Microbial interactions in alcoholic beverages

Influence of an indigenous yeast, CECA, from the Ningxia wine region of China, on the fungal and bacterial dynamics and function during Cabernet Sauvignon wine fermentation

BACKGROUND

Saccharomyces cerevisiae CECA was a potential indigenous Chinese wine yeast that can produce aroma and flavor in Cabernet Sauvignon wines. High-throughput sequencing combined with metabolite analysis was applied to analyze the effects of CECA inoculation on the native microbial community interaction and metabolism during Cabernet Sauvignon wine fermentation.

RESULTS

Fermentations were performed with three different inoculant strategies: spontaneous fermentation without inoculation, inoculation with CECA after grape must sterilization, and direct inoculation of CECA. Results showed that the diversity of bacteria (P = 0.033) is more sensitive to CECA inoculation than fungi (P = 0.563). In addition, CECA inoculation altered the species composition of core microorganisms (relative abundance >1%) and the keystone species (accounting for the top 1% of the most important interactions), as well as of the biomarkers (linear discriminant analysis > 3.0, P < 0.05). Furthermore, the inoculation could change the cluster of metabolites, and these differential metabolite sets were correlated with four fungal taxa of Issatchenkia, Issatchenkia orientalis, Saccharomycetales, Saccharomycetes and two bacterial taxa of Pantoea, Tatumella ptyseos, were significantly correlated. Inoculated fermentation also altered the correlation between dominant microorganisms and aroma compounds, giving Cabernet Sauvignon wines more herbal, floral, fruity, and cheesy aromas.

CONCLUSION

Saccharomyces cerevisiae CECA and dimethyl dicarbonate (DMDC) inhibition treatments significantly altered the microbial community structure of Cabernet Sauvignon wines, which in turn affected the microbial-metabolite correlation. These findings will help winemakers to control the microbial dynamics and functions during wine fermentation, and be more widely used in regional typical wine fermentations. © 2024 Society of Chemical Industry.

Comparing Nutritional Values and Bioactivity of Kefir from Different Types of Animal Milk

The growing interest in fermented dairy products is due to their health-promoting properties. The use of milk kefir grains as a starter culture made it possible to obtain a product with a better nutritional and biological profile depending on the type of milk. Cow, buffalo, camel, donkey, goat, and sheep milk kefirs were prepared, and the changes in sugar, protein, and phenol content, fatty acid composition, including conjugated linoleic acids (CLAs), as well as antioxidant activity, determined by ABTS and FRAP assays, were evaluated and compared. The protein content of cow, buffalo, donkey, and sheep milk increased after 24 h of fermentation. The fatty acid profile showed a better concentration of saturated and unsaturated lipids in all fermented milks, except buffalo milk. The highest content of beneficial fatty acids, such as oleic, linoleic, and C18:2 conjugated linoleic acid, was found in the cow and sheep samples. All samples showed a better antioxidant capacity, goat milk having the highest value, with no correlation to the total phenolic content, which was highest in the buffalo sample (260.40 ± 5.50 μg GAE/mL). These findings suggested that microorganisms living symbiotically in kefir grains utilize nutrients from different types of milk with varying efficiency.

Identification of keystone taxa in rhizosphere microbial communities using different methods and their effects on compounds of the host Cinnamomum migao

Exploring keystone taxa affecting microbial community stability and host function is crucial for understanding ecosystem functions. However, identifying keystone taxa from humongous microbial communities remains challenging. We collected 344 rhizosphere and bulk soil samples from the endangered plant C. migao for 2 years consecutively. Used high-throughput sequencing 16S rDNA and ITS to obtain the composition of bacterial and fungal communities. We explored keystone taxa and the applicability and limitations of five methods (SPEC-OCCU, Zi-Pi, Subnetwork, Betweenness, and Module), as well as the impact of microbial community domain, time series, and rhizosphere boundary on the identification of keystone taxa in the communities. Our results showed that the five methods, identified abundant keystone taxa in rhizosphere and bulk soil microbial communities. However, the keystone taxa shared by the rhizosphere and bulk soil microbial communities over time decreased rapidly decrease in the five methods. Among five methods on the identification of keystone taxa in the rhizosphere community, Module identified 113 taxa, SPEC-OCCU identified 17 taxa, Betweenness identified 3 taxa, Subnetwork identified 3 taxa, and Zi-Pi identified 4 taxa. The keystone taxa are mainly conditionally rare taxa, and their ecological functions include chemoheterotrophy, aerobic chemoheterotrophy, nitrate reduction, and anaerobic photoautotrophy. The results of the random forest model and structural equation model predict that keystone taxa Mortierella and Ellin6513 may have an effects on the accumulation of 1, 4, 7, - Cycloundecatriene, 1, 5, 9, 9-tetramethyl-, Z, Z, Z-, beta-copaene, bicyclogermacrene, 1,8-Cineole in C. migao fruits, but their effects still need further evidence. Our study evidence an unstable microbial community in the bulk soil, and the definition of microbial boundary and ecologically functional affected the identification of keystone taxa in the community. Subnetwork and Module are more in line with the definition of keystone taxa in microbial ecosystems in terms of maintaining community stability and hosting function.

