Search Results (42)

The market for probiotic foods has grown significantly in recent years. Some microorganisms isolated from food fermentations, mainly lactic acid bacteria (LAB) and yeasts, may have probiotic potential. During the fermentation of cocoa and coffee, a plethora of microorganisms are involved, including yeasts and lactic acid bacteria (LAB), several of which may have probiotic potential. For this reason, this study aimed to overview the probiotic potential of some LAB and yeasts isolated from these fermentation processes. For this purpose, a search was conducted in several specialized databases (Google Scholar, PubMed, ScienceDirect, and Scopus). As a result of this search, some strains of LAB and yeasts from cocoa were found to be potentially probiotic, with characteristics like those of commercial probiotic strains. The LAB genera that showed the most substantial probiotic potential were Lactiplantibacillus, Limosilactobacillus, and Lactococcus, while for yeasts, it was Saccharomyces and Pichia. Full article

The use of probiotics has been gaining popularity in terms of inclusion into human diets over recent years. Based on properties exerted by these organisms, several benefits have been elucidated and conferred to the host. Bacteria have been more commonly used in probiotic preparations compared to yeast candidates; however, yeast exhibit several beneficial properties, such as the prevention and treatment of diarrhea, the production of antimicrobial agents, the prevention of pathogen adherence to intestinal sites, the maintenance of microbial balance, the modulation of the immune system, antibiotic resistance, amongst others. Saccharomyces boulardii is by far the most studied strain; however, the potential for the use of other yeast candidates, such as Kluyveromyces lactis and Debaryomyces hansenii, amongst others, have also been evaluated in this review. Furthermore, a special focus has been made regarding the production considerations for yeast-based probiotics and their formulation into different delivery formats. When drafting this review, evidence suggests that the use of yeasts, both wild-type and genetically modified candidates, can extend beyond gut health to support skin, the respiratory system, and overall immune health. Hence, this review explores the potential of yeast probiotics as a safe, effective strategy for preventative health in humans, highlighting their mechanisms of action, clinical applications, and production considerations. Full article

The increasing evidence regarding biological effects of exposure to an extremely low frequency magnetic field is of utmost interest not only to the scientific community, but also to legislative bodies and the public. However, the research in this field is full of controversial and inconsistent results, originated from a lack of widely acceptable physical mechanisms that could sufficiently describe the principle of such a field’s action. This experimental study addresses and points to possible sources of ambiguities via investigation of the ion parametric resonance mechanism at 50 Hz frequency. The chosen methodology incorporates exposure of the Saccharomyces cerevisiae yeast strain based on an established exposure protocol with special attention to the measurement of an applied time-varying magnetic field corresponding to the ion parametric resonance requirements. Subsequently, the differences in cell growth as a reaction to changes in magnetic flux density are evaluated and statistically analyzed. It is found that fluctuations in the magnetic field within the exposure setup need to be addressed properly, since this could have an impact on replication of the experiments and reliability of the results. Furthermore, comparison of two independently performed sets of 10 experiments showed statistically significant effects even in conditions that did not fulfill the requirements of the resonance theory, putting the validity and practical application of the ion parametric resonance model into question. Full article

The microbial terroir is an indispensable part of the terroir panorama, and can improve wine quality with special characteristics. In this study, eight autochthonous yeasts (Saccharomyces cerevisiae), selected in Huailai country, China, were trailed in small-scale and pilot fermentations for both white (Riesling and Sémillon) and red (Cabernet Sauvignon and Syrah) wines and evaluated by GC-MS analysis and the rate-all-that-apply (RATA) method. Compared to commercial yeast strains, the indigenous yeasts were able to produce higher concentrations of ethyl esters and fatty acid ethyl esters, and higher alcohol, resulting in higher odor activity values of fruity, floral attributes. Marked varietal effects were observed in the pilot fermentation, but yeast strains exerted a noticeable impact in modulating wine aroma and sensory profile. Overall, indigenous yeast could produce more preferred aroma compounds and sensory characteristics for both white and red wines, demonstrating the potential for improving wine quality and regional characteristics. Full article

