Search Results (146)

Olive mill wastewater (OMWW) is a highly polluting agro-industrial effluent characterized by elevated organic load, low pH, and high concentrations of phenolic compounds responsible for its phytotoxicity and dark coloration. In this study, 41 non-conventional yeast strains belonging to the University of Basilicata Yeast Collection (UBYC), were tested for both the oleaginous potential traits and OMWW detoxification capacity in comparison to two commercial oleaginous controls, Yarrowia lipolytica ATCC 46483 and Lipomyces tetrasporus Li-0407. Primary screening in synthetic medium under nitrogen-limited conditions revealed widespread intracellular lipid accumulation. Quantitative analysis showed lipid contents above 20% (w/w) in some strains, with Candida tropicalis AII122 (33.3%) and Pichia manshurica ML-3 (29.4%) exhibiting the highest values in synthetic medium. The cultivation of eight selected strains in synthetic medium supplemented with 15% (v/v) of OMWW reduced intracellular lipid accumulation, with the highest value of 6.48% for the 2R1 strain. Levels of phenol reduction and color removal were highly different among all the analyzed strains, and C. tropicalis AII122 achieved the highest phenolic reduction and decolorization ability. These findings demonstrate that indigenous non-conventional yeasts represent a source of natural biodiversity, supporting sustainable waste valorization strategies based on the use of selected microorganisms within a circular bioeconomy framework. Full article

Proteases are key biocatalysts widely applied in the food, pharmaceutical, detergent, and environmental industries. One of the most costly steps in large-scale enzyme production is the preparation of the culture medium, making agro-industrial wastes attractive as low-cost nutrient sources and potential inducers. The non-conventional yeast Yarrowia lipolytica stands out in bioprocess engineering due to its high secretion capacity, GRAS status, and ability to metabolize diverse industrial residues. In this study, Brazilian agro-industrial by-products, namely Corn steep liquor (CSL), brewer’s yeast residue (BYR), and okara, were evaluated as alternative nitrogen sources for protease production by Y. lipolytica IMUFRJ 50678. Enzyme activity was quantified by the azocasein method at optimized conditions (40 °C, 40 min, pH 5 and 8). After an initial exploratory screening (n = 1), brewer’s yeast residue (BYR) and okara were identified as promising candidates for protease production. These preliminary findings guided subsequent experiments performed in biological triplicate (n = 3), which confirmed the reproducibility and comparative performance of these substrates, showing higher acid protease (AXP) activity in the BYR medium ((5.4 ± 0.3) U/mL), whereas alkaline protease (AEP) activities were comparable between the BYR ((8.4 ± 0.6) U/mL) and okara ((7.5 ± 0.9) U/mL) media. CSL was associated with higher lipase activity ((11.7 ± 0.9) × 10³ U/L), while esterase activity was higher in the BYR medium. These findings indicate that agro-industrial residues, particularly BYR and okara, can serve as effective nitrogen sources for protease production by Y. lipolytica IMUFRJ 50678, supporting their use in waste valorization and sustainable bioprocesses. Full article

Alcoholic fermentation in winemaking is a complex bioprocess governed by physicochemical parameters such as temperature, density, pH, CO₂ and redox potential, which critically affect yeast metabolism and wine quality. This review provides an integrated analysis of fermentative dynamics and emerging sensorization technologies, highlighting how their combined implementation enables real-time monitoring and advanced control in precision enology. Advances in conventional physicochemical sensors, spectroscopic techniques (NIR/MIR/UV-Vis) and non-conventional devices (e-noses, electronic tongues) integrated into IoT platforms enable continuous data acquisition, overcoming traditional manual sampling limitations. Predictive modeling, including kinetic models, machine learning approaches (e.g., Random Forest, XGBoost) and model predictive control (MPC/NMPC), supports anomaly detection, optimization of enological interventions and energy-efficient thermal management, while virtual sensors based on Kalman filters improve the estimation of non-measurable states (e.g., biomass, ethanol kinetics). Despite current challenges in calibration and interoperability, these innovations foster sustainable and reproducible winemaking under climate variability and pave the way for digital twins and semi-autonomous fermentation systems. Full article

