Phytochemical and antimicrobial activity of green microalgae from Vellar Estuary,southeast coast of India

Objective:To determine the phytochemicals and screen the antimicrobial potential of Desmococcus olivaceus(D.olivaceus)and Chlorella vulgaris(C.vulgaris)against human bacterial pathogens.Methods:D.olivaceus and C.vulgaris were collected and confirmed through morphological structures.Phytochemicals were analyzed and confirmed by chemical methods.Thin layer chromatography was performed to evaluate the bioactive compounds present in the solvent extracts.Antimicrobial activity of the extract obtained from dried green microalgae was tested against Gram negative and Gram positive bacteria using agar disc diffusion method.The Gram negative bacteria like Klebsiella pneumonia,Proteus mirabilis,Vibrio cholerae,Salmonella typhi,Escherichia coli and Gram positive bacteria including Staphylococcus aureus,Bacillus subtilis,Enterococcus sp.,Clostridium botulinum(C.botulinum)and Nocardia sp.were selected for analysis.The cultures were obtained from Microbial Culture Maintenances Laboratory,Department of Medical Microbiology,Rajah Muthaiah Medical College,Annamalai University,Tamil Nadu,India.Results:Seven bioactive compounds were detected viz.,phenols,tannin,flavanoids,saponins,terpenes,carbohydrates,alkaloids and steroids.In Gram negative bacteria,Proteus mirabilis treated with ethanol extract of D.olivaceus showed the maximum inhibition zone(17.2 mm),whereas in Gram positive bacteria,C.botulinum treated with diethyl ether extract showed inhibition zone of 19.0 mm.In test for C.vulgaris,Gram negative bacteria Salmonella typhi treated with ethanol extract showed the maximum inhibition zone(13.0 mm),whereas in Gram positive bacteria,C.botulinum treated with chloroform extract of C.vulgaris showed the maximum inhibition zone of 15 mm.Conclusions:The results clearly indicated that D.olivaceus and C.vulgaris contain promising antibacterial compounds.