Uji aktivitas antagonistik Lactobacillus sp. yang diisolasi dari usus ikan betutu, Oxyeleotris marmorata

Abstract

This study was conducted to examine the antagonistic activity of probiotic bacteria isolated from the digestive tract of fish (Oxyeleotris marmorata). Fish having an average weight of 500 grams were obtained from fish ponds in Tetey Village, North Minahasa Regency. Fish were dissected, the intestine was separated from the other internal organs. The intestine was then weighed as much as 1 gram, cut into small pieces and then crushed using a mortar until smooth. The results of the scour were transferred to a test tube and 9 mL of NaCl solution was added, then centrifuged at 1000 RPM for 10 minutes for 2 times. The supernatant was diluted to obtain a concentration of 10^-2 to 10^-3. The dilution was spread onto MRS media and incubated for 24-48 hours at 28^oC. Growing colonies were cultured on MRS agar, purified and propagated. The pure isolate obtained were then subjected to Gram Stain, biochemical tests and antagonistic tests. The results of the study found that the characteristics of the bacteria were round shape, milky white in color, rod-shaped and Gram positive, and biochemically identified as Lactobacillus sp. These bacteria had strong antagonistic activity against A. hydrophila which was indicated by the presence of a clear zone with a diameter of 26.88 mm around the probiotic disc.