This study focuses on the exploration of bioactive compounds from the brown
macroalgae Padina pavonica collected from the deep-sea waters of Hurghada, Red Sea,
Egypt. The distinct morphological features of Padina pavonica, including slender, foliate, and
planar fronds in the young stage, and increased thickness with a concave form in mature
fronds, were characterized. Delicate hairs on external surfaces, slime-coated internal surfaces,
and sparse calcification with inward-curving edges further define this alga.
Endophytes, specifically twelve streptomyces strains, were isolated from the sterilized
surfaces of sponge and algae fragments collected from the Red Sea. Isolation techniques
involved immediate tagging and transportation to the laboratory, followed by storage in
sterile polyethylene bags at 4°C. Actinomycetes were isolated within 24 hours using a serial
dilution method based on distinct colony morphology and color variations. Purification was
achieved through repeated streaking on ISP-2 medium subculture plates, leading to the
isolation of strains coded as 36X, 37X, 38X, and 39X.
The subsequent fermentation of isolated actinomycetes on rice medium in Erlenmeyer
flasks yielded bioactive components. Ethyl acetate was employed for the extraction of crude
extracts, which were then subjected to antimicrobial screening using the agar disc diffusion
method. Isolate 36X exhibited significant antimicrobial activity, particularly against
Staphylococcus aureus and Pseudomonas aeruginosa. Isolate 37X displayed moderate activity
against both bacteria and fungi (Candida albicans and Aspergillus niger). Conversely, Isolates
38X and 39X did not exhibit significant antimicrobial activity. These findings highlight the
diverse antimicrobial capabilities of the isolated compounds, emphasizing the potential applications of Isolates 36X and 37X in combating infections caused by specific
microorganisms. Further research, including concentration variations and additional assay
methods, is essential to elucidate the specific bioactive components and unlock the
therapeutic potential of these isolates in medical and related fields.