Biomedicine

Abstract

Introduction and Aim: There are centers for antibiotics in the nature to treat disease by looking for different sources, for example, actinomycetes, are approximately two-thirds of naturally occurring antibiotics, having much of medical importance, have been isolated from actinomycetes. The aim of the present study was to isolate and to identify the actinomycetes having antagonistic activity.
Materials and Methods: An actinomycetes strain isolated from dam soil sample collected from Alnajl dam of Hadhramout Yemen, showed antibacterial activity against selected microbial pathogens. The nutritional requirements and cultural conditions for maximal growth to produce secondary metabolites have been optimized under shake flask conditions. The growth and production of secondary metabolites were maximal with the use of SCA medium supplemented at pH 7.0, and incubation temperature and time of 37℃ and 20 days respectively.
Results: Based on morphological, biochemical, physiological and phylogenetic characterization, the strain was identified as Actinoplanes digitatisDnj-2 (MN567713). The ethyl acetate extract (1g/mL) obtained from the isolate showed significant antibacterial activity against Gram-negative bacteria- Escherichia coli (21 cm) and Pseudomonas aeruginosa (29 cm) and Gram-positive bacteria- Bacillus subtitles (31 cm) and Staphylococcus aureus (22 cm) when compared with penicillin G 10 units.
Conclusion: In conclusion, the isolated strain has broad spectrum of antagonistic activity against Gram-positive and Gram-negative bacteria.