Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

There is a rising interest in the role that honey bees microbiome might play in the contribution to honey beneficial properties. Honey harbors only microorganisms with unique characteristics that are able to survive in its harsh nature such as spore forming organisms. The bioactive compounds produced by them or transferred from bee gut confers to the honey benefits. Some members of these bacteria are levansucrase producers, a fructosyltransferase enzyme that produces levan polysaccharide a known prebiotic with impressive benefits to the host. In this work, several phenotypic and molecular approaches were used to investigate possible relatedness or variations in levansucrase from honey and honey bee isolates and their associated probiotic and prebiotic effects, genes and protein sequences. Five bacterial isolates from honey samples and bees guts were selected based on high activity of levansucrase and levan yield. All isolates showed tolerance to temperature up to 70 {u00B0}C, to NaCl up to 3 M and to 0.1% H2O2.They retained over 59% and 64% survival at pH 9.0 and 2.0, respectively, but showed variable tolerance to 0.1% bile salts and pancreatic enzymes. Most isolates were susceptible to a wide range of antibiotics and demonstrated diverse antimicrobial activity. Non hemolytic isolates were identified based on their 16S rRNA sequencing and PCR amplification of ytcP gene as Bacillus subtilis HMNig-2 from honey and Bacillus subtilis MENO2 from honey bee

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