Brewer's Yeast Research Articles

Induced gene expression in industrial Saccharomyces pastorianus var. carlsbergensis TUM 34/70: evaluation of temperature and ethanol inducible native promoters.

Induced gene expression is an important trait in yeast metabolic engineering, but current regulations prevent the use of conventional expression systems, such as galactose and copper, in food and beverage fermentations. This article examines the suitability of temperature-inducible native promoters for use in the industrial yeast strain Saccharomyces pastorianus var. carlsbergensis TUM 34/70 under brewing conditions. Ten different promoters were cloned and characterized under varying temperature shifts and ethanol concentrations using a green fluorescent protein reporter. The activities of these promoters varied depending upon the stress conditions applied. A temperature shift to 4°C led to the highest fold changes of PSSA3, PUBI4 and PHSP104 by 5.4, 4.5 and 5.0, respectively. Ethanol shock at 24°C showed marked, concentration-dependent induction of the promoters. Here, PHSP104 showed its highest induction at ethanol concentrations between 4% (v/v) and 6% (v/v). The highest fold changes of PSSA3 and PUBI4 were found at 10% (v/v) ethanol. In comparison, the ethanol shock at a typical fermentation temperature (12°C) leads to lower induction patterns of these promoters. Taken together, the data show that three promoters (PHSP104, PUBI4 and PSSA3) have high potential for targeted gene expression in self-cloning brewing yeast using temperature shifts.

Screening for new brewing yeasts in the non-Saccharomyces sector with Torulaspora delbrueckii as model.

This study describes a screening system for future brewing yeasts focusing on non-Saccharomyces yeasts. The aim was to find new yeast strains that can ferment beer wort into a respectable beer. Ten Torulaspora delbrueckii strains were put through the screening system, which included sugar utilization tests, hop resistance tests, ethanol resistance tests, polymerase chain reaction fingerprinting, propagation tests, amino acid catabolism and anabolism, phenolic off-flavour tests and trial fermentations. Trial fermentations were analysed for extract reduction, pH drop, yeast concentration in bulk fluid and fermentation by-products. All investigated strains were able to partly ferment wort sugars and showed high tolerance to hop compounds and ethanol. One of the investigated yeast strains fermented all the wort sugars and produced a respectable fruity flavour and a beer of average ethanol content with a high volatile flavour compound concentration. Two other strains could possibly be used for pre-fermentation as a bio-flavouring agent for beers that have been post-fermented by Saccharomyces strains as a consequence of their low sugar utilization but good flavour-forming properties.

How do yeast cells become tolerant to high ethanol concentrations?

The brewer's yeast Saccharomyces cerevisiae displays a much higher ethanol tolerance compared to most other organisms, and it is therefore commonly used for the industrial production of bioethanol and alcoholic beverages. However, the genetic determinants underlying this yeast's exceptional ethanol tolerance have proven difficult to elucidate. In this perspective, we discuss how different types of experiments have contributed to our understanding of the toxic effects of ethanol and the mechanisms and complex genetics underlying ethanol tolerance. In a second part, we summarize the different routes and challenges involved in obtaining superior industrial yeasts with improved ethanol tolerance.

Antiulcer and antiproliferative properties of spent brewer's yeast peptide extracts for incorporation into foods.

The main objective was to study the antiulcer and antiproliferative potential of yeast peptide extract for further incorporation into functional foods. Peptide concentrates were obtained by hydrolysis of spent brewer's yeast proteins followed by a filtration process. In order to prove the possible protection of gastric mucosa, an animal model with ulcerative lesions caused by oral administration of absolute ethanol was used. The peptide fraction <3 kDa was able to reduce gastric injuries to significant levels (p < 0.001) and the effective dose (DE50) was 816 mg per kg bw. The cytoprotective effect appears to depend on a prostaglandin-mediated mechanism and also on a nonspecific mechanism. The antiproliferative activity of the extract in nine different human tumoral cell lines was tested. The results exhibited a promising antiproliferative activity against the cell line K-562 (leukemia). The results suggest that a new peptide extract can be used to develop new value-added functional food products, although further studies are required.

