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Diguță, Camelia Filofteia, Constanța Mihai, Radu Cristian Toma, Carmen Cîmpeanu y Florentina Matei. "In Vitro Assessment of Yeasts Strains with Probiotic Attributes for Aquaculture Use". Foods 12, n.º 1 (26 de diciembre de 2022): 124. http://dx.doi.org/10.3390/foods12010124.
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This study aimed to investigate in vitro the probiotic potential of three yeasts strains (BB06, OBT05, and MT07) isolated from agro-food natural sources. Screening was performed, including several functional, technological, and safety aspects of the yeast strains, in comparison to a reference Saccharomyces boulardii, to identify the ones with suitable probiotic attributes in aquaculture. The yeast strains were identified by 5.8S rDNA-ITS region sequencing as Metschnikowia pulcherrima OBT05, Saccharomyces cerevisiae BB06, and Torulaspora delbrueckii MT07. All yeast strains were tolerant to different temperatures, sodium chloride concentrations, and wide pH ranges. S. cerevisiae BB06 showed a strong and broad antagonistic activity. Moreover, the S. cerevisiae strain exhibited a high auto-aggregation ability (92.08 ± 1.49%) and good surface hydrophobicity to hexane as a solvent (53.43%). All of the yeast strains have excellent antioxidant properties (>55%). The high survival rate in the gastrointestinal tract (GIT) can promote yeast isolates as probiotics. All yeast strains presented a resistance pattern to the antibacterial antibiotics. Non-hemolytic activity was detected. Furthermore, freeze-drying with cryoprotective agents maintained a high survival rate of yeast strains, in the range of 74.95–97.85%. According to the results obtained, the S. cerevisiae BB06 strain was found to have valuable probiotic traits.
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Hazra, Fahrizal. "Exploration of Pectin – Utilizing Yeast From Soil of Bogor and Wleri Fruit Orchards". Jurnal Hortikultura Indonesia 2, n.º 1 (23 de febrero de 2012): 43. http://dx.doi.org/10.29244/jhi.2.1.43-50.
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<p>There is a high demand on pectin–utilizing yeasts for industrial, agricultural and environmental purposes. Further exploration of yeast from various sources are important to enrich yeast culture collections. Nine yeast strains were isolated from various soil sources sampled based on biological sampling in Bogor and Central Java. Enriched media containing pectin as carbon sources was employed for isolation of the yeast. The isolated yeast were identified according to the methods described in monographs by Kreger – Van Rij (1984), Barnett et.al (2000), Guilliermond and Tanner (2006) . The strains isolated were taxonomically separated into 3 groups. Group I contains 3 strains, and this group is closely related to Candida tropicalis. Group II contains 4 strains, and this group is included in this genus Rhodotorula. Group III contain 2 strains, and this group is closely related to Williopsis saturnus, which is a synonym of Hansenula saturnus. Pectinolytic enzymes (Polygalacturonase) were produced by all of the tested strains. Polygalacturonase was produced as high as 1.7 U.ml-1 by strain no. 111 of group I, 1.7 U.ml-1 by strains no. 123 of group II, and 1.0 U.ml-1 by strain no. 211 of group III.</p><p><br />Key words : yeast, pectin, polygalacturonase</p>
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Alkay, Z., E. Dertli y M. Z. Durak. "Investigation of probiotic potential of yeasts isolated from sourdoughs from different regions of Turkey". Acta Alimentaria 50, n.º 4 (15 de noviembre de 2021): 610–19. http://dx.doi.org/10.1556/066.2021.00150.
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Abstract In this study, 14 yeast cultures from 62 isolates from traditional sourdoughs collected from 6 different regions of Turkey were selected by FT-IR identification and characterised to reveal their probiotic properties. Four yeast strains were genotypically identified and compared with FT-IR identification. In all analyses, it was observed that mostly Saccaromyces cerevisiae strain exhibited high hydrophobicity, auto-aggregation feature, and all yeast isolates in this study showed tolerance to 0.3%, even salt concentration. In addition, all yeast strains were susceptible to anti-yeasts agents, although they were resistant to all antibiotics used in the study. All selected yeast isolates exhibited high antimicrobial activity against the Staphylococcus aureus. In conclusion, this study investigated the potential probiotic properties of yeast strains isolated from sourdough.
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Păucean, Man, Chiş, Mureşan, Pop, Socaci, Mureşan y Muste. "Use of Pseudocereals Preferment Made with Aromatic Yeast Strains for Enhancing Wheat Bread Quality". Foods 8, n.º 10 (26 de septiembre de 2019): 443. http://dx.doi.org/10.3390/foods8100443.
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Usually, aromatic yeasts are designed to ferment wheat substrates for baking purposes but identification of new substrates for these strains and consequently new formulations for dough could lead to diversified bakery products with improved nutritional qualities and specific sensorial properties. The purpose of our study was to optimize the fermentation of quinoa and amaranth flours with non-conventional yeast strains in order to obtain a preferment with high potential in enhancing nutritional, textural and sensorial features of white wheat bread. Two biotypes of Saccharomyces cerevisiae yeast—a wine yeast strain and a beer yeast strain—commercialized for their aromatic properties were used. Both aromatic yeast strains revealed good performance on fermenting pseudocereal substrates. Utilization of the obtained preferment in white wheat breadmaking led to bread with higher protein, fibres, mineral, total polyphenols content, with specific texture and aroma profile and high consumers’ acceptability.
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Chen, Pei-Hua y Jui-Yu Chou. "Screening and Identification of Yeasts Antagonistic to Pathogenic Fungi Show a Narrow Optimal pH Range for Antagonistic Activity". Polish Journal of Microbiology 66, n.º 1 (30 de marzo de 2017): 101–6. http://dx.doi.org/10.5604/17331331.1234997.
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Microbes have evolved ways of interference competition to gain advantage over their ecological competitors. The use of secreted antagonistic compounds by yeast cells is one of the prominent examples. Although this killer behavior has been thoroughly studied in laboratory yeast strains, our knowledge of the antagonistic specificity of killer effects in nature remains limited. In this study, yeast strains were collected from various niches and screened for antagonistic activity against one toxin-sensitive strain of Saccharomyces cerevisiae and three pathogenic fungi. We demonstrate that some strains with antagonistic activity against these pathogenic fungi can be found in antagonist culture tests. These yeasts were identified as members of Trichosporon asahii, Candida stellimalicola, Wickerhamomyces anomalus, Ustilago esculenta, Aureobasidium pullulans, and Pichia kluyveri. The results indicated that the antagonistic activity of these killer yeasts has a narrow optimal pH range. Furthermore, we found that the antagonistic activity of some species is strain-dependent.
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Gargouri, Boutheina, Najla Mhiri, Fatma Karray, Fathi Aloui y Sami Sayadi. "Isolation and Characterization of Hydrocarbon-Degrading Yeast Strains from Petroleum Contaminated Industrial Wastewater". BioMed Research International 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/929424.
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Two yeast strains are enriched and isolated from industrial refinery wastewater. These strains were observed for their ability to utilize several classes of petroleum hydrocarbons substrates, such asn-alkanes and aromatic hydrocarbons as a sole carbon source. Phylogenetic analysis based on the D1/D2 variable domain and the ITS-region sequences indicated that strains HC1 and HC4 were members of the generaCandidaandTrichosporon, respectively. The mechanism of hydrocarbon uptaking by yeast,Candida,andTrichosporonhas been studied by means of the kinetic analysis of hydrocarbons-degrading yeasts growth and substrate assimilation. Biodegradation capacity and biomass quantity were daily measured during twelve days by gravimetric analysis and gas chromatography coupled with mass spectrometry techniques. Removal ofn-alkanes indicated a strong ability of hydrocarbon biodegradation by the isolated yeast strains. These two strains grew on long-chainn-alkane, diesel oil, and crude oil but failed to grow on short-chainn-alkane and aromatic hydrocarbons. Growth measurement attributes of the isolates, usingn-hexadecane, diesel oil, and crude oil as substrates, showed that strain HC1 had better degradation for hydrocarbon substrates than strain HC4. In conclusion, these yeast strains can be useful for the bioremediation process and decreasing petroleum pollution in wastewater contaminated with petroleum hydrocarbons.
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Castrillo, David, Noemi Neira y Pilar Blanco. "Saccharomyces cerevisiae Strain Diversity Associated with Spontaneous Fermentations in Organic Wineries from Galicia (NW Spain)". Fermentation 6, n.º 3 (15 de septiembre de 2020): 89. http://dx.doi.org/10.3390/fermentation6030089.
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Yeast play an essential role in wine quality. The dynamics of yeast strains during fermentation determine the final chemical and sensory characteristics of wines. This study aims to evaluate the Saccharomyces cerevisiae strains diversity in organic wineries from Galicia (NW Spain). Samples from spontaneous fermentations were taken in five wineries over three consecutive years (2013 to 2015). The samples were transported to the laboratory and processed following standard methodology for yeast isolation. S. cerevisiae strains were differentiated by mDNA-RFLPs. A total of 66 different strains were identified. Some of them presented a wide distribution and appeared in several wineries. However, other strains were typical from a specific winery. Similarity analysis using two different statistical tests showed significant differences in strain diversity among wineries. The results also revealed high biodiversity indexes; however, only some strains showed an important incidence in their distribution and frequency. Our findings confirmed that spontaneous fermentation favored the existence of a high S. cerevisiae strain diversity in organic wineries from Galicia. The presence of different yeasts during fermentation, specially winery-specific strains, contribute to increased wine complexity and differentiation.
