Yeast Culture Research Articles

Can the supplementation of autolyzed yeast (Saccharomyces cerevisiae) affect the diet digestibility, feeding behavior, levels of blood metabolites, and performance of Dorper × Santa Ines lambs finished in feedlot?

This study aimed to evaluate the effect of autolyzed yeast (obtained from culture of Saccharomyces cerevisiae in sugarcane derivatives) supplementation on diet digestibility, feeding behavior, levels of blood metabolites associated with protein and energy metabolism, and performance of Dorper × Santa Ines lambs finished in feedlot. Twenty-four non-castrated male lambs with an average age of 4months and a body weight (BW) of 19.49 ± 3.08kg were allocated to individual pens within a covered and elevated shed. The pens had a slatted floor without bedding suspended 1.8m above the ground, and an area of 1.5 m2. The trial was set out in a completely randomized design with two treatments and twelve replicates each. The treatments consisted of a basal diet without yeast products (Control) or with yeast culture (Yeast, RumenYeast® at 5g/animal/day). Lambs were fed ad libitum with a total mixed ration (TMR) composed of 400g/kg of dry matter (DM) of Tifton 85 hay (Cynodon spp.) and 600g/kg DM of concentrate feed, and contained 146g/kg DM of crude protein and 2.30 Mcal/kg DM of metabolizable energy. The experiment was conducted over 84days, with the first 14days serving as an adaptation period. The subsequent experimental period was divided into two phases to evaluate animal performance (Days 1-63) and DM digestibility (Days 64-70). The supplementation with autolyzed yeast did not affect rumen or fecal pH, the DM digestibility, as well as the feeding behavior of lambs (the time spent on feeding, rumination, water intake, and idleness activities). In addition, yeast supplementation did not alter the serum levels of albumin, creatinine, urea, or level of plasma glucose, resulting in similar animal performance compared to the Control group. The mean values for final BW, DM intake, average daily gain, and feed conversion ratio were 37.52kg, 1.051kg/day, 0.286kg/day, and 3.74kg DM/kg gain, respectively. In the conditions of this study, the supplementation of autolyzed yeast in TMR (5g/animal/day) does not affect diet digestibility, feeding behavior, blood metabolites, or performance of lambs finished in feedlot. Regarding that metabolic and performance lamb responses were not improved, the supplementation of autolyzed yeast at the tested dose is not recommended. However, it is important to note that markers related to immunity and inflammation were not evaluated in our work, and these should be considered in future studies.

Cost-effective production of kombucha bacterial cellulose by evaluating nutrient sources, quality assessment, and dyeing methods.

Kombucha is a popular fermented beverage that involves fermentation using a symbiotic culture of bacteria and yeast (SCOBY) and produces bacterial cellulose (BC). Carbon and nitrogen sources are essential in kombucha processing and BC production. However, studies on cost-effective BC production as an alternative source of leather have remained scarce. This study aimed to assess the effects of various nitrogen and carbon sources on the production of kombucha BC, investigate the qualities, and dye the product using natural colorant. Different nitrogen sources (such as black tea, white tea, and green tea) and carbon sources (honey, sugar cane, palm sugar, and brown sugar) were used to produce kombucha BC, as well as to appraise the product qualities, which were dyed using three distinct natural dyes (coffee, ginger, and sappan wood). The results revealed that different nitrogen and carbon sources produced different BC with different properties. Green tea (N-source) and palm sugar (C-source) containing medium produced a BC thickness of 0.194 ± 0.04mm with the highest tensile strength (24.42 ± 3.90g). Different dyes also result in the fabric having different colors: brownish yellow (coffee), yellowish orange (ginger), and red (sappan wood). All BC products showed color stability after 8months of storing at room temperature. In conclusion, effective BC production could use green tea and palm sugar as the best nitrogen and carbon sources, respectively. Dyed BC showed good visual quality and is promising for its eco-friendly and sustainable application in fashion products.

