The aim of the present work was to study the incorporation of some microelements in the yeast Saccharomyces cerevisiae and its impact on the physiological state of the yeast cells during the ...alcoholic fermentation. The cultivations were performed on molasses medium in anaerobic (thermostat) and semiaerobic (shaker) conditions, with and without the addition of zinc, copper and manganese sulphate (0.1 g/L of each) at 30 degree C and different pH values of the medium (3.5-6.0) for 8 h. The addition of the mentioned salts in molasses medium enhanced the yield of the yeast biomass up to 30% in semiaerobic conditions, but the ethanol yield was changed very little. On the other hand, in anaerobic conditions the yields of the yeast biomass were increased up to 10% and alcohol yield up to 20%. After the fermentations were performed, the concentration of metal ions in yeast cells was determined. Different values were achieved depending on the used growth conditions. The highest amount of Zn ions in dry matter (700 microg/g) was incorporated in the yeast biomass under anaerobic conditions. In contrast, the incorporation of Cu and Mn was preferred in semiaerobic conditions and the highest value of Cu super(2+) ions in dry matter (1100 microg/g) and Mn super(2+) in dry matter (300 microg/g) in yeast biomass were obtained. Optimal pH for all ion incorporations was between 4 and 5.
The production of
Saccharomyces cerevisiae cells enriched with copper and the effects of adding copper ions to different media on yeast cell growth and ethanol production were studied. In the media ...Cu
2+ concentrations of up to 0.094 mM had no effect on alcoholic fermentation, whereas higher Cu
2+ concentrations markedly decreased yeast cell growth rate and ethanol production. Under static conditions, the maximum amounts of copper uptake (
i.e., 1.16 mg/g, 1.2 mg/g and 0.81 mg/g dry matter yeast biomass for glucose, sucrose and molasses media, respectively) were obtained after 8 h of fermentation, whereas under dynamic conditions smaller amounts of copper uptake (
i.e., 0.98 mg/g, 1.02 mg/g and 0.7 mg/g dry matter yeast biomass for glucose, sucrose and molasses media, respectively) were obtained after 6 h of fermentation.
β-Glucans are glucose polymers that naturally occur in yeasts, molds, algae, mushrooms, bacteria, oats and barley. Immunostimulation is one of the most important properties of β-glucans. They are ...classified as biological response modifiers and because of their biological activities they can be used in human and veterinary medicine and pharmacy. Additionally, β-glucans show interesting physicochemical properties and therefore could be applied in food and feed production as well as in cosmetic and chemical industries. Immunomodulation by β-glucan, both in vitro and in vivo, inhibits cancer cell growth and metastasis and prevents or reduces bacterial infection. In humans, dietary β-glucan lowers blood cholesterol, improves glucose utilization by body cells and also helps wound healing. β-Glucans work, in part, by stimulating the innate immune mechanism to fight a range of foreign challenges and could be used as an adjuvant, in combination with anti infective or antineoplastic agents, radiotherapy, and a range of topical agents and nutrients. The structure of β-glucans depends on the source they are isolated from. Native β-glucan molecules can be linked and branched in several ways. Biological properties of different β-glucan molecules are dependent on their molecular structure. Some authors claim that the β-(1→3), (1→6)-glucan derived from yeast Saccharomyces cerevisiae produce the highest biological effects. Thus, in this review the β-glucans and their metabolic activity are discussed, with the special accent on those isolated from yeast. Other possible β-glucan applications, directed to cosmetic production, non-medical application in pharmaceutical and chemical industry, are also discussed.