Chromium supplementation in patients with type 2 diabetes and high risk of type 2 diabetes: a meta-analysis of randomized controlled trials

Chromium is an essential trace mineral for carbohydrate and lipid metabolism, which is currently prescribed to control diabetesmellitus. Results of previous systematic reviews and meta-analyses of chromium supplementation and metabolic profiles in diabetes have beeninconsistent. The objective of this meta-analysis was to assess the effects on metabolic profiles and safety of chromium supplementation in type 2diabetes mellitus and cholesterol. Literature searches in PubMed, Scopus and Web of Science were made by use of related terms-keywords and randomized clinicaltrials during the period of 2000-2014. Thirteen trials fulfilled the inclusion criteria and were included in this systematic review. Total doses of Cr supplementation and brewer'syeast ranged from 42 to 1,000 μg/day, and duration of supplementation ranged from 30 to 120 days. The analysis indicated that there was a significanteffect of chromium supplementation in diabetics on fasting plasma glucose with a weighted average effect size of -29.26 mg/dL, p = 0.01,CI 95% = -52.4 to -6.09; and on total cholesterol with a weighted average effect size of -6.7 mg/dL, p = 0.01, CI 95% = -11.88 to -1.53. The available evidence suggests favourable effects of chromium supplementation on glycaemic control in patients with diabetes.

Isolation and Characterization of a Variant Manganese Resistant Strain of Saccharomyces cerevisiae.

Manganese contamination in water is one of the most serious problems in Southeast Asian countries, including Vietnam. Bioremediation using microorganisms, especially from the brewing yeast Saccharomyces cerevisiae, is expected to be a useful technique to remove manganese from contaminated water. Yeast strain S. cerevisiae BY4741 as the wild-type strain and some manganese-accumulating mutants bred from BY4741 were examined for cell growth and manganese accumulation in YPD liquid medium containing various concentrations of Mn2+. Variants accumulating larger concentrations of manganese were isolated by the repeated screening of survivors in YPD media containing10mM Mn2+. Manganese was accumulated by the yeast cells during growth, but the growth of BY4741 was retarded with increasing Mn2+ concentrations and almost inhibited at 15mM Mn2+. One variant isolate, named IM3, showed no retardation of growth up to 15 mM Mn2+ and could absorb over 4-fold more manganese than the BY4741 strain. Effects of culture temperature and pH on the growth and manganese accumulation were analyzed for IM3. Maximum accumulation was shown at 30℃, pH 6.0 while the optimal growth was shown at 37℃, pH 5.0 - 7.0. Interestingly, IM3 could grow a little at pH 9.0 when manganese was added to the culture media, while it could not grow without the addition of manganese.

Effects of food availability on growth and reproduction of the deep-sea pedunculate barnacle Heteralepas canci

Sessile animals living on continental shelves or slopes may adjust their growth and reproduction according to temporally and spatially variable food availability, but little information is available on these animals to date. We collected the pedunculate barnacle Heteralepas canci on a continental slope at a depth of 229m off Cape Nomamisaki in southern Japan. We developed a rearing method for the barnacles and studied their growth and reproduction at different food levels in the laboratory. A total of 136 individual H. canci were fed with Artemia salina larvae and brewer's yeast at three different food levels for 100 days. Both the growth and the ovary development were delayed when food availability was low, whereas the survival rate was lower at the high food level. In addition, an individual survived under complete starvation for 167 days. We concluded that H. canci has plastic life history traits that are adaptive for variable food availability.

The use of chitooligosaccharide in beer brewing for protection against beer-spoilage bacteria and its influence on beer performance.

To identify a biological preservative that can protect beer from microbial contamination, which often results in the production of turbidity and off-flavor. The antimicrobial activity of a chitooligosaccharide against beer-spoilage bacteria and its effect on the fermentation performance of brewer's yeast was studied. Chitooligosaccharide with an average 2 kDa molecular weight was the best at inhibiting all tested beer-spoilage bacteria. The application of chitooligosaccharide in the brewing process did not influence the fermentation of brewer's yeast. The change in beer performance induced by the contamination of Lactobacillus brevis could be effectively controlled by application of chitooligosaccharide in the beer brewing process. The experimental data suggested that chitooligosaccharide should be an excellent preservative to inhibit beer-spoilage bacteria in the brewing process and in the end product.

Yeast-Breeding Efforts Augur a Fresh, Flavored Diversity for Lagers

By creating new genetic crosses among relevant brewing yeasts, lager beers can be made more variable in flavor—letting them compete more favorably perhaps with ales, long-known for their broader taste variability, according to Kevin Verstrepen and Stijn Mertens of the University of Leuven, Belgium, and their collaborators. Details appeared 25 September in Applied and Environmental Microbiology (doi:10.1128/AEM.02464–15/).

