Yeast Culture Research Articles

Studying the efficiency of Gaprin application in sterlet farming

In the course of the experiment, the influence of new feed additives created on the basis of Gaprin and representing biomass of inactivated cell culture of non-pathogenic methane-oxidizing yeasts or bacteria on sturgeon fish productivity indicators was studied. The research was carried out in the Krasnodar Territory on sterlet fingerlings. The experiment lasted for 60 days. According to the scheme of the experiment, the 1st (control) group of fish received complete feeds without additives, i.e. containing 100.0% fish meal. In group 2 feeding, 50.0% fishmeal was replaced with 50.0% Gaprin. Group 3 diet contained 25.0% fishmeal and 75.0% Gaprin. In the feed for group 4, fish meal and Gaprin were in the ratio of 75/25%. In Group 5, fish meal was completely replaced by Gaprin, in this case the amount of additive was 10.5 kg. Sterlet fingerlings from Group 6 received feed with 10.0% Gaprin. The initial live weight in all groups was similar at 30 g. However, the inclusion of Gaprin in the diet by reducing the amount of fish meal contributed to an increase in the final live weight of sterlets in the experimental groups by 4.4–19.4% compared to the control. The exceptions were groups 5 and 6, which received 100.0 and 90.0% Gaprin instead of fishmeal. Final live weight in these groups was lower by 2.3 and 0.9%, respectively. Feed costs per 1 kg of live weight gain in the groups with partial or complete replacement of fish meal were lower relative to the 1st group (from 7.0 to 17.9%,).Inclusion of Gaprin in complete feeds contributed to the increase in profit from 553.00 to 1785.00 rubles.

Comparison of Anti-Inflammatory and Antibacterial Properties of Raphanus sativus L. Leaf and Root Kombucha-Fermented Extracts.

In the cosmetics industry, the extract from Raphanus sativus L. is fermented using specific starter cultures. These cosmetic ingredients act as preservatives and skin conditioners. Kombucha is traditionally made by fermenting sweetened tea using symbiotic cultures of bacteria and yeast and is used in cosmetic products. The aim of this study was to evaluate the cosmetic properties of radish leaf and root extract fermented with the SCOBY. Both unfermented water extracts and extracts after 7, 14, and 21 days of fermentation were evaluated. The analysis of secondary plant metabolites by UPLC-MS showed higher values for ferments than for extracts. A similar relationship was noted when examining the antioxidant properties using DPPH and ABTS radicals and the protective effect against H2O2-induced oxidative stress in fibroblasts and keratinocytes using the fluorogenic dye H2DCFDA. The results also showed no cytotoxicity to skin cells using Alamar Blue and Neutral Red tests. The ability of the samples to inhibit IL-1β and COX-2 activity in LPS-treated fibroblasts was also demonstrated using ELISA assays. The influence of extracts and ferments on bacterial strains involved in inflammatory processes of skin diseases was also assessed. Additionally, application tests were carried out, which showed a positive effect of extracts and ferments on TEWL and skin hydration using a TEWAmeter and corneometer probe. The results obtained depended on the concentration used and the fermentation time.

Improvement of the recombinant phytase expression by intermittent feeding of glucose during the induction phase of methylotrophic yeast Pichia pastoris.

For growth of methylotrophic yeast, glycerol is usually used as a carbon source. Glucose is used in some cases, but not widely consumed due to strong repressive effect on AOX1 promoter. However, glucose is still considered as a carbon source of choice since it has low production cost and guarantees growth rate comparable to glycerol. In flask cultivation of the recombinant yeast, Pichia pastoris GS115(pPIC9K-appA38M), while methanol induction point(OD600) and methanol concentration significantly affected the phytase expression, glucose addition in induction phase could enhance phytase expression. The optimal flask cultivation conditions illustrated by Response Surface Methodology were 10.37 OD600 induction point, 2.02h before methanol feeding, 1.16% methanol concentration and 40.36μL glucose feeding amount(for 20mL culture volume) in which the expressed phytase activity was 613.4 ± 10.2U/mL, the highest activity in flask cultivation. In bioreactor fermentation, the intermittent glucose feeding showed several advantageous results such as 68h longer activity increment, 149.2% higher cell density and 200.1% higher activity compared to the sole methanol feeding method. These results implied that remaining glucose at induction point might exhibit a positive effect on the phytase expression. Glucose intermittent feeding could be exploited for economic phytase production and the other recombinant protein expression by P. pastoris GS115.

