry’. Nitrile metabolizing organisms or enzymes thus has assumed greater significance in all these years to convert nitriles to amides/ acids. The nitrile metabolizing enzymes are widely present in bacteria, fungi and yeasts. Yeasts metabolize nitriles through nitrilase and/or nitrile hydratase and amidase enzymes. Only few yeasts have been reported to possess aldoxime dehydratase. More than sixty nitrile metabolizing yeast strains have been hither to isolated from cyanide treatment bioreactor, fermented foods and soil. Most of the yeasts contain nitrile hydratase-amidase system for metabolizing nitriles. Transformations of nitriles to amides/acids have been carried out with free and immobilized yeast cells. The nitrilases of Torulopsis candida>and Exophiala oligosperma>R1 are enantioselec-tive and regiospecific respectively. Geotrichum>sp. JR1 grows in the presence of 2M acetonitrile and may have potential for application in bioremediation of nitrile contaminated soil/water. The nitrilase of E. oligosperma>R1 being active at low pH (3-6) has shown promise for the hydroxy acids. Immobilized yeast cells hydrolyze some additional nitriles in comparison to free cells. It is expected that more focus in future will be on purification, characterization, cloning, expression and immobilization of nitrile metabolizing

Outward electron transfer by Saccharomyces cerevisiae monitored with a bi-cathodic microbial fuel cell-type activity sensor.

PubMed

Ducommun, Raphaël; Favre, Marie-France; Carrard, Delphine; Fischer, Fabian

2010-03-01

A Janus head-like bi-cathodic microbial fuel cell was constructed to monitor the electron transfer from Saccharomyces cerevisiae to a woven carbon anode. The experiments were conducted during an ethanol cultivation of 170 g/l glucose in the presence and absence of yeast-peptone medium. First, using a basic fuel-cell type activity sensor, it was shown that yeast-peptone medium contains electroactive compounds. For this purpose, 1% solutions of soy peptone and yeast extract were subjected to oxidative conditions, using a microbial fuel cell set-up corresponding to a typical galvanic cell, consisting of culture medium in the anodic half-cell and 0.5 M K(3)Fe(CN)(6) in the cathodic half-cell. Second, using a bi-cathodic microbial fuel cell, it was shown that electrons were transferred from yeast cells to the carbon anode. The participation of electroactive compounds in the electron transport was separated as background current. This result was verified by applying medium-free conditions, where only glucose was fed, confirming that electrons are transferred from yeast cells to the woven carbon anode. Knowledge about the electron transfer through the cell membrane is of importance in amperometric online monitoring of yeast fermentations and for electricity production with microbial fuel cells. Copyright (c) 2009 John Wiley & Sons, Ltd.

Enhancement of docosahexaenoic acid (DHA) production from Schizochytrium sp. S31 using different growth medium conditions.

PubMed

Sahin, Deniz; Tas, Ezgi; Altindag, Ulkü Hüma

2018-01-24

Schizochytrium species is one of the most studied microalgae for production of docosahexaenoic acid (DHA) which is an omega-3 fatty acid with positive effects for human health. However, high cost and low yield in production phase makes optimization of cultivation process inevitable. We focus on the optimization of DHA production using Schizochytrium sp. using different media supplements; glucose, fructose and glycerol as carbon variants, proteose peptone and tryptone as nitrogen variants. The highest biomass (5.61 g/L) and total fatty acid yield (1.74 g/L) were obtained in proteose peptone medium which was used as the alternative nitrogen source instead of yeast extract. The highest DHA yield (0.40 g/L) was achieved with glycerol as the carbon source although it had the second lowest biomass production after ethanol containing medium. Ethanol, as an alternative carbon source and a precursor for acetyl-CoA, increased DHA percentage in total lipid content from 29.94 to 40.04% but decreasing the biomass drastically. Considering different carbon and nitrogen sources during cultivation of Schizochytrium sp. will improve DHA production. Combination of proteose peptone and glycerol as nitrogen and carbon sources, respectively, and addition of ethanol with a proper timing will be useful to have higher DHA yield.

