Qualitative and quantitative screening of the β -glucosidase activity in Saccharomyces cerevisiae and Saccharomyces uvarum strains isolated from refrigerated must

Application of Immobilized β-Glucosidase from Candida boidinii in the Hydrolysis of Delignified Sugarcane Bagasse

Candida boidinii is a methylotrophic yeast with wide geographical distribution. In the present study, the microorganism was isolated from the Bahian semiarid and the enzymatic extract containing β-glucosidase was obtained through submerged fermentation. Response surface methodology was employed to optimize of fermentation medium. The higher production of β-glucosidase was obtained after 71 h of fermentation in an optimized medium composed of 3.35% glucose, 1.78% yeast extract and 1% peptone. The optimum pH and temperature of enzymatic activity were 6.8 (citrate-phosphate buffer) and 71.7 °C, respectively. Salts tested (10 mM) CaCl2, Na2SO4 and ZnSO4 promotes the increase of 91%, 45% and 80% of activity, respectively. The enzyme retained 64% ± 2.3 of its initial activity after 1 h heating at 90 °C. The production of reducing sugars was 95.94% after 24 h of hydrolysis and, with the addition of metal ions, this value increased more than 2 times. Among the supports analyzed for immobilization, chitosan showed higher residual activity during reuse. The immobilized enzyme showed higher activity at 60 °C with pH 6 and preserved almost 100% of the initial activity after 30 min at 70 °C.

Biochemical Composition, Antioxidant Capacity and Protective Effects of Three Fermented Plants Beverages on Hepatotoxicity and Nephrotoxicity Induced by Carbon Tetrachloride in Mice

Functional beverages play an essential role in our modern life and contribute to nutritional well-being. Current efforts to understand and develop functional beverages to promote health and wellness have been enhanced. The present study aimed to investigate the production of three fermented plants beverages (FPBs) from aromatic and medicinal plants and to evaluate the fermented product in terms of physio-biochemical composition, the aromatic compounds, antioxidant activity, and in vivo protective effects on hepatotoxicity and nephrotoxicity induced by carbon tetrachloride (CCl4). The results showed that the fermented beverage NurtBio B had the highest levels of polyphenols, flavonoids, and tannins; 242.3 ± 12.4 µg GAE/mL, 106.4 ± 7.3 µg RE/mL and 94.2 ± 5.1 µg CE/mL, respectively. The aromatic profiles of the fermented beverages showed thirty-one interesting volatile compounds detected by GC-MS headspace analyses such as benzaldehyde, Eucalyptol, Fenchone, 3-Octadecyne, Estragole, and Benzene propanoic acid 1-methylethyl ester. In addition, the fermentation process was significantly improved, indicating its great potential as a functional food with both strong antioxidant activity and good flavor. In vivo administration of CCl4 in mice induced hepatotoxicity and nephrotoxicity by a significant rise in the levels of serum liver and kidney biomarkers. The protective effects of the FPBs showed that they significantly restored the majority of these biological parameters to normal levels, along with increase antioxidant enzyme activities, as well as an improvement of histopathological changes, suggesting their protective effects.

Microbial production and applications of β-glucosidase-A review

β-Glucosidase exists in all areas of living organisms, and microbial β-glucosidase has become the main source of its production because of its unique physicochemical properties and the advantages of high-yield production by fermentation. With the rise of the green circular economy, the production of enzymes through the fermentation of waste as the substrate has become a popular trend. Lignocellulosic biomass is an easily accessible and sustainable feedstock that exists in nature, and the production of biofuels from lignocellulosic biomass requires the involvement of β-glucosidase. This review proposes ways to improve β-glucosidase yield and catalytic efficiency. Optimization of growth conditions and purification strategies of enzymes can increase enzyme yield, and enzyme immobilization, genetic engineering, protein engineering, and whole-cell catalysis provide solutions to enhance the catalytic efficiency and activity of β-glucosidase. Besides, the diversified industrial applications, challenges and prospects of β-glucosidase are also described.

Quinoa dough fermentation by Saccharomyces cerevisiae and lactic acid bacteria: Changes in saponin, phytic acid content, and antioxidant capacity

The effects of two fermentation processes (common fermentation with Saccharomyces cerevisiae and fermentation by Lacticaseibacillus casei subsp. casei PTCC 1608 and Lactiplantibacillus plantarum subsp. plantarum PTCC 1745) on pH, titratable acidity, total phenolic and flavonoid contents, antioxidant capacity, saponin content, as well as phytic acid content of quinoa dough were investigated during the 24-h fermentation (4-h interval). According to the results, the highest titratable acidity was observed in the samples fermented by L. casei subsp. casei. Moreover, the highest antioxidant capacity was observed after 12 h of fermentation by L. plantarum subsp. plantarum (31.22% for DPPH, 104.67% for FRAP) due to a higher concentration of phenolic compounds produced (170.5% for total phenolic content). Also, all samples have been able to reduce saponin by 67% on average. Furthermore, the samples fermented by L. plantarum subsp. plantarum showed the most significant decrease in phytic acid content (64.64%) during 24-h fermentation. By considering the reduction of the antinutritional compounds and improvement in the antioxidant properties of quinoa flour, the Lactiplantibacillus plantarum strain was recommended.

