Yeasts as probiotics: Mechanisms, outcomes, and future potential

Advancements in gene editing technologies for probiotic-enabled disease therapy

Probiotics typically refer to microorganisms that have been identified for their health benefits, and they are added to foods or supplements to promote the health of the host. A growing number of probiotic strains have been identified lately and developed into valuable regulatory pharmaceuticals for nutritional and medical applications. Gene editing technologies play a crucial role in addressing the need for safe and therapeutic probiotics in disease treatment. These technologies offer valuable assistance in comprehending the underlying mechanisms of probiotic bioactivity and in the development of advanced probiotics. This review aims to offer a comprehensive overview of gene editing technologies applied in the engineering of both traditional and next-generation probiotics. It further explores the potential for on-demand production of customized products derived from enhanced probiotics, with a particular emphasis on the future of gene editing in the development of live biotherapeutics.

Isolate distribution and antifungal susceptibility of Saccharomyces cerevisiae in the national regional medical center of Southwest China for women and children during 2018-2023

BACKGROUND

Saccharomyces cerevisiae has been considered a harmless yeast, but in recent years, increasing evidence has shown that it can cause disease in humans, especially invasive infections in infants/children and vulvovaginal infections in women. This study aimed to investigate the clinical information and antifungal susceptibility of clinical cases with S. cerevisiae and establish a foundation for the prevention and treatment of fungal infections.

METHODS

This study was conducted from May 2018 to May 2023 at a national regional medical center in Southwest China for women and children. The demographic and clinical characteristics of patients isolated with S. cerevisiae were collected and analyzed. All the isolates were cultured on Sabouraud medium plates and identified by MALDI-TOF MS. The antifungal susceptibility of S. cerevisiae to 10 agents (amphotericin B, fluconazole, itraconazole, voriconazole, micafungin, caspofungin, terbinafine and 5-flucytosine) was determined via the microdilution broth method to determine the minimum inhibitory concentrations (MICs).

RESULTS

A total of 75 cases of S. cerevisiae isolated from patients with vulvovaginal candidiasis (VVC, 44 cases), pneumonia (13 cases), or diarrhea (18 cases) were included after data review. The MICs of voriconazole and flucytosine for S. cerevisiae isolated from different body sites differed, with higher resistance in intestinal isolates. In this study, S. cerevisiae caused VVC, but there was no clear evidence that it was involved in pneumonia or diarrhea. Compared with those of Candida albicans, the primary pathogen of VVC, the MICs of fluconazole (11.96 ± 5.78 µg/mL vs. 67.64 ± 16.62 µg/mL, p = 0.002), itraconazole (0.77 ± 0.19 µg/mL vs. 2.31 ± 0.53 µg/mL, p = 0.008), voriconazole (0.22 ± 0.09 µg/mL vs. 5.02 ± 1.09 µg/mL, p < 0.001), and terbinafine (10.41 ± 0.84 µg/mL vs. 14.93 ± 4.77 µg/mL, p < 0.001) for S. cerevisiae (isolated from the genital tract) were significantly lower, while those of micafungin (0.14 ± 0.01 µg/mL vs. 0.06 ± 0.01 µg/mL, p < 0.001) and caspofungin (0.27 ± 0.04 µg/mL vs. 0.06 ± 0.01 µg/mL, p < 0.001) were significantly greater.

CONCLUSION

Azoles remain the recommended regimen for S. cerevisiae-related VVC, and the use of amphotericin B vaginal effervescent tablets could be considered for the treatment of azole-resistant isolates. The antifungal susceptibility of S. cerevisiae varies according to the isolated source, and the pathogenicity trend of S. cerevisiae should be studied.

Evaluation of probiotic efficacy of indigenous yeast strain, Saccharomyces cerevisiae Y-89 isolated from a traditional fermented beverage of West Bengal, India having protective effect against DSS-induced colitis in experimental mice

Increasing awareness regarding health promotion and disease prevention has driven inclusion of fermented foods and beverages in the daily diet. These are the enormous sources of beneficial microbes, probiotics. This study aims to isolate yeast strains having probiotic potential and effectivity against colitis. Initially, ninety-two yeast strains were isolated from Haria, an ethnic fermented beverage of West Bengal, India. Primary screening was done by their acid (pH 4) and bile salt (0.3%) tolerance ability. Four potent isolates were selected and found effective against Entamoeba histolytica, as this human pathogen is responsible to cause colitis. They were identified as Saccharomyces cerevisiae. They showed luxurious growth even at 37 oC, tolerance up to 5% of NaCl, resistance to gastric juice and high bile salt (2.0%) and oro-gastrointestinal transit tolerance. They exhibited good auto-aggregation and co-aggregation ability and strong hydrophobicity. Finally, heat map and principal component analysis revealed that strain Y-89 was the best candidate. It was further characterised and found to have significant protective effects against DSS-induced colitis in experimental mice model. It includes improvement in colon length, body weight and organ indices; reduction in disease activity index; reduction in cholesterol, LDL, SGPT, SGOT, urea and creatinine levels; improvement in HDL, ALP, total protein and albumin levels; decrease in coliform count and restoration of tissue damage. This study demonstrates that the S. cerevisiae strain Y-89 possesses remarkable probiotic traits and can be used as a potential bio-therapeutic candidate for the prevention of colitis.

Encapsulation of Saccharomyces spp. for Use as Probiotic in Food and Feed: Systematic Review and Meta-analysis

Probiotics, particularly yeasts from the genus Saccharomyces, are valuable for their health benefits and potential as antibiotic alternatives. To be effective, these microorganisms must withstand harsh environmental conditions, necessitating advanced protective technologies such as encapsulation to maintain probiotic viability during processing, storage, and passage through the digestive system. This review and meta-analysis aims to describe and compare methods and agents used for encapsulating Saccharomyces spp., examining operating conditions, yeast origins, and species. It provides an overview of the literature on the health benefits of nutritional yeast consumption. A bibliographic survey was conducted following the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. The meta-analysis compared encapsulation methods regarding their viability after encapsulation and exposure to the gastrointestinal tract. Nineteen studies were selected after applying inclusion/exclusion criteria. Freeze drying was found to be the most efficient for cell survival, while ionic gelation was best for maintaining viability after exposure to the gastrointestinal tract. Consequently, the combination of freeze drying and ionic gelation proved most effective in maintaining high cell viability during encapsulation, storage, and consumption. Research on probiotics for human food and animal feed indicates that combining freeze drying and ionic gelation effectively protects Saccharomyces spp.; however, industrial scalability must be considered. Reports on yeast encapsulation using agro-industrial residues as encapsulants offer promising strategies for preserving potential probiotic yeasts, contributing to the environmental sustainability of industrial processes.