Oleaginous yeasts are promising microbial platforms for lipid production from non-conventional carbon sources; however, acetate utilization is frequently constrained by physiological limitations associated with culture pH. In this study, acetate utilization, biomass formation, and lipid production by Lipomyces starkeyi were investigated under flask and fed-batch cultivation to evaluate the influence of culture pH and pH control strategy. Statistically supported flask-scale experiments demonstrated that acetate concentration and cultivation time significantly affected acetate consumption, biomass formation, volumetric lipid concentration, and culture pH, with excessive acetate loading resulting in culture alkalization, incomplete substrate utilization, and reduced process performance. Although volumetric lipid concentration increased with increasing acetate concentration, lipid content and fatty acid composition remained unchanged, indicating that enhanced lipid production was primarily attributable to increased biomass formation rather than to changes in lipid biosynthesis. Fed-batch cultivation under different pH-control strategies provided qualitative insights into the relationships among pH regulation, acetate availability, and lipid accumulation under controlled fermentation conditions. While lipid accumulation was observed under both HCl-based and acetic acid-based pH control, differences in pH stability and cumulative acetate availability were associated with distinct patterns of lipid production. Collectively, these results identify culture pH as a critical physiological parameter influencing acetate utilization and lipid accumulation in L. starkeyi and suggest that coordinated pH control and carbon feeding strategies may improve the robustness of acetate-based lipid production processes. Further replicated fed-batch studies will be required to quantitatively validate these trends and support industrial applications. Full article

The craft beer market is continually expanding, driven by the consumers’ demand for product diversification, which leads to innovation in the brewing industry. While traditional brewing focuses on consistency and high-volume efficiency using standard yeasts, craft brewing prioritizes small-batch experimentation and flavor complexity. Traditionally, Saccharomyces cerevisiae (Ale beer) and Saccharomyces pastorianus (Lager beer) yeast are used in brewing. The craft brewing revolution introduced the use of non-conventional yeast. These yeasts possess distinct technological characteristics compared to commercial starters, such as a richer enzyme profile. This biological diversity produces beers with novel, complex aroma profiles, and opens exciting avenues for flavor creation. Recently, non-alcoholic beer and low-alcoholic beer (NABLAB), and functional beer have become the new horizons for the application of non-conventional yeasts. In recent years, the brewing potential of these alternative yeasts has been extensively explored. However, some aspects relating to the interactions between yeast and raw materials precursors involved in the aroma of the final beer, and the management of yeasts in fermentation, remain unexplored. This review systematically outlines the various innovative ways in which non-conventional yeasts are applied in brewing, including healthier beer. Here, we explore how these yeasts can foster innovation in the beer sector and provide the possibility for sustainable development in contemporary brewing. Full article

Microbial bioconversion of agro-industrial by-products into high-value-added metabolites such as polysaccharides or lipids serves a dual purpose: mitigating environmental pollution through waste reduction and supporting the development of novel bioproducts. In this study, a non-conventional, poorly studied Cryptococcus albidus strain was initially assessed for its ability to grow on semi-defined media containing lactose, glycerol, or glucose under three distinct nitrogen availability conditions at C/N equal to 20, 80, and 160 mol/mol in shake flask cultures. The goal was to evaluate biomass production and synthesis of valuable metabolites under these conditions. C. albidus demonstrated robust growth on all commercial carbon sources, particularly under nitrogen-rich conditions, producing more than 25.0 g/L of microbial biomass with a high intracellular polysaccharide content (>45%, w/w). Additionally, mannitol production was detected in cultures with glycerol and glucose (9.1 and 13.1 g/L, respectively), especially after nitrogen depletion. Subsequently, C. albidus and a Cutaneotrichosporon curvatus strain were batch-cultivated using pretreated secondary cheese whey (SCW) as a carbon-rich waste substrate. When cultivated on SCW, both yeast strains partially metabolized lactose and produced polysaccharide-rich biomass, dominated by β-glucans (>29% of total biomass), compounds known for their functional and bioactive properties. The cellular polysaccharides (cPS extracted from C. albidus exhibited cytotoxic effects against cancer cells, suggesting their potential use as biological response modifiers. In contrast, the cPS from C. curvatus did not affect cell viability, indicating their promise as ingredients for applications in the food, feed, pharmaceutical, or cosmetic sectors. Full article