Among many methods to produce low/no-alcohol beers, using special yeasts has gained a substantial interest in the brewing industry. This approach relies on the fact that many non-Saccharomyces yeasts do not utilize maltose, which is the main sugar found in brewer’s wort. Additionally, these yeasts may allow the production of a beer with unique sensory characteristics. The aim of the study was to evaluate the potential of 18 non-Saccharomyces yeast strains in the production of low-alcohol beer. As a control strain, S. cerevisiae US-05 was used. The study consisted of two parts: microbiological evaluation and small-scale fermentations. In the microbiological part, ability to ferment sugars found in a wort, resistance to stress factors, phenolic off-flavor production, and enzymatic activities of β-glucosidase and β-lyase were evaluated. In the second part of the study, yeasts were used to produce a beer from 9.3 °Plato wort. During the fermentation, its dynamics was analyzed. The obtained beers were analyzed regarding their alcohol content, pH, acidity, and color. All of the evaluated strains produced low levels of alcohol. Two of the evaluated strains were characterized by especially high β-glucosidase activity. Based on the obtained results, six of the evaluated strains are promising in brewing. Full article

Yeasts are gaining increasing attention for their potential health benefits as probiotics in recent years. Researchers are actively searching for new yeast strains with probiotic properties (i.e, Debaryomyces hansenii; Kluyveromyces marxianus; Yarrowia lipolytica; Pichia hudriavzevii; and Torulaspora delbrueckii) from various sources, including traditional fermented foods, the human gut, and the environment. This exploration is expanding the pool of potential probiotic yeasts beyond the well-studied Saccharomyces boulardii. Research suggests that specific yeast strains possess properties that could be beneficial for managing conditions like inflammatory bowel disease, irritable bowel syndrome, skin disorders, and allergies. Additionally, probiotic yeasts may compete with pathogenic bacteria for adhesion sites and nutrients, thereby inhibiting their growth and colonization. They might also produce antimicrobial compounds that directly eliminate harmful bacteria. To achieve these goals, the approach that uses probiotics for human health is changing. Next-generation yeast probiotics are emerging as a powerful new approach in the field of live biotherapeutics. By using genetic engineering, scientists are able to equip these tools with specialized capabilities. However, most research on these probiotic yeasts is still in its early stages, and more clinical trials are needed to confirm their efficacy and safety for various health conditions. This review could provide a brief overview of the situation in this field. Full article

Changing consumer preferences and increasing demands require adjustments in brewery operations and beer production methods. Recent trends indicate a marked decline in interest in high-alcohol beers and an increasing demand for low- and no-alcohol alternatives. The aim of this study was to evaluate and compare the volatile compound profiles produced by Saccharomyces cerevisiae var. chevalieri, a yeast strain specifically developed for non-alcoholic beer production, with a reference sample fermented with a standard Saccharomyces cerevisiae US-05 strain. Two mashing profiles were compared (with and without saccharification pause). The wort obtained was fermented with and without hops. The chemical composition and aroma compounds of the resulting beers were analysed using different chromatographic techniques (HPLC, GC-FID, GC-MS and CG-O). The modification of the mashing profile helped to obtain wort with about 50% lower maltose content. A lower FAN (free amino nitrogen) content was also observed, but this did not affect the fermentation process. Beers fermented with the Saccharomyces cerevisiae var. chevalieri strain had an average alcohol content of 0.5–0.8% v/v. This strain consumed about 25% of the available maltose. The resulting beers were dominated by fruity, floral and herbal aromas. In addition, beers fermented with a non-alcoholic beer strain scored highest in the sensory analysis. Full article

Innovation in the beer market focuses on research into the different ingredients that make up this popular and sought-after beverage. Some of these innovations have focused on the use of autochthonous ingredients, which bring added value to products, reduce production costs and environmental impact, and provide beers with special organoleptic characteristics. This study focuses on the use of autochthonous ingredients from the Community of Madrid and the design of four recipes that are suited to these ingredients and consumer demand. In terms of the ingredients used, the micromalting of barley grown in the CM was carried out, while hops (Cascade variety for bittering hops and wild hops Rayo verde Tajuña and Torreta Tajuña for aroma) and yeast strains (Saccharomyces cerevisiae G 520 and G 354) were selected from previous studies, which were also sourced from the CM. For the barley malt, parameters such as protein content were determined, which was at the maximum limit but did not affect the final quality of the beers. The content of α- and β-acids in the hops was also determined, being higher in the Cascade variety. Different physicochemical analyses (GC, aromatic compounds, bitterness, colour, SO₂, polyphenols, and antioxidant capacity) were carried out to determine the quality of the beers obtained from the four recipes designed, as well as tastings by a panel of experts and consumers. Finally, two recipes were rated the best by a panel of experts and consumers, where the cereal, hop, and fruit flavours stood out for their aromatic profile. Full article