Probiotics as a Therapeutic Approach for Non-infectious Gastric Ulcer Management: a Comprehensive Review

A gastric ulcer is a stomach lining or nearby intestine disruption caused by acid and pepsin. Helicobacter pylori (H. pylori) and NSAIDs are the primary culprits behind stomach infections that can lead to gastric ulcers and other digestive disorders. Additionally, lifestyle choices such as alcohol consumption and cigarette smoking, stress, and exposure to cold environments can also contribute to non-infectious gastric ulcers. Various treatments are available for gastric ulcers, including antibiotics, anticholinergics, and antacids. However, potential concerns include antibiotic resistance, side effects, and treatment failure. Considering this, there is a need for an alternative approach to manage it. Fortunately, probiotics, typically Lactobacillus and Bifidobacterium, show potential for healing gastric ulcers, offering a non-invasive alternative to conventional treatments. A notable concern arises from applying probiotic bacteria stemming from the propensity of pathogenic bacteria to develop antimicrobial resistance in response to antibiotic therapies. Therefore, the use of yeast becomes more imperative due to its natural resistance to antibacterial antibiotics for antibacterial-treated patients. Probiotic bacteria and yeasts could heal gastric ulcers by regulating the immune response, reducing inflammation, and restoring the balance between defensive and aggressive factors of the gastric layer. This comprehensive review provides an in-depth analysis of the benefits of probiotics and their potential as a therapeutic treatment for non-infectious gastric ulcers, along with other probiotic options. In particular, this review provides a succinct summary of multiple literature studies on probiotics, emphasising the distinctive properties of yeast probiotics, as well as their (bacteria and yeasts) application in the management of non-infectious gastric ulcers.

Probiotic Yeasts: A Developing Reality?

Yeasts are gaining increasing attention for their potential health benefits as probiotics in recent years. Researchers are actively searching for new yeast strains with probiotic properties (i.e, Debaryomyces hansenii; Kluyveromyces marxianus; Yarrowia lipolytica; Pichia hudriavzevii; and Torulaspora delbrueckii) from various sources, including traditional fermented foods, the human gut, and the environment. This exploration is expanding the pool of potential probiotic yeasts beyond the well-studied Saccharomyces boulardii. Research suggests that specific yeast strains possess properties that could be beneficial for managing conditions like inflammatory bowel disease, irritable bowel syndrome, skin disorders, and allergies. Additionally, probiotic yeasts may compete with pathogenic bacteria for adhesion sites and nutrients, thereby inhibiting their growth and colonization. They might also produce antimicrobial compounds that directly eliminate harmful bacteria. To achieve these goals, the approach that uses probiotics for human health is changing. Next-generation yeast probiotics are emerging as a powerful new approach in the field of live biotherapeutics. By using genetic engineering, scientists are able to equip these tools with specialized capabilities. However, most research on these probiotic yeasts is still in its early stages, and more clinical trials are needed to confirm their efficacy and safety for various health conditions. This review could provide a brief overview of the situation in this field.

Non-lactic acid bacteria probiotics isolated from intestine or various circumstances

Probiotics are live microorganisms beneficial to host health, predominantly comprising lactic acid bacteria (LAB) such as Lactobacillus. Additional non-LAB probiotics, termed intestinal isolates, encompass next-generation strains like Akkermansia muciniphila, Faecalibacterium prausnitzii, Christensenella minuta, Anaerobutyricum soehngenii, Oxalobacter formigenes, etc. and alongside externally sourced Bacillus, Saccharomyces cerevisiae, Clostridium butyricum, and Propionibacterium. Intestinal-derived probiotics represent strictly anaerobic strains with challenging culturing requirements, contrasting with the aerobic nature of Bacillus probiotics and the ease of culturing S. cerevisiae. These strains exhibit diverse health-promoting properties, encompassing antimicrobial, anticancer, antioxidant, and vitamin production capabilities, albeit contingent upon strain specificity. This review delineates the characteristics, culturing conditions, and health advantages associated with non-LAB probiotics.

Programming Probiotics: Diet-Responsive Gene Expression and Colonization Control in Engineered S. boulardii

Saccharomyces boulardii (Sb) is an emerging probiotic chassis for delivering biomolecules to the mammalian gut, offering unique advantages as the only eukaryotic probiotic. However, precise control over gene expression and gut residence time in Sb have remained challenging. To address this, we developed five ligand-responsive gene expression systems and repaired galactose metabolism in Sb, enabling inducible gene expression in this strain. Engineering these systems allowed us to construct AND logic gates, control the surface display of proteins, and turn on protein production in the mouse gut in response to dietary sugar. Additionally, repairing galactose metabolism expanded Sb's habitat within the intestines and resulted in galactose-responsive control over gut residence time. This work opens new avenues for precise dosing of therapeutics by Sb via control over its in vivo gene expression levels and localization within the gastrointestinal tract.

Next generation probiotics: Engineering live biotherapeutics

The population dynamics of the human microbiome have been associated with inflammatory bowel disease, cancer, obesity, autoimmune diseases, and many other human disease states. An emerging paradigm in treatment is the administration of live engineered organisms, also called next-generation probiotics. However, the efficacy of these microbial therapies can be limited by the organism's overall performance in the harsh and nutrient-limited environment of the gut. In this review, we summarize the current state of the art use of bacterial and yeast strains as probiotics, highlight the recent development of genetic tools for engineering new therapeutic functions in these organisms, and report on the latest therapeutic applications of engineered probiotics, including recent clinical trials. We also discuss the supplementation of prebiotics as a method of manipulating the microbiome and improving the overall performance of engineered live biotherapeutics.

What is the role of microbial biotechnology and genetic engineering in medicine?

Microbial products are essential for developing various therapeutic agents, including antibiotics, anticancer drugs, vaccines, and therapeutic enzymes. Genetic engineering techniques, functional genomics, and synthetic biology unlock previously uncharacterized natural products. This review highlights major advances in microbial biotechnology, focusing on gene-based technologies for medical applications.

A comprehensive guide to assess gut mycobiome and its role in pathogenesis and treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is an immune mediated chronic inflammatory disorder of gastrointestinal tract, which has underlying multifactorial pathogenic determinants such as environmental factors, susceptibility genes, gut microbial dysbiosis and a dysregulated immune response. Human gut is a frequent inhabitant of complex microbial ecosystem encompassing bacteria, viruses, parasites, fungi and other microorganisms that have an undisputable role in maintaining balanced homeostasis. All of these microbes interact with immune system and affect human gut physiology either directly or indirectly with interaction of each other. Intestinal fungi represent a smaller but crucial component of the human gut microbiome. Besides interaction with bacteriome and virome, it helps in balancing homoeostasis between pathophysiological and physiological processes, which is often dysregulated in patients with IBD. Understanding of gut mycobiome and its clinical implications are still in in its infancy as opposed to bacterial component of gut microbiome, which is more often focused. Modulation of gut mycobiome represents a novel and promising strategy in the management of patients with IBD. Emerging mycobiome-based therapies such as diet interventions, fecal microbiota transplantation (FMT), probiotics (both fungal and bacterial strains) and antifungals exhibit substantial effects in calibrating the gut mycobiome and restoring dysbalanced immune homeostasis by restoring the core gut mycobiome. In this review, we summarized compositional and functional diversity of the gut mycobiome in healthy individuals and patients with IBD, gut mycobiome dysbiosis in patients with IBD, host immune-fungal interactions and therapeutic role of modulation of intestinal fungi in patients with IBD.