Gradient boosted regression as a tool to reveal key drivers of temporal dynamics in a synthetic yeast community.

Microbial communities are vital to our lives, yet their ecological functioning and dynamics remain poorly understood. This understanding is crucial for assessing threats to these systems and leveraging their biotechnological applications. Given that temporal dynamics are linked to community functioning, this study investigated the drivers of community succession in the wine yeast community. We experimentally generated population dynamics data and used it to create an interpretable model with a gradient-boosted regression tree approach. The model was trained on temporal data of viable species populations in various combinations, including pairs, triplets, and quadruplets, and was evaluated for predictive accuracy and input feature importance. Key findings revealed that the inoculation dosage of non-Saccharomyces species significantly influences their performance in mixed cultures, while Saccharomyces cerevisiae consistently dominates regardless of initial abundance. Additionally, we observed multispecies interactions where the dynamics of Wickerhamomyces anomalus were influenced by Torulaspora delbrueckii in pairwise cultures, but this interaction was altered by the inclusion of S. cerevisiae. This study provides insights into yeast community succession and offers valuable machine learning-based analysis techniques applicable to other microbial communities, opening new avenues for harnessing microbial communities.

Impact of different fermentation times on the microbiological, chemical, and sensorial profile of coffees processed by self-induced anaerobiosis fermentation.

Variation in fermentation time may be an essential alternative to provide coffee beverages with different and unique sensory profiles. This work investigated the microbiological, chemical, and sensory changes in coffees submitted to different fermentation durations (0, 24, 48, 72, and 96h). Self-induced anaerobiosis fermentation (SIAF) was used, and two treatments were performed: spontaneous fermentation and inoculation with S. cerevisiae CCMA0543. Microbiological analyses were performed, and the permanence of the inoculum was monitored. Chromatography (sugars, organic acids, and volatile compounds) was analyzed, and sensory analysis (temporal dominance of sensations - TDS) was performed. A total of 228 isolates were identified during spontaneous fermentation. The dominant bacteria and yeasts were Leuconostoc mesenteroides, Lactiplantibacillus plantarum, Staphylococcus warneri, Bacillus sp., Torulaspora delbrueckii, Hanseniaspora uvarum, and Meyerozyma caribbica. High concentrations of citric (18.67 mg.g- 1) and succinic (5.04 mg.g- 1) acids were detected at 96h in SIAF fermentation. One hundred twenty-one volatile compounds were detected, but 22 were detected only in inoculated coffees. In spontaneous fermentation, 48h of fermentation showed woody notes, while 72h showed chestnuts. However, in the inoculated coffee, 72h of fermentation showed high fruity dominance, and 96h of fermentation was the only one with herbaceous notes. In addition, yeast inoculation increased the intensity of caramel notes in the first 48h and increased the fruity flavor after 72h of fermentation. Therefore, the type of fermentation (with or without inoculation) and the chosen fermentation time will depend on the sensorial profile the producer intends to obtain.

Dietary 5-hydroxytryptophan improves sheep growth performance by enhancing ruminal functions, antioxidant capacity, and tryptophan metabolism: in vitro and in vivo studies.

