Thesis (M.Sc)-Cairo University, 2025.

Bibliography: pages 111-140.

This study was designed to characterize the probiotic potential of a novel strains isolated
from Egyptian human´s and cow´s milk, both of which are considered rich sources of beneficial
bacteria, and to explore the biotechnological applications of those isolates. Hence, A total of 40
human and cow milk samples were collected manually, Isolation and identification were
conducted. The isolates were evaluated for key probiotic attributes, including antimicrobial
activity, simulated gastric juice resistance, and safety assessment. Based on the 16S rRNA
sequence; isolates C3, C7, and H9 were identified as Enterococcus durans while, C10 and H5 were
identified as Enterococcus hirae. On the other hand, C1, H1, and H7 were identified as
Enterococcus faecium and C12, H12 were Lactococcus lactis. Furthermore, C4, C8, H2, and H14
were identified as Pediococcus pentosaceus, Lacticaseibacillus rhamnosus, Enterococcus
mundtii, and Enterococcus lactis, respectively. All strains exhibited high rates of survival in
simulated gastrointestinal fluids, resist to lysozyme and were able to assimilate cholesterol
ranging from 21.35 to 38.50%. Antagonistic assay demonstrated that all strainsexhibited strong
inhibitory activity against pathogenic bacteria supporting its potential as a probiotic with
antimicrobial properties. Isolates from cow milk demonstrated significant tolerance during cold
storage especially Enterococcus faecium strain C1, Enterococcus durans strain C3, and
Lacticaseibacillus rhamnosus strain C8. Cold storage resistance experiment revealed
Enterococcus faecium C1, Enterococcus duransC3, and Lacticaseibacillus rhamnosus C8
effectively survival throughout the storage, highlighting its potential for functional dairy
applications as a novel starter culture and co- culture. Thus, nine formulations of a fermented
whey mango beverage were carried out and compared to non fermented whey supplemented
with mango juice. No significant differences (p ≥ 0.05) were observed in the chemical
composition; whereas significant differences (p ≤ 0.05) were in pH. Concentration of total
phenolic content was ranged from (51 to 125.02 mg GAE/g), while antioxidant activity was
significantly increased in fermented whey beverages by C3 strain (86.7%) compared to control
sample (60.52%). Organic acid metabolites especially lactic and acetic acids were present in
large amounts in all the fermented whey samples. Furthermore, the fermented whey mango
beverages provided a favorable environment for the growth of probiotic bacteria; the bacterial
count during the storage period exceeded 7 logs CFU/ml, which was significantly higher than
the minimum therapeutic dose. Sensorially, the addition of probiotic strains C4, C8, H7 and H9
significantly (p ≤ 0.05) improved the final product's structural qualities, color and sensory
acceptance. These findings collectively suggest that Enterococcus faecium strain C1,
Lacticaseibacillus rhamnosus strain C8, Enterococcus mundtii strain H2 and Enterococcus hirae
strain H10 possesses desirable probiotic characteristics. Additionally, utilization of different
LAB isolates from either human or cow milk with adding fruits to whey supplements could be
a viable alternative for creating nutritious whey beverages and could be recommended for
consumption.

تم في هذه الدراسة عزل 27 سلالة بكتيرية من لبن الأم واللبن البقري المصري، وتم تعريف أربع عشرة عزلة منها باستخدام تقنية التسلسل الجيني لجين 16S rRNA. تم التأكد من أمان وسلامة هذه العزلات، ثم تقييم خصائصها الداعمة للحيوية. وقد أظهرت النتائج أن السلالات المختبرة تمتلك خصائص حيوية واعدة، ومن ثم تم اختيار تسع سلالات بكتيرية متميزة لاستخدامها في إنتاج تسعة مشروبات وظيفية قائمة على شرش المانجو.
تم إجراء اختبارات حسية، وكيميائية، وميكروبيولوجية على هذه المشروبات، و أظهرت النتائج قبولًا حسيًا مرتفعًا، بالإضافة إلى احتوائها على نسب عالية من المركبات الفينولية ومضادات الأكسدة. كما أثبتت معظم السلالات قدرة جيدة على البقاء والنمو داخل المشروبات أثناء فترة التخزين لمدة عشرة أيام.

Issues also as CD.

Text in English and abstract in Arabic & English.