New biomarkers underlying acetic acid tolerance in the probiotic yeast Saccharomyces cerevisiae var. boulardii

Evolutionary engineering experiments, in combination with omics technologies, revealed genetic markers underpinning the molecular mechanisms behind acetic acid stress tolerance in the probiotic yeast Saccharomyces cerevisiae var. boulardii. Here, compared to the ancestral Ent strain, evolved yeast strains could quickly adapt to high acetic acid levels (7 g/L) and displayed a shorter lag phase of growth. Bioinformatic-aided whole-genome sequencing identified genetic changes associated with enhanced strain robustness to acetic acid: a duplicated sequence in the essential endocytotic PAN1 gene, mutations in a cell wall mannoprotein (dan4Thr192del), a lipid and fatty acid transcription factor (oaf1Ser57Pro) and a thiamine biosynthetic enzyme (thi13Thr332Ala). Induction of PAN1 and its associated endocytic complex SLA1 and END3 genes was observed following acetic acid treatment in the evolved-resistant strain when compared to the ancestral strain. Genome-wide transcriptomic analysis of the evolved Ent acid-resistant strain (Ent ev16) also revealed a dramatic rewiring of gene expression among genes associated with cellular transport, metabolism, oxidative stress response, biosynthesis/organization of the cell wall, and cell membrane. Some evolved strains also displayed better growth at high acetic acid concentrations and exhibited adaptive metabolic profiles with altered levels of secreted ethanol (4.0-6.4% decrease), glycerol (31.4-78.5% increase), and acetic acid (53.0-60.3% increase) when compared to the ancestral strain. Overall, duplication/mutations and transcriptional alterations are key mechanisms driving improved acetic acid tolerance in probiotic strains. We successfully used adaptive evolutionary engineering to rapidly and effectively elucidate the molecular mechanisms behind important industrial traits to obtain robust probiotic yeast strains for myriad biotechnological applications. KEY POINTS: •Acetic acid adaptation of evolutionary engineered robust probiotic yeast S. boulardii •Enterol ev16 with altered genetic and transcriptomic profiles survives in up to 7 g/L acetic acid •Improved acetic acid tolerance of S. boulardii ev16 with mutated PAN1, DAN4, OAF1, and THI13 genes.

The effect of probiotic supplementation on the clinical and para-clinical findings of multiple sclerosis: a randomized clinical trial

Multiple Sclerosis (MS) is a chronic demyelination disease of the central nervous system (CNS). The gut-brain axis involves communication between the nervous, endocrine, and immune systems. Probiotics can positively impact immune and inflammatory responses by regulating gut microbiota. A total of 40 MS patients (average age of 34.38 ± 6.65) were examined to determine the effect of the Saccharomyces boulardii supplement for four months compared to a placebo. The results showed that the Saccharomyces boulardii significantly decreased the inflammatory marker high-sensitivity C-reactive protein (hs-CRP) compared to the placebo (P < 0.001). The serum antioxidant capacity (TAC) also increased significantly in the probiotic group compared to the placebo (p = 0.004). Both the probiotic and placebo groups showed a reduction in the oxidative stress indicator malondialdehyde (MDA), but there was no significant difference between the two groups. Pain intensity (measured by Visual Analogue Scale) and fatigue severity (measured by Fatigue Severity Scale) significantly decreased in the probiotic group compared to the placebo (p = 0.004 and p = 0.01, respectively). The probiotic group experienced significant improvement in some quality of life scales (measured by 36-Item Short Form Survey) and somatic and social dysfunction subscale of General Health Questionnaire scores compared to the placebo group (p = 0.01). The study suggests that the Saccharomyces boulardii probiotic supplement may benefit inflammatory markers, oxidative stress indicators, pain, fatigue, and quality of life in MS patients.

Natural polysaccharides protect against diet-induced obesity by improving lipid metabolism and regulating the immune system

Unhealthy dietary patterns-induced obesity and obesity-related complications pose a great threat to human health all over the world. Accumulating evidence suggests that the pathophysiology of obesity and obesity-associated metabolic disorders is closely associated with dysregulation of lipid and energy metabolism, and metabolic inflammation. In this review, three potential anti-obesity mechanisms of natural polysaccharides are introduced. Firstly, natural polysaccharides protect against diet-induced obesity directly by improving lipid and cholesterol metabolism. Since the immunity also affects lipid and energy metabolism, natural polysaccharides improve lipid and energy metabolism by regulating host immunity. Moreover, diet-induced mitochondrial dysfunction, prolonged endoplasmic reticulum stress, defective autophagy and microbial dysbiosis can disrupt lipid and/or energy metabolism in a direct and/or inflammation-induced manner. Therefore, natural polysaccharides also improve lipid and energy metabolism and suppress inflammation by alleviating mitochondrial dysfunction and endoplasmic reticulum stress, promoting autophagy and regulating gut microbiota composition. Specifically, this review comprehensively summarizes underlying anti-obesity mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates anti-obesity mechanisms of natural polysaccharides from the perspectives of their hypolipidemic, energy-regulating and immune-regulating mechanisms.

Unique Properties of Yeast Probiotic Saccharomyces boulardii CNCM I-745: A Narrative Review

Probiotics, both bacterial and yeast, have long been associated with a beneficial health history and human well-being. Among yeasts, Saccharomyces is a genus that is efficacious in rendering better human health, with Saccharomyces boulardii (S. boulardii) CNCM I-745 being classified as a probiotic agent. The present review highlights the unique properties of S. boulardii and its rolein the prevention of antibiotic-associated diarrhea (AAD) and pediatric acute gastroenteritis (PAGE) in comparison to bacterial probiotics. Its unique properties,such as viability over a wide pH range, inability to acquire antibiotic resistance genes, and property to achieve a steady state rapidly, have given S. boulardii an edge over bacterial probiotics. In AAD patients, prophylactic use of S. boulardii has shown a significantly lower risk of AAD (in comparison to controls) and restored the diversity of gut microbiota. Among Indian children with PAGE, S. boulardii CNCM I-745 was found superior to Lactobacillus rhamnosus GG and four strains of Bacillus clausii in shortening the duration of diarrhea and reducing the length of hospital stay. S. boulardii CNCM I-745 being considered a safe probiotic for use in children and adults also finds recommendations in several international guidelines for the management of acute diarrhea. The current review discusses evidence for the proven efficacy and safety of S. boulardii CNCM I-745 as a probiotic for preventing gastrointestinal disorders.