Optimizing Bacterial Protectant Composition to Enhance Baijiu Yeast Survival and Productivity During Spray Drying

The flavor substances produced by the division of baijiu yeast during the winemaking process often determine the quality of white wine, and the difficulty of storing and transporting high-quality baijiu yeast is a bottleneck that restricts the development of China’s baijiu industry. It is widely accepted that drying microorganisms such as baijiu yeast is the best way to improve its storage and transport performance. Spray drying, as one of the most widely used microbial drying processes, with a high efficiency and low cost, is the hot spot of current research in the field of microbial drying, but it has the inherent defect of a low drying survival rate. In order to address this inherent defect, the present study was carried out with a high-quality white wine yeast, Modified Sporidiobolus Johnsonii A (MSJA), as the target. Firstly, an orthogonal experiment, Steep Hill Climbing experiment, and response surface experiment were sequentially designed to optimize the type and amount of protective agent added in the spray-drying process of MSJA. Then, the effects of glutamyl transaminase (TGase) treatment on the drying process of MSJA were revealed with the help of advanced equipment, such as laser particle sizer, environmental scanning electron microscope (ESEM), and Fourier-transform infrared scanner (FTIR). The results showed that the addition of “TGase-treated soybean isolate protein (SPI) + lactic protein (LP)” as an in vitro bacterial protectant and “14.15% trehalose + 7.10% maltose + 14.04% sucrose” TGase treatment can promote the cross-linking of protective proteins, reduce the distance between MSJA bacteria and protective proteins, and increase the glass transition temperature to enhance the protective effect of protective proteins, so as to improve the survival rate of MSJA during spray drying.

Effects of combined Bacillus coagulans and Yeast fermentation culture on growth performance, plasma biochemical indices, intestinal morphology and microbial of broilers.

The favorable impacts of Bacillus coagulans or Yeast culture on broiler production performance and immune function have been acknowledged. However, the effects of the combined of them (BcYc) on the broilers remained unknown. Thus, the current research aimed to assess the effects of BcYc (at dosages of 0, 200, 300, and 400mg/kg) on growth performance, plasma biochemical indices, antioxidant capacity, and intestinal morphology and microbial composition in broilers. The results revealed that ①broilers receiving 300 and 400mg/kg of BcYc showed significantly higher body weights than the control group at 4d and 21d (P < 0.05). Additionally, when contrasted with the control group, the feed conversion ratio was significantly decreased in 300mg/kg group during 4 to 21d and in 400mg/kg group during 4 to 42d (P < 0.05). ②At 21d, the broilers supplemented with 300 and 400mg/kg of BcYc demonstrated significantly elevated levels of albumin (ALB), glutathione peroxidase activity (GSH-Px), total antioxidant capacity, and catalase activity than the group that not supplemented with BcYc (P < 0.05). At 42d, 400mg/kg group showed significantly higher ALB and total protein, and lower glutamic-pyruvic transaminase activity and malondialdehyde content in contrast to the control group (P < 0.05). Furthermore, at 42d, GSH-Px activity in all experimental groups showed significantly higher compared to the control group (P < 0.05). ③Nevertheless, no significant variation was observed neither in jejunum or duodenum morphology among all groups (P > 0.05). ④Adding 400mg/kg of BcYc led to a significantly higher Sobs index and a lower Simpson index (P < 0.05), and an extremely significantly raised in Shannon index (P < 0.01), while adding 300mg/kg of BcYc led to a significantly enhanced in Shannon index (P < 0.05). Additionally, supplementary BcYc significantly elevated the abundance of Firmicutes in phylum level, and Clostridia, Ruminococcus, Rikenella, Butyricicoccus and Eubacterium in genus level (P < 0.05). To sum up, supplementing BcYc at dosages of 400mg/kg to yellow-feathered broilers diet can help improve the growth performance, regulate plasma biochemical indicators, increase antioxidant capacity, and improve gut community composition.

Optogenetic control of horizontally acquired genes prevent stuck fermentations in yeast.

