Characterization of yeasts isolated from traditional kefir grains for potential probiotic properties

In vitro fermentation characteristics of dietary fibers using fecal inoculum from dogs consuming commercial or grain kefir

Traditional grain kefir is produced from the fermentation of milk with yeast- and bacteria-containing cultures. To maintain consistency and adhere to food safety guidelines, commercial kefir products are based on starter bacterial cultures. Bacterial profiles of starter vs. grain kefirs differ, and their influence on health effects is unknown. Our objectives were to determine the in vitro fermentation characteristics of common dietary fibers using fecal inoculum from dogs supplemented with kefir or kefir bacterial culture as inoculum. Healthy adult dogs were allotted to one of 3 treatments and supplemented for 14 d (n = 4/treatment): 1) 2% reduced-fat milk treated with lactase (CNTL), 2) starter kefir (S-Kefir), or 3) grain kefir (G-Kefir). After 14 d, fresh fecal samples were collected and frozen in a 20% glycerol solution. For the in vitro experiment, fecal samples were thawed, diluted in an anaerobic diluting solution, and used to inoculate tubes containing semi-defined medium and either cellulose (CEL), pectin (PC), beet pulp (BP), or chicory pulp (CP). Tubes were incubated for 0, 6, 12, or 18 h, with short-chain fatty acids (SCFA), pH, and microbiota measured at each time point. A second in vitro experiment was conducted using similar methods and measurements but with S-Kefir and G-Kefir as inoculum sources. Effects of treatment (inoculum), time, and treatment*time interactions within the fiber source were analyzed statistically using Mixed Models and repeated measures, with P < 0.05 being significant. Using fecal inoculum, BP and PC were rapidly fermented, leading to large pH reductions, SCFA increases, and microbiota shifts. pH change was of greater (P < 0.05) magnitude (PC) and higher (P < 0.05) kinetic rate (CP) when using feces from dogs fed S-Kefir or G-Kefir than controls. Butyrate increases were greater (P < 0.05) in tubes inoculated with G-Kefir feces than in S-Kefir or control feces. When PC and BP were fermented, tubes with S-Kefir feces had greater (P < 0.05) acetate, propionate, and total SCFA increases than G-Kefir or control feces. Fermentations were slower when using kefir cultures as inoculum, but some differences were noted. Bacterial beta diversity and relative abundances shifted over time within each substrate and were unique to the inoculum source. Our data suggest that the activity of kefir bacterial populations differs and that kefir consumption changes the abundance and activity of the fecal microbiota of dogs, justifying in vivo investigation.

High-Resolution Melting Analysis Potential for Saccharomyces cerevisiae var. boulardii Authentication in Probiotic-Enriched Food Matrices

To date, the only probiotic yeast with evidence of health-promoting effects is Saccharomyces cerevisiae var. boulardii. The expanded market including dietary supplements and functional foods supplemented with Saccharomyces cerevisiae var. boulardii creates an environment conductive to food adulterations, necessitating rapid testing to verify product probiotic status. Herein, qPCR-HRM analysis was tested for probiotic yeast identification. The effectiveness of the primer pairs' set was examined, designed to amplify heterogeneous regions in (a) rDNA sequences previously designed to identify food-derived yeast and (b) genes associated with physiological and genotypic divergence of Saccharomyces cerevisiae var. boulardii. Preliminary tests of amplicons' differentiation power enabled the selection of interspecies sequences for 18SrRNA and ITS and genus-specific sequences HO, RPB2, HXT9 and MAL11. The multi-fragment qPCR-HRM analysis was sufficient for culture-dependent Saccharomyces cerevisiae var. boulardii identification and proved effective in the authentication of dietary supplements' probiotic composition. The identification of S. cerevisiae var. boulardii in complex microbial mixtures of kefir succeeded with more specific intragenus sequences HO and RPB2. The predominance of S. cerevisiae var. boulardii in the tested matrices, quantitatively corresponded to the probiotic-enriched food, was crucial for identification with qPCR-HRM analysis. Considering the reported assumptions, qPCR-HRM analysis is an appropriate tool for verifying probiotic-enriched food.

Unveiling the overlooked fungi: the vital of gut fungi in inflammatory bowel disease and colorectal cancer

The fungi of the human microbiota play important roles in the nutritional metabolism and immunological balance of the host. Recently, research has increasingly emphasised the role of fungi in modulating inflammation in intestinal diseases and maintaining health in this environment. It is therefore necessary to understand more clearly the interactions and mechanisms of the microbiota/pathogen/host relationship and the resulting inflammatory processes, as well as to offer new insights into the prevention, diagnosis and treatment of inflammatory bowel disease (IBD), colorectal cancer (CRC) and other intestinal pathologies. In this review, we comprehensively elucidate the fungal-associated pathogenic mechanisms of intestinal inflammation in IBD and related CRC, with an emphasis on three main aspects: the direct effects of fungi and their metabolites on the host, the indirect effects mediated by interactions with other intestinal microorganisms and the immune regulation of the host. Understanding these mechanisms will enable the development of innovative approaches based on the use of fungi from the resident human microbiota such as dietary interventions, fungal probiotics and faecal microbiota transplantation in the prevention, diagnosis and treatment of intestinal diseases.

Probiotic and Functional Attributes of Yeasts Isolated from Different Traditional Fermented Foods and Products

Though numerous bacteria have been used as probiotics by industries, at present, Saccharomyces boulardii and Saccharomyces cerevesiae are the only yeast probiotics which are industrially exploited. In view of this, yeast probiotics were isolated from traditional fermented foods and products collected from different parts of Karnataka, India. In this work, we have studied the probiotic attributes of ten yeast isolates isolated from different traditionally fermented foods and products. About 73 yeast isolates were initially isolated by serially diluting the samples and plating on the Potato Dextrose Agar (PDA) plates. The spot assay was performed to screen the yeast isolates against test pathogens. Ten isolates were selected based on their significant antimicrobial activity. These isolates were subjected to biochemical characterization and then assessed for probiotic properties. The ability of probiotics to endure at pH 2.0 and tolerate bile conditions (0.3%) are crucial attributes for the survival in the gastrointestinal tract (GIT). The yeast isolates were also assessed for cell surface hydrophobicity and autoaggregation capabilities. All the ten isolates showed endurance in GIT tract and > 40% of adhesion. The study further examined cholesterol assimilation, antioxidant and antagonistic properties of the yeasts. Subsequently, the molecular characterization was performed by isolating the DNA of yeast isolates by phenol-chloroform method and identified molecularly through sequencing of D1/D2 regions. The isolates tested negative for gelatinase and DNase and were non-haemolytic indicating they are safe for consumption. Among ten isolates, Meyerozyma guillermondii (MYSY23), Meyerozyma caribbica (MYSY22) and Meyerozyma guillermondii (MYSY19) showed significant results for all probiotic and functional characteristics with greater than 65% survivability in GIT tract and > 50% of antagonistic activity against test pathogens and also proved non-cytotoxic and safe. These findings suggest that yeasts with significant probiotic attributes could be recommended for various probiotic application.