Evaluation of nutritional and physicochemical characteristics of soy yogurt by Lactobacillus plantarum KU985432 and Saccharomyces boulardii CNCMI-745

Nutritional yeast-produced soy yogurt has grown in demand, because of its unique nutritional and health benefits. It has low cholesterol, no lactose, and high levels of protein, probiotic yeast, vitamins, and minerals. In this work, Soymilk (12.5%) was prepared and fermented to produce soy yogurt. Growth curves, probiotic characteristics of Saccharomyces boulardii CNCMI-745 and Lactobacillus plantarum KU985432 were determined. The nutritional value of both yogurts was evaluated, including viable cell count, protein, vitamin B-complex, sugars, phenolic acids, and fatty acids, mineral content, stability, and storage. Analysis of the physicochemical composition of the yogurts included assessment of titratable acidity, antioxidant potential, viscosity, and moisture content. The probiotic viable count of the produced yogurts met the standards for commercial yogurts. S. boulardii CNCMI-745 displayed safety characteristics and high tolerance to heat, acid, and alkaline stress. The produced B vitamins increased in both yogurts. The total saturated fatty acids in Saccharomyces-yogurt decreased, while the unsaturated fatty acids increased. Saccharomyces-yogurt showed high antioxidant activity, phenolic acids, and crude protein content. Both yogurts demonstrated the same tendency for stability during 16 day-storage. In conclusion, using nutritional yeast in the production of soy yogurt increased its nutritional content more than probiotic lactic acid bacteria.

Exploring Extracellular Vesicles of Probiotic Yeast as Carriers of Biologically Active Molecules Transferred to Human Intestinal Cells

Extracellular vesicles (EVs) are nanoparticles containing various bioactive cargos-e.g., proteins, RNAs, and lipids-that are released into the environment by all cell types. They are involved in, amongst other functions, intercellular communication. This article presents studies on EVs produced by the probiotic yeast Saccharomyces boulardii CNCM I-745. The size distribution and concentration of EVs in the liquid culture of yeast were estimated. Moreover, the vesicles of S. boulardii were tested for their cytotoxicity against three model human intestinal cell lines. This study did not show any significant negative effect of yeast EVs on these cells under tested conditions. In addition, EVs of S. boulardii were verified for their ability to internalize in vitro with human cells and transfer their cargo. The yeast vesicles were loaded with doxorubicin, an anticancer agent, and added to the cellular cultures. Subsequently, microscopic observations revealed that these EVs transferred the compound to human intestinal cell lines. A cytotoxicity test confirmed the activity of the transferred doxorubicin. Detailed information about the proteins present in EVs might be important in terms of exploring yeast EVs as carriers of active molecules. Thus, proteomic analysis of the EV content was also conducted within the present study, and it allowed the identification of 541 proteins after matching them to the Saccharomyces Genome Database (SGD). Altogether, this study provides strong evidence that the EVs of the probiotic CNCM I-745 strain could be considered a drug delivery system.

Biocompatible smart micro/nanorobots for active gastrointestinal tract drug delivery

INTRODUCTION

Oral delivery is the most commonly used route of drug administration owing to good patient compliance. However, the gastrointestinal (GI) tract contains multiple physiological barriers that limit the absorption efficiency of conventional passive delivery systems resulting in a low drug concentration reaching the diseased sites. Micro/nanorobots can convert energy to self-propulsive force, providing a novel platform to actively overcome GI tract barriers for noninvasive drug delivery and treatment.

AREAS COVERED

In this review, we first describe the microenvironments and barriers in the different compartments of the GI tract. Afterward, the applications of micro/nanorobots to overcome GI tract barriers for active drug delivery are highlighted and discussed. Finally, we summarize and discuss the challenges and future prospects of micro/nanorobots for further clinical applications.

EXPERT OPINION

Micro/nanorobots with the ability to autonomously propel themselves and to load, transport, and release payloads on demand are ideal carriers for active oral drug delivery. Although there are many challenges to be addressed, micro/nanorobots have great potential to introduce a new era of drug delivery for precision therapy.

Comparative genomics of infective Saccharomyces cerevisiae strains reveals their food origin

Fungal infections are less studied than viral or bacterial infections and often more difficult to treat. Saccharomyces cerevisiae is usually identified as an innocuous human-friendly yeast; however, this yeast can be responsible for infections mainly in immunosuppressed individuals. S. cerevisiae is a relevant organism widely used in the food industry. Therefore, the study of food yeasts as the source of clinical infection is becoming a pivotal question for food safety. In this study, we demonstrate that S. cerevisiae strains cause infections to spread mostly from food environments. Phylogenetic analysis, genome structure analysis, and phenotypic characterization showed that the key sources of the infective strains are food products, such as bread and probiotic supplements. We observed that the adaptation to host infection can drive important phenotypic and genomic changes in these strains that could be good markers to determine the source of infection. These conclusions add pivotal evidence to reinforce the need for surveillance of food-related S. cerevisiae strains as potential opportunistic pathogens.

Inhibitory-like Substances Produced by Yeasts Isolated from Andean Blueberries: Prospective Food Antimicrobials

Natural agents from microorganisms have emerged as suitable options to replace chemical preservatives in foods. In this study, the antibacterial activity of cell-free supernatant (CFS) from five native yeasts (Saccharomyces cerevisiae Lev6 and Lev30, C. pseudointermedia Lev8, Candida intermedia Lev9, C. parapsilosis Lev15) and the reference S. boulardi SSB, was evaluated against some indicator food pathogens. The generation of antimicrobials was reliant on strain-, and sugar-supplemented media, which supported yeast growth established at 30 °C and 200 rpm for 48 h. Treatment with proteinase K and catalase was unable to completely abolish the inhibitory effect, indicating that the active components are likely complex combinations of acids, proteins, hydrogen peroxide, and other metabolites. Although there was no impact on Listeria monocytogenes, exposure to CFS and extracellular fractions obtained through precipitation with methanol (PPm) at 120 °C for 60 min significantly (p < 0.05) increased the inhibitory activity against Escherichia coli, Salmonella enterica, Kosakonia cowanii, and Staphylococcus aureus, indicating that the inhibitory activity was stimulated by heat. Likewise, a synergistic inhibitory action against Listeria was obtained following the pretreatment of PPm with EDTA (ethylenediaminetetraacetic acid). These activities were yeast strain-dependent, with Lev6, Lev8, and Lev30 showing the highest activity. In addition, a heat-stable low-molecular-mass molecule under 5 kDa was detected in Lev30. Further research is required to evaluate the mode of action and characterize the composition of the released molecules in the CFS in order to develop a novel biocontrol agent based on yeasts.

