10.22376/ijpbs.2019.10.1.p1-12 Volume 3 Issue 3 2012 (July - September) The phytochemical screening of the various extracts of lessThan i greaterThan Spirodela polyrrhiza lessThan /i greaterThan revealed the presence of alkaloids, steroids, flavonoids and saponins. Fourteen fractions were elucidated from the ethanolic extract using the silica gel column chromatography. Antimicrobial activities of the ethanol and fractions of ethanolic extract of lessThan i greaterThan S. polyrrhiza lessThan /i greaterThan against Gram-negative strains of lessThan i greaterThan Aeromonas hydrophila lessThan /i greaterThan (AH1), lessThan i greaterThan Psedomonas putida lessThan /i greaterThan (ATCC 49128), lessThan i greaterThan P. aeruginosa lessThan /i greaterThan (ATCC 35072), lessThan i greaterThan P. fluorescens lessThan /i greaterThan (PF1), lessThan i greaterThan Vibrio parahaemolyticus lessThan /i greaterThan (ATCC 17802), lessThan i greaterThan V. Alginolyticus lessThan /i greaterThan (ATCC 17749), lessThan i greaterThan E. coli lessThan /i greaterThan (EC1) and Gram-positive strain of lessThan i greaterThan Staphylococcus aureus lessThan /i greaterThan (ATCC 6538) and fungal pathogens, lessThan i greaterThan Candida albicans lessThan /i greaterThan and lessThan i greaterThan Saprolegnia parasitica lessThan /i greaterThan were done by disc diffusion methods showed that the extract possess broad spectrum of activity against the test organisms with diameter of zones of inhibition ranging from 9.0 - 16.0 mm. The minimum inhibitory concentration (MIC) of the extract against the test organisms were found to fall between 30 - 200 µg/ml. Basanta Kumar Das, Durga Prasad Das, Jyotirmayee Pradhan, Barsha Priyadarshinee, Ipsita Sahu, Pragyan Roy And Bibudhendra Kumar Mishra Antimicrobial activity, alkaloid, Candida albicans, Minimum Inhibitory Concentration (MIC), phytochemical, Staphylococcus aureus 822-833