Nitrogen limitations in the grape must be the main cause of stuck fermentations during the winemaking process. In Saccharomyces cerevisiae, a genetic segment known as region A, which harbors 12 protein-coding genes, was acquired horizontally from a phylogenetically distant yeast species. This region is mainly present in the genome of wine yeast strains, carrying genes that have been associated with nitrogen utilization. Despite the putative importance of region A in yeast fermentation, its contribution to the fermentative process is largely unknown. In this work, we used a wine yeast strain to evaluate the contribution of region A to the fermentation process. To do this, we first sequenced the genome of the wine yeast strain using long-read sequencing and determined that region A is present in a single copy. We then implemented an optogenetic system in this wine yeast strain to precisely regulate the expression of each gene, generating a collection of 12 strains that allow for light-activated gene expression. To evaluate the role of these genes during fermentation, we assayed this collection using microculture and fermentation experiments in synthetic must with varying amounts of nitrogen concentration. Our results show that changes in gene expression for genes within this region can impact growth parameters and fermentation rate. We additionally found that the expression of various genes in region A is necessary to complete the fermentation process and prevent stuck fermentations under low nitrogen conditions. Altogether, our optogenetics-based approach demonstrates the importance of region A in completing fermentation under nitrogen-limited conditions.IMPORTANCEStuck fermentations due to limited nitrogen availability in grape must represent one of the main problems in the winemaking industry. Nitrogen limitation in grape must reduces yeast biomass and fermentation rate, resulting in incomplete fermentations with high levels of residual sugar, undesired by-products, and microbiological instability. Here, we used an optogenetic approach to demonstrate that expression of genes within region A is necessary to complete fermentations under low nitrogen availability. Overall, our results suggest that region A is a genetic signature for adaptation to low nitrogen conditions.

Physicochemical Profile of Canastra Cheese Inoculated with Starter Cultures of Kluyveromyces lactis and Torulaspora delbrueckii.

Canastra cheese, an artisanal cheese produced in Serra da Canastra-Brazil, has great cultural importance. Furthermore, this cheese has nutritional and sensory attributes that make it of great economic importance. Its microbiota is composed of different bacteria and yeasts. Some yeasts already isolated by our research group have been characterized as potential probiotics. Probiotic microorganisms have garnered scientific interest, as improvements in the physical, chemical and sensory characteristics of food products have been reported when these microorganisms are used. In this context, the objective of this work was to evaluate Kluyveromyces lactis and Torulaspora delbrueckii, which were previously isolated from Canastra cheese, as autochthonous starter cultures. Canastra cheese was produced under three different conditions: (1) cheese with "Pingo" (natural starter), (2) cheese with "Pingo" + yeast mixed culture, and (3) cheese with only mixed yeast culture. The results showed that the mixed yeast inoculum significantly influenced the lactic acid bacteria population. Yeast populations remained at around 106 CFU/g after 45 days of maturation. Furthermore, cheeses containing the yeast mixed with inoculum had an initial lactose content reduced by 92.80% compared to cheese produced with "Pingo" (87.70%). The antioxidant activity, evaluated using the ABTS method, showed that cheeses containing the mixed yeast culture had higher percentages of antioxidant activity at 45 days of maturation. The texture profile of the cheeses changed over time. In general, the cheese containing the yeast mixed culture and "Pingo" and the cheese containing "Pingo" had the lowest hardness at 30 days of maturation (5245 and 5404 N, respectively). Among the volatile compounds, 3-methylbutyl octanoate, phenethyl butyrate, phenethyl propionate, isobutyl butanoate and pentyl propionate were found only in cheeses produced with yeast mixed culture. The obtained results demonstrated that the use of autochthones probiotic cultures could improve the cheese characteristics without negatively impacting the traditional physicochemical attributes of Canasta cheese.

Screening and characterizing indigenous yeasts, lactic acid bacteria, and acetic acid bacteria from cocoa fermentation in Hainan for aroma Development.

Fermentation is crucial for inducing desirable flavor and aroma profiles in cocoa products. This research focused on identifying microbial strains isolated from spontaneous cocoa fermentation in Hainan through 16S and Internal Transcribed Spacer (ITS) sequencing. Pectinase activity was screened, and metabolic dynamics of sugars and organic acids were analyzed using high-performance liquid chromatography. Additionally, gas chromatography-mass spectrometry was employed for the quantification of volatile compounds. The fermentation potentials of isolated yeast, lactic acid bacteria, and acetic acid bacteria were analyzed from multiple perspectives. Pichia fermentans XY23.1 and Hanseniaspora uvarum XY23.1 exhibited significant pectinolytic activity, essential for breaking down pectin in cocoa pulp. Moreover, H. uvarum XY23.1, H. occidentalis XY23.1, Saccharomyces cerevisiae XY23.2, and P. fermentans XY23.1 were identified as producers of notable amounts of alcohols and esters, contributing sweet and floral notes to the fermentation profile. Furthermore, Levilactobacillus brevis exhibited strong fructophilicity, and Lactiplantibacillus plantarum strains showed high metabolic rates and lactic acid production abilities, crucial for enhancing fermentation efficiency. Assessment of growth rate and acid production performance revealed that Gluconobacter potus XY23.2 and Acetobacter oryzifermentans XY23.1 can produce less acid during rapid growth, avoiding flavor defects caused by excessive acidity. This study demonstrates the impact of various flavor compounds on the flavor characteristics of cocoa pulp. It highlights the potential of these microbial strains for use in starter culture cocktails, which can significantly improve the quality of cocoa products by enhancing desirable flavor and aroma profiles while maintaining balanced acidity. PRACTICAL APPLICATION: This study screened and characterized microorganisms isolated from the fermentation of Hainan cocoa (Trinitario) through a series of experiments, providing new insights for the future selection of cocoa fermentation starters.