Functional Conservation of Coenzyme Q Biosynthetic Genes among Yeasts, Plants, and Humans

PubMed Central

Hayashi, Kazuhiro; Ogiyama, Yuki; Yokomi, Kazumasa; Nakagawa, Tsuyoshi; Kaino, Tomohiro; Kawamukai, Makoto

2014-01-01

Coenzyme Q (CoQ) is an essential factor for aerobic growth and oxidative phosphorylation in the electron transport system. The biosynthetic pathway for CoQ has been proposed mainly from biochemical and genetic analyses of Escherichia coli and Saccharomyces cerevisiae; however, the biosynthetic pathway in higher eukaryotes has been explored in only a limited number of studies. We previously reported the roles of several genes involved in CoQ synthesis in the fission yeast Schizosaccharomyces pombe. Here, we expand these findings by identifying ten genes (dps1, dlp1, ppt1, and coq3–9) that are required for CoQ synthesis. CoQ10-deficient S. pombe coq deletion strains were generated and characterized. All mutant fission yeast strains were sensitive to oxidative stress, produced a large amount of sulfide, required an antioxidant to grow on minimal medium, and did not survive at the stationary phase. To compare the biosynthetic pathway of CoQ in fission yeast with that in higher eukaryotes, the ability of CoQ biosynthetic genes from humans and plants (Arabidopsis thaliana) to functionally complement the S. pombe coq deletion strains was determined. With the exception of COQ9, expression of all other human and plant COQ genes recovered CoQ10 production by the fission yeast coq deletion strains, although the addition of a mitochondrial targeting sequence was required for human COQ3 and COQ7, as well as A. thaliana COQ6. In summary, this study describes the functional conservation of CoQ biosynthetic genes between yeasts, humans, and plants. PMID:24911838

New culture medium for the presumptive identificaion of Candida albicans and Cryptococcus neoformans.

PubMed Central

Fleming, W H; Hopkins, J M; Land, G A

1977-01-01

A new medium composed of Tween 80, oxgall, caffeic acid, and Davis agar (TOC) that provides for the rapid presumptive identification of Candida albicans and Cryptococcus neoformans is described herein. C. albicans is differentiated from other yeasts by the sequential production of germ tubes and chlamydospores. In a comparison with cormeal agar control plates, there was an increase of chlamydospore-forming strains of C. albicans (97.1% versus 87.2%) and a decrease in the time required for chlamydospore formation (24 h versus 48 h). C. neoformans produced a brown pigment of TOC, which is specific for its identification, thus differentiating it from the other yeasts. A comparison of 24-h pigment production by C. neoformans on TOC with that of birdseed agar showed a dark, coffee brown color in the former cultures and a light brown color in the latter. The change in pigmentation of C. neoformans, as well as morphological changes in C. albicans, can be induced within 3 to 12 h and in not more than 24 h on the TOC medium. Images PMID:321472

Impact of osmotic stress and ethanol inhibition in yeast cells on process oscillation associated with continuous very-high-gravity ethanol fermentation