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Yoshinaga, Masafumi, Stephanie How, Damien Blanco, Ian Murdoch, Matteo Grudny, Samantha Powers, Nelson Molina, Barry Rosen y Aaron Welch. "Directed Evolution of Saccharomyces cerevisiae for Increased Selenium Accumulation". Microorganisms 6, n.º 3 (6 de agosto de 2018): 81. http://dx.doi.org/10.3390/microorganisms6030081.
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Selenium-enriched yeast (selenium yeast) are one of the most popular sources of selenium supplementation used in the agriculture and human nutritional supplements industries. To enhance the production efficiency of selenium yeast, we sought to develop a method to identify, and ultimately select for, strains of yeast with enhanced selenium accumulation capabilities. Selenite resistance of four genetically diverse strains of Saccharomyces cerevisiae was assayed in various conditions, including varying carbon sources, nitrogen sources, and phosphate amounts, and they were correlated with selenium accumulation in a commercially relevant selenium-containing growth medium. Glycerol- and selenite-containing media was used to select for six yeast isolates with enhanced selenite resistance. One isolate was found to accumulate 10-fold greater selenium (0.13 to 1.4 mg Se g−1 yeast) than its parental strain. Glycerol- and selenium-containing medium can be used to select for strains of yeast with enhanced selenium accumulation capability. The methods identified can lead to isolation of industrial yeast strains with enhanced selenium accumulation capabilities that can result in greater cost efficiency of selenium yeast production. Additionally, the selection method does not involve the construction of transgenic yeast, and thus produces yeasts suitable for use in human food and nutrient supplements.
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Doan, Thi Kieu Tien, Thi Tuyet Nhung Do, Tri An Le, Hoang Hiep Tran, Thi Ngoc Mi Huynh, Ngoc Thanh Nguyen y Xuan Phong Huynh. "Isolation and selection of yeasts from soursop Annona muricata for wine fermentation". Ministry of Science and Technology, Vietnam 63, n.º 11 (25 de noviembre de 2021): 53–57. http://dx.doi.org/10.31276/vjst.63(11).53-57.
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Wine is a healthy drink and is becoming more diverse thanks to the substances with high biological activity and fully preserved the antioxidant capacity in the fruit after fermentation by yeast. This study aims to isolate yeasts that are capable of soursop fermentation. There were eight yeast strains isolated, in which five strains of yeasts NM1.1, NM1.2, NM2.1, NM3.1, NM3.2 are capable of fermenting soursop wine. Wine product after fermentation using strain NM1.1 with initial conditions of 22ºBrix, pH 4.5, supplemented yeast 1% (w/v) at room temperature (28-30ºC), in twelve-day, produced the ethanol content 10% v/v, methanol 1.304 g/l, and SO2 10.9 mg/l that meet Vietnamese standards (QCVN 6-3:2010/BYT).
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Cheraiti, Naoufel, St�phane Guezenec y Jean-Michel Salmon. "Redox Interactions between Saccharomyces cerevisiae and Saccharomyces uvarum in Mixed Culture under Enological Conditions". Applied and Environmental Microbiology 71, n.º 1 (enero de 2005): 255–60. http://dx.doi.org/10.1128/aem.71.1.255-260.2005.
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ABSTRACT Wine yeast starters that contain a mixture of different industrial yeasts with various properties may soon be introduced to the market. The mechanisms underlying the interactions between the different strains in the starter during alcoholic fermentation have never been investigated. We identified and investigated some of these interactions in a mixed culture containing two yeast strains grown under enological conditions. The inoculum contained the same amount (each) of a strain of Saccharomyces cerevisiae and a natural hybrid strain of S. cerevisiae and Saccharomyces uvarum. We identified interactions that affected biomass, by-product formation, and fermentation kinetics, and compared the redox ratios of monocultures of each strain with that of the mixed culture. The redox status of the mixed culture differed from that of the two monocultures, showing that the interactions between the yeast strains involved the diffusion of metabolite(s) within the mixed culture. Since acetaldehyde is a potential effector of fermentation, we investigated the kinetics of acetaldehyde production by the different cultures. The S. cerevisiae-S. uvarum hybrid strain produced large amounts of acetaldehyde for which the S. cerevisiae strain acted as a receiving strain in the mixed culture. Since yeast response to acetaldehyde involves the same mechanisms that participate in the response to other forms of stress, the acetaldehyde exchange between the two strains could play an important role in inhibiting some yeast strains and allowing the growth of others. Such interactions could be of particular importance in understanding the ecology of the colonization of complex fermentation media by S. cerevisiae.
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Sapsirisuk, Sirawich, Pirapan Polburee, Wanlapa Lorliam y Savitree Limtong. "Discovery of Oleaginous Yeast from Mountain Forest Soil in Thailand". Journal of Fungi 8, n.º 10 (18 de octubre de 2022): 1100. http://dx.doi.org/10.3390/jof8101100.
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As an interesting alternative microbial platform for the sustainable synthesis of oleochemical building blocks and biofuels, oleaginous yeasts are increasing in both quantity and diversity. In this study, oleaginous yeast species from northern Thailand were discovered to add to the topology. A total of 127 yeast strains were isolated from 22 forest soil samples collected from mountainous areas. They were identified by an analysis of the D1/D2 domain of the large subunit rRNA (LSU rRNA) gene sequences to be 13 species. The most frequently isolated species were Lipomyces tetrasporus and Lipomyces starkeyi. Based on the cellular lipid content determination, 78 strains of ten yeast species, and two potential new yeast that which accumulated over 20% of dry biomass, were found to be oleaginous yeast strains. Among the oleaginous species detected, Papiliotrema terrestris and Papiliotrema flavescens have never been reported as oleaginous yeast before. In addition, none of the species in the genera Piskurozyma and Hannaella were found to be oleaginous yeast. L. tetrasporus SWU-NGP 2-5 accumulated the highest lipid content of 74.26% dry biomass, whereas Lipomyces mesembrius SWU-NGP 14-6 revealed the highest lipid quantity at 5.20 ± 0.03 g L−1. The fatty acid profiles of the selected oleaginous yeasts varied depending on the strain and suitability for biodiesel production.
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Ceccato-Antonini, Sandra Regina, Luiz Carlos Moreira Cremonini y Christine Regenfuss. "'Killer' character of yeasts isolated from ethanolic fermentations". Scientia Agricola 56, n.º 3 (julio de 1999): 631–35. http://dx.doi.org/10.1590/s0103-90161999000300017.
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The number of killer, neutral and sensitive yeasts was determined from strains isolated from substrates related to alcoholic fermentations. From 113 isolates, 24 showed killer activity against NCYC 1006 (standard sensitive strain), while 30 were sensitive to NCYC 738 (standard killer strain), and 59 had no reaction in assays at 25-27°C. Two wild yeast strains of Saccharomyces cerevisiae and one of Candida colliculosa were tested against 10 standard killer strains and one standard sensitive strain in a cell x cell and well-test assays at four different pHs. None of the isolates displayed strong killer activity or were sensitive to the standard strains. All belonged to the neutral type. It was concluded that although the number of killer strains was high, this character cannot be used to protect ethanol fermentation processes against yeast contaminants like those which form cell clusters.
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Lhamo, Sonam y Karma Dorji. "Comparative Study on Physio-chemical and Organoleptic Attributes of Apple Wine Fermented from Local and Imported Yeasts". Bhutanese Journal of Agriculture 4, n.º 1 (24 de febrero de 2021): 122–36. http://dx.doi.org/10.55925/btagr.21.4111.
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With home micro-brewing on the rise, use of local indigenous yeast in the fermentation process is a prevalent practice in the country. The indigenous strain found in locally processed yeast can impart certain desirable flavours and aromas to the fermented wine. Furthermore, the use of antioxidant-rich wild herbs in local yeasts is reported to enhance the nutritional value of the wine. However, local yeasts are home-made under dubious processing conditions and cannot afford the advantage of being in a pure uncontaminated microbial form, unlike the commercial strains. This might affect the fermentative capability and compromise the end quality of the wine. Thus, this study was conducted to compare the organoleptic acceptability and physio-chemical properties (total soluble solid, alcohol by volume, transmittance value, pH and titratable acidity) of apple wine fermented by two local yeasts from Trashi Yangtse and Samtse districts in Bhutan and one commercial yeast manufactured in India. Both the local yeast strains seem to yield a wine with better appearance (clarity) and taste (sweetness) based on the sensory evaluation result. In terms of fermentative capability, the commercial strain had shorter fermentation time, but the local strains were able to yield wine with similar alcohol strength to the commercial strain. For the physio-chemical parameters, only pH and titratable acidity results were significantly different with the wine from local yeast from Samtse having a significantly higher malic acid content, while the wine from commercial yeast had lower pH. However, the results deduced from the sensory evaluation does not compliment the values obtained for Total Soluble Solute and clarity measurement. Besides, the difference in pH did not resonate with the taste perception (i.e., lowest pH wine considered sweeter). Thus, other flavour components might have a role to play in the sweet taste perception. Overall, the local strains showed promising results in terms of fermentation capability (ability to convert sugar to alcohol) and organoleptic attributes of the end wine in comparison to the commercial strain.