Fermentations with yeastSaccharomyces cerevisiae in semiaerobic and in static conditions with the addition of chromic chloride into the used molasses medium were analysed. It was proved that the ...addition of optimal amounts of CrCl^sub 3^ into the basal medium enhanced the kinetics of alcohol fermentations. The addition of 200 mg/l CrCl^sub 3^ into the medium stimulated both the yeast growth and the ethanol production in all experimental conditions. On the other hand, the results showed that Cr^sup 3+^ ions were incorporated into yeast cells during fermentation. Under these conditions the accumulation of Cr^sup 3+^ ions was performed by yeast cells during the exponential growth phase, and with enriched amounts of 30-45 (μg/g^sub d.m.^ of cells. Yeast biomass enriched with chromium ions was extracted with 01 mol/l NH^sub 4^OH assuming that the extracts had the glucose tolerance factor (GTF). Then the extracts were passed through a gel-filtration column in order to isolate and purify the GTF. The presence of GTF in the purified fractions was determined by measuring the absorbance at 260 nm. It is evident from the obtained results that the added purified fractions enhanced the rates of CO^sub 2^ production as well as the glucose utilization during alcoholic fermentation. As expected, the enhancement of both rates depended on the amounts of extracts added to the fermentation substrate. Thus, it is evident that purified extracts contained the GTF compound, and that Cr^sup 3+^ ions were bonded to the protein molecule.PUBLICATION ABSTRACT
Different β-glucans are found in a variety of natural sources such as bacteria, yeast, algae, mushrooms, barley and oat. They have potential use in medicine and pharmacy, food, cosmetic and chemical ...industries, in veterinary medicine and feed production. The use of different β-glucans in food industry and their main characteristics important for food production are described in this paper.
This review focuses on beneficial properties and application of β-glucans isolated from different yeasts, especially those that are considered as waste from brewing industry. Spent brewer’s yeast, a by-product of beer production, could be used as a raw-material for isolation of β-glucan. In spite of the fact that large quantities of brewer’s yeast are used as a feedstuff , certain quantities are still treated as a liquid waste. β-Glucan is one of the compounds that can achieve a greater commercial value than the brewer’s yeast itself and maximize the total profitability of the brewing process. β-Glucan isolated from spent brewer’s yeast possesses properties that are benefi cial for food production. Therefore, the use of spent brewer’s yeast for isolation of β-glucan intended for food industry would represent a payable technological and economical choice for breweries.
Fermentations with yeast Saccharomyces cerevisiae in semiaerobic and in static conditions with the addition of chromic chloride into the used molasses medium were analysed. It was proved that the ...addition of optimal amounts of CrCl3 into the basal medium enhanced the kinetics of alcohol fermentations. The addition of 200 mg/l CrCl3 into the medium stimulated both the yeast growth and the ethanol production in all experimental conditions. On the other hand, the results showed that Cr3+ ions were incorporated into yeast cells during fermentation. Under these conditions the accumulation of Cr3+ ions was performed by yeast cells during the exponential growth phase, and with enriched amounts of 30-45 microg/g(d.m) of cells. Yeast biomass enriched with chromium ions was extracted with 0.1 mol/l NH4OH assuming that the extracts had the glucose tolerance factor (GTF). Then the extracts were passed through a gel-filtration column in order to isolate and purify the GTF. The presence of GTF in the purified fractions was determined by measuring the absorbance at 260 nm. It is evident from the obtained results that the added purified fractions enhanced the rates of CO2 production as well as the glucose utilization during alcoholic fermentation. As expected, the enhancement of both rates depended on the amounts of extracts added to the fermentation substrate. Thus, it is evident that purified extracts contained the GTF compound, and that Cr3+ ions were bonded to the protein molecule.
Kinetics of alcoholic fermentation by yeast Kluyveromyces marxianusZIM 75 in various media based on whey and molasses were monitored. The fermentations were performed under static and semiaerobic ...conditions at 34°C. Deproteinized whey and molasses were mixed in various proportions to give final sugar mass concentrations of 5%, 10% and 15% in medium. The experiments conducted showed that medium with 10 % of sugar (sucrose:lactose=1:1) is optimal for alcoholic fermentations in static and semiaerobic conditions. The best ethanol yield after 24 hours of fermentation was 4.05 % (V/V) in static conditions and 4.9 % (V/V) in semiaerobic conditions. The biomass yield was 7.78 g d.m./L in semiaerobic conditions and 3.19 g d.m./L in static conditions.
The conditions of lactose hydrolysis with enzyme preparation of D-galactosidase were investigated. The aim of this work was to considered the use of whey in fermentative processes with yeast ...Saccharomyces cerevisiae. Enzymatic hydrolysis was conducted at different temperatures, with different lactose concentrations in medium and different concentrations of added enzyme. The results show that optimal temperature for hydrolysis was 40°C. The optimal amount of enzyme preparation was 2 gL-1 in lactose medium with 5-10 % lactose.
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