Development of a Wine Yeast Strain Capable of Malolactic Fermentation and Reducing the Ethyl Carbamate Content in Wine.

In winemaking, malolactic fermentation (MLF), which converts L-malic acid to L-lactic acid, is often applied after the alcoholic fermentation stage to improve the sensory properties of the wine and its microbiological stability. MLF is usually performed by lactic acid bacteria, which, however, are sensitive to the conditions of alcoholic fermentation. Therefore, the development of wine yeast strains capable of both alcoholic fermentation and MLF is an important task. Using genome editing, we engineered a modified variant of the triploid wine yeast strain Saccharomyces cerevisiae I-328, in which the CAR1 arginase gene was replaced by the malate permease gene from Schizosaccharomyces pombe and the malolactic enzyme gene from Oenococcus oeni. Genome-wide transcriptional profiling confirmed the expression of the introduced genes and revealed a limited effect of the modification on global gene expression. Winemaking experiments show that genome editing did not affect fermentation activity and ethanol production, while use of the modified strain resulted in a tenfold reduction in malate content with simultaneous formation of lactate. The resulting wines had a softer and more harmonious taste compared to wine obtained using the parental strain. Inactivation of arginase, which forms urea and L-ornithine through the breakdown of arginine, also resulted in a twofold decrease in the content of urea and the carcinogenic ethyl carbamate in wine. Thus, the new strain with the replacement of the arginase gene with the MLF gene cassette is promising for use in winemaking.

Antioxidant activity and physico-chemical properties of mead suppemented with coffe

Mead is a fermented drink with honey as the main ingredient, being called melomel when fruits or grains are added. In this work, the objective was to evaluate the physical-chemical parameters and the antioxidant potential of mead produced with the addition of coffee. Meads were made in a process similar to wine making, involving the operations of preparing the pre-inoculum, the must, yeast inoculation, fermentation and packaging. The meads produced with and without the addition of coffee were subjected to physical-chemical analyzes (moisture, acidity, pH, alcoholic content, reducing sugars, soluble solids (ºBx), ash) and the antioxidant potential (phenolic compounds and total flavonoids, DPPH , ABTS and FRAP). It was observed that for the parameters of pH (3.41), ash (0.04%) and reducing sugar (107.71 g L-1) the mead with coffee obtained higher values compared to the control drink without the addition of the adjunct coffee, which in turn demonstrated higher performance in the moisture (88.26%) and acidity (65.7 mEq L-1, 4.9 g of tartaric acid L-1) analyses. When related to the alcohol content of the drinks, both showed the same significantly value of 11.62% (without coffee) and 13.53% (with coffee). Regarding the properties of phenolic compounds and total flavonoids, the mead with coffee presented higher levels (305.85 mg GA100 mL-1), flavonoids (33.47 mg Q 100 mL-1), DPPH (153.01 mg T 100 mL-1) and FRAP (1236.08 µmol Fe(II) 1000 mL-1). The traditional drink presented ABTS as the best antioxidant activity with 245.67 mg T 100 mL-1. Coffee additives significantly influenced the beverage's physicochemical and bioactive characteristics, promoting its antioxidant potential and functional performance.