Evaluation of Indigenous Yeasts Screened from Chinese Vineyards as Potential Starters for Improving Wine Aroma

Exploitation of the biodiversity of native wine yeast is a means of modifying the sensory characteristics of wine. Samples from different regions in China were analysed to screen native isolates as potential starter cultures. Through morphological and molecular biological analyses, we found six species, belonging to four genera (Hanseniaspora, Saccharomyces, Rhodotorula and Metschnikowia). These species were subjected to stress tolerance assays (ethanol, glucose, SO2 and pH), enzymatic activity tests (sulphite reductase activity, β-glucosidase activity and protease activity) and fermentation tests. Saccharomyces cerevisiae showed a high tolerance to ethanol and completed fermentation independently. Hanseniaspora demonstrated good enzymatic activity and completed sequential fermentation. The fermentation experiment showed that the PCT4 strain had the best aroma complexity. This study provides a reference for selecting new starters from the perspective of flavour enzymes and tolerance and diversifying the sensory quality of wines from the region.

Biotransformations Performed by Yeasts on Aromatic Compounds Provided by Hop—A Review

The biodiversity of some Saccharomyces (S.) strains for fermentative activity and metabolic capacities is an important research area in brewing technology. Yeast metabolism can render simple beers very elaborate. In this review, we examine much research addressed to the study of how different yeast strains can influence aroma by chemically interacting with specific aromatic compounds (mainly terpenes) from the hop. These reactions are commonly referred to as biotransformations. Exploiting biotransformations to increase the product’s aroma and use less hop goes exactly in the direction of higher sustainability of the brewing process, as the hop generally represents the highest part of the raw materials cost, and its reduction allows to diminish its environmental impact.

Screening for cellulases and preliminary optimisation of glucose tolerant β-glucosidase production and characterisation

The search for a novel microbial producer of cellulases including a glucose tolerant β-glucosidase is a challenge as most are inhibited by their product glucose. This study aims to screen for cellulolytic fungi using qualitative and quantitative screening methods. Primary screening revealed 34 of 46 fungal isolates with β-glucosidase activity. Eleven and 13 of these also displayed endoglucanase and exoglucanase activities, respectively. During secondary screening, this number was reduced to 26 β-glucosidase producers with 13 also having endoglucanase and exoglucanase activities. Isolate C1 displayed enhanced production of β-glucosidases in the presence of 0.05 M glucose (69% higher activity). Optimisation of growth conditions for β-glucosidase production by one variable at a time experiments improved production for (isolates) PS1 (64%), MB5 (84%), and C2 (69%). Isolate PS1 identified as Chaetomella sp. BBA70074 displayed the highest tolerance to glucose, retaining 10% of β-glucosidase activity in the presence of 0.8 M glucose. Tolerance to glucose increased to 14% when produced under optimal conditions. β-Glucosidase had a molecular weight of 170 kDa with a pH and temperature optima of 6 and 70°C, respectively. Future studies will include optimisation of the production of the glucose tolerant enzyme by Chaetomella sp. BBA70074.

Torulaspora delbrueckii Phenotypic and Metabolic Profiling towards Its Biotechnological Exploitation

Wine is a particularly complex beverage resulting from the combination of several factors, with yeasts being highlighted due to their fundamental role in its development. For many years, non-Saccharomyces yeasts were believed to be sources of spoilage and contamination, but this idea was challenged, and many of these yeasts are starting to be explored for their beneficial input to wine character. Among this group, Torulaspora delbrueckii is gaining relevance within the wine industry, owing to its low volatile acidity production, increased release of aromatic compounds and enhanced color intensity. In addition, this yeast was also attracting interest in other biotechnological areas, such as bread and beer fermentation. In this work, a set of 40 T. delbrueckii strains, of varied geographical and technological origins, was gathered in order to characterize the phenotypic behavior of this species, focusing on different parameters of biotechnological interest. The fermentative performance of the strains was also evaluated through individual fermentations in synthetic grape must with the isolates’ metabolic profile being assessed by HPLC. Data analysis revealed that T. delbrueckii growth is significantly affected by high temperature (37 °C) and ethanol concentrations (up to 18%), alongside 1.5 mM SO₂, showing variable fermentative power and yields. Our computation models suggest that the technological origin of the strains seems to prevail over the geographical origin as regards the influence on yeast properties. The inter-strain variability and profile of the products through the fermentative processes reinforce the potential of T. delbrueckii from a biotechnological point of view.