PubMed Central

2013-01-01

Background VHG fermentation is a promising process engineering strategy aiming at improving ethanol titer, and thus saving energy consumption for ethanol distillation and distillage treatment. However, sustained process oscillation was observed during continuous VHG ethanol fermentation, which significantly affected ethanol fermentation performance of the system. Results Sustained process oscillation was investigated in continuous VHG ethanol fermentation, and stresses exerted on yeast cells by osmotic pressure from unfermented sugars and ethanol inhibition developed within the fermentation system were postulated to be major factors triggering this phenomenon. In this article, steady state was established for continuous ethanol fermentation with LG medium containing 120 g/L glucose, and then 160 g/L non-fermentable xylose was supplemented into the LG medium to simulate the osmotic stress on yeast cells under the VHG fermentation condition, but the fermentation process was still at steady state, indicating that the impact of osmotic stress on yeast cells was not the main reason for the process oscillation. However, when 30 g/L ethanol was supplemented into the LG medium to simulate the ethanol inhibition in yeast cells under the VHG fermentation condition, process oscillation was triggered, which was augmented with extended oscillation period and exaggerated oscillation amplitude as ethanol supplementation was increased to 50 g/L, but the process oscillation was gradually attenuated when the ethanol supplementations were stopped, and the steady state was restored. Furthermore, gas stripping was incorporated into the continuous VHG fermentation system to in situ remove ethanol produced by Saccharomyces cerevisiae, and the process oscillation was also attenuated, but restored after the gas stripping was interrupted. Conclusions Experimental results indicated that ethanol inhibition rather than osmotic stress on yeast cells is one of the main factors triggering the

[Evaluation of a new medium, eggplant (Solanum melongena) agar as a screening medium for Cryptococcus neoformans in environmental samples].

PubMed

Sengul, Mustafa; Ergin, Cağrı; Kartal, Tuğba

2014-04-01

Cryptococcus neofomans is an encapsulated yeast-like fungus that causes life-threatening infections, especially in immunosuppresive patients. C.neoformans infection is believed to be acquired via inhalation of aerosolized particles from the environment. Avian guano, decaying tree hollows and soil are the related known environmental niches. Brown pigmented yeast growth from the precursors in growth media is an important step for the identification and isolation of C.neoformans. Seeds of plants in nature are preferred owing to easy accessibility and low costs for the preparation of such media. Guizotia abysinicca (Niger seed) as Staib agar, Helianthus annus (Sunflower) as Pal's medium, Brassica nigra (Mustard) agar, tobacco agar, Mucuna pruriens (Velvet bean) seed agar, Perilla frutescens (Beefsteak plant) seed agar, Rubus fruticosus (Blackberry) agar and ground red hot pepper agar are pigment-based selective media for the differentiation of C.neoformans. The aim of this study was to observe the pigment production of C.neoformans in a new medium based on eggplant (Solanum melongena) and also to compare its performance with the simplified Staib, Pal's and tobacco agar for isolation from the environment. Three different eggplant-based medium (S.melongena Melanzaza viserba, S.melongena Pinstripe F1 and S.ovigerum Ivory F1) were included in the study. Pigment-forming eggplant medium, simplified Staib agar, Pal's agar and tobacco agar were used for the cultivation of the environmental swabbed samples from 19 Eucalyptus camaldulensis trunk hollows in continuous colonization region. While pigment formation were observed with S.melongena Melanzaza viserba and S.melongena Pinstripe F1 containing media, S.ovigerum Ivory F1 medium was found to be non-reactive. In colonization area (Gökova-Akyaka, Turkey), 11 (57.9%) out of 19 E.camaldulensis samples were positive with simplified Staib agar, Pal's agar and eggplant agar while 10 (52.6%) of them are positive with tobacco agar. C

Genome dynamics and evolution in yeasts: A long-term yeast-bacteria competition experiment

PubMed Central

Katz, Michael; Knecht, Wolfgang; Compagno, Concetta; Piškur, Jure

2018-01-01

There is an enormous genetic diversity evident in modern yeasts, but our understanding of the ecological basis of such diversifications in nature remains at best fragmented so far. Here we report a long-term experiment mimicking a primordial competitive environment, in which yeast and bacteria co-exist and compete against each other. Eighteen yeasts covering a wide phylogenetic background spanning approximately 250 million years of evolutionary history were used to establish independent evolution lines for at most 130 passages. Our collection of hundreds of modified strains generated through such a rare two-species cross-kingdom competition experiment re-created the appearance of large-scale genomic rearrangements and altered phenotypes important in the diversification history of yeasts. At the same time, the methodology employed in this evolutionary study would also be a non-gene-technological method of reprogramming yeast genomes and then selecting yeast strains with desired traits. Cross-kingdom competition may therefore be a method of significant value to generate industrially useful yeast strains with new metabolic traits. PMID:29624585

Volatile compounds in whole meal bread crust: The effects of yeast level and fermentation temperature.

