Potential of Secondary Metabolite from Marine Heterotrophic Bacteria against Pathogenic Bacteria in Aquaculture

Abstract

Marine bacteria including heterotrophic bacteria are the most numerous organisms in nature and are capable of producing secondary metabolites. The secondary metabolite produced is a molecular compound produced from the secondary metabolic process, generally can be in the form of antibiotics, enzyme inhibitors, toxins, growth regulators, hormones, and insecticides. This study aims to examine the inhibitory ability of secondary metabolites of heterotrophic bacteria to the activity of pathogenic bacteria Aeromonas hydrophilla, Pseudomonas aeruginosa, and Vibrio alginolyticus. Around 10 heterotrophic bacterial isolates from the Marine Microbiology Laboratory collection, Fisheries and Marine Sciences Faculty, University of Riau was tested on pathogenic bacteria based on the Kirby-Bauer disk diffusion method. The results showed that all heterotrophic bacterial isolates were capable of inhibiting the growth of pathogenic bacteria such as A. hydrophilla (P), P. aeruginosa (Q), and V. alginolyticus (R). Vagococus fluvialis isolates are the best heterotrophic bacterial isolates in producing secondary metabolites compared to 9 other isolates. Where the clear zone formed is wider, that is 12.35 mm with the results of the activity test of 1877.78 mm2/ml. Based on the results, the heterotrophic bacteria are capable of producing secondary metabolites that inhibit the growth of pathogenic bacteria.