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Yu, Zhi-Hai, Gui-Dan Huang, Xiao-Yan Huang, Jiang-Hua Pu, Jia-Sheng Wu, Li-Rong Yue, William James Hardie, Xiao-Zhu Liu y Ming-Zheng Huang. "A Comparative Study of Yeasts for Rosa roxburghii Wine Fermentation". Fermentation 8, n.º 7 (30 de junio de 2022): 311. http://dx.doi.org/10.3390/fermentation8070311.
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Wine produced by fermentation of Chestnut rose (Rosa roxburghii) hips, known as cili (Chinese-Mandarin), in Guizhou province, and other places in China is becoming popular but there is limited knowledge of suitable yeast strains for its production. In this study, we first investigated the oenological properties of six commercial S. cerevisiae yeast strains (X16, F33, SH12, GV107, S102, RMS2), one commercial Saccharomyces cerevisiae var. bayanus (S103), one commercial, non-Saccharomyces yeast strain, Torulaspora delbrueckii Prelude, and one indigenous S. cerevisiae strain, CZ, for cili wine fermentation. We measured the key traits of each of the yeast strains, viz., sulfite resistance, flocculation, hydrogen sulfide production capacity, fermentation rate, and yeast growth curves. Subsequently, we measured the resultant wine characteristics, viz., pH, alcohol content, residual sugar, titratable acidity, volatile acidity, ascorbic acid content and headspace volatile compounds. The overall suitability of each yeast type was evaluated using a multi-factor, unweighted, scorecard. On that basis, RMS2 was the most suitable, and closely followed by CZ and X16. This study is the first comparative evaluation of yeasts for cili wine production and provides a preliminary guide for their selection.
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CAI, SHIYU y ABIGAIL B. SNYDER. "Thermoresistance in Black Yeasts Is Associated with Halosensitivity and High Pressure Processing Tolerance but Not with UV Tolerance or Sanitizer Tolerance". Journal of Food Protection 85, n.º 2 (6 de octubre de 2021): 203–12. http://dx.doi.org/10.4315/jfp-21-314.
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ABSTRACT Black yeasts can survive extreme conditions in food production because of their polyextremotolerant character. However, significant strain-to-strain variation in black yeast thermoresistance has been observed. In this study, we assessed the variability in tolerance to nonthermal interventions among a collection of food-related black yeast strains. Variation in tolerance to UV light treatment, high pressure processing (HPP), sanitizers, and osmotic pressure was observed within each species. The two strains previously shown to possess high thermotolerance, Exophiala phaeomuriformis FSL-E2-0572 and Exophiala dermatitidis YB-734, were also the most HPP tolerant but were the least halotolerant. Meanwhile, Aureobasidium pullulans FSL-E2-0290 was the most UV and sanitizer tolerant but had been shown to have relatively low thermoresistance. Fisher's exact tests showed that thermoresistance in black yeasts was associated with HPP tolerance and inversely with halotolerance, but no association was found with UV tolerance or sanitizer tolerance. Collectively, the relative stress tolerance among strains varied across interventions. Given this variation, different food products are susceptible to black yeast spoilage. In addition, different strains should be selected in challenge studies specific to the intervention. HIGHLIGHTS
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Waymark, Christopher y Annie E. Hill. "The Influence of Yeast Strain on Whisky New Make Spirit Aroma". Fermentation 7, n.º 4 (14 de diciembre de 2021): 311. http://dx.doi.org/10.3390/fermentation7040311.
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Flavour in Scotch malt whisky is a key differentiating factor for consumers and producers alike. Yeast (commonly Saccharomyces cerevisiae) metabolites produce a significant amount of this flavour as part of distillery fermentations, as well as ethanol and carbon dioxide. Whilst yeast strains contribute flavour, there is limited information on the relationship between yeast strain and observed flavour profile. In this work, the impact of yeast strain on the aroma profile of new make spirit (freshly distilled, unmatured spirit) was investigated using 24 commercially available active dried yeast strains. The contribution of alcoholic, fruity, sulfury and sweet notes to new make spirit by yeast was confirmed. Generally, distilling strains could be distinguished from brewing and wine strains based on aroma and ester concentrations. However, no statistically significant differences between individual yeast strains could be perceived in the intensity of seven aroma categories typically associated with whisky. Overall, from the yeast strains assessed, it was found that new make spirit produced using yeast strains marketed as ‘brewing’ strains was preferred in terms of acceptability rating.
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Caridi, A. "Selection of Calabrian strains of Saccharomyces sensu stricto for red wines". Acta Alimentaria 50, n.º 4 (15 de noviembre de 2021): 565–73. http://dx.doi.org/10.1556/066.2021.00119.
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Abstract Phenolic compounds provide important quality attributes to red wines interacting with the organoleptic impact of wines. Yeast mannoproteins can interact with grape phenolic compounds, responsible for colour and antioxidant activity of wines. The aim of this work was to perform oenological characterisation and specific selection of Calabrian strains of Saccharomyces sensu stricto. Among the considered traits, the aptitude of the yeast to preserve grape pigments and colour intensity was included. Among the best six yeast strains – Sc2731, Sc2742, Sc2756, Sc2773, Sc2774, and Sc2823 – strain Sc2742 exhibits the highest Folin–Ciocalteu index and strain Sc2774 the highest colour intensity. These two selected yeasts may be used as starter for the production of red wines in order to preserve grape pigments and colour intensity.
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Matti, Katrin, Beatrice Bernardi, Silvia Brezina, Heike Semmler, Christian von Wallbrunn, Doris Rauhut y Jürgen Wendland. "Characterization of Old Wine Yeasts Kept for Decades under a Zero-Emission Maintenance Regime". Fermentation 6, n.º 1 (11 de enero de 2020): 9. http://dx.doi.org/10.3390/fermentation6010009.
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All laboratories dealing with microbes have to develop a strain maintenance regime. While lyophilization based on freeze-drying may be feasible for large stock centers, laboratories around the world rely on cryopreservation and freezing of stocks at −80 °C. Keeping stocks at these low temperatures requires investments of several thousand kW/h per year. We have kept yeast stocks for several decades at room temperature on agar slants in glass reagent tubes covered with vaspar and sealed with cotton plugs. They were part of the Geisenheim Yeast Breeding Center stock collection that was started in the 19th century, well before −80 °C refrigeration technology was invented. Of these stocks, 60 tubes were analyzed and around one-third of them could be regrown. The strains were typed by sequencing of rDNA PCR fragments. Based on BlastN analyses, twelve of the strains could be assigned to Saccharomyces cerevisiae, two to S. kudriavzevii, and the others to Meyerozyma and Candida. The strains were used in white wine fermentations and compared to standard wine yeasts Uvaferm/GHM (Geisenheim) and Lalvin EC1118. Even with added nitrogen, the strains exhibited diverse fermentation curves. Post-fermentation aroma analyses and the determination of residual sugar and organic acid concentrations indicated that some strains harbor interesting flavor characteristics, surpassing current standard yeast strains. Thus, old strain collections bear treasures for direct use either in wine fermentations or for incorporation in yeast breeding programs aimed at improving modern wine yeasts. Furthermore, this provides evidence that low-cost/long-term culture maintenance at zero-emission levels is feasible.
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Hua, Sui-Sheng T., James L. Baker y Melanie Flores-Espiritu. "Interactions of Saprophytic Yeasts with anor Mutant of Aspergillus flavus". Applied and Environmental Microbiology 65, n.º 6 (1 de junio de 1999): 2738–40. http://dx.doi.org/10.1128/aem.65.6.2738-2740.1999.
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ABSTRACT The nor mutant of Aspergillus flavus has a defective norsolorinic acid reductase, and thus the aflatoxin biosynthetic pathway is blocked, resulting in the accumulation of norsolorinic acid, a bright red-orange pigment. We developed a visual agar plate assay to monitor yeast strains for their ability to inhibit aflatoxin production by visually scoring the accumulation of this pigment of the nor mutant. We identified yeast strains that reduced the red-orange pigment accumulation in the normutant. These yeasts also reduced aflatoxin accumulation by a toxigenic strain of A. flavus. These yeasts may be useful for reducing aflatoxin contamination of food commodities.
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Porras-Agüera, Moreno-García, Mauricio, Moreno y García-Martínez. "First Proteomic Approach to Identify Cell Death Biomarkers in Wine Yeasts during Sparkling Wine Production". Microorganisms 7, n.º 11 (8 de noviembre de 2019): 542. http://dx.doi.org/10.3390/microorganisms7110542.
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Apoptosis and later autolysis are biological processes which take place in Saccharomyces cerevisiae during industrial fermentation processes, which involve costly and time-consuming aging periods. Therefore, the identification of potential cell death biomarkers can contribute to the creation of a long-term strategy in order to improve and accelerate the winemaking process. Here, we performed a proteomic analysis based on the detection of possible apoptosis and autolysis protein biomarkers in two industrial yeast strains commonly used in post-fermentative processes (sparkling wine secondary fermentation and biological aging) under typical sparkling wine elaboration conditions. Pressure had a negatively effect on viability for flor yeast, whereas the sparkling wine strain seems to be more adapted to these conditions. Flor yeast strain experienced an increase in content of apoptosis-related proteins, glucanases and vacuolar proteases at the first month of aging. Significant correlations between viability and apoptosis proteins were established in both yeast strains. Multivariate analysis based on the proteome of each process allowed to distinguish among samples and strains. The proteomic profile obtained in this study could provide useful information on the selection of wine strains and yeast behavior during sparkling wine elaboration. Additionally, the use of flor yeasts for sparkling wine improvement and elaboration is proposed.