Hydroxytryptophan (5-HTP) can regulate the synthesis of 5-Hydroxytryptamine (5-HT) and melatonin (MT). In a previous metabolome analysis, we found that 5-HTP is an effective ingredient in yeast culture for regulating rumen fermentation. However, research on the effect of this microbial product (5-HTP) as a functional feed additive in sheep production is still not well explained. Therefore, this study examined the effects of 5-HTP on sheep rumen function and growth performance using in vitro and in vivo models. A two-factor in vitro experiment involving different 5-HTP doses and fermentation times was conducted. Then, in the in vivo experiment, 10 sheep were divided into a control group which was fed a basal diet, and a 5-HTP group supplemented with 8 mg/kg 5-HTP for 60 days. The results showed that 5-HTP supplementation had a significant effect on in vitro DMD, pH, NH3-N, acetic acid, propionic acid, and TVFA concentrations. 5-HTP altered rumen bacteria composition and diversity indices including Chao1, Shannon, and Simpson. Moreover, the in vivo study on sheep confirmed that supplementing with 8 mg/kg of 5-HTP improved rumen fermentation efficiency and microbial composition. This led to enhanced sheep growth performance and increased involvement in the tryptophan metabolic pathway, suggesting potential benefits. Dietary 5-HTP (8 mg/kg DM) improves sheep growth performance by enhancing ruminal functions, antioxidant capacity, and tryptophan metabolism. This study can provide a foundation for the development of 5-HTP as a functional feed additive in ruminants' production.

Utilization of Free and Dipeptide-Bound Formyline and Pyrraline by Saccharomyces Yeasts.

The utilization of the glycated amino acids formyline and pyrraline as well as their peptide-bound derivatives by 14 Saccharomyces yeasts, including 6 beer yeasts (bottom and top fermenting), one wine yeast, 6 strains isolated from natural habitats and one laboratory reference yeast strain (wild type) was investigated. All yeasts were able to metabolize glycated amino acids via the Ehrlich pathway to the corresponding Ehrlich metabolites. While formyline and small amounts of pyrraline entered the yeast cells via passive diffusion, the amounts of dipeptide-bound MRPs, especially the dipeptides glycated at the C-terminus, decreased much faster, indicating an uptake into the yeast cells. Furthermore, the glycation-mediated hydrophobization in general leads to an faster degradation rate compared to the native lysine dipeptides. While the utilization of free formyline is yeast-specific, the amounts of (glycated) dipeptides decreased faster in the presence of brewer's yeasts, which also showed a higher formation rate of Ehrlich metabolites compared to naturally isolated strains. Due to rapid uptake of alanyl dipeptides, it can be assumed that the Ehrlich enzyme system of naturally isolated yeasts is overloaded and the intracellularly released MRP is primarily excreted from the cell. This indicates adaptation of technologically used yeasts to (glycated) dipeptides as a nitrogen source.

Development of a defined mixed starter culture for the improvement of Tej, Ethiopian honey wine.

Ethiopian honey wine, Tej, is the most popular traditionally fermented alcoholic beverage in Ethiopia. Owing to the spontaneous fermentation process, the final product is neither predictable nor consistent in quality. Attempts have not been made before to solve this problem. Thus, the aim of this study was to develop a potential mixed starter culture of yeast and lactic acid bacteria isolated from Tej samples for the production of Tej with consistent quality. One hundred seventy-seven lactic acid bacteria and 194 yeasts were isolated from 30 Tej samples collected from southwest Ethiopia. After sequentially testing the isolates towards physiological stress tolerance and desired metabolic products, 10 lactic acid bacteria and 10 yeast isolates were screened. Later, four lactic acid bacteria and four yeast isolates were found to be compatible in co-culture tests. Finally, the combination of lactic acid bacteria and yeast isolates was formulated using the design of expert version 7.0.0 software, and six formulates (F #1-6) were designed. Controlled Tej fermentation was performed under laboratory conditions using six lactic acid bacteria-yeast starter culture formulations. The sensory attributes, in terms of color, flavor, odor, turbidity, and overall acceptance analysis scored 4.8/5.0 (F #2) and 4.7/5.0 (F #6), with mean significant variations (p < 0.05) among the other formulates. These two formulates were considered the best-mixed starter cultures compared to the control and other formulates. Matrix-assisted laser desorption ionization-time of flight analysis revealed that the lactic acid bacteria starters (AAUL7 and AAUL10) belonged to Lactobacillus paracasei. While the yeast starters (AAUY2 and AAUY8) belonged to Saccharomyces cerevisiae. These mixed lactic acid bacteria-yeast starter cultures could be used as the best starter culture for the fermentation of Ethiopian honey wine, Tej, with consistent quality.

