Author(s): MALA R, SAROJINI M, SARAVANABABU S, UMADEVI G
Various organic and aqueous extracts of Spirulina platensis were screened for their antibacterial activities. The extracts were tested against different species of human pathogenic bacteria by the agar-solid diffusion method. Water extract of Spirulina platensis showed maximum antimicrobial activity of 18.0mm against Klebsiella pneumoniae (NCIM2063) and a minimum activity of 10.0mm against Proteus vulgaris (NCIM2027). All the tested microorganisms were resistant to methanol, ethanol and propanol extracts except Pseudomonas aeruginosa (NCIM2076) and Escherichia coli (NCIM2065) which exhibited a least inhibition zone of 7.0 and 8.0 mm respectively in propanol. Acetone extract of Spirulina platensis also showed the highest biological activity of 17.0 mm against Klebsiella pneumoniae (NCIM2063) , moderate activity of 11.0 mm against Salmonella typhi (NCIM2080), and 10.0 mm against Pseudomonas aeruginosa (NCIM2076), Escherichia coli (NCIM2065) and Staphylococcus aureus (NCIM2079). Sequential extract of Spirulina exhibited maximum antimicrobial activity. Inhibition zone of 25.3 mm was observed for Klebsiella pneumoniae and 16.0 mm for Proteus vulgaris. FTIR Spectrum of sequential extract showed strong bands at 1047,1383,1640,2361, and 3450 cm -1 .