Antioxidant activity and phycoremediation ability of four cyanobacterial isolates obtained from a stressed aquatic system

[Display omitted] •Stressed aquatic system stimulate cyanobacteria for important secondary metabolites induction.•Explore eco-friendly cyanobacterial isolates a sustainable choice for wastewater treatment.•Nostoc sp. (KU373076.1) showed the highest total phenolic content and phycoremediation ability.•All Cyanobacterial isolates displayed high DPPH scavenging ability.•All studied isolates decreased lead, cadmium, Zinc and cobalt by 100%. 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.