Protective Mechanism of Eurotium amstelodami from Fuzhuan Brick Tea against Colitis and Gut-Derived Liver Injury Induced by Dextran Sulfate Sodium in C57BL/6 Mice

The study explored the potential protective impact of the probiotic fungus Eurotium amstelodami in Fuzhuan brick tea on ulcerative colitis, along with the underlying mechanism. A spore suspension of E. amstelodami was administered to C57BL/6 mice to alleviate DSS-induced colitis. The findings indicated that administering E. amstelodami evidently enhanced the ultrastructure of colonic epithelium, showing characteristics such as enhanced TJ length, reduced microvilli damage, and enlarged intercellular space. After HLL supplementation, the activation of the liver inflammation pathway, including TLR4/NF-kB and NLRP3 inflammasome caused by DSS, was significantly suppressed, and bile acid metabolism, linking liver and gut, was enhanced, manifested by restoration of bile acid receptor (FXR, TGR5) level. The dysbiosis of the gut microbes in colitis mice was also restored by HLL intervention, characterized by the enrichment of beneficial bacteria (Lactobacillus, Bifidobacterium, Akkermansia, and Faecalibaculum) and fungi (Aspergillus, Trichoderma, Wallemia, Eurotium, and Cladosporium), which was closely associated with lipid metabolism and amino acid metabolism, and was negatively correlated with inflammatory gene expression. Hence, the recovery of gut microbial community structure, implicated deeply in the inflammatory index and metabolites profile, might play a crucial role in the therapeutic mechanism of HLL on colitis.

Insights into characteristic metabolites and potential bioactive peptides profiles of fresh cheese fermented with three novel probiotics based metabolomics and peptidomics

The metabolite and peptide profiles of fresh cheese fermented by three novel probiotics, Lacticaseibacillus rhamnosus B6, Limosylactobacillus fermentum B44 and Lacticaseibacillus rhamnosus KF7, were investigated using LC-MS/MS-based metabolomics and peptidomics. The multivariate analysis revealed significant differences in metabolite composition between the probiotic fresh cheese and the control sample. The differential metabolites were primarily lipids and lipid-like molecules and organic oxygen compounds, which were associated with fatty acid and carbohydrate-related pathways. Among three probiotics, L. rhamnosus KF7 showed the highest effectiveness in sucrose decomposition. 147 potential bioactive peptides, mainly derived from casein, were identified in probiotic fresh cheese. Furthermore, 112 bioactive peptides were significantly up-regulated in probiotic fresh cheese. Molecular docking analysis indicated that two short peptides (LVYPFPGPIP and YPQRDMPIQ) in the B44 and KF7 groups exhibited low estimated binding energy values (-9.9 and -6.9 kcal/mol) with ACE. These findings provide a theoretical basis for developing novel probiotic-enriched fresh cheese.