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Zhang, Jing, Wenting Shen, Zhiyuan Cai, Kaiyue Chen, Qi Ouyang, Ping Wei, Wei Yang y Chunxiong Luo. "Microfluidic-Enabled Multi-Cell-Densities-Patterning and Culture Device for Characterization of Yeast Strains’ Growth Rates under Mating Pheromone". Chemosensors 10, n.º 4 (8 de abril de 2022): 141. http://dx.doi.org/10.3390/chemosensors10040141.
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Yeast studies usually focus on exploring diversity in terms of a specific trait (such as growth rate, antibiotic resistance, or fertility) among extensive strains. Microfluidic chips improve these biological studies in a manner of high throughput and high efficiency. For a population study of yeast, it is of great significance to set a proper initial cell density for every strain under specific circumstances. Herein, we introduced a novel design of chip, which enables users to load cells in a gradient order (six alternatives) of initial cell density within one channel. We discussed several guidelines to choose the appropriate chamber to ensure successful data recording. With this chip, we successfully studied the growth rate of yeast strains under a mating response, which is crucial for yeasts to control growth behaviors for prosperous mating. We investigated the growth rate of eight different yeast strains under three different mating pheromone levels (0.3 μM, 1 μM, and 10 μM). Strains with, even, a six-fold in growth rate can be recorded, with the available data produced simultaneously. This work has provided an efficient and time-saving microfluidic platform, which enables loading cells in a pattern of multi-cell densities for a yeast population experiment, especially for a high-throughput study. Besides, a quantitatively analyzed growth rate of different yeast strains shall reveal inspiring perspectives for studies concerning yeast population behavior with a stimulated mating pheromone.
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Ianieva, O. D., M. O. Fomina, T. V. Babich, G. P. Dudka y V. S. Pidgorskyi. "Evaluation of Non-Conventional Yeasts Isolated from Rotten Wood for Hydrolytic Activities and Xylose Fermentation". Mikrobiolohichnyi Zhurnal 84, n.º 4 (17 de enero de 2023): 88–97. http://dx.doi.org/10.15407/microbiolj84.04.088.
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Hydrolysis of lignocellulose to fermentable sugars and their subsequent conversion to ethanol remain great challenges in the biofuel industry. Rotten wood is first colonized by bacteria and molds that possess strong hydrolases. Yeasts are also an important group of microorganisms that may participate in wood hydrolysis. Decaying wood could provide a rich natural reservoir of yeasts possessing promising hydrolytic activities, including xylanases, cellulases, β-glucosidases, or abilities essential for the fermentation of pentose sugars derived from lignocellulose degradation, especially xylose. Therefore, the aim of this work was to screen yeasts isolated from rotten wood samples for the production of hydrolytic enzymes directed at lignocellulose components and the ability to ferment xylose, L-arabinose, and cellobiose. Methods. Yeast strains were isolated from 22 samples of rotten wood and identified by phenotypic characteristics according to Kurtzman et al. Hydrolytic properties and the ability of the isolated strains to ferment xylose, L-arabinose, and cellobiose were determined using conventional methods. Results. 30 strains of yeasts and yeast-like micromycetes were isolated from 22 samples of rotten wood in the Holosiivskyi Forest, Kyiv. Based on phenotypic properties, most of the isolated yeasts belonged to ascomycetous yeasts and were represented by the following genera: Candida (8 strains), Debaryomyces (5 strains), Kluyveromyces (5 strains), Pichia (5 strains), Scheffersomyces (2 strains), Lachancea, Hanseniaspora, Saccharomyces, and Geotrichum/Galactomyces. A strain of yeast-like non-photosynthetic alga Prototheca sp. was also detected. Most of the isolated microfungi (66.6% isolates) exhibited extracellular β-glucosidase activity, two Candida tropicalis strains possessed weak pectinase and xylanase activity. None of the isolates demonstrated extracellular cellulase activity. Two yeast strains preliminarily identified as Scheffersomyces stipitis were able to ferment xylose at a concentration of 20—100 g/L over a wide temperature range up to 37°C. Acetic acid at 0.25—1% (v/v) concentration resulted in the complete inhibition of xylose fermentation. Ethanol production from xylose up to 6 g/L was observed under the microaerobic fermentation conditions for 24 hr at the substrate concentration 40 g/L, but the subsequent fermentation resulted in decreasing ethanol concentration presumably due to ethanol re-assimilation. None of the isolated strains was capable of fermenting cellobiose or L-arabinose under the microaerobic conditions. Conclusions. This work provides the characterization of yeast microbiota of rotten wood that was represented predominantly by ascomycetous yeasts. The dominant extracellular hydrolytic activity of the isolates was β-glucosidase. This is the first report on the isolation of xylose-fermenting yeasts Scheffersomyces stipitis in Ukraine, which comprised 7% of all the microfungi isolated from rotten wood.
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Tan, Mélissa, Yanis Caro, Juliana Lebeau, Alain Shum-Cheong-Sing, Jean Marie François, Thierry Regnier y Thomas Petit. "Screening for Volatile α-Unsaturated Ester-Producing Yeasts from the Feces of Wild Animals in South Africa". Life 12, n.º 12 (30 de noviembre de 2022): 1999. http://dx.doi.org/10.3390/life12121999.
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α-unsaturated esters are fruity-aromatic compounds which are largely spread in the volatilome of many different fruits, but they are rarely found in the volatilome of yeasts. The yeast S. suaveolens has been recently shown to produce relatively high amounts of α-unsaturated esters and it appears to be an interesting model for the production of these compounds. This study aimed to isolate new α-unsaturated ester-producing yeasts by focusing on strains displaying a similar metabolism to S. suaveolens. While the production of α-unsaturated esters by S. suaveolens is believed to be closely related to its ability to grow on media containing branched-chain amino acids (isoleucine, leucine and valine) as the sole carbon source (ILV+ phenotype), in this study, an original screening method was developed that selects for yeast strains displaying ILV+ phenotypes and is able to produce α-unsaturated esters. Among the 119 yeast strains isolated from the feces of 42 different South African wild animal species, 43 isolates showed the ILV+ phenotype, among which 12 strains were able to produce α-unsaturated esters. Two interesting α-unsaturated esters were detected in two freshly isolated strains, both identified as Galactomyces candidus. These new esters were detected neither in the volatilome of the reference strain S. suaveolens, nor in any other yeast species previously studied for their aroma production. This work demonstrated the efficiency of an original method to rapidly screen for α-unsaturated ester-producing yeasts. In addition, it demonstrated that wild animal feces are interesting resources to isolate novel strains producing compounds with original aromas.
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García, Esteve-Zarzoso, Crespo, Cabellos y Arroyo. "Influence of Native Saccharomyces cerevisiae Strains from D.O. “Vinos de Madrid” in the Volatile Profile of White Wines". Fermentation 5, n.º 4 (30 de octubre de 2019): 94. http://dx.doi.org/10.3390/fermentation5040094.
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Yeasts during alcoholic fermentation form a vast number of volatile compounds that significantly influence wine character and quality. It is well known that the capacity to form aromatic compounds is dependent on the yeast strain. Thus, the use of native yeast strains, besides promoting biodiversity, encourages the conservation of regional sensory properties. In this work, we studied the volatile profile of Malvar wines fermented with 102 Saccharomyces cerevisiae yeast strains, isolated from vineyards and cellars belonging to the D.O. “Vinos de Madrid”. The wines elaborated with different S. cerevisiae showed a good classification by cellar of origin. Additionally, seven sensory descriptors have helped to classify the wines depending on their predominant aromatic character. Twenty-nine Saccharomyces strains, belonging to five of six cellars in the study, were characterized by producing wines with a fruity/sweet character. Floral, solvent, and herbaceous descriptors are more related to wines elaborated with Saccharomyces strains from organic cellars A, E, and F. Based on these findings, winemakers may use their best native S. cerevisiae strains, which add personality to their wine. Therefore, this study contributes to promoting the use of native Saccharomyces yeasts in winemaking.
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Chigusa, K., T. Hasegawa, N. Yamamoto y Y. Watanabe. "Treatment of wastewater from oil manufacturing plant by yeasts". Water Science and Technology 34, n.º 11 (1 de diciembre de 1996): 51–58. http://dx.doi.org/10.2166/wst.1996.0262.
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Nine strains of yeasts capable of decomposing oil were isolated in order to directly treat wastewater from oil manufacturing plants with no pretreatment. The oil decomposing ability of these yeast strains was evaluated in terms of lipase activity and β-oxidation activity. Since the mixture of the isolated yeasts was superior to any single strain in the oil removal rate, a pilot plant utilizing the mixed strains was operated at the soybean oil factory. Following a one year pilot plant operation, it was found that 10,000 mgℓ−1 of hexane extracts in the raw wastewater could be reduced by yeast treatment to a concentration of about 100 mgℓ−1. This concentration was further treated by the activated sludge process to 2 mgℓ−1. The dominant yeasts in the pilot plant were found to form mycelial or pseudomycelial pellets and have low fermenting ability.
