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A chitosan-glucose derivative (ChG) with lower antimicrobial activity against whey native probiotic yeast K. marxianus VM004 was synthesized by the Maillard reaction. The ChG derivative was characterized by FT-IR, 1H NMR, and SLS to determine the structure, deacetylation degree (DD), and molecular weight (Mw). In addition, we evaluated the antioxidant, cytotoxic, and antimicrobial activities of ChG. ChG was then used for microencapsulation of K. marxianus VM004 by spray drying. The microcapsules were characterized by evaluating their encapsulation yield, encapsulation efficiency, morphology, tolerance to the gastrointestinal tract, and viability during storage. The results indicated that a non-cytotoxic product with lower MW and DD and higher antioxidant activity than native chitosan was obtained by the Maillard reaction. The yeast ChG microcapsules exhibited an encapsulation efficiency >57 %, improved resistance to gastrointestinal conditions, and enhanced stability during storage. These results demonstrate that ChG may be a promising wall material for the microencapsulation of probiotic yeasts.

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Antibiotic bacterial resistant is a huge concern worldwide and probiotics offer an alternative to mitigate it. This study explores Cystobasidium benthicum LR192 as possible probiotic through microbiological and immunological analyses in mouse model. C. benthicum LR192 was isolated from lichens in a hyperarid environment in Baja California Sur, Mexico. First, microbiological analysis was assessed using 1 × 105 CFU/mL in YM broth: resistance to 1% of bile salts and pH of 2, 3 and 5 (control). Then, yeast capacity to adhere onto the intestinal mucosa and safety to mouse splenocytes were tested. Finally, immunological parameters (phagocytic ability, respiratory burst and myeloperoxidase activities, nitric oxide and IgG production) and immune-associated gene expression (IL-1ß, IL-6 and INF-γ) were determined in daily supplemented mice with the yeast (1 × 108 CFU) at days 10 and 15. The results indicate that C. benthicum LR192 has medium resistance to bile salts and low pH, can adhere to the intestine and did not cause cytotoxicity in splenocytes. Immune parameters and immune-related gene expression indicated immunomodulation at day 10 and 15, specially in leucocytes challenged with Escherichia coli. In conclusion, C. benthicum LR192 showed safe potential probiotic properties, but further studies should be performed to confirm it as a probiotic prospect for humans.

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The production of biomolecules using agro-industrial by-products as feedstock is a growing trend worldwide. Selenium (Se) is a trace element essential for health, and the Se-enrichment of yeast biomass can enhance its benefits. This study investigated the feasibility of the production of Saccharomyces cerevisiae Se-enriched biomass using a medium composed of corn bran and soybean bran acid hydrolysates as carbon and nitrogen sources in a stirred-tank reactor. After hydrolysis, hydrolysates presented complex composition and high concentrations of sugars, proteins, and minerals. The use of a stirred-tank bioreactor leads to the production of 9 g/L S. cerevisiae biomass enriched with 236.93 µg/g Se, and 99% cell viability. Likewise, the combination of sugarcane molasses and soybean bran hydrolysate was effective for cell growth of a probiotic strain of S. cerevisiae with a 24.08% ß-glucan content. The results demonstrated that starchy acid hydrolysates are low-cost and efficient substrates for the production of yeast biomass and derivate products and may contribute to further studies for a sustainable development of biorefinery technologies.

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The immunostimulatory potential of the marine yeast Yarrowia lipolytica (D1 and N6 strains) administered orally was evaluated in the white shrimp Litopenaeus vannamei. Yeasts and commercial glucans were mixed with a commercial feed to formulate diets with a 1.1% concentration of immunostimulants. The shrimp were fed daily for a period of 21 days. Weekly determinations were performed for immunological parameters in hemolymph, such as total hemocyte count (THC), lysozyme activity (LYZ), prophenoloxidase activity, antioxidant enzymatic activities (superoxide dismutase [SOD], catalase [CAT], and peroxidases), and bactericidal activity against Vibrio parahaemolyticus. Expression profiles of penaeidin (PEN), lysozyme (LYZ), and prophenoloxidase (proPO) immune genes were evaluated in hemocytes. In general, an increase in the immune parameters was observed in shrimp fed yeast diet compared to glucan and the control diets. Yarrowia lipolytica, especially strain N6, provided maximum immunostimulatory effects evidenced by the increase of immune parameters (THC, LYZ, SOD, CAT) and gene expression profile. In conclusion, this study demonstrated that Y. lipolytica had immunostimulatory effects and increased bactericidal activity in L. vannamei hemocytes against V. parahaemolyticus. These findings open the path for the potential application of Y. lipolytica-based immunostimulant for shrimp aquaculture.