Novel yeasts with potential probiotic characteristics isolated from the endogenous ferment of artisanal Minas cheese

Artisanal Minas cheese (QMA) is traditionally elaborate using raw milk and endogenous ferment (pingo - whey or rala - grated ripened cheese). In the present study, 91 yeast strains were isolated and identified from pingo and rala. Eight yeast species were identified by the MALDI-TOF mass spectrometry and confirmed by sequencing of the ITS region. The yeasts' protease and lipase activities were evaluated in addition to probiotic properties such as tolerance to low pH and bile salts, hydrophobicity, autoaggregation, co-aggregation with pathogens, and antimicrobial susceptibility. The rala ferment showed a greater variety of species. Yarrowia lipolytica was the dominant specie (52.7% of isolates), followed by the Kluyveromyces lactis and Kodamaea ohmeri (9.9 and 6.6%, respectively). From the total yeasts evaluated, 74 strains showed positive enzymatic activity: 52 strains showed lipolytic (51 Y. lipolytica and one Trichosporon japonicum) and 44 proteolytic activities (18 Y. lipolytica, 13 K. ohmeri, 11 K. lactis, and 2 Wickerhamiella sp.). All evaluated isolates demonstrated tolerance to pH 2.0, and 69 isolates supported the presence of bile salts. From them, 12 isolates showed the capacity of autoaggregation (> 30%) and hydrophobicity (> 90.0%) and were then selected for co-aggregation and antibiotic resistance assays. All selected isolates showed co-aggregation with Salmonella Enteritidis, Escherichia coli, and Listeria monocytogenes greater than 30%. None of the yeast showed sensibility to the evaluated antibiotics and antagonistic activity against the evaluated pathogens. The results demonstrated that pingo and rala have different yeast composition with different enzymatic activity, which may affect the characteristics of the cheese. Furthermore, some yeast strains: Y. lipolytica (9 strains isolated from rala) and K. ohmeri (3 strains isolated from pingo) demonstrated attractive probiotic potential.

Recombinant hemagglutinin displaying on yeast reshapes congenital lymphocyte subsets to prompt optimized systemic immune protection against avian influenza infection

Introduction

Prophylactic vaccination is regarded as the most effective means to control avian flu infection. Currently, there is a need for a universal vaccine that provides broad and long-lasting protection against influenza virus. Meanwhile, although yeast-based vaccines have been used in clinic, studies are still required to further understand the molecular mechanism of yeast-based vaccines under physiological conditions.

Methods

We generated a yeast-based vaccine against influenza hemagglutinin (HA) of H5, H7 and H9 using surface displaying technology and evaluated the protective efficacy of chickens after exposure to H9N2 influenza virus.

Results

Oral yeast vaccine provided less clinical syndrome, reduced viral loading and alleviated airway damage significantly. Compared to the commercial inactivated vaccine, yeast vaccine stimulated the activation of splenic NK and APCs cells and boosted TLR7-IRF7-IFN signaling in spleen. Meanwhile, γδ T cells in the bursa of Fabricius were activated and the innate lymphoid cells (ILCs) in the bursa of Fabricius promoted the CILPs to differentiate to ILC3 cells in oral yeast birds. Moreover, the reshaped gut microbiota and a suppressed Th17-IL17-mediated inflammation in intestine was observed in oral yeast chickens, which might facilitate the recovery of intestinal mucosal immunity upon virus infection. Collectively, our findings suggest that oral yeast based multivalent bird flu vaccines provide an attractive strategy to update host defense function via reshapes of multi-systemic immune homeostasis.

Electrospinning and Electrospraying: Emerging Techniques for Probiotic Stabilization and Application

Probiotics are beneficial for human health. However, they are vulnerable to adverse effects during processing, storage, and passage through the gastrointestinal tract, thus reducing their viability. The exploration of strategies for probiotic stabilization is essential for application and function. Electrospinning and electrospraying, two electrohydrodynamic techniques with simple, mild, and versatile characteristics, have recently attracted increased interest for encapsulating and immobilizing probiotics to improve their survivability under harsh conditions and promoting high-viability delivery in the gastrointestinal tract. This review begins with a more detailed classification of electrospinning and electrospraying, especially dry electrospraying and wet electrospraying. The feasibility of electrospinning and electrospraying in the construction of probiotic carriers, as well as the efficacy of various formulations on the stabilization and colonic delivery of probiotics, are then discussed. Meanwhile, the current application of electrospun and electrosprayed probiotic formulations is introduced. Finally, the existing limitations and future opportunities for electrohydrodynamic techniques in probiotic stabilization are proposed and analyzed. This work comprehensively explains how electrospinning and electrospraying are used to stabilize probiotics, which may aid in their development in probiotic therapy and nutrition.

Analysis of the microbial content of probiotic products commercialized worldwide and survivability in conditions mimicking the human gut environment

Introduction

Probiotics are living microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Adequate number of living microbes, the presence of specific microorganisms, and their survival in the gastrointestinal (GI) environment are important to achieve desired health benefits of probiotic products. In this in vitro study, 21 leading probiotic formulations commercialized worldwide were evaluated for their microbial content and survivability in simulated GI conditions.

Methods

Plate-count method was used to determine the amount of living microbes contained in the products. Culture-dependent Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry and culture-independent metagenomic analysis through 16S and 18S rDNA sequencing were applied in combination for species identification. To estimate the potential survivability of the microorganisms contained in the products in the harsh GI environment, an in vitro model composed of different simulated gastric and intestinal fluids was adopted.

Results

The majority of the tested probiotic products were concordant with the labels in terms of number of viable microbes and contained probiotic species. However, one product included fewer viable microbes than those displayed on the label, one product contained two species that were not declared, and another product lacked one of the labeled probiotic strains. Survivability in simulated acidic and alkaline GI fluids was highly variable depending on the composition of the products. The microorganisms contained in four products survived in both acidic and alkaline environments. For one of these products, microorganisms also appeared to grow in the alkaline environment.

Conclusion

This in vitro study demonstrates that most globally commercialized probiotic products are consistent with the claims described on their labels with respect to the number and species of the contained microbes. Evaluated probiotics generally performed well in survivability tests, although viability of microbes in simulated gastric and intestinal environments showed large variability. Although the results obtained in this study indicate a good quality of the tested formulations, it is important to stress that stringent quality controls of probiotic products should always be performed to provide optimal health benefits for the host.

Current progress in the hypoglycemic mechanisms of natural polysaccharides

Unhealthy dietary pattern-induced type 2 diabetes mellitus poses a great threat to human health all over the world. Accumulating evidence has revealed that the pathophysiology of type 2 diabetes mellitus is closely associated with the dysregulation of glucose metabolism and energy metabolism, serious oxidative stress, prolonged endoplasmic reticulum stress, metabolic inflammation and intestinal microbial dysbiosis. Most important of all, insulin resistance and insulin deficiency are two key factors inducing type 2 diabetes mellitus. Nowadays, natural polysaccharides have gained increasing attention owing to their numerous health-promoting functions, such as hypoglycemic, energy-regulating, antioxidant, anti-inflammatory and prebiotic activities. Therefore, natural polysaccharides have been used to alleviate diet-induced type 2 diabetes mellitus. Specifically, this review comprehensively summarizes the underlying hypoglycemic mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates hypoglycemic mechanisms of natural polysaccharides from the perspectives of their regulatory effects on glucose metabolism, insulin resistance and mitochondrial dysfunction.

Postbiotics from Pichia kudriavzevii promote intestinal health performance through regulation of Limosilactobacillus reuteri in weaned piglets

Postbiotics are attractive as alternatives to antibiotics for use against post-weaning diarrhea. However, their beneficial mechanisms are largely unknown. In the current study, we first demonstrated that supplementation with 0.5% Pichia kudriavzevii FZ12 postbiotics in the diet significantly reduced diarrhea incidence, promoted growth performance, improved gut health performance, and significantly enriched beneficial bacteria, particularly Lactobacillus spp., in the intestines of weaned piglets. Importantly, we identified a heat- and proteinase K-sensitive component, cytochrome c, of the postbiotics that significantly promoted the growth and biofilm formation of Limosilactobacillus reuteri FP13. We demonstrated the importance of P. kudriavzevii FZ12 postbiotics in improving the intestinal health of a model animal and revealed that cytochrome c is one of the important components of yeast postbiotics. These findings may provide new insights into microbe-postbiotics interplay that can be applied to guidelines for dietary modulation to alleviate weaning-induced diarrhea.

