Antimicrobial Activity of Sea lettuce (Ulva reticulata) on Selected Microorganisms

This is an experimental research that tested 95% ethanolic extract of Ulva reticulata for the determination of Minimum Inhibitory Concentration (MIC) on the test bacteria (E. coli and S. aureus) and the test fungi (A. niger and C. albicans). Ulva reticulata samples were collected from Bayabas and Gusa, Cagayan de Oro City, where this algae is abundant. The samples were washed with tap water and rinsed to remove dirt, dust and pebbles. They were air-dried, chopped into small pieces, soaked with 95% ethyl alcohol for 24 hours, and then wrung with cheesecloth. The extract obtained was concentrated in a vacuo for 11 hours at 75 0C. Minimum Inhibitory Concentration (MIC) of the extract against selected microorganisms were determined, and was streaked on Trypticasein Soy Agar (TSA) for the determination of bactericidal concentration, which provide information whether the substance is  bacteriostatic or bactericidal. The study revealed that the minimum inhibitory concentration on E. coli was 31.25 g/L while for S. aureus was 15.63 g/L. However, the results of plating in TSA for Minimal Bactericidal Concentration (MBC) showed that the substance was bacteriostatic. Further, the MIC on test fungi showed no inhibition on the two test organisms. Hence, determination of MFC was not performed.

 

Keywords: Ethanolic extract, Ulva reticulate, Minimum Inhibitory Concentration