Exploring Tamarind: A versatile spice and innovative value addition in wine production

Tamarind (Tamarindus indica L.) is a multipurpose ancient spice valued for its tangy-sweet flavor, which is being transformed through innovative post-harvest technologies into wine. The Fruit pulp is highly nutritious and various value-added products have been developed for easier handling, storage and transportation, while extending its shelf life. These products range from Tamarind toffee, Tamarind pickle, Tamarind jam, squash, wine and offering distinct flavors and potential health benefits. Table wine, fermented using tamarind pulp, is widely known for its medicinal properties and applications in the food industries. The must was extracted and fermented with sugar and two different strains of Saccharomyces cerevisiae (Red wine yeast and Belgian wit yeast), to produce wine from the pulp of red, sour and sweet varieties of tamarind. Bio-component and sensory analyses were conducted to identify the proximate and organoleptic attributes of the wine. The variation in proximate property values of wine were recorded as alcohol content (8.40% to 10.62%), moisture (23% to 29.5%), pH (2.38 to 3.45), ash (1.3% to 2.5%), total soluble solid (3.2 °Brix to 11 °Brix), titrable acidity (1 mg/ml to 5.1 mg/ml), carbohydrate (1.1% to 3.65%), vitamin C (10.3 mg/ml to 22.3 mg/ml), and antioxidant (37.1 mMol/l to 75.9 mMol/l). It was found that Belgian wit yeast yielded good production of wine from the sweet Tamarind. It showed optimal values for alcohol (8.14%), moisture (26%), pH (3.15), ash (2.1%), total soluble solid (9.3 °Brix), titrable acidity (2 mg/ml), carbohydrate (3.4%), vitamin C (22.3 mg/ml), antioxidant (74.6 mMol/l). It also registered the higher organoleptic values for flavor (7.3), color (7.0), aroma (6.5), consistency (7.5), taste (8.5) and overall acceptability (8.5). This research demonstrates a breakthrough in utilizing tamarind (Tamarindus indica) for producing value-added wine with optimal alcohol content (8%), high antioxidant activity (74.6 mMol/L) and excellent sensory attributes (8.5).

Биосинтез лактулозы с использованием ферментов лактозосбраживающих микромицет и бактерий

Lactulose is a well-studied prebiotic popular in medicine and the food industry. β-Galactosidases offer an alternative to traditional chemical methods of lactulose production. The article describes lactulose biosynthesis with crude enzyme preparations of β-galactosidases obtained by separate and joint cultivation of lactose-fermenting yeasts and lactic acid bacteria in whey permeate. The research featured the following producers of β-galactosidases: lactose-fermenting yeasts of Kluyveromyces lactis VKM Y-1333 and Y-1339, Kluyveromyces marxianus VKM Y-459 and Y-1338, and viscous strains of lactic acid bacteria of Lactobacillus acidophilus and Streptococcus thermophilis. The β-galactosidase activity was measured using the method of o-nitrophenyl-β-D-galactopyranoside hydrolysis. The method of high-performance liquid chromatography made it possible to reveal the carbohydrate composition. The lactulose formation by yeast enzymes demonstrated the following pattern: its concentration increased rapidly during the first 30 min of reaction with subsequent decrease or stabilization. Some combined unpurified enzyme preparations of yeasts and lactic acid microorganisms were more active than β-galactosidases obtained by separate cultivation. The patterns of lactulose formation depended on both the yeast strain and the type of lactic acid bacteria. The highest yields of lactulose belonged to the samples that combined β-galactosidases of all yeast strains with Streptococcus thermophilis. Co-cultivation of yeast and lactic acid bacteria in some combinations produced combined crude enzyme preparations with higher activity and greater lactulose yields than separate yeast cultivation. These results can help to obtain purified enzyme preparations of β-galactosidases and lactulose-containing products from secondary dairy raw materials.

Effects of Oregano Essential Oil and/or Yeast Cultures on the Rumen Microbiota of Crossbred Simmental Calves.

