Bioactive compounds of the Actinomycetes isolated from Garmsar Saline River, Iran

Abstract

Saline environments are unique ecosystems that harbor novel bacterial species with the potential to produce valuable secondary metabolites. In the present study, 26 actinomycetes strains were recovered predominantly from the rhizosphere (81%), in addition to sediments and water samples collected from four sites along the Garmsar Saline River in Iran. According to phylogenetic analysis, the isolated strains were identified as belonging to two different genera: Streptomyces, and Nocardiopsis. Several of the isolated actinomycetes exhibited valuable biotechnological potential, producing a diversity of enzymes including amylase, gelatinase, protease, lipase, lecithinase, and laccase. Inhibitory effects on the growth of human tumor cells were also observed; the extract of strain M15 displayed notable cytotoxicity against MCF7 human breast cancer cells with an IC50 value of 32.81 µg/ml. Also, 59% of the strains had antibacterial activity against some pathogenic and non-pathogenic test strains. Ethyl acetate extracts of the selected actinomycetes were screened, and strain M16 was found to exhibit the most potent inhibitory effect on Proteus mirabilis. GC/MS analysis of M16’s extract revealed it mainly consisted of 1,2-benzenedicarboxylic acid, bis(2-methylpropyl) ester (16.61%), and 9-octadecenamide (12.77%). Based on 16S rRNA sequence analysis, Strain M16 showed the highest similarity to Nocardia aegyptia. The study concludes that actinomycetes from the Garmsar Saline River possess considerable potential for biotechnological application.