The development of non-alcoholic beer (NAB) with health benefits, using non-conventional potential probiotic yeasts, offers an interesting alternative to standard NAB brewing strategies. In this study, potential probiotic non-Saccharomyces yeasts Pichia manshurica, Kluyveromyces lactis, and Kluyveromyces marxianus, along with commercial probiotic yeast Saccharomyces boulardii, were characterised and tested for functional NAB production, whereas P. manshurica was used in NAB production for the first time. Growth and viability were assessed across a range of temperatures, pH, and iso-α-bitter acids. The tested yeasts withstood conditions typical of the beer matrix and human digestive tract and had a positive phenolic off-flavour phenotype. Two strains, K. lactis and K. marxianus, showed strong β-glucosidase activity, which may enhance beverage aroma complexity. Ethanol levels in beers fermented with non-Saccharomyces yeasts remained below the NAB limit (≤0.5% v/v). An analysis of volatile organic compound profiles revealed the potential of these yeasts to produce higher alcohols and esters valuable from a brewer’s perspective. This study provides valuable insight into novel probiotic fermentations and the potential application of unconventional yeasts in functional, aromatic, and health-oriented non-alcoholic beverages. Full article

In response to the growing interest in less conventional alcoholic beverages, this study aimed to identify novel yeast strains suitable for sake production, with a focus on their potential application in bioflavouring. Commercially available strains of bottom-fermenting brewing yeasts (Saccharomyces pastorianus), a cryotolerant wine yeast (Saccharomyces bayanus), and a wild wine yeast (Torulaspora delbrueckii) were evaluated. The quality characteristics of sake obtained using non-conventional yeasts were compared with sake produced using Saccharomyces cerevisiae K7, one of the most commonly used strains in sake brewing. Sake made with non-conventional yeasts exhibited differences in fermentation kinetics, chemical composition, and sensory properties. Wine yeasts produced sake with the most favorable ester profile, markedly distinct from those obtained with other yeast strains used in the study. Compared to the conventional strain, the concentrations of the key contributors to the fruity/floral aroma, namely 3-methylbutyl acetate and ethyl hexanoate, in sake produced with S. bayanus were higher by 249.5% and 199.3%, respectively. The wine yeast S. bayanus may be considered the most promising strain for sake production due to its ability to generate elevated levels of volatile aroma compounds associated with Ginjo-ka characteristics, as well as its effectiveness in supporting a consistent and efficient alcoholic fermentation process. Full article

Although beer fermentation has traditionally been carried out with Saccharomyces, the boom in craft brewing has led to the use of non-conventional yeast species for beer production. This group also includes non-Saccharomyces starters, which are commonly used in winemaking and which have different technological characteristics compared to standard representatives of the Saccharomyces genus. One of the important characteristics of the non-Saccharomyces group is the richer enzyme profile, which leads to the production of beverages with different taste and aroma profiles. The aim of this study was to investigate sweet and hopped wort fermentation with seven strains of active dry non-conventional yeasts of Lachancea spp., Metschnikowia spp., Torulaspora spp. and a mixed culture of Saccharomyces cerevisiae and Torulaspora delbrueckii. One ale and one lager active dry yeast strain were used as control strains. The extract consumption, ethanol production, degree of fermentation, pH drop, as well as the yeast secondary metabolites formed by the yeast (higher alcohols, esters and aldehydes) in sweet and hopped wort were investigated. The results indicated that all of the studied types of non-conventional yeasts have serious potential for use in beer production in order to obtain new beer styles. For the purposes of this study, statistical methods, principle component analysis (PCA) and correlation analysis were used, thus establishing the difference in the fermentation kinetics of the growth in the studied species in sweet and hopped wort. It was found that hopping had a significant influence on the fermentation kinetics of some of the species, which was probably due to the inhibitory effect of the iso-alpha-acids of hops. Directions for future research with the studied yeast species in beer production are presented. Full article