In Vitro Characterization and Identification of Potential Probiotic Yeasts Isolated from Zaopocu, a Traditional Fermented Dregs Vinegar from Hainan Island

Recently, there has been an increasing interest in researching fermented food-derived yeasts as probiotics because they offer a natural and diverse source of potential strains with unique functional properties and health benefits. In this study, 13 yeast strains isolated from Zaopocu (ZPC), a traditional fermented dregs vinegar on Hainan Island, China, were evaluated for their probiotic characteristics in vitro. Yeast identification was conducted through 5.8S-ITS region sequencing, revealing Kodamaea ohmeri as the predominantly isolated species (ZPC_Y3, Y5, Y6, Y11), followed by Pichia kudriavzevii (ZPC_Y2, Y13, Y14), Rhodotorula mucilaginosa (ZPC_Y9, Y10), Pichia fermentans (ZPC_Y8, Y12), Pichia kluyveri (ZPC_Y4), and Pichia occidentalis (ZPC_Y1). Except for ZPC_Y4, ZPC_Y8, and ZPC_Y12, all isolated yeasts exhibited stable growth at 37 °C. The survival rates of all test strains exceeded 60% under challenging conditions at pH = 2 and 0.3% bile salt, along with strong antioxidant activity (> 5 6%), notable autoaggregation (> 70%), and varying levels of cell hydrophobicity with xylene (ranging from 35.32 ± 8.57% to 89.73 ± 4.84%). In addition, all isolates showed resistance to multiple antibiotics, along with antagonistic activity, and were deemed safe as none exhibited hemolytic, gelatinase, or DNase activities. Significantly, two P. kudriavzevii strains (ZPC_Y2, Y14) exhibited the production of catalase, lipase, and β-galactosidase, along with the capacity to synthesize gamma-aminobutyric acid (GABA). In summary, this preliminary study represents the first attempt to identify and characterize potential probiotic yeast strains isolated from Zaopocu, providing a theoretical basis for exploring their application in developing novel therapeutic probiotics.

Biodiversity and probiotic potential of yeasts isolated from sumbawa horse milk

BACKGROUND

The microbial composition of Sumbawa Horse Milk is influenced by various factors, including environmental elements that encompass geographical location, climate, and conditions specific to Sumbawa. This study aimed to determine the biodiversity and genetic diversity of the microbiome of Sumbawa Horse Milk, with an emphasis on yeast.

METHODS

The diversity and group of yeast isolates were evaluated by the sequence-related amplified polymorphism (SRAP) method using ME2F-EM15R (1) and ME2F-EM12R (2) primers. Molecular identification using 18 S rRNA primers was then carried out on nine selected isolates (K_21, K_31, K_42, K_45, K_1, K_6, K_8, K_17, and K_19) to determine the type of yeast. Probiotic candidate tests were carried out on three isolates, namely K_1, K_6 and K_8.

RESULTS

Analysis with NTSYS software on the SRAP results using Primer 1 revealed the presence of two major groups, where Group I was exclusively comprised of K_45 isolate, whereas the other isolates belonged to Group II. On the other hand, analysis with NTSYS software on the SRAP analysis with Primer 2 also showed two major groups with different compositions. Group I consisted of isolates K_39, 38, 37, 36, 35, 34, 33, 31, 29, 28, 27, 26, 25, 24, 23, 22, and 21, while the remaining isolates belonged to Group II. Results of 18 S rRNA analysis demonstrated that K_17 and K_19 had 99.8 and 100% similarity, respectively, and identified as Candida humilis. K_21, K_31, and K_45 were identified as having a 100% similarity to Clavispora lusitaniae, while K_42 had a 99.8% similarity to Candida parapsilosis. Three isolates were identified as belonging to the genus Ogataea, namely Ogataea polymorpha (K_6 and K_8) and Ogataea siamensis (K_1) with similarity of 100% and 99.8%, respectively.

CONCLUSIONS

These findings suggest that the three yeast have potential as probiotics.

Isolation, identification, and in vitro probiotic characterization of forty novel Bifidobacterium strains from neonatal feces in Erzurum province, Türkiye

BACKGROUND

Neonatal feces are one of the most important sources for probiotic isolation. The purpose of this study was the isolation and identification of Bifidobacterium spp. from neonatal feces and the evaluation of in vitro probiotic properties of strains including safety tests.

RESULTS

A total of 40 isolates were obtained from 14 healthy newborns' feces in Erzurum province, Türkiye. By their rep-PCR patterns and 16S rRNA gene sequences, isolates were identified as 26 Bifidobacterium breve and 14 Bifidobacterium longum. Fifteen of the isolates tolerated bile salts and showed high resistance to simulated gastric juice. Isolates exhibited varying rates of auto-aggregation and hydrophobicity. In addition, most of the isolates displayed antibacterial activity against Escherichia coli O157:H7, Staphylococcus aureus ATCC 29213, Salmonella Typhimurium RSHMB 95091, and Pseudomonas aeruginosa ATCC 9027. However, only one strain showed bile salt hydrolase activity and two strains showed the ability to produce H2O2. Bifidobacterium strains were generally sensitive to the tested antibiotics and lacked kanamycin, gentamicin, and streptomycin resistance genes, and hemolytic and DNAse activities. On the other hand, it was determined that five strains had various virulence genes including gelE, esp, efaAfs, hyl, and ace.