Yeast is a powerful bioflavoring platform, suitable to confer special character and complexity to beer aroma. Enhancing yeast bioflavoring represents a chance for the brewing production chain to diversify its product portfolio and to increase environmental sustainability in the era of climate change. In flavor compound metabolism, multiple genes encoding biosynthetic enzymes and the related regulatory factors are still poorly known, but significant advances have been recently made to dissect gene contribution in flavor molecule production. Furthermore, causative mutations responsible for the huge strain diversity in yeast bioflavoring aptitude have been recently disclosed. This review covers the most recent advances in the genetics of yeast bioflavoring, with special regards to higher alcohols, esters, monoterpene alcohols, thiols, and phenolic derivatives of hydroxycinnamic acids. We also critically discussed the most significant strategies to enhance yeast bioflavoring, including bioprospecting for novel Saccharomyces and non-Saccharomyces strains, whole-genome engineering, and metabolic engineering. Full article

Oxidoreductase (OXR) enzymes are in high demand for biocatalytic applications in the food industry and cosmetics (glucose oxidase (GOx) and cellobiose dehydrogenase (CDH)), bioremediations (horseradish peroxidase (HRP) and laccase (LAC)), and medicine for biosensors and miniature biofuel cells (GOx, CDH, LAC, and HRP). They can be used in a soluble form and/or within the yeast cell walls expressed as chimeras on the surface of yeast cells (YSD), such as P. pastoris and S. cerevisiae. However, most of the current studies suffer from either low yield for soluble enzyme expression or low enzyme activity when expressed as chimeric proteins using YSD. This is always the case in studies dealing with the heterologous expression of oxidoreductase enzymes, since there is a requirement not only for multiple OXR gene integrations into the yeast genome (super transformations), and codon optimization, but also very careful design of fermentation media composition and fermentation conditions during expression due to the need for transition metals (copper and iron) and metabolic precursors of FAD and heme. Therefore, scientists are still trying to find the optimal formula using the above-mentioned approaches; most recently, researcher started using protein engineering and directed evolution to increase in the yield of recombinant enzyme production. In this review article, we will cover all the current state-of-the-art technologies and most recent advances in the field that yielded a high expression level for some of these enzymes in specially designed expression/fermentation systems. We will also tackle and discuss new possibilities for further increases in fermentation yield using cutting-edge technologies such as directed evolution, protein and strain engineering, high-throughput screening methods based on in vitro compartmentalization, flow cytometry, and microfluidics. Full article

Recent interest in the special beer category has encouraged the search for novel brewing materials, including new ingredients and novel yeast strains, in order to differentiate the finished products. The aim of this work was to select non-brewing S. cerevisiae strains for the production of a fruit beer with raspberry. The in vitro tests and the wort fermentations allowed the selection of two sourdough S. cerevisiae strains, showing high maltose and maltotriose consumption, high ethanol production, and high viability. Fruit beers (FB) and control beers (CB) without raspberries were prepared. Fruit addition accelerated sugar consumption (7 days compared to 13 days) and increased ethanol and glycerol production by yeasts. Raspberry addition and the inoculated yeast strongly affected the aroma profile of beers. FB samples showed a higher amount of volatile organic compounds (VOCs); the most represented classes were alcohols, followed by esters and acids. FB inoculated by the selected S. cerevisiae SD12 showed the highest VOCs concentration (507.33 mg/L). Results highlighted the possible application of sourdough yeast strains for the brewing process, which, combined with raspberry addition, can be exploited for the production of beers with enhanced aromatic features and suitable chemical properties. Full article