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de Figueiredo, Catarina M., Daniella H. Hock, Débora Trichez, Maria de Lourdes B. Magalhães, Mario L. Lopes, Henrique V. de Amorim y Boris U. Stambuk. "High Foam Phenotypic Diversity and Variability in Flocculant Gene Observed for Various Yeast Cell Surfaces Present as Industrial Contaminants". Fermentation 7, n.º 3 (24 de julio de 2021): 127. http://dx.doi.org/10.3390/fermentation7030127.
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Many contaminant yeast strains that survive inside fuel ethanol industrial vats show detrimental cell surface phenotypes. These harmful effects may include filamentation, invasive growth, flocculation, biofilm formation, and excessive foam production. Previous studies have linked some of these phenotypes to the expression of FLO genes, and the presence of gene length polymorphisms causing the expansion of FLO gene size appears to result in stronger flocculation and biofilm formation phenotypes. We performed here a molecular analysis of FLO1 and FLO11 gene polymorphisms present in contaminant strains of Saccharomyces cerevisiae from Brazilian fuel ethanol distilleries showing vigorous foaming phenotypes during fermentation. The size variability of these genes was correlated with cellular hydrophobicity, flocculation, and highly foaming phenotypes in these yeast strains. Our results also showed that deleting the primary activator of FLO genes (the FLO8 gene) from the genome of a contaminant and highly foaming industrial strain avoids complex foam formation, flocculation, invasive growth, and biofilm production by the engineered (flo8∆::BleR/flo8Δ::kanMX) yeast strain. Thus, the characterization of highly foaming yeasts and the influence of FLO8 in this phenotype open new perspectives for yeast strain engineering and optimization in the sugarcane fuel-ethanol industry.
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Into, Parichat, Ana Pontes, José Paulo Sampaio y Savitree Limtong. "Yeast Diversity Associated with the Phylloplane of Corn Plants Cultivated in Thailand". Microorganisms 8, n.º 1 (7 de enero de 2020): 80. http://dx.doi.org/10.3390/microorganisms8010080.
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The ecology and diversity of phylloplane yeasts is less well understood in tropical regions than in temperate ones. Therefore, we investigated the yeast diversity associated with the phylloplane of corn, an economically important crop in Thailand, by a culture-dependent method. Thirty-six leaf samples were collected and 217 yeast strains were isolated by plating leaf-washings. The strains were grouped by PCR-fingerprinting and representative strains were identified by analysis of the D1/D2 domain of the large subunit rRNA gene. In total, 212 strains were identified within 10 species in the Ascomycota and 32 species in the Basidiomycota. Five strains represented potential new species in the Basidiomycota, one strain was recently described as Papiliotrema plantarum, and four strains belonged to the genera Vishniacozyma and Rhodotorula. A higher number of strains in the Basidiomycota (81.6%) was obtained. Hannaella sinensis was the species with the highest occurrence. Principal coordinates analysis ordinations of yeast communities revealed that there were no differences in the similarity of the sampling sites. The estimation of the expected species richness showed that the observed species richness was lower than expected. This work indicated that a majority of yeast associated with the phylloplane of corn plant belongs to the phylum Basidiomycota.
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Yi, Xiunan y Hal S. Alper. "Considering Strain Variation and Non-Type Strains for Yeast Metabolic Engineering Applications". Life 12, n.º 4 (30 de marzo de 2022): 510. http://dx.doi.org/10.3390/life12040510.
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A variety of yeast species have been considered ideal hosts for metabolic engineering to produce value-added chemicals, including the model organism Saccharomyces cerevisiae, as well as non-conventional yeasts including Yarrowia lipolytica, Kluyveromyces marxianus, and Pichia pastoris. However, the metabolic capacity of these microbes is not simply dictated or implied by genus or species alone. Within the same species, yeast strains can display distinct variations in their phenotypes and metabolism, which affect the performance of introduced pathways and the production of interesting compounds. Moreover, it is unclear how this metabolic potential corresponds to function upon rewiring these organisms. These reports thus point out a new consideration for successful metabolic engineering, specifically: what are the best strains to utilize and how does one achieve effective metabolic engineering? Understanding such questions will accelerate the host selection and optimization process for generating yeast cell factories. In this review, we survey recent advances in studying yeast strain variations and utilizing non-type strains in pathway production and metabolic engineering applications. Additionally, we highlight the importance of employing portable methods for metabolic rewiring to best access this metabolic diversity. Finally, we conclude by highlighting the importance of considering strain diversity in metabolic engineering applications.
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Eustace, Rosanne y R. J. Thornton. "Selective hybridization of wine yeasts for higher yields of glycerol". Canadian Journal of Microbiology 33, n.º 2 (1 de febrero de 1987): 112–17. http://dx.doi.org/10.1139/m87-019.
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Wines that are lacking in body may be improved by the presence of greater amounts of glycerol. Wine yeast strains vary in their ability to produce glycerol. A programme of hybridizing yeast strains while selecting for increased production of glycerol was undertaken. Three generations of hybridization resulted in yeast strains which produced 10–11 g glycerol/L compared with 3.0–6.6 g/L produced by the wine yeast strains of the original breeding stock. Industrial-scale winemaking confirmed the ability of two hybrid strains to produce similar amounts of glycerol to those observed in laboratory-scale fermentations. The activity of the enzyme glycerol-3-phosphate dehydrogenase was measured in crude extracts of two breeding stock wine yeasts and in two final generation hybrid strains. The observed activities were lower in the products of the hybridization programme than in the original wine yeast strains. Two alternative explanations are suggested. (i) Selective hybridization may select for the alleles of the gene which codes for an alcohol dehydrogenase I isozyme which has a lower activity resulting in increased glycerol production. (ii) Phospholipid synthesis is reduced and the glycerol-3-phosphate, which is the major precursor of phospholipids in yeasts, accumulates as glycerol.
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Lachance, Marc-André, Carlos A. Rosa, Enrique Javier Carvajal, Larissa F. D. Freitas y Jane M. Bowles. "Saccharomycopsis fodiens sp. nov., a rare predacious yeast from three distant localities". International Journal of Systematic and Evolutionary Microbiology 62, Pt_11 (1 de noviembre de 2012): 2793–98. http://dx.doi.org/10.1099/ijs.0.043109-0.
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Three strains representing a novel yeast species were recovered as part of independent collections from flower-associated nitidulid beetles in Australia, Costa Rica and the Galapagos Islands, Ecuador. Analysis of the D1/D2 domains of the large subunit rRNA gene indicated that the species belongs to the genus Saccharomycopsis, although the formation of ascospores was not observed. The yeast is capable of necrotrophic parasitism by means of infection pegs when mixed with other yeasts or filamentous fungi. Of particular interest is the fact that despite the large distances separating the isolation sites of the three strains, other strains of the species have not been recovered in other samples of flower-associated nitidulids even though these habitats have been sampled extensively. It is suggested that the dispersal of the yeast may be linked to human historical factors. The name Saccharomycopsis fodiens sp. nov. is proposed for the yeast. The type strain is UWOPS 95-697.4T ( = CBS 8332T = NRRL Y-48786T).
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Kunicka-Styczyńska, A. y E. Pogorzelski. "l-Malic Acid Effect on Organic Acid Profiles and Fermentation By-products in Apple Wines". Czech Journal of Food Sciences 27, Special Issue 1 (24 de junio de 2009): S228—S231. http://dx.doi.org/10.17221/1063-cjfs.
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Industrial wine yeasts Saccharomyces bayanus and two interspecies hybrids (S. cerevisiae × S. bayanus) were checked for their suitability for fermentation of apple musts with different L-malic acid content (4, 7 and 11 g/l). The fermentation profiles including main organic acids, acetaldehyde, diacetyl, glycerol, esters and polyphenols were presented. The results were obtained by HPLC method (organic acids, acetaldehyde, glycerol, diacetyl), GC (esters), colorimetrically (polyphenols) and enzymatically (L-malic acid, ethanol). Although the fermentation profiles of wines were characteristic for specific yeast strains, similarities in organic acid profiles of wines fermented by S. bayanus and its hybrid S-779/25 were noted. In all the tested wines L-malic, pyruvic and citric acids were dominant. Statistical analysis of all wine parameters indicates that yeast strains respond individually to different acidities of the fermentation environment. In order to choose the right yeast strain for the fermentation of acidic musts, information about fermentation profiles should be included in the collection certificate of yeast strains.
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Nguyen Thu, Hoai, Hong Do Thi Thu, Cuong Ngo Cao, Thinh Do Tat y V. N. Sereda. "Impact of black yeasts on the durability of polyurethane foam in tropical conditions in Vietnam". E3S Web of Conferences 169 (2020): 02007. http://dx.doi.org/10.1051/e3sconf/202016902007.
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Polyurethane (PU) is a material that is widely used in industries. However, tropical climatic conditions in Vietnam often make the durability of PU lower than temperate climatic conditions. One of the causes of this problem is the biodegradation of microorganisms. In this study, biological characteristics of black yeast on PU is evaluated, thereby, initially assessing the impact of black yeast on the durability of PU in tropical conditions. Ten strains of black yeast were isolated from used PU foam samples in Vietnam. These black yeast strains were tested for enzyme activity including: urease activity, protease activity, polyurethanase activity. There were two strains selected to identify based on sequence analysis of the ITS1/ITS2 region, they belong to genus Aureobasidium. VN1Y3 was strain selected for biodegradability testing of PU foam samples. After 28 days of testing, the PU foam samples that have been infected with black yeasts have a change compared to the control in terms of color, surface, tensile strength, elongation. Research results have showed the impact of black yeast on the durability of PU.
