Microorganisms in Whole Botanical Fermented Foods Survive Processing and Simulated Digestion to Affect Gut Microbiota Composition

Botanical fermented foods have been shown to improve human health, based on the activity of potentially beneficial lactic acid bacteria (LAB) and yeasts and their metabolic outputs. However, few studies have explored the effects of prolonged storage and functional spices on microbial viability of whole fermented foods from fermentation to digestion. Even fewer have assessed their impact on the gut microbiota. Our study investigated the effects of production processes on LAB and yeast microbial viability and gut microbiota composition. We achieved this by using physicochemical assessments and an in vitro gastrointestinal and a porcine gut microbiota model. In low-salt sauerkraut, we assessed the effects of salt concentration, starter cultures, and prolonged storage, and in tibicos, prolonged storage and the addition of spices cayenne, ginger, and turmeric. In both food matrices, LAB counts significantly increased (p<0.05), reaching a peak of 7–8 log cfu/g, declining to 1–1.5 log cfu/g by day 96. Yeast viability remained at 5–6 log cfu/g in tibicos. Ginger tibicos had significantly increased LAB and yeast viability during fermentation and storage (p<0.05). For maximum microbial consumption, tibicos should be consumed within 28days, and sauerkraut, 7weeks. Simulated upper GI digestion of both products resulted in high microbial survival rates of 70–80%. The 82% microbial survival rate of cayenne tibicos was significantly higher than other treatments (p<0.05). 16S rRNA sequencing of simulated porcine colonic microbiota showed that both spontaneously fermented sauerkraut and tibicos increase the relative abundance of Megasphaera 85-fold. These findings will inform researchers, producers, and consumers about the factors that affect the microbial content of fermented foods, and their potential effects on the gut.

Antiaging and Skin Irritation Potential of Four Main Indonesian Essential Oils

Essential oils possess antiaging properties due to their antioxidant activity. This study aims to determine the antiaging activities of four main Indonesian essential oils and their irritation potential on the skin. The spot yeast and in vivo rat skin with UVB exposure methods were used to analyze the antiaging activity of essential oils on aging triggered by endogenous and exogenous factors, respectively. Meanwhile, patch tests and clinical evaluations were used for the skin irritation potential analysis. The antiaging activity results from the endogenous factor showed that the use of clove, patchouli, nutmeg, and citronella oils increased yeast viability at concentrations of 20, 40, 60, and 100 µg/mL, respectively. Furthermore, nutmeg, cloves, citronella, and patchouli oils decreased the wrinkle score on rat skin after UVB exposure (exogenous factor). The skin irritation potential results of patchouli, nutmeg, citronella, and clove oils were none (0), slightly (0.02), moderately (0.09), and very irritating (0.39), respectively.

Antifungal activity of fibrate-based compounds and substituted pyrroles inhibiting the enzyme 3-hydroxy-methyl-glutaryl-CoA reductase of Candida glabrata (CgHMGR), and decreasing yeast viability and ergosterol synthesis

ABSTRACTDue to the emergence of multi-drug resistant strains of yeasts belonging to the Candida genus, there is an urgent need to discover antifungal agents directed at alternative molecular targets. The aim of the current study was to evaluate the capacity of synthetic compounds to inhibit the Candida glabrata enzyme denominated 3-hydroxy-methyl-glutaryl-CoA reductase (CgHMGR), and thus affect ergosterol synthesis and yeast viability. One series of synthetic antifungal compounds were analogues to fibrates, a second series had substituted 1,2-dihydroquinolines and the third series included substituted pyrroles. α-asarone-related compounds 1c and 5b with a pyrrolic core were selected as the best antifungal candidates. Both inhibited the growth of fluconazole-resistant C. glabrata 43 and fluconazole-susceptible C. glabrata CBS 138. A yeast growth rescue experiment based on the addition of exogenous ergosterol showed that the compounds act by inhibiting the mevalonate synthesis pathway. A greater recovery of yeast growth occurred for the C. glabrata 43 strain and after the 1c (versus 5b) treatment. Given that the compounds decreased the ergosterol concentration in the yeast strains, they probably target the ergosterol synthesis. According to the docking analysis, the inhibitory effect of the 1c and 5b could possibly be mediated by their interaction with the amino acid residues of the catalytic site of CgHMGR. Since 1c displayed higher binding energy than α-asarone and 5b, it is a good candidate for further research, which should include structural modifications to increase its specificity and potency as well as in vivo studies on its effectiveness at a therapeutic dose.HIGHLIGHTSFibrate-based and pyrrole-containing compounds were tested as C. glabrata inhibitors.The best inhibitor from fibrate was 1c and from pyrroles was 5b.These agents inhibited C. glabrata growth better than the reference antifungals.They also inhibited ergosterol synthesis by the two C. glabrata strains tested. Experimental

