Comparison of functional characteristics of distinct Saccharomyces boulardii strains isolated from commercial food supplements

Probiotic Properties and Safety Evaluation in the Invertebrate Model Host Galleria mellonella of the Pichia kudriavzevii YGM091 Strain Isolated from Fermented Goat Milk

Potential probiotic yeast strains isolated from fermented food need to meet safe and beneficial conditions for the host's health. The Pichia kudriavzevii YGM091 strain isolated from fermented goat milk has outstanding probiotic characteristics, including: the high survival percentage in digestive system conditions (reaching up 247.13 ± 0.12 and 145.03 ± 0.06% at pH 3.0 and bile salt 0.5%, respectively); good tolerance to temperature, salt, phenol, ethanol; good surface properties such as high hydrophobicity percentage (> 60%), the high auto-aggregation percentage rate (66.56 ± 1.45% after 45 min of incubation) and the high co-aggregation percentage rate with pathogenic bacteria in a short time (> 40% after 2 h of incubation); biofilm forming after 24 h of incubation on abiotic surfaces; antioxidant activity reached excellent level after only 24 h of incubation (The percentage free radical scavenging and the Trolox equivalent reaching up 79.86 ± 0.70% and 92.09 ± 0.75 µg/mL after 72 h of incubation); extracellular enzymes production protease and cellulase with high activity, amylase and pectinase with moderate activity and non-lipase activity. Simultaneously, the YGM091 strain is the in vitro safety yeast: insensitive to antibiotics and fluconazole, negative for gelatinase, phospholipase, coagulase, and non-hemolysis activities. Furthermore, this strain is in vivo safety yeast with the dosages below 106 CFU/larva in the Galleria mellonella model with over 90% survival larvae and the yeast density reduced to just 102-103 CFU/larva after 72 h post-injection. Research results have demonstrated that the Pichia kudriavzevii YGM091 strain is a safe potential probiotic yeast and could become a candidate probiotic food to be used in the future.

Enhanced Production of β-Nicotinamide Mononucleotide with Exogenous Nicotinamide Addition in Saccharomyces boulardii-YS01

β-Nicotinamide mononucleotide (NMN), as a key precursor of an essential coenzyme nicotinamide adenine dinucleotide (NAD+), is most recognized for its pathological treatment effects and anti-aging functions. Here, the biosynthesis of NMN from the inexpensive feedstock substrate nicotinamide (Nam) using previously isolated Saccharomyces boulardii-YS01 was investigated. Ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UPLC-ESI-QqQ-MS/MS) was established for the determination and targeted analysis of NMN, nicotinamide riboside (NR), nicotinic acid (NA), Nam, and NAD+ in YS01 cells. Satisfactory precision and accuracy values were achieved with recoveries above 70% for five analytes. A 5~100 times higher content of NMN in YS01 (0.24~103.40 mg/kg) than in some common foods (0.0~18.8 mg/kg) was found. Combined with genome sequencing and enzyme function annotation, target-acting enzymes, including nudC, ISN1, URH1, PNP, and SIR2, were identified, and the biosynthetic pathway of NMN via Nam was suggested. The initial addition of 3 g/L Nam in the culture medium effectively promoted the generation of NMN, which raised the content of NMN by 39%. This work supplements an alternative resource for NMN production and lays the theoretical foundation for the further construction of NMN transgenic synthesis hosts.

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.

Effects of fungal based bioactive compounds on human health: Review paper

Since the first years of history, microbial fermentation products such as bread, wine, yogurt and vinegar have always been noteworthy regarding their nutritional and health effects. Similarly, mushrooms have been a valuable food product in point of both nutrition and medicine due to their rich chemical components. Alternatively, filamentous fungi, which can be easier to produce, play an active role in the synthesis of some bioactive compounds, which are also important for health, as well as being rich in protein content. Therefore, this review presents some important bioactive compounds (bioactive peptides, chitin/chitosan, β-glucan, gamma-aminobutyric acid, L-carnitine, ergosterol and fructooligosaccharides) synthesized by fungal strains and their health benefits. In addition, potential probiotic- and prebiotic fungi were researched to determine their effects on gut microbiota. The current uses of fungal based bioactive compounds for cancer treatment were also discussed. The use of fungal strains in the food industry, especially to develop innovative food production, has been seen as promising microorganisms in obtaining healthy and nutritious food.