Investigating the concomitant production of carotenoids and lipids by the yeast Rhodosporidium babjevae using sugarcane bagasse hydrolysate or corn steep liquor

The yeast Rhodosporidium babjevae was used to produce carotenoids, lipids, and fatty acids using sugarcane bagasse hydrolysates or glucose. Investigating the impact of glucose concentrations (10–150 g/L), the yeast showed the capability to yield 16.9 g/L biomass and 10.5 g/L lipids at 60 g glucose/L, while the highest pigments concentration (312 μg/g) was observed at 10 g glucose/L. Pre-treatment methods, including organosolv (ethanol 60 %(w/w)), alkali (NaOH 2 %(w/v)) and alkaline-organosolv (ethanol 60 %(w/w) and NaOH 2 %(w/v)) were used on the sugarcane bagasse following enzymatic hydrolysis. Among these, alkaline organosolv pre-treatment exhibited the most effective lignin removal of 81.9 %, releasing 46.7 g/L sugars by hydrolysis. Yeast cultivation on the enzymatic hydrolysates of alkaline organosolv pre-treatment resulted in the highest biomass (9.6 g/L) and lipids (5.0 g/L) yields. However, the highest content of pigments (280 μg/g) was achieved when the yeast was cultivated on the enzymatic hydrolysates of organosolv pre-treatment. Production of 11.3 g/L biomass, 204 μg/g pigments, and 6.7 g/L lipids established that corn steep liquor holds potential as a cheap and viable alternative to yeast extract as nitrogen source. The analysis of fatty acid composition revealed the prevalence of oleic acid and linoleic acid as dominant components.

Correction: Pinu et al. The Effect of Yeast Inoculation Methods on the Metabolite Composition of Sauvignon Blanc Wines. Fermentation 2023, 9, 759

There was a technical error in the calculation of yeast cell concentrations from cell numbers in the original publication [...]

Agricultural Waste Management by Production of Second-Generation Bioethanol from Sugarcane Bagasse Using Indigenous Yeast Strain.

In the wake of rapid industrialization and burgeoning transportation networks, the escalating demand for fossil fuels has accelerated the depletion of finite energy reservoirs, necessitating urgent exploration of sustainable alternatives. To address this, current research is focusing on renewable fuels like second-generation bioethanol from agricultural waste such as sugarcane bagasse. This approach not only circumvents the contentious issue of food-fuel conflicts associated with biofuels but also tackles agricultural waste management. In the present study indigenous yeast strain, Clavispora lusitaniae QG1 (MN592676), was isolated from rotten grapes to ferment xylose sugars present in the hemicellulose content of sugarcane bagasse. To liberate the xylose sugars, dilute acid pretreatment was performed. The highest reducing sugars yield was 1.2% obtained at a temperature of 121°C for 15min, a solid-to-liquid ratio of 1:25 (% w/v), and an acid concentration of 1% dilute acid H2SO4 that was significantly higher (P < 0.001) yield obtained under similar conditions at 100°C for 1h. The isolated strain was statistically optimized for fermentation process by Plackett-Burman design to achieve the highest ethanol yield. Liberated xylose sugars were completely utilized by Clavispora lusitaniae QG1 (MN592676) and gave 100% ethanol yield. This study optimizes both fermentation process and pretreatment of sugarcane bagasse to maximize bioethanol yield and demonstrates the ability of isolated strain to effectively utilize xylose as a carbon source. The desirable characteristics depicted by strain Clavispora lusitaniae shows its promising utilization in management of industrial waste like sugarcane bagasse by its conversion into renewable biofuels like bioethanol.

