Bioremediation of Pharmaceutical Wastewater using Oscillatoria subsalsa and Oscillatoria flos-aquae: Efficiency in Contaminant Removal, Phytochemical Analysis and Antibacterial Activity against Biofilm-Forming Bacteria

This study investigates the potential of cyanobacteria, specifically Oscillatoria subsalsa and Oscillatoria flos-aquae, for the bioremediation of pharmaceutical wastewater and their effectiveness in eliminating biofilm forming, multidrug-resistant bacteria. Cyanobacteria species were collected from the Mandapam coast in India and analyzed for their ability to treat pharmaceutical effluents. Phytochemical compounds in solvent extracts were assessed prior to remediation. The cyanobacteria were evaluated for their effectiveness in reducing pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia, nitrite, nitrate and phosphate levels in wastewater. Antibacterial activity was analyzed against biofilm-forming bacterial isolates from pharmaceutical effluents. Both O. subsalsa and O. flos-aquae demonstrated significant reductions in environmental contaminants. O. subsalsa was more effective in reducing COD, while O. flos-aquae excelled in reducing nitrate and nitrite levels. Phytochemical analysis revealed the presence of alkaloids, carbohydrates, flavonoids, phenols, saponins, tannins, terpenoids, sterols and quinones, indicating a rich profile of bioactive compounds. The antibacterial tests showed that both cyanobacterial species had significant antibacterial properties, with O. flos-aquae displaying stronger and more consistent activity, particularly against Gram-negative bacteria. The study highlights the potential of O. subsalsa and O. flos-aquae in wastewater treatment and their capability to combat multidrug-resistant pathogens. These findings suggest that cyanobacteria offer a promising, sustainable approach for effective bioremediation and management of pharmaceutical wastewater.