Maize is one of the most important food and feed crops in China due to the high demand for its use by both humans and animals. The Huang-Huai-Hai region is a major maize cultivation area in China, and the special cropping rotation system of wheat and maize requires a suitable reproductive period for maize. The AUX/IAA and ARF transcription factors are two key genes that regulate auxin signals in plants, which play an important role during the process of auxin regulation in plant growth and development. In this study, we obtained two overexpressed lines of ZmIAA29 belonging to the AUX/IAA transcription factor family. Compared with the Wide type, the overexpressed strains of ZmIAA29 were significantly regulated in maize during the flowering time and had increased ear weight. Moreover, ZmIAA29 was assayed via the yeast two-hybrid and BiLUC systems for interaction, and the results showed that ZmIAA29 interacted with several ZmARF transcription factors. Furthermore, RNA-seq and DAP-seq analysis revealed that ZmIAA29 regulates maize growth and development by influencing pathways such as those for plant signal transduction and the key genes related to maize flowering. Taken together, our results suggest that ZmIAA29 plays a key role in the development of maize flowering. This study provides new insight for better understanding the combined regulation of the AUX/IAA and ARF transcription factors during flowering time in maize. Full article

The concept of fastidious microorganisms currently found in scientific literature is mainly related to the difficulty of isolating/culturing/preserving bacteria. Eukaryotes are investigated much less in this respect, although they represent a fundamental part of the microbial world. Furthermore, not only isolation, but also identification and culturing (in the perspective of long-term preservation) should be considered key aspects often impacting on the study of fastidious microorganisms, especially in terms of preservation in culture collections and biotechnological exploitation. The present review aimed to investigate the current state of the art on fastidious eukaryotes, with special emphasis on the efforts to improve their isolation, identification, culturing and long-term preservation in culture collections practices. A few case studies focused on some fastidious eukaryotic microorganisms (including possible customized solutions to overcome specific issues) are also presented: isolation and preservation of slow-growing fungi, culturing of Haematococcus lacustris, isolation of unialgal strains of Cyanidiophytina (Rhodophyta), identification of Metschnikowia pulcherrima clade yeasts, isolation and preservation of Pyricularia species, preservation of Halophytophtora spp. Full article

The simplest way to eliminate microorganisms in the must/wine is through sulfuration, as it allows the introduction of pure yeast varieties into the must, which guarantees a high-quality wine. However, sulfur is an allergen, and an increasing number of people are developing allergies to it. Therefore, alternative methods for microbiological stabilization of must and wine are being sought. Consequently, the aim of the experiment was to evaluate the effectiveness of ionizing radiation in eliminating microorganisms in must. The sensitivity of wine yeasts, Saccharomyces cerevisiae, S. cerevisiae var. bayanus, Brettanomyces bruxellensis, and wild yeasts to ionizing radiation was com-pared. The effects of these yeasts on wine chemistry and quality were also determined. Ionizing radiation eliminates yeast in wine. A dose of 2.5 kGy reduced the amount of yeast by more than 90% without reducing the quality of the wine. However, higher doses of radiation worsened the organoleptic properties of the wine. The breed of yeast used has a very strong influence on the quality of the wine. It is justifiable to use commercial yeast breeds to obtain standard-quality wine. The use of special strains, e.g., B. bruxellensis, is also justified when aiming to obtain a unique product during vinification. This wine was reminiscent of wine produced with wild yeast.. The wine fermented with wild yeast had a very poor chemical composition, which negatively affected its taste and aroma. The high content of 2-methylbutanol and 3-methylbutanol caused the wine to have a nail polish remover smell. Full article

Carotenoids are lipid-soluble compounds that are present in nature, including plants and microorganisms such as fungi, certain bacteria, and algae. In fungi, they are widely present in almost all taxonomic classifications. Fungal carotenoids have gained special attention due to their biochemistry and the genetics of their synthetic pathway. The antioxidant potential of carotenoids may help fungi survive longer in their natural environment. Carotenoids may be produced in greater quantities using biotechnological methods than by chemical synthesis or plant extraction. The initial focus of this review is on industrially important carotenoids in the most advanced fungal and yeast strains, with a brief description of their taxonomic classification. Biotechnology has long been regarded as the most suitable alternative way of producing natural pigment from microbes due to their immense capacity to accumulate these pigments. So, this review mainly presents the recent progress in the genetic modification of native and non-native producers to modify the carotenoid biosynthetic pathway for enhanced carotenoid production, as well as factors affecting carotenoid biosynthesis in fungal strains and yeast, and proposes various extraction methods to obtain high yields of carotenoids in an attempt to find suitable greener extraction methods. Finally, a brief description of the challenges regarding the commercialization of these fungal carotenoids and the solution is also given. Full article