Molecular and Phenotypic Characterization of Novel Streptomyces Species Isolated from Kurdistan Soil and its Antibacterial Activity Against Human Pathogens

he global rise in antibiotic resistance has accelerated the search for novel antibiotics. Members of the Streptomycetaceae family produce more than 70% of clinically used antibiotics, prompting extensive research on the genus Streptomyces to discover new species capable of producing effective bioactive molecules against multidrug-resistant pathogens. This study aimed to investigate various soil sources from Kurdistan—including agricultural soil, house garden soil, cave soil, and petroleum-contaminated soil—for the presence of novel Streptomyces species harboring bioactive compounds.
Twenty soil samples were collected from these diverse environments. Selective media, combined with morphological characterization, biochemical testing, and molecular techniques, were employed for species identification. Out of the isolated bacteria, fifty-eight samples yielded positive PCR amplification of 16S rDNA, and thirty-one sequences were compared against the EzTaxon database for taxonomic classification. Twenty-nine of these isolates showed greater than 99% similarity to previously cultured Streptomyces species. Notably, two isolates derived from house garden soil were identified as potential novel species, exhibiting antibacterial activity against Escherichia coli (ATCC 25218) and Staphylococcus aureus (ATCC 25923) by inhibiting growth on Mueller-Hinton agar plates using the cross-streak method.