ABSTRACT
Objective:To evaluate the antimicrobial potential of fresh water microalgae viz., Oscillatoria sancta (O. sancta) (Kuetz) Gomont., Lyngbya birgei (L. birgei) Smith G.M., Oedogonium echinospermum (O. echinospermum), Spirogyra decimina (S. decimina) (Muller) Kuetz., Spirogyra grantiana (S. grantiana) Transeau., Spirogyra crassa (S. crassa), Spirogyra biformis (S. biformis) Jao. and Spirogyra condensata (Vaucher) Kuetz against human bacterial pathogens. Methods:Antimicrobial study was carried out by disc diffusion method against the pathogens viz., Escherichia coli (E. coli) (ATCC 35218), Staphylococcus aureus (S. aureus) (ATCC 6538), Salmonella typhi (S. typhi) (MTCC 733), Proteus vulgaris (P. vulgaris), Proteus mirabilis (P. mirabilis) and Streptococcus pyogenes. Results: The methanolic extract of O. sancta showed the antibacterial activity against three pathogens viz., P. mirabilis, P. vulgaris and S. aureus with the inhibition zones of 10, 8 and 8 mm, respectively. The methanolic and ethanolic extracts of L. birgei exhibited the antibacterial activity against two pathogens i.e. P. mirabilis and P. vulgaris with the maximum zone of inhibition of 8 and 8 mm, respectively. The ethanolic extracts of O. echinospermum displayed the antibacterial activity against S. typhi and P. mirabilis with the maximum of zone of inhibition (7 mm). The methanolic extracts of S. decimina exhibited the antibacterial activity against S. aureus and P. mirabilis with the maximum zone of inhibition of 12 and 9 mm, respectively. The ethanolic extracts of S. grantiana showed the anti-bacterial activity against three organisms i.e. E. coli, P. vulgaris and P. mirabilis with the zone of inhibition of 9, 10 and 9 mm, respectively. The methanolic extracts of S. crassa exhibited the antibacterial activity against P. mirabilis with the maximum zone of inhibition (9 mm). The methanolic extracts of S. biformis exhibited the antibacterial activity against P. vulgaris with the maximum zone of inhibition (8 mm). Conclusions: These results give an indication of the presence of promising antibacterial compounds in the plants under studied. Further phytochemical studies are needed to elucidate the components responsible for antibacterial activity of these extracts against bacteria.