Impact of brewer's yeast extract and levamisole in diets with vegetable oils on the growth, chemical composition, and immunological and biochemical blood parameters of pikeperch (Sander lucioperca)

Impact of brewer's yeast extract and levamisole in diets with vegetable oils on the growth, chemical composition, and immunological and biochemical blood parameters of pikeperch (Sander lucioperca)

Pharmacological effects of ethanol extract of Egyptian Artemisia herba-alba in rats and mice

ObjectiveTo investigate some pharmacological effects including gastroprotective, anti-inflammatory, analgesic, antipyretic and in vitro antioxidant effects of Artemisia herba-alba extract in different experimental models. MethodsInflammation was induced in rat paw by subcutaneous injection of 1% (v/v) carrageenan solution. Writhes was induced in mice by intraperitoneal injection of 0.6% (v/v) acetic acid solution. Pyrexia was induced using Brewer's yeast suspension. Gastric lesion was induced in rats by oral administration of 99% ethanol. The anti-inflammatory, analgesic, antipyretic and gastroprotective activities of Artemisia herba-alba extract were investigated respectively. In vitro antioxidant effect was investigated using DPPH free radical. ResultsThe plant extract showed anti-inflammatory effect in carrageenan-induced paw edema in rats, analgesic effect against acetic acid-induced writhing, and antipyretic activity in Brewer's yeast model of pyrexia. Besides, it was shown to be a gastroprotective agent against ethanol-induced gastric ulcers. The plant also exhibited a free radical scavenging potential in an in vitro antioxidant study using DPPH. ConclusionsThe results validate the use of the investigated plant in traditional medicine for different ailments.

Ochratoxin A in brewer's yeast used as food supplement.

Brewer's yeasts are rich in vitamins of the B-group and contain other nutritive factors; therefore, they are recommended as valuable food supplements for people with special dietary requirements like pregnant women, children, and adolescents, or for people with high physical activity. Additionally, certain strains of brewer's yeast are known to be capable of adsorbing xenobiotics such as mycotoxins. Because of that, these yeasts are regarded as having positive effects in food, beverage, and feed technology. Their potential to bind mycotoxins such as ochratoxin A (OTA), however, can subsequently lead to a contamination of such brewer's yeasts used as food supplements. In the present study, we analyzed 46 samples of brewer's yeasts for the occurrence of OTA by HPLC with fluorescence detector (HPLC-FLD) and for confirmatory measurements by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Nearly 90% of the samples were contaminated with OTA, the levels ranging from the limit of detection (LOD, 0.01 μg/kg) to 4.2 μg/kg. The mean and median levels of contamination were 0.49 and 0.27 μg/kg, respectively. Based on these results, the additional weekly OTA exposure by regularly consuming such supplements was assessed. Depending on different subpopulations (adults, children) and levels of contamination used for calculation, the additional OTA intake via brewer's yeast products ranged from 9.3% (mean case) to 114% (worst case) of the published mean weekly OTA intake in Germany (adults 279.3 ng, children 195.3 ng). At present, maximum levels for OTA in nutritional supplements like brewer's yeast do not exist. Based on our results, however, it is recommended that producers of these dietary supplements should include mycotoxin analyses in ongoing and future self-monitoring programs and in product quality checks.

Physicochemical characterization of sahti, an ‘ancient’ beer style indigenous to Finland

Sahti, a strong, unhopped farmhouse beer flavoured with juniper, is still actively brewed in rural areas in Finland. Presented here is the first comprehensive analysis of the physical and chemical properties of this unique beer style. Twelve sahti samples from the southwest of Finland were analysed and, while properties varied, the beers generally had high levels of alcohol (mean = 7.9% ABV) and high residual extract (mean = 9.5°P). Foam stability was negligible, as is typical for the style, and glycerol concentrations at 3.1 – 4.7 g L−1 were higher than in reference beers (commercial lager, wheat beer and porter). These features may be attributed to the very high gravity conditions employed in brewing sahti beers. Bitterness levels were relatively low (3–13 IBU) owing to the absence or moderate use of hops. All samples contained detectable levels of the clove-like compound 4-vinylguaiacol owing to the use of baker's rather than brewer's yeast for brewing. Concentrations of higher alcohols and esters were high, with many individual aroma compounds being above the normal flavour thresholds. Results have highlighted the uniqueness of this style of beer in comparison to commercially available beers and have contributed to our understanding of the reasons for the particular sensorial properties of this traditional beer style. Copyright © 2015 The Institute of Brewing & Distilling

Genome-wide array-CGH analysis reveals YRF1 gene copy number variation that modulates genetic stability in distillery yeasts.