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Artisanal fermented beverages have been associated with beneficial effects for a long time. In Mexico, there are a wide variety of artisanal fermented beverages such as Tepache, where the fermentation is initiated by the addition of grains of a polysaccharide-containing biofilm matrix formed by a symbiotic association of bacteria and yeasts known as "Tibicos." These microorganisms can be responsible for the beneficial effect associated with fermented beverages inoculated with Tibicos. The probiotic potential of microorganisms has been widely studied, mainly in lactic acid bacteria, while despite the wide distribution of yeasts, these have not been so studied. Therefore, the aim of this study was to evaluate in vitro the probiotic potential properties of a yeast isolated from Tibicos. For this, the yeast was identified by molecular techniques as Saccharomyces cerevisiae, which showed a good resistance to pH 2.0, bile salts and in vitro digestion. The results also showed a good ability to form cellular aggregates as a result of having a hydrophobic surface. In addition, it can be considered as safe since it does not show hemolytic activity and is sensitive to nystatin. Additionally, the yeast presented an excellent antioxidant capacity to reduce the DPPH radical. The S. cerevisiae strain C41 isolated from Tibicos was successfully compared by means of in vitro tests with the only recognized probiotic yeast, S. boulardii. These findings point Saccharomyces cerevisiae C41 as a potentially probiotic yeast; nevertheless, it is necessary to consider further in vitro and in vivo studies that establish the benefits that this yeast could provide.

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Probiotics represents an alternative to replace antibiotics as growth promoters in animal feed and are able to control enteric bacterial diseases and to improve gut immunity. Saccharomyces cerevisiae RC016 showed previously inhibition/coagregation of pathogens) and mycotoxins adsorbent ability (aflatoxin B1, ochratoxin A and zearalenone). The aim of this work was to evaluate beneficial properties of S. cerevisiae RC016 in a non-inflammatory in vivo model in weaned piglets and in an intestinal inflammation ex vivo model induced by the mycotoxin deoxynivalenol (DON). Secretory immunoglobulin A (s-IgA) levels, intestinal cytokines, goblet cells and production parameters were evaluated in a pig model. For the in vivo assays, twelve pigs were weaned at 21 days and assigned to two groups: Control (n=6) and Yeast (n=6). Animals received yeast strain for three weeks. After 22 days the small intestine was recovered for determination of goblet cells and s-IgA. For the ex vivo assay, jejunal explants were obtained from 5 weeks old crossbred piglets and treated as follow: (1) control; (2) treated for 3 h with 10 µM DON used as an inflammatory stressor; (3) incubated with 107 cfu/ml yeast strain; (4) pre-incubated 1 h with 107 cfu/ml yeast strain and then treated for 3 h with 10 µM DON. CCL20, interleukin (IL)-1ß, IL-8 and IL-22 gene expression was determined by qPCR. Oral administration of S. cerevisiae RC016 increased s-IgA, the number of goblet cells in small intestine and all the growth parameters measured. In the ex vivo model, the cytokine profile studied showed a potential anti-inflammatory effect of the administration of the yeast. In conclusion, S. cerevisiae RC016 is a promising candidate for feed additives formulation to improve animal growth and gut immune system. This yeast strain could be able to improve the gut health through counteracting the weaning-associated intestinal inflammation in piglets.

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Inflammatory bowel diseases (IBDs) are complex affections with increasing incidence worldwide. Multiple factors are involved in the development and maintenance of the symptoms including enhanced oxidative stress in intestinal mucosa. The conventional therapeutic approaches for IBDs are based on the use anti-inflammatory drugs with important collateral effects and partial efficacy. In the present work we tested the anti-inflammatory capacity of Kluyveromyces marxianus CIDCA 8154 in different models. In vitro, we showed that the pretreatment of epithelial cells with the yeast reduce the levels of intracellular reactive oxygen species. Furthermore, in a murine model of trinitro benzene sulfonic acid-induced colitis, yeast-treated animals showed a reduced histopathological score (P<0.05) and lower levels of circulating interleukin 6 (P<0.05). The capacity to modulate oxidative stress in vivo was assessed using a Caenorhabditis elegans model. The yeast was able to protect the nematodes from oxidative stress by modulating the SKN-1 transcription factor trough the DAF-2 pathway. These results indicate that K. marxianus CIDCA 8154 could control the intestinal inflammation and cellular oxidative stress. Deciphering the mechanisms of action of different probiotics might be useful for the rational formulation of polymicrobial products containing microorganisms targeting different anti-inflammatory pathways.

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