ANTIMICROBIAL ACTIVITY OF SOME MARINE MICROALGAE AGAINST COMMON BACTERIAL DISEASES IN AQUACULTURE IN CHATTOGRAM, BANGLADESH

Abstract

The present investigation aimed to study antimicrobial activity of indigenous marine microalgae Tetraselmis, Chlorella and Nannochloropsis against Gram-negative Aeromonas hydrophilla and Gram-positive Staphylococcus and Lysinibacillus sphaericus isolated from diseased fish in Chattogram, Bangladesh. The highest antimicrobial activity was found in the extract of Tetraselmis which exhibited an inhibitory effect against Aeromonas hydrophilia (1.99mm). Moreover, Chlorella showed the highest inhibitory activity against Staphylococcus (1.262mm). However, Nannochloropsis showed no sensitivity against any of these three bacteria. Chlorella showed the MIC value of 20mg/ml against Staphylococcus and Tetraselmis at 10mg/ml against Aeromonus hydrophila. The observed antimicrobial activities might be linked to the contents of the algal extracts containing valuable fatty acids, carotenoids, chlorophylls, hycocyanin, phycoerythrin, phycobiliprotein and phenolic compounds that need to be determined. The studied microalgae could be considered as a potential natural source of bioactive compounds with antimicrobial activities.