Antimicrobial agents derived from heterotrophic bacteria againts pathogenic bacteria

Abstract Pathogenic bacteria often cause problems in fish farming. Prevention efforts using synthetic antibiotics may engender negative impacts on the environment. Accordingly, the use of natural antimicrobial compounds is required to minimize the risk. There are several types of heterotrophic bacterias which can produce antimicrobial agents. This study aims to determine the ability of the secondary metabolites extract isolated from heterotrophic bacteria in inhibiting the growth of pathogenic bacteria. The method used in this study was an experimental method. Four isolates of bacterial heterotrophic originating from waters of Sungai Pakning were cultured on nutrient broth for 10 days which would later be extracted by using ethyl acetate. The secondary metabolites extract of the heterotrophic bacteria was tested on 3 pathogenic bacteria that usually attack fish. The antimicrobial test results indicated that the secondary metabolites extract of the heterotrophic bacteria was able to inhibit the growth of Aeromonas salmonicida bacteria from 11.77 to 12.53 mm, Edwarsiella tarda bacteria from 10.70 to 12.40 mm and Edwarsiella ictaluri bacteria from 10.97 to 12.38 mm. Overall, the inhibition of the strongest pathogenic bacteria was JS11 isolates (Bacillus sp. strain SMMA8 code access LN869534.1). Heterotrophic bacteria produced secondary metabolites which can inhibit the growth of pathogenic bacteria in fish. Antimicrobial agents of heterotrophic bacteria are potentially to be developed.