Microbial dynamics in industrial-scale wine fermentation employing Hanseniaspora uvarum β-glucosidase-producer strain

The use of non-Saccharomyces yeast strains in winemaking is becoming a common trend. In fact, consumers are demanding new and healthier styles of wine. On the other hand, these strains are a challenge for the starting process due to winery-resident strains, especially with regard to industrial-scale fermentations. Current assay focuses on the scale-up of the laboratorial inoculum inside the winery environment to ferment 15,000 and 25,000 L of Vitis labrusca Bordô must, using a Hanseniaspora uvarum β-glucosidase-producer strain as starter culture. This scale-up could confirm the viability of using non-Saccharomyces yeast, as it presented promising results on a laboratory scale. The non-Saccharomyces strain was selected in a previous study since it proved to increase resveratrol concentration in lab scale winemaking. The yeast diversity was followed by the plate culturing method. Species identification and strain typing were determined by ITS-RFLP and PCR-fingerprinting, respectively. Physical and chemical analyses and resveratrol quantification were performed in the elaborated wines.

Functional properties and potential application of ethanol tolerant β-glucosidases from Pichia ofunaensis and Trichosporon multisporum yeasts

β-Glucosidases have been extensively investigated to integrate the enzyme complex for cellulose fiber saccharification and for improving the aroma of wine. To produce these enzymes, greater attention has been given to filamentous fungi and bacteria, and few investigations have targeted the potential applications of enzymes secreted by yeasts. Addressing this issue, in this study, β-glucosidases were produced by the Pichia ofunaensis and Trichosporon multisporum yeasts, via solid state fermentation with wheat bran as a substrate. When using p-Nitrophenyl β-d-glucopyranoside (pNPG) as an enzyme substrate, maximum β-glucosidase activities were detected at pH 5.5-6.0 and 50-60 °C for P. ofunaensis, and pH 5-6 and 55 °C for T. multisporum. Both enzymes were able to hydrolyze cellobiose and exhibited stability over a wide range of pH (3.5-9.0) for 24 h at 4 °C, thermostability up to 50 °C for 1 h and tolerance to 10 mM phenolic compounds. Negative modulation on enzyme activity was observed in the presence of Cu2+, Fe3+, Zn2+, Al3+ and Hg2+, while both β-glucosidases were tolerant to 30% methanol, isopropanol and acetone. In the presence of ethanol and glucose, enzymes from P. ofunaensis were the more active and stable of the two. These enzymes, especially the P. ofunaensis β-glucosidases, could be tested in enology for improving the aroma of wine and for integrating a cellulolytic complex to produce 2G ethanol.

Beta-glucosidase activity of wine yeasts and its impacts on wine volatiles and phenolics: A mini-review

Beta-glucosidase is an important enzyme for the hydrolysis of grape glycosides in the course of winemaking. Yeasts are the main producers of β-glucosidase in winemaking, therefore play an important role in determining wine aroma and flavour. This article discusses common methods for β-glucosidase evaluation, the β-glucosidase activity of different Saccharomyces and non- Saccharomyces yeasts and the influences of winemaking conditions, such as glucose and ethanol concentration, low pH environment, fermentation temperature and SO₂ level, on their activity. This review further highlights the roles of β-glucosidase in promoting the release of free volatile compounds especially terpenes and the modification of wine phenolic composition during the winemaking process. Furthermore, this review proposes future research direction in this area and guides wine professionals in yeast selection to improve wine quality.

Design of a New Fermented Beverage from Medicinal Plants and Organic Sugarcane Molasses via Lactic Fermentation

Functional beverages obtained using medicinal plants and fermented with lactic acid bacteria are gaining much interest from the scientific community, driven by the growing demand for food and beverages with beneficial properties. In this work, three different batches of medicinal plants and organic sugarcane molasses, named FB-lc, FB-sp and FB-lcsp, were prepared and fermented by using Lactobacillus acidophilus ATCC 43121, Bifidobacterium breve B632 and a mix of both strains’ culture, respectively. The three fermented beverages revealed a high level of polyphenols (expressed as gallic acid equivalent), ranging from 182.50 to 315.62 µg/mL. The highest content of flavonoids (152.13 µg quercetin equivalent/mL) and tannins (93.602 µg catechin equivalent/mL) was detected in FB-lcsp trial. The IR spectroscopy analysis showed a decrease in sugar (pyranose forms, D-glucopyranose and rhamnosides). In addition, the aromatic compounds of the fermented beverages, detected by GC-MS headspace analysis, showed twenty-four interesting volatile compounds, which could give positive aroma attributes to the flavor of the beverages. The highest antioxidant activity was observed in the beverage obtained by the mix culture strains. Accordingly, the production of these beverages can be further investigated for considering their well-being effects on human health.