CONCLUSION

Results of the present study suggested that B. longum BH28, B. breve BH4 and B. breve BH5 strains have the potential as probiotic candidates for further studies. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Evaluation of the probiotic potential of yeast isolated from kombucha in New Zealand

The current study investigated the in vitro probiotic potential of yeast isolated from kombucha, a tea beverage fermented with a symbiotic culture of acetic acid bacteria and yeast. A total of 62 yeast strains were previously isolated from four different commercial kombucha samples sold in New Zealand. Fifteen representative isolates belonging to eight different species were evaluated for their growth under different conditions (temperature, low pH, concentrations of bile salts, and NaCl). Cell surface characteristics, functional and enzymatic activities of the selected strains were also studied in triplicate experiments. Results showed that six strains (Dekkera bruxellensis LBY1, Sachizosaccharomyces pombe LBY5, Hanseniaspora valbyensis DOY1, Brettanomyces anomalus DOY8, Pichia kudraivzevii GBY1, and Saccharomyces cerevisiae GBY2) were able to grow under low-acid conditions (at pH 2 and pH 3) and in the presence of bile salts. This suggests their potential to survive passage through the human gut. All 15 strains exhibited negative enzymatic activity reactions (haemolytic, gelatinase, phospholipase, and protease activities), and thus, they can be considered safe to consume. Notably, two of the fifteen strains (Pichia kudraivzevii GBY1 and Saccharomyces cerevisiae GBY2) exhibited desirable cell surface hydrophobicity (64.60-83.87%), auto-aggregation (>98%), co-aggregation, resistance to eight tested antibiotics (ampicillin, chloramphenicol, colistin sulphate, kanamycin, nalidixic acid, nitrofurantoin, streptomycin, and tetracycline), and high levels of antioxidant activities (>90%). Together, our data reveal the probiotic activities of two yeast strains GBY1 and GBY2 and their potential application in functional food production.

Multilocus sequence typing of L. bulgaricus and S. thermophilus strains from Turkish traditional yoghurts and characterisation of their techno-functional roles

In this study, Streptococcus thermophilus and Lactobacillus bulgaricus strains from traditional Turkish yoghurts were isolated, identified by 16S rRNA sequencing and genotypically 14 S. thermophilus and 6 L. bulgaricus strains were obtained as distinct strains by MLST analysis. Lactic acid production levels of the L. bulgaricus strains were higher than S. thermophilus strains. HPLC analysis showed that EPS monosaccharide composition of the strains mainly consisted of glucose and galactose. In general, all strains were found to be susceptible for antibiotics, except some strains were resistance to gentamicin and kanamycin. Apart from two strains of S. thermophilus, all strains displayed strong auto-aggregation level greater than 95% at 24 h incubation. S. thermophilus strains showed higher cell surface hydrophobicity than L. bulgaricus strains. This study demonstrated the isolation, identification, genotypic discrimination and techno-functional features of wild type yoghurt starter cultures which can potentially find place in industrial applications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01366-2.

Drying of probiotics to enhance the viability during preparation, storage, food application, and digestion: A review

Functional food products containing viable probiotics have become increasingly popular and demand for probiotic ingredients that maintain viability and stability during processing, storage, and gastrointestinal digestions. This has resulted in heightened research and development of powdered probiotic ingredients. The aim of this review is to overview the development of dried probiotics from upstream identification to downstream applications in food. Free probiotic bacteria are susceptible to various environmental stresses during food processing, storage, and after ingestion, necessitating additional materials and processes to preserve their activity for delivery to the colon. Various classic and emerging thermal and nonthermal drying technologies are discussed for their efficiency in preparing dehydrated probiotics, and strategies for enhancing probiotic survival after dehydration are highlighted. Both the formulation and drying technology can influence the microbiological and physical properties of powdered probiotics that are to be characterized comprehensively with various techniques. Furthermore, quality control during probiotic manufacturing and strategies of incorporating powdered probiotics into liquid and solid food products are discussed. As emerging technologies, structure-design principles to encapsulate probiotics in engineered structures and protective materials with improved survivability are highlighted. Overall, this review provides insights into formulations and drying technologies required to supplement viable and stable probiotics into functional foods, ensuring the retention of their health benefits upon consumption.

Identification of four autochthonous yeasts from the intestines of goldfish, Carassius auratus with potential probiotic properties and their effects on the most common fish bacterial pathogens

In aquaculture, probiotic yeasts have gained particular interest because of their numerous health benefits for farmed fish. Many autochthonous yeasts have been isolated and identified from fish species with potential probiotic characteristics. In the present study, four autochthonous yeast strains were identified and characterized from the intestinal tracts of 16 healthy goldfish, Carassius auratus. Their in vitro probiotic properties were examined in terms of cell surface hydrophobicity, co-aggregation, and tolerability to different pH values and bile salt concentrations. These strains were identified by culture characters and sequence analysis of ITS (Internal Transcribed Spacer) gene regions. Four strains, namely Cutaneotrichosporon jirovecii isolate jpn01, Debaryomyces nepalensis isolate jpn02, Blastobotrys proliferans isolate jpn05, and Diutina catenulata isolate jpn06, were identified and added to the NCBI GenBank with accession numbers defined as MT584874.1, MT584873.1, MT649918.1, and MT501155.1, respectively. Results demonstrated the capability of these strains to co-aggregate with several fish-associated bacterial pathogens such as Lactococcus garvieae, Vagococcus salmoninarum, Vibrio anguillarum, Yersinia ruckeri, and Aeromonas hydrophila. Only the jpn05 strain did not co-aggregate with A. hydrophila. All identified yeast isolates could grow and tolerate low pH conditions (pH 2.0) and bile salt concentrations (up to 1.5%). Of interest, the hydrophobicity (%) of the yeast isolates was 80%, 94.0%, 80.6%, and 66.4% for jpn01, jpn02, jpn05, and jpn06 isolates, respectively. In this context, our data provide important in vitro evidence for the potential probiotic features of the yeast isolates. These strains could be considered candidate probiotic yeasts; however, their application in aquaculture nutrition necessitates further in vivo assays.