Monitoring, exposure and risk assessment of formaldehyde in alcoholic beverages in Korea

Formaldehyde occurs naturally in food and alcoholic beverages. Formaldehyde and alcoholic beverages can cause various health problems, including irritation of the eyes, nose, and throat, respiratory problems, and skin rashes. Alcoholic beverage samples (N = 236) were collected and analyzed for formaldehyde by liquid chromatography-tandem mass spectrometry. The highest average concentrations were detected in fruit wines (1.71 µg/g), followed by wines (1.15 µg/g), cheongju (0.95 µg/g), soju (0.85 µg/g), takju (0.64 µg/g) and beers (0.61 µg/g). We assessed the exposure and risk assessment to formaldehyde from alcoholic beverages based on the monitoring data for the general population and consumers in Korea using various schemes for point estimation. The daily intakes of formaldehyde for the general population and consumers were estimated to be 83 µg and 1202 µg, respectively. The mean hazard indexes (HI) for the general population and consumers in Korea were 0.009 and 0.132, respectively. On the other hand, the mean hazard indexes (HI) for the general population and consumers in Korea were 0.009 and 0.132, respectively. The exposure to formaldehyde in these alcoholic beverages for the Korean population was shown to be of low concern, but it is necessary to monitor the level of formaldehyde in alcoholic beverages and continuously conduct exposure assessment for consumers.

Study on the modulating effect of halogen atom substitution on the detection range of water content detection probes in organic solvents

Fluorescence probes based on the variations of aggregation state (Aggregation-Induced Emission (AIE) and Aggregation-Caused Quenching (ACQ)) have received widespread attention due to their simplicity, efficiency and intuitiveness. However, typical probes are highly sensitive to changes in polarity and slight variations in the external environment can cause a complete change in the aggregation state. With the aim of expanding the detection range of the molecular probe, this work adopts a different design strategy from adjusting the molecular backbone but regulates the fluorescence behavior of the Schiff base molecular backbone by introducing different halogen atoms. Systematic studies show that when chlorine serves as substitutional atoms (3,5-Cl Salen), the probe can achieve full-range detection of water content (0-100 vol%) in ethanol and DMF. To our knowledge, the 3,5-Cl Salen represents the best water content probe in organic molecules. Experimental and theoretical studies have shown that the adjustment of halogen atoms can linearly change the charge distribution on the benzene ring and precisely control the strength of intermolecular interactions. At the same time, we developed a fluorescent filter paper based on 3,5-Cl Salen and used smartphones for rapid, sensitive and precise on-site measurement of water content in organic solvents.

Biotechnological Potential of Microorganisms for Mosquito Population Control and Reduction in Vector Competence

Mosquitoes transmit pathogens that cause human diseases such as malaria, dengue fever, chikungunya, yellow fever, Zika fever, and filariasis. Biotechnological approaches using microorganisms have a significant potential to control mosquito populations and reduce their vector competence, making them alternatives to synthetic insecticides. Ongoing research has identified many microorganisms that can be used effectively to control mosquito populations and disease transmission. However, the successful implementation of these newly proposed approaches requires a thorough understanding of the multipronged microorganism-mosquito-pathogen-environment interactions. Although much has been achieved in discovering new entomopathogenic microorganisms, antipathogen compounds, and their mechanisms of action, only a few have been turned into viable products for mosquito control. There is a discrepancy between the number of microorganisms with the potential for the development of new insecticides and/or antipathogen products and the actual available products, highlighting the need for investments in the intersection of basic research and biotechnology.

Exploring the effects of the fermentation method on the quality of Lycium barbarum and Polygonatum cyrtonema compound wine based on LC-MS metabolomics

This study aimed to examine the effect of fermentation methods on the quality of Lycium barbarum and Polygonatum cyrtonema compound wine (LPW) by combining non-targeted metabolomic approaches with chemometrics and path profiling to determine the chemical and metabolic properties of LPW. The results demonstrated that SRA had higher leaching rates of total phenols and flavonoids, reaching 4.20 ± 0.10 v/v ethanol concentration. According to LC-MS non-targeting genomics, the metabolic profiles of LPW prepared by different mixtures of fermentation methods (Saccharomyces cerevisiae RW; Debaryomyces hansenii AS2.45) of yeast differed significantly. Amino acids, phenylpropanoids, flavonols, etc., were identified as the differential metabolites between different comparison groups. The pathways of tyrosine metabolism, biosynthesis of phenylpropanoids, and metabolism of 2-oxocarboxylic acids enriched 17 distinct metabolites. SRA stimulated the production of tyrosine and imparted a distinctive saucy aroma to the wine samples, providing a novel research concept for the microbial fermentation-based production of tyrosine.