This study hypothesized that combining oregano essential oil (OEO) and yeast cultures (YCs) would modulate rumen microbiota to promote gastrointestinal homeostasis and function. Twenty-four newborn, healthy, disease-free, crossbred Simmental male calves (birth weight ≥ 35 kg) were assigned to one of four treatments based on birth data. Treatments were as follows: (1) Control (CON), calves fed calf starter without additives; (2) OEO, calves fed calf starter containing 60 mg/kg body weight (BW) of OEO per day; (3) YCs, calves fed calf starter containing 45 mg/kg BW of YC per day; and (4) MIX, calves fed calf starter with OEO (60 mg/kg, BW) and YC (45 mg/kg, BW) combination. The experimental period lasted 70 days. Rumen fluid was collected on the final day, and 16S rRNA sequencing was performed to assess alterations in rumen microbiota. Calves fed MIX exhibited significantly greater microbial richness, species diversity, and lineage diversity (p < 0.05) compared with calves in the other groups. MIX-fed calves also showed changes (p < 0.05) in the relative abundance of certain rumen species, identified as through LEfSe analysis (LDA > 4, p < 0.05). These biomarkers included f_Rikenellaceae, g_Rikenellaceae_RC9_gut_group, g_Erysipelotrichaceae_UCG-002, c_Saccharimonadia, o_Saccharimonadales, f_Saccharimonadaceae, and g_Candidatus_Saccharimonas. Pathways enriched (p < 0.05) in MIX-fed calves involved nucleotide metabolism, lipid metabolism, glycan biosynthesis and metabolism, amino acid metabolism, terpenoids and polyketides metabolism, antimicrobial drug resistance, xenobiotic biodegradation and metabolism, antineoplastic drug resistance, and excretory system pathways. In conclusion, this study demonstrates that the OEO and YC combination enhances rumen microbial community modulation in calves more effectively than OEO or YCs fed individually or with the control diet.

Spatio-temporal distribution and biotechnological potential of culturable yeasts in the intertidal sediments and seawater of Aoshan Bay, China.

Marine yeasts play a crucial role in marine microbial ecology, facilitating the biogeochemical cycling of carbon and nitrogen in marine ecosystems, while also serving as important reservoirs of bioactive compounds with extensive applications in pharmaceuticals, agriculture, and various industries. Intertidal flats, characterized by their complex ecological dynamics, are postulated to harbor a wealth of yeast resources. This study employed a culture-dependent approach to assess the diversity, spatio-temporal distribution, and biotechnological potential of yeast communities residing within the intertidal sediments and seawater of Aoshan Bay. A total of 392 yeast strains were identified from 20 distinct genera, encompassing 43 recognized species and four candidate novel species. Notably, 17 of these species were identified as novel occurrences in marine environments, underscoring the rich yeast biodiversity of the Aoshan Bay ecosystem, with Candida emerging as the dominant genus in both sedimentary and aqueous habitats. Yeast community composition exhibited significant spatial and temporal variation, with peak diversity and abundance observed in autumn, the subtidal zone, and the surface soil layer. No clear pattern, however, emerged linking these shifts to specific changes in community composition, highlighting the complex interactions between microbial communities, environmental variables, and anthropogenic disturbance. Although several yeast species isolated here have been previously recognized for their biotechnological potential, their diverse and abundant extracellular enzyme profiles were characterized, further highlighting their crucial role in organic matter decomposition and nutrient cycling within the tidal ecosystem, as well as their potential applicability in the food, fine chemical, textile, and pharmaceutical industries.IMPORTANCEThis study presents groundbreaking insights into the yeast diversity of Aoshan Bay, offering invaluable information on their spatial and temporal distribution patterns, as well as their biotechnological potential in the tidal environment. The findings reveal that the eutrophic intertidal flat is a rich repository of yeasts with abundant extracellular enzymatic activity and an important role in nutrient cycling and decomposition processes. Also, these yeasts serve as crucial indicators of ecosystem health and function and are excellent candidates for biotechnological and industrial applications. Collectively, this study not only expands our knowledge of the diversity and distribution of intertidal yeasts but also highlights their promising potential for biotechnological applications.

Effects of Ultrasound Application on the Improvement of Probiotic Properties and Antioxidant Activity of Kluyveromyces marxianus, Saccharomyces cerevisiae var. boulardii and Saccharomyces cerevisiae