The synergistic effect of titanium dioxide nanoparticles and yeast isolated from fermented foods in reduction of aflatoxin B1

The presence of aflatoxins in food products can lead to health risks in human societies. Therefore, in the present study, the effect of yeast strains isolated from fermented products and titanium dioxide nanoparticles (TiO2-NPs) was studied on aflatoxin reduction. Yeast strains were isolated from fermented products such as sweet fruits and dairy products and identified using biochemical, ascospore (testing by culture medium optimization V8 which is called V8NLF), and molecular methods. The probiotic activity of four selected yeasts was evaluated. Then, the effect of selected yeast isolates and TiO2-NPs on reducing aflatoxin B1 (AFB1) in the medium was studied by measuring AFB1 using ELISA and HPLC. The results of biochemical and molecular identification experiments indicate that the selected strain (Y1) is Saccharomyces cerevisiae. The selected strains showed good tolerance to different concentrations of bile salt, pH, and NaCl, indicating appropriate probiotic activity. It also showed antimicrobial activity against Escherichia coli, Shigella dysenteriae, and Salmonella typhimurium. Selected strain and TiO2-NPs showed AFB1 reducing activity in the medium and when combined, showed synergistic effects in reducing AFB1. TiO2-NPs in combination with selected yeast strains have a high ability to remove AFB1 from the medium and, therefore, can be used for future studies.

In Vitro Evaluation of the Technological and Probiotic Potential of Pichia kudriavzevii Strains Isolated from Traditional Fermented Foods

The isolation of endogenous yeast strains from traditionally fermented food products to use as functional starter cultures has become more popular for improved food safety, quality, and beneficial health effects. In this study, 107 Pichia kudriavzevii strains were isolated from sourdough, shalgam, tarhana, artisanal Tulum cheese, and yogurt. The strains were identified by DNA fingerprinting using iPBS-PCR method before technological and probiotic characterization. The multivariate statistical approach revealed that five strains were most promising in terms of technological characterization, including different harsh growth conditions. These strains were also examined in terms of probiotic properties with a commercial S. cerevisiae var boulardii MYA-796 strain. The multivariate statistical analyses indicated that P. kudriavzevii 5S5 were most promising in in vitro probiotic properties such as surviving in human GI conditions, adhering to intestinal cell lines, and exhibiting high hydrophobicity. Therefore, it seems to be a great starter candidate for the production of functional fermented food products.

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.

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.

Isolation of Yeasts from Some Homemade Fermented Cow-Milk Products of Sikkim and Their Probiotic Characteristics

Dahi and chhurpi are the homemade, mildly acidic and mouthfeel fermented dairy products of Sikkim in India. Since yeasts co-exist among traditional fermented dairy foods, we believe that some species of yeasts may have some probiotic properties. Hence, the present study is aimed at screening some probiotic yeasts from dahi and chhurpi. A total of 3438 yeasts were isolated from 40 samples of dahi (1779 isolates) and 40 chhurpi (1659 isolates) and were preliminarily screened for probiotic properties on the basis of survival in low pH, resistance to bile salts and the percentage of hydrophobicity, out of which only 20 yeasts were selected for in vitro and genetic screening of probiotic properties. Saccharomyces cerevisiae DJT-2 and Debaryomyces prosopidis CPA-55 showed the highest hydrophobicity of 97.54% and 98.33%, respectively. S. cerevisiae DRC-42 and S. cerevisiae CGI-29 showed 93.88% and 91.69% auto-aggregation, respectively. All yeasts showed co-aggregation properties against pathogenic bacteria. Kluyveromyces marxianus DPA-41 and Pichia kudriavzevii CNT-3 showed excellent deconjugation activities. Probiotic genes for acid tolerance, bile tolerance, adhesion and antimicrobial activity were detected in S. cerevisiae DAO-17, K. marxianus DPA-41, S. cerevisiae CKL-10 and P. kudriavzevii CNT-3. Based on the results of in vitro and genetic screening of probiotic yeasts strains, S. cerevisiae DAO-17 (dahi), S. cerevisiae CKL-10 (chhurpi), P. kudriavzevii CNT-3 (chhurpi) and K. marxianus DPA-41(dahi) were selected as the potential probiotic yeasts.

Characterization of potential probiotic bacteria Enterococcus faecium MC-5 isolated from the gut content of Cyprinus carpio specularis

The goal of this study was to determine the unique characteristics of Enterococcus faecium MC-5, a probiotic bacteria isolated from the intestine of a fish, Cyprinus carpio specularis, collected from Dal Lake in Srinagar, Kashmir, India. For this, the important valuable probiotic attributes, some functional properties, and safety assessments were analyzed in-vitro for the strain MC-5. The strain E. faecium MC-5 exhibited high resistance to low pH, high bile salt, lysozyme, and phenol. The strain MC-5 showed excellent auto- and co-aggregation properties and displayed remarkable hydrophobicity towards various tested hydrocarbons which suggested that the strain possesses venerable adhesion properties. Apart from these, the cell-free supernatant (CFS) of strain MC-5 exhibited phenomenal antimicrobial activity against the tested pathogens. A scanning electron microscope (SEM) image revealed strain MC-5 finely adhered to human colon adenocarcinoma cells (HCT-15 cells). The strain MC-5 showed high bile salt hydrolase activity and excellent cholesterol removal ability of 70.27%. The intact cells of strain MC-5 also showed strong DPPH scavenging activity. The EPS produced by E. faecium MC-5 inhibited the adhesion of Listeria monocytogenes, Staphylococcus aureus, and Salmonella enterica on HCT-15 cells with maximum inhibition rates of 41.82, 40.34, and 55.51%, respectively for displacement assay, which was higher as compared to exclusion (26.06, 26.11, and 39.23%) and competition assays (30.06, 26.7, and 41.20%). Strain MC-5 did not exhibit hemolysis and was also found susceptible to vancomycin and other clinically important antibiotics. When evaluating all the results from the present study, it is propounded that strain MC-5 has enviable probiotic characteristics and thus can be used as bio-protective cultures and/or bio-shield in food and pharmaceutical industries.