3D printed kombucha biomaterial as a tissue scaffold and L929 cell cytotoxicity assay

AbstractTissue engineering includes the construction of tissue‐organ scaffold. The advantage of three‐dimensional scaffolds over two‐dimensional scaffolds is that they provide homeostasis for a longer time. The microbial community in Symbiotic culture of bacteria and yeast (SCOBY) can be a source for kombucha (kombu tea) production. In this study, it was aimed to investigate the usage of SCOBY, which produces bacterial cellulose, as a biomaterial and 3D scaffold material. 3D printable biomaterial was obtained by partial hydrolysis of oolong tea and black tea kombucha biofilms. In order to investigate the usage of 3D kombucha biomaterial as a tissue scaffold, “L929 cell line 3D cell culture” was created and cell viability was tested in the biomaterial. At the end of the 21st day, black tea showed 51% and oolong tea 73% viability. The cytotoxicity of the materials prepared by lyophilizing oolong and black tea kombucha beverages in fibroblast cell culture was determined. Black tea IC50 value: 7.53 mg, oolong tea IC50 value is found as 6.05 mg. Fibroblast viability in 3D biomaterial + lyophilized oolong and black tea kombucha beverages, which were created using the amounts determined to these values, were investigated by cell culture Fibroblasts in lyophilized and 3D biomaterial showed viability of 58% in black tea and 78% in oolong tea at the end of the 7th day. In SEM analysis, it was concluded that fibroblast cells created adhesion to the biomaterial. 3D biomaterial from kombucha mushroom culture can be used as tissue scaffold and biomaterial.

Date Vinegar: First Isolation of Acetobacter and Formulation of a Starter Culture.

There is a lack of scientific analysis and control over the production of date vinegar in Oman, despite its growing demand in the worldwide market. Traditional production of date vinegar may lead to elevated amounts of ethanol (≥0.5%) and reduced content of acetic acid (<4%) compared to the standard acceptable levels. This study aimed to isolate non-Gluconobacter species from date vinegar produced by spontaneous fermentation and formulate starter cultures for quick and efficient production of date vinegar. In spontaneous fermentation date vinegar samples, the highest concentration of acetic acid was 10.42% on day 50. Acetobacter malorum (5 isolates), A. persici (3 isolates), and A. tropicalis (3 isolates) were identified based on 16S rRNA gene sequences for the first time in date vinegar. For date vinegar prepared with a starter culture of Acetobacter and yeast, the highest concentration of acetic acid was 4.67%. In conclusion, spontaneous fermentation resulted in the production of date vinegar with a high concentration of acetic acid, acceptable concentrations of ethanol and methanol, and the first isolation of three Acetobacter species. The formulated starter culture produced acceptable amounts of acetic acid and the time of fermentation was reduced 10 times (from 40 days to 4 days). This can provide the basis for producing a personalized or commercial product that ensures the production of good-quality date vinegar in an easier, faster, safer, and more efficient way from low-quality and surplus dates.

The Value of Indigenous &lt;i&gt;Saccharomyces cerevisiae&lt;/i&gt; Strains as Useful Enzymes Producers: A Systematic Review

This systematic review has focused on the selection and characterization of indigenous Saccharomyces cerevisiae strains for enzymes' production obtained from the fermentation process. The primary studies assessed have demonstrated that indigenous S. cerevisiae strains produce a wide range of enzymes during fermentation. These strains have shown different characteristics and were isolated from various locations, including those belonging to the main components of the wine production chain. The research methodology applied to find primary studies about the optimal conditions for enzyme production was effective and identified a wide range of enzyme classes. Cultivation media amended with natural or synthetic inducer substrates were found to be suitable carbon and/or nitrogen sources for producing enzymes of interest in plate-based screening. In submerged fermentation studies, the use of agro-industrial residues has been identified as a relevant carbon source for microbe development and metabolism. For the indigenous S. cerevisiae strains, the majority of the enzymes found belong to the glucosidases and hydrolases classes. Due to the activity of these enzymes, yeasts have been traditionally used in classic biotechnological applications, particularly in the process of alcoholic fermentations. Those enzymes are responsible for producing metabolites (such as aromatic compounds) that contribute to the desirable aroma and/or taste during the fermentation of wine, as well as other fermented or distilled beverages. The methods used for enzyme screening were of quantitative and/or qualitative nature and were carried out under acidic pH conditions (3.5-6.5) and at temperatures of 28-35 ℃. The results of this systematic review have shown that the enzymes from indigenous S. cerevisiae are highly relevant in various biotechnological applications, particularly in the food industry. Conclusions and future perspectives of our findings were discussed in terms of potential developments of novel application methods of the indigenous yeasts and their enzymes in agriculture and industry.