The objective of this study was to ascertain the impact of ultrasound application on the probiotic characteristics and antioxidant activity of yeasts. In this context, the pH changes, probiotic properties and antioxidant activities of K. marxianus (Km), S. boulardii (Sb) and S. cerevisiae (Sc) were determined by ultrasound application at different durations (5, 15, 30 and 60 minutes at 24 kHz). The lowest pH values were determined for cultures of Km (ultrasound non-applied K. marxianus), Sb-30 (30 min. ultrasound applied S. boulardii) and Sc-5 (5 min. ultrasound applied S. cerevisiae) as 4.48, 5.15 and 5.26, respectively. The hydrophobicity values of the yeast strains varied between 6% and 24%, increased with ultrasound application. Although S. boulardii had the highest tolerance to low pH and bile salts, the resistance of all yeast to low pH and bile salts decreased with ultrasound application. K. marxianus had the least survival under in vitro conditions, but ultrasound application increased survival of K. marxianus strains and slightly affected the survival rate of S. boulardii and S. cerevisiae. Increasing of duration time of ultrasound application resulted higher antioxidant activity and so the highest antioxidant activity was determined for Sb-60. Finally, ultrasound application could be used for the development of hydrophobicity and antioxidant properties of yeast cultures.

Wine Yeast Strains Under Ethanol-Induced Stress: Morphological and Physiological Responses

During alcoholic fermentation, ethanol accumulation significantly impacts yeast cells by disrupting membrane integrity, increasing permeability, and reducing cell viability. This study evaluated the effects of ethanol stress on the growth, membrane fluidity, and cell surface morphology of Saccharomyces cerevisiae and non-Saccharomyces yeast strains, specifically Torulaspora delbrueckii and Metschnikowia pulcherrima. These strains, commercialized by AEB SpA and preserved at the Unimore Microbial Culture Collection (UMCC), were tested for fermentative performance in grape must and grown under varying ethanol concentrations. Membrane fluidity was measured using Laurdan generalized polarization (GP), while Atomic Force Microscopy (AFM) assessed cell surface morphology. Results indicated that at 10% ethanol, membrane fluidity increased, particularly in strains able to tolerate up to 16% ethanol, which also demonstrated superior fermentative performance. Less tolerant strains, such as T. delbrueckii UMCC 5 and M. pulcherrima UMCC 15, showed smaller increases in fluidity. At 18% ethanol, these strains exhibited severely altered surface morphology and larger surface roughness values, suggesting increased instability under high ethanol stress, while more tolerant strains displayed better-preserved surface morphology and lower roughness values, reflecting enhanced adaptability. These findings offer insights into yeast responses to ethanol stress, supporting the development of more resilient strains for improved fermentation.

Clinical characteristics and outcomes of colonization and infection by yeast species in solid organ transplant recipients: Molecular identification and antifungal susceptibility patterns of isolates.

Fungal infections are serious complications after solid organ transplantation, with high mortality and morbidity. Given the importance of the local epidemiological data and also extensive prophylactic regimens in solid organ transplant (SOT) recipients, this study aimed to investigate the clinical characteristics and resistance patterns of yeast isolates in SOT recipients at a main referral transplant center in Iran. Of the 275 recipients enrolled, 22 (8%) had at least one positive yeast culture at a median of 5 days after transplantation. Bacterial infection and reoperation were significantly associated with colonization or infection caused by yeast species (P = .001). Moreover, mortality and length of ICU/hospital stay were significantly higher in patients with positive yeast cultures (P<.05). The most frequent species isolated was Candida albicans (50%), followed by C. glabrata (22.7%). Of species with definite breakpoints, the fluconazole-resistant rate was 23%. Caspofungin and amphotericin B showed potent activity against all isolates. Regarding the high risk of fungal infections, awareness of local epidemiological trends and resistance patterns can help improve outcomes in SOT recipients.

Gellan-amino acid hydrogel-based bioreactor for optimizing the production of yeast metabolites

Hydrogels mimic natural environments due to their hydrated, polymeric networks which are beneficial for microorganism growth. The substantial water content maintains a consistently moist environment, and porous structure of hydrogel promotes efficient nutrient transfer and cell distribution, offering advantages over traditional liquid bioreactors. While their application in cell immobilization for bioconversion is well-known, their use as a solid-state fermentation matrix remains unexplored. This study is the first attempt to integrate gellan and amino acids to develop an innovative hydrogel bioreactor. The performance of this system was determined by cultivating Rhodosporidium sp. (MTCC 9733) as a model organism and evaluating its metabolite production. Further, gellan and amino acids concentration was optimized using one-factor-at-a-time and D-optimal response surface methodologies to produce β-carotene, lipid, and protein. Additionally, a comparison of productivity, yield, and process economics suggested that novel solid-state hydrogel fermentation approach outperformed classical submerged fermentation in YMB liquid media. Moreover, rheological properties of optimized hydrogel, conducted before and after yeast cultivation, revealed that this system possesses significant mechanical strength and structural integrity. Such attributes render the hydrogel suitable for utilization across multiple fermentation cycles. Hence, this study illustrates the potential of gellan-amino acid hydrogels as sustainable, efficient alternatives to conventional fermentation methods.