Yeasts from Iranian traditional milk kefir samples: isolation, molecular identification and their potential probiotic properties

Milk kefir is a fermented dairy product with numerous attributed health benefits due to the presence of a complex eukaryotic and prokaryotic microbiota. In this study, a total number of 26 yeast isolates were obtained from eight kefir samples from three different cities of Iran. The isolates belonged to Kluyveromyces marxianus, Saccharomyces cerevisiae, Pichia fermentans and P. kudriavzevii. The potential probiotic characteristics of the isolates were evaluated based on their ability to tolerate the stimulated condition of the gastrointestinal tract. In addition, hemolytic activity, adherence to different solvents, auto-aggregation, adhesion to the epithelial intestine-derived cells and antimicrobial activity of the selected isolates were evaluated. Overall, four yeast strains (three strains of S. cerevisiae and one strain of P. fermentans) showed resistance and survival ability against the gastrointestinal physiological conditions including acidic pH, presence of bile salt and digestive enzymes. They were able to grow at 37 °C and had the capacity to adhere to epithelial intestine-derived cells. These results suggest that the selected strains can be proper candidates as probiotic yeast strains for the development of novel functional foods.

Exploring biotechnological and functional characteristics of probiotic yeasts: A review

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In this review, the probiotic attributes of yeasts other than Saccharomyces boulardii and the various applications of probiotic yeast in biotechnology have been explored.

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This review comprises of the probiotic attributes, antagonistic activity against pathogens, plant growth promoting attributes, industrial application and their biotherapeutic potentials.

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Advanced and additional studies on non-Saccharomyces yeasts are necessary prior to administer these yeasts as potential probiotics for health and wellbeing.

Probiotics are vital and beneficial organisms which offers the health benefits to the host organisms. The fungal probiotic field is one of the developing fields nowadays. Yeast has an enormous and diverse group of microorganisms that is attracting and expanding the attention from researchers and industries. Saccharomyces boulardii, the only patented strain belonging to yeast genera for the human use, has been broadly evaluated for its probiotic effect. Yeasts belonging to the genera Debaryomyces, Pichia, Yarrowia, Meyerozyma, Kluyveromyces etc.., have attained more interest because of their beneficial and probable probiotic features. These yeast probiotics produce VOCs (Volatile organic compounds), mycocins and antimicrobials which shows the antagonistic effect against pathogenic fungi and bacteria. Additionally, those yeasts have been recorded as good plant growth promoting microorganisms. Yeast has an important role in environmental applications such as bioremediation and removal of metals like chromium, mercury, lead etc., from waste water. Probiotic yeasts with their promising antimicrobial, antioxidant, anticancer properties, cholesterol assimilation and immunomodulatory effects can also be utilized as biotherapeutics. In this review article we have made an attempt to address important yeast probiotic attributes.

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.

In Vitro Study of Probiotic, Antioxidant and Anti-Inflammatory Activities among Indigenous Saccharomyces cerevisiae Strains

Nowadays, the interest toward products containing probiotics is growing due to their potential health benefits to the host and the research is focusing on search of new probiotic microorganisms. The present work was focused on the characterization of indigenous Saccharomyces cerevisiae strains, isolated from different food matrixes, with the goal to select strains with probiotic or health-beneficial potential. A preliminary screening performed on fifty S. cerevisiae indigenous strains, in comparison to a commercial probiotic strain, allowed to individuate the most suitable ones for potential probiotic aptitude. Fourteen selected strains were tested for survival ability in the gastrointestinal tract and finally, the strains characterized for the most important probiotic features were analyzed for health-beneficial traits, such as the content of glucan, antioxidant and potential anti-inflammatory activities. Three strains, 4LBI-3, LL-1, TA4-10, showing better attributes compared to the commercial probiotic S.cerevisiae var. boulardii strain, were characterized by interesting health-beneficial traits, such as high content of glucan, high antioxidant and potential anti-inflammatory activities. Our results suggest that some of the tested S. cerevisiae strains have potential as probiotics and candidate for different applications, such as dietary supplements, and starter for the production of functional foods or as probiotic to be used therapeutically.

Evaluation of the Potential Probiotic Yeast Characteristics with Anti-MRSA Abilities

Methicillin-resistant Staphylococcus aureus (MRSA) is a disreputable pathogenic bacterium that has been proven to colonize the intestinal tract. The goal of this study is to find anti-MRSA probiotic yeast from food and evaluate its probiotic characteristics and safety. Finally, 15 strains were isolated from fruit peel with anti-MRSA ability. Using DNA sequence analysis, they were identified as the genus Hanseniaspora (7 strains) and Starmerella (8 strains). Starmerella bacillaris CC-PT4 (CGMCC No. 23573) that was isolated from the grape peel has good auto-aggregation ability and hydrophobicity, and can tolerate 0.3% bile, pH 2, simulated gastric fluid (SGF), and simulated intestinal fluid (SIF). Strikingly, Starmerella bacillaris CC-PT4, like commercial probiotic Saccharomyces boulardii CNCM I-745 (Florastor ^®), can adapt to the temperature of the human body (37 ℃). After safety assessment, this strain is sensitive to amphotericin B and cannot produced β-hemolytic activities. Overall, this study provides a new candidate for probiotic yeast with anti-MRSA ability.

Probiotic Yeast Saccharomyces: Back to Nature to Improve Human Health

Saccharomyces cerevisiae var. boulardii is best known for its treatment efficacy against different gastrointestinal diseases. This probiotic yeast can significantly protect the normal microbiota of the human gut and inhibit the pathogenicity of different diarrheal infections. Several clinical investigations have declared S. cerevisiae var. boulardii a biotherapeutic agent due to its antibacterial, antiviral, anti-carcinogenic, antioxidant, anti-inflammatory and immune-modulatory properties. Oral or intramuscular administration of S. cerevisiae var. boulardii can remarkably induce health-promoting effects in the host body. Different intrinsic and extrinsic factors are responsible for its efficacy against acute and chronic gut-associated diseases. This review will discuss the clinical and beneficial effects of S. cerevisiae var. boulardii in the treatment and prevention of different metabolic diseases and highlight some of its health-promising properties. This review article will provide fundamental insights for new avenues in the fields of biotherapeutics, antimicrobial resistance and one health.