PubMed

Nor Qhairul Izzreen, M N; Hansen, Se S; Petersen, Mikael A

2016-11-01

The influence of fermentation temperatures (8°C, 16°C, and 32°C) and yeast levels (2%, 4%, and 6% of the flour) on the formation of volatile compounds in the crust of whole meal wheat bread was investigated. The fermentation times were regulated to optimum bread height for each treatment. The volatile compounds were extracted by dynamic headspace extraction and analyzed by gas chromatography-mass spectrometry. The results were evaluated using multivariate data analysis and ANOVA. In all crust samples 28 volatile compounds out of 58 compounds were identified and the other 30 compounds were tentatively identified. Higher fermentation temperatures promoted the formation of Maillard reaction products 3-methyl-1-butanol, pyrazine, 2-ethylpyrazine, 2-ethyl-3-methylpyrazine, 2-vinylpyrazine, 3-hydroxy-2-butanone, 3-(methylsulfanyl)-propanal, and 5-methyl-2-furancarboxaldehyde whereas at lower temperature (8°C) the formation of 2- and 3-methylbutanal was favored. Higher levels of yeast promoted the formation of 3-methyl-1-butanol, 2-methyl-1-propanol and 3-(methylsulfanyl)-propanal, whereas hexanal was promoted in the crust fermented with lower yeast level. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nectar-living yeasts of a tropical host plant community: diversity and effects on community-wide floral nectar traits

PubMed Central

2017-01-01

We characterize the diversity of nectar-living yeasts of a tropical host plant community at different hierarchical sampling levels, measure the associations between yeasts and nectariferous plants, and measure the effect of yeasts on nectar traits. Using a series of hierarchically nested sampling units, we extracted nectar from an assemblage of host plants that were representative of the diversity of life forms, flower shapes, and pollinator types in the tropical area of Yucatan, Mexico. Yeasts were isolated from single nectar samples; their DNA was identified, the yeast cell density was estimated, and the sugar composition and concentration of nectar were quantified using HPLC. In contrast to previous studies from temperate regions, the diversity of nectar-living yeasts in the plant community was characterized by a relatively high number of equally common species with low dominance. Analyses predict highly diverse nectar yeast communities in a relatively narrow range of tropical vegetation, suggesting that the diversity of yeasts will increase as the number of sampling units increases at the level of the species, genera, and botanical families of the hosts. Significant associations between specific yeast species and host plants were also detected; the interaction between yeasts and host plants impacted the effect of yeast cell density on nectar sugars. This study provides an overall picture of the diversity of nectar-living yeasts in tropical host plants and suggests that the key factor that affects the community-wide patterns of nectar traits is not nectar chemistry, but rather the type of yeasts interacting with host plants. PMID:28717591

Filtration, haze and foam characteristics of fermented wort mediated by yeast strain.

PubMed

Douglas, P; Meneses, F J; Jiranek, V

2006-01-01

To investigate the influence of the choice of yeast strain on the haze, shelf life, filterability and foam quality characteristics of fermented products. Twelve strains were used to ferment a chemically defined wort and hopped ale or stout wort. Fermented products were assessed for foam using the Rudin apparatus, and filterability and haze characteristics using the European Brewing Convention methods, to reveal differences in these parameters as a consequence of the choice of yeast strain and growth medium. Under the conditions used, the choice of strain of Saccharomyces cerevisiae effecting the primary fermentation has an impact on all of the parameters investigated, most notably when the fermentation medium is devoid of macromolecular material. The filtration of fermented products has a large cost implication for many brewers and wine makers, and the haze of the resulting filtrate is a key quality criterion. Also of importance to the quality of beer and some wines is the foaming and head retention of these beverages. The foam characteristics, filterability and potential for haze formation in a fermented product have long been known to be dependant on the raw materials used, as well as other production parameters. The choice of Saccharomyces cerevisiae strain used to ferment has itself been shown here to influence these parameters.

