Search results for "YEAST"

Comparison of Components Released by Fermented or Active Dried Yeasts after Aging on Lees in a Model Wine

2003

Comparison of different components released during autolysis with fermented or active dried yeast, which has never been reported previously, is related in this paper. Three autolysates were elaborated with Saccharomyces cerevisiae in a model wine (pH 3.5) at 30 or 18 degrees C. Composition of the autolysate appears to depend on both the growth medium and the physiological state of the yeast. The autolysate obtained from active dried yeast presents a higher total nitrogen concentration (a factor of 1.5-1.9 for the fermented yeast autolysate), a greater proportion of free amino acids (42 vs 16-25%), the lowest proportion of oligopeptides (25 vs 31-37%) and polypeptides (27 vs 45-34%), and an …

Protease A activity and nitrogen fractions released during alcoholic fermentation and autolysis in enological conditions

2000

Determination of protease A activity during alcoholic fermentation of a synthetic must (pH 3.5 at 25 degrees C) and during autolysis showed that a sixfold induction of protease A activity occurred after sugar exhaustion, well before 100% cell death occurred. A decrease in protease A activity was observed when yeast cell autolysis started. Extracellular protease A activity was detected late in the autolysis process, which suggests that protease A is not easily released. Evolution of amino acids and peptides was determined during alcoholic fermentation and during autolysis. Amino acids were released in early stationary phase. These amino acids were subsequently assimilated during the fermenta…

Evaluation of yeasts from Ecuadorian chicha by their performance as starters for alcoholic fermentations in the food industry

2020

Yeasts involved in the spontaneous fermentation of traditional beverages like chicha (indigenous Andean beer) may have the potential to be used as starter cultures to improve the quality and microbiological safety of these products, but also as non-conventional alternatives to other food alcoholic fermentations. In this research, we isolated, identified and characterised yeast strains from four Ecuadorian chichas made by using four different raw materials: rice (RC), oat (OC), grape (GC) and a mixture of seven corn varieties (yamor, YC). Finally, 254 yeast isolates were obtained and identified by molecular methods. Eleven yeast genera and 16 yeast species were identified with relatively few…

Bioencapsulation of living bacteria (Escherichia coli) with poly(silicate) after transformation with silicatein-α gene

2007

Bioencapsulation is an intriguing way to immobilize biological materials, including cells, in silica, metal-oxides or hybrid sol-gel polymers. Until now only the sol-gel precursor technology was utilized to immobilize bacteria or yeast cells in silica. With the discovery of silicatein, an enzyme from demosponges that catalyzes the formation of poly(silicate), it became possible to synthesize poly(silicate) under physiological (ambient) conditions. Here we show that Escherichia coli can be transformed with the silicatein gene, its expression level in the presence of isopropyl beta-D-thiogalactopyranoside (IPTG) can be efficiently intensified by co-incubation with silicic acid. This effect co…

Putting molecules in their place.

2014

Each class of microscope is limited to imaging specific aspects of cell structure and/or molecular organization. However, imaging the specimen by complementary microscopes and correlating the data can overcome this limitation. Whilst not a new approach, the field of correlative imaging is currently benefitting from the emergence of new microscope techniques. Here we describe the correlation of cryogenic fluorescence tomography (CFT) with soft X‐ray tomography (SXT). This amalgamation of techniques integrates 3D molecular localization data (CFT) with a high‐resolution, 3D cell reconstruction of the cell (SXT). Cells are imaged in both modalities in a near‐native, cryopreserved state. Here we…

Beta-galactosidase activity assay for yeast

2019

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…

Corrigendum to “External conditions inversely change the RNA polymerase II elongation rate and density in yeast” [Biochim. Biophys. Acta 1829/11 (201…

2017

Tributyltin affects phagocytic activity of Ciona intestinalis hemocytes

1995

Organotin compounds have been used in marine anti-fouling paints as biocides. Because tunicates are vulnerable to these compounds in their natural habitats, we used Ciona intestinalis to establish an assay for phagocytosis in vitro of yeast by hemocytes after exposure to different concentrations (0.0015, 0.015, 0.15 and 1.5 microM) of four organotin compounds: tributyltin (TBT), triphenyltin (TPT), dibutyltin (DBT) and diphenyltin (DPT). To evaluate the phagocytic activity, we used a method based on fluorescence excitation of yeast pre-treated with eosin-Y. The percentage of phagocytosis decreased from 45.1 +/- 3.49 to 22.4 +/- 5.14 at 1.5 microM of TBT (P0.001); it was significantly reduce…

Exponential growth phase cells of the osmotolerant yeast Debaryomyces hansenii are extremely resistant to dehydration stress

2001

Abstract The osmotolerant yeast Debaryomyces hansenii is highly resistant to dehydration stress and this tolerance was more pronounced for cells taken from the exponential growth phase than from the stationary phase. Growth of D. hansenii in medium containing 10% (w v −1 ) NaCl, resulted in an additional increase in cellular resistance to dehydration, which was most marked for stationary phase cells. It is expected that further investigations of the mechanisms behind this exceptional dehydrational tolerance will reveal new approaches for improvement of the quality of dry yeast.