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Gomes, Fátima de Cássia Oliveira, Roberta Amália de Carvalho Araújo, Patrícia Silva Cisalpino, Elizabeth Spangler Andrade Moreira, Carlos Leomar Zani y Carlos Augusto Rosa. "Comparison between two selected Saccharomyces cerevisiae strains as fermentation starters in the production of traditional cachaça". Brazilian Archives of Biology and Technology 52, n.º 2 (abril de 2009): 449–55. http://dx.doi.org/10.1590/s1516-89132009000200023.
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Two Saccharomyces cerevisiae strains were tested as the starter yeasts in a traditional cachaça distillery. The strains used were S. cerevisiae UFMG-A829, isolated from a cachaça fermentation process, and S. cerevisiae K1-V1116, obtained from the wine industry. The permanence of each strain in the fermentation must was determined by RAPD (Random Amplified Polymorphic DNA)-PCR, with primer M13. Both yeast strains were prevalent in the vats for approximately 30 days. Indigenous non-Saccharomyces and indigenous S. cerevisiae strains were isolated in lower counts during the fermentation period. Indigenous S. cerevisiae strains were molecularly distinct when compared to the starter yeasts. The two yeasts appeared promising starter yeasts in the fermentation process to produce traditional cachaça.
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Tournas, VH y EJ Katsoudas. "Effect of CaCl2 and Various Wild Yeasts From Plant Origin on Controlling Penicillium expansum Postharvest Decays in Golden Delicious Apples". Microbiology Insights 12 (enero de 2019): 117863611983764. http://dx.doi.org/10.1177/1178636119837643.
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The biocontrol potential of four wild yeast strains ( Meyerozyma guilliermondii – strain YS-1, Meyerozyma caribbica – strain YS-3, Cryptococcus albidus – strain YS-4, and Cryptococcus sp. – strain YS-5) against Penicillium expansum was studied in vivo (on Golden Delicious apples). The test yeasts were applied to the fruits alone as well as in combination with 2% CaCl2. Treated apples were stored at room temperature (~21°C) for up to 2 weeks or under refrigeration (3°C) for up to 2 months. Candida oleophila was used as positive biocontrol agent. Biocontrol activities were expressed as percentages of lesion size reduction caused by the test yeasts or by test yeasts + CaCl2 as compared with decays on apples treated with P. expansum alone. All strains tested during this study showed some degree of biocontrol activity against P. expansum. When the test yeasts were applied alone, they effected moderate pathogen inhibition reducing the decay size by 28% to 52% at day 7 and 11% to 27% at day 14 of incubation at room temperature. When the treated apples were stored at 3°C, lesion size reduction was between 48% and 63% after 1 month and 24% to 41% after 2 months of incubation. Addition of CaCl2 to yeast suspensions facilitated much higher pathogen inhibition. At room temperature, lesion size reduction ranged between 74% and 77% during the first week. After 2 weeks of incubation, decays on yeast + CaCl2-treated apples were still substantially smaller (49%-73% lower) than those on apples treated with P. expansum alone. At refrigeration, lesion size reduction ranged between 76% and 92% in the first month of storage and between 75% and 87% after 2 months of incubation. Decay incidence was 75% to 100% in apples stored at room temperature and 30% to 85% in those kept under refrigeration. The inhibitory activities of the wild yeast strains were similar to those exhibited by C. oleophila for the most part. These strains, when combined with CaCl2, showed high potential as biocontrol agents against P. expansum on stored apples.
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De Bellis, Palmira, Carlo Rizzello, Angelo Sisto, Francesca Valerio, Stella Lonigro, Amalia Conte, Valeria Lorusso y Paola Lavermicocca. "Use of a Selected Leuconostoc Citreum Strain as a Starter for Making a “Yeast-Free” Bread". Foods 8, n.º 2 (13 de febrero de 2019): 70. http://dx.doi.org/10.3390/foods8020070.
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The aim of this study was the characterization and selection of bacterial strains suitable for the production of a “yeast-free” bread. The strains Leuconostoc citreum C2.27 and Weissella confusa C5.7 were selected for their leavening and acidification capabilities and individually used as starters in bread-making tests. Liquid type-II sourdoughs, singly inoculated with the two selected strains, were characterized and employed for bread-making, through the set-up of a biotechnological protocol without the use of baker’s yeast as a leavening agent. Aiming to verify the ability of the selected strains to dominate the fermentation process, bacteria and yeasts were isolated from liquid sourdoughs and doughs, genetically characterized and identified. Both the selected strains were suitable for the production of bread, even if L. citreum C2.27 showed the highest leavening capacity and was able to dominate the dough microbiota. The effects of different salt concentrations on the selected strain performances were also investigated. The applicability of the developed protocol, adapted for the production of the typical Apulian bread, “puccia”, and the suitability of the strain L. citreum C2.27 were confirmed at pilot scale in an industrial bakery. The puccia bread, which was produced with the liquid sourdough fermented with L. citreum C2.27, without baker’s yeast and salt, was similar in appearance to the conventional product containing baker’s yeast and was judged positively by a sensory analysis.
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Zabukovec, Polona, Neža Čadež y Franc Čuš. "Isolation and Identification of Indigenous Wine Yeasts and their Use in Alcoholic Fermentation". Food Technology and Biotechnology 58, n.º 3 (11 de agosto de 2020): 337–47. http://dx.doi.org/10.17113/ftb.58.03.20.6677.
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Research background. In our study, spontaneous alcoholic fermentations were carried out to isolate non-Saccharomyces and Saccharomyces yeasts from grape must from different wine growing regions in Slovenia. Additionally, the diversity of native Saccharomyces cerevisiae strains was evaluated during the process. Experimental approach. During spontaneous alcoholic fermentations the yeast population of non-Saccharomyces and Saccharomyces yeasts was sampled. We used eleven microsatellite markers to determine the genetic diversity of S. cerevisiae strains. In addition, different proportions of the indigenous strains of S. cerevisiae, Hanseniaspora uvarum and Starmerella bacillaris were tested for their possible use in inoculated AF by monitoring the course of alcoholic fermentation and measuring the content of aroma compounds in wine. Results and conclusions. Sequencing of the ITS regions of ribosomal DNA showed that of 64 isolates 46 strains represent S. cerevisiae and 18 strains belong to non-Saccharomyces yeasts. The identified non-Saccharomyces yeast species were H. uvarum, Pichia kudriavzevii, Saturnispora diversa and S. bacillaris. The dendrogram grouped S. cerevisiae strains into 14 groups. The number of S. cervisiae strains isolated from the musts was 10 (Posavje), 11 (Podravje) and 25 (Primorska vine-growing region). On the other hand, the inoculated AF, in which the native S. cerevisiae strain predominated over H. uvarum and S. bacillaris, gave the most promising result due to the highest alcohol content, the lowest acetic acid concentration and the significantly higher concentrations of volatile thiols (3MHA and 3MH), 2-methylpropanol, 2-methylbutanol, 3-methylbutanol and 2-phenyl ethanol in the wine produced. Novelty and scientific contribution. We confirmed the potential use of indigenous S. cerevisiae and non-Saccharomyces yeasts in inoculated AFs, which allows the positive properties of the yeast strains to be expressed and good quality wines to be produced. Thus, the results are encouraging for winemakers to create different wine styles associated with a particular terroir using indigenous yeasts.
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Graf, Barbara, Thomas Adam, Edith Zill y Ulf B. Göbel. "Evaluation of the VITEK 2 System for Rapid Identification of Yeasts and Yeast-Like Organisms". Journal of Clinical Microbiology 38, n.º 5 (2000): 1782–85. http://dx.doi.org/10.1128/jcm.38.5.1782-1785.2000.
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The new VITEK 2 system is a fully automated system dedicated to the identification and susceptibility testing of microorganisms. In conjunction with the VITEK ID-YST card the VITEK 2 system allows the identification of clinically important yeasts and yeast-like organisms in 15 h due to a sensitive fluorescence-based technology. The ID-YST card consists of 47 biochemical reactions. The database comprises 51 taxa, including newly described species. In this study we evaluated the reliability of the VITEK ID-YST card for the identification of yeasts and yeast-like organisms encountered in a clinical microbiology laboratory. A total of 241 strains representing 21 species were studied. The strains were isolated from clinical samples within a period of 60 days prior to the identification. The tests were performed using 24-h to 55-h subcultures on Sabouraud-gentamicin-chloramphenicol agar. Each strain was tested in parallel using the ID 32C strip as a comparison method combined with microscopic morphology and an agglutination test for C. krusei. Overall, 222 strains (92.1%) were unequivocally identified including 11 isolates (4.6%) identified with low discrimination resolved by simple additional tests. Ten strains (4.1%) for which results were given with low discrimination could not be unequivocally identified with supplemental tests, 4 strains (1.7%) were misidentified and 5 strains (2.1%) could not be identified. In conclusion, we found that the VITEK 2 system is a rapid and accurate method for the identification of medically important yeasts and yeast-like organisms.
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Thao, Pham Nguyen Phuong, Bui Thi Thanh Thuy, Le Bui Trung Trinh y Nguyen My Phi Long. "Screening yeast strains for alcohol fermentation from the dried traditional yeast". ENGINEERING AND TECHNOLOGY 8, n.º 1 (17 de agosto de 2020): 92–105. http://dx.doi.org/10.46223/hcmcoujs.tech.en.8.1.908.2018.
