Antibacterial activity of two actinomycetes species isolated from black sand in North Egypt

Abstract

Increasingly high levels of multidrug-resistant (MDR) pathogens have necessitated the discovery of novel bioactive compounds. For this reason, two actinomycetes strains, Streptomyces griseorubens and Streptomyces rochei, were isolated for the first time from the black sand shores of Kafr El Sheikh in Egypt, which is home to several large fish farms. Isolates were identified via phenotypic, biochemical and 16S rRNA sequence protocols. Both strains exhibited powerful antimicrobial activity against three serious MDR pathogens: Bacillus subtilis, Salmonella enteritidis and Pseudomonas aeruginosa. The bioactive compounds of isolates’ filtrates were identified using gas chromatography–mass spectroscopy (GC-MS). For S. griseorubens, the detectable antibacterial compounds were hexanoic acid, 2-ethyl-, 2-ethylhexyl ester, n-Decane, hexadecanoic acid methyl ester, benzene acetic acid, ricinolic acid, and ethylparaben, while S. rochei secretes heptadecane, 2,6-dimethyl-, benzene acetic acid, dibutyl phthalate, octacosane, hexacosane, and vitamin A aldehyde. These results strongly encourage the use of these eco-friendly isolates as a biocontrol against MDR pathogens that attack fish farms. Significance: Streptomyces spp. act as strong weapons for fighting multidrug resistance in pathogenic bacteria – one of the most important current threats to public health. They are additionally regarded as eco-friendly organisms that can be used as a biocontrol agent against infections that endanger fish farms.