Continue to hypothesize that honey is a storehouse of beneficial bacteria, and the majority of these isolates are levansucrase producers. Accordingly, ten bacterial strains were isolated from different honey sources. Four honey isolates that had the highest levansucrase production and levan yield were identified by the partial sequencing of the 16S rRNA gene as Achromobacter sp. (10A), Bacillus paralicheniformis (2M), Bacillus subtilis (9A), and Bacillus paranthracis (13M). The cytotoxicity of the selected isolates showed negative blood hemolysis. Also, they are sensitive to the tested antibiotics (Amoxicillin + Flucloxacillin, Ampicillin, Gentamicin, Benzathine benzylpenicillin, Epicephin, Vancomycin, Amikacin, and Zinol). The isolates had strong alkaline stability (pHs 9, 11) and were resistant to severe acidic conditions (29–100 percent). The tested isolates recorded complete tolerance to both H2O2 and the bile salt (0.3% Oxgall powder) after 24 h incubation. The cell-free supernatant of the examined strains had antifungal activities against C. Albicans with varying degrees. Also, isolates 2M and 13M showed strong activities against S. aureus. The isolates showed strong adhesion and auto-aggregation capacity. Isolate 10A showed the highest antioxidant activity (91.45%) followed by 2M (47.37%). The isolates recorded different catalase and protease activity. All isolates produced cholesterol oxidase and lipase with different levels. Besides, the four isolates reduced LDL (low-density lipoprotein) to different significant values. The cholesterol-reducing ability varied not only for strains but also for the time of incubation. The previous results recommended these isolates be used safely in solving the LDL problem.

T WENTY-THREE different bacterial and fungal isolates were grown and screened for their capability to transform soy glycosides to their aglycone forms with higher titer of antioxidant activity compared to unfermented soy flour. Most of the bacterial isolates showed higher amounts of daidzein than of genistein, which are the aglycone products of daidzin and genistin. After fermentation of soybean flour using bacterial and fungal isolates, the content of isoflavone aglycones varied from 0.0 to 431.89 µg/g compared to unfermented autoclaved soybean flour. Extracellular β-glucosidase activity was ranged from 1.22 to 11.56 mU/mL and 0.3-534.3 U/mL for bacterial and fungal isolates, respectively, while, bacterial cell-bound β-glucosidase ranged from 44.72 to 128.89 mU/mL. Most of the bacterial isolates more efficiently transformed daidzin and genistin into the aglycones than fungal isolates. Among the tested bacterial isolates, the most potent one was selected, characterized according to the morphological and 16S rDNA sequence analysis and identified as Bacillus licheniformis NRC24.

Background and objective Fermented soy products were regarded as healthy foods and hence are considered an essential part of the diet. Lactic acid bacteria isolated from naturally fermented Egyptian food products were screened for their ability to produce β-glucosidase, isoflavone aglycone, phenolics, and antioxidant activity during the formation of soy yogurt. The present research is a preliminary attempt to ascertain soy yogurt production by different strains of lactic acid bacteria and their efficacy for the production of the aforementioned products. Materials and methods A total of 16 probiotic lactic acid bacteria were used for the preparation of soy yogurt and tested for their probiotic properties. Soymilk was prepared and inoculated (1% v/v) with the probiotic strains previously activated in the MRS medium. After fermentation, cell viability, pH, titratable acidity, total phenolic compounds concentration, antioxidant activity, isoflavones aglycone (daidzein and genistein), and extracellular and cell membrane-bound β-glucosidase activity were determined. Results and conclusion A total of 16 probiotic lactic acid bacteria were used for the preparation of soy yogurt. The final pH of the fermented soymilk ranged from 4.92 to 6.6, and their titratable acidity (lactic acid %) ranged from 0.5 to 0.99%. Changes in β-glucosidase, isoflavone aglycone, total phenolics content, and antioxidant activity during the formation of soy yogurt were determined. All bacterial isolates showed positive cell-bound and extracellular β-glucosidase. Their activities ranged from 308.65 to 553 mU/ml. The Lactobacillus strains showed lower extracellular than their cell-bound β-glucosidase, and the opposite was true for the other group. An increase in the content of isoflavone aglycones in soy yogurt could be achieved by aging with bacterial fermentation. Soymilk fermented with Lactobacillus strains showed the highest bioconversion of isoflavone glucosides into isoflavone aglycones than other strains, although they produced less β-glucosidase enzymes. The antioxidant activity is related to changes in total phenolics. All microorganisms were able to increase the total phenols, whereas some Lactobacillus strains were unable to release more phenols compared with unfermented soymilk.

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

The submerged fermentation parameters of defatted soybean flour with Bacillus licheniformis NRC24 were optimized using the one-factor at-a-time method and Box-Behnken design to maximize the production of β-glucosidase and transformation of glucosidic isoflavones (daidzin and genistin) into their aglycones. One-factor-at-a-time optimization studies revealed that 80 g/L of defatted soybean flour , fermentation time of 16 h, temperature at 37°C, initial pH value of 7, inoculum volume of 5% (6x107 CFU/mL), and medium volume of 50 mL in 250 mL Erlenmeyer flask with shaking conditions at 100 rpm were the most suitable conditions for aglycones production. The addition of cellobiose (1 percent w/v) to the soy flour medium resulted in a significantly increase in total aglycone. Further optimization using the Box-Behnken design resulted in a 1.11-fold increase in daidzein and genistein. Antiviral activity was observed against the (H5N1) influenza, herpes simplex type 1, and rota virus. The MTT cytotoxicity assay of the extract using MDCK, Vero, and MA104 cell lines revealed that fermented soybean flour reduced cytotoxicity more than the unfermented one. However, it showed higher cytotoxicity against HCT-116 colon cancer cells, MCF-7 breast and PC3 prostate cancer cells than the unfermented soy extract.