Uniform experimental design optimization of liquid fermentation Baijiu mixed fermentation

In this study, corn alcohol fermentation mash was used as raw material, and different microorganisms were added to improve the flavor of liquid fermentation Baijiu. The optimum fermentation conditions of liquid fermentation Baijiu were optimized by uniform experimental design. The optimum fermentation conditions were as follows: Saccharomyces cerevisiae: non-Saccharomyces cerevisiae=3.8:1, yeast inoculation amount was 0.65 g/g, Lactobacillus inoculation amount was 1%, yeast inoculation time was 26.5 h, Lactobacillus inoculation time was 0.5 h, the total acid content was 1.943 g/L, the estimated total acid yield was 2.036 g/L, and the relative deviation was 0.077%. Compared with the three control groups, the total acid yield increased by 27.39%, 12.36% and 19.05% respectively.

Tannin-Tolerant Saccharomyces cerevisiae Isolated from Traditional Fermented Tea Leaf (Miang) and Application in Fruit Wine Fermentation Using Longan Juice Mixed with Seed Extract as Substrate.

This study focused on isolating tannin-tolerant yeasts from Miang, a fermented tea leaf product collected from northern Laos PDR, and investigating related food applications. From 43 Miang samples, six yeast isolates capable of ethanol production were obtained, with five isolates showing growth on YPD agar containing 4% (w/v) tannic acid. Molecular identification revealed three isolates as Saccharomyces cerevisiae (B5-1, B5-2, and C6-3), along with Candida tropicalis and Kazachstania humilis. Due to safety considerations, only Saccharomyces spp. were selected for further tannic acid tolerance study to advance food applications. Tannic acid at 1% (w/v) significantly influenced ethanol fermentation in all S. cerevisiae isolates. Notably, B5-2 and C6-3 showed high ethanol fermentation efficiency (2.5% w/v), while others were strongly inhibited. The application of tannin-tolerant yeasts in longan fruit wine (LFW) fermentation with longan seed extract (LSE) supplementation as a source of tannin revealed that C6-3 had the best efficacy for LFW fermentation. C6-3 showed promising efficacy, particularly with LSE supplementation, enhancing phenolic compounds, antioxidant activity, and inhibiting α-glucosidase activity, indicating potential antidiabetic properties. These findings underscore the potential of tannin-tolerant S. cerevisiae C6-3 for fermenting beverages from tannin-rich substrates like LSE, with implications for functional foods and nutraceuticals promoting health benefits.

Impact of Selected Yeast Strains on Quality Parameters of Obtained Sauerkraut

The aim of this research was to determine the influence of yeast strains (previously isolated from the fermentation process) on selected quality parameters of sauerkraut. For this purpose, shredded and salted (2.5% w/w) cabbage of the Galaxy variety was fermented in the absence of oxygen with the addition of 2 × 106 cells of a selected yeast culture. The control sample was spontaneously fermented sauerkraut without yeast addition. The obtained sauerkraut was analysed in terms of the content of selected organic acids, sugars and polyols (HPLC), selected volatile compounds (HS-SPME-GC-TOFMS), colour (CieLAB) and aroma (QDA). Yeast P. fermentans, Rh. mucilaginosa and W. anomalus reduced crucial sauerkraut components such as lactic acid, glycerol, and certain volatile compounds, leading to decreased aroma intensity and acceptability. Additionally, an increase in glucosinolate decomposition products was observed. Conversely, D. hansenii positively influenced sauerkraut quality by enhancing lactic acid content and exhibiting similar volatile characteristics to those of the control. Two of the three samples fermented with D. hansenii received high sensory analysis scores akin to those of the control. Sauerkraut fermented with Cl. lusitaniae yeast contained elevated levels of volatile compounds—alcohols, esters and lactones—resulting in an intense floral aroma, albeit receiving lower overall ratings due to deviation from the typical profile.