Industrial yeasts, economically important microorganisms, are widely used in diverse biotechnological processes including brewing, winemaking and distilling. In contrast to a well-established genome of brewer's and wine yeast strains, the comprehensive evaluation of genomic features of distillery strains is lacking. In the present study, twenty two distillery yeast strains were subjected to electrophoretic karyotyping and array-based comparative genomic hybridization (array-CGH). The strains analyzed were assigned to the Saccharomyces sensu stricto complex and grouped into four species categories: S. bayanus, S. paradoxus, S. cerevisiae and S. kudriavzevii. The genomic diversity was mainly revealed within subtelomeric regions and the losses and/or gains of fragments of chromosomes I, III, VI and IX were the most frequently observed. Statistically significant differences in the gene copy number were documented in six functional gene categories: 1) telomere maintenance via recombination, DNA helicase activity or DNA binding, 2) maltose metabolism process, glucose transmembrane transporter activity; 3) asparagine catabolism, cellular response to nitrogen starvation, localized in cell wall-bounded periplasmic space, 4) siderophore transport, 5) response to copper ion, cadmium ion binding and 6) L-iditol 2- dehydrogenase activity. The losses of YRF1 genes (Y' element ATP-dependent helicase) were accompanied by decreased level of Y' sequences and an increase in DNA double and single strand breaks, and oxidative DNA damage in the S. paradoxus group compared to the S. bayanus group. We postulate that naturally occurring diversity in the YRF1 gene copy number may promote genetic stability in the S. bayanus group of distillery yeast strains.

A codon model of nucleotide substitution with selection on synonymous codon usage.

The quality of phylogenetic inference made from protein-coding genes depends, in part, on the realism with which the codon substitution process is modeled. Here we propose a new mechanistic model that combines the standard M0 substitution model of Yang (1997) with a simplified model from Gilchrist (2007) that includes selection on synonymous substitutions as a function of codon-specific nonsense error rates. We tested the newly proposed model by applying it to 104 protein-coding genes in brewer's yeast, and compared the fit of the new model to the standard M0 model and to the mutation-selection model of Yang and Nielsen (2008) using the AIC. Our new model provided significantly better fit in approximately 85% of the cases considered for the basic M0 model and in approximately 25% of the cases for the M0 model with estimated codon frequencies, but only in a few cases when the mutation-selection model was considered. However, our model includes a parameter that can be interpreted as a measure of the rate of protein production, and the estimates of this parameter were highly correlated with an independent measure of protein production for the yeast genes considered here. Finally, we found that in some cases the new model led to the preference of a different phylogeny for a subset of the genes considered, indicating that substitution model choice may have an impact on the estimated phylogeny.

Cost-Effective Culturing ofGalleria mellonellaandTenebrioMolitor and Entomopathogenic Nematode Production in Various Hosts

Wax moth larvae (Galleria mellonella L.) and yellow mealworm larvae (Tenebrio molitor L.) were reared on five different diets respectively, to determine which diet resulted in the highest increase in insect larval weight. Wax moth eggs were placed on each diet and larvae that developed therefrom were weighed after 51 days. A diet containing 118 g wheat flour, 206 g wheat bran, 118 g milk powder, 88 g brewer's yeast, 24 g wax powder, 175 ml honey and 175 ml glycerol, produced the heaviest larvae, with an average weight of 0.19 g per larva. Mealworms were weighed 62 days after adult beetles were placed on the various diets. The heaviest larvae were produced on a diet consisting of wheat bran only, with each larva weighing, on average, 0.0154 g. Nematode production of Heterorhabditis zealandica and H. bacteriophora using wax moth, mealworm, codling moth (Cydia pomonella) and false codling moth (Thaumatotibia leucotreta) larvae were determined, as well as was the correlation between the weight of the host larvae and that of the nematode progeny produced. Wax moth larvae produced the highest number of H. zealandica and H. bacteriophora per g of host. The mean number of H. zealandica and H. bacteriophora infective juveniles produced were 1 459 205 and 1 898 512, respectively, per g of host. The mean number of H. zealandica produced per g of codling moth and false codling moth larvae was 57 582 and 192 867, respectively. Lower mean numbers were produced for codling moth and false codling moth larvae when using H. bacteriophora, with 39 653 and 97 652 nematodes produced per g of the respective hosts. A significant positive linear relationship existed between weight of wax moth larvae and that of mealworm and the number of nematodes produced. Using frozen hosts of wax moth larvae and mealworm, comparable reproduction of nematodes was only found with mealworm.

Increase of fermentative activity of brewing yeast using zinc nanoaquachelate

The results of investigating the metal nanoaquachelate effect on the fermentative energy of brewing bottom yeast Saccharomycescerevisiae race - 11 were presented.To improve the fermentative activity of yeast mentioned above, zinc nanoaquachelate in an amount of 0.10-0.30 mg/dm3, in increments of 0.10 was used during the main fermentation of beer wort.As a result of the research using brewing yeast S. cerevisiae race - 11, it was found that adding zinc nanoaquachelate in an amount of 0.10 mg/dm3 in beer wort improves the fermentative activity, and the amount of the released carbon dioxide was 16. 7 % higher than in the fermentation of pure malt wort. The content of visible extract in the young beer on the seventh day of fermentation was 15.1 % higher compared with the control, pure malt wort.