Isolation of Efficient Xylooligosaccharides-Fermenting Probiotic Lactic Acid Bacteria from Ethnic Pickled Bamboo Shoot Products

Xylooligosaccharides (XOSs) are produced from xylan, which is a component of the hemicellulose that can be found in bamboo shoots. Naw Mai Dong, an ethnic pickled bamboo shoot product of northern Thailand, is generally characterized as acidic and has a sour taste. It can be considered a potential source of probiotic lactic acid bacteria (LAB). This study aimed to isolate efficient XOSs-fermenting probiotic LAB from ethnic pickled bamboo shoot products. A total of 51 XOSs-fermenting LAB were recovered from 24 samples of Naw Mai Dong, while 17 strains exhibited luxuriant growth in xylose and XOSs. Among these, seven strains belonging to Levicaseibacillus brevis and Pediococcus acidilactici exhibited similar growth in glucose, xylose, and XOSs, while the rest showed a weaker degree of growth in xylose and XOSs than glucose. Sixteen strains exhibited resistance under gastrointestinal tract conditions and displayed antimicrobial activity against foodborne pathogens. Notably, Lv. brevis FS2.1 possessed the greatest probiotic properties, with the highest %hydrophobicity index and %auto-aggregation. Effective degradation and utilization of XOSs by probiotic strains are dependent upon xylanase and β-xylosidase production, as well as xylose metabolism. It can be concluded that pickled bamboo shoot products can be a beneficial source of XOSs-fermenting probiotic LAB.

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.

Metagenomic and Functional Characterization of Two Chilean Kefir Beverages Reveals a Dairy Beverage Containing Active Enzymes, Short-Chain Fatty Acids, Microbial β-Amyloids, and Bio-Film Inhibitors

Kefir beverage is a probiotic food associated with health benefits, containing probiotic microorganisms and biomolecules produced during fermentation. The microbial composition of these beverages varies among countries, geographical regions, and the substrates, therefore, the characterization of kefir beverages is of great relevance in understanding their potential health-promoting and biotechnological applications. Therefore, this study presents the metagenomic and functional characterization of two Chilean kefir beverages, K02 and K03, through shotgun and amplicon-based metagenomic, microbiological, chemical, and biochemical studies. Results show that both beverages’ microbiota were mainly formed by Bacteria (>98%), while Eukarya represented less than 2%. Regarding Bacteria, the most abundant genera were Acetobacter (93.43% in K02 and 80.99% in K03) and Lactobacillus (5.72% in K02 and 16.75% in K03), while Kazachstania was the most abundant genus from Eukarya (42.55% and 36.08% in K02 and K03). Metagenomic analyses revealed metabolic pathways for lactose and casein assimilation, biosynthesis of health-promoting biomolecules, and clusters for antibiotic resistance, quorum sensing communication, and biofilm formation. Enzymatic activities, microbial β-amyloids, and short-chain fatty acids (acetic acid and propionic acid) were also detected in these beverages. Likewise, both kefir beverages inhibited biofilm formation of the opportunistic pathogen Pseudomonas aeruginosa.

Lacticaseibacillus rhamnosus GG Survival and Quality Parameters in Kefir Produced from Kefir Grains and Natural Kefir Starter Culture

The study aimed to determine the effect of starter cultures (kefir grains and natural kefir starter culture without grains) on Lacticaseibacillus rhamnosus GG (LGG) survival and on the quality characteristics of kefir. To this end, the viability of probiotic L. rhamnosus GG strain and the rheological properties and quality parameters of kefir beverages were tested during storage over 21 days at 4 °C. The final LGG counts were 7.71 and 7.55 log cfu/mL in natural kefir starter culture and kefir grain, respectively. When prepared with probiotic bacteria, the syneresis values of kefir prepared using natural kefir starter culture was significantly lower (p < 0.05) than that of kefir made using grains. However, the viscosity indices, hysteresis loop, and dynamic moduli were similar between kefir made with natural kefir starter culture and other kefir formulations (p > 0.05). Moreover, all samples showed shear-thinning behavior. The flavor scores for kefir prepared using natural kefir starter culture were significantly higher than for the other samples (p < 0.05), but overall acceptability was similar at the 10-day assessment across both starters (with and without grain) after the addition of probiotic bacteria (p > 0.05). Overall, the results indicate that natural kefir starter culture could be a potential probiotic carrier.

Anti-salmonella properties of kefir yeast isolates: An in vitro screening for potential infection control

The rise of antibiotic resistance has increased the need for alternative ways of preventing and treating enteropathogenic bacterial infection. Various probiotic bacteria have been used in animal and human. However, Saccharomyces boulardii is the only yeast currently used in humans as probiotic. There is scarce research conducted on yeast species commonly found in kefir despite its claimed potential preventative and curative effects. This work focused on adhesion properties, and antibacterial metabolites produced by Kluyveromyces lactis and Saccharomyces unisporus isolated from traditional kefir grains compared to Saccharomyces boulardii strains. Adhesion and sedimentation assay, slide agglutination, microscopy and turbidimetry assay were used to analyze adhesion of Salmonella Arizonae and Salmonella Typhimurium onto yeast cells. Salmonella growth inhibition due to the antimicrobial metabolites produced by yeasts in killer toxin medium was analyzed by slab on the lawn, turbidimetry, tube dilution and solid agar plating assays. Alcohol and antimicrobial proteins production by yeasts in killer toxin medium were analyzed using gas chromatography and shotgun proteomics, respectively. Salmonella adhered onto viable and non-viable yeast isolates cell wall. Adhesion was visualized using scanning electron microscope. Yeasts-fermented killer toxin medium showed Salmonella growth inhibition. The highest alcohol concentration detected was 1.55%, and proteins with known antimicrobial properties including cathelicidin, xanthine dehydrogenase, mucin-1, lactadherin, lactoperoxidase, serum amyloid A protein and lactotransferrin were detected in yeasts fermented killer medium. These proteins are suggested to be responsible for the observed growth inhibition effect of yeasts-fermented killer toxin medium. Kluyveromyces lactis and Saccharomyces unisporus have anti-salmonella effect comparable to Saccharomyces boulardii strains, and therefore have potential to control Salmonella infection.