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Methods to produce rice alcohol by dried traditional yeast are unstable because the yeast system in dried traditional yeast has depended on nature and not been controlled. In this study, a total of 15 different kinds of dried traditional yeast were prepared and screened. Each yeast strain was evaluated by analyzing its fermentation property and alcohol tolerance. There are 19 yeast strains were isolated and their growth conditions and ethanol producing properties were examined. Results showed that three strains S1, BT, BL3 grew and produced ethanol at temperature 28-30oC, and pH 5-5.5. Especially, high concentration ethanol tolerance ability of the three strains was at 8-18%. Our results showed that these strains were valuable microorganisms and could be utilized as a basis for further study of dried traditional yeast in traditional alcoholic beverages.
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Luo, Shao Hua, Yong Wen Huang, An Chen y Jia Ling Wang. "Domestication and Screening of Saccharomyces Cerevisiae Strain Resistant to Inhibitors in Lignocellulosic Hydrolysates by Acclimatizing Inhibitory". Applied Mechanics and Materials 448-453 (octubre de 2013): 1581–86. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.1581.
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In order to find the strains which can produce high ethanol yield as well as tolerate inhibitors on the lignocellulosic hydrolysates for developing the renewable bioenergy, the sepecial yeast must be explored. After acclimatizing 23 days and using five different acclimation media with sequential increase in the concentration of inhibitory compounds , a kind ofsaccharomyces cerevisiaestrain resistant to inhibitors was obtained . When the yeast resistant to drug and the parent strain grew in the same media which contained several inhibitory compounds 3.2 g/L acetic acid , 0.8 g/L furfural , 0.4 g/L formic acid , the new yeasts maximal ethanol yield can reach 0.428 g/g , up to 85.6% of theoretical ethanol yield. Compared with drug resistant yeast , the parent strains maximal ethanol production yield only can reach 0.246 g/g , up to 52.8% of theoretical ethanol yield . After 5 continuous ages , the average ability of producing ethanol was stable. Compared with parent strain, the yeast resistant to drug had good ability to ferment glucose and produce ethanol as well as tolerate inhibitors .The new yeast has extensive application prospect in the bioethanol production.
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Eisikowitch, D., M. A. Lachance, P. G. Kevan, S. Willis y D. L. Collins-Thompson. "The effect of the natural assemblage of microorganisms and selected strains of the yeast Metschnikowia reukaufii in controlling the germination of pollen of the common milkweed Asclepias syriaca". Canadian Journal of Botany 68, n.º 5 (1 de mayo de 1990): 1163–65. http://dx.doi.org/10.1139/b90-147.
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The yeast Metschnikowia reukaufii is a natural contaminant of nectar and is vectored to the flowers of the field milkweed Asclepias syriaca by insects, some of which are pollinators of the plants. In its natural habitat, the yeast inhibits the germination of the milkweed's pollen, which normally uses nectar in the stigmatic cavity for germination. This inhibition is irreversible after about 8 h of exposure to the yeasts. Two selected strains of the yeast were isolated and investigated for their effects on pollen germination in vitro. The two strains, and their mixture, affected pollen germination adversely by reducing its amount and vigour and causing any pollen tubes that were produced to burst: One strain was more virulent than the other, and the mixture seemed to have an additive effect. The strains may be more efficacious than the natural assemblage of microbes in disrupting fertilization of milkweed flowers because they cause the immediate death (bursting) of the growing microgametophyte (pollen and tube). Key words: yeasts, pollen germination, milkweed, Metschnikowia reukaufii, Asclepias syriaca.
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Nitiema-Yefanova, Svitlana, Cokou Pascal Agbangnan Dossa, Virginie Gbohaïda, Rose Estelle Kanfon, Issiakou Mossi y Buscotin Horax Beakou. "Fermented Parkia biglobosa seeds as a nitrogen source supplementation for bioethanol production from cashew apple juice". International Journal of Biological and Chemical Sciences 14, n.º 9 (26 de marzo de 2021): 3441–54. http://dx.doi.org/10.4314/ijbcs.v14i9.37.
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Nutritional requirements in the fermentation process are key parameters for optimal yeast development and ethanol production. Natural nutritional supplements rich in nitrogen, phosphorus, sulfur, and micro-elements can improve the performance of yeasts and offer a sustainable, cost-effective, and environmentally friendly alternative to synthetic chemicals. This study aimed at investigating the effect of a natural yeast nutrient (fermented Parkia biglobosa seeds) on bioethanol production from cashew apple juice by Saccharomyces cerevisiae. The proximate and mineral compositions of fermented seeds were evaluated. Their powder was added to yeast medium at a concentration of 4–12 g/L. The behavior of two yeast strains (Angel brand super alcohol (S1) and Angel brand thermal-tolerant alcohol (S2)) was inspected. Titratable acidity, pH, °Brix, and density were evaluated during 144 h of fermentation. Sugar consumption was maximal after 72 and 48 h of fermentation for S1 and S2 yeast strains, respectively. The best ethanol yields of 0.19 and 0.22 g/g were obtained with S1 and S2 yeast strains, respectively, using 12 g/L of nutrients for the first and without nutrient supplementation for the second (control sample). The non-conventional nutrients from fermented P. biglobosa seeds seem to be favorablefor ethanol production using only S1 yeast strain.
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Nedyalkov, Petar, Maria Kaneva, Vesela Shopska, Rositsa Denkova, Georgi Kostov, Zapryana Denkova, Desislava Teneva y Bogdan Goranov. "Yeast selection for non-alcoholic and low-alcoholic beverages based on wort". Food Science and Applied Biotechnology 2, n.º 2 (10 de octubre de 2019): 140. http://dx.doi.org/10.30721/fsab2019.v2.i2.61.
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A series of wort fermentations with eight yeast strains were carried out in laboratory conditions. The strains used were: Saccharomyces cerevisiae (2 strains), Saccharomyces diastaticus (3 strains), Saccharomyces carlsbergensis (1 strain), Saccharomyces lactis (1 strain), Saccharomyces sake gekkeikan (1 strain). Selection of yeast strains has been performed in order to study the possibilities for their aplication to obtain fermentable non-alcoholic and low-alcoholic beverages based on wort. Three yeast strains (two of Saccharomyces cerevisiae and one Saccharomyces diastaticus), were selected based on their good growth in the used medium and the pleasant organoleptic profile formed as a result of the fermentation carried out. The accumulated alcohol values varied between 0.05 and 0.22 % (w/w).
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Nagy, Edina, Marete Niss, Dénes Dlauchy, Nils Arneborg, Dennis Sandris Nielsen y Gábor Péter. "Yarrowia divulgata f.a., sp. nov., a yeast species from animal-related and marine sources". International Journal of Systematic and Evolutionary Microbiology 63, Pt_12 (1 de diciembre de 2013): 4818–23. http://dx.doi.org/10.1099/ijs.0.057208-0.
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Five yeast strains, phenotypically indistinguishable from Yarrowia lipolytica and Yarrowia deformans, were recovered from different animal-related samples. One strain was isolated from a bacon processing plant in Denmark, two strains from chicken liver in the USA, one strain from chicken breast in Hungary and one from minced beef in Hungary. Comparisons of the sequences of their large subunit rRNA gene D1/D2 domain and the internal transcribed spacer (ITS) regions revealed that, despite their phenotypic similarity, they represent a novel yeast species of the Yarrowia clade with Y. deformans being the genotypically closest relative (LSU rRNA gene D1/D2 and ITS region similarity of 97.0 and 93.7 %, respectively). Yarrowia divulgata f.a., sp. nov. is proposed to accommodate these strains with F6-17T ( = CBS 11013T = CCUG 56725T) as the type strain. Some D1/D2 sequences of yeasts from marine habitats were found in the GenBank database that were identical to those of the strains of Y. divulgata f.a., sp. nov. Unfortunately, these strains were not available for our study.
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Vadkertiová, Renáta y Elena Sláviková. "Killer activity of yeasts isolated from the water environment". Canadian Journal of Microbiology 41, n.º 9 (1 de septiembre de 1995): 759–66. http://dx.doi.org/10.1139/m95-105.
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The killer activity of 46 strains belonging to 12 yeast and yeast-like species isolated from water or sediment samples was studied. Only two strains of the genus Cryptococcus did not show killer activity. Killer activity of yeast-like species Aureobasidium pullulans, Hyphopichia burtonii and Geotrichum candidum, and yeast species Candida krusei and Candida lambica was low. Sporobolomyces salmonicolor, Cryptococcus laurentii and Cryptococcus albidus had better activity against basidiomycetous than ascomycetous species. Hansenula anomala strains showed good activity against Geotrichum candidum strains, Cryptococcus albidus, and Sporobolomyces salmonicolor. Rhodotorula species showed activity against the majority of both ascomycetous and basidiomycetous species.Key words: yeasts, killer activity, sediment and water samples.
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Zhou, Nerve, Thandiwe Semumu y Amparo Gamero. "Non-Conventional Yeasts as Alternatives in Modern Baking for Improved Performance and Aroma Enhancement". Fermentation 7, n.º 3 (27 de junio de 2021): 102. http://dx.doi.org/10.3390/fermentation7030102.
