Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Botany - Microbiology

The actinobacterial strain Streptomyces candidus proved as a promising source for the biosynthesis of new secondary metabolites. The seventh fermentation day was selected for the purification by using the column chromatography; mixture of ethyl acetate and n-butanol in different ratios were used to collect eleven fractions (FI-FXI). Thirty metabolites were detected in only four fractions by using the GC-MS. The seven aliphatic compounds of FI were successfully chemically modified to seven heterocyclic compounds by the one pot reaction. The semi-synthesized compounds (148 to 208 nm) converted to the nano-size (1.92 to < 20 nm); then evaluated for their MIC and cytotoxic effect. They more sensitive against the S. aureus and L. Monocytogenes (6.25oL); while less sensitive against E. coli and S. typhimurium (50oL) for their MIC. The compounds found non-toxic by using the Artemia salina nauplii assay development; the LC50was equal to the 67.6 oL (< 1000 og\ml)

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