Oral Intake of Carboxymethyl-Glucan (CM-G) from Yeast (Saccharomyces uvarum) Reduces Malondialdehyde Levels in Healthy Men.

Carboxymethyl-glucan (CM-G) is a water-soluble derivative of β(1→3)(1→6) glucan, a well-known immunostimulant and antioxidant compound. In this experimental, randomized and placebo-controlled study, the effects of oral CM-G intake over a 60-day period on the peripheral blood, cholesterol, glycemic index and malondialdehyde (MDA) levels of healthy men was assessed. The CM-G was obtained from spent brewer’s yeast (S. uvarum) with DS 0.8 and molecular weight of 2.2 × 105 Da. Following CM-G administration, no changes were observed in red and white blood cell, hematocrit, hemoglobin and platelet counts, or in cholesterol and glycemic indices. After 30 days of CM-G administration, the MDA levels decreased significantly (p ≤ 0.05) in men receiving CM-G. The results showed for the first time that CM-G may act as an adjuvant in preventing oxidative damage in healthy humans.

Estimation of the novel antipyretic, anti-inflammatory, antinociceptive and antihyperlipidemic effects of silymarin in Albino rats and mice

ObjectiveTo evaluate the other pharmacological actions of silymarin in Albino rats and mice such as antipyretic, anti-inflammatory, antinociceptive and antihyperlipidemic effects. MethodsRats were injected intramuscularly with pyrogenic dose of brewer's yeast for the antipyretic test of silymarin. Another group of rats injected with 0.1 mL of 1% carrageenan solution in saline at the subplanter area of the right hind paw for the anti-inflammatory test of silymarin. Another group of mice tested by hot plate method for determination of antinociceptive effect of silymarin. Hyperlipidemia was induced using high fat diet for 2 months to estimate the antihyperlipidemic activity of silymarin. ResultsSilymarin showed a significant antipyretic effect of both doses (50 and 100 mg/kg) compared with control untreated group. Moreover, silymarin elucidated a significant anti-inflammatory effect of both doses reflected on the decrease of the rat paw edema every hour interval for 4 h after administration in comparison with control positive group. By the same taken, both doses of silymarine revealed a significant antinociceptive action in hot plate method at 30 and 60 min post administration. Besides, it lowered significantly the serum levels of prostaglandin E2, tumor necrosis factor alpha and interleukin 1 beta after 2 h of silymarin administration in carrageenan induced rat paw edema besides the significant decrease of total cholesterol, triglycerides, low density lipoprotein and significantly elevated high density lipoprotein after 2 weeks of silymarin administration. ConclusionsThese outcomes delivered a new vision into the possible pharmacological mechanisms by which silymarin advances antipyretic, anti-inflammatory, antinociceptive and antihyperlipidemic effects.

Anti-inflammatory Activities of Total Leaf Extracts of Ficus sycomorus L. (Moraceae) used in Traditional Medicine in the Treatment of Sickle Cell Disease

Background: This study has been carried out to evaluate the in vivo anti-inflammatory, analgesic and anti-pyretic effects of an aqueous decoction and ethanol extract (95%) of Ficus sycomorus leaves. Methods: The anti-inflammatory effect was evaluated by the carrageenan-induced mice paw oedema model. The non-morphine type analgesic effect was evaluated trough acetic acid-induced writhing test. The morphine type analgesic activity was tested by mouse tail–flick test. The anti-pyretic activity was tested by induced hyperthermia in mice with brewer's yeast. Data analysis used the one way ANOVA test. Results: The anti-inflammatory effects of the two extracts, at doses of 300 and 500 mg/kg b.w., were dose dependent and comparable to those of the reference controls, indomethacin (1 mg/kg b.w.) and hydrocortisone (10 mg/kg b.w.). At the same dose, the analgesic effect of the ethanol extract on abdominal writhings induced by acetic acid, was comparable to those Lysine acetylsalicylate (LAS, 300 mg/kg b.w) and hydrocortisone (10 mg/kg b.w.) used as controls. As for the morphine type analgesic effects of the two extracts tested at doses of 300 and 500 mg / kg both were significantly higher in comparison with the blank control (p Key words: Anti-inflammatory, Analgesic, Antipyretic, Antinociceptive, Ficus sycomorus, Sickle cell disease.