Screening of Saccharomyces cerevisiae and Torulaspora delbrueckii strains in relation to their effect on malolactic fermentation

The use of Torulaspora delbrueckii in the alcoholic fermentation (AF) of grape must is increasingly studied and used in the wine industry. In addition to the organoleptic improvement of wines, the synergy of this yeast species with the lactic acid bacterium Oenococcus oeni is an interesting field of study. In this work, 60 strain combinations were compared: 3 strains of Saccharomyces cerevisiae (Sc) and 4 strains of Torulaspora delbrueckii (Td) in sequential AF, and four strains of O. oeni (Oo) in malolactic fermentation (MLF). The objective was to describe the positive or negative relationships of these strains with the aim of finding the combination that ensures better MLF performance. In addition, a new synthetic grape must has been developed that allows the success of AF and subsequent MLF. Under these conditions, the Sc-K1 strain would be unsuitable for carrying out MLF unless there is prior inoculation with Td-Prelude, Td-Viniferm or Td-Zymaflore always with the Oo-VP41 combination. However, from all the trials performed, it appears that the combinations of sequential AF with Td-Prelude and Sc-QA23 or Sc-CLOS, followed by MLF with Oo-VP41, reflected a positive effect of T. delbrueckii compared to inoculation of Sc alone, such as a reduction in L-malic consumption time. In conclusion, the obtained results highlight the relevance of strain selection and yeast-LAB strain compatibility in wine fermentations. The study also reveals the positive effect on MLF of some T. delbrueckii strains.

Using wild yeasts to modulate the aroma profile of low-alcoholic meads

In recent years, ample research has focused on applying wild (especially non-Saccharomyces) yeasts in producing alcoholic beverages. Common characteristics of wild yeast strains include simultaneous high production of fruity and floral aroma compounds and low ethanol production. In this study, mead starter cultures were selected based on preliminary screening of wild yeast strains from a Brazilian culture collection (n = 63) for their ability to produce aroma-active compounds. The selected strains included one strain of Saccharomyces cerevisiae and three non-Saccharomyces strains (Pichia jadinii, Torulaspora delbrueckii, and Kluyveromyces lactis). These strains were used to ferment honey must prepared with Aroeira honey, adjusted to 24°Brix, which took 36 days to complete. Single culture fermentations and co-fermentations with S. cerevisiae and non-Saccharomyces strains were carried out. The quality of the produced beverages was evaluated by sugar consumption and production of alcohols and organic acids, analyzed with high-performance liquid chromatography. The volatile organic compound composition was analyzed with gas chromatography-mass spectrometry. Meads with various ethanol amounts (4.7-11.0% v/v) and residual sugar contents (70.81-160.25 g l-1) were produced. In addition, in both single-strain fermentation and co-fermentation with S. cerevisiae, meads produced with either Torulaspora delbrueckii or Kluyveromyces lactis had a roughly three-fold higher content of honey-aroma compound phenethyl acetate and a higher hedonic impression score than meads produced with only S. cerevisiae. These results demonstrated non-Saccharomyces yeasts' ability to increase aroma complexity and improve the sensory quality of low-alcoholic meads.

Unveiling the Microbial Ecology behind Mezcal: A Spirit Drink with a Growing Global Demand

The advent of omics has expanded our knowledge of microbial ecology behind Mezcal, a fermented spirit made from the juices of cooked Agave plants (Agave spp., Asparagaceae). Mezcal has been produced in Mexico for over 200 years, however, has been in high demand since its discovery by international markets in the last decade. Mezcal is appreciated for its diverse and complex sensory profile, which is tied to the geographic and environmental diversity of the different Mezcal-producing regions. This regional typicity is brought about by spontaneous fermentation consortia that act in loosely controlled artisanal fermentation processes. Previous works have mainly concentrated on microorganisms involved in the biosynthesis of alcohol and other volatile compounds, or from a different perspective, on culturable microorganisms (mainly yeasts) influencing the taste profile. Attention has been aimed at the richness of microbial populations in point events or under laboratory conditions, which leaves much of the biological richness out of account. Omics techniques have become powerful tools for characterizing the composition of autochthonous fermentation microbiota, regional or endemic features, and ecological processes that determine the dynamics of Mezcal fermentation. The analyses of genetic material, proteins, and metabolites allow disentangling the biological complexity of Mezcal production. This review presents the reader with an up-to-date overview of publications that discuss microbial communities in Mezcal fermentation, metabolic pathways regulated by microbial interactions, and the application of omics to characterize the spontaneous fermenting microbiota conformation and dynamics considering the subjacent ecological processes.