CRISPR technology, which is derived from the bacterial adaptive immune system, has transformed traditional genetic engineering techniques, made strain engineering significantly easier, and become a very versatile genome editing system that allows for precise, programmable modifications to a wide range of microbial genomes. The economies of fermentation-based manufacturing are changing because of its quick acceptance in both academic and industry labs. CRISPR processes have been used to modify industrially significant bacteria, including the lactic acid producers, Clostridium spp., Escherichia coli, and Corynebacterium glutamicum, in order to increase the yields of bioethanol, butanol, succinic acid, acetone, and polyhydroxyalkanoate precursors. CRISPR-mediated promoter engineering and single-step multiplex editing have improved inhibitor tolerance, raised ethanol titers, and allowed for the de novo synthesis of terpenoids, flavonoids, and recombinant vaccines in yeasts, especially Saccharomyces cerevisiae and emerging non-conventional species. While enzyme and biopharmaceutical manufacturing use CRISPR for quick strain optimization and glyco-engineering, food and beverage fermentations benefit from starter-culture customization for aroma, texture, and probiotic functionality. Off-target effects, cytotoxicity linked to Cas9, inefficient delivery in specific microorganisms, and regulatory ambiguities in commercial fermentation settings are some of the main challenges. This review provides an industry-specific summary of CRISPR–Cas9 applications in microbial fermentation and highlights technical developments, persisting challenges, and industrial advancements. Full article

Wine vinegar and wine are traditional Spanish products, obtained from grape must by alcoholic fermentation (wine) and subsequent acetification (vinegar). Although these are established products, there is great interest in the development of new products, particularly new vinegars, and among these, the possibility of vinegars containing gluconic acid stands out. Gluconic acid in vinegar, mainly produced by acetic acid bacteria (AAB), is positively valued by consumers. Its content depends on the availability of glucose in the base wine; however, this hexose is preferentially consumed by the indigenous yeast population which conducts the previous alcoholic fermentation. For this reason, the use of non-conventional fructophilic yeasts, which consume fructose rather than glucose, is required. In this work, we isolated, screened, and identified osmophilic and fructophilic non-Saccharomyces yeasts from sun-dried grape must and tested them under different fermentation conditions in synthetic and natural grape musts, in order to obtain a base wine with ethanol and glucose content for the development of new vinegars containing gluconic acid. The isolate of the species Starmerella lactis-condensi was found to be an ideal candidate due to its fructophilic and osmophilic features, which allowed for the production of a base wine with high ethanol (11% v/v) and glucose (up to 200 g/L) content from a natural concentrated must. In fresh must, inoculation with Starmerella lactis-condensi resulted in faster and preferential fructose consumption over glucose compared to the control. However, both sugars were completely consumed at the end of the alcoholic fermentation; therefore, new fermentation strategies should be tested in this type of must. Furthermore, this strain could be of interest in oenology due to its high glycerol yield and low volatile acid production during alcoholic fermentation. The use of this strain could allow for the production of new wines with unique metabolic profiles suitable for further vinegar production. Full article

Consumer demand for low-alcohol acidic beers is driving the use of non-conventional yeasts in the brewing process. In this study, the addition of mixed berries and fermentation with L. thermotolerans L31 are performed in crafting a low-alcohol acidic beer. Four different beers were brewed in the primary stage with either Saccharomyces cerevisiae or L. thermotolerans and with or without added berry mixture. Beer was fermented for 8 days at 20 °C, stored, and bottled. pH, density, alcoholic content, bitterness, and color of final beer were analyzed for all samples using analytical methods. Volatile compounds, anthocyanin content, and antioxidant activity were also evaluated. Sensory analysis was performed and correlated (PCA) with the analytical results. The obtained data indicated that beers brewed with L. thermotolerans were significantly more acidic and less bitter than S. cerevisiae beers. No difference in alcoholic content was found. Fruity aroma-associated compounds were present in L. thermotolerans beers, which correlated with the sensory analysis. Fruit beers were also redder and showed higher anthocyanin content and stronger antioxidant activity due to the presence of anthocyanins such as cyanidin, delphinidin, and malvidin from fruit, and other antioxidant compounds. Full article

