الفهرس 
1. IntroductionOnly 14 pages are availabe for public view
Abstract
Pure colonies of twenty-three bacterial and fungal isolates were isolated from different Egyptian soil locations and were cultivated on media containing defatted soybean flour or cellobiose as a source of beta-glycosides and to test their capabilities to produce β-glucosidase.
All fungal isolates produced more extracellular β-glucosidases than those obtained by bacterial isolates during soybean flour fermentation.
All bacterial isolates showed positive cell-bound β-glucosidase activity.
Soybean flour fermented by the tested bacterial isolates resulted in a higher transformation of daidzin and genistin into daidzein and genistein, while that fermented by the tested fungal isolates could not perform the transformation except fungal isolates No. 5, 10 and 11 which had the capability to transfom only daidzin into daidzein.
Fermentation of defatted soybean flour by all bacterial and fungal isolates showed higher DPPH radical-scavenging activity in comparing to that of unfermented soybean flour.
Substrate specificity of the produced β- glucosidase was affected on the transformation of daidzin and genistin.
Out of twenty-three microbial isolates, two bacterial isolates could efficiently transform soy glucosides into their aglycone forms as they produced β-glucosidases with higher specificity to hydrolyze daidzin and genistin β-glycosidic bonds than those produced by the other tested microbial isolates. The methanolic extracts of the fermented soy flour using the two bacterial isolates showed an increase in antioxidant activities.
Bacterial isolate No. 3 showed an efficient potency at different concentrations of soybean flour in transforming daidzin and genistin into their aglycone forms other than the tested bacterial isolate No. 8. For this reason, bacterial isolate No. 3 was selected as the working isolate of soy isoflavone glucosides transformation.
On the basis of morphological characteristics and 16S rDNA sequence analysis, the bacterial isolate No.3 was identified as B. licheniformis NRC24.
Nutritional and environmental conditions for soy glucosides transformation were studied using B. licheniformis NRC24. Of different defatted soybean flour concentrations, maximum glucosides transformation was recorded at 80 g/L.
Maximum level of transformed aglycones was achieved using B. licheniformis NRC24 with optimum fermentation time of 16 hr., fermentation temperature of 370C, initial pH value of 7, inoculum volume of (5%) from cell suspension (6×107 CFU/mL), and with a culture volume of 50 mL in 250 mL Erlenmeyer flasks under shaking conditions at 100 rpm
Adding (1% w/v) cellobiose showed a notably greater increase in aglycones in compared to plain fermented soybean flour.
By applying Box-Behnken design with three variables namely; defatted soybean flour concentration, incubation time and medium volume. The statistical data of the experiment proved that there was a critical limit for stimulation of glucosides transformation by those variables. The results also proved that the applied design was effective for optimizing the transformation of daidzin and genistin as their total aglycones was increased by 1.11-fold.
Fermented and unfermented soybean flour extracts were tested for their, in vitro, antibacterial, antifungal, antiviral activities and cytotoxicity.
Fermented soybean flour extract showed antiviral effect against A/chicken/ Egypt/ M7217B/1/2013 (H5N1) Influenza virus, herpes simplex virus type 1 and rotavirus than that obtained by unfermented soybean flour extract.
Fermented and unfermented soybean flour extracts showed no antibacterial activity toward the tested bacterial strains (Staphyllococcus aureus ATCC6538, Klebsiella pneuomonia ATCC10031, Salmonella typhimurium ATCC14028, Escherichia coli ATCC25922, Proteus mirabillus ATTC9240, B. subtilis and B. cereus).
Fermented and unfermented soybean flour extracts showed antifugal activity against Fusarium solani, while both extracts did not exhibited activity against Candida albicans (ATTC10231), Rhizopus oryzae, Trichoderma longibrachiatum and Aspergillus niger.
MTT cytotoxicity assay of both fermented and unfermented extracts using MDCK, Vero and MA104 cell lines showed that fermentation of soybean flour by B. licheniformis NRC24 had lesser cytotoxicity against MDCK and MA104 cell lines than unfermented soybean flour extract.
Cancer cell lines, colon HCT-116 cells, breast MCF-7 cells and prostate cancer PC3 cells were treated with unfermented and fermented soy flour extracts and the cells proliferation was investigated by MTT assay. As a result, fermented soy flour extract showed higher cytotoxicity against the tested cells than unfermented soy flour extract.