Twin-bioengine self-adaptive micro/nanorobots using enzyme actuation and macrophage relay for gastrointestinal inflammation therapy

A wide array of biocompatible micro/nanorobots are designed for targeted drug delivery and precision therapy largely depending on their self-adaptive ability overcoming complex barriers in vivo. Here, we report a twin-bioengine yeast micro/nanorobot (TBY-robot) with self-propelling and self-adaptive capabilities that can autonomously navigate to inflamed sites for gastrointestinal inflammation therapy via enzyme-macrophage switching (EMS). Asymmetrical TBY-robots effectively penetrated the mucus barrier and notably enhanced their intestinal retention using a dual enzyme-driven engine toward enteral glucose gradient. Thereafter, the TBY-robot was transferred to Peyer's patch, where the enzyme-driven engine switched in situ to macrophage bioengine and was subsequently relayed to inflamed sites along a chemokine gradient. Encouragingly, EMS-based delivery increased drug accumulation at the diseased site by approximately 1000-fold, markedly attenuating inflammation and ameliorating disease pathology in mouse models of colitis and gastric ulcers. These self-adaptive TBY-robots represent a safe and promising strategy for the precision treatment of gastrointestinal inflammation and other inflammatory diseases.

Non-saccharomyces yeast probiotics: revealing relevance and potential

Non-Saccharomyces yeasts are unicellular eukaryotes that play important roles in diverse ecological niches. In recent decades, their physiological and morphological properties have been reevaluated and reassessed, demonstrating the enormous potential they possess in various fields of application. Non-Saccharomyces yeasts have gained relevance as probiotics, and in vitro and in vivo assays are very promising and offer a research niche with novel applications within the functional food and nutraceutical industry. Several beneficial effects have been described, such as antimicrobial and antioxidant activities and gastrointestinal modulation and regulation functions. In addition, several positive effects of bioactive compounds or production of specific enzymes have been reported on physical, mental and neurodegenerative diseases as well as on the organoleptic properties of the final product. Other points to highlight are the multiomics as a tool to enhance characteristics of interest within the industry; as well as microencapsulation offer a wide field of study that opens the niche of food matrices as carriers of probiotics; in turn, non-Saccharomyces yeasts offer an interesting alternative as microencapsulating cells of various compounds of interest.

Fungal feelings in the irritable bowel syndrome: the intestinal mycobiome and abdominal pain

Although the gut microbiota consists of bacteria, viruses, and fungi, most publications addressing the microbiota-gut-brain axis in irritable bowel syndrome (IBS) have a sole focus on bacteria. This may relate to the relatively low presence of fungi and viruses as compared to bacteria. Yet, in the field of inflammatory bowel disease research, the publication of several papers addressing the role of the intestinal mycobiome now suggested that these low numbers do not necessarily translate to irrelevance. In this review, we discuss the available clinical and preclinical IBS mycobiome data, and speculate how these recent findings may relate to earlier observations in IBS. By surveying literature from the broader mycobiome research field, we identified questions open to future IBS-oriented investigations.

Probiotic Debaryomyces hansenii CBS 8339 yeast enhanced immune responses in mice

This study aimed to examine the effect of Debaryomyces hansenii CBS 8339 on innate immune responses in mice. Thirty BALB/c mice were randomly treated with phosphate buffered saline (PBS) (control) and two D. hansenii (Dh) doses: Dh 10ˆ6 CFU (colony forming units) and Dh 10ˆ8 CFU daily for 15 days. Spleen, blood, and gut samples were taken on days 7 and 15. Mouse splenocytes were isolated and challenged with Escherichia coli. Immunological assays and immune-related gene expressions were performed. Serum was obtained from blood for total IgA and IgG antibody titer determination. Gut samples were taken for yeast colonization assessment. Phagocytosis, respiratory burst activity, and nitric oxide production in mice were mainly enhanced (p < 0.05) upon 7 days of D. hansenii intake at a concentration of 10ˆ8 CFU before and after bacterial challenge. Moreover, oral D. hansenii in mice upregulated (p < 0.05) gene expression of pro-inflammatory cytokines (INF-γ, IL-6 and IL-1β) before or after E. coli challenge on day 7 but downregulated (p < 0.05) on day 15. Furthermore, total serum IgG and IgA titers were higher (p < 0.05) in Dh 10ˆ8 CFU at days 7 and 15, and only at day 7, respectively, than that in the other dose and control groups. Finally, D. hansenii was detected in the gut of mice that received the treatments, suggesting that yeast survived gastrointestinal transit. Altogether, a short period (7 days) of D. hansenii CBS 8339 oral delivery improved immune innate response on mice.

Probiotics to improve the gut microbiome in premature infants: are we there yet?

Gut microbiome maturation in infants born prematurely is uniquely influenced by the physiological, clinical, and environmental factors surrounding preterm birth and early life, leading to altered patterns of microbial succession relative to term infants during the first months of life. These differences in microbiome composition are implicated in acute clinical conditions that disproportionately affect preterm infants, including necrotizing enterocolitis (NEC) and late-onset sepsis (LOS). Probiotic supplementation initiated early in life is an effective prophylactic measure for preventing NEC, LOS, and other clinical concerns relevant to preterm infants. In parallel, reported benefits of probiotics on the preterm gut microbiome, metabolome, and immune function are beginning to emerge. This review summarizes the current literature on the influence of probiotics on the gut microbiome of preterm infants, outlines potential mechanisms by which these effects are exerted, and highlights important clinical considerations for determining the best practices for probiotic use in premature infants.

In vitro assessment of probiotic attributes for strains contained in commercial formulations

Although probiotics are often indiscriminately prescribed, they are not equal and their effects on the host may profoundly differ. In vitro determination of the attributes of probiotics should be a primary concern and be performed even before clinical studies are designed. In fact, knowledge on the biological properties a microbe possesses is crucial for selecting the most suitable bacteriotherapy for each individual. Herein, nine strains (Bacillus clausii NR, OC, SIN, T, Bacillus coagulans ATCC 7050, Bifidobacterium breve DSM 16604, Limosilactobacillus reuteri DSM 17938, Lacticaseibacillus rhamnosus ATCC 53103, and Saccharomyces boulardii CNCM I-745) declared to be contained in six commercial formulations were tested for their ability to tolerate simulated intestinal conditions, adhere to mucins, and produce β-galactosidase, antioxidant enzymes, riboflavin, and D-lactate. With the exception of B. breve, all microbes survived in simulated intestinal fluid. L. rhamnosus was unable to adhere to mucins and differences in mucin adhesion were evidenced for L. reuteri and S. boulardii depending on oxygen levels. All microorganisms produced antioxidant enzymes, but only B. clausii, B. coagulans, B. breve, and L. reuteri synthesize β-galactosidase. Riboflavin secretion was observed for Bacillus species and L. rhamnosus, while D-lactate production was restricted to L. reuteri and L. rhamnosus. Our findings indicate that the analyzed strains possess different in vitro biological properties, thus highlighting the usefulness of in vitro tests as prelude for clinical research.