In view of the growing global need for sustainable protein sources, this study explores the utilization of short-chain fatty acids into single-cell protein using the non-conventional yeast Cyberlindnera jadinii. Short-chain fatty acids can be sustainably produced via anaerobic digestion of organic waste, presenting a promising fermentation substrate for a circular bioeconomy. Cyberlindnera jadinii is demonstrated to be capable of growing on acetate, propionate and butyrate as both a carbon and energy source without strong inhibition. Bioprocess development was conducted in stirred tank bioreactors, where a fed-batch pH-stat bioprocess led to improved efficiency without substrate inhibition. The highest titer of 31.3 ± 1.0 g/L, rate of 0.67 ± 0.02 g/L/h and yield of 0.36 ± 0.01 g/g was achieved with propionate. The resulting biomass contained 41.3% crude protein, and 17.3% crude lipids with 81% unsaturated fatty acids. In contrast to acetate and butyrate, propionate as a substrate led to accumulation of 37% odd-chain fatty acids with titer, rate and yield of 1.74 ± 0.06 g/L, 0.037 ± 0.001 g/L/h and 0.020 ± 0.001 g/g. These findings confirm that short-chain fatty acids are viable fermentation substrates not only for single-cell protein, but also unsaturated and odd-chain fatty acid production with Cyberlindnera jadinii. Full article

The presence of various inhibitory compounds in lignocellulosic hydrolysates poses a significant challenge for bioethanol production, requiring yeasts with exceptional multistress tolerance. This study introduces the novel application and demonstrates the robust performance of the nonconventional yeast Saccharomycodes ludwigii APRE2 for efficient bioethanol production directly from undetoxified sugarcane bagasse hydrolysate (SBH) at 37 °C. This approach critically eliminates the need for the costly detoxification pretreatments often required in industrial processes. Initial experiments confirmed S. ludwigii APRE2’s capability to ferment undetoxified SBH. To optimize fermentation efficiency, a central composite design (CCD) approach was implemented. This statistical method identified the following precise optimal parameters: sugar concentration (143.95 g/L), diammonium phosphate (4.99 g/L), pH (4.98), yeast extract (8.94 g/L), and magnesium sulfate (2.22 g/L). Under these optimized conditions, impressive results were achieved: a maximum ethanol concentration of 38.11 g/L, productivity of 1.59 g/L·h, and yield of 0.45 g/g. Notably, the ethanol productivity and theoretical yield achieved by S. ludwigii APRE2 using this inhibitor-rich, undetoxified SBH (containing acetic acid, formic acid, furfural, and 5-(hydroxymethyl)furfural) were superior to those previously reported for other ethanologenic yeasts under similar challenging conditions. This research establishes S. ludwigii APRE2 as a highly promising and industrially viable candidate for sustainable bioethanol production from lignocellulosic biomass, with its key novelty being its superior performance on undetoxified feedstocks, potentially reducing overall production costs. Full article

Mannoproteins are structural components of the yeast cell wall exhibiting extensive functionality applicable to the food, feed, and medical industries. They are characterized mostly by immunostimulatory, prebiotic, antimicrobial, antibiofilm, antioxidant, and emulsifying properties. The bioactive properties of mannoproteins underscore their significance in functional food production, therapy, and animal husbandry. This review critically examines the literature on yeast mannoproteins, focusing on their chemical characteristics, biological activity, and potential applications. Considering gaps in the literature data regarding detailed chemical characterization and mechanisms of action of mannoproteins, future research should aim at precise structural analysis, particularly of mannoproteins derived from nonconventional yeast, to uncover new potential industrial and health applications. Full article