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Saccharomyces cerevisiae remains the baker’s yeast of choice in the baking industry. However, its ability to ferment cereal flour sugars and accumulate CO2 as a principal role of yeast in baking is not as unique as previously thought decades ago. The widely conserved fermentative lifestyle among the Saccharomycotina has increased our interest in the search for non-conventional yeast strains to either augment conventional baker’s yeast or develop robust strains to cater for the now diverse consumer-driven markets. A decade of research on alternative baker’s yeasts has shown that non-conventional yeasts are increasingly becoming important due to their wide carbon fermentation ranges, their novel aromatic flavour generation, and their robust stress tolerance. This review presents the credentials of non-conventional yeasts as attractive yeasts for modern baking. The evolution of the fermentative trait and tolerance to baking-associated stresses as two important attributes of baker’s yeast are discussed besides their contribution to aroma enhancement. The review further discusses the approaches to obtain new strains suitable for baking applications.
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Liu, Tian Ming, Hui Hui Wang, Ke Wang, Hui Wang, Xiu Bao Zhao y Yu Qi Tang. "Enology Characteristics of Yeasts Saccharomyces cerevisiae and Hanseniaspora uvarum Selected for Chinese Original Wine". Advanced Materials Research 365 (octubre de 2011): 233–39. http://dx.doi.org/10.4028/www.scientific.net/amr.365.233.
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The enology characteristics were studied by three yeast strains of pure and mixed cultures of Saccharomyces cerevisiae QM, ZYFJQ and Hanseniaspora uvarum YQY with Cabernet sauvignon grape,respectively, while the commercial Saccharomyces cerevisiae RC212 was made as a control, in order to screen excellent yeast strains or the combination of those for the original wine. Chemical indices of the wines by three stiains were analyzed including ethanol, total acidity, volatile acidity and residual reducing sugar. Flavor compounds in wines and in must were extracted by dichloromethane and identified by GC–MS.The results showed that the chemical indices of the wine from selected strains could satisfy with the demand of Chinese national standard, and the volatiles were mainly the 2-phenylethanol, which shaped the main characteristics of wine aroma components. yeast strain QM and YQY got the best balance between acetate and alcohols. The best volatiles of wine was obtained from the mixed fermentations than from the pure or from the control ones. ndigenous yeast strains from grape played an important role on the types and amounts of flavor compounds in mixed culture fermentation. The yeasts could have potential applications to the original winemaking.
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VEGAS, CARLOS, AMPARO I. ZAVALETA, PAMELA E. CANALES y BRAULIO ESTEVE-ZARZOSO. "Yeasts Associated with Various Amazonian Native Fruits". Polish Journal of Microbiology 69, n.º 3 (5 de agosto de 2020): 251–61. http://dx.doi.org/10.33073/pjm-2020-027.
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Yeasts, commonly present on the surface of fruits, are of industrial interest for the production of enzymes, flavorings, and bioactive compounds, and have many other scientific uses. The Amazonian rainforest may be a good source of new species or strains of yeasts, but their presence on Amazonian fruits is unknown. The aim of this study was to identify and characterize yeasts isolated from Amazonian native fruits using molecular and phenotypic methods. In total, 81 yeast isolates were obtained from 10 fruits species. Rep-PCR showed 29 strain profiles. Using a combination of restriction-fragment length polymorphism (RFLP) of the 5.8S-ITS region and D1/D2 sequencing of the 26S rRNA gene, 16 species were identified belonging to genera Candida, Debaryomyces, Hanseniaspora, Kodamaea, Martiniozyma, and Meyerozyma. The most dominant species were Candida tropicalis, Debaryomyces hansenii, Hanseniaspora opuntiae, and Hanseniaspora thailandica. H. opuntiae and H. thailandica showed the highest number of the strain profiles. Phenotypic profiles were variable between species, and even among strains. Screening for hydrolases showed lipolytic activity in only one isolate, while proteolytic, cellulolytic and amylolytic capabilities were not detected. Yeast presence among fruits varied, with cidra (Citrus medica) and ungurahui (Oenocarpus bataua) having the highest number of species associated. This investigation broadens the understanding and possible biotechnological uses of yeast strains obtained from Amazonian native fruits.
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Kumla, Jaturong, Supakorn Nundaeng, Nakarin Suwannarach y Saisamorn Lumyong. "Evaluation of Multifarious Plant Growth Promoting Trials of Yeast Isolated from the Soil of Assam Tea (Camellia sinensis var. assamica) Plantations in Northern Thailand". Microorganisms 8, n.º 8 (1 de agosto de 2020): 1168. http://dx.doi.org/10.3390/microorganisms8081168.
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Some soil microorganisms, especially bacteria and mycorrhizal fungi, play a role in the promotion of plant growth. However, plant growth promotion involving yeasts in soil has not yet been extensively investigated. This study aimed to isolate and identify yeast strains obtained from soils of the Assam tea plant (Camellia sinensis var. assamica) in northern Thailand and to investigate their plant growth promoting capabilities. A total of 42 yeast strains were obtained and identified by analysis of the D1/D2 domain of the large subunit ribosomal RNA gene. We identified 35 strains of six species belonging to the phylum Ascomycota, namely Aureobasidium melanogenum, Kazachstania aquatica, Saturnispora diversa, Saturnispora sekii, Schwanniomyces pseudopolymorphus and Wickerhamomyces anomalus, and six species were determined to belong to the phylum Basidiomycota, namely Apiotrichum scarabaeorum, Curvibasidium pallidicorallinum, Papiliotrema laurentii, Rhodosporidiobolus ruineniae, Trichosporon asahii and Trichosporon coremiiforme. Seven strains were representative of potential new species and belonged to the genera Galactomyces and Wickerhamomyces. A total of 28 strains were found to produce indole-3-acetic acid (IAA) in a range of 2.12 to 37.32 mg/L, with the highest amount of IAA produced by R. ruineniae SDBR-CMU-S1-03. All yeast strains were positive in terms of ammonia production, and only eight strains were positive for siderophore production. Two yeast species, P. laurentii and W. anomalus, were able to solubilize the insoluble form of calcium and zinc. The ability to produce amylase, endogulcanase, lipase, pectinase, protease and xylanase was dependent upon the yeast species and strain involved.
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Chreptowicz, Karolina, Jolanta Mierzejewska, Jana Tkáčová, Mateusz Młynek y Milan Čertik. "Carotenoid-Producing Yeasts: Identification and Characteristics of Environmental Isolates with a Valuable Extracellular Enzymatic Activity". Microorganisms 7, n.º 12 (4 de diciembre de 2019): 653. http://dx.doi.org/10.3390/microorganisms7120653.
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Sixteen cold-adapted reddish-pigmented yeast strains were obtained from environmental samples. According to the PCR-based detection of classical yeast markers combined with phylogenetic studies, the yeasts belong mainly to the genera Rhodotorula, Sporobolomyces and Cystobasidium, all within the subphylum Pucciniomycotina. All strains produced carotenoids within a 0.25–10.33 mg/L range under non-optimized conditions. Noteworthily, among them, representatives of the Cystobasidium genus were found; of particular value are the strains C. laryngis and C. psychroaquaticum, poorly described in the literature to date. Interestingly, carotenoid production with representatives of Cystobasidium was improved 1.8- to 10-fold at reduced temperature. As expected, most of the isolated yeasts biosynthesized extracellular lipases, but within them also one proteolytic and four cellulolytic strains were revealed. We succeeded in isolating strain Cystofilobasidium macerans WUT145 with extraordinarily high cellulolytic activity at 22°C (66.23 ± 0.15 µmol/mg protein·min) that is described here for the first time. Consequently, a set of yeasts capable of producing both carotenoids and extracellular enzymes was identified. Taking into account those abilities, the strains might be applicable for a development of carotenoids production on an agro-industrial waste, e.g., lignocellulose.
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Tian, Bai-Chuan, Guang-Lei Liu, Zhe Chi, Zhong Hu y Zhen-Ming Chi. "Occurrence and Distribution of Strains of Saccharomyces cerevisiae in China Seas". Journal of Marine Science and Engineering 9, n.º 6 (29 de mayo de 2021): 590. http://dx.doi.org/10.3390/jmse9060590.
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The yeast Saccharomyces cerevisiae has been widely applied in fermentation industries, chemical industries and biological research and it is widespread in different environments, especially in sugar-rich environments. However, little is known about the occurrence, distribution and roles of S. cerevisiae in marine environments. In this study, only 10 strains among all the yeasts isolated from different marine environments belonged to S. cerevisiae. It was found that most of the strains of S. cerevisiae in marine environments occurred in guts, the surface of marine fish and mangrove trees. In contrast, they were not found in seawater and sediments. All the strains of S. cerevisiae isolated from the marine environments had a lower ability to produce ethanol than the highly alcohol-producing yeast Saccharomyces sp. W0 isolated from fermented rice, but the strains 2E00400, 2E00558, 2E00498, 2E00723, 2E00724 could produce higher concentrations of ethanol than any other marine-derived strains of S. cerevisiae obtained in this study. However, some of them had higher ethanol tolerance and higher trehalose content than Saccharomyces sp. W0. In particular, ethanol tolerance of the yeast strain 2E00498 was higher than that of Saccharomyces sp. W0. This may be related to the harsh marine environments from which they were isolated. Such yeast strains with higher alcohol tolerance could be used to further improve the alcohol tolerance of Saccharomyces sp. W0.