Cyanobacteria are natural enormous sources of various biologically active compounds with great contributions
in different industries. This study aimed to explore and characterize novel cyanobacterial isolates with antioxidant activity and potent phycoremediation ability from Egyptian wastewater canals. The in vitro biological
activity of these isolates and their potential ability to take up nutrients and heavy metals from wastewater were
examined. The obtained isolates were sequenced and deposited in database under accession numbers,
KY250420.1, KY321359.1, KY296359.1 and KU373076.1 for Nostoc calcicola, Leptolyngbya sp., Nostoc sp., and
Nostoc sp., respectively. Leptolyngbya sp. (KY321359.1) showed the lowest identity (90%) with the nearest deposited sequence in database. While the isolate Nostoc sp. (KU373076.1) showed the highest total phenolic
content as well as the highest levels of caffeic, ferulic and gallic acids. Consequently, it presented the highest
antioxidant scavenging activity. All studied isolates revealed potent ability in chelating nutrients and removing
heavy metals from wastewater. In conclusion, this study provides a taxonomic, biochemical and molecular
evidence of four novel cyanobacterial isolates with antioxidant activity and potential phycoremediation ability.