Seleksi bakteri probiotik untuk pengendalian penyakit vibriosis pada ikan kerapu macan (Epinephelus fuscoguttatus)

Abstract

Vibriosis is a bacterial disease affecting farmed fish including grouper. Disease control usually uses antibiotic but can lead to ecological inbalance and antibioticresistant pathogens. The use of probiotic bacteria is one of the methods in aquaculture that is used to control infectious diseases. The aims of this study were to obtain and isolate pathogenic Vibrio in the tiger grouper, to select bacterial probiotic candidates in controlling vibriosis, to evaluate efficacy of probiotic bacterial administration in controlling vibriosis in tiger grouper fry, and to evaluate probiotic bacterial candidates in enhancing immune responses. The first step was isolation and characterization of pathogenic bacteria as causative agent of vibriosis on grouper. Secondly, selection of probiotic candidate bacteria was conducted from the coral reef and tiger grouper fish farming environment including isolation of probiotic candidates, selection of probiotic candidates using inhibition test, co-culture method, and pathogenicity test of selected probiotic candidates. The third and fourth steps were administration of probiotic candidate bacteria on tiger grouper fry and juvenile, respectively, on feed for 28 days, and challenge test was performed at day-29. The result indicated that V6 isolate was the most pathogenic among isolates. Moreover, from 124 isolates, based on selection of probiotic candidates bacteria using inhibition zone and co-culture methods, there were found four potential isolates namely K7, K8, K21, T41, and K15, K55, K68, T36, respectively. Four isolates, namely K7, K8, T36 and T41, had high survival rate of fish in pathogenicity test. Furthermore, T36 isolate may decrease pathogenic Vibrio population, increase immune response, survival rate and growth rate of tiger grouper. According to gene sequencing analysis using 16S-rRNA, V6 dan T36 were Vibrio parahaemolyticus and Bacillus cereus, respectively.