The Probiotic Effects of the Saccharomyces cerevisiae 28-7 Strain Isolated from Nuruk in a DSS-Induced Colitis Mouse Model

Probiotics are microorganisms that can benefit host health when ingested in a live state, and lactic acid bacteria are the most common type. Among fungi, Saccharomyces boulardii (SB) is the only strain known to have a probiotic function with beneficial effects on colitis; however, information on other probiotic yeast strains is limited. Therefore, this study aimed to discover yeast strains expressing intestinal anti-inflammatory activities by exhibiting probiotic properties in dextran sodium sulfate (DSS)-induced colitis mice model. Nuruk (Korean traditional fermentation starter) containing various microbial strains was used as a source for yeast strains, and S. cerevisiae 28-7 (SC28-7) strain was selected with in vitro and in vivo characteristics to enable survival in the intestines. After 14 days of pretreatment with the yeast strains, DSS was co-administered for six days to induce colitis in mice. The results revealed that the disease activity index score was lowered by SC28-7 treatment compared to the DSS group, and the colon length and weight/length ratio were recovered in a pattern similar to that of the normal group. SC28-7 administration significantly reduced the secretion of pro-inflammatory cytokines in the serum and modified the mRNA expression of inflammatory cytokines (interleukin-1β, transforming growth factor-β, and interferon-γ) and proteins involved in gut barrier functions (mucin 2, mucin 3, zonula occludens-1, and occludin) in colon tissues. These results indicate that SC28-7 attenuates DSS-induced colon damage and inflammation, supporting its future use as a probiotic yeast for treating and preventing intestinal inflammatory diseases such as inflammatory bowel disease.

Unique Probiotic Properties and Bioactive Metabolites of Saccharomyces boulardii

Saccharomyces boulardii (S. boulardii) is a probiotic and is widely used to improve the nutritional and functional value of food. This study aimed to compare the probiotic properties of S. boulardii and Saccharomyces cerevisiae. A series of in vitro probiotic experiments was performed, including simulated gastrointestinal digestion, bile salt tolerance, hydrophobicity, self-aggregation, and antioxidant and antibacterial properties. Self-aggregation and hydrophobic properties of S. boulardii were relatively poor, but they showed high tolerance, antioxidant properties, and broad antibacterial properties. In addition, non-targeted metabolomics was used to comprehensively analyze the active metabolites of S. boulardii and the metabolic differences between S. boulardii and S. cerevisiae were compared. Saccharomyces boulardii produced many bioactive metabolites, which generally showed antioxidant, antibacterial, antitumor, anti-inflammatory, and other properties. In contrast to S. cerevisiae, S. boulardii produced phenyllactic acid and 2-hydroxyisocaproic acid. There were also significant differences in their metabolic pathways. These results may be of great significance in the medical and food industries and provide a basis for understanding the metabolism of S. boulardii. It also shows that metabolomics is an effective and novel method for screening microbial functional metabolites and identifying functional differences between similar microorganisms.

In Vitro Characterization and Identification of Potential Probiotic Yeasts Isolated from Fermented Dairy and Non-Dairy Food Products

This study is about the isolation of yeast from fermented dairy and non-dairy products as well as the characterization of their survival in in vitro digestion conditions and tolerance to bile salts. Promising strains were selected to further investigate their probiotic properties, including cell surface properties (autoaggregation, hydrophobicity and coaggregation), physiological properties (adhesion to the HT-29 cell line and cholesterol lowering), antimicrobial activities, bile salt hydrolysis, exopolysaccharide (EPS) producing capability, heat resistance and resistance to six antibiotics. The selected yeast isolates demonstrated remarkable survivability in an acidic environment. The reduction caused by in vitro digestion conditions ranged from 0.7 to 2.1 Log₁₀. Bile salt tolerance increased with the extension in the incubation period, which ranged from 69.2% to 91.1% after 24 h. The ability of the 12 selected isolates to remove cholesterol varied from 41.6% to 96.5%, and all yeast strains exhibited a capability to hydrolyse screened bile salts. All the selected isolates exhibited heat resistance, hydrophobicity, strong coaggregation, autoaggregation after 24 h, robust antimicrobial activity and EPS production. The ability to adhere to the HT-29 cell line was within an average of 6.3 Log₁₀ CFU/mL after 2 h. Based on ITS/5.8S ribosomal DNA sequencing, 12 yeast isolates were identified as 1 strain for each Candidaalbicans and Saccharomyces cerevisiae and 10 strains for Pichia kudriavzevii.

