Ecological, Molecular, and Antimicrobial Characterization of Cyanobacteria Isolated from different Springs in Khurmal-Halabja, Kurdistan Region, Iraq

Cyanobacteria are known to produce biologically active compounds with potential antimicrobial properties. This study aimed to perform molecular identification and evaluate the antimicrobial activity of cyanobacteria from four springs in Khurmal-Halabja, in the Kurdistan Region of Iraq between September 2024 and February 2025. During this study period, physicochemical parameters such as temperature, pH, and nutrient levels were determined and monitored. Isolates of cyanobacteria were cultured on BG-11 medium, and through morphological studies combined with 16S rRNA gene sequencing, nine species were identified, including Nostoc commune, Phormidium autumnale (Microcoleus autumnais), Aphanothece caldariorum, Microcoleus vaginatus, Microcoleus pseudoautumnalis, Gloeocapsa rupicola, Limnothrix planktonica, Thermocoleostomius sinensis, and Pseudanabaena yagii. Ethanol extracts from four selected species were tested against Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli by the agar well diffusion method. Microcoleus pseudoautumnalis exhibited the strongest activity, showing a 16-mm inhibition zone against Staphylococcus aureus while Microcoleus vaginatus had a broader spectrum of activity. There was greater susceptibility demonstrated by Gram-positive strains compared to Gram-negative strains. The research illustrates that cyst-forming cyanobacteria from Khurmal may be relevant for biotechnological and ecological applications.