The gut mycobiome in health, disease, and clinical applications in association with the gut bacterial microbiome assembly

The gut mycobiome (fungi) is a small but crucial component of the gut microbiome in humans. Intestinal fungi regulate host homoeostasis, pathophysiological and physiological processes, and the assembly of the co-residing gut bacterial microbiome. Over the past decade, accumulating studies have characterised the gut mycobiome in health and several pathological conditions. We review the compositional and functional diversity of the gut mycobiome in healthy populations from birth to adulthood. We describe factors influencing the gut mycobiome and the roles of intestinal fungi-especially Candida and Saccharomyces spp-in diseases and therapies with a particular focus on their synergism with the gut bacterial microbiome and host immunity. Finally, we discuss the underappreciated effects of gut fungi in clinical implications, and highlight future microbiome-based therapies that harness the tripartite relationship among the gut mycobiome, bacterial microbiome, and host immunity, aiming to restore a core gut mycobiome and microbiome and to improve clinical efficacy.

Co-Expression of Pig IL-2 and Fusion Bovine Cathelicidin Gene by Recombinant Plasmids in Yeast and Their Promotion of Mouse Antibacterial Defense

In order to develop an effective and safe immunomodulator to enhance the antimicrobial bioactivity and immunity of animals against infectious bacterial diseases, a recombinant plasmid pGAPZαA-IL2-B co-expressing pig interleukin-2 (PIL-2) and fused bovine cathelicidin (FBC) genes were constructed using the 2A self-cleavage technique. After being expressed in Pichia pastoris strain SMD1168, the recombinant yeast was administered orally to 5-week-old female ICR mice. The control mice were similarly dosed with P. pastoris with a blank plasmid or FBC recombinant plasmid alone. At 28 days post-treatment, the mice were challenged intraperitoneally with virulent strains of either E. coli or S. aureus. Compared with the control groups, the mice that received recombinant yeast co-expressing PIL-2/FBC manifested significant increases in the number of leukocytes, CD4+ and CD8+ T cells, IgG, and the gene expressions of TLRs(TLR1,4,6,9), antimicrobial peptides(CRP4 and CRAMP) and cytokines (IL-2, 4, 6, 7, 12, 15, 23, IFN-γ, and TNF-α) in the blood. Furthermore, the treated mice displayed significantly higher survival than the other two control groups after the challenge. These results suggest that the antimicrobial activity and immunity of animals can be effectively enhanced by the in vivo co-expression of IL-2 and the FBS gene, which can facilitate the development of new immunopotentiation molecules to overcome the infection of antibiotic-resistant bacteria.

In vitro evaluation of probiotic potential and enzymatic profiling of Pichia kudriavzevii Y33 isolated from traditional home-made mango pickle

Background

Fermented foods are the results of metabolic activities of various microorganisms. People have traditionally known how to culture desirable microorganisms, primarily lactic acid bacteria, yeasts, and filamentous molds, for the manufacture of edible foods. Yeast isolated from home-made mango pickle from Hamirpur, Himachal Pradesh, was assessed for probiotic properties and their enzymatic profiling.

Results

Four yeast isolates were isolated out of which P. kudriavzevii Y33 was selected on the basis of high acid tolerance as well as broadest antimicrobial activity. The selected isolate was observed to have high acid tolerance at pH 2 and show strong antimicrobial activity against all the pathogens examined. P. kudriavzevii Y33 can also withstand high bile concentration and showed high viability index, i.e., 95% at concentration of 2% of bile. The isolate was able to demonstrate high cholesterol assimilation in medium containing ox bile and taurocholate, at 88.58 and 86.83%, respectively. The autoaggregation ability of isolate increases with increasing the time of incubation and showed 87% of autoaggregation after 24 h of incubation. P. kudriavzevii Y33 exhibited resistance towards different antibiotics, found to be positive for exopolysaccharide production and showed no hemolytic activity. The isolate was observed to produce several enzymes such as β-galactosidase, protease, amylase, phytase, and lipase.

Conclusions

The results of the current study revealed that P. kudriavzevii Y33 has various beneficial qualities that suggest it could be used as probiotics. Enzymes produced by yeast isolate help in improving flavor and mineral availability in the fermented products.

ProbResist: a database for drug-resistant probiotic bacteria

Drug resistance remains a global threat, and the rising trend of consuming probiotic-containing foods, many of which harbor antibiotic resistant determinants, has raised serious health concerns. Currently, the lack of accessibility to location-, drug- and species-specific information of drug-resistant probiotics has hampered efforts to combat the global spread of drug resistance. Here, we describe the development of ProbResist, which is a manually curated online database that catalogs reports of probiotic bacteria that have been experimentally proven to be resistant to antibiotics. ProbResist allows users to search for information of drug resistance in probiotics by querying with the names of the bacteria, antibiotic or location. Retrieved results are presented in a downloadable table format containing the names of the antibiotic, probiotic species, resistant determinants, region where the study was conducted and digital article identifiers (PubMed Identifier and Digital Object Identifier) hyperlinked to the original sources. The webserver also presents a simple analysis of information stored in the database. Given the increasing reports of drug-resistant probiotics, an exclusive database is necessary to catalog them in one platform. It will enable medical practitioners and experts involved in policy making to access this information quickly and conveniently, thus contributing toward the broader goal of combating drug resistance.

Opportunities and challenges for synthetic biology in the therapy of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a complex, chronic intestinal inflammatory disorder that primarily includes Crohn’s disease (CD) and ulcerative colitis (UC). Although traditional antibiotics and immunosuppressants are known as the most effective and commonly used treatments, some limitations may be expected, such as limited efficacy in a small number of patients and gut flora disruption. A great many research studies have been done with respect to the etiology of IBD, while the composition of the gut microbiota is suggested as one of the most influential factors. Along with the development of synthetic biology and the continuing clarification of IBD etiology, broader prospects for novel approaches to IBD therapy could be obtained. This study presents an overview of the currently existing treatment options and possible therapeutic targets at the preclinical stage with respect to microbial synthesis technology in biological therapy. This study is highly correlated to the following topics: microbiota-derived metabolites, microRNAs, cell therapy, calreticulin, live biotherapeutic products (LBP), fecal microbiota transplantation (FMT), bacteriophages, engineered bacteria, and their functional secreted synthetic products for IBD medical implementation. Considering microorganisms as the main therapeutic component, as a result, the related clinical trial stability, effectiveness, and safety analysis may be the major challenges for upcoming research. This article strives to provide pharmaceutical researchers and developers with the most up-to-date information for adjuvant medicinal therapies based on synthetic biology.

