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The study provides valuable insights into the sustainable utilization of edible tuber peels from the high mountains of the Argentinian Puna, which constitutes promising reserves of bioactive phenolic compounds with the potential to enhance the biofunctional properties of lactic acid bacteria. Thirty-two extracts derived from peels of different varieties of tubers, such as Oxalis tuberosa Mol., Ullucus tuberosus Caldas, and Solanum tuberosum L. were incorporated into lactobacilli cultures and individually evaluated. These selectively enhance the development of the probiotic strain Lactiplantibacillus plantarum ATCC 10241 and of Lacticaseibacillus paracasei CO1-LVP105 from ovine origin, without promoting the growth of a pathogenic bacteria set (Escherichia coli O157:H12 and ATCC 35218, Salmonella enterica serovar Typhimurium ATCC 14028, and S. corvalis SF2 and S. cerro SF16), in small amounts. To determine the main phenolic group concentrated in the phytoextracts, a bio-guided study was conducted. The most significant results were obtained by O. tuberosa phytochemicals added to the culture medium at 50 µg/mL, yielding promising increases in biofilm formation (78% for Lp. plantarum and 43% for L. paracasei) and biosurfactant activity (112% for CO1-LVP105 strain). These adaptive strategies developed by bacteria possess key biotechnological significance. Furthermore, the bio-detoxification capacity of phenol and o-phenyl phenol, particularly of the novel strain CO1-LVP105, along with its mode of action and genetic identification, is described for the first time to our knowledge. In conclusion, lactobacilli strains have potential as fermentation starters and natural products, recovered from O. tuberosa peels, and added into culture media contribute to multiple bacterial biotechnological applications in both health and the environment.

Fil: Nuñez, Ivana Micaela. Universidad Nacional de Tucumán. Instituto de Biotecnología Farmacéutica y Alimentaria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biotecnología Farmacéutica y Alimentaria; Argentina

The study aimed to evaluate the ability of dominant lactic acid bacteria (LAB) in orange juice to growth on N-depleted MRS medium supplemented or not with cysteine (mMRS), then to select the most nutritionally promising strains for growth assays in the food matrix and evaluation of beneficial attributes for fruit juice fermentation. Levilactobacillus brevis and Lactiplantibacillus plantarum were dominant species among the total of 103 LAB isolates as confirmed by multiplex PCR and/or 16 s rDNA sequence analysis. Based on growing lower than 20% and higher than 70% in mMRS (1.0 g/l meat extract, without peptone and yeast extract) with and without cysteine requirement, one L. brevis (JNB23) and two L. plantarum (JNB21 and JNB25) were selected. These bacteria and the L. plantarum strains N4 and N8 (previously isolated from oranges peel) when inoculated in orange juice grew up to 1.0 log cfu/ml for 24 h incubation at 30 °C and mainly produced lactic acid, with strains JNB25 and JNB23 reaching the highest and lowest cell densities in agreement with their nutritional exigency. In addition, all L. plantarum strains exhibited antagonistic activity against the majority of tested bacterial pathogens (in opposition to L. brevis), ability to grow or survive to pH 3.0 for 3 h, to grow with 0.5% sodium taurocholate, and a decrease after simulated gastrointestinal digestion assay which did not exceed 1.0 or 2.0 log units, depending on the strain. Thus, autochthonous L. plantarum strains with ability for overcoming nutritional limitations and beneficial attributes are promising candidates for further investigations as novel probiotic and/or preservative starters to ferment citric fruit juices.

Many probiotic products, with properly selected microorganisms, may not be effective for the intended purpose due to the low tolerance of microorganisms to gastrointestinal digestion. The microencapsulation seems to be one of the most promising techniques to protect probiotics against adverse environmental conditions. Therefore, the aim of this work was the design of soy protein isolate-alginate microcapsules for the encapsulation of probiotics for the poultry industry by the water-in-oil emulsion technique. To this end, the strain Ligilactobacillus salivarius CRL2217, with the ability to bind wheat germ agglutinin (WGA) on its surface and protect intestinal epithelial cells from the cytotoxicity of the glycoprotein, was used as model microorganism. Several parameters were varied in order to find the better conditions for microencapsulation: oil source and nature, SPI and sodium alginate concentration, stirring equipment and time for emulsion formation, CaCl2 concentration, and absence or presence of stirring after the addition of the CaCl2 solution. The survival of entrapped cells to a simulated gastric digestion and their survival and release during simulated intestinal digestion were also investigated. The obtained particles effectively protected L. salivarius CRL2217 from the proteolytic activity and low pH present in the gastric environment. Besides, their content was released in contact with a simulated intestinal juice, as viable counts and binding of WGA after a simulated intestinal digestion revealed. This work paves the way for the design of probiotic supplements for poultry including gastrointestinal digestion-susceptible bacteria.

Plant lectins, which are proteins/glycoproteins present in a wide range of vegetables, fruits, cereals and beans, are resistant to digestive enzymes and food cooking temperatures. They bind reversibly to specific glycosidic residues expressed on the membrane of intestinal epithelial cells (IEC) and cause anti-nutritional effects in humans and animals. Soybean lectin (SBA) has been detected in poultry diets, and its ability to bind to the intestinal epithelium has been reported. The development of new methods for removing SBA from feeds or to prevent interaction with the intestinal mucosa is of interest. In this study, the in vitro cytotoxicity of SBA on IEC of chicks was demonstrated for the first time. The LD50, assessed after 2 h exposure of IEC to SBA, was 6.13 μg mL−1. The ability of Bifidobacterium infantis CRL1395 to bind SBA on the bacterial envelope was confirmed, and prevention of IEC cytotoxicity by lectin removal was demonstrated. Safety of B. infantis CRL1395, resistance to gastrointestinal stress and adhesion were also determined. It was concluded that the early administration of B. infantis CRL1395 to chicks would effectively reduce the toxicity of SBA. Besides, it would favour the colonization of the gut with a beneficial microbiota. The cytotoxicity of soybean agglutinin on intestinal epithelial cells of broiler chicks is partially avoided by its capture by Bifidobacterium infantis CRL1395.