Abstract

Most actinomycete species have the capability to synthesize many different biologically active secondary metabolites such as antibiotics, herbicides, pesticides, anti-parasitic and enzyme inhibitors. The main focus of the present study was to isolate some new actinobacterial strains from the Saudi habitats and study the biological effects of their secondary metabolites on the heart development of the zebra fish embryos as a drug discovery screening model. For this purpose, 6 soil samples were collected and 100 strains were isolated. Out of the isolated strains, 5 isolates were selected for extraction and screening based on differences in morphological appearance. The selected strains were characterized morphologically to confirm that they belong to actinobacteria. All of them were Gram-positive and rod or spherical in shape with variable lengths or diameters and arrangements. Most of the extracts induced abnormalities in the developing heart in zebra fish embryos on a dose dependent manner if exposed to sublethal concentrations (less than 20 µg/ml) of these extracts. The embryos exposed to the extracts had cardiac edema with enlarged cardiac chamber (cardiac hypertrophy). Some extracts also induced teratogenecity in developing brain. While on the other hand, some extracts even at higher concentration did not induce any significant abnormalities in developing zebra fish embryos. The current study highlights the significance of the biomedical applications of the actinobacteria isolated from the Saudi habitats.

Keywords: Actinobacteria, extracts, developmental effects, heart, zebra fish.