Characterization of bacterial cellulose produced by the KomEt strain isolated from a kombucha SCOBY

Bacterial cellulose (BC) is gaining interest, due to its actual and potential applications in the biomedical, cosmetics and textile industries. In this study, mechanical, thermal, and chemical properties of BC produced from a novel strain, isolated from a kombucha symbiotic culture of bacteria and yeast (SCOBY), were evaluated. The highest obtained yields with this strain, after a 10-day fermentation, were 496 ± 14 g/L (native hydrated) and 19 ± 1 g/L (dry). Compression, including relaxation, and traction tests were performed on BC membranes in a hydrated state. The tested material revealed a 3-phase compression behaviour with a compression modulus of 235 ± 50 Pa. In terms of relaxation in water, BC membranes showed plastic deformation past 50 % compression. Regarding BC membrane under traction, analysis showed a 1090 ± 410 kPa Young Modulus, a 50 ± 10 % Elongation at Break and a 270 ± 80 kPa Ultimate Tensile Strength (UTS). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicated that BC begins its degradation around 290 °C. Fourier-Transform Infrared spectroscopy (FTIR) of freeze-dried BC membranes confirmed the obtained biofilm to be BC. The results of this study provide valuable information on the potential applications of BC membranes in different industries including textile, biomedical and as a low-cost alternative to some synthetic polymers.

Biocontrol and Enzymatic Activity of Non-Saccharomyces Wine Yeasts: Improvements in Winemaking

Wine fermentation is a biochemical process carried out by a microbial consortium already present in the vineyard, including different species of fungi and bacteria that are in an ecological relationship with each other, so that their sequential growth causes the transformation of grape must into wine. Among the fungi, the unicellular ones, yeasts, stand out, including Saccharomyces cerevisiae, which is mainly responsible for driving alcoholic fermentation, as do other species present from the beginning of fermentation, known as non-Saccharomyces yeasts. These yeasts were previously considered harmful and undesirable; however, their role has recently been re-evaluated, mainly because they can provide products and effects that are of great value in achieving a quality final product. In this review, we discuss the role of non-Saccharomyces wine yeasts, firstly with regard to their biocontrol activity both on the grapes and during the vinification process and secondly with regard to their ability to produce enzymes, especially depolymerising ones. In this context, the possible biotechnological applications of these non-Saccharomyces yeasts to improve the health and quality of grape and wine production are addressed.

Effects of yeast culture on in vitro ruminal fermentation and microbial community of high concentrate diet in sheep.

This research aimed to investigate effects of different yeast culture (YC) levels on in vitro fermentation characteristics and bacterial and fungal community under high concentrate diet. A total of 5 groups were included in the experiment: control group without YC (CON), YC1 (0.5% YC proportion of substrate dry matter), YC2 (1%), YC3 (1.5%) and YC4 (2%). After 48h of fermentation, the incubation fluids and residues were collected to analyze the ruminal fermentation parameters and bacterial and fungal community. Results showed that the ruminal fluid pH of YC2 and YC4 groups was higher (P < 0.05) than that of CON group. Compared with CON group, the microbial protein, propionate and butyrate concentrations and cumulative gas production at 48h of YC2 group were significantly increased (P < 0.05), whereas an opposite trend of ammonia nitrogen and lactate was observed between two groups. Microbial analysis showed that the Chao1 and Shannon indexes of YC2 group were higher (P < 0.05) than those of CON group. Additionally, YC supplementation significantly decreased (P < 0.05) Succinivibrionaceae_UCG-001, Streptococcus bovis and Neosetophoma relative abundances. An opposite tendency of Aspergillus abundance was found between CON and YC treatments. Compared with CON group, the relative abundances of Prevotella, Succiniclasticum, Butyrivibrio and Megasphaera elsdenii were significantly increased (P < 0.05) in YC2 group, while Apiotrichum and unclassified Clostridiales relative abundances were decreased (P < 0.05). In conclusion, high concentrate substrate supplemented with appropriate YC (1%) can improve ruminal fermentation and regulate bacterial and fungal composition.