Exploitation of Yeasts with Probiotic Traits for Kefir Production: Effectiveness of the Microbial Consortium

Kefir is a fermented milk made by beneficial lactic acid bacteria and yeasts inoculated as grains or free cultures. In this work, five yeast strains with probiotic aptitudes belonging to Candida zeylanoides, Yarrowia lipolytica, Kluyveromyces lactis, and Debaryomyces hansenii species were assessed in a defined consortium, in co-culture with a commercial strain of Lactobacillus casei, in order to evaluate the yeasts’ fermentation performance during kefir production, using different milks. The concentration of each yeast was modulated to obtain a stable consortium that was not negatively affected by the bacteria. Furthermore, all yeasts remained viable for five weeks at 4 °C, reaching about 8.00 Log CFU in 150 mL of kefir, a volume corresponding to a pot of a commercial product. The yeasts consortium showed a suitable fermentation performance in all milks, conferring peculiar and distinctive analytical and aromatic properties to the kefirs, confirmed by a pleasant taste. Overall, the panel test revealed that the cow’s and sheep’s kefir were more appreciated than the others; this evaluation was supported by a distinctive fermentation by-products’ content that positively influences the final aroma, conferring to the kefir exalted taste and complexity. These results allow us to propose the yeasts consortium as a versatile and promising multistarter candidate able to affect industrial kefir with both recognizable organoleptic properties and probiotic aptitudes.

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.

Determination of selenite and selenomethionine in kefir grains by reversed-phase high-performance liquid chromatography-inductively coupled plasma-optical emission spectrometry

A new and efficient reversed-phase high-performance liquid chromatography-inductively coupled plasma-optical emission spectrometry method was developed for the simultaneous separation and determination of SeO₃ ^2- and seleno-dl-methionine in kefir grains. For the system, limits of detection and quantitation values for SeO₃ ^2- and seleno-dl-methionine were calculated as 0.52/1.73 mg/kg (as Se) and 0.26/0.87 mg/kg (as Se), respectively. After performing the system analytical performance, recovery experiment was done for kefir grains and percent recovery results for SeO₃ ^2- and seleno-dl-methionine were calculated as 98.4 ± 0.8% and 93.6 ± 1.0%, respectively. It followed by the feeding studies that the kefir grains were exposed to three different concentrations of SeO₃ ^2- (20, 30, and 50 mg/kg) for approximately 4 days at room temperature to investigate the conversion/non-conversion of SeO₃ ^2- to seleno-dl-methionine. Next, the fed grains were extracted with tetramethylammonium hydroxide pentahydrate solution (20%, w/w) and then sent to the developed system. There was no detectable seleno-dl-methionine found in fed kefir grains at different concentrations of SeO₃ ^2- while inorganic or elemental selenium in the fed kefir grains was determined between 1579.5 - 3116.0 mg/kg (as Se). Selenium species in the kefir grains samples was found in the form of SeO₃ ^2- proved by using an anion exchange column.

A Comprehensive Assessment of the Safety of Blautia producta DSM 2950

In recent years, Blautia has attracted attention for its role in ameliorating host diseases. In particular, Blautia producta DSM 2950 has been considered a potential probiotic due to its ability to mitigate inflammation in poly(I:C) induced HT-29 cells. Thus, to promote the development of indigenous intestinal microorganisms with potential probiotic function, we conducted a comprehensive experimental analysis of DSM 2950 to determine its safety. This comprised a study of its potential virulence genes, antibiotic resistance genes, genomic islands, antibiotic resistance, and hemolytic activity and a 14-day test of its acute oral toxicity in mice. The results indicated no toxin-related virulence genes in the DSM 2950 genome. Most of the genomic islands in DSM 2950 were related to metabolism, rather than virulence expression. DSM 2950 was sensitive to most of the tested antibiotics but was tolerant of treatment with kanamycin, neomycin, clindamycin, or ciprofloxacin, probably because it possessed the corresponding antibiotic resistance genes. Oral acute toxicity tests indicated that the consumption of DSM 2950 does not cause toxic side effects in mice. Overall, the safety profile of DSM 2950 confirmed that it could be a candidate probiotic for use in food and pharmaceutical preparations.

Probiotic potential of γ-aminobutyric acid (GABA)-producing yeast and its influence on the quality of cheese

Kazakh cheese is a traditional dairy product in Xinjiang, China. To study the function and potential probiotic characteristics of yeast in Kazakh cheese and its contribution to cheese fermentation, we screened the γ-aminobutyric acid (GABA)-producing yeasts Pichia kudriavzevii 1-21, Kluyveromyces marxianus B13-5, Saccharomyces cerevisiae DL6-20, and Kluyveromyces lactis DY1-10. We investigated the potential probiotic properties of these strains and their use in cheese fermentation (cheeses designated CSP, CSM, CSS, and CSI, respectively); a control with no added yeast was designated CS. The results showed that the 4 yeast strains all showed high self-polymerization (2- and 24-h autoaggregation capacity of >80 and 90%, respectively), hydrophobicity (40-92% variation, low hydrophobicity in xylene, but within the range of probiotics), and the ability to survive the gastrointestinal tract (survival rate >75% after simulation), indicating the probiotic ability of the strains in vitro. The GABA production capacity of the CSM cheese increased (to 95.6 mg/100 g), but its protein content did not change significantly, and amino acid degradation was obvious. The GABA production capacity of the CSS cheese decreased (to 450 mg/kg); its protein content declined, and its amino acid content increased. Except for water and protein, we found no obvious differences in most physical and chemical indicators. Kluyveromyces marxianus B13-5 helped to form the desired texture. Multivariate statistical analysis showed that fermentation of the cheese with the 4 yeasts improved the production of esters and alcohols. The CSS cheese had good aroma production performance, because S. cerevisiae DL6-20 produced high concentrations of isoamyl alcohol, hexanoic acid ethyl ester, benzyl alcohol, octanoic acid ethyl ester, 3-hydroxy-2-butanone, and hexanoic acid; the content of 2-methyl-propanoic acid was low. Compared with the CSP cheese, the CSI and CSM cheeses had a fruitier aroma and a milder odor, but the CSI and CSM cheeses had high concentrations of ethyl acetate, butanoic acid, ethyl ester, 3-methyl-1-butanol-acetate, ethyl hexanoate, ethyl octanoate, acetic acid 2-phenylethyl ester, and ethyl lactate; concentrations of 3-methyl-butanoic acid, propanoic acid, acetic acid, and butanoic acid were low. The CSP cheese had stronger acid-producing ability. The order of fragrance production performance was CSS > CSI, CSM > CSP > CS. Research into the fermentation mechanisms of GABA-producing yeast in cheese will provide a theoretical basis for the quality control and industrial production of Kazakh cheese.