Genomic features, aroma profiles, and probiotic potential of the Debaryomyces hansenii species complex strains isolated from Korean soybean fermented food

Fermented soybean products are gaining attention in the food industry owing to their nutritive value and health benefits. In this study, we performed genomic analysis and physiological characterization of two Debaryomyces spp. yeast isolates obtained from a Korean traditional fermented soy sauce "ganjang". Both Debaryomyces hansenii ganjang isolates KD2 and C11 showed halotolerance to concentrations of up to 15% NaCl and improved growth in the presence of salt. Ploidy and whole-genome sequencing analyses indicated that the KD2 genome is haploid, whereas the C11 genome is heterozygous diploid with two distinctive subgenomes. Interestingly, phylogenetic analysis using intron sequences indicated that the C11 strain was generated via hybridization between D. hansenii and D. tyrocola ancestor strains. The D. hansenii KD2 and D. hansenii-hybrid C11 produced various volatile flavor compounds associated with butter, caramel, cheese, and fruits, and showed high bioconversion activity from ferulic acid to 4-vinylguaiacol, a characteristic flavor compound of soybean products. Both KD2 and C11 exhibited viability in the presence of bile salts and at low pH and showed immunomodulatory activity to induce high levels of the anti-inflammatory cytokine IL-10. The safety of the yeast isolates was confirmed by analyzing virulence and acute oral toxicity. Together, the D. hansenii ganjang isolates possess physiological properties beneficial for improving the flavor and nutritional value of fermented products.

The development of live biotherapeutics against Clostridioides difficile infection towards reconstituting gut microbiota

Clostridioides difficile is the most prevalent pathogen of nosocomial diarrhea. In the United States, over 450,000 cases of C. difficile infection (CDI), responsible for more than 29,000 deaths, are reported annually in recent years. Because of the emergence of hypervirulent strains and strains less susceptible to vancomycin and fidaxomicin, new therapeutics other than antibiotics are urgently needed. The gut microbiome serves as one of the first-line defenses against C. difficile colonization. The use of antibiotics causes gut microbiota dysbiosis and shifts the status from colonization resistance to infection. Hence, novel CDI biotherapeutics capable of reconstituting normal gut microbiota have become a focus of drug development in this field.

Assessment of Yeasts as Potential Probiotics: A Review of Gastrointestinal Tract Conditions and Investigation Methods

Probiotics are microorganisms (including bacteria, yeasts and moulds) that confer various health benefits to the host, when consumed in sufficient amounts. Food products containing probiotics, called functional foods, have several health-promoting and therapeutic benefits. The significant role of yeasts in producing functional foods with promoted health benefits is well documented. Hence, there is considerable interest in isolating new yeasts as potential probiotics. Survival in the gastrointestinal tract (GIT), salt tolerance and adherence to epithelial cells are preconditions to classify such microorganisms as probiotics. Clear understanding of how yeasts can overcome GIT and salt stresses and the conditions that support yeasts to grow under such conditions is paramount for identifying, characterising and selecting probiotic yeast strains. This study elaborated the adaptations and mechanisms underlying the survival of probiotic yeasts under GIT and salt stresses. This study also discussed the capability of yeasts to adhere to epithelial cells (hydrophobicity and autoaggregation) and shed light on in vitro methods used to assess the probiotic characteristics of newly isolated yeasts.

Consumer's acceptability and health consciousness of probiotic and prebiotic of non-dairy products

Human gut microbiota is a protective agent of intestinal and systemic health, and its modulation is of great interest for human wellbeing. In the world of biotics, besides probiotics, prebiotics, and synbiotics, also appears the denomination of "postbiotics" and "psychobiotics". Fermented dairy products are, traditionally, the major source of probiotics. Nevertheless, due to the increasing number of lactose-intolerant individuals and strict vegetarians, there is a need for innovative non-dairy products. Non-dairy biotics are being included in the normal diet and due to technological advances, many products are created using non-conventional food matrices like kombucha tea, herbal tea, baking mix, and cereal-based products. The microorganisms most used as probiotics in many of the non-dairy products are strains belonging to the genera Bifidobacterium, Enterococcus, Lactobacillus, Lactococcus, Streptococcus, and Bacillus, and some yeast strains namely Saccharomyces cerevisiae var. boulardii. Recently, several other yeasts have been described as having probiotic properties. This review describes gut-derived effects in humans of possible microorganisms, such as yeasts, and bacteria, isolated from non-dairy fermented and non-fermented foods and beverages. The microorganisms responsible for the processing of these non-dairy fermented products, together with the prebiotics, form a class of nutrients that have been proven to be beneficial for our gut health.

Therapeutic potential of Saccharomyces boulardii in liver diseases: from passive bystander to protective performer?

Saccharomyces boulardii (S. boulardii) is a probiotic yeast that has been elucidated to be efficacious in fighting various gastrointestinal diseases in preclinical as well as clinical studies. Its general mechanisms of probiotic action in the treatment of gastrointestinal conditions cover multifaceted aspects, including immune regulation, production of antimicrobial substances, pathogen competitive elimination, gut barrier integrity maintenance, intestinal trophic effect and antioxidant potency. In this review, basic knowledge with regard to the gut-liver axis, available probiotics remedies and mechanistic insights of S. boulardii as probiotics will be elucidated. In addition, we summarize the therapeutic potential of S. boulardii in several liver diseases evident from both bench and bedside information, such as acute liver injury/failure, fibrosis, hepatic damages due to metabolic disturbance or infection and obstructive jaundice. Future prospects in relation to medicinal effects of S. boulardii are also exploited and discussed on the basis of novel and attractive therapeutic concept in the latest scientific literature.

The Flo Adhesin Family

The first step in the infection of fungal pathogens in humans is the adhesion of the pathogen to host tissue cells or abiotic surfaces such as catheters and implants. One of the main players involved in this are the expressed cell wall adhesins. Here, we review the Flo adhesin family and their involvement in the adhesion of these yeasts during human infections. Firstly, we redefined the Flo adhesin family based on the domain architectures that are present in the Flo adhesins and their functions, and set up a new classification of Flo adhesins. Next, the structure, function, and adhesion mechanisms of the Flo adhesins whose structure has been solved are discussed in detail. Finally, we identified from Pfam database datamining yeasts that could express Flo adhesins and are encountered in human infections and their adhesin architectures. These yeasts are discussed in relation to their adhesion characteristics and involvement in infections.

Probiotics and Trained Immunity

The characteristics of innate immunity have recently been investigated in depth in several research articles, and original findings suggest that innate immunity also has a memory capacity, which has been named “trained immunity”. This notion has revolutionized our knowledge of the innate immune response. Thus, stimulation of trained immunity represents a therapeutic alternative that is worth exploring. In this context, probiotics, live microorganisms which when administered in adequate amounts confer a health benefit on the host, represent attractive candidates for the stimulation of trained immunity; however, although numerous studies have documented the beneficial proprieties of these microorganisms, their mechanisms of action are not yet fully understood. In this review, we propose to explore the putative connection between probiotics and stimulation of trained immunity.