Ph. D thesis at the faculty of Science, University of Basra, discussed "Biological Applications of Zinc Oxide Nanoparticles Synthesized Using the Green Method with Aeromonas caviae Bacteria." The thesis, by researcher Shaimaa Awad Bachii, aimed to identify the potential impact of the physical and chemical properties of the Shatt al-Arab River on the diversity of microbial communities. Water samples were collected from seven locations along the river, specifically from Maqal Port, Umm Qasr Port, the Al-Sadr Hospital outlet on Shatt al-Arab, Abu Al-Fulus, Al-Faw - Ras Al-Bisha, Ibn Khaldoun Ship, and Khalid Bridge. Water culture was performed, and 33 bacterial samples were recovered using 16S rDNA sequencing. The most frequently occurring bacterium, Aeromonas cavia, was selected for the synthesis of zinc nanoparticles. The success of the synthesis process was determined through morphological characterization, particle purity, size, and charge. The resulting nanoparticles were applied in biomedical applications as an antibacterial agent against pathogenic isolates, an anti-biofilm agent, and an antioxidant in RO drinking water disinfection, as well as in the breakdown of dyes such as malachite green and hemolysis.