Recent Developments in Surface-Enhanced Raman Spectroscopy and Its Application in Food Analysis: Alcoholic Beverages as an Example

Surface-enhanced Raman spectroscopy (SERS) is an emerging technology that combines Raman spectroscopy and nanotechnology with great potential. This technology can accurately characterize molecular adsorption behavior and molecular structure. Moreover, it can provide rapid and sensitive detection of molecules and trace substances. In practical application, SERS has the advantages of portability, no need for sample pretreatment, rapid analysis, high sensitivity, and ‘fingerprint’ recognition. Thus, it has great potential in food safety detection. Alcoholic beverages have a long history of production in the world. Currently, a variety of popular products have been developed. With the continuous development of the alcoholic beverage industry, simple, on-site, and sensitive detection methods are necessary. In this paper, the basic principle, development history, and research progress of SERS are summarized. In view of the chemical composition, the beneficial and toxic components of alcoholic beverages and the practical application of SERS in alcoholic beverage analysis are reviewed. The feasibility and future development of SERS are also summarized and prospected. This review provides data and reference for the future development of SERS technology and its application in food analysis.

Single Cell Proteins production from food processing effluents and digestate

The increase in human population determines a higher proteins request to sustain the feed demand for animals and aquaculture. Single Cell Proteins (SCPs) consist of mixed protein from pure and mixed culture of bacteria, fungi, algae, and yeast, which are grown and harvested to accomplish the food requirement of human and animals. This work investigated the production of Saccharomyces cerevisiae to be used as SCPs for animal feeding. The effluent of candies production process, rich in sugars, about 40 g/L, and agricultural digestate rich in nitrogen and other macro and micronutrients, were used for the yeast's growth. Preliminary batch tests demonstrated that aerobic conditions optimized the biomass growth. Then, continuous aerobic tests were conducted at different dilution rates. The dilution rate of 0.50 d^-1, corresponding to a hydraulic retention time of 2 days, optimized both the biomass productivity of 0.25 g/L per day and the protein content of 28% w/w. The analysis of the aminoacidic profile demonstrated that obtained SCPs could be used as an integrator of feed for fish and monogastric animals. On the contrary, they were not suitable for pet feed as all the amino acids concentrations were lower than required standards. These results suggested that anaerobic digesters in the agricultural sector can be transformed into small biorefineries for microbial protein production.

Microbial Communities in Retail Draft Beers and the Biofilms They Produce

In the beer brewing industry, microbial spoilage presents a consistent threat that must be monitored and controlled to ensure the palatability of a finished product. Many of the predominant beer spoilage microbes have been identified and characterized, but the mechanisms of contamination and persistence remain an open area of study. Postproduction, many beers are distributed as kegs that are attached to draft delivery systems in retail settings where ample opportunities for microbial spoilage are present. As such, restaurants and bars can experience substantial costs and downtime for cleaning when beer draft lines become heavily contaminated. Spoilage monitoring on the retail side of the beer industry is often overlooked, yet this arena may represent one of the largest threats to the profitability of a beer if its flavor profile becomes substantially distorted by contaminating microbes. In this study, we sampled and cultured microbial communities found in beers dispensed from a retail draft system to identify the contaminating bacteria and yeasts. We also evaluated their capability to establish new biofilms in a controlled setting. Among four tested beer types, we identified over a hundred different contaminant bacteria and nearly 20 wild yeasts. The culturing experiments demonstrated that most of these microbes were viable and capable of joining new biofilm communities. These data provide an important reference for monitoring specific beer spoilage microbes in draft systems and we provide suggestions for cleaning protocol improvements.

IMPORTANCE Beer production, packaging, and service are each vulnerable to contamination by microbes that metabolize beer chemicals and impart undesirable flavors, which can result in the disposal of entire batches. Therefore, great effort is taken by brewmasters to reduce and monitor contamination during production and packaging. A commonly overlooked quality control stage of a beer supply chain is at the retail service end, where beer kegs supply draft lines in bars and restaurants under nonsterile conditions. We found that retail draft line contamination is rampant and that routine line cleaning methods are insufficient to efficiently suppress beer spoilage. Thus, many customers unknowingly consume spoiled versions of the beers they consume. This study identified the bacteria and yeast that were resident in retail draft beer samples and also investigated their abilities to colonize tubing material as members of biofilm communities.