A Comprehensive Review on Fouling of Heat Transfer Units in Sugar Factory Ethanol Plant: Mechanisms and Mitigation Methods

ABSTRACTFouling in heat transfer units has a negative economic impact. Many scale‐forming impurities are present in cane molasses generated by sugar cane production technology, including cations of aluminum (Al), calcium (Ca), iron (Fe), magnesium (Mg), potassium (K), sodium (Na), as well as anions of carbonates, sulfites, phosphates, sulfate, silicates, and chlorides. Ca cations, in particular, form insoluble complexes with many other chemical constituents, making them a scale‐forming impurity. The accumulation of Ca ion on the heat exchanger's surface could increase heat transfer resistance and reduce its overall efficiency. This article reviews many types of heat‐transmitting unit fouling and their successive fouling occurrences. Identifying the chemicals found in scale deposits helps to determine which cleaning products will effectively clean heat transfer units and which scale inhibitors will drastically lower scale formation rates. Furthermore, numerous unit operations and unit processes, such as molasses pre‐treatment and pre‐fermentation practice (inoculation of yeast), followed by fermentation practice, and product purification practice distillation, are used to limit deposit formation and boost ethanol production efficiency. Molasses pre‐treatment and treatment such as chemical treatment, heat treatment, acid centrifugation, and mechanical treatment are critical in decreasing scale development during heat exchange operations.

Metagenomic analysis and bioactive profiling of kombucha fermentation: antioxidant, antibacterial activities, and molecular docking insights into gastric cancer therapeutics.

Kombucha is fermented and produced with a biofilm called a symbiotic culture of bacteria and yeast, which is drunk all over the world for its beneficial effects on human health and energy levels. The metagenomic study of kombucha frequently detected microorganisms in proteobacteria, firmicutes, and actinobacteria. And also, yeast and fungi are Ascomycota and Basidiomycota is present in green leaf and sugarcane juice fermented kombucha. The kombucha extracts' biological activities were assessed using pH, total phenolic content, antioxidant, antibacterial, and anticancer activity. Fermentation may enhance biological activity and the generation of bioactive substances. These results showed the pH-3.1±0.2 and TPC -0.721μg/mL of gallic acid equivalent. The antioxidant radicals scavenging activity of kombucha was evaluated by DPPH, ABTS, H2O2 and TAC. The bioactive chemicals identified by FT-IR and HR-LC/MS analysis of Kombucha totaled 45 components. The identified compounds were further move on to perform molecular docking study against gastric cancer target proteins 4H9M, 2DQ7 and 1TVO are binding with Nequinate compounds showing best LibDock scores 105.12, 114.49, and 108.97. So, this study suggests that knowledge can potentially active bioactive compounds are present in kombucha and it's stimulated the mechanism of gastrointestinal transit. Additionally, the metagenomic analysis gives strength to understand the bacterial and fungal distribution and its molecular mechanism from Kombucha.

Untargeted LC-HRMS analyses reveal metabolomic specificities between wine yeast strains selected for their malic acid production.

The alcoholic fermentation of wine is mostly achieved by the species Saccharomyces cerevisiae that display a large variability for their ability to consume or produce malic acid. To better characterize the metabolism of such group of strains we explored their non-volatile metabolome using an untargeted LC-HRMS approach. The chemical classes and the putative structures of several hundred compounds where annotated using MS2 spectra using the SIRIUS software. By using both supervised and univariate statistical analyses, several metabolic features able to discriminate the two group of strains in several wines were listed. Quantitative enrichment analyses pointed out drastic differences in pantothenic acid metabolism between the two group of strains. In addition, the produced showed important change in their nitrogen composition that might be due to the pH difference in the resulting wines. Altogether this work paves the avenue for better characterizing the biochemical impact of yeast strains that modulate wine acidity.