PJB-2024-152
MARINE CYANOBACTERIA: ASSESSMENT OF TOXICITY AND ANTIMICROBIAL POTENTIAL OF CRUDE SAMPLES AND ISOLATED STRAINS FROM COASTAL WATERS OF KARACHI, PAKISTAN
SAMINA DAWOOD
Abstract
Microalgal communities, such as, cyanobacteria, diatoms and dianoflagellates, etc., generally bloom under eutrophic conditions in both fresh and marine water bodies. Blooms of harmful algae have been reported from various parts of the world that inflicts losses to the economy and environmental/human health. Here we present on antimicrobial activity and lethal/toxic effects in a rat model of some cyanobacteria collected from the coastal waters (Manoraora Channel, Karachi, Pakistan). Antibacterial activity was targeted against nine species of gram +ve and gram -ve bacteria, namely, Bacillus subtilus , Staphlococcus aureus, Staphlococcus albus, Streptococcus pyogens and Streptococcus fecalis, Pseudomonas aeruginosa, Klebsiella sp., Eschierichia coli, Salmonala typhi. The cyanobacterial extracts showed promising antibacterial activity against Gram +ve bacteria. The ethanol and chloroform extracts showed high antibacterial activity compared to water extracts. Bacillus subtilus was the most susceptible to cyanobacterial extract. Acute lethal toxicity was caused by one marine cyanobacterial species, Leptolyngbya angustissima and a mixed crude sample for which LD50 values were recorded. All extracts generally showed typical signs of hepatotoxicity, though some of the symptoms resembled neurotoxicity. The data is indicative of the presence of toxic microalgae for which regular monitoring is inevitable.
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