Wine phenolic profile altered by yeast: Mechanisms and influences

Grape phenolic compounds undergo various types of transformations during winemaking under the influences of yeasts, which further impacts the sensory attributes, thus the quality of wine. Understanding the roles of yeasts in phenolics transformation is important for controlling wine quality through fermentation culture selection. This literature review discusses the mechanisms of how yeasts alter the phenolic compounds during winemaking, summarizes the effects of Saccharomyces cerevisiae and non-Saccharomyces yeasts on the content and composition of phenolics in wine, and highlights the influences of mixed cultural fermentation on the phenolic profile of wine. Collectively, this paper aims to provide a deeper understanding on yeast-phenolics interactions and to identify the current literature gaps for future research.

Yeast Biodiversity in Fermented Doughs and Raw Cereal Matrices and the Study of Technological Traits of Selected Strains Isolated in Spain

Bakers use pure microorganisms and/or traditional sourdoughs as the leavening agent for making bread. The performance of each starter and the substances produced by the microorganisms greatly affect the dough rheology and features of breads. Modern sourdoughs inoculated with selected lactic acid bacteria and yeasts are microbiologically stable, safer than traditional sourdoughs, and easy to use. However, the commercial repertoire of baker’s yeasts is still limited. Therefore, there is a demand for new strains of yeast species, capable of conferring distinctive traits to breads made from a variety of agri-food matrices, in the design of innovative starters. In this context, we report the first comprehensive study on yeasts isolated from a wide range of fermented doughs, cereal flours, and grains of Spain. Nine yeast species were identified from 433 isolates, which were distributed among separate clades. Moreover, phenotypic traits of potential technological relevance were identified in selected yeast strains. Mother doughs (MDs) showed the greatest yeast biodiversity, whereas commercial Saccharomyces starters or related and wild strains often dominated the bakery doughs. A metataxonomic analysis of wheat and tritordeum MDs revealed a greater richness of yeast species and percentage variations related to the consistency, flour type, and fermentation time of MDs.

Screening and characterisation of β-glucosidase production strains from Rosa roxburghii Tratt

The β-glucosidase properties from one yeast isolate identified as Wickerhamomyces anomalus C4 were characterised. The β-glucosidase activity of W. anomalus C4 was 41.83 ± 0.25 mU/mL, and the optimum temperature and pH were 40 °C and 5.0, respectively. The glucose, 10% v/v of ethanol and 10 mmol/L of Cu2+ inhibited the β-glycosidases activities. The isolate W. anomalus C4 had a stronger alcohol metabolism capacity than commercial Saccharomyces cerevisiae X16. Besides, fermentation with W. anomalus C4 alone and co-fermentations with S. cerevisiae X16 and W. anomalus C4 reduced the volatile acids content and the sourness value compared to S. cerevisiae X16 control. Moreover, inoculation with W. anomalus C4 could enhance volatile aroma richness and complexity of Rosa roxburghii wines, regardless of type or amount thereof. Therefore, the R. roxburghii native yeast isolate W. anomalus C4 may have some application potentials for R. roxburghii wine-making.

Selection of Wine Saccharomyces cerevisiae Strains and Their Screening for the Adsorption Activity of Pigments, Phenolics and Ochratoxin A

Ochratoxin A is a dangerous mycotoxin present in wines and is considered the principal safety hazard in the winemaking process. Several authors have investigated the ochratoxin A adsorption ability of Saccharomyces cerevisiae yeasts, and specifically selected strains for this desired trait. In the present work, a huge selection of wine yeasts was done starting from Portuguese, Spanish and Italian fermenting musts of different cultivars. Firstly, 150 isolates were collected, and 99 non-redundant S. cerevisiae strains were identified. Then, the strains were screened following a multi-step approach in order to select those having primary oenological traits, mainly (a) good fermentation performance, (b) low production of H2S and (c) low production of acetic acid. The preselected strains were further investigated for their adsorption activity of pigments, phenolic compounds and ochratoxin A. Finally, 10 strains showed the desired features. The goal of this work was to select the strains capable of absorbing ochratoxin A but not pigments and phenolic compounds in order to improve and valorise both the quality and safety of red wines. The selected strains are considered good candidates for wine starters, moreover, they can be exploited to obtain a further enhancement of the specific adsorption/non-adsorption activity by applying a yeast breeding approach.