Baker’s Yeast-Based Microbial Fuel Cell Mediated by 2-Methyl-1,4-Naphthoquinone

Microbial fuel cell (MFC) efficiency depends on charge transfer capability from microbe to anode, and the application of suitable redox mediators is important in this area. In this study, yeast viability experiments were performed to determine the 2-methyl-1,4-naphthoquinone (menadione (MD)) influence on different yeast cell species (baker’s yeast and Saccharomyces cerevisiae yeast cells). In addition, electrochemical measurements to investigate MFC performance and efficiency were carried out. This research revealed that baker’s yeast cells were more resistant to dissolved MD, but the current density decreased when yeast solution concentration was incrementally increased in the same cell. The maximal calculated power of a designed baker’s yeast-based MFC cell anode was 0.408 mW/m2 and this power output was registered at 24 mV. Simultaneously, the cell generated a 62-mV open circuit potential in the presence of 23 mM potassium ferricyanide and the absence of glucose and immobilized MD. The results only confirm that MD has strong potential to be applied to microbial fuel cells and that a two-redox-mediator-based system is suitable for application in microbial fuel cells.

Probiotic Efficacy of Microencapsulated Saccharomyces cerevisiae on Gastrointestinal Tract Integrity in Rats

Saccharomyces cerevisiae as a probiotic has been prescribed for prophylaxis and treatment of gut infected diseases. This study was designed to assess the effects of encapsulated S. cerevisiae on gastrointestinal tract properties in the animal model. In rats, after 8-week feeding by encapsulated and unencapsulated S. cerevisiae, the mount of the IgA protein was determined by ELISA. Rats were euthanized, and the liver, kidney, and intestinal tract were collected for histological analysis. The consumption of S. cerevisiae could increase IgA levels in comparison with the control group. This increase was significant in the lower parts of the small intestine (p<0.05). In histopathological evaluations; Liver microscopic examination showed fatty change and margination of Kupffer cells as well as their hyperplasia and hypertrophy, which is a mark for liver regeneration in both groups that received microencapsulated and free probiotic. In spleen structure, in both groups, mild inflammation of the spleen tissue in the form of accumulation of red pulp of erythrocytes, hypercellular of this tissue was observed due to hyperplasia of lymphoid follicles and hyperplasia and hepaticophyta of retinal cells and macrophages. The lymphatic structure of the spleen showed relatively intense hyperplasia. In the colon structure, in both groups, hyperplasia of goblet calls along with slight infiltration of inflammatory cells was noted. Calcium alginate encapsulation considerably improves the yeast viability in simulated gastric juice and simulated intestine juice situations. Also, S. cerevisiae has positive profits in suitable food absorption and then decreasing diarrhea and other similar gastrointestinal disorders.

Effects of Combined α-Amylase and Endo-Xylanase Treatments on the Properties of Fresh and Frozen Doughs and Final Breads

Frozen bread doughs usually exhibit less bread volume and poor texture due to dough weakening as well as reduced yeast viability. The objectives of this study were to improve the textural properties of frozen bread dough by applying carbohydrate-active enzymes, α-amylase and endo-xylanase. Each enzyme was applied to dough formulation at 20 (748 and 3.5 units, respectively) and 100 ppm levels of flour, and their combined treatments were also applied. Enzyme-treated doughs were kept frozen at −20 °C for 2 weeks, and then baked following the official American Association of Cereal Chemists (AACC) method. A texture profile analysis of oven-baked breads was performed at 25 °C after a 5-day storage period. α-Amylase treatment at a 100 ppm level increased the specific bread volume by 24.5% and 21.9% when compared to untreated fresh and frozen bread doughs, respectively, and decreased crumb hardness by 63.4% and 58.3%; endo-xylanase (100 ppm) also decreased crumb hardness by 56.9% and 26.9%. The combined use of α-amylase and endo-xylanase retarded bread hardening synergistically after a 5-day storage period.

Long-Term Adaption to High Osmotic Stress as a Tool for Improving Enological Characteristics in Industrial Wine Yeast

Industrial wine yeasts owe their adaptability in constantly changing environments to a long evolutionary history that combines naturally occurring evolutionary events with human-enforced domestication. Among the many stressors associated with winemaking processes that have potentially detrimental impacts on yeast viability, growth, and fermentation performance are hyperosmolarity, high glucose concentrations at the beginning of fermentation, followed by the depletion of nutrients at the end of this process. Therefore, in this study, we subjected three widely used industrial wine yeasts to adaptive laboratory evolution under potassium chloride (KCl)-induced osmotic stress. At the end of the evolutionary experiment, we evaluated the tolerance to high osmotic stress of the evolved strains. All of the analyzed strains improved their fitness under high osmotic stress without worsening their economic characteristics, such as growth rate and viability. The evolved derivatives of two strains also gained the ability to accumulate glycogen, a readily mobilized storage form of glucose conferring enhanced viability and vitality of cells during prolonged nutrient deprivation. Moreover, laboratory-scale fermentation in grape juice showed that some of the KCl-evolved strains significantly enhanced glycerol synthesis and production of resveratrol-enriched wines, which in turn greatly improved the wine sensory profile. Altogether, these findings showed that long-term adaptations to osmotic stress can be an attractive approach to develop industrial yeasts.