Effects of Live Combined Bacillus subtilis and Enterococcus faecium on Gut Microbiota Composition in C57BL/6 Mice and in Humans

Probiotics, prebiotics, and synbiotics can alleviate metabolic syndrome by altering the composition of the gut microbiota. Live combined Enterococcus faecium and Bacillus subtilis has been indicated to promote growth and reduce inflammation in animal models. However, the modulatory effects of live combined B. subtilis R-179 and E. faecium R-026 (LCBE) on human microbiota remain unclear. The current study examined the growth of these two strains in the presence of various oligosaccharides and assessed the effects of this probiotic mixture on human and murine gut microbiota in vitro and in vivo. Oligosaccharides improved the growth of E. faecium R-026 and B. subtilis R-179 as well as increased their production of short-chain fatty acids. E. faecium R-026 or B. subtilis R-179 co-incubated with Bifidobacterium and Clostridium significantly increased the number of the anaerobic bacteria Bifidobacterium longum and Clostridium butyricum by in vitro fermentation. Moreover, LCBE significantly reduced plasma cholesterol levels in mouse models of hyperlipidemia. LCBE combined with galacto-oligosaccharides led to a significant decrease in the Firmicutes/Bacteroidetes ratio and a significant increase in the relative abundance of Akkermansia and Bifidobacteria after treating mice with LCBE (0.23 g/day) for eight weeks. Furthermore, in vitro fermentation also showed that both the single strains and the two-strain mixture modulated human gut microbiota, resulting in increased Lactobacillus and Bifidobacteria, and decreased Escherichia-Shigella. Overall, these results suggest that LCBE can improve host health by reducing the level of cholesterol in mouse models by modifying the composition of the gut microbiota.

Investigation of probiotic potential of yeasts isolated from sourdoughs from different regions of Turkey

In this study, 14 yeast cultures from 62 isolates from traditional sourdoughs collected from 6 different regions of Turkey were selected by FT-IR identification and characterised to reveal their probiotic properties. Four yeast strains were genotypically identified and compared with FT-IR identification. In all analyses, it was observed that mostly Saccaromyces cerevisiae strain exhibited high hydrophobicity, auto-aggregation feature, and all yeast isolates in this study showed tolerance to 0.3%, even salt concentration. In addition, all yeast strains were susceptible to anti-yeasts agents, although they were resistant to all antibiotics used in the study. All selected yeast isolates exhibited high antimicrobial activity against the Staphylococcus aureus. In conclusion, this study investigated the potential probiotic properties of yeast strains isolated from sourdough.

Probiotic and Potentially Probiotic Yeasts-Characteristics and Food Application

Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. Besides the well-known and tested lactic acid bacteria, yeasts may also be probiotics. The subject of probiotic and potentially probiotic yeasts has been developing and arising potential for new probiotic products with novel properties, which are not offered by bacteria-based probiotics available on the current market. The paper reviews the first probiotic yeast Saccharomyces cerevisiae var. boulardii, its characteristics, pro-healthy activities and application in functional food production. This species offers such abilities as improving digestion of certain food ingredients, antimicrobial activities and even therapeutic properties. Besides Saccharomyces cerevisiae var. boulardii, on this background, novel yeasts with potentially probiotic features are presented. They have been intensively investigated for the last decade and some species have been observed to possess probiotic characteristics and abilities. There are yeasts from the genera Debaryomyces, Hanseniaspora, Pichia, Meyerozyma, Torulaspora, etc. isolated from food and environmental habitats. These potentially probiotic yeasts can be used for production of various fermented foods, enhancing its nutritional and sensory properties. Because of the intensively developing research on probiotic yeasts in the coming years, we can expect many discoveries and possibly even evolution in the segment of probiotics available on the market.