Antimicrobial activity of certain fresh water microalgae from Thamirabarani River, Tamil Nadu, South India

Abstract

To evaluate the antimicrobial potential of fresh water microalgaeviz., 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. andSpirogyra condensata (Vaucher) Kuetz against human bacterial pathogens. Antimicrobial study was carried out by disc diffusion method against the pathogensviz., 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) andStreptococcus pyogenes. The methanolic extract ofO. sancta showed the antibacterial activity against three pathogensviz., P. mirabilis, P. vulgaris andS. aureus with the inhibition zones of 10, 8 and 8 mm, respectively. The methanolic and ethanolic extracts ofL. birgei exhibited the antibacterial activity against two pathogensi.e. P. mirabilis andP. vulgaris with the maximum zone of inhibition of 8 and 8 mm, respectively. The ethanolic extracts ofO. echinospermum displayed the antibacterial activity againstS. typhi andP. mirabilis with the maximum of zone of inhibition (7 mm). The methanolic extracts ofS. decimina exhibited the antibacterial activity againstS. aureus andP. mirabilis with the maximum zone of inhibition of 12 and 9 mm, respectively. The ethanolic extracts ofS. grantiana showed the anti-bacterial activity against three organismsi.e. E. coli, P. vulgaris andP. mirabilis with the zone of inhibition of 9, 10 and 9 mm, respectively. The methanolic extracts ofS. crassa exhibited the antibacterial activity againstP. mirabilis with the maximum zone of inhibition (9 mm). The methanolic extracts ofS. biformis exhibited the antibacterial activity againstP. vulgaris with the maximum zone of inhibition (8 mm). 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.