Influence of Storage Temperature and Packaging on Bacteria and Yeast Viability in a Plant-Based Fermented Food

Optimization of food storage has become a central issue for food science and biotechnology, especially in the field of functional foods. The aim of this work was to investigate the influence of different storage strategies in a fermented food product (FFP) and further determine whether the regular storage (room temperature (RT) and standard packaging (SP)) could be refined. Eight experimental conditions (four different temperatures × two packaging) were simulated and changes in FFP’s microbial ecology (total bacteria, lactic acid bacteria (LAB), and yeasts) and physicochemical characteristics (pH and moisture content (MC)) were determined following 1, 3, 6, and 12 months. All conditions tested showed a decline in microbial content due to the effect of the temperature, 37 °C being the most detrimental condition, while −20 and 4 °C seemed to be better than RT in some parameters. Vacuum packaging (VP) only had a major effect on MC and we found that VP preserved greater MC values than SP at 3, 6, and 12 months. The correlation analysis revealed that total bacteria, LAB, and yeasts were positively associated, and also both pH and MC showed a correlation. According to our results and with the purpose to maintain the load of viable microorganisms, we observed that the best storage conditions should contemplate SP and freezing or cooling temperature during a period no longer than 3 months.

Karvakrol İlavesinin Zygosaccharomyces bailii ile Kontamine Edilmiş Elma Suyunda Bazı Fizikokimyasal ve Biyoaktif Özelliklerin Değişimi Üzerindeki Etkisinin İncelenmesi

In this study, the effects of carvacrol addition which is a natural preservative to apple juice samples contaminated with Z. bailii which is an osmotolerant yeast and shows resistance against high sugar concentration, low acidity, ethanol content and pasteurization process, were investigated on some physicochemical and bioactive properties and also changes in yeast numbers during storage period. For this purpose, the response surface methodology was applied and storage time (1-41 days), storage temperature (4-20°C), sodium benzoate amount (0-0.1%) and carvacrol amount (0-750 ppm) were selected as processing variables. Significant changes in physicochemical properties were observed due to yeast viability occurred during the storage of apple juice samples. The increase in the amount of carvacrol caused a decrease in the number of yeasts about 7 log level and prevented the spoilage of fruit juices. However, the brix value of the samples without carvacrol showed a decrease of 50% as a result of yeast activity and the fruit juice could not be consumed. Total phenolic content of the sample was in the range of 136.7-645.7 mg GAE/L and the lowest total phenolic content was determined for the run 11 having no carvacrol while the highest total phenolic content was for the sample added with the highest carvacrol level. As a result of the optimization process, it was observed that the deterioration activities of Z. bailii could be prevented to a great extent by the addition of maximum amount of carvacrol.

Silver Nanoparticles Addition in Poly(Methyl Methacrylate) Dental Matrix: Topographic and Antimycotic Studies

The widespread use of nanoparticles (NPs) in medical devices has opened a new scenario in the treatment and prevention of many diseases and infections owing to unique physico-chemical properties of NPs. In this way, silver nanoparticles (AgNPs) are known to have a strong antimicrobial activity, even at low concentrations, due to their ability to selectively destroy cellular membranes. In particular, in the field of dental medicine, the use of AgNPs in different kinds of dental prosthesis matrixes could be a fundamental tool in immunodepressed patients that suffer of different oral infections. Candida albicans (C. albicans), an opportunistic pathogenic yeast with high colonization ability, is one of the causative agents of oral cavity infection. In our work, we added monodispersed citrate-capping AgNPs with a size of 20 nm at two concentrations (3 wt% and 3.5 wt%) in poly(methyl methacrylate) (PMMA), the common resin used to develop dental prostheses. After AgNPs characterization, we evaluated the topographical modification of PMMA and PMMA with the addition of AgNPs by means of atomic force microscopy (AFM), showing the reduction of surface roughness. The C. albicans colonization on PMMA surfaces was assessed by the Miles and Misra technique as well as by scanning electron microscopy (SEM) at 24 h and 48 h with encouraging results on the reduction of yeast viability after AgNPs exposure.