Search results for "Pichia"

Influence of freezing temperatures prior to freeze-drying on viability of yeasts and lactic acid bacteria isolated from wine

2017

Aims To determine the effect of three different freezing temperatures on post-freeze-drying survival rates of wine yeasts and lactic acid bacteria (LAB). To know if a similar freeze-drying protocol can be used for both micro-organisms. Methods and Results Cells from liquid culture media were recovered and concentrated in appropriate lyoprotectants. Aliquots of each strain were frozen at −20, −80 and −196°C before vacuum drying. Viable cell counts were done before freezing and after freeze-drying. Survival rates were calculated. Freezing temperatures differently affected yeast and bacteria survival. The highest survival rates were obtained at −20 and −80°C for yeasts, but at −196°C for LAB. …

2017

Nitrogen sources in the must are important for yeast metabolism, growth, and performance, and wine volatile compounds profile. Yeast assimilable nitrogen (YAN) deficiencies in grape must are one of the main causes of stuck and sluggish fermentation. The nitrogen requirement of Saccharomyces cerevisiae metabolism has been described in detail. However, the YAN preferences of non-Saccharomyces yeasts remain unknown despite their increasingly widespread use in winemaking. Furthermore, the impact of nitrogen consumption by non-Saccharomyces yeasts on YAN availability, alcoholic performance and volatile compounds production by S. cerevisiae in sequential fermentation has been little studied. With…

Purification and characterization of recombinant brazzein secreted by the yeast Pichia pastoris

2008

Meeting Abstract; International audience

Glucose and Ethanol Tolerant Enzymes Produced by Pichia (Wickerhamomyces) Isolates from Enological Ecosystems

2012

A total of 17 Pichia ( Wickerhamomyces ) isolates obtained from enological ecosystems in the Utiel-Requena Spanish region were characterized by physiological (using API 20C AUX strips and ID Yeast Plus System miniaturized identification systems) and molecular (PCR-RFLP and sequencing) techniques as belonging to the species P. fermentans, P. membranifaciens , and W. anomalus . Data support the reclassification of P. anomala as Wickerhamomyces anomalus . In order to characterize their enzymatic abilities, xylanase, β-glucosidase, lipase, esterase, protease, and pectinase qualitative and quantitative assays were made. Wickerhamomyces anomalus and P. membranifaciens were the most interesting sp…

Characterization of an ethanol-tolerant 1,4-β-xylosidase produced byPichia membranifaciens

2012

Aims:  The purification and biochemical properties of the 1,4-β-xylosidase of an oenological yeast were investigated. Methods and Results:  An ethanol-tolerant 1,4-β-xylosidase was purified from cultures of a strain of Pichia membranifaciens grown on xylan at 28°C. The enzyme was purified by sequential chromatography on DEAE cellulose and Sephadex G-100. The relative molecular mass of the enzyme was determined to be 50 kDa by SDS-PAGE. The activity of 1,4-β-xylosidase was optimum at pH 6·0 and at 35°C. The activity had a Km of 0·48 ± 0·06 mmol l−1 and a Vmax of 7·4 ± 0·1 μmol min−1 mg−1 protein for p-nitrophenyl-β-d-xylopyranoside. Conclusions:  The enzyme characteristics (pH and thermal st…

Estimation of recombinant protein production in Pichia pastoris base don a constraint-based model

2012

[EN] A previously validated constraint based model and possibilistic MFA have been used to design a simple estimator of protein production rate in Pichia pastoris cultures. A structured model of the yeast P. pastoris metabolism is used to predict the balance of key energetic equivalents such as ATP from available measurements, mainly substrate consumption, gases exchange rates and biomass specific growth. It has been shown that ATP flux can be related to biomass growth and protein productivity specific rates by linear regression. Cross-validation has been applied for robust parameter fitting on the basis of chemostat, steady-state experimental conditions. In this way, protein estimation can…

Lipolytic activity of the yeast species associated with the fermentation/storage phase of ripe olive processing.

2010

9 páginas, 4 figuras, 5 tablas.-- El Pdf del artículo es la copia de autor.

Occurrence of Fusarium mycotoxins in Italian cereal and cereal products from organic farming.

2013

In the present study, the occurrence of eighteen mycotoxins, nine trichothecenes (deoxynivalenol, 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, nivalenol, neosolaniol, diacetoxyscirpenol, fusarenon-X, T-2 toxin and HT-2 toxin), three zearalenones (zearalenone, α-zearalenol and β-zearalenol), and six emergent mycotoxins, beauvericin and five enniatins (A, A1, B, B1 and B4), was monitored in different Italian organic cereals and cereal products by using a liquid chromatography coupled to triple quadrupole mass spectrometry method. A total of 93 organic cereal samples (wheat, barley, rye and oat) were collected from Italy. Limits of quantification ranged from 5 to 15 μg/kg. 80% of analyze…

Efficient Expression and Crystallization System of Cancer-Associated Carbonic Anhydrase Isoform IX.

2015

Human carbonic anhydrase IX (CA IX) is overexpressed in a number of solid tumors and is considered to be a marker for cellular hypoxia that it is not produced in most normal tissues. CA IX contributes to the acidification of the extracellular matrix, which, in turn, favors tumor growth and metastasis. Therefore, CA IX is considered to be a promising anti-cancer drug target. However, the ability to specifically target CA IX is challenging due to the fact that the human genome encodes 15 different carbonic anhydrase isoforms that have a high degree of homology. Furthermore, structure-based drug design of CA IX inhibitors so far has been largely unsuccessful due to technical difficulties regar…

PARTIAL SEQUENCING OF THE BETA-GLUCOSIDASE-ENCODING GENE FROM YEAST STRAINS ISOLATED FROM MUSTS AND WINES

2008

The aim of the present work was the identification of the gene encoding for β-glucosidase and its partial sequencing in the strainsPichia anomala AL112,Hanseniaspora uvarum Y8 andSaccharomyces cerevisiae AL41. To this aim degenerated primers, designed on the basis of aminoacid similarities of four known yeast β-glucosidases, have been used in PCR amplifications. An expected fragment of about 200 bp was amplified from all the DNAs, cloned and sequenced. Sequence homology demonstrated for the first time the presence of a β-glucosidase encoding gene inHanseniaspora uvarum andSaccharomyces cerevisiae.