The Prospects of Lactobacillus oris as a Potential Probiotic With Cholesterol-Reducing Property From Mother's Milk

This experiment was conducted to characterize potential Lactobacillus spp. isolated from mother's milk and infant feces to obtain new and specific probiotic strains. In this study, seven ascendant strains were identified as Lactobacillus spp. based on their morphological characteristics and biochemical properties. Among them, only one (C-1) isolate was identified as Lactobacillus oris through BioLog^TM identification. The study further investigated the isolate through probiotic potentiality tests such as pH and bile tolerance, NaCl tolerance test, gastric juice tolerance, antioxidant activity, resistance to hydrogen, reduction of sodium nitrate, antimicrobial activity, and antibiotic susceptibility test. The result showed that the strain is a potential probiotic based on probiotic capability. The identified strain was most acid-tolerant and retained around 80% viability for up to 4 h at pH 1.0 and 2.0. The isolate showed tolerance against up to 1.50% bile concentration and gastric juice and was able to grow 1-6% NaCl concentrations. Lactobacillus oris showed resistance to most antibiotics as well as antagonistic activity against the tested pathogen, good antioxidant properties, reduction of sodium nitrate and H₂O₂. The isolate exhibited good intestinal epithelial adhesion properties, and SDS page was performed for secreted protein analysis. Moreover, the strain showed promising cholesterol-lowering properties based on the cholesterol level. This present result indicates that L. oris has superior probiotic properties and can be regarded as a potential probiotic candidate.

Characterization of Sporidiobolus ruineniae A45.2 Cultivated in Tannin Substrate for Use as a Potential Multifunctional Probiotic Yeast in Aquaculture

At present, few yeast species have been evaluated for their beneficial capabilities as probiotics. Sporidiobolus ruineniae A45.2, a carotenoid-producing yeast, was able to co-produce cell-associated tannase (CAT), gallic acid and viable cells with antioxidant activity when grown in a tannic acid substrate. The aim of this research study was to identify the potential uses of S. ruineniae A45.2 obtained from a co-production system as a potential feed additive for aquaculture. S. ruineniae A45.2 and its CAT displayed high tolerance in pH 2.0, pepsin, bile salts and pancreatin. Furthermore, its viable cells were characterized by moderate hydrophobicity, high auto-aggregation and moderate co-aggregation with Staphylococcus aureus, Salmonella ser. Thyphimurium and Streptococcus agalactiae. These attributes promoted S. ruineniae A45.2 as a multifunctional probiotic yeast. In addition, the intact cells possessed antioxidant activities in a 100–150 μg gallic acid equivalent (GAE)/mL culture. Remarkably, the fermentation broth demonstrated higher antioxidant activity of 9.2 ± 1.8, 9.0 ± 0.9, and 9.8 ± 0.7 mg GAE/mL culture after FRAP, DPPH and ABTS assays, respectively. Furthermore, higher antimicrobial activity was observed against Bacillus cereus, Staphylococcus aureus and Strep. agalactiae. Therefore, cultivation of S. ruineniae A45.2 with a tannic acid substrate displayed significant potential as an effective multifunctional feed additive.

Autogenic successions of bacteria and fungi in kefir grains from different origins when sub-cultured in goat milk

Kefir grains are a unique symbiotic association of different microbiota, including a variety of bacterial and fungal species. The microbiota in kefir grains is strongly influenced by the geographical origin and sub-culturing environment. After sub-culturing in goat milk for 2 to 4 months, amplicon sequencing (16S rRNA and ITS1 region) was applied for the identification of bacterial and fungal autogenic succession of three kefir grains collected from China (CN, Asia), Germany (DE, Europe) and United States of America (USA, America). Taxonomic analysis displayed three main bacterial and fungal species in kefir grains from different origins during sub-culturing process (Lactobacillus helveticus, Lactobacillus kefiranofaciens and Lactobacillus kefiri for bacteria, Kazachstania unispora, Kluyveromyces marxianus and Saccharomyces cerevisiae for fungi). Based on the results of beta diversity analysis, microbiota in kefir grains from CN and DE would be stable when sub-cultured in goat milk for more than three months. Differently, a highly microbial stability has been found for the sample from USA during the whole sub-culturing process. These results helped to understand the composition and stability of microbiota in kefir grains when sub-cultured in goat milk.

Effects of kefir grains from different origins on proteolysis and volatile profile of goat milk kefir

Microbial diversity in kefir grains is responsible for the production of goat milk kefir with unique peptides composition and volatile profile. High-throughput sequencing technique was used to analyze bacterial and fungal diversity of three different kefir grains which were originated from China, Europe Germany and United States. Peptides and volatile profile in goat milk kefir were determined by proteomic platform and Gas Chromatography-Ion Mobility Spectrometry, respectively. Clustering analysis indicated that the different content of Lactobacillus genera in different kefir grains was highly associated with the proteolytic ability in goat milk kefir. Contents of volatile compounds in goat milk kefir were also correlated to the bacteria and fungi in kefir grains (especially for Lactobacillus spp. and Saccharomyces spp.). The innovation of this study was to find a new way in exploration of the correlation of microbiota in kefir grains with the proteolytic ability and volatile profile of goat milk kefir.

A new practical approach for the biological treatment of a mixture of cheese whey and white wastewaters using Kefir grains

Kefir grains are a microbial consortium of different genera of bacteria and yeasts. In this study, the performance of Tunisian Kefir grains during the biological treatment of a mixture of Gouda cheese whey and white wastewaters (GCW) in ratio 1:1 with very high organic matter concentration is investigated. The biological process was evaluated and optimized through the response surface methodology. Under the optimum conditions, Kefir grains concentration of 1.02%, temperature at 36.68 °C, and incubation time of 5.14 days, the removal efficiencies of COD, PO₄^3-, and NO₃^- were 87, 37.48, and 39.5%, respectively. Interestingly, the reusability tests of the grains proved not only their high resistance to harsh environmental conditions but also their great potential for more practical applications. Particularly, different strains were isolated from the grains and identified as Kluyveromyces marxianus, Lactoccocus lactis, Lactobacillus kefiri, and Bacillus spp. using 16S rDNA sequence analysis and rep-PCR fingerprinting. At the biological level, the raw GCW (RGCW) has a negative impact on the Hordeum vulgare both on seed germination, and on the growth parameters of seedlings. Interestingly, after Kefir grains treatment, the treated GCW (TGCW) allow a seedlings growth and germination rate similar to those soaked in water.