Abstract

Micro algae Spirulina platensis, Haematococcus pluvialis and Botryococcus braunii are cultured commercially and their productions are established in different parts of the world. In the present investigation the antibacterial properties of different solvent extracts of these three micro algae were evaluated. The maximum phenolic contents (128, 131, 110 ?g/mg) was recorded in chloroform extracts of S. platensis, H. pluvialis and ethyl acetate extract of B. braunii. Hexane, chloroform, ethylacetate, acetone and methanol extracts of S. platensis, B. braunii and H.pluvialis were tested against important clinical bacterial isolates such as Bacillus subtilus, Bacillus cereus, Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Listeria monocytogenes, Micrococcus luteus, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus,Streptococcus fecalis and Yersinia enterocolitica. The antibacterial activity was determined by agar-well diffusion assay and minimum inhibitory concentration (MIC). Chloroform and ethlyacetate extracts of S.platensis showed highest inhibition against B.subtilus (18.12 mm and MIC at 200 ppm), while chloroform extract of H. pluvialis recorded highest inhibition against B. subtilus (17.32 mm and MIC at 150 ppm). In B. braunii, ethlyacetate extract exhibited maximum inhibition against E. aerogenes (15.11 mm and MIC at 300 ppm). We conclude that, S. platensis, H. pluvialis and B.braunii extracts can be used as bacteriostatic agents for suitable applications.