Effects of yeast and bran on phytate degradation and minerals in rice bread.

PubMed

Kadan, R S; Phillippy, B Q

2007-05-01

Rice bread is a potential alternative to wheat bread for gluten-sensitive individuals. Incorporation of rice bran into bread made from white rice flour adds flavor but also phytic acid, which can reduce the bioavailability of minerals. Breads with varied amounts of defatted bran and yeast were prepared to determine their effects on the phytate and mineral contents of the bread. A completely randomized factorial design was used with bran levels of 3.7%, 7.3%, and 10.5% of the dry ingredients and yeast levels of 1.6%, 3.2%, and 4.7%. Increasing the amount of bran decreased the phytate degradation from 42% at the lowest level of bran to 10% at the highest, and the amount of yeast had no significant effect. The bran contributed substantial amounts of magnesium, iron, and zinc. Breads with the lowest level of bran had phytate-to-zinc molar ratios between 5 and 10, which suggest medium zinc bioavailability. Rice bread is a tasty and nutritious food that is a good dietary source of minerals for people who cannot tolerate wheat bread.

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

PubMed

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.

Lindane degradation by Candida VITJzN04, a newly isolated yeast strain from contaminated soil: kinetic study, enzyme analysis and biodegradation pathway.

PubMed

Salam, Jaseetha Abdul; Das, Nilanjana

2014-04-01

A new yeast strain was isolated from sugarcane cultivation field which was able to utilize lindane as sole carbon source for growth in mineral medium. The yeast was identified and named as Candida sp. VITJzN04 based on a polyphasic approach using morphological, biochemical and 18S rDNA, D1/D2 and ITS sequence analysis. The isolated yeast strain efficiently degraded 600 mg L⁻¹ of lindane within 6 days in mineral medium under the optimal conditions (pH 7; temperature 30 °C and inoculum dosage 0.06 g L⁻¹) with the least half-life of 1.17 days and degradation constant of 0.588 per day. Lindane degradation was tested with various kinetic models and results revealed that the reaction could be described best by first-order and pseudo first-order models. In addition, involvement of the enzymes viz. dechlorinase, dehalogenase, dichlorohydroquinone reductive dechlorinase, lignin peroxidase and manganese peroxidase was noted during lindane degradation. Addition of H2O2 in the mineral medium showed 32 % enhancement of lindane degradation within 3 days. Based on the metabolites identified by GC-MS and FTIR analysis, sequential process of lindane degradation by Candida VITJzN04 was proposed. To the best of our knowledge, this is the first report of isolation and characterization of lindane-degrading Candida sp. and elucidation of enzyme systems during the degradation process.

A soluble diacylglycerol acyltransferase is involved in triacylglycerol biosynthesis in the oleaginous yeast Rhodotorula glutinis.

PubMed

Rani, Sapa Hima; Saha, Saikat; Rajasekharan, Ram

2013-01-01

The biosynthesis of triacylglycerol (TAG) occurs in the microsomal membranes of eukaryotes. Here, we report the identification and functional characterization of diacylglycerol acyltransferase (DGAT), a member of the 10 S cytosolic TAG biosynthetic complex (TBC) in Rhodotorula glutinis. Both a full-length and an N-terminally truncated cDNA clone of a single gene were isolated from R. glutinis. The DGAT activity of the protein encoded by RgDGAT was confirmed in vivo by the heterologous expression of cDNA in a Saccharomyces cerevisiae quadruple mutant (H1246) that is defective in TAG synthesis. RgDGAT overexpression in yeast was found to be capable of acylating diacylglycerol (DAG) in an acyl-CoA-dependent manner. Quadruple mutant yeast cells exhibit growth defects in the presence of oleic acid, but wild-type yeast cells do not. In an in vivo fatty acid supplementation experiment, RgDGAT expression rescued quadruple mutant growth in an oleate-containing medium. We describe a soluble acyl-CoA-dependent DAG acyltransferase from R. glutinis that belongs to the DGAT3 class of enzymes. The study highlights the importance of an alternative TAG biosynthetic pathway in oleaginous yeasts.

Classification of yeast cells from image features to evaluate pathogen conditions

NASA Astrophysics Data System (ADS)

van der Putten, Peter; Bertens, Laura; Liu, Jinshuo; Hagen, Ferry; Boekhout, Teun; Verbeek, Fons J.

2007-01-01

Morphometrics from images, image analysis, may reveal differences between classes of objects present in the images. We have performed an image-features-based classification for the pathogenic yeast Cryptococcus neoformans. Building and analyzing image collections from the yeast under different environmental or genetic conditions may help to diagnose a new "unseen" situation. Diagnosis here means that retrieval of the relevant information from the image collection is at hand each time a new "sample" is presented. The basidiomycetous yeast Cryptococcus neoformans can cause infections such as meningitis or pneumonia. The presence of an extra-cellular capsule is known to be related to virulence. This paper reports on the approach towards developing classifiers for detecting potentially more or less virulent cells in a sample, i.e. an image, by using a range of features derived from the shape or density distribution. The classifier can henceforth be used for automating screening and annotating existing image collections. In addition we will present our methods for creating samples, collecting images, image preprocessing, identifying "yeast cells" and creating feature extraction from the images. We compare various expertise based and fully automated methods of feature selection and benchmark a range of classification algorithms and illustrate successful application to this particular domain.

sup 31 P NMR measurements of the ADP concentration in yeast cells genetically modified to express creatine kinase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brindle, K.; Braddock, P.; Fulton, S.

1990-04-03

Rabbit muscle creatine kinase has been introduced into the yeast Saccharomyces cerevisiae by transforming cells with a multicopy plasmid containing the coding sequence for the enzyme under the control of the yeast phosphoglycerate kinase promoter. The transformed cells showed creating kinase activities similar to those found in mammalian heart muscle. {sup 31}P NMR measurements of the near-equilibrium concentrations of phosphocreatine and cellular pH together with measurements of the total extractable concentrations of phosphocreatine and creatine allowed calculation of the free ADP/ATP ratio in the cell. The calculated ratio of approximately 2 was considerably higher than the ratio of between 0.06more » and 0.1 measured directly in cell extracts.« less

New yeasts-new brews: modern approaches to brewing yeast design and development.

PubMed

Gibson, B; Geertman, J-M A; Hittinger, C T; Krogerus, K; Libkind, D; Louis, E J; Magalhães, F; Sampaio, J P

2017-06-01

The brewing industry is experiencing a period of change and experimentation largely driven by customer demand for product diversity. This has coincided with a greater appreciation of the role of yeast in determining the character of beer and the widespread availability of powerful tools for yeast research. Genome analysis in particular has helped clarify the processes leading to domestication of brewing yeast and has identified domestication signatures that may be exploited for further yeast development. The functional properties of non-conventional yeast (both Saccharomyces and non-Saccharomyces) are being assessed with a view to creating beers with new flavours as well as producing flavoursome non-alcoholic beers. The discovery of the psychrotolerant S. eubayanus has stimulated research on de novo S. cerevisiae × S. eubayanus hybrids for low-temperature lager brewing and has led to renewed interest in the functional importance of hybrid organisms and the mechanisms that determine hybrid genome function and stability. The greater diversity of yeast that can be applied in brewing, along with an improved understanding of yeasts' evolutionary history and biology, is expected to have a significant and direct impact on the brewing industry, with potential for improved